Cover page
Image Name: Tiny Galaxies - stellar clusters.
Open Cluster NGC 376,This image from the NASA/ESA Hubble Space Telescope captures a small portion of
the Small Magellanic Cloud (SMC). The SMC is a dwarf galaxy and one of the Milky Way’s nearest neighbors,
lying only about 200,000 light-years from Earth. It makes a pair with the Large Magellanic Cloud, and both
objects are best seen from the Southern Hemisphere, but are visible from some northern latitudes as well. Read
more here: https://science.nasa.gov/missions/hubble/hubble-captures-a-glittering-neighbor/
Managing Editor Chief Editor Editorial Board Correspondence
Ninan Sajeeth Philip Abraham Mulamootil K Babu Joseph The Chief Editor
Ajit K Kembhavi airis4D
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Jorunal Publisher Details
Publisher : airis4D, Thelliyoor 689544, India
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i
Editorial
by Fr Dr Abraham Mulamoottil
airis4D, Vol.1, No.12, 2023
www.airis4d.com
Welcome to the 12th edition of airis4D, Vol.1, 2023! We have completed the first volume of airis4D.
This edition delves into diverse topics like astronomical phenomena, biological age, vascular aging, and the
intricacies of workaholism and depression. Each article offers insightful perspectives and knowledge on these
intriguing subjects, enriching our understanding of complex aspects of science, health, and human behavior.
”Introduction to Quantum Machine Learning - Part 3” by Blesson George presents a comprehensive dive
into quantum computing concepts, focusing on qubits, quantum circuits, and the intriguing model of adiabatic
quantum computing. The article delves into the adiabatic theorem’s role in time-dependent Hamiltonians, offer-
ing an alternative quantum computation approach. It explores the meticulous process of encoding, preparing,
annealing, and measuring within the adiabatic model, showcasing its potential for efficient problem-solving.
Furthermore, the article introduces quantum annealing as an optimization technique leveraging qubits unique
traits for complex problem landscapes. Both adiabatic quantum computing and quantum annealing emerge as
promising frontiers in the quantum computing realm, presenting innovative solutions across diverse domains as
quantum technologies advance.
”Multimodal NLP: Understanding the World Like Us” by Jinsu Ann Mathew introduces the concept of
Multimodal Natural Language Processing (NLP) in Artificial Intelligence (AI), aiming to mimic human senses
for a comprehensive understanding of information. The article explores how traditional AI focuses on single
modalities like pictures or text, whereas multimodal AI combines information from different sources such as
images, text, sound, and smell to grasp a richer context. It elucidates the working of multimodal AI through
its Input, Fusion, and Output modules, drawing parallels to human sensory perceptions. The Fusion Module,
likened to the brain, integrates data from various modalities through techniques like early fusion, alignment-
based fusion, and late fusion. The Output Module translates this fused information into understandable or
actionable outcomes, mirroring human interaction. Multimodal NLP represents a significant leap in creating
AI systems that engage with humans in a manner akin to our complex communication, signaling a promising
stride toward more intelligent and versatile machines.
”Integrated Gradients: A Model Interpretability Technique for Machine Learning” by Linn Abraham
introduces a method for developing Interpretable Machine Learning models. Usually, machine learning models
are considered black boxes. He discusses ways in which this limitation may be overcome.
In his fifth article in the series, ”Black Hole Stories 5, Some Concepts in Einsteins General Theory of
Relativity”, Professor Ajit Kembhavi narrates the fundamentals for understanding General Relativity through
simple illustrations. The introduction of Special Relativity brought many changes in our understanding that
need to be clear when we study General Relativity. This article provides those details.
”Exploring the Enigmatic World of Be/X-ray Binaries” dives into high-mass X-ray binaries, focusing
on Be/X-ray binaries, where a massive Be star interacts with a neutron star or black hole. These binaries,
characterized by their intense X-ray emissions, exhibit intriguing dynamics between the Be star’s circumstellar
disk and the compact object. The article details the unique traits of Be stars, their circumstellar disks, and the
neutron stars dense nature, explaining the X-ray emission bursts resulting from the interaction between the
neutron star and the disk. It highlights the transient behavior of these binaries, providing valuable insights into
accretion physics, mass transfer dynamics, and neutron star properties. Additionally, it outlines observational
techniques—X-ray, optical, infrared, and radio astronomy—used to study these systems, emphasizing the
significance of Be/X-ray binaries as cosmic laboratories for understanding extreme astrophysical conditions and
fundamental processes in the cosmos. The article serves as an introduction to forthcoming explorations into
various categories of Be/X-ray binaries, promising deeper insights into these intriguing astrophysical systems.
The article ”Exploring the Complexities of Ageing Process with respect to Biological age and Chronological
age” investigates ageing through the lenses of biological and chronological age. It emphasizes that while
chronological age measures time since birth, biological age considers genetic, lifestyle, and physiological factors,
providing a more accurate gauge of ageing. The exploration of ageing biomarkers like telomere shortening,
DNA methylation, and vascular ageing contributes to understanding the ageing process. The distinction between
biological and chronological age has implications for health outcomes, interventions, and legal considerations.
Epigenetic studies offer promising avenues for accurately calculating biological age, impacting discussions about
legal age changes and aligning them with biological age. Biomarkers associated with vascular ageing, such
as arterial stiffness, endothelial function, and inflammatory factors, offer insights into cardiovascular disease
risks in ageing individuals. Further research on these biomarkers is essential to improve clinical relevance and
enhance predictions related to vascular ageing-related conditions. Understanding these complexities provides
opportunities for interventions, longevity, and healthy ageing.
The article ”Workaholism and Depression” explores the difference between healthy hard work and detri-
mental workaholism, focusing on their impact on mental health and personal well-being. It distinguishes
between self-motivation that fosters healthy hard work and excessive workaholism that leads to stress, low self-
esteem, and depression. It highlights societal pressures that can push individuals into unsuitable professions,
resulting in stress and obsession, leading to depression. The piece emphasizes the withdrawal from social life
by workaholics and the adaptability of hard workers in various aspects of life. Additionally, it discusses the
genetic links between mood disorders and clinical depression and emphasizes the health impacts of workaholism
compared to the balanced approach of hard workers. The article encourages introspection to discern between
stressful work and healthy hard work, emphasizing passion and internal drive as crucial factors. In conclusion,
it cites Thomas Edisons approach as an example, showcasing his willingness to learn from failures—a trait of
hard workers who view failures as opportunities for growth.
As we conclude the inaugural year of airis4D Journal, we extend our heartfelt gratitude to our readers,
contributors, and supporters. This year has been a journey of exploration, discovery, and learning. Were
committed to continuing our pursuit of knowledge and sharing insightful content across diverse domains in the
years ahead. Thank you for being part of our successful journey, and heres to many more years of insightful
discoveries and enlightening discussions with airis4D.
iii
Contents
Editorial ii
I Artificial Intelligence and Machine Learning 1
1 Introduction to Quantum Machine Learning - Part 3 2
1.1 Adiabatic Quantum Computing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2 Quantum Annealing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 Multimodal NLP : Understanding the World Like Us 5
2.1 What is Multimodal NLP? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 Working of Multimodal AI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3 Input Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.4 Fusion Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.5 Output Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3 Integrated Gradients: A Model Interpretability Technique for Machine Learning 10
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.2 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.3 Need for a Baseline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.4 Why not just use Gradients? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.5 Inspiration from Game Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.6 Evaluation of Attribution Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.7 Integrated Gradients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
II Astronomy and Astrophysics 15
1 Black Hole Stories 5
Some Concepts in Einstein’s General Theory of Relativity 16
1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
1.2 The Schwarzschild Metric . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
1.3 Geodesics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
1.4 Types of Geodesics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
1.5 Conserved Quantities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2 Exploring the Enigmatic World of Be/X-ray Binaries 21
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.2 Understanding Be/X-ray Binaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.3 Observational Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.4 Importance of the Study of Be High-Mass X-ray Binaries . . . . . . . . . . . . . . . . . . . . 24
CONTENTS
III Biosciences 26
1 Exploring the Complexities of Ageing Process with respect to Biological Age and
Chronological Age 27
1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
1.2 Telomere Shortening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
1.3 Epigenetic Regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
1.4 DNA Methylation and Histone Modifications . . . . . . . . . . . . . . . . . . . . . . . . . . 29
1.5 CpG Islands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
1.6 Biomarkers of Biological Vascular Aging . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
1.7 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
IV General 34
1 Workaholism and Depression 35
1.1 The Myths about Workaholism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
1.2 Fundamental Differences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
1.3 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
v
Part I
Artificial Intelligence and Machine Learning
Introduction to Quantum Machine Learning
- Part 3
by Blesson George
airis4D, Vol.1, No.12, 2023
www.airis4d.com
In our previous article, we embarked on a detailed exploration of the fundamental concepts of quantum
computing surrounding qubits and quantum circuits. Delving deeper into the realm of quantum computing, lets
augment our understanding of these intriguing subjects with a more nuanced discussion. Qubits, the quantum
counterparts to classical bits, exhibit a remarkable property known as quantum superposition, allowing them to
exist in multiple states simultaneously. This unique characteristic forms the bedrock of quantum information
processing, extending the possibilities of computation beyond the confines of classical binary systems. Moreover,
our examination of quantum circuits revealed them as the building blocks of quantum computation, where gates
such as the NOT gate and Hadamard gate play pivotal roles in manipulating and entangling qubits. In this
article, we discuss about an alternative model called adiabatic quantum computing, which manipulates states
using Hamiltonian operator.
