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How do they work? Facebook X (Twitter) WhatsApp LinkedIn Pinterest Copy link A concise introduction to Markov chain models 20/03/25, 11:59 Last updated: Published: 09/03/24, 18:16 How do they work? Introduction A Markov chain is a stochastic process that models a system that transitions from one state to another, where the probability of the next state only depends on the current state and not on the previous history. For example, assuming that X 0 is the current state of a system or process, the probability of a state, X 1 , depends only on X 0 which is of course the current state of the system as stated. P ( X 1 ) = f ( P ( X 0 )) It may be hard to think of any real-life processes that follow this behaviour because there is the belief that all events happen in a sequence because of each other. Here are some examples: Games e.g. chess - If your king is in a certain spot on a chess board, there will be a maximum of 4 transition states that can be achieved that all depend on the initial position of chess piece. The parameters for the Markov model will obviously vary depending on your position on the board which is the essence of the Markov process. Genetics - The genetic code of an organism can be modelled as a Markov chain, where each nucleotide (A, C, G, or T) is a state, and the probability of the next nucleotide depends only on the current one. Text generation - Consider the current state as the most recent word. The transition states would be all possible words which could follow on from said word. Next word prediction algorithms can utilize a first-order Markov process to predict the next word in a sentence based on the most recent word. The text generation example is particularly interesting because only considering the previous word when trying to predict the next word sentence would lead to a very random sentence. That is where we can change things up using various mathematical techniques. k-Order Markov Chains (adding more steps) In a first-order Markov chain, we only consider the immediately preceding state to predict the next state. However, in k-order Markov chains, we broaden our perspective. Here’s how it works: Definition: a k-order Markov chain considers the previous states (or steps) when predicting the next state. It’s like looking further back in time to inform our predictions. Example: suppose we’re modelling the weather. In a first-order Markov chain, we’d only look at today’s weather to predict tomorrow’s weather. But in a second-order Markov chain, we’d consider both today’s and yesterday’s weather. Similarly, a third-order Markov chain would involve three days of historical data. By incorporating more context, k-order chains can capture longer-term dependencies and patterns. As k increases, the model becomes more complex, and we need more data to estimate transition probabilities accurately. See diagram below for a definition of higher order Markov chains. Markov chains for Natural Language Processing A Markov chain can generate text by using a dictionary of words as the states, and the frequency of words in a corpus of text as the transition probabilities. Given an input word, such as "How", the Markov chain can generate the next word, such as "to", by sampling from the probability distribution of words that follow "How" in the corpus. Then, the Markov chain can generate the next word, such as "use", by sampling from the probability distribution of words that follow "to" in the corpus. This process can be repeated until a desired length or end of sentence is reached. That is a basic example and for more complex NLP tasks we can employ more complex Markov models such as k-order, variable, n-gram or even hidden Markov models. Limitations of Markov models Markov models for tasks such as text generation will struggle because they are too simplistic to create text that is intelligent and sometimes even coherent. Here are some reasons why: Fixed Transition Probabilities: Markov models assume that transition probabilities are constant throughout. In reality, language is dynamic, and context can change rapidly. Fixed probabilities may not capture these nuances effectively. Local Dependencies: Markov chains have local dependencies, meaning they only consider a limited context (e.g., the previous word). They don’t capture long-range dependencies or global context. Limited Context Window: Markov models have a fixed context window (e.g., first-order, second order, etc.). If the context extends beyond this window, the model won’t capture it. Sparse Data : Markov models rely on observed data (transition frequencies) from the training corpus. If certain word combinations are rare or absent, the model struggles to estimate accurate probabilities. Lack of Learning: Markov models don’t learn from gradients or backpropagation. They’re based solely on observed statistics. Written by Temi Abbass Related articles: Latent space transformation s / Evolution of AI FURTHER READING 1. “Improving the Markov Chain Approach for Generating Text Used for…” : This work focuses on text generation using Markov chains. It highlights the chance based transition process and the representation of temporal patterns determined by probability over sample observations . 