Population dynamics

Stochastic modeling of a serial killer


M.V. Simkin and V.P. Roychowdhury: We analyze the time pattern of the activity of a serial killer, who during twelve years had murdered 53 people. The plot of the cumulative number of murders as a function of time is of  "Devil’s staircase" type. The distribution of the intervals between murders (step length) follows a power law with the exponent of 1.4.

Pitt Team Designs Artificial Cells That Communicate and Cooperate Like Biological Cells


Researchers develop first models for producing polymer-based artificial cells capable of self-organizing, performing tasks, and transporting “cargo,” from chemicals to medicine, according to report in Proceedings of the National Academy of Sciences.

Forget the weather forecast - it's women's hemlines that determine a heatwave


If you want to know what the weather is up to, it might be best to start looking down. For apparently the length of a woman’s skirt is a good way of forecasting whether to expect rain or shine.

Was a giant comet responsible for a North American catastrophe in 11000 BC?


13,000 years ago the Earth was struck by thousands of Tunguska-sized cometary fragments over the course of an hour, leading to a dramatic cooling of the planet, according to astronomer Professor Bill Napier of the Cardiff University Astrobiology Centre. He presents his new model in the journal Monthly Notices of the Royal Astronomical Society.

Selective hearing is all in the mind, finds new study that could help partially deaf


 Scientists said the 'cocktail party' problem, where someone struggles to 'zoom in' on what a friend is saying in noisy surroundings is more down to that person's brain and not their ear.

Researchers Discover New Lineage of Ancient Human


DNA from a 40,000-year-old human finger bone found in a Siberian cave points to a new lineage of ancient human, researchers report today. The find—the first made with genetic, not fossil evidence— suggests that Central Asia was occupied at that time not only by Neandertals and Homo sapiens but also by a third, previously unknown hominin lineage. "This is the most exciting discovery to come from the ancient DNA field so far," says Chris Tyler-Smith, a geneticist at the Wellcome Trust Sanger Institute in Hinxton, United Kingdom.

Dinosaurs Rode Volcanic Armageddon to Victory


Geologists have turned a series of 200 million-year-old lake-bed sediments into an epic narrative of the dinosaurs’ journey from ecological obscurity to Earthly supremacy, a mystery that has lingered even as their disappearance is explained.

The dino path to dominance appears to have been cleared when the supercontinent Pangea cracked, setting off 600,000 years of volcanic activity that wiped out the dinosaurs’ crocodilian competitors.

Best Connected Individuals Are Not the Most Influential Spreaders in Social Networks


Who are the best spreaders of information in a social network? The answer may surprise you. The study of social networks has thrown up more than a few surprises over the years. It's easy to imagine that because the links that form between various individuals in a society are not governed by any overarching rules, they must have a random structure. So the discovery in the 1980s that social networks are very different came as something of a surprise. In a social network, most nodes are not linked to each other but can easily be reached by a small number of steps. This is the so-called small worlds network.

Stochastic modeling of Congress


We analyze the dynamics of growth of the number of congressmen supporting the resolution HR1207 to audit the Federal Reserve. The plot of the total number of co-sponsors as a function of time is of "Devil's staircase" type. The distribution of the numbers of new co-sponsors joining during a particular day (step height) follows a power law.

Human Ancestors Were an Endangered Species


With 6.8 billion people alive today, it's hard to fathom that humans were ever imperiled. But 1.2 million years ago, only 18,500 early humans were breeding on the planet--evidence that there was a real risk of extinction for our early ancestors, according to a new study.

Syndicate content