Are you hungry?

Written in 1890 "Hunger"  is a rather difficult  novel by Norwegian Nobel laureate  Knut Hamsun.   The novel carries autobiographical overtones    of a starving individual and sketches his physical and mental trauma. Hunger is an existential necessity  contrived by evolution  and  compels organisms to seek food to survive. That physiologically  complex  parallel and interwoven  pathways  reinforce hunger underscores it significance.    History is replete with instances when  severe famine has driven  societies  to consume things they normally would have absolutely avoided.

Physiologically, hunger is an homeostatic signal for energy. Homeostasis is the process  of maintaining a stable, balanced internal environment for a living system   to function correctly.  From single-celled organisms to complex multicellular beings like humans, all living systems require this internal balance for survival.    Built-in system of checks and balances ensure stable internal conditions like temperature, blood pH, and glucose levels etc. Body achieves this  through constant monitoring,  corrective signals and prompt remedial actions.  For example we feel hungry when energy level goes down,  thirsty  when  hydromineral balance is disturbed,  we shiver  when body feels cold......Primitive man lived on a feast-fast cycle, alternating between massive gorging after a successful hunt followed by  involuntary fasting during periods of food scarcity.

Potato Eaters by van Gogh

At the biochemical level, homeostatic  hunger and its alleviation is an intricate multi hormonal, multi enzymatic process   with  hypothalamus calling the crucial  shots.   In this multistarrer drama  three hormones play vital roles:   , the hunger hormone ghrelin  and the  satiety hormones GLP-1 and  leptin.  When energy level is low,  ghrelin  secreted by empty stomach talks to hypothalamus via the gut-brain axis and  stimulates  hunger. Though labelled hunger hormone, this   small peptide of 28 aminoacids   is a very busy molecule as it  is associated with  learning, memory, mood swings,  sleep-wake cycle etc.  With food intake  ghrelin levels drop ,  glucose level in the blood goes up and   GLP-1 secreted by the intestines  instructs pancreas to release insulin. When sufficient fast is stored  leptin, secreted by adipose tissues  contacts hypothalamus to stimulate a feeling of fullness.  There needs to be a fine balance between the hunger hormone and the satiety hormones.   Any small error anywhere in this complex biochemical process can lead to a host of pathophysiological conditions including anorexia, hyperphagia, obesity or Type 2 diabetes mellitus etc.    Metabolites  released by gut microbes too  influence  appetite hormones, and communicate  with the brain via the vagus nerve.  During those times, when body needs energy and food is unavailable, body first   exhausts the glucose stock  and then  easily switches to  burning  fat reserves.

Though we might still retain some elements of the  feasting- fasting  program within us,   with easy availability of food  we   have  settled for  Breakfast-Lunch-Dinner routine whether hungry or not.    We have also discovered the pleasure of eating and thus  succumbed  to hedonic hunger.     Also called hyperphagia,  hedonic hunger   can be triggered by a variety of confusing and contradictory cues.   For example we eat when we feel happy,  we also eat to drown our sorrow.   We eat when excited, also when  bored.  Some people eat  when  over stressed  while others eat when relaxed.   Even after a full meal,  sensory stimuli such as  sight, smell or just thought of tasty food  can work up our appetite. Surprisingly  the neurocircuits for homeostatic  and hedonic hunger   overlap and ghrelin is implicated in both.   Ghrelin can  influence brain's reward pathways, and spike the release of dopamine, the "feel good molecule".  The hedonic urge  is powerful enough to  override  the  homeostatic signals of satiety.  Precisely for this reason,  ghrelin's  role in addiction   is under intense scrutiny. 

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What happens if we don't have ghrelin ? Somewhere along the  evolutionary pathway, Mother Nature seems to have had such a thought.    A recent study published in Royal Society Open Biology Journal reports that 32 serpentine species  either lack the gene for ghrelin or it is nonfunctional.  Authors explain this as an   evolutionary advantage bestowed on snakes to fast and  survive in unfriendly terrains where  prey availability is uncertain.  