2 . “Synthetic Text Generation for Sentiment Analysis” : This paper discusses text generation using latent Dirichlet allocation (LDA) and a text generator based on Markov chain models. It explores approaches for generating synthetic text for sentiment analysis . 3. “A Systematic Review of Hidden Markov Models and Their Applications” : This review paper provides insights into HMMs, a statistical model designed using a Markov process with hidden states. It discusses their applications in various fields, including robotics, finance, social science, and ecological time series data analysis . Project Gallery

An individual may be restricted to a certain range of physical activities which they can participate in. Individuals are usually reliant on the surrounding environment and the maintenance of facilities. If they are not kept well maintained, individuals are usually discouraged. Go back Facebook X (Twitter) WhatsApp LinkedIn Pinterest Copy link Influence of different environmental factors on exercise Last updated: 30/01/25 Published: 10/02/23 The characteristics of environmental factors: - Chemical safety - Air pollution - Climate change and natural disasters - Diseases caused by microbes - Lack of access to health care - Infrastructure issues - Poor water quality - Global environmental issues What are the impacts of these environmental influences on physical activity? An individual may be restricted to a certain range of physical activities which they can participate in. Individuals are usually reliant on the surrounding environment and the maintenance of facilities. If they are not kept well maintained, individuals are usually discouraged. The physiological effect on training: Climate change will disproportionately affect the most vulnerable in our populations, including the very young, the very old, and those with pre-existing health conditions. Training adjustments to compensate for the influence of environmental factors on training: - Treatments for heat stress- stop exercising / move to a shaded or air-conditioned area / remove excess clothing or equipment / drink cold beverages / sit in front of a fan / put a cool piece of cloth around neck / place entire body in cool water e.g. cool bath or shower - Treatments for cold stress- move to a warm environment / remove cold and wet clothes / find access to warm air such as heaters, or fireplace / use electric or non-electric blankets / drink warm beverages Written by Kushwant Nathoo Related articles: Impacts of negligent exercise on physiology / Physical and mental health / Environmental impact of EVs

Common questions and answers- along with helpful resources- regarding the International Baccalaureate programme. International Baccalaureate (IB) Are you a student currently studying the IB Diploma Programme (IBDP), or about to commence it? You're in the right place! You may also like: Personal statements , A-level resources , University prep and Extra resources What is the IB? Jump to resources The IB is an International Academic Program which is another alternative to A levels. This is a highly academic program with final exams that prepare students for university and careers. You select one subject from each of the five categories, which include two languages, social sciences, experimental sciences, and mathematics. You must also choose either an arts subject from the sixth group or another from the first to fifth groups. How is the IB graded? Subjects might differ from schools and countries but these are the ideal subjects given in the IB. IB is graded through a point system (7 being the highest and 1 being the lowest) and the highest mark you can achieve in total is 45. For the 6 subjects you study you can achieve a maximum of 42 points. Theory of Knowledge and Extended Essay are combined to gain 3 extra bonus points. These 2 subjects will be marked from A (highest) to E (lowest) and then will be converted to points. What are the benefits of studying the IB? Even though there are a lot of subjects, this programme is great for students to gain new skills and be an all- rounder. IB also helps students to have a better idea of how work will be in university especially with coursework and that is one of the main things you will work on when studying IB- it is known as Internal Asssessment (IA). Doing CAS is also a great opportunity for students to be independent and find activities/ services to do outside of school to build up their portfolio on CAS