1.1 Adiabatic Quantum Computing
1.1.1 Adiabatic Theorem
According to the quantum adiabatic theorem, a quantum system that begins in the non-degenerate ground
state of a time-dependent Hamiltonian will remain in the instantaneous ground state provided the Hamiltonian
changes sufficiently slowly.
The solution to the time-independent Schr
¨
odinger equation provides a straightforward solution when
dealing with a time-independent Hamiltonian.
i
d
dt
|ψ(t) = H|ψ(t)
with the initial quantum state given by
|ψ(t) = exp(iHt)|ψ(0)
However, the complexity of the problem increases significantly when the Hamiltonian is time-dependent. In
such cases, the evolution of the system becomes more intricate.
In adiabatic quantum computing model, a computation is defined by two Hamiltonians, namely H
initial
and H
final
, where a Hamiltonian is essentially a Hermitian matrix. The ground state of H
initial
, characterized
by the eigenvector with the smallest eigenvalue (also referred to as the ground state), must be a readily preparable
1.2 Quantum Annealing
state, such as a tensor product state.
The result of the adiabatic computation is the ground state of the final Hamiltonian, H
final
. Consequently,
we select an H
final
whose ground state represents the solution to the given problem. An essential requirement
is that the Hamiltonians are local, meaning they involve interactions only among a constant number of particles.
This constraint can be likened to allowing gates that operate on a constant number of qubits in the standard
model. This condition ensures a concise classical description of the Hamiltonians by listing the matrix entries
of each local term.
The runtime of the adiabatic computation is dictated by the minimal spectral gap of all the Hamiltonians
along the straight line connecting H
initial
and H
final
, denoted as H(s) = (1 s)H
initial
+ sH
final
.
Within the adiabatic model, several key steps unfold, each playing a crucial role in the computational
process:
1. Encode Your Problem (Boolean SAT Problem): In the initial phase, the problem at hand is encoded,
specifically in terms of a Boolean satisfiability (SAT) problem. This step involves formulating the logical
conditions of the problem in a way that aligns with the Boolean framework.
2. Prepare Initial State of Qubits (Program Your Problem): Following the encoding, the next step involves
the preparation of the initial state of qubits. This is akin to programming the quantum system with the
information encapsulated in the Boolean SAT representation, setting the stage for subsequent quantum
operations.
3. Annealing Process (Slowly Change from Initial to Final State): The heart of the adiabatic computation
lies in the annealing process. Here, a gradual transformation occurs, moving the quantum system from
its initial state to the final state. This gradual evolution is essential for maintaining adiabaticity, ensuring
that the system remains in its ground state throughout the process.
4. Measure Your Answer: Finally, the computational outcome is determined through the measurement of
the quantum system. The measured result provides the solution to the encoded problem, and the quantum
nature of the system allows for the exploration of multiple possibilities simultaneously, enhancing the
efficiency of certain computations.
1.2 Quantum Annealing
Quantum annealing is a computational paradigm that leverages principles from quantum mechanics to
tackle complex problem-solving tasks. At its core, it is an optimization technique designed to find the most
efficient solution to a given problem. Unlike classical computing, which relies on bits, quantum annealing
employs qubits—quantum bits—that can exist in multiple states simultaneously through superposition.
The process begins by encoding the problem into a set of parameters that can be represented in the language
of quantum mechanics. These parameters are then mapped onto qubits, configuring the quantum system to
embody the problem space. Quantum annealing distinguishes itself through its unique annealing process, a
gradual transformation from an easily preparable initial state to a final state that encodes the solution sought.
During annealing, the quantum system explores various configurations, adapting to the problem’s land-
scape. This exploration benefits from the phenomenon of quantum tunneling, where the system can overcome
energy barriers that might impede classical algorithms. The adiabatic theorem ensures that the system evolves
in a way that preserves its ground state, allowing it to settle into the optimal solution as the annealing progresses.
The ultimate outcome is obtained through measurement, revealing the state of the qubits and thus pro-
viding the solution to the encoded problem. Quantum annealing holds promise for addressing combinatorial
optimization problems, such as those encountered in logistics, finance, and artificial intelligence, where the sheer
3
1.3 Summary
complexity of potential solutions makes traditional computational methods less efficient. As quantum comput-
ing technologies advance, quantum annealing stands as a captivating avenue for exploring novel approaches to
problem-solving in diverse fields.
1.3 Summary
Our exploration of quantum computing has delved into the foundational principles of qubits, quantum cir-
cuits, and the distinctive model of adiabatic quantum computing. The adiabatic theorem’s guidance through time-
dependent Hamiltonians underscores the model’s potential as an alternative quantum computation paradigm.
The meticulous orchestration of encoding, preparation, annealing, and measurement within the adiabatic model
reflects its promise for efficient problem-solving. Additionally, our investigation into quantum annealing has
unveiled a powerful optimization technique, leveraging the unique attributes of qubits for complex problem
landscapes. Both adiabatic quantum computing and quantum annealing stand as promising frontiers in the
quantum computing landscape, offering innovative solutions to intricate problems as quantum technologies
continue to advance. The ability of quantum systems to explore multiple states simultaneously and overcome
classical computational constraints opens doors to transformative approaches in problem-solving across diverse
domains.
References
[1] Wittek, P. (2014). Quantum machine learning: what quantum computing means to data mining. Academic
Press.
[2] Prof.Andrew Childs - Lecture on the quantum adiabatic theorem -
https://www.cs.umd.edu/amchilds/teaching/w08/l18.pdf
[3] D. Aharonov, W. van Dam, J. Kempe, Z. Landau, S. Lloyd and O. Regev, Adiabatic quantum computation
is equivalent to standard quantum computation, 45th Annual IEEE Symposium on Foundations of Computer
Science, Rome, Italy, 2004, pp. 42-51, doi: 10.1109/FOCS.2004.8.
About the Author
Dr. Blesson George presently serves as an Assistant Professor of Physics at CMS College
Kottayam, Kerala. His research pursuits encompass the development of machine learning algorithms, along
with the utilization of machine learning techniques across diverse domains.
4
Multimodal NLP : Understanding the World
Like Us
by Jinsu Ann Mathew
airis4D, Vol.1, No.12, 2023
www.airis4d.com
Think about how we experience things - we see, hear, touch, smell, and taste. Just like that, Artificial
Intelligence (AI) is trying hard to understand the world just like we do with all our senses. This effort is called
multimodal Natural Language Processing (NLP), and its a really promising idea. Just like we use all our senses
at once, AI wants to do the same. It wants to combine information from what it sees, hears, and reads to
understand conversations better. This will make AI smarter and able to understand us better.
Imagine you’re trying to teach an AI to understand whats happening in a kitchen. Traditional AI might
focus only on pictures or only on written descriptions. Lets say you show it a picture of a pot on the stove.
Traditional AI might recognize the pot but struggle to understand if it’s boiling soup, making coffee, or just
sitting there.
Now, enter multimodal AI. Instead of just looking at the picture, it also reads the recipe text on the counter,
listens to the sizzling sounds, and maybe even detects the smell of spices in the air. It combines information
from the image, text, sound, and smell to get a fuller picture. This way, it can tell not only that there’s a pot on
the stove but also what’s cooking and how far along it is.
In simple terms, while traditional AI might focus on just one piece of the puzzle, like the picture, multimodal
AI brings together information from various sources, mimicking how we use multiple senses to understand our
surroundings. It’s like teaching AI to be more versatile and smarter, just like our own clever brains.
In this article, we explore the interesting world of multimodal NLP. We’ll see how AI tries to understand
things the way we do, using many senses at once.
2.1 What is Multimodal NLP?
Multimodal Natural Language Processing (NLP) is a field in artificial intelligence that focuses on under-
standing and processing language in conjunction with other types of information, or modalities, such as images,
audio, video, and more(Figure 1). In traditional NLP, the emphasis is mainly on working with text data, but
multimodal NLP broadens the scope to incorporate multiple sources of information. The goal of multimodal
NLP is to enable machines to comprehend and generate human language while considering the context provided
by different modalities. This approach reflects the way humans naturally interact with the world, using various
senses simultaneously.