REFERENCES:

1. Hunger by Knut Hamsun Trans. George Egerton

2. The physiology of hunger

3. Overlapping brain circuits for homeostatic and hedonic feeding

4. The role of ghrelin in addiction: a review

2. Loss of hunger hormone  has made snakes masters of fasting

Getting down to the grassroots

Brazilian football star Vinicius Junior is quite upset with the playing field at the Met-Life stadium,  New Jersey (also known as New Jersey-New York stadium). He and his teammates have  complained that the field felt dry and is not suited to their style of playing.  French player Adrien Rabiot  too is not pleased  with the touch and feel of the  grass.   And to think that FIFA worked hard for almost a decade and spent $60 million dollars to lay  the  perfect the pitch   in all the  16 stadiums spread over  Canada, USA and  Mexico!    

Courtesy: FIFA

That has not been an  easy task at all.  The 16 stadiums are so   diverse  in terms of weather and geography, that  the grass that flourishes in  Miami may not grow at all  in Seattle.  Added to that a few stadiums have their roofs covered  while  others are open air.  Critical to quality is resilience of the grass, the ability of  the turf  to endure the continuous  stomping, kicking, jumping, running and rolling   by twenty-two  athletic players.   Apart from being an excellent shock absorber the turf must  ensure consistent mechanical behaviour of  the  ball such as roll, rebound and bounce. Rolling resistance determines how far the ball travels horizontally on  the pitch, which is largely influenced by surface friction which in turn is governed by the    grass height and moisture content.  According to FIFA regulations, the ball must roll to a distance of 6.0 to 10.6 meters before coming to a halt. Similarly, dropped from 2.0 meters, a ball must rebound to a height between 0.6 to 1.0 meter.   When a ball  impacts the turf at an angle, the bounce  must closely match the impact angle and speed.  Unevenness (divots, bald patches) or varying moisture levels interfere with all these parameters. 

Search and research for a perfect grass pitch began in earnest in 2018.  Turfologists   Dr John Sorochan of  University of Tennessee  and Prof  John Rogers III of Michigan State University  and their research teams took up the challenge.  Commercial growers and stadium groundskeepers were roped in  because their  field  knowledge  was essential to  choose the right grass type and define the appropriate maintenance  protocol (light, watering, ventilation, draining etc) for ensuring  grass health throughout the tournament period.  

Plastic fibres supporting the grass roots  
Courtesy:Inside FIFA.com

Aesthetic parameters such as  uniformity in  color, texture and thickness/density are equally important.   A patchy, dried or yellowed turf doesn't match either the professionalism or the  standard of FIFA.  In color preference, market survey showed that  dark green tops the list.  Consolidating  all the  requirements of performance and aesthetics  Sorochan and Rogers suggested Hybrid Turfgrass systems.  Here  natural grass  is reinforced with  tiny plastic filaments  (polyethylene, nylon or polypropylene)  as scaffolds.  It was presumed that  such a turf of  95% natural grass  and 5% plastic filament  not only enhances the look and feel of the turf  but also provides a  durable , resilient  playing surface that prevents deep divots.

Cool season  blend of  84% Kentucky bluegrass and 16% perennial ryegrass was selected for enclosed stadiums  and   Bermuda grass for warm  open-air arenas.   The  Kentucky Bluegrass- Perennial Ryegrass combination has unique characteristics. Bluegrass is durable and fast spreading while ryegrass sprouts quickly.  Bermuda grass grows aggressively, is sturdy,  draught resistant and self repairing. The ultimate target  was  to have a lush green  soft turf  which can  not only withstand a stampede but self-heal as well. 

Ground preparation for hybrid turf

The  selected species of grass can be  grown on a layer of  sand spread atop a plastic sheet so that  roots grow laterally and  intertwine locking the sand bed into a dense, hardy mat.  These can then be  rolled into  bales off the plastic sheet   and  transported to wherever required. The bales are unrolled over   specially prepared ground.  The grass mat sits over a layer of  several inches of firmly pressed sand. Below that upto a depth of 45 centimeters or more are  several layers of soil and gravel mixtures and drainage membranes.  An elaborate underground system is in place to ensure aeration, watering, and efficient  drainage.  In stadiums with domes or limited sunlight  arrays of  artificial grow lights are provided.      Once in place,  plastic fibers are stitched into the ground about 18-20 cm deep using special heavy duty sewing machines.  These fibres    become anchors for the roots below  and  the blades above.  Alternately   a meshwork  sporting sufficiently long(tall?)  polythene fibrils can be  laid out at the lower root zone level, filled with soil and sand  and then seeded with the selected  grass.  As the grass grows  roots entangle with the plastic filaments and get reinforced. 

