16 April 2015
Guttation is the exudation of drops of xylem sap on the tips or edges of leaves of some vascular plants, such as grasses. Guttation is not to be confused with dew, which condenses from the atmosphere onto the plant surface.Reposted in amended form from 2009.
At night, transpiration usually does not occur because most plants have their stomata closed. When there is a high soil moisture level, water will enter plant roots, because the water potential of the roots is lower than in the soil solution. The water will accumulate in the plant, creating a slight root pressure. The root pressure forces some water to exude through special leaf tip or edge structures, hydathodes or water glands, forming drops.
Girolami et al. (2005) found that guttation drops from corn plants germinated from neonicotinoid-coated seeds could contain amounts of insecticide constantly higher than 10 mg/l, and up to 200 mg/l for the neonicotinoid imidacloprid. Concentrations this high are near those of active ingredients applied in field sprays for pest control and sometimes even higher. It was found that when bees consume guttation drops collected from plants grown from neonicotinoid-coated seeds, they die within a few minutes. This phenomenon may be a factor in bee deaths and, consequently, colony collapse disorder (CCD).
From an only-slightly-tongue-in-cheek op-ed piece in the StarTribune:
We defied danger on a daily basis. We never knew that we were doing risky things, of course; we just thought that we were having fun. Nonetheless, we spent our days immersed in activities that we’d never for a second allow our children or grandchildren to do...More at the link. I'll affirm that almost all of those applied to my childhood.
For most parents, the notion of baby-proofing a home was to close the cellar door so the kids wouldn’t fall down the stairs... Cover unused electrical outlets?... And why would anyone but a masochist put medicine into bottles that you couldn’t open...
We hurled lawn darts with reckless abandon... We also played with wood-burning kits... And there was a line of electric toy irons, including a model that, the ads assured, heated up to “only 250 degrees”...
Not only did we not wear helmets, we’d never even heard of them. Bikes came with a single reflector on the back, but it broke off and rarely was replaced... There were no bike paths or lanes offering a buffer from traffic...
We rode our bikes (helmetless) down busy streets, zipping from one friend’s house to another, never telling anyone where we were going next (as if we knew). We went swimming, climbed trees and played with firecrackers without so much as a casual glance in our direction by an adult...
We crowded into cars that had no seat belts... The concept [of secondhand smoke] didn’t exist yet. We just figured that smoke was part of the atmosphere — and it was in most homes... [Sunblock] was worn only by lifeguards...
13 April 2015
"Geometric whirlpools" are discussed in a Nature article:
Researchers at the Technical University of Denmark in Lyngby have created similar geometric shapes (holes in the form of stars, squares, pentagons and hexagons) in whirlpools of water in a cylindrical bucket. The shapes appear easily enough once the bucket is spinning at a rate of one to seven revolutions per second, they say.But the researchers admit their studies may not be relevant to planetary-sized systems.
Photo via the Space subreddit.
It shouldn't be this way -
From Saturday until the video surfaced Tuesday, Scott’s killing was being portrayed by city officials as simply what Slager said it was: a case of an officer facing down a violent black man, afraid for his life. The video showed us that story was the opposite of the truth...More details here.
The young immigrant from the Dominican Republic explained that he didn’t reveal that he had shot the video right away. Then he read the police report, which peddled Slager’s story about Scott posing a threat, and “it wasn’t like that, the way they are saying.”..
... he “thought about erasing the video” recorded via cell phone on his way to work, because “I felt like my life with this information would be in danger.”..
About five years ago when I blogged an explanation of Paul McCartney's phrase "Mother Mary comes to me", reader Binho suggested that I write about Don McLean's "American Pie," and offered a link to an extensive analysis of those lyrics.
This past week McLean's notes from his writing of the lyrics were sold at auction, and the BBC used the occasion to revisit questions about the lyrics. "Who broke the church bells? Who was the jester who sang for the king and queen? And what really was revealed "the day the music died"?"
People in the US are accidentally drowning baby tortoises by mistaking them for turtle hatchlings and "releasing" them into the water. The Florida Fish and Wildlife Conservation Commission (FWC) says it knows of three "well-intentioned good Samaritans" who have made the error...Via Nothing To Do With Arbroath.
"Because gopher tortoises often nest in dunes adjacent to sea turtle nesting beaches, correct identification of these terrestrial animals is important before deciding what action, if any, is necessary... Gopher tortoises have toes, with claws on each toe. Sea turtles have flippers."
A WaPo op-ed piece offers reminders that government handouts are not limited to poor people. Consider, for example, the yacht tax deduction:
If you’ve got a boat and you’re paying interest on it, that interest is tax-deductible – provided your boat is really, really big. If it has sleeping quarters, a kitchen and a toilet – e.g., it is a yacht – then it can be considered a second home and any interest you pay on it is deductible. But if you just have a garden-variety fishing boat or canoe, sorry – no deduction for you.The embedded image is real - a 196 foot yacht featured in this collection of photos.
From Collector's Weekly:
Seaweed collecting embodied a cross-section of Victorian-era pursuits, allowing people to explore nature, improve their scientific knowledge, and create an attractive memento to decorate their homes. By the 1840s, several books on identifying and preserving seaweed had been published...
Both men and women participated in these cultural trends, and there were definitely male seaweed collectors. In fact, Mary Carrington’s album contains a calling card for a man named W. H. Gould onto which has been placed beside a tiny seaweed specimen. But while male collectors were able to join the ranks of the professional scientists, women were largely restricted to domesticated versions of the same occupations. They were encouraged to collect seaweed not as a scientific undertaking but as a sentimental hobby and a social accomplishment.
Part of the appeal was what a seaweed collection said about the collector. Anyone could appreciate and collect flowers, but painstakingly obtaining, preserving, and mounting seaweed specimens demonstrated patience, artistic talent, and the refined sensibilities necessary to appreciate the more subtle beauties of nature. Queen Victoria herself made a seaweed album as a young lady.
This depiction is by the Flemish artist Joos van Cleve (ca. 1525). I find it interesting that the artist was knowledgeable enough to depict a stab wound to the heart entering below the xiphoid. Modern artists (and movie directors and people) tend to depict a downward thrust through the parasternal area that is so well protected by ribs and cartilage.
Via The Reward of Cruelty.