as well as their CV/ personal statement when applying for university. The marking matrix used in the IB. How do universities use the IB to select students? All universities around the world accept the IB as a qualification gained in secondary school. Depending on the degree you are applying to, universities mainly focus on your Higher Level (HL) subjects. Each university has their own requirements for students applying to study a course at their institution. The most common way is considering your total point score out of 45, and your total point score of your HL subjects. Another way is asking applicants to achieve a certain grade in a particular grade at HL or at standard level (SL). If you complete the IB programme well enough, universities may prefer you over the other qualifications e.g. A-levels. Benefits of completing the IB programme. Resources for revision Websites to help Official IB website and the IB Bookshop Maths IA ideas Maths Analysis and Approaches SL and HL practice questions Maths resources in general / Worksheets and more Biology- BioNinja Biology, Chemistry, Physics, Maths- Revision Village / Save My Exams Biology, Chemistry, Maths- IB Dead IB Psychology IB Computer Science resources YouTube channels to help Chemistry- Richard Thornley Physics- Chris Doner Textbooks for both HL and SL Bio: Oxford IB Diploma Programme: Biology Course Biology for the IB Diploma by Brenda Walpole Chem: Chemistry Oxford IB Diploma Programme: Chemistry Course Chemistry for the IB Diploma Coursebook with Cambridge Elevate Enhanced Edition b y Steve Owen Physics: Physics Oxford IB Diploma Programme: Physics Course Physics for the IB Diploma with Cambridge by T. A. Tsokos Maths: Maths Oxford IB Diploma Programme- IB Mathematics: analysis and approaches / applications and interpretations

Pushing the boundaries of analytical chemistry Facebook X (Twitter) WhatsApp LinkedIn Pinterest Copy link Advances in mass spectrometry technology 08/07/25, 16:22 Last updated: Published: 09/06/24, 10:48 Pushing the boundaries of analytical chemistry In the rapidly evolving field of analytical chemistry, recent technological innovations in mass spectrometry have revolutionised the analysis and characterisation of molecules. These advancements, including high-resolution mass analysers, ion mobility spectrometry (IMS), and ambient ionisation techniques, are pushing the boundaries of what can be achieved in chemical analysis. Mass spectrometry is a powerful analytical technique that provides qualitative and quantitative information on an analyte. It is useful for measuring the mass-to-charge ratio (m/z) of one or more molecules present in a sample. The process consists of: Inlet - Allows the analyte to be connected to the mass spectrometre (MS). Could be direct inlet or gas chromotography (GC) / liquid chromatography (LC) to allow some separation before MS Ion source - Ensures that the analyte is ionised (i.e. carries a net charge) there are various types of ion sources depending on the analyte Analysers - Brings about a change in the velocity/trajectory of an ion from which the ions m/z can be determined i.e. characterises rate/velocity of ion. Multiple analysers are in tandem and different analysers can be combined to allow greater scope for analysis. A detection system is also required to amplify and measure ion signals. Analysers and detectors need to be held under low pressure - near vacuum. Detector - collects charge signals from ion beams. The computer then detects a spectrum. The electronic signals from the ions are then digitised to produce a mass spectrum of the analyte. High-resolution mass analysers One of the most significant breakthroughs in mass spectrometry is the development of high-resolution mass analysers. These instruments can differentiate between ions with extremely close mass-to-charge ratios, providing unprecedented levels of accuracy and specificity in compound identification. High-resolution mass spectrometry enables scientists to resolve complex mixtures and detect trace components with exceptional sensitivity, making it invaluable in fields such as metabolomics, environmental analysis, and drug discovery. Ion Mobility Spectrometry (IMS) Ion mobility spectrometry is another cutting-edge technology that enhances the capabilities of mass spectrometry. IMS separates ions based on their size, shape, and charge in the gas phase, providing an additional dimension of separation before mass analysis. This technique improves the resolution of complex samples, particularly for isomeric compounds that are challenging to distinguish using conventional methods. IMS coupled with mass spectrometry is widely applied in metabolomics, proteomics, and lipidomics research, enabling deeper insights into molecular structures and interactions. Ambient ionisation techniques Traditional mass spectrometry methods often require