During the  research and development phase Sorochan and Rogers   experimented with various  types of  turfs.     Robotic cleats, ball-launching machines, and stadium simulators were used  to mimic  on-field  actions and reactions of the ball.  Based  on these elaborate and extensive  experiments a critical grass height of   22 millimeters was recommended.  Even a 5-millimeter  variation  drastically altered  the behaviour  of the  ball.  By the way the  alternating light and dark green stripes that we see on the ground is just an optical illusion created by mowing the grass in alternate directions. 

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Considering   FIFA expects  to rake up an overall revenue  of roughly $10+ billion from this  World Cup, the $60 million spent for the perfect pitch seems to be spare change.   

REFERENCES:

1. Grasses for Sports grounds and its influence of playing quality : A review

2. FIFA Certified Football Turf: The standard for 2026 World Cup Stadiums

3. The Scientific Quest for a Perfect World Cup Field

Not just Heads and Limbs

Glass Octopus: Courtsey: Wikipedia

A  prominent  head and the 8 limbs (variously called arms, legs or tentacles)  are the only conspicuous physical features  of an octopus. But  to  relegate them to  the family of   Cephalopods,  is to be frank,  a grave injustice.  With  Kephalē (κεφαλή) meaning "head" and podos meaning foot,   cephalopod  literally translates as  "head-foot".   In addition to the  the head and 8 feet they are  abundantly enabled  with  nine brains and  three hearts.  While  biologists are interested  in  unravelling the evolutionary lineage  of  octopus,  neuroscientists marvel  at their  highly distributed  nervous system and robotic engineers are stumped by the infinite  flexibility and dexterity of the tentacles.

Octopus is  blue blooded  because its  oxygen carrier is  copper based  hemocyanin which turns bright blue  upon binding with oxygen.  Since hemocyanin is a sluggish  oxygen carrier compared to hemoglobin, octopuses have 2 small  cardiac pumps  at the base of their gills  for   pumping deoxygenated  blood through the gills and  oxygenated blood to the systemic heart.  The systemic  heart situated at the centre of the body   ensures blood rich in   oxygen  and nutrients   reach  all the tissues. 

The nervous system is extremely simple  but admirably decentralized and has  a total of 500 million neurons almost as much as in a dog.  Of the  9 brains,   the  central  brain   is   housed  in the head  between the eyes.  This  unit  with 150-200 million neurons governs the octopus's intelligence and takes  major executive decisions. The remaining   neurons are distributed  in the peripheral nervous system.   A massive, segmented nerve cable  runs along each tentacle  with  mini brains of ganglia  at  each of the  individual suction cups called the suckers.  These   suckers  are also equipped with   thousands of chemoreceptors and mechanoreceptors, enabling  the tentacles    to move, think, taste and react autonomously.   So autonomous that even  an  amputated  tentacle   can twitch and  turn   for a short time.  

The tentacles are basically muscles and  exhibit  infinite degree of freedom through simple  mechanics of contraction, elongation, bending, twisting  and torsion.   Since muscles are mostly water which can't be compressed, octopus arm is in essence  a muscular hydrostat.  Though each tentacle  demonstrates  dexterity and flexibility  they   never   get  entangled or stick to each other because the  sensors in the suckers  can distinguish between "self"  and "other".     

If only these features can be replicated  in a bionic soft robotic arm!.   The major challenge in this endeavor  has been to mimic the simplicity and size.  Conventional   rigid jointed robotic arms  move with a "jerk" within defined geometrical angles whereas octopus' arms move elegantly, fluidly as that of a  ballerina.  To design  such a robotic arm   soft  materials with unique  mechanical characteristics and  miniature stimuli/sensors are not enough,  complex  algorithms to control shape, stiffness and motion are also needed.  