2.2 Working of Multimodal AI
(image courtesy:https://www.kdnuggets.com/2023/03/multimodal-models-explained.html )
Figure 1: Multimodal learning
(image courtesy:https://www.analyticsvidhya.com/blog/2023/10/exploring-the-advanced-multi-modal-generative-ai/)
Figure 2: Modulus of multimodal Al
For instance, in a multimodal NLP system, understanding a description of a photo might involve not only
analyzing the text but also interpreting the visual content of the image. Similarly, when generating a description,
the system could produce both text and associated visual or auditory information.
The applications of multimodal NLP are diverse and include areas such as image captioning, video
analysis, interactive voice systems, and more. By combining language with other modalities, multimodal NLP
aims to create more robust and human-like interactions between machines and users, capturing the richness of
information available in different forms.
2.2 Working of Multimodal AI
Multimodal AI is crafted to understand and generate content across diverse data modes, including text,
images, and audio. This capability is facilitated through three essential modules: the Input Module, Fusion
Module, and Output Module (Figure 2) . Lets explore these modules to see how Multimodal AI does its job.
6
2.3 Input Module
2.3 Input Module
The input module in multimodal NLP acts as the eyes and ears of the artificial intelligence system. It’s the
starting point where the machine takes in information from various forms like written text, images, and audio
recordings. Just as our senses provide information about the world around us, the input module enables the
system to capture a broad range of data, setting the stage for a more comprehensive understanding.
For example, when analyzing a scene with text, images, and spoken words, the input module processes the
written information, recognizes visual elements in the images, and comprehends the spoken words. By handling
multiple modalities, the input module ensures that the AI system can grasp information in a way similar to how
humans use their senses to perceive the world.
2.4 Fusion Module
If the Input Module is like the senses, the Fusion Module is like the brain—it combines and processes
information from different sources.Once the information is gathered from different modalities, the fusion module
takes center stage. This crucial component is responsible for integrating the diverse data streams into a cohesive
representation.
Imagine you’re watching a video that includes spoken words, text on the screen, and images. The Fusion
Module takes all this information from the Input Module and blends it together. It might synchronize what’s
being said in the audio with the text on the screen and the visuals in the images.
There are different approaches to this fusion process.Three prominent techniques come into play here are:
2.4.1 Early Fusion:
In early fusion, information from different sources is combined right at the beginning of the system.
Imagine you have a video with spoken words, text on the screen, and images. In early fusion, these different
types of information are mixed together right from the start. For example, in our video scenario, early fusion
might involve merging the spoken words, text, and visual information at the initial stages of processing. This
combined information forms a unified representation that the system then uses to understand the content more
comprehensively. Early fusion is like cooking all the ingredients together from the beginning of a recipe.
It allows the system to consider the connections and relationships between different modalities right away,
providing a holistic view of the data.
2.4.2 Alignment-Based Fusion
Alignment-based fusion is a technique in multimodal processing where the system ensures that information
from different sources corresponds or aligns correctly. Suppose, you have a multimedia scenario with spoken
words, text, and images. In alignment-based fusion, the system pays special attention to aligning or synchronizing
these different modalities to ensure they match up accurately.
For example, if someone in a video is talking about a specific scene, the alignment-based fusion process
would synchronize the spoken words with the corresponding text on the screen and the relevant visuals in the
images. Its about making sure that the information from each modality lines up in a way that enhances the
overall understanding. Alignment-based fusion is like carefully arranging pieces of a puzzle to create a complete
picture. By ensuring proper alignment, the system can create a cohesive and accurate representation of the
multimodal data, allowing for a more nuanced and comprehensive understanding.
7
2.5 Output Module
2.4.3 Late Fusion
Late fusion is a technique in multimodal processing where information from different sources is combined
after each source has been processed individually. Its like combining different flavors after each one has been
fully developed. Here’s how it works: Consider a video with spoken words, text on the screen, and images. In
late fusion, each type of information is processed separately first. For example, the spoken words are understood
on their own, the text is analyzed independently, and the images are interpreted individually. After these
modalities have been fully processed, the system then combines the information. In our video scenario, late
fusion might involve integrating the fully processed spoken words, text, and visual information. This approach
allows the system to have a more detailed understanding of each modality before blending them together. Late
fusion is like adding distinct ingredients to a recipe one by one and then combining them at the end. By
processing each source independently before fusion, late fusion aims to capture the unique characteristics of
each modality, resulting in a richer and more nuanced representation of the overall data.
To sum it up, the Fusion Module is like the brain of the system. It mixes information from different sources,
making sure everything works together smoothly. Whether it combines things early on, lines them up perfectly,
or blends them late in the process, this module helps the system understand the world in a more detailed and
human-like way. Its like a conductor bringing together different instruments to create a beautiful tune, and
as technology gets better, improving how fusion works will make AI even smarter and more helpful in many
different areas.
2.5 Output Module
The Output Module in multimodal processing is like the voice or action of the artificial intelligence system.
Once the input data has been gathered and fused together, the Output Module steps in to generate meaningful
responses or actions. It takes the unified information and translates it into something understandable or useful.
For example, if you’re interacting with a virtual assistant, the Output Module might generate a text response to
your question, select an appropriate image, or even produce spoken words. Its the part that communicates the
system’s understanding or decision based on the processed information. The Output Module is crucial because
it turns the combined and processed data into a form that users can comprehend or interact with. It’s like the AI
system expressing itself in a way that makes sense to us, completing the cycle of understanding and interaction.
2.6 Conclusion
In conclusion, the fascinating world of Multimodal Natural Language Processing (NLP) opens new frontiers
in artificial intelligence, bringing us closer to machines that understand and interact with us in ways that mirror
our own multisensory experience. Through the input module, these systems capture information from diverse
sources like text, images, and audio, resembling our own way of perceiving the world through different senses.
The Fusion Module acts as the brain, skillfully blending these varied modalities through approaches like early
fusion, alignment-based fusion, and late fusion. This integration process allows AI systems to understand
small details and show a complete understanding of the information, kind of like how our brains handle details
from various places. Finally, the Output Module transforms this rich understanding into meaningful responses
or actions, completing the cycle of interaction. As technology continues to advance, refining multimodal
NLP techniques holds immense potential for creating more intelligent, versatile, and human-like AI systems.
In essence, the journey into multimodal NLP represents a significant stride toward machines that not only
8
2.6 Conclusion
understand but also engage with us in ways that align more closely with our own complex and dynamic ways of
communication.
References
Multimodal Deep Learning
Multimodal Deep Learning: Definition, Examples, Applications
A simple guide to multimodal machine learning
Exploring the Advanced Multi-Modal Generative AI
Multimodal Models Explained
Introduction to Multimodal Deep Learning
About the Author
Jinsu Ann Mathew is a research scholar in Natural Language Processing and Chemical Informatics.
Her interests include applying basic scientific research on computational linguistics, practical applications of
human language technology, and interdisciplinary work in computational physics.
9
Integrated Gradients: A Model
Interpretability Technique for Machine
Learning
by Linn Abraham
airis4D, Vol.1, No.12, 2023
www.airis4d.com
3.1 Introduction
In a previous article we saw why interpretable machine learning is important and a survey of the different
types of interpretability techniques. In this article we shall look into one specific technique called Integrated
Gradients [Sundararajan and Taly(2018)]. What is a problem that such techniques try to solve? Suppose we
have a model that has been trained to classify images correctly into one among several classes. Now given an
input image, the model might correctly predict it’s class or it might fail to. If it correctly predicts the class, we
could ask which of the pixels or group of pixels contributed the most to the model’s prediction. This is where
techniques such as Integrated Gradients come to play.
3.2 Applications
The integrated gradients technique can be applied to various types of neural networks. We show the
application to two image models.
3.2.1 Object Recognition Network
An object recognition network that uses a GoogleNet architecture and trained using data from ImageNet
challenge. A black image is used as a baseline and pixel importance is studied using the integrated gradients
technique. The gradients are computed for the output of the highest scoring class with respect to the input pixels
in each image. The results of the study are visualized in Figure. 1.
3.2.2 Diabetic Retinopathy Prediction
Diabetic Retinopathy is a condition that affects the eyesight in patients with diabetes. A deep neural
network has been used to predict the severity grade of the disease using retinal fundus images. The model has
achieved good results on various validation datasets.
3.2 Applications
Figure 1: Comparing integrated gradients with gradients at the image. Left-to-right: original input
image, label and softmax score for the highest scoring class, visualization of integrated gradients, visualization
of gradients*image. Notice that the visualizations obtained from integrated gradients are better at reflecting
distinctive features of the image.
11
3.3 Need for a Baseline
Trust in the networks predictions are important in areas such as health care and pixel attribution techniques
such as integrated gradients can help towards the goal. Figure 2 shows a visualization of integrated gradients
applied to the retinal fundus images. The aggregated gradients are overlayed on a grayscale version of the
image with positive attribution in the green color channel and negative attributions in the red color channel.