extensive sample preparation and ionisation processes in controlled laboratory environments. Ambient ionisation techniques have transformed this paradigm by enabling direct analysis of samples in their native states, including solids, liquids, and gases, without prior extraction or purification steps. Techniques such as desorption electrospray ionisation (DESI) and direct analysis in real-time (DART) have expanded the scope of mass spectrometry applications to fields like clinical diagnostics, food safety, and forensic analysis. Ambient ionisation allows for rapid, on-site measurements with minimal sample handling, revolutionising point-of-care testing and field analysis. In conclusion, the continuous evolution of mass spectrometry technology is reshaping the landscape of analytical chemistry. These innovations not only empower researchers to explore new realms of chemical analysis but also facilitate applications in areas such as precision medicine, environmental monitoring, and materials science. As these technologies continue to advance, the future holds even greater promise for pushing the boundaries of analytical chemistry and unlocking the mysteries of the molecular world. Written by Anam Ahmed Related article: Advancements in semi-conductor manufacturing Project Gallery

Explore artificial intelligence, a technology that has taken the world by storm. Learn how it is used in fields like agriculture, drug discovery, and outer space. Elsewhere, get to grips with semi-conductor manufacturing, quantum computing, and biotechnology. Technology Articles Explore artificial intelligence, a technology that has taken the world by storm. Learn how it is used in fields like agriculture, drug discovery, and outer space. Elsewhere, get to grips with semi-conductor manufacturing, quantum computing, and biotechnology. You may also like: Maths , Physics , Engineering Fake science websites Ways fake science websites misinform and misguide readers The evolution of artificial intelligence And its greater role in natural language processor technologies Medical biotechnology Technology in the medical sciences Quantum computing What are its applications? Improving agriculture Revolutionising sustainable agriculture through AI AI in drug discovery Using this technology in drug research Digital disinformation With the use of IT cells Digital innovation in rural farming What are the benefits? AI in space What is artificial intelligence used for in outer space? Radiation therapy to treat cancer Revolutionising patient setup in cancer treatment AI: the good, the bad, and the future A Scientia News Biology group collaboration Photonic integration In semiconductor manufacturing Nanomedicine Tiny solutions for big health problems NHS clinical computer scientist Exploring the day-to-day routine in this new field in healthcare Semi-conductor laser technology The recent advancements Code to cure How bioinformatics and technology helped to develop a vaccine for COVID-19 Virtual reality in healthcare Its potential Mauritius's rise as African leader of mobile networks An in-depth look at the rollout of 5G on the island, and the factors enabling this

In today's fast-paced and often overwhelming world, taking care of our mental well-being is more crucial than ever. In this article, we will explore practical strategies that can easily be incorporated into our day-to-day lives, allowing us to establish a solid foundation for our mental well-being and sustain it in the long run. Go Back Facebook X (Twitter) WhatsApp LinkedIn Pinterest Copy link Empowering your mental health journey with practical strategies Last updated: 22/05/25 Published: 18/05/23 In today's fast-paced and often overwhelming world, taking care of our mental well-being is more crucial than ever. In this article, we will explore practical strategies that can easily be incorporated into our day-to-day lives, allowing us to establish a solid foundation for our mental well-being and sustain it in the long run. 1. Embracing mindfulness Mindfulness is a powerful practice that helps us stay present, cultivate awareness, and manage stress. Imagine starting your day by dedicating a few minutes to mindful breathing or meditation, allowing yourself to set a calm and focused tone for the day. Engage in activities with a mindful mindset, whether it's taking a peaceful walk in nature, relishing a cup of tea, or fully immersing yourself in the present moment. 2. Exercise Physical activity is another essential self-care strategy that not only benefits our physical health but also plays a profound role in nurturing our mental well-being. Find an exercise routine that that brings you joy and that easily fits into your life. Whether it's walking, jogging, yoga, or any other form of movement that resonates with you, the key is to find something you enjoy and can stick to. Even small bursts of exercise throughout the day, like a short walk during your lunch break or opting for the stairs instead of the elevator, can make a significant difference in your overall well-being. 