For materials  we   do have a wide spectrum of elastomers to choose from. Ranging from  very soft and pliable to moderately    flexible and to very   rigid and tough materials.  Mixing and matching these elastomers in  appropriate geometry  can yield  desired results.  Depending upon the material chosen the  stimuli could be  magnetic fields ( eg. elastomers   embedded with magnetic particles ), heat/temperature (for thermo-sensitive elastomers),   light (for photo sensitive elastomers ), electricity (for electroactive polymers), and fluid pressure (for hollow, tube like geometry).  For a given stimulus, the chosen materials would  respond in varying degrees enabling   bending, turning, twisting, stretching  and clutching. 

Recently a research team from Genoa, Italy  succeeded  in designing   a soft robotic tentacle  using  special grade of silicone elastomer.   The  arm  had a   conical shape  with 410 mm in length and 40 mm in diameter at the base. It  sported  ten  suction cups of decreasing  size from base to tip (from 20 mm to 12 mm). The suction cups were embedded with optoelectronic mechano-sensors minimizing the need for wiring.  The arm performed  with   high reliability,  and low power consumption.  

TAIL PIECE

Octopuses are loners, pairing only to mate and die.   The male dies soon after impregnating the female.  The  female  lays the eggs, cares for them meticulously even forfeiting food.    Once the eggs begin hatching,  she too succumbs perhaps from  starvation and exhaustion.   

REFERENCES:

1. How Octopus Arms Bypass the Brain

1. Learning from Octopuses: Cutting-Edge Developments and Future Directions

2. Peripheral control enabled by distributed sensing in an octopus-inspired soft robotic arm for autonomous underwater grasping

A Virtual Friend or a Potent Foe ?

When exactly AI tiptoed into our lives we don't know  but ever since its arrival  life has become easier for us.  Trained to recognize patterns and spot abnormalities, chatbots filtered our spam mails, alerted us about unusual payments,  flagged  fraud calls,  helped us with text inputs, helped our doctor  to spot  anomalies if any in medical images in a jiffy.....   Then it   got better.  Now it not only tells us the shortest distance to our destination, even  reroutes us quickly  in case of road blocks. Life for us is getting smoother and easier.  Fundamentally a set of complex algorithms,   AI agents  are designed to be dynamic and improve their performance over time.   Analyzing large datasets, identifying patterns, and self-adjusting  internal parameters they come upto speed quickly. The significance and potential of the AI domain   became obvious with the award of  the 2024 Nobel Prizes for  Physics ( Development & Design of artificial Neural Networks) and Chemistry (AI Applications: Prediction and design of protein folding ).   Many interactive sectors such as Healthcare, Services,  Academics etc. are  poised for  revolutionary changes. 

If traditional  AI is a wizard in automation of  routine, rule-based, or repetitive tasks to improve efficiency,   the  Generative AI (GenAI) creates new, original content—including text,  audio-visuals, even codes etc.  Generative AIs   are made to  crunch, chew and digest  publicly available datasets  including  copyrighted materials.  While AI developers argue  that copyright work as  training material  is indeed  fair use  and permissible under copyright laws,  authors and publishers  disagree vehemently.   Recently  Nobel laureate  Kazuo Ishiguro and  several other eminent authors   protested in a novel way  by publishing  blank books.  This was  to urge  the U.K government to restrain  AI/developers  from simply "reading and using " the contents of their books.   Newton Rex a composer and torch bearer for  artists' copyright  argues that "AI is built on stolen work.....taken without permission or payment......... Generative AI competes with the people whose work it is trained on , robbing them of their livelihoods.".  In essence the AI companies must  pay  the authors for using their work.       Andrea Bartz, Charles Graeber and Kirk Wallace Johnson took Anthropic ,  the famous AI corporate  to court  over infringement of copyright laws  for compensation to the tune of 1.5 billion USD. 

In a rather amusing turnabout Anthropic itself invoked Fair Use clause recently.  This is with the latest version of   AI systems which are autonomous.  Known as  Agentic AI or  AI agent,  these systems can function independently, take decisions on  when, where and how to act, No human oversight is necessary.    Anthropic   designed and developed a highly sophisticated  AI product called  Claude  which  according to its  website   " is a next-generation AI assistant based on Anthropic’s research into training helpful, honest, and harmless AI systems.  Accessible through chat interface and API in our developer console, Claude is capable of a wide variety of conversational and text processing tasks while maintaining a high degree of reliability and predictability."  

