Archive for March, 2013

Not all clicks are created equally…

The other week I did a guest blog post over at Scientific American. It was essentially about my thoughts on how to write to your own particular brand of sensibilities — your niche. The day of being a generalist science writer has probably already come and gone. And besides, the way science communication has evolved, we shall see more and more experts take to the proverbial airwaves — not only as advocates for their science but as genuine great science communicators.

“The internet has been the great democratiser of just about everything we can think of. But perhaps news, journalism, and writing were the ones to fall furthest and from the greatest height when the playing field was levelled. In this information age, we are now forced to become digital natives. Everything has to be framed for the Internet—search engine optimization, 140 characters, and all. While in the “good old days” of print, journalists and writers competed for the frontpage, now they compete for clicks. The more eyeballs, the better. In order to adequately communicate science online, one must acknowledge this situation before attempting to do something about it.”

And thanks to Khalil over at SciAm’s Incubator Blog.

The Contagion of Violence…


When Professor Plum killed Dr Black, in the library, with the candlestick it was for no other reason than murder is a disease. Murder is infectious and the contagion of violence is everywhere.

Violence begets violence.Violence within nations and cultures. It occurs within families and between partners. It increases the risk of violence directed at children and increases the risk of the children behaving violently themselves. Violence within a community perpetuates and spreads. Children catch it from their parents, and parents can catch it from their children. Violence is highly contagious in all respects it seems.

It was a 2012 essay by L. Rowell Huesmann that sparked off a study, appearing in Justice Quarterly. A study with a simple premise and question; if homicide is infectious, it should diffuse through communities, infecting those susceptible, and that diffusion should be detectable. Much in the same way we can track the flu from year to year, we can track the spread of murder as an epidemic. It offers an interesting way of looking at murder and homicide.

Welcome to Newark, New Jersey. A city that houses roughly 277,000 people has a homicide and murder rate over three times greater than that of anywhere else in the US. There were 104 murders and 504 shooting victims in 2006 alone. Firearms were used in 71% of the 380 reported murders in 2011. Suffice it to say, Newark is not a safe place.

The study took a look at how murders and homicides moved and behaved over a 26-year period (1982 to 2008) across the city. Firearms and gangs were the infectious agents; spreading from within the centre of the city and spreading south-westerly over the course of nearly three decades.

Their main argument is that the way murders move across a community is not random. The elements required for disease to propagate itself may be relevant and can be applied to the movement of homicide. And if this is so, then it can be predicted and controlled.

If you take a look at a map of Newark it is hard to see a pattern. Homicides occurred in all parts of the city. Almost the entire city appears to be a hot spot for murder. But analysis over the decades suggest that there was expansion of overall homicides between 1982 and 2008 with a dip in 1997 and a sharp rise in 2000. And highlighted an area of the city (North and East) that seemed largely immune to the spread of homicide. Indeed, murder was on the move.

The criminal justice system seeks to prevent murder, but only after the fact — by deterring those that do it with the penalty that awaits them after the fact (jail and criminal prosecution). Indeed, police forces already have an eye out for certain hotspots within a location. Areas where violence is known to spark and ignite at any given moment. What they don’t know is where it will go next. The authors of the study model homicide as an infectious disease as simply a way to offer instructive understanding of how homicide works. The most telling application of this non-literal model is the fact that for homicide to spread as a disease, a population susceptible to transmission must be present. Just like every other infectious agent, except this time poverty and social inequality replace a population with no herd immunity.

Image — source

Zeoli, A., Pizarro, J., Grady, S., & Melde, C. (2012). Homicide as Infectious Disease: Using Public Health Methods to Investigate the Diffusion of Homicide Justice Quarterly, 1-24 DOI: 10.1080/07418825.2012.732100

Invasion of Asian tiger mosquitoes…


Sometime during that glorious decade known as the 1980s, a shipment landed in Houston, Texas. A shipment carrying more than its cargo. The point of origin was Japan. The shipment was used tires. The payload was Asian tiger mosquitoes.

Within years of landing in Texas the tiger mosquito, Aedes albopictus, rapidly displaced resident populations of Aedes aegypti mosquito. Both are important disease vectors. The native being considered the primary vector of breakbone fever — or dengue. And the Asian tiger mosquito recently emerging as the most important transmitter of chikungunya virus and yellow fever. By September 1986, the range of the Asian tiger mosquito had extended as far north as Utah. The demise of the native Aedes aegypti had already begun — representing not a transient ecological phenomenon, but the beginning of permanent colonisation, and resulting in rapid declines and extinctions of the native mosquito species.