The resulting visualization shows a localization of the integrated gradient towards pixels that seem to be actual
lesions in the retina. Also the periphery of the lesion receives positive attribution whereas the interior of the
parts receive negative attribution. Showing that the network focuses on the boundary of the lesions.
Figure 2: Attribution for Diabetic Retinopathy grade prediction from a retinal fundus image. The original
image is show on the left, and the attributions (overlayed on the original image in gray scaee) is shown on the
right. On the original image we annotate lesions visible to a human, and confirm that the attributions indeed
point to them.
3.3 Need for a Baseline
It is common to reflect back on a life choice that you made and try to imagine how different your life
would have ended up, had your choice been a different one. Such thinking is what is called as a counterfactual
thinking. It is even said that the ability to think in counterfactual might be a uniquely human trait. When we
talk about the importance of a feature or pixel, we have in mind a situation where that feature or pixel is absent
which might lead to a better or worse off situation. A baseline image is useful when one needs to bring in
the concept of missingness of a particular feature. Note that when your input is an image, the features are the
individual pixel values in the image. If you remove a pixel from an image it might lead to several difficulties
like changing the shape of your data. Instead if you replace the actual pixel value with zero, you get a black
pixel. Then a pure black image can be considered as a baseline image for all the individual pixels in your input.
But surely such a black image is one among several baselines that can be considered. The impact of different
baselines other than a pure black image on attribution methods such as the integrated gradients are covered in
this article [Sturmfels et al.(2020)Sturmfels, Lundberg, and Lee].
12
3.4 Why not just use Gradients?
3.4 Why not just use Gradients?
Since the gradient of a function represents the direction of maximum increase of the function. The gradients
directly tell us which pixels have the greatest effect on the output. This was why gradients were often used
as a primitive method for such visualizations. However for neural networks the gradients of input pixels may
have small magnitudes around a sample even if the network depends heavily on those pixels. This is called
saturation and can happen when the output function flattens after a certain magnitude is reached for each pixel.
Imagine an image that is interpolated from a pure black image to the sample image. Intuitively this makes
sense, the pixels values immediately close to a given pixel should not change the output function significantly.
Additionally the authors of the main paper argue that gradients break the axiom of sensitivity that is required
for any good attribution technique.
3.5 Inspiration from Game Theory
The inspiration for the Integrated Gradients technique comes from Cooperative Game Theory, especially
the Aumann-Shapley cost-sharing method [Aumann and Shapley(1974)]. In games we have sets of participants
which may be called a coalition. The value of a participant or group of participant is computed by understanding
how much the value of the game is increased when the group of participants are added to any given coalition.
3.6 Evaluation of Attribution Techniques
How can we evaluate an attribution technique itself such as the Integrated Gradients? The authors of the
Integrated Gradients paper mention that every such method exisiting in literature had an issue. It could not
distinguish between artefacts that come from perturbing the data, a poor model and a poor attribution technique.
This was one of the motivations for them to come up with an axiomatic way to define a good attribution method.
3.7 Integrated Gradients
We can consider many paths of interpolating between a baseline and the given input image. Integrated
gradients aggregate gradients along the images that fall on the straight line between the baseline and the input.
The definition is shown in Figure. 3. Here α is the interpolation coefficient between 0 and 1 which is used to
Figure 3: Definition of integrated gradients
interpolate between the baseline and the given input image.x
i
is the given input image and x
i
is the baseline
image. There is still a lot of progress to be made in this area of path attibution methods and interpretablility
methods in general. Which leaves a lot of opportunities for young researchers. This is specifically useful in
research where the end goal is not just to develop an AI model that can make predictions but also help in filling
the gaps in theoretical understanding of various phenomenon.
13
REFERENCES
References
[Sundararajan and Taly(2018)] Mukund Sundararajan and Ankur Taly. A Note about: Local Explanation
Methods for Deep Neural Networks lack Sensitivity to Parameter Values, June 2018.
[Aumann and Shapley(1974)] Robert J. Aumann and Lloyd S. Shapley. Values of Non-Atomic Games. A Rand
Corporation Research Study. Princeton University Press, Princeton, N.J, 1974. ISBN 978-0-691-08103-8.
[Sturmfels et al.(2020)Sturmfels, Lundberg, and Lee] Pascal Sturmfels, Scott Lundberg, and Su-In Lee. Visu-
alizing the Impact of Feature Attribution Baselines. Distill, 5(1):10.23915/distill.00022, January 2020. ISSN
2476-0757. doi10.23915/distill.00022.
About the Author
Linn Abraham is a researcher in Physics, specializing in A.I. applications to astronomy. He is
currently involved in the development of CNN based Computer Vision tools for classifications of astronomical
sources from PanSTARRS optical images. He has used data from a several large astronomical surveys including
SDSS, CRTS, ZTF and PanSTARRS for his research.
14
Part II
Astronomy and Astrophysics
Black Hole Stories 5
Some Concepts in Einsteins General Theory
of Relativity
by Ajit Kembhavi
airis4D, Vol.1, No.12, 2023
www.airis4d.com
1.1 Introduction
In black hole stories-4 we considered the motion or particles around a gravitating object in the framework
of Newtons theory of gravitation. In this story we will describe some fundamental concepts of general relativity.
These are needed to understand the motion of particles and light rays around black holes, which we will describe
in the next story.
1.2 The Schwarzschild Metric
In the previous story we described the motion of a particle, with small mass m, around a much more
massive particle of mass M. This is like the motion of a planet around the Sun. Both particles were considered
to be point particles, or bodies whose size is very small compared to the distance between them. The more
massive particle can be treated as being at rest, with the smaller mass particle moving in the gravitational field
of the larger mass.
We will now consider the same situation, but now from the point of view of the general theory. The massive
particle is the source of the gravitational field. But unlike in Newtons theory, gravitation is no longer a force in
general relativity. The effect of M is to produce a curvature in the space-time structure around M, because of
which the trajectories of particles are different from what they would be in the absence of the gravitating mass
M. Our aim is to understand the nature of these trajectories and how they compare with the Newtonian situation.
In Newtons theory, we considered the classical equations of motion of particles in the gravitational field of
M. We used the conservation of energy and angular momentum to analyse the motion, without actually solving
any equations. In general relativity we have to take into account the curved space-time structure. For that, we
have to solve Einsteins equations to obtain a quantity known as the metric of space-time. The space-time around
the single point mass M we are considering is spherically symmetrical. The effect of M then depends only on
how far the particle is from M, and not on the angular position relative to M. The first ever exact solution of
Einsteins equations was for this spherically symmetric case; it was discovered by Karl Schwarzschild in 1916,
1.3 Geodesics
one year after Einstein announced his equations. The solution provides us the metric of the space-time, from
which all needed information about the space-time can be derived. We will describe below how given such a
space-time, the nature of particle orbits in it can be determined.
In classical mechanics, a spherically symmetric situation is best described in the spherical coordinates r,
θ, φ. Here r is the radial coordinate which measures the separation from the origin at which r=0, and θ, φ are
the usual angular coordinates. In this case, the radial coordinate r indicates distance from the centre. A small
change dθ in the angular coordinate corresponds to a displacement rdθ, while a change dφ in the φ coordinate
corresponds to a displacement rsinθdφ. The area of a sphere of radius r is 4πr
2
. A spherical coordinate system
is shown in Figure 1.
Figure 1: A spherical polar coordinate system. Diagram Courtesy Knowino Contributors
.
The situation is somewhat different for the Schwarzschild case, where again spherical polar coordinates r,
θ, φ are used. In this case a consequence of the space-time curvature is that r is no longer the distance from the
origin. And yet displacements corresponding to small changes dθ and dφ are again rdθ and rsinθdφ. How is
that possible? The reason is that the displacements correspond to small changes around a given point r, θ, φ,
while finite values of r are different from the actual distance from the origin. The distance, if needed, can be
calculated using the metric. Interestingly, the area of a sphere corresponding to r is again 4πr
2
.
17
1.3 Geodesics
1.3 Geodesics
According to Newtons first law of motion, a free particle, that is one which has no force acting on it,
moves in a straight line with a constant velocity. This is also true in Einsteins special theory of relativity.
When a force is present, there is deviation from a straight line. We have seen in story-4 how particle trajectories
are determined in classical mechanics when a gravitational force is present. The situation is quite different in
general relativity, where gravitation is identified with the structure of space-time, so gravity is always present.
A free particle in general relativity is one which has nothing except gravity affecting its motion. The trajectory
of such a particle is known as a geodesic.
The shape of a geodesic is quite different from that of straight line. As an example, let us consider the
surface of a sphere and any two points A and B on it, as shown in Figure 2. The shortest distance between the
two points, while remaining on the surface of the sphere, is the segment of a great circle which passes through
the two points. A great circle is a circle on the spherical surface which has the centre of the sphere as its own
centre. If we considered the situation in three dimensions, we could have drawn a straight line joining A and
B. But if we are restricted to remining on the curved surface, then the shortest distance is given by the segment
AB. In general relativity we are inescapably in a curved space-time. So we have to use geodesics.