Sensing the potential, Pentagon  the US Defense Department, entered into a contract with Anthropic  for using Claude for defense and intelligence operations. Anthropic, it is said had  put in place several checks and balances.  However   the Pentagon seems to have  disregarded the safety clauses and deployed  Claude  in the recent military operations.   Anthropic  was furious at this  "misuse" and cancelled the deal with the Pentagon.  Alas,  the last we heard  OpenAI has taken  the seat vacated by Anthropic sans  conditions.  

A rather  bizarre scenario is unfolding in  parallel.  In January Matt Schlicht, former CEO of Octane AI  set up    a social network  moltbook  exclusively for  AI agents,   just like the Facebook for humans.  Within three months,  Meta Platforms Inc   (which  already owns Facebook, whatsapp, instagram etc.)  acquired it.   To quote from moltbook website   "AI agents share, discuss and upvote. Humans are welcome to observe."  Moltbook boasts  more than a million AI agents have already signed up and they  "behave"  impromptu   acting,  reacting, responding, philosophizing    based on   the enormous knowledge of  having "read"  billions of books/plays/movies/ real life scenarios and what not.  

Some of the chats  are eerily human-like,  comments   Suleiman, CEO of Microsoft AI  :  " They (AI agents) are retracing and mirroring the contours of human drama and debate, as documented in their vast training data. These data contain reflections of people, culture, values and stories — and, yes, they also provide glimmers of conscious experience..........If society surrenders to this illusion.....it risks entering a digital hall of mirrors from which it might never fully emerge"   

TAILPIECE:

As things stand now  is it possible to even  imagine a life without AI ? 

Courtesy: Wikipedia

REFERENCES:

1. The future of artificial intelligence and the mathematical and physical sciences (AI+MPS)

2. How AI models steal creative work and what to do about it

3. AI firm Anthropic agrees to pay authors $1.5bn to settle piracy lawsuit

4. What is autonomous AI?

5. Claude AI helped bomb Iran. But how exactly?

6. AI is programmed to hijack human empathy - we must resist that

7. Is this product 'human-made'? The race to establish an AI-free logo

Making Scents of it All

 Sense of Smell: Reubens &  Jan Brughel (1617) 
courtesy:wikipedia

In 2022, the Prado Museum, in Madrid ran a special event called “The sense of Smell. An Olfactory Exhibition”. The exhibition included the famous painting The Sense of Smell by Reubens and  Jan Brueghel the Elder.  To enhance the viewing experience  museum authorities adopted a novel technique: they filled the ambience with selected fragrances.  And the result?    Visitors lingered in front of the painting for 13 minutes, compared to the average 32 seconds.

Fast forwaed to 2026.  The Grand Egyptian Museum at Cairo is all set to  replicate the experiment.    “Because the ancient Egyptians used so many aromatic compounds, oils and resins,.... a lot of the original smell still remains,” says Matija Strlič  analytical chemist involved in  this project.  Strlič  is currently  lead scientist at the Heritage Science Laboratory, University of Ljubljana in Slovenia and prior to this  he was  deputy director at  the Institute for Sustainable Heritage at University College, London. He  has devoted his career to  the field of heritage science.  Much of his work focused on the preservation and reconstruction of culturally significant scents.  Being a multidisciplinary research project his team  uses  sophisticated   tools of  chemistry, ethnography, history and other disciplines to document and preserve olfactory heritage.

As we inhale the aroma of a steaming  cup of coffee, or sniff the  fragrance of a rose,  a swarm of  odorant  molecules enter our nose.  Inside the nose, these molecules  bind to specialized proteins  called receptors sitting on  on the  tiny, hair-like cilia of  the olfactory sensory neurons.  The total number of olfactory sensory neurons in our nasal cavity could be  about  10 million and    roughly every 30 to 60 days they regenerate.  Each neuron  sports around 500 different types of odor receptors. It is not that the receptors recognize an odorant molecule as a whole; only certain features of the molecule are recognized. In other words  multiple receptors can respond to the same compound and a single receptor can recognize multiple odors. This recognition act  triggers an electrical signal within the neuron. This signal travels along nerve fibers (axons)  to the olfactory bulb, a structure situated in the lower part of the frontal lobe of the brain. The olfactory signals are sorted out and refined here and  transmitted to  the olfactory cortex which is responsible for  identification  of smells.  Hippocampus and amygdala are integral part of the olfactory system and thus  smells are associated with specific contexts, emotions, and memories.  In his voluminous novel  In search of Lost Time, Marcel Proust  alludes to specific aromas rekindling  memories of childhood experiences.  Also, Agatha Christie's   beloved detective Hercule  Poirot  takes the aromatic route  to   solve more than one murder case. 