3. Sleep Hygiene Adequate sleep is vital for mental and emotional wellbeing. Establishing good sleep hygiene is crucial. Maintain a consistent sleep schedule by going to bed and waking up at the same time each day. Create a relaxing bedtime routine that signals to your body that it's time to unwind. Consider reading a book, taking a warm bath, or practicing gentle stretches to prepare your mind and body for restful sleep. Ensure your bedroom provides an optimal sleep environment by keeping it dark, quiet, and cool, and minimize exposure to screens before bed. 4. Online mental health platforms In our digital age, online mental health platforms have become invaluable resources for supporting our mental well-being. Platforms like Headspace , Better Help , and Calm offer a range of services, including meditation exercises, therapy sessions with licensed professionals, and stress reduction tools. Exploring these platforms can provide the support and guidance needed on your mental health journey. Self-care apps that can be installed on phones Prioritising self-care is essential for maintaining good mental health. By incorporating these practices into your daily routine, you can nurture your mind, body, and soul. By investing time and energy into yourself, you are fostering a stronger foundation for a happier and healthier life. Written by Viviana Greco Related articles: Physical and mental health / Imposter syndrome in STEM / Mental health in the South Asian community

Study the plethora of interactions between drug and target with these articles focusing on antibiotic resistance, analgesics, and drug treatments for diseases with presently no cure. Pharmacology Articles Study the plethora of interactions between drug and target with these articles focusing on antibiotic resistance, analgesics, and drug treatments for diseases with presently no cure. You may also like: Chemistry , Medicine Effect of heat on medicine When medication is exposed to extreme heat, what happens? Antibiotic resistance Its rising threat Exploring ibuprofen Ibuprofen is a painkiller A treatment for Parkinson's disease By using a common diabetes drug mRNA vaccines What they are, and how they are different to traditional (live, attenuated, or viral-vectored) vaccines Anthrax toxin Using bacterial toxins to treat pain 'The Molecule': an upcoming biotech thriller A book review

Exploring the microscopic world of molecules Facebook X (Twitter) WhatsApp LinkedIn Pinterest Copy link Quantum Chemistry Last updated: 24/02/25, 11:29 Published: 06/02/25, 08:00 Exploring the microscopic world of molecules Quantum chemistry provides a glimpse into the strange and fascinating world of molecules and atoms, where the principles of traditional chemistry and physics no longer apply. While classical chemistry can explain molecular interactions and bonding, it cannot fully account for particles' unusual, frequently contradictory behaviour at the atomic and subatomic levels. Quantum mechanics provides scientists with a powerful framework for understanding the complicated behaviour of electrons and nuclei in molecules. The basics of quantum chemistry The notion of wave-particle duality, which states that particles, such as electrons, act not just like objects with mass but also like waves, is central to quantum chemistry. Because the exact position and momentum of an electron cannot be known at the same time (according to the Heisenberg Uncertainty Principle), probability distributions are used to describe electrons rather than accurate orbits. These distributions are represented by mathematical functions known as wave functions, which describe the probability of finding an electron in a specific location surrounding the nucleus. This fundamentally affects our understanding of chemical bonding. Instead of conceiving a bond as a solid connection between two atoms, quantum chemistry defines it as the overlap of electron wave functions, which can result in a variety of molecular topologies depending on their energy levels. Quantum mechanics and bonding theories Quantum mechanics has fundamentally altered our knowledge of chemical bonding. The classic Lewis structure model, which explains bonding as the sharing or transfer of electrons, is effective for simple molecules but fails to convey the complexities of real-world interactions. In contrast, quantum chemistry introduces the concept of molecular orbitals. In molecular orbital theory, electrons are not limited to individual atoms but can spread across a molecule in molecular orbitals, which are combinations of atomic orbitals from the participating atoms. These molecular orbitals provide a more detailed explanation for