Jamie Morton is the NZ Herald's science reporter.

Weird Science: NZ sea lion a cold-blooded killer?

Researchers have found the endangered NZ sea lion is among the most murderous of mammals. Photo /  File
Researchers have found the endangered NZ sea lion is among the most murderous of mammals. Photo / File

Researchers have mapped out the homicidal histories of more than 1000 mammals - and found that the New Zealand sea lion was among the most conspicuous.

In a long list compiled by an international team of scientists, who just reported their findings in the major journal Nature, the critically-endangered seal species stood out alongside the lion, long-tailed marmot, banded mongoose and red-fronted lemur as having the highest rates of so-called "conspecific deaths".

But, of course, the bigger story was us humans, who, unlike bats and whales, don't exactly have a clean record.

The study authors found that "lethal interpersonal violence" was a particular feature of primates and was likely to have been inherited by humans during the course of evolution.

Taking data from a variety of human and mammalian sources, ranging from 50,000 years ago to the present, they predicted that the overall proportion of human deaths caused by interpersonal violence stands at around two per cent - a figure that matched the observed value for prehistoric man.

When climate change makes you sexier

This common marine crustacean has shown researchers that it's all set to beat climate change. Photo / Katherine Heldt
This common marine crustacean has shown researchers that it's all set to beat climate change. Photo / Katherine Heldt

They're few and far between, but some odd positives do spring up from the otherwise catastrophic picture of global climate change.

A common marine crustacean has shown researchers that it's all set to beat climate change - the males will get more attractive to the females, with a resulting population explosion.

The Australian study is the first to show how mating behaviour could change under the warmer waters and more acidic oceans brought by climate change.

University of Adelaide researchers studied the herbivorous amphipod in large tanks under the elevated temperature and CO2 predicted for 100 years from now, and found the population increased twenty-fold under the predicted warmer waters.

"It got even more interesting, however, when we dug deeper and found that males were much larger in size than in previous generations under cooler waters and lower CO2, and their bigger claws were disproportionately larger still," study co-author Dr Pablo Munguia said.

"On top of that, where there had been variation in large claw size throughout the population, suddenly all the males had large claws."

This happened only within a few generations.

"It seems that sexual selection for this attractiveness trait could mean that every male was equally attractive to the females, resulting in very large numbers of females - almost 80 per cent - becoming pregnant, causing a massive population explosion."

A strange way to treat garlic breath

Raw apple or lettuce could be just the trick to cure your garlic breath, say scientists. Photo / File
Raw apple or lettuce could be just the trick to cure your garlic breath, say scientists. Photo / File

If you're a garlic lover, keep an apple handy - or maybe a nice chunk of lettuce.

US researchers have pointed to the two options as post-garlic halitosis-busters, publishing their weird findings this week in the Journal of Food Science.

In their study, they gave participants three grammes of softneck garlic cloves to chew for 25 seconds, and then either water, apples, lettuce, mint leaves or green tea were consumed immediately.

Raw apple and raw lettuce were found to decrease the concentration of volatiles in breath by 50 per cent or more compared to the control for the first 30 minutes.

According to the researchers, foods deodorise garlic breath through two mechanisms.

First, enzymes in the raw foods help to destroy the odours, and then, phenolic compounds in both the raw and cooked foods destroy the volatiles.

That's why raw foods were generally more effective because they contain both the enzymes and the phenolic compounds.

An even stranger way to help pass kidney stones

A quick ride on a roller coaster might help you pass that bothersome kidney stone, a US urologist reports.
A quick ride on a roller coaster might help you pass that bothersome kidney stone, a US urologist reports.

A US urologist has discovered that riding a roller coaster helps patients pass kidney stones - with nearly a 70 per cent success rate.

"Basically, I had patients telling me that after riding a particular roller coaster at Walt Disney World, they were able to pass their kidney stone," said Emeritus Professor David Wartinger, of Michigan State University.

"I even had one patient say he passed three different stones after riding multiple times."

This resulted in Wartinger going out and testing the theory.

Using a validated, synthetic 3D model of a hollow kidney complete with three kidney stones no larger than four millimetres inserted into the replica, he took the model in a backpack on Big Thunder Mountain at the theme park 20 times.

His initial results verified patient reports.

"In the pilot study, sitting in the last car of the roller coaster showed about a 64 percent passage rate, while sitting in the first few cars only had a 16 percent success rate," he said.

An expanded study included riding the same roller coaster with multiple kidney models attached to the researchers.

They discovered even better results while sitting in the back of the coaster, with a passage rate of nearly 70 percent, and also found that both studies showed a 100 percent passage rate if the stones were located in the upper chamber of the kidney.

"In all, we used 174 kidney stones of varying shapes, sizes and weights to see if each model worked on the same ride and on two other roller coasters," Wartinger said.

"Big Thunder Mountain was the only one that worked. We tried Space Mountain and Aerosmith's Rock 'n' Roller Coaster and both failed."

Computer passwords just got ridiculously secure

Researchers have just found an ultra-secure way to protect your password. Photo / Vikram Iyer, University of Washington
Researchers have just found an ultra-secure way to protect your password. Photo / Vikram Iyer, University of Washington

Sending a password or secret code over airborne radio waves like WiFi or Bluetooth means anyone can eavesdrop, making those transmissions vulnerable to hackers who can attempt to break the encrypted code.

Now, US computer scientists and electrical engineers have devised a way to send secure passwords through the human body, using benign, low-frequency transmissions generated by fingerprint sensors and touchpads on consumer devices.

"Fingerprint sensors have so far been used as an input device," explains Assistant Professor Shyam Gollakota, of the University of Washington.

"What is cool is that we've shown for the first time that fingerprint sensors can be repurposed to send out information that is confined to the body."

These "on-body" transmissions offer a more secure way to transmit authenticating information between devices that touch parts of your body - such as a smart door lock or wearable medical device - and a phone or device that confirms your identity by asking you to type in a password.

The new technique leverages the signals already generated by fingerprint sensors on smartphones and laptop touchpads to transmit data in new ways.

"Let's say I want to open a door using an electronic smart lock," said co-lead author Merhdad Hessar.

"I can touch the doorknob and touch the fingerprint sensor on my phone and transmit my secret credentials through my body to open the door, without leaking that personal information over the air."

- NZ Herald

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