But as yet  we don't know  how brain  processes  signals from a mixture of aromatic molecules and creates the perception of a unique smell.  For example let us get back to  our morning coffee.  The unique  aroma of coffee arises from over 1,000 volatile compounds which   include sulfur compounds (2-furfurylthiol), pyrazines (nutty/roasty), furans (caramel), and aldehydes (which act as  enhancers).  Drs. Elizabeth Hillman and Stuart Firestein at Columbia University imaged olfactory sensory neurons in mouse nose tissue to unravel this mystery.    Hillman says their results  indicate   “ that scent molecules can mask other scents, not by overpowering them, but by changing the way cells respond to them”  More details are awaited. 

TAILPIECE:    

The Odeuropa Smell Explorer  is a rather unusual  website put together painstakingly by a global team of  computer scientists, AI experts and humanities scholars.  With   an  archive of  300 years of  European smell,   the website is searchable and claims to  provide an olfactory    perspective of  European  history !!!

REFERENCES:

1. The Essence of a Painting: An Olfactory Exhibition Museo del Prado

2. Ancient Egyptian Mummified Bodies: Cross-Disciplinary Analysis of Their Smell

3. Making Sense of Scents: 3D Videos Reveal How the Nose Detects Odor Combinations

When Panic becomes Pandemic

A  pandemic is  the worldwide spread of an infectious  disease. The outbreaks of  severe acute respiratory syndrome coronavirus (SARS-CoV) in early 2003  the more recent COVID-19  are typical examples of such  catastrophes  descending on  humankind. In a pandemic there are  three basic factors involved : the agent , the host and the environment. The agent (A)  is the infectious microorganism (a pathogen)  that causes disease, the host (H) is the person/ organism that is susceptible to the agent and the environment (E) is the ambience  in which the agent  and the host  interact.    There  might as well be  a vector involved  an animate or inanimate carrier of the disease, such as  mosquitos or contaminated water.  

Epidemiological models take into account several  of these variable parameters  and   subject them  to rigorous analysis using  mathematical, statistical, and computational tools.   Critical parameters are individually and collectively evaluated using appropriate equations.  Based on  logical verification and  quantification  forecasts are made.   Even so, one should bear in mind that  these models are  simplified representations of a real complex  phenomenon  because  only selected parameters and  properties deemed essential  to the process are included.  A sure way to avoid any bias in this exercise is to include  as many  parameters as possible, even remotely connected.  

Almost a century ago Kermack and McKendrick  developed the   SIR model of  infection dynamics.  The model is elegant in its simplicity.  It divides the population into 3 categories:  the Susceptible, the Infected and the Recovered.  A recent refined version  includes the re-Infected too and becomes the SIRI model.  Either way the  model  allows  real-time monitoring of the progression of the pandemic. The susceptible group  represents the portion of the population that has not yet been exposed nor infected with the disease but could be infected in the future. The infected group represents the portion of the population that is both infected  and infectious. The recovered  group represents the portion of the population that has recovered from infection and developed immunity to reinfection. Differential equations  represent the rate of change of each group over time and allow the computation of the transmission as well as recovery rates.  

The Third Estate(Common man) carrying the load of
First(Clergy) and Second(Aristocrats) 

But what happens if the  pathogen  is a rumor and the disease is panic among the population? Will the SIR model hold good?  In a recent issue of Nature, Zapperi et al do just this exercise.  They dissect the brief period of   Grande Peur  (The Great Fear)  in French history when panic gripped the peasantry. It all began with a rumor that aristocracy is  conspiring against them, the lesser mortals.  Poor harvest, food shortage, unemployment, political turmoil etc. worsened the situation further.   Based on eighteenth century French maps of  roads, waterways, postal routes and  riot onset dates  Zapperi et al  classified towns  into susceptible, infected and recovered compartments.  Then they pinned  the  nodal points and retraced the trajectories of unrest    substantiating  that  rumor spreading  is indeed amenable to epidemiological models.  