Figure 2: A spherical surface with a great circle passing through points A and B. The great circle is a geodesic
for the spherical surface. The segment of the geodesic joining A and B is the shortest distance between them.
Image (Courtesy Vikas Mittal http://dx.doi.org/10.48550/arXiv.2209.04810 )
.
18
1.4 Types of Geodesics
How does one define a geodesic? In the type of geometry, known as Riemannian geometry, which
correspond to the space-time of general relativity, a geodesic can be defined as the curve of shortest distance
between two given points. The distance here is a 4-dimensional space-time analogue of the simple three
dimensional distance that we are used to. The distance can be determined once the metric of the space-time is
known. We will consider in the next story the geodesics of the Schwarzschild metric which correspond to the
trajectories of planets around the Sun.
1.4 Types of Geodesics
In special and general relativity, no particle can travel faster than light. This fundamental fact allows us to
define three types of geodesics: timelike, null and spacelike. Time like geodesics are those which correspond to
the trajectories of particles which move with speed less than the speed of light, like ordinary particles do. Null
geodesics correspond to particles which move with the speed of light. These necessarily have zero rest mass,
like photons which are particles of light. If neutrinos have zero rest mass they will move on null geodesics too,
but if they are massive they will move along time like geodesics. Spacelike geodesics correspond to trajectories
of particles which move faster than the speed of light. No such particles have so far been found, but there have
been some discussions about particles called tachyons which move faster than light.
In 4-dimensional space-time, the location of any event has 4 coordinates, three space coordinates describing
where an event has occurred, and a fourth time coordinate describing when it has occurred. For example a
ball could be thrown from a point on surface of the Earth at a time t
1
, which constitutes an event A. The ball
could be caught at another point at time t
2
later than t
1
, which constitutes event B. The events A and B have a
timelike separation since the ball travels from A to B at a speed which is evidently less than the speed of light.
If instead, A and B consisted of a beam of light being emitted at A and received at B, then the events A and B
have null separation. In both these cases event A can influence B, since a signal can be passed from A to B. But
suppose the distance between the events is such that not even a beam of light can travel from A to be in the time
t
2
-t
1.
Then the two events are said to have a spacelike separation. In such a case event A cannot influence event
B.
1.5 Conserved Quantities
In Story-4, we saw how in the classical case, the study of particle trajectories is significantly simplified
by using the conserved quantities of energy E and angular momentum L. With these quantities we could get
important insights into the trajectories without having to solve the differential equations of motion. We would
like to take a similar approach in general relativity, but for that we need to be able to define conserved quantities.
Because of the complexity of space-time curvature, it is not obvious how quantities like energy and angular
momentum are to be defined in the theory. But then Emmy Noether’s theorem comes to our rescue.
In classical mechanics, it is possible to define energy and angular momentum from elementary consider-
ations. But we described another route using Noether’s theorem, where a correspondence is set up between
conserved quantities and symmetries of the situation. Then energy conservation follows because the gravi-
tational field of a point particle is independent of time, and the conservations of angular momentum follows
from the spherical symmetry. It turns out that Noether’s theorem can be used in general relativity too. When
a symmetry is present, there is a corresponding quantity called a Killing vector. Each Killing vector allows a
conserved quantity to be defined.
19
1.5 Conserved Quantities
The Schwarzschild solution is independent of time, and has spherical symmetry, which leads to two Killing
vectors and two corresponding conserved quantities which we can call E and L. When the particle trajectory is
far from the centre, where the gravitational field is weak, the effect of space-time curvature is not important.
There E and L can be interpreted as energy and angular momentum respectively. When the particle is close
to the centre and space-time curvature is significant, E and L continue to be interpreted as energy and angular
momentum, in analogy to what happens at a great distance. But more than the meaning of these terms, the fact
that they are conserved is important.
We will see in the next story how the above fundamental considerations can be used to study particle
trajectories and how interesting the results are.
[Will continue..]
About the Author
Professor Ajit Kembhavi is an emeritus Professor at Inter University Centre for Astronomy and
Astrophysics and is also the Principal Investigator of the Pune Knowledge Cluster. He was the former director
of Inter University Centre for Astronomy and Astrophysics (IUCAA), Pune, and the International Astronomical
Union vice president. In collaboration with IUCAA, he pioneered astronomy outreach activities from the late
80s to promote astronomy research in Indian universities. The Speak with an Astronomer monthly interactive
program to answer questions based on his article will allow young enthusiasts to gain profound knowledge about
the topic.
20
Exploring the Enigmatic World of Be/X-ray
Binaries
by Sindhu G
airis4D, Vol.1, No.12, 2023
www.airis4d.com
2.1 Introduction
X-ray binaries, illustrated in Fig: 1, represent binary star systems where one of the stars, often a compact
object like a neutron star or a black hole, attracts and accumulates matter from its companion star. Among
the classifications of X-ray binaries, high-mass X-ray binaries hold a significant position. A high mass X-ray
binary (HMXB) is a specific kind of binary star system featuring a high-mass star (typically an O or B-type
star) paired with a compact object such as a neutron star or a black hole. These binary systems are identified
by their intense X-ray emissions, a consequence of the interaction between the massive star and the compact
object. Be/X-ray binaries emerge as a notable subtype within the category of high-mass X-ray binary systems.
Be/X-ray binaries are the most abundant type of massive X-ray binary systems in the Galaxy. This article delves
into the fascinating realm of Be/X-ray binaries, exploring the components, characteristics, and the scientific
significance of these captivating cosmic partnerships.
2.2 Understanding Be/X-ray Binaries
Be/X-ray binaries(Fig: 3) are a class of high-mass X-ray binaries.
2.2.1 The Components
Be/X-ray binaries consist of a Be star and a neutron star. Be stars typically belong to the O or B spectral
classes and are renowned for their strong stellar winds and the formation of circumstellar disks. Be stars,
characterised by their significant mass and high temperature, undergo rapid rotation. Be stars are known for
their emission lines arising from circumstellar disks composed of expelled material and gas. These circumstellar
disks play a crucial role in the dynamics of Be/X-ray binaries, influencing mass transfer and shaping the overall
behaviour of the binary system. Predominantly studied emission lines include those of hydrogen, such as the
Balmer and Paschen series, while Be stars may also display emission lines of helium and iron. In comparison to
B stars of the same optical spectral type, Be stars exhibit stronger infrared radiations, leading to the phenomenon
known as infrared excess. The mechanism behind the formation of such a circumstellar disk remains an open
question, generally attributed to the rapid rotation of Be stars. Given the extended semi-major axis of the
2.2 Understanding Be/X-ray Binaries
Figure 1: Artist’s conception of an X-ray binary system.[ Credit: NASA/GSFC ]
Figure 2: Classification of X-ray binaries[ Credit: Pablo Reig]
22
2.2 Understanding Be/X-ray Binaries
Figure 3: Sketch of a Be/X-ray binary system[ Credit: M. Orellana & G.E. Romero ]
orbital path in these sources, the volume of the companion star is notably smaller than that of the Roche lobe.
Consequently, due to the influence of the eccentric orbit, the compact star typically remains at a considerable
distance from the peripheral disk of the Be star, maintaining a relatively quiescent state for an extended duration.
The secondary star in the system is the neutron star, responsible for generating X-rays. Neutron stars,
originating from the collapse of massive star cores, are exceptionally dense and compact objects. These stars
possess robust magnetic fields and are capable of rapid rotation.Typically, the neutron star orbits the Be star in a
wide and highly elliptical path. The Be stars stellar wind gives rise to a disk, usually oriented differently from
the neutron stars orbital plane.
2.2.2 X-ray Emission
When the neutron star traverses the Be disk, it rapidly accumulates a substantial amount of gas. The
infalling gas onto the neutron star results in the observation of a luminous flare in hard X-rays. The gravitational
forces at play during the accretion process generate intense temperatures and pressures, causing the release of
X-rays. This phenomenon makes Be/X-ray binaries prominent X-ray sources in the sky. Observations in the
X-ray spectrum allow astronomers to study the properties and behaviour of these systems.
The occurrence of X-ray emission bursts in these sources is attributed to the interaction when the dense
companion star approaches the circumstellar disk of the Be star. During this interaction, the compact star
accretes matter characterised by low rotation speed and high density, a process that can also occur through
Roche lobe outflow. At this juncture, the brightness of the X-ray radiation near the hot point of the circumstellar
disk undergoes a significant increase, giving rise to bursts that endure for weeks to months, as depicted in Fig:
4.
2.2.3 Transient Astrophysical Phenomena
Be/X-ray binaries are known for their transient behaviour, characterised by unpredictable X-ray outbursts.
