Topology is the mathematical study of distorting objects through stretching them (this also includes some aspects of networks as distorting the links between nodes does not change the inherent pattern of the network). A system that can be studied under topology and that exists in nature would be flexible circular chains. Their ability to stretch and contort matches many of the prerequisites of topology. The example important for today is plasmids.
The easiest response to the question “why do we need to sleep?” is simply that “we get tired.” In truth this is the best explanation we have. Obviously people perform better in a variety of mental and physical tasks when they are not tired and sleep has definite benefits relating to the physiological effects it has on us (lower body temperature, faster healing of wounds, ect). It has been shown that rats forced to not sleep eventually died; but exactly what killed them? Whether it was the breakdown of cells or an infection or perhaps their rapid drop in body temperature is still unknown, meaning that we don’t know what exactly about sleep keeps us alive.
It is common to hear people talk about the five senses of sight, smell, touch, hearing and taste. Of course there are plenty more senses and one of the more important is the sense of gravity and acceleration (closely related to the very literal sense of balance). This is produced by the vestibular system in the ear. The main component of this system is the otolith, a small bone which moves and brushes tiny hairs which tracks the acceleration. The human system has advanced beyond this with more complex features integrated into the bony labyrinth but for the larval stage zebra fish used in this study the otolith is the only relevant feature.
I have previously written about birds and their uncanny ability to know what direction north is here. Both that and this post are both on the topic of birds’ ability to see magnetic fields probably caused by a magnetically sensitive cell in the eye. But the exact nature of this magnetoreception is still unknown. The two main theories are that either a iron containing particle could interact with the magnetic field to aid navigation or perhaps that light induced radical pairs of electrons could have their spins slightly biased based on a ever present magnetic field. This second idea is the one that is examined more closely as if the theory is true the mechanism would be quantum mechanical in many ways.
Diseases such as emphysema, bronchitis and severe asthma can be described together as Chronic Obstructive Pulmonary Disease (COPD). As people grow older they are much more likely to suffer from one of these diseases and much more likely to assume the symptoms are just a sign of getting older. It is said that 30 million people in the USA currently have it and it is predicted that COPD will be the third highest cause of death by 2020. It is believed that air pollution can be a aggravating feature of the disease and considering that 3 billion people world wide are exposed to biomass smoke, the smoke produced by burning any living thing, as compared to the 1 billion tobacco smokers in the world, it is very possible biosmoke actually leads to more cases of COPD.
Last year a paper was published on a study of bees. Insect brains contain a pair of structures called the mushroom bodies. These sections are believed to mostly focus on the sense of smell and in particular memory related to smell. The study examines the possibility that imidacloprid, an insecticide that acts as a neurotoxin, could affect bees such that even when a non lethal dose was received, the bees would be permanently impaired afterwards. The conclusion was that the density of synaptic units in the mushroom bodies and related calyces was indeed decreased when the developing larvae were fed small amounts of imidacloprid. This could easily lead to the grown bees lacking cognitive functions related to smell and suffering an extremely hampered foraging ability. But interestingly another study has come out just yesterday attempting to refute (or at least question) these claims.
Axotomy is the process of severing of an axon which is normally done with a laser in today’s modern society.
Once a mammal has become an adult their ability to heal neurones and repair the nervous system becomes practically non existent. Of course there are some species of animal of different class which can repair nerve damage although these are normally simple creatures. One such example is the roundworm caenorhabditis elegans (called a nemotode in the US) which can regenerate broken neurones and is commonly studied as it is also transparent so optical observation of healing can be done. Other advantages of using this worm in studies is that they can be grown quickly and cheaply as well as being vulnerable to the laser controlled axotomy mentioned above.