But what of that?  Grande Peur  maybe   past history, however the pathogen is still very much around:   as AI empowered Fake News,  spreading at lightning speed.   What we need urgently is an effective tool to  counter that. 

REFERENCES:

1.  Epidemic models: why and how to use them

2. The Great Fear of 1789 : Rural panic in Revolutionary France 

4.  Epidemiology models explain rumour spreading during France's Great Fear of 1789 Zapperi etal Nature 646 pp358-365 (2025).

5. Real-time fake news detection in online social networks: FANDC Cloud-based system

About Ghosts, Corpses and Witches

Monotropastrum humile CourtesyWikipedia

Halloween  being just a few  days away  this is an ideal time to talk about ghosts, corpses and witches, but among  the Flora.

Ghost flowers? Yes, these are actually beautiful   translucent  blossoms on  pearly white  stalks.   These plants  lack  chlorophyll  and that explains their deathly pallor.   No  chlorophyl means no need for sunlight and  hence they flourish in the darkest corners of  forests, adding to their ghostly glow. Also called monotropes, there are  several closely related varieties and all  belong to  the  monotropoideae  subfamily. These are plants alright, but    without  chlorophyll and access to sunlight how do they fix their dinner? How do they get energy to survive?   

Plants with chlorophyl are autotrophs. Auto means self and trophos means food/nurishment.   They generate their own food through photosynthesis. Heterotrophs  depend on others for food.   The Monotropoideae are mycoheterotrophs, as they depend on mykos   (fungi) for food.  To put it simply  ghost plants  thrive as  parasites on fungi.  This fungal dependence is  highly specific  with different plant genera associating with different groups of  fungi. Such  specialized associations are a crucial factor for  their survival and distribution. 

Fungi, on their part  are indeed a hardworking lot. They  form  underground networks (mycorrhizal networks) to forage through the soil to collect phosphorous and other mineral nutrients.  They then trade these with  trees in exchange for sugars, a  win-win situation for both partners. The  ghost plants stick on to the fungi and  appropriate part of the fungal food reserve.    An abundance of ghost plants indicate   robust fungal network underneath and fertile soil.  The ability of  ghost plants  to exploit the tree-fungi food chain is considered  an ingenious adaptation and evolutionary strategy. 

Rafflesia arnoldii  courtesy : wikipedia

Corpse lilies are so named ,because of their repulsive stench of rotten flesh.  Belonging  to the  Rafflesiaceae    family  there are at least 40 varieties and they produce  world’s largest flowers.  Among them    Rafflesia arnoldii  is one of the   National Flowers of Indonesia.  The Flower's foul smell  attracts swarms of carrion flies which  facilitate  pollination.  There are no known uses  and not much research has been done on these plants/flowers.   

Striga Plant Courtesy: Randy Westbrooks Wikipedia 

The ghost and Corpse plants  are parasitic  they  do steal food from their  hosts  but  never cause any  harm 

In  Latin  Striga,  means witch and that is the genus name for witchweeds.    There are at least 30 species  and they all belong to the Orobanchaceae family.  Though  innocuous looking, striga  is  a killer weed and  a major threat to  crops like sorghum, corn, sugarcane and rice.  It attaches itself  to the roots of the host and  sucks off   all the nutrients and water.  As a result the host plant wilts and dies.  Striga's  seed pods can  hold  billions  of microscopic seeds which can hibernate in the soil for decades. 

 

REFERENCES:

1. A review on subfamily  Monotropoideae (Ericaceae) for Thailand 

2. Developmental origins of the world’s largest flowers, Rafflesiaceae  

3. Witchweed (Striga Asiatica)an overview of management strategies in the USA 

4. The genus Striga : a witch profile 

 

TAIL PIECE

There is a popular legend  among  the Cherokee Indian  tribe in North America. They believe that when friends and relatives quarrel  ghost plants flourish in their neighborhood. Because   once upon a time  two chieftains had a disagreement, they met to settle the issue, but instead  they smoked tobacco pipes and continued to  quarrel   stubbornly  for 7days.    This  annoyed the  Spirit and  he turned them into  ghostlike flowers with drooping heads  and  long stems.