It must be love, love, love

In the brain, romantic love shows similarities to going mildly insane or suffering from obsessive compulsive disorder. Studies show that when you first fall in love, serotonin levels plummet and the brain's reward centres are flooded with dopamine. This gives a high similar to an addictive drug, creating powerful links in our minds between pleasure and the object of our affection, and meaning we crave the hit of our beloved again and again.

The four stages of love

• Lust -  driven by the sex hormones testosterone and oestrogen.
• Attraction - In the attraction stage, a group of neuro-transmitters called 'monoamines' play an important role:
• Dopamine - the same chemical activated by cocaine and nicotine
• Norepinephrine (adrenaline) - Starts us sweating and gets the heart racing.
• Serotonin
• Attachment - 
• Oxytocin - released by the hypothalamus gland during child birth and also helps the breast express milk. It helps cement the strong bond between mother and child. It is also released by both sexes during intimate activities.
• Vasopressin

Happy valentines

Why do we enjoy music?

The sounds of music are not the same as other noises we hear on a daily basis. Your ears are one way to ensure your survival: they're a warning system, designed to analyse sounds for danger. But we can quickly recognise that a musical instrument as harmless. When you hear music, your ear drum moves in and out in a regular, repeated way, many times a second. We recognise that it's not dangerous, so we can focus on the harmonies and tunes – and enjoy them.

There are many sorts of music, and we enjoy them in lots of different ways. In films, music echoes the action. Several clichés have been built up – like strings and piano for romantic moments – but we enjoy them. In some cases, the music builds tension and we enjoy guessing what's going to happen next. If you look at "serious" music, like classical or jazz, anticipation and release are a major part of our enjoyment. The composer or improviser will set up expectations and then either reward or frustrate them. It's like telling a joke, where the punch line either fits the story, or is a surprise: in both cases, we get pleasure.

Drumming was probably the first sort of music; hitting things with a stick is fairly easy. Rhythm is good for dancing or entering hypnotic states, so that's an ancient response that we have to music. Our enjoyment of dance music is simple to understand: you can't really dance without it, and we enjoy dancing. Pop music involves short, ear-catching, easy- to-remember melodies. It's like eating sweets: instant gratification.

Musical systems are learned at an early age. Babies will sing several hundred different notes over a few minutes. But that song can't be repeated, so it's not much fun. The baby then listens to its parents singing nursery songs which only have a few notes, so the baby can learn to remember them and enjoy them.

Western music uses a lot of harmonies, where all the notes used at any one time agree with each other to some extent. Other musical systems are slightly different. There is no scientific reason at all why you'll prefer one type of musical to another. Everybody could enjoy more kinds of music if they gave them a chance – but sadly we tend not to do so. With food, if you try something properly 10 times you'll probably come to like it. It's the same with music, but people often close up their range of musical appreciation by the time they're about 25. But it's easy to increase your enjoyment of life by listening to a lot of different types of music.

Why do we sleep?

On average, we spend a third of our life sleeping. That's around 26 years if we live till 80. For something that we do for a large bulk of our life, we know very little about it. Some believe that sleep gives the body a chance to "recuperate" from the day's activity, however, the amount of energy saved by sleeping is only 50kCal per 8 hours... that's less than a packet of crisps. Sleep occurs in recurring cycles of 90 to 110 minutes and is divided into two categories: non-REM and REM sleep.

Non-REM Sleep

• Light sleep - half awake and half asleep. Muscle activity slows down and slight twitching may occur.
• True sleep - after around ten minutes of light sleep, we enter true sleep lasting around 20 minutes. Ventilation rate and heart rate begins to slow down.
• Deep sleep - brain begins to produce delta waves (high amplitude, low frequency), ventilation and heart rate at their lowest. If awakened during deep sleep, we do not adjust immediately and often feel groggy and disorientated.

REM Sleep

• Rapid eye movement (REM) period begins around 70 to 90 minutes after falling asleep. 
• We experience around three to five REM episodes every night. Although we are not conscious, our brain is active, allowing dreams to occur. Breathing rate and blood pressure rises.

One of the most recent and compelling explanations for why we sleep is based on findings that sleep is correlated to changes in the structure and organization of the brain. This phenomenon, known as brain plasticity, is not entirely understood, but its connection to sleep has several critical implications. It is becoming clear, for example, that sleep plays a critical role in brain development in infants and young children. A link between sleep and brain plasticity is becoming clear in adults as well. This is seen in the effect that sleep and sleep deprivation have on people's ability to learn and perform a variety of tasks.

Epidemiology

Epidemiology is the study of the distribution and determinants of health-related states or events, and the application of this study to the control of diseases and other health problems. 


John Snow was a British physician and is considered to be the father of modern epidemiology. He is famous for his investigations into the causes of the 19th century cholera epidemic in Soho. He noticed that significantly higher deaths were recorded in households that frequently used the Broad Street pump for water. He used a spot map to illustrate how the cases of cholera were clustered around the pump. Snow then attempted to clean the water using chlorine, and removed the handle on the pump, so no-one could use it. Later, it was discovered that the well had been dug only three feet from an old cesspit (a pit covered in cistern, used to dispose of urine and feces), which was leaking fecal bacteria.