The transient astrophysical phenomena in Be/X-ray binaries are integral to understanding the dynamic nature of
these systems. The observed outbursts, accretion processes, and variations during periastron passages contribute
valuable data for researchers seeking to unravel the intricacies of mass transfer, disk dynamics, and the overall
23
2.3 Observational Techniques
Figure 4: Formation and evolution of compact stellar X-ray sources[ Credit: T. M. Tauris & E. P. J. van den
Heuvel ]
behaviour of Be/X-ray binaries.
2.3 Observational Techniques
Astronomers employ a variety of observational techniques to study Be/X-ray binaries. Observations in
X-rays, optical, IR and radio wavelengths provide a comprehensive understanding of the systems, allowing
scientists to piece together the puzzle of their characteristics and behaviours.
X-ray astronomy plays a pivotal role in the study of Be/X-ray binaries, where X-rays stand as the predominant
emission source. X-ray telescopes become indispensable tools for measuring the X-ray spectrum, flux, and
variability exhibited by Be/X-ray binaries. This data is instrumental in investigating the intricacies of the
accretion process and discerning the properties associated with the compact object.
Optical astronomy employs telescopes to scrutinise the Be star component within BeXRBs. This involves
measuring the star’s spectrum, luminosity, and variations in brightness. Additionally, optical spectroscopy is
utilised to examine the circumstellar disk surrounding the Be star.
The utilisation of radio telescopes enables the detection of radio emissions emanating from BeXRBs.
These emissions result from jets of material expelled from the accretion disk. Radio observations provide a
means to scrutinise the characteristics of both the jets and the accretion disk.
Infrared astronomy employs telescopes to examine the circumstellar disk surrounding the Be star. This
involves measuring the temperature, density, and dust content of the disk. Additionally, infrared observations
are instrumental in studying the mass loss rate from the Be star.
2.4 Importance of the Study of Be High-Mass X-ray Binaries
Be/X-ray binaries (BeXRBs) function as distinctive laboratories that explore extreme conditions in as-
trophysics. Comprising a Be star and a neutron star, these binaries offer unique opportunities to examine the
properties of matter under intense gravitational forces and magnetic fields.
These systems are known for their high variability across various time scales and wavelengths, providing
valuable insights into the dynamic behaviour of matter within them. The accretion of material from the Be
stars decretion disk onto the compact object, usually a neutron star, results in bright flares in hard X-rays. This
24
2.4 Importance of the Study of Be High-Mass X-ray Binaries
process not only sheds light on accretion physics but also contributes to our understanding of mass transfer
mechanisms in BeXRBs.
The neutron stars tidal force plays a crucial role in truncating the Be stars decretion disk, causing
equatorial disks in BeXRBs to be smaller and denser compared to those around isolated Be stars. Type I
outbursts, traditionally associated with eccentric binary orbits, have been proposed to occur in nearly circular
orbit Be/X-ray binaries due to the presence of the 3:1 Lindblad resonance within the Be star disk.
BeXRBs also serve as platforms for studying mass determination of the neutron star and the evolution of
its spin period. These investigations contribute to our broader understanding of the properties of neutron stars
and Be stars.
In summary, the significance of Be/X-ray binaries extends beyond their role as astronomical phenomena.
They act as crucial laboratories, offering insights into accretion processes, mass transfer dynamics, the effects of
tidal forces, and the intricacies of neutron star properties. As dynamic astrophysical systems, Be/X-ray binaries
contribute significantly to advancing our understanding of extreme conditions and fundamental processes in the
cosmos.
Various categories of Be X-ray binaries will be explored in the upcoming article.
References:
High-Mass X-ray binary: Classification, Formation, and Evolution
Optical/infrared observations unveiling the formation, nature and evolution of High-Mass X-ray Binaries
Be/X-ray binary
A catalogue of high-mass X-ray binaries in the Galaxy: from the INTEGRAL to the Gaia era
Be/X-Ray Binaries
Gamma-Ray Emission from Be/X-ray Binaries
Formation and evolution of compact stellar X-ray sources
About the Author
Sindhu G is a research scholar in Physics doing research in Astronomy & Astrophysics. Her research
mainly focuses on classification of variable stars using different machine learning algorithms. She is also doing
the period prediction of different types of variable stars, especially eclipsing binaries and on the study of optical
counterparts of x-ray binaries.
25
Part III
Biosciences
Exploring the Complexities of Ageing Process
with respect to Biological Age and
Chronological Age
by Geetha Paul
airis4D, Vol.1, No.12, 2023
www.airis4d.com
Image Courtesy: https://bioethics.hms.harvard.edu/journal/legal-age-change
1.1 Introduction
The concept of ageing can be approached through the lens of biological age and chronological age,
both of which are distinct ways to measure a persons age. Chronological age refers to the amount of time
elapsed from birth to a given date or it is a conventional measure based on the number of years lived, it is an
imperfect indicator of the ageing process. While biological age considers various biological and physiological
developmental factors, such as genetics, lifestyle, nutrition, and comorbidities. The unravelling of the biology
of senescence has enabled the identification of molecular markers of biological age, providing insights into
the cellular level of ageing. This article provides a conceptual overview of biological age, emphasising the
limitations of chronological age and the significance of biological age biomarkers in understanding the ageing
process. The distinction between chronological and biological age is crucial, as it has implications for health-
related outcomes and interventions aimed at extending healthspan and lifespan. As the mysteries of ageing are
being demystified, the potential to alter the course of someone’s lifespan and slow the pace of ageing is becoming
conceivable. This article highlights the importance of exploring the complexities of the ageing process through
the lens of biological and chronological age, shedding light on the potential for interventions and advancements
in understanding longevity and healthy ageing.
1.2 Telomere Shortening
Biological age is a comprehensive concept that is not only related to lifespan but also other health-related
outcomes, including quality of life. Therefore, biological age provides a more accurate assessment of the ageing
process compared to chronological age. Recent developments in epigenetics suggest that our epigenome might
be the key to understanding and calculating human biological ageing. This implies that it may soon be possible
to accurately calculate a person’s biological age. Currently, legal age always corresponds with chronological
age, but if a persons biological age turns out to be different, it raises the question of whether legal age should be
based on biological rather than chronological age. This distinction could have implications for how well people
function, as biological age is a better indication of a persons ability and well-functioning. The potential to
accurately calculate biological age based on epigenetic changes may lead to discussions about legal age change
and its alignment with biological rather than chronological age. The conventional view of ageing is that it is
a linear process of physical and cognitive decline that occurs over time as one progresses from adulthood into
senescence. The Ageing process can be defined by a progressive loss of complexity within the dynamics of
physiologic outputs (Lipsitz and Goldberger, 1992).
The ageing process is a multifactorial phenomenon that commences at the cellular level, leading to a gradual
decline in the body’s larger systems. Various theories, such as oxidative stress, mitochondrial dysfunction, cell
senescence, and telomere shortening, have been proposed to explain the ageing process. Genetic factors,
particularly telomere length, have been identified as potential ageing biomarkers.
1.2 Telomere Shortening
Telomeres, which are protective structures at the end of chromosomes, undergo shortening with age,
and this shortening rate may indicate the pace of ageing. Additionally, T-cell DNA rearrangement and DNA
methylation have been recognized as ageing biomarkers.
Image Courtesy: https://docs.google.com/document/d/1xRJb4w4FeuAMCUbSC9t4dSdr4MWeu5XWL-bAilDVVk8/edit
Figure 1: A process termed replicative senescence. (Hayflick and Moorhead, 1961; PMID: 13905658). Due
to signals derived from the trimming of the ends of chromosomes– called telomeres– that occurs with each
successive round of DNA duplication prior to cell division [(Bodnar AG, 1998; PMID 9454332),(Kuilman T
2010, PMID 21078816)
28
1.3 Epigenetic Regulation
1.3 Epigenetic Regulation
Epigenetic regulation is key to the normal development of an organism because it allows for modulating gene
expression levels through the addition of chemical modifications to the DNA and its associated histone proteins,
which are referred to as epigenetic marks. Cells of a multicellular organism are genetically homogeneous
but structurally and functionally heterogeneous owing to the differential expression of genes. Many of these
differences in gene expression arise during development and are subsequently retained through mitosis. Stable
alterations of this kind are said to be ’epigenetic’, because they are heritable in the short term but do not involve
mutations of the DNA itself. Research over the past few years has focused on two molecular mechanisms
that mediate epigenetic phenomena,DNA methylation and histone modifications. Epigenetic effects by means
of DNA methylation have an important role in development but can also arise stochastically as animals age.
Identification of proteins that mediate these effects has provided insight into this complex process and diseases
that occur when it is perturbed. External influences on epigenetic processes are seen in the effects of diet on
long-term diseases such as cancer. Thus, epigenetic mechanisms seem to allow an organism to respond to
the environment through changes in gene expression. The extent to which environmental effects can provoke
epigenetic responses represents an exciting area of future research.