bonding, especially in compounds that do not match simple bonding models, such as delocalised systems like benzene or metals. For example, quantum chemistry explains why oxygen is paramagnetic (it possesses unpaired electrons), a characteristic that classical bonding theories cannot explain. Quantum chemistry and quantum computing One of the most interesting frontiers in quantum chemistry is its application to the development of quantum computers. Traditional computers, despite their enormous processing power, struggle to model the complicated behaviour of molecules, particularly large ones. This is because simulating molecules at the quantum level necessitates tracking all conceivable interactions between electrons and nuclei, which can quickly become computationally challenging. Quantum computers use fundamentally different ideas. They employ qubits, which, unlike classical bits, can exist in a state of both 0 and 1. This enables quantum computers to execute several calculations concurrently and manage the complexity of molecular systems considerably more effectively. This could lead to advancements in quantum chemistry, such as drug discovery, where precisely modelling molecular interactions is critical. Instead of depending on trial and error, scientists may utilise quantum computers to model how possible pharmaceuticals interact with biological molecules at the atomic level, thereby speeding up the creation of novel therapies. Similarly, quantum chemistry could help in the development of novel materials with desirable qualities, such as stronger alloys and more efficient energy storage devices. Why quantum chemistry matters The consequences of quantum chemistry go well beyond the lab. Understanding molecular behaviour at its most fundamental level allows us to create new technologies and materials that have an impact on everyday life. Nanotechnology, for example, relies largely on quantum principles to generate innovative materials with applications in medicine, electronics, and clean energy. Catalysis, the technique of speeding up reactions, also benefits from quantum chemistry insights, making industrial operations more efficient, such as cleaner fuel generation and more effective environmental remediation. Furthermore, quantum chemistry provides insights into biological processes. Enzymes, the proteins that catalyse processes in living organisms, work with a precision that frequently defies standard chemistry. Tunnelling, quantum phenomena in which particles slip past energy barriers, helps to explain these extraordinarily efficient biological processes. In brief, quantum chemistry provides the fundamental understanding required to push the limits of chemistry and physics by exposing how molecules interact and react in ways that traditional theories cannot fully explain. Quantum chemistry has the potential to radically alter our understanding of the microscopic world, whether through theoretical models, practical applications, or future technology advancements. Written by Laura K Related articles: Quantum computing / Topology Project Gallery

What is it and what does it do? Facebook X (Twitter) WhatsApp LinkedIn Pinterest Copy link The role of dopamine in the movement and the reward pathway 14/07/25, 15:01 Last updated: Published: 21/09/24, 15:59 What is it and what does it do? Dopamine is a neurotransmitter produced mainly in the ventral tegmental area (VTA) and the substantia nigra pars compacta (SNPC) in the brain, exhibiting both excitatory and inhibitory effects in different brain pathways. Dopamine is important in mediating the mesolimbic and nigrostriatal pathways for reward and movement, respectively. Therefore, damage to dopaminergic neurones affects dopamine levels in the brain and can consequently result in diseases associated with abnormal dopamine levels. Movement The role of dopamine is vital in modulating the initiation of movement through both the direct and indirect pathways of the basal ganglia ( Figure 1 ). In the direct pathway, dopamine produced from the SNPC binds to the D1 Gs-coupled receptors in the striatum resulting in the activation of the intracellular signalling cascade. Activation of these receptors results in increased intracellular cyclic adenosine monophosphate (cAMP) and protein kinase A (PKA) levels, which control the modulation of ion channels, including calcium channels for further depolarisation of the striatal cells. The excitation of the striatum results in GABAergic inhibition of the globus pallidus internal segment (GPI) and the substantia nigra pars reticulata (SNPR). Hence, this results in the disinhibition of the thalamus, allowing for excitatory glutamatergic transmission to the motor cortex for the facilitation of movement. The activation of the striatum via D1 receptor stimulation can be supported by a study conducted by Gerfen et al. 2012 in which