A quick break from medicine... The infinite monkey theorem

"A monkey hitting keys at random on a typewriter for an infinite amount of time will almost surely type a given text, such as the complete works of William Shakespeare".

First we need to get a few things straight:

• It doesn't have to be a monkey - it is just a metaphor for an abstract device that produces random sequence of letters and symbols.
• 'Almost surely' has a specific mathematical meaning.
• It doesn't matter if there's an infinite number of monkeys with typewriters, one monkey for an infinite amount of time, or an infinite number of monkeys for an infinite amount of time.

Almost surely?

The difference between an event being 'almost sure' and 'sure' is the same as the subtle difference between something happening with probability 1 and happening always. If an event is sure, then it will always happen. No other event can possibly occur even if the other event’s probability is 1. If an event is almost sure, then other events are theoretically possible in a given sample space (a sample space is a set of the possible outcomes), however as the size of the sample space increases, the probability of any other event nears zero.

The point is, that given an infinite amount of time, every single combination of letters, words, symbols and numbers ever, will be written. One monkey may type out the complete works of Shakespeare but misspell Romeo as Rameo, one monkey may be one full stop away from completion, and stop typing.

Anderson's model

Programmer Jesse Anderson wanted to give Amazon’s Web Services — cloud-based storage, data processing, virtual private servers, etc. — a try so he decided to test out the Infinite Monkey Theorem. The monkeys were replaced with software that outputs random letters and their writing is being combined to recreate the complete works of Shakespeare. 3,696,348 characters in total.

Using Anderson’s method each individual has to type just nine characters that match the source text before the program adds that string to the collected pool of Shakespeare text. This should make the project go much more quickly than if a single monkey had to accidentally recreate a work that is tens of thousands of characters long, which is how the theory generally goes.

This is an image of how much of the complete works of Shakespeare the virtual monkeys have covered so far (green).

Telomeres

Our genes are located on twisted double stranded molecules of DNA called chromosomes. On the ends of the chromosomes, there are stretches of DNA called telomeres. Telomeres protect our genetic data, makes it possible for cells to divide and many believe holds the secrets to ageing and cancer.

Without telomeres, the main part of the chromosome containing genes essential for life would get shorter after each cell division. So telomeres allow cells to divide without losing genes. Cell division is essential for growth of new skin, blood, bone and other cells. Also without telomeres, chromosome ends could fuse together and degrade the cell's genetic blueprint, making the cell malfunction, become cancerous or die. Because broken DNA is dangerous, a cell has the ability to sense and repair chromosome damage. Finally, without telomeres, the ends of chromosomes would look like broken DNA, and the cell would try to fix something that wasn't broken. That also would make them stop dividing and eventually die. 


Before a cell can divide, the chromosomes within it are duplicated so that each of the two new cells contains identical genetic material. A chromosome's two strands of DNA must unwind and separate. An enzyme (DNA polymerase) then starts to make two new strands of DNA to match each of the two unwound strands. It does this with the help of short pieces of RNA. When each new matching strand is completed, it is a bit shorter than the original strand because of the room needed at the end by this small piece of RNA. It is like someone who paints himself into a corner and cannot paint the corner.

A printed jaw transplant for a woman with osteomyelitis

In June 2011, an 83-year old Belgian woman was given the first ever replacement surgery for an entire lower jaw. The replacement jaw, created by a 3D printer, has proven to be as functional as her own used to be.

Osteomyelitis
The woman had lost her entire lower jaw due to this bone infection known as osteomyelitis, caused by bacteria or fungi. There are two main types of osteomyelitis: acute, where the bone infection develops within two weeks of an initial infection, injury or underlying disease, and chronic, where the bone infection has produced irreversible changes in the bone structure. Acute osteomyelitis can usually be treated by antibiotics.

• Contiguous osteomyelitis (acute) is caused by infections spreading directly into the bone as a result of an injury, such as a fractured bone.
• Haematogenous osteomyelitis (acute) is where infection spreads into the bone through the bloodstream.

Chronic osteomyelitis can start as acute osteomyelitis if not treated properly, causing the bacteria/fungi to produce permanent, destructive changes to the bone. It may also develop as a complication of pre-existing infections such as TB or syphilis.

How was the replacement jaw made?

Researchers at 'Biomed', the biomedical research department of the University of Hasselt, Belgium, worked with a 3D printing firm called Layerwise, who specialise in ultrastrong titanium. An MRI scan was taken of the patient's ailing jawbone to get the correct shape, which was then fed into a laser sintering 3D printer which fused tiny titanium particles layer by layer until the shape of her jawbone was recreated. The replacement jaw was then coated with biocompatible ceramic layer, and had dimples and cavities to promote muscle attachment, and sleeves to allow mandibular nerves to pass through.

The four hour surgery was successful, and allowed the woman to speak, chew and breathe normally again.