Image Courtesy: https://www.mdpi.com/2073-4409/10/5/1074
Figure 2: Schematic of the mechanisms of epigenetic regulation. DNA methylation, histone modifications and
chromatin remodelling represent three different kinds of epigenetic mechanisms. Main players in the histone
modification machinery are depicted in the inset. Proteins that covalently attach chemical groups to the histone
tails are termed writers, whereas the so-called readers can recognize and bind to histone modifications. Enzymes
that remove histone marks are termed erasers. DNA methylation is found across different genomic elements. For
example, CpG islands, which are often found in the proximity of promoters, are usually depleted of methylation,
whereas gene bodies are heavily methylated. The chromatin structure is controlled by chromatin remodeler
complexes that use the hydrolysis of ATP to mediate the packaging of the chromatin.
1.4 DNA Methylation and Histone Modifications
DNA methylation, an epigenetic modification, has been found to play a significant role in modulating gene
expression and is associated with age-related pathologies such as cancer, osteoarthritis, and neurodegeneration.
Furthermore, DNA methylation biomarkers have been shown to determine the biological age of tissues across
the human lifespan and can estimate biological ageing rates. The potential of DNA methylation as a biological
biomarker for age assessment is being explored, and it is considered a promising avenue for understanding
29
1.5 CpG Islands
and addressing age-related pathologies. T-cell DNA rearrangement and DNA methylation play crucial roles
in T-cell development, differentiation, and function. DNA methylation and its enzymatic regulators direct
the development and differentiation of CD4+ and CD8+ T-cells. In T and B lymphocytes, demethylation at
specific loci has been associated with the transcription and rearrangement of immunoglobulin and TCR genes,
influencing cell function and survival. The epigenetic processes, including DNA methylation, regulate the
primary rearrangement of a single allele, impacting T-cell receptor gene assembly. These findings highlight
the significance of DNA methylation and T-cell DNA rearrangement in T-cell development, function, and
ageing-related pathologies.
DNA methylation is an epigenetic mechanism that involves the addition of a methyl group to the 5th
position of a cytosine in a CpG dinucleotide context. It is essential for mammalian development and gene
regulation. Key aspects of DNA methylation include: Gene Silencing: DNA methylation is mainly associated
with gene silencing, as it prevents proteins from binding to the methylated DNA. In the mammalian genome,
70-80% of CpG dinucleotides are methylated
1.5 CpG Islands
: CpG-rich sequences in promoter regions, referred to as CpG islands, usually lack DNA methylation. These
islands are crucial for stable gene expression and the regulation of imprinting. Gene Body Methylation: Methy-
lation of the gene body is associated with higher gene expression in dividing cells. DNA Methyltransferases
(DNMTs): These enzymes transfer a methyl group to the C5 position of cytosine, forming 5-methylcytosine.
The DNMT family includes DNMT1, DNMT2, and DNMT3. Demethylation: DNA methylation can be ac-
tively removed by members of the ten-eleven translocation (TET) enzyme family. These erasers mediate DNA
demethylation by oxidising 5-methylcytosine to 5-hydroxy-methylcytosine.
Image Courtesy: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10488447)
Figure 3: The effects of advancing age on the vasculature. Vascular ageing is characterised by arterial stiffness
and calcification. Arterial stiffness can induce an increase in vascular resistance and organ dysfunction. Arterial
calcification induced thrombotic events. A feed-forward loop exists between vascular ageing, hypertension, and
arterial stiffness.
30
1.6 Biomarkers of Biological Vascular Aging
(Image Courtesy: (https://academic.oup.com/lifemedi/advance-article/doi/10.1093/lifemedi/lnad033/7255917)
Figure 4: Shows the Biomarkers of Biological Vascular Aging
1.6 Biomarkers of Biological Vascular Aging
The consensus statement by the Aging Biomarker Consortium provides a comprehensive assessment
of biomarkers associated with vascular ageing (VA) and classifies them into three dimensions: functional,
structural, and humoral. The expert panel recommends clinically relevant VA biomarkers within each dimension,
including those reflecting vascular stiffness, endothelial function, vascular structure, microvascular structure,
distribution, and proinflammatory factors. The concept of biological age has been introduced as an integrated
measure reflecting the individualised ageing pace, emphasising the importance of identifying biomarkers that
outperform chronological age as determinants of morbidity and mortality. It proposes six pillars for ageing
biomarkers, including physiological characteristics, medical imaging, histological features, cellular alterations,
molecular changes, and secretory factors, to fulfil the requisites of assessing age-related changes, tracking the
physiological ageing process, and predicting the transition into a pathological status.
Some of the key biomarkers include: Pulse Wave Velocity (PWV)The: The most common measure of
arterial stiffness, PWV correlates with chronological age and is associated with an increased risk of CVD and
all-cause mortality Carotid Intima-Media Thickness (IMT): A measure of subclinical atherosclerosis, carotid
IMT increases with age and is associated with CVD morbidity and mortality. Coronary Artery Calcium Score
(CACS): A noninvasive measure of atherosclerosis, CACS is a powerful predictor of incident CVD and all-
cause mortality. Flow-Mediated Dilation (FMD): A measure of endothelial dysfunction, FMD decreases during
ageing and is an independent predictor of CVD outcomes. hs-CRP, Folic Acid, Homocysteine, and Fibrinogen:
These biomarkers have been associated with early vascular damage and are used to assess CVD risk.
Vascular ageing is characterised by the deposition of calcium phosphate crystals in both the arterial intima
(typically related to atherosclerosis) and the media (called M’nckeberg sclerosis). Both types of calcification
often develop in parallel and are not always easily distinguished by imaging techniques. Computed tomography
is the gold standard technique for quantification of coronary artery calcium score (CACS). Even though CACS
can be influenced by the presence of medial calcification, it is typically used as a surrogate marker for the extent
of atherosclerosis because it correlates well with coronary plaque burden. CACS correlates with chronological
age and is a powerful predictor of incident CVD and all-cause mortality.
31
1.7 Conclusion
(Image Courtesy: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10488447/)
Figure 5: Biomarkers for Vascular Aging Assessment
Vascular ageing is also characterised by atherosclerosis, which consists of lipid-rich plaque buildup in
the intima that can lead to acute myocardial infarction or stroke. Endothelial dysfunction, a major driver of
atherogenesis, can be measured by ultrasound as flow-mediated dilation, and flow-mediated dilation decreases
during ageing and is an independent predictor of CVD outcomes.
These biomarkers can provide valuable insights into the vascular ageing process and help identify individ-
uals at high risk of developing cardiovascular disease. However, further research is needed to establish their
clinical relevance and improve their accuracy in predicting and managing vascular ageing-related conditions.
1.7 Conclusion
Understanding the complexities of the ageing process through the lens of biological and chronological age,
as well as vascular age, sheds light on the potential for interventions and advancements in understanding longevity
and healthy ageing. The distinction between biological and chronological age, along with the identification
of biomarkers for vascular ageing, has implications for various aspects of life, including legal age change
and healthcare decisions. Recent developments in epigenetics suggest that the epigenome might be the key
to understanding and calculating human biological ageing, and advancements in understanding longevity and
healthy ageing are being made. The identification and utilisation of biomarkers for vascular ageing can improve
early detection of individuals at high risk of developing cardiovascular disease, and further research is needed to
establish their clinical relevance and improve their accuracy in predicting and managing vascular ageing-related
conditions.
References:
https://www.nature.com/articles/ng1089z
https://www.mdpi.com/2073-4409/10/5/1074
https://academic.oup.com/lifemedi/advance-article/doi/10.1093/lifemedi/lnad033/7255917
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8712891/
32
1.7 Conclusion
https://www.jacc.org/doi/10.1016/j.jacc.2019.11.062
Lipsitz LA, Goldberger AL. Loss of ‘complexity’ and ageing. Potential applications of fractals and chaos
theory to senescence. JAMA. 1992;267:1806–1809. [PubMed]
[Google Scholar]
Salih A, Nichols T, Szabo L, Petersen SE, Raisi-Estabragh Z. Conceptual Overview of Biological Age
Estimation. Ageing Dis. 2023 June 1;14(3):583-588. doi: 10.14336/AD.2022.1107.PMID:37191413; https:
//www.ncbi.nlm.nih.gov/pmc/articles/PMC10187689/
Ahadi, Sara, Wenyu Zhou, Sophia Miryam Schssler-Fiorenza Rose, M. Rexa Sailani, K vin Contrepois,
Monkia Avina, Melanie Ashland, Anne Brunet, and Michael Snyder. Personal ageing markers and ageo-
types revealed by deep longitudinal profiling. Nature Medicine 26 (2020): 83-90. https://doi.org/10.1038/
s41591-019-0719-5.