Aedes aegypti originated in Africa and was introduced to the Americas between the 15th and 18th centuries, during the height of the slave trade and most likely on ships transporting slaves. They quickly established across the south eastern part of the US. Then what followed was a demise in the face of stiff competition and after centuries of habitation in America. An inadvertent metaphor for the “Post-America” era we now inhabit.

Across the Americas, Europe and Africa, Peru, Brazil, Mauritius, New Zealand, Guam and even the island of Fiji, invasive mosquito species have been documented to colonise. The tiger mosquito that landed in Texas invaded most areas of the southeast United States within 3 years, a spectacularly rapid event forcing of A. aegypti out of its niche. A similar phenomenon was observed in Bermuda, where the colonisation and invasion was just as fast.

Two species cannot simultaneously occupy the same niche, and for years since researchers noticed the Asian tiger mosquito had overtaken the native species, hypotheses as to how this occurred have been bandied around. From larval resource competition, to greater reproductive efficiency of the tiger mosquito, to desiccation-resistant eggs of the tiger mosquito (which enhance survival in inhospitable environments).

Two species of mosquito within the same niche throws up an interesting predicament in terms of mating and competition for the female population. In Texas, the tiger mosquito can mate with the native species. The male tiger mosquito thought to be more aggressive in trying to mate with female resident species — like a sailor on shore leave — in comparison to the native males. But for some reason researchers couldn’t show this, even in laboratory cages.

The parasites within the tiger mosquito was posed as another hypothesis to explain colonisation. Both the tiger and native mosquitoes share a common parasite. Aedes mosquitoes typically harbour parasites of the genusAscogregarina, and the species that parasitizes the tiger mosquito can also infect Aedes aegypti, leading to some impressive death rates.

All hypotheses proposed were inadequate on their own for explaining the patterns observed in nature, and none served as a good explanation to describe the colonisation of the tiger mosquito. Recently, a group of researchers from the Florida Medical Entomology Laboratory have added an interesting facet to the “competitive displacement” phenomenon.

A form of reproductive interference — satyrization. The term describes how males of one species mate with females of a related species, producing no viable offspring. A mechanism that has already been shown to lead to population extinctions in other species.

It all has to do with the mating balance in this unique mosquito species pair. The fact that both species share a common mating behaviour only makes it more likely that errant and erroneous mating will occur. The mistake of mating with an Asian tiger male is extremely costly for the native females, and can end up in sterilization and the loss of future reproductive potential. What researchers found was that where the species have coexisted for some time and interspecies mating occurs, the native females avoid mating with unsuitable Asian tiger males. And, it seems, this doesn’t occur at the outset — when two species are immediately introduced to one another.

They describe it as selection at work — or rather a way to protect their reproductive potential. This development of resistance to satyrization may allow recovery of native populations in the face of invading species. But this simple fact is a double edged sword, as a resurgent native population carry the risk of resurgent dengue fever.

[Image courtesy of Jim Newman]

Bargielowski IE, Lounibos LP, & Carrasquilla MC (2013). Evolution of resistance to satyrization through reproductive character displacement in populations of invasive dengue vectors. Proceedings of the National Academy of Sciences of the United States of America, 110 (8), 2888-92 PMID: 23359710

Super-villain watch… Part IV


Super-villain watch is an attempt to catalogue all the suspect science and technology research going on out there that could easily wind up in the pages of a comic book or a B-movie film. The story is always the same. With some hyperbole — poor scientist out to do good creates technology, world does not appreciate scientist’s genius, scientist turns technology on world to take his revenge. A discussion for another time is why do all the supervillains out there seem to have advanced degrees? I have a suspicion it is the PhD process, but we’ll get to a deeper analysis some other time.

Part IV’s super-villain watch takes very little of a mental leap to imagine a turn to the dark side.

From NewScientist

“The suit, called SpiderSense and built by Victor Mateevitsi of the University of Illinois in Chicago has small robotic arms packaged in modules with microphones that send out and pick up ultrasonic reflections from objects. When the ultrasound detects someone moving closer to the microphone, the arms respond by exerting a growing pressure on the body. Seven of these modules are distributed across the suit to give the wearer as near to 360 degree ultrasound coverage as possible.”

This is exactly how super villains are created.

“Mateevitsi tested the suit out on students, getting them to stand outside on campus, blindfolded, and “feel” for approaching attackers. Each wearer had ninja cardboard throwing stars to use whenever they sensed someone approaching them. “Ninety five per cent of the time they were able to sense someone approaching and throw the star at them,” says Mateevitsi.”

Previous super villainary: Part I, Part II, Part III

What had I twaught…

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