they concluded that PKA activates calcium voltage-gated 1 L-type calcium channels, resulting in depolarisation of striatal cells, which causes the enablement of movement via the direct pathway. However, in the indirect pathway, dopamine binds to D2 Gi-coupled receptors with a higher affinity than D1 receptors, causing inhibition of these receptors and their intracellular signalling cascades. Consequently, there is decreased inhibition of potassium channels by the second messengers, resulting in hyperpolarisation due to potassium efflux from the striatal cells. As the striatum is inactivated, this reduces the overall inhibitory effect of the indirect pathway on the thalamus, allowing for movement. Therefore, dopamine is critical for the normal functioning of humans by allowing them to control their movements for survival, for example, by pushing a ball away when it is about to hit them. Reward pathway The mesolimbic dopaminergic pathway ( Figure 2 ) is the most recognised reward pathway in the brain. This pathway contains the VTA, located in the midbrain, the nucleus accumbens (NA) and the tuberculum olfactorium (TO), located in the basal forebrain. The lateral regions of the VTA are the most abundant in A10 dopaminergic neurones in comparison to other regions of the VTA. These A10 neurones are activated in association with reward anticipation, for example, after exercising. The medial VTA dopaminergic neurones project to the core and medial shell regions of the NA, and the lateral VTA project towards the lateral shell region of the NA (figure 3). Thus, increasing dopamine levels in the NA and inducing the processing of the reward. Moreover, dopaminergic inputs from the VTA to the TO allow the individual to develop an odour preference for a specific stimulus due to motivation-oriented behaviour. Hence, this could be a reason why the anticipation of eating one's favourite food by evoking the memory of its smell is associated with the feeling of reward. Experiments conducted by FitzGerald et al. 2014 support my points regarding the role of the TO in the mesolimbic pathway. In their study, mice were given a choice of two different odours to choose from. The team noted activation of c-Fos neurones in the forebrain, indicating neuronal activity in this region, which is involved in reward motivation behaviour. Hence, allowing them to support the importance of the TO in odour processing and reward behaviour in the mice when choosing a more pleasurable odour. Eventually, projections from the TO and NA converge at the ventral pallidum, where the enrichment of reward-related learning occurs. Therefore, dopamine is essential for the initiation of the reward pathway in ensuring the continuation of reward behaviour when exposed to a specific stimulus and for survival due to the association of reproduction with reward. Conclusion In conclusion, dopamine is essential for the initiation of movement and in the reward pathway for normal human functioning and survival. Studies into aldehyde-dehydrogenase 1 in the SNPC have found that it protects dopaminergic neurones against neurodegeneration. Further studies will aid in understanding the mechanisms by which this enzyme is regulated and the actions by which it protects dopaminergic neurones in the SNPC. Written by Maria Z Kahloon Related articles: The dopamine connection between the gut and the brain / Interplay of hormones and microbiome / Types of movement Project Gallery

To begin, there was the Humoral Theory, which looked at how disease was caused by gaps in fluids/humours which were: blood, yellow bile, black bile and phlegm, which equated to the elements of air, fire, earth and water respectively. The imbalance can come from habits like overeating Go back Facebook X (Twitter) WhatsApp LinkedIn Pinterest Copy link Key historical events and theories in public health Last updated: 17/11/24 Published: 10/02/23 Introduction Now more than ever, public health has become crucial, which looks at promoting health and preventing disease within a society. There have been numerous events and concepts that have helped shape our current health systems today because without them, it is possible that our health systems would not have advanced without previous knowledge to evolve from. This article will focus on certain key events and concepts. Humoral Theory (Ancient Greek and Roman times) To begin, there was the Humoral Theory, which looked at how disease was caused by gaps in fluids/humours which were: blood, yellow bile, black bile and phlegm, which equated to the elements of air, fire, earth and water respectively. The imbalance can come from habits like overeating and too little/much exercise or external factors such as the weather. This theory was thought to have originated from the Hippocratic Corpus, a compilation of 60 medical documents written during the Ancient Greek