Sillanpaa, Elina, Miina Ollikainen, Jaakko Kaprio, Xiaoling Wang, Tuija Leskinen, Urho M. Kujala, and
Timo Trmkangas. Leisure-time physical activity and DNA methylation age—a twin study. Clinical Epigenetics
11, 1 (2019): 12. https://doi.org/10.1186/s13148-019-0613-5
About the Author
Geetha Paul is one of the directors of airis4D. She leads the Biosciences Division. Her research
interests extends from Cell & Molecular Biology to Environmental Sciences, Odonatology, and Aquatic Biology.
33
Part IV
General
Workaholism and Depression
by Ninan Sajeeth Philip
airis4D, Vol.1, No.12, 2023
www.airis4d.com
1.1 The Myths about Workaholism
Motivation is the guiding force of life. The less a person is self-motivated, the higher the chance for them
to go down the valley of depression. Self-motivation should not be mistaken for workaholism. Self-motivation
promotes hard work. The main difference between a hardworking person and a workaholic lies in the underlying
characteristics and the impact on their personal and professional lives. There are many simple and reliable
ways to distinguish the two. The central element is motivation itself. If your work makes you happier, it is
positive. On the other hand, it is something to be concerned about if it adds to stress and lack of confidence and
self-esteem. A healthy sense of self-worth and enjoyment in completing even small tasks are the most apparent
characteristics of a healthy individual.
In the modern world, where everything counts in reward, people opt for professions they are incapable of -
it could be peer or parental pressure. Though educated, many parents still mislead children from childhood to
achieve what they cannot and push them to the extremes of stress and obsessiveness with the consequence of
1.2 Fundamental Differences
depression and lack of self-worth.
Flexibility and adaptability to unexpected turnarounds are characteristic of a healthy mind. Failures are the
less-known side of success; nobody has achieved anything without facing failure. Occasional depressions are
also fine. It is a vent to exhaust emotions and to get back to routine. While the time and mode of overcoming
depressive stages vary between individuals, the concern is when it becomes obsessive or prolonged beyond
acceptable periods.
Another noticeable characteristic of workaholics is their withdrawal from social and community life.
They tend to be more self-centric, withdrawing themselves from public spaces and lacking the courage to
face the public. While environmental changes can trigger depression, it is more or less understood to have
genetic links that play a significant role in mood disorders and obsessive behaviour. One well-studied and
established association is the genetic link of Obsessive Compulsive Disorder (OCD), which is a pathway to
clinical depression. Clinical depression is the state in which an individual is feeling low and worthless for a
couple of weeks or more, highly irritable and fussy in their relationship with others.
On the other hand, hard workers are active in their public life, finding it easy to adapt to the situation and
make the best of it by living in the moment. Living in the moment is cultivated and cherished when one learns
to emphasise the importance of seeing opportunities in everything. The diversity in their interests makes them
unique and significantly affects their success. While workaholics pretend, hard workers get involved and adapt
to the environment, turning even disasters into opportunities.
1.2 Fundamental Differences
Health and well-being are yet another distinctive characteristic between hard workers and workaholics.
Workaholics are more likely to experience health issues due to their compulsive behavioural habits. In contrast,
hard workers burn out their excessive energy in activities that maintain the level of dopamine in their brains,
thereby continuing a balanced work-life. The passion and internal drive help them to focus on their goals to move
forward irrespective of the environmental or social campaigns. They may be concerned but are not affected
by how others judge or evaluate them to the extent that workaholics are. They can overcome social pressures
by deciding their goals, knowing the routes, and being prepared to take risks. On the other hand, workaholics
seek social validation and appreciation and push even to complete mundane tasks. In brief, the motivation for a
workaholic is external, while a hard worker’s inspiration is from within.
There are simple methods to identify and keep away from getting trapped in depression. The first and
foremost emphasis has to be on introspection. Introspection is to look back at yourself and ask simple questions
like whether what you are doing is stressful, resulting in low self-esteem and anxiety. Stress and hard work
are different, and one should see the difference. Hard work is essential for success and healthy self-esteem. I
remember the principal in college coming to our first day in the postgraduation class and saying, “I have nothing
more to offer you but two years of hard work and sweating!” That is a great offer I often share with my students.
Like the old saying “No crown without a cross”, hard work and success are synonyms, and one cannot earn one
without the other. Harworkers have sleepless nights and sweating days, but their passion or internal drive is the
key differentiating factor. If that is missing, it is time to rethink and turn away. While neurotransmitters like
serotonin cause the state of depression, exposure to stressful life, such as living in an abusive relationship or
prolonged exposure to stress at work, can catalyst the risk of depression.
36
1.3 Conclusion
1.3 Conclusion
Thomas Edison is known for his strong work ethic. He held 1093 patents in his industrial research
laboratory, mostly singlehandedly. Edison had a lot of critics at his time, and while most praised him, many
well-known scientists criticised him for the foolishness that is indicative of his ignorance of basic science.
However, Edison was willing to accept his fallacies and is said to have commented that he had made thousands
of discoveries of things that do not work before identifying what works. This is the attitude of a hard worker.
They see the brighter side of what the workaholic would blame as the cause of their depression and failure.
Reference
[1] 20 Differences between a workaholic and a hard worker - Managers Orbit https://www.managersorbit.
com/workaholic-vs-hard-worker/
[2] The Difference Between Hard Worker and Workaholic | Blog - Palmer Group https://www.thepalmergroup.
com/resources/blog/the-fine-line-between-hard-worker-and-workaholic
[3] Are You a Hard Worker or a Workaholic? - Inc. Magazine https://www.inc.com/carolyn-cutrone-the-difference-between-workaholic-and-hard-worker.
html
[4] How Being a Workaholic Differs from Working Long Hours and Why That Matters for Your Health -
Harvard Business Review https://hbr.org/2018/03/how-being-a-workaholic-differs-from-working-long-hours-and-why-that-matters-for-your-health
[5] Workaholism facts and statistics: everything you need to know - Clockify https://clockify.me/workaholism-facts
[6] 4 Famous Workaholics (And The Secrets of Their Success) - Lifehack https://www.lifehack.org/articles/
work/4-famous-workaholics-and-the-secrets-of-their-success.html
About the Author
Professor Ninan Sajeeth Philip is a Visiting Professor at the Inter-University Centre for Astronomy
and Astrophysics (IUCAA), Pune. He is also an Adjunct Professor of AI in Applied Medical Sciences [BCMCH,
Thiruvalla] and a Senior Advisor for the Pune Knowledge Cluster (PKC). He is the Dean and Director of airis4D
and has a teaching experience of 33+ years in Physics. His area of specialisation is AI and ML.
37
About airis4D
Artificial Intelligence Research and Intelligent Systems (airis4D) is an AI and Bio-sciences Research Centre.
The Centre aims to create new knowledge in the field of Space Science, Astronomy, Robotics, Agri Science,
Industry, and Biodiversity to bring Progress and Plenitude to the People and the Planet.
Vision
Humanity is in the 4th Industrial Revolution era, which operates on a cyber-physical production system. Cutting-
edge research and development in science and technology to create new knowledge and skills become the key to
the new world economy. Most of the resources for this goal can be harnessed by integrating biological systems
with intelligent computing systems offered by AI. The future survival of humans, animals, and the ecosystem
depends on how efficiently the realities and resources are responsibly used for abundance and wellness. Artificial
intelligence Research and Intelligent Systems pursue this vision and look for the best actions that ensure an
abundant environment and ecosystem for the planet and the people.
Mission Statement
The 4D in airis4D represents the mission to Dream, Design, Develop, and Deploy Knowledge with the fire of
commitment and dedication towards humanity and the ecosystem.
Dream
To promote the unlimited human potential to dream the impossible.
Design
To nurture the human capacity to articulate a dream and logically realise it.
Develop
To assist the talents to materialise a design into a product, a service, a knowledge that benefits the community
and the planet.
Deploy
To realise and educate humanity that a knowledge that is not deployed makes no difference by its absence.
Campus
Situated in a lush green village campus in Thelliyoor, Kerala, India, airis4D was established under the auspicious
of SEED Foundation (Susthiratha, Environment, Education Development Foundation) a not-for-profit company
for promoting Education, Research. Engineering, Biology, Development, etc.
The whole campus is powered by Solar power and has a rain harvesting facility to provide sufficient water supply
for up to three months of drought. The computing facility in the campus is accessible from anywhere through a
dedicated optical fibre internet connectivity 24×7.
There is a freshwater stream that originates from the nearby hills and flows through the middle of the campus.
The campus is a noted habitat for the biodiversity of tropical Fauna and Flora. airis4D carry out periodic and
systematic water quality and species diversity surveys in the region to ensure its richness. It is our pride that
the site has consistently been environment-friendly and rich in biodiversity. airis4D is also growing fruit plants
that can feed birds and provide water bodies to survive the drought.