era by Hippocrates. Although this theory as we know now is flawed, it did provide a foundational understanding of the human body and was utilised in public health for centuries before being subsequently discredited for the Germ Theory established during the mid-19th century. Miasma Theory (Ancient Greek era to the 19th century) Another theory replaced by Germ Theory was the Miasma theory, which stated that diseases like the plague and cholera were spread due to toxic vapours from the ground/decomposing matter. This theory along with the Humoral theory was accepted for thousands of years since the Ancient Greek era. With regards to the cholera outbreaks in the Victorian era, John Snow’s theory of polluted water causing cholera was initially not accepted by the scientific community during his death in 1858. Eventually though, his theory became accepted when Joseph Bazalgette worked to fix London’s sewage to prevent more deaths by cholera. This event with the Germ Theory led to Miasma and Humoral theories to be disproved, although they provided foundational understanding of how diseases spread. The discovery of vaccines (late 18th century) Aside from theories such as the four humors from above, there were concepts or discoveries that advanced public health measures such as vaccination, which eradicated smallpox and is still used today to prevent the severity of diseases such as COVID-19, influenza and polio. The origins of successful vaccines could be traced back to Edward Jenner who in 1796, retrieved samples from cowpox lesions from a milkmaid because he noticed that contracting cowpox protected against smallpox. With this in mind, he inoculated an 8 year old boy and after this, the boy developed mild symptoms, but then became better. Without this event, it is likely that the human population would significantly decrease as there is more vulnerability to infectious diseases and public health systems being weaker or less stable. Image of a COVID-19 injection. Germ Theory (19th century) As for current scientific theories relating to public health, there is the widely accepted Germ Theory by Robert Koch during the 19th century in the 1860s, stating that microorganisms can cause diseases. He established this theory by looking at cow’s blood through a microscope to see that they died from anthrax and observed rod-shaped bacteria with his hypothesis that they caused anthrax. To test this, he infected mice with blood from the cows and the mice also developed anthrax. After these tests, he developed postulates and even though there are limitations to his postulates at the time like not taking into account prions or that certain bacteria do not satisfy the postulates, they are vital to the field of microbiology, in turn making them important to public health. The establishment of modern epidemiology (19th century) Another key concept for public health is epidemiology, which is the study of the factors as well as distribution of chronic and infectious diseases within populations. One of epidemiology’s key figures is John Snow, who explored the cholera epidemics in London 1854, where he discovered that contaminated water from specific water pumps was the source of the outbreaks. Moreover, John Snow’s work on cholera earned him the title of the “father of modern epidemiology” along with his work providing a basic understanding of cholera. Therefore, this event among others has paved the way for health systems to become more robust in controlling outbreaks such as influenza and measles. Conclusion Looking at the key events above, it is evident that each of them has played an essential role in building the public health systems today through the contributions of the scientists. However, public health, like any other science, is constantly evolving and there are still more future advancements to look forward to that can increase health knowledge. Written by Sam Jarada Related articles: Are pandemics becoming less severe? / Rare zoonotic diseases / How bioinformatics helped with COVID-19 vaccines REFERENCES Lagay F. The Legacy of Humoral Medicine. AMA Journal of Ethics. 2002 Jul 1;4(7). Earle R. Humoralism and the colonial body. Earle R, editor. Cambridge University Press. Cambridge: Cambridge University Press; 2012. Halliday S. Death and miasma in Victorian London: an obstinate belief. BMJ. 2001 Dec 22;323(7327):1469–71. Riedel S. Edward Jenner and the history of smallpox and vaccination. Proceedings (Baylor University Medical Center). 2005 Jan 18;18(1):21. National Research Council (US) Committee to Update Science, Medicine, and Animals. A Theory of Germs. Nih.gov. National Academies Press (US); 2017. Sagar Aryal. Robert Koch and Koch’s Postulates. Microbiology Notes. 2022. Tulchinsky TH. John Snow, Cholera, the Broad Street Pump; Waterborne Diseases Then and Now. National Library of Medicine. Elsevier; 2018. p. 77–99.