Posts Tagged ‘channels’
Shrinking the size of tests – and their cost – down to pennies
While other scientists successfully shrank beakers, tubes and centrifuges into diagnostic laboratories that fit into aluminum boxes that cost $50,000, George Whitesides had smaller dreams. The diagnostic tests designed in Dr. Whitesides’s Harvard University chemistry laboratory fit on a postage stamp and cost less than a penny.
His secret? Paper.
His colleagues miniaturized diagnostic tests so they could move into the field with tiny pumps and thread-thin tubes. Dr. Whitesides opted for a more novel approach, reasoning that a drop of blood or urine could wick its way through a square of filter paper without any help.
And if the paper could be etched with tiny channels so that the drop followed a path, and if that path were mined with dried proteins and chemically triggered dyes, the thumbnail-size square could be a mini-laboratory — one that could be run off by the thousands on a Xerox machine.
Diagnostics for All, the private company Dr. Whitesides founded four years ago here in Boston’s Brighton neighborhood to commercialize his inspirations, has already created such a test for liver damage. It requires a single drop of blood, takes 15 minutes and can be read by an untrained eye: If a round spot the size of a sesame seed on the paper changes to pink from purple, the patient is probably in danger.
Using paper in diagnostic tests is not entirely new. It soaks up urine in home pregnancy kits and blood in home diabetes kits. But Dr. Whitesides has patented ways to control the flow through multiple layers for ever-more-complex diagnoses. His test has proved more than 90 percent accurate on blood samples previously screened by the laboratory of Beth Israel Deaconess Medical Center, a Harvard teaching hospital, said Una S. Ryan, chief executive of Diagnostics for All…
The initial target audience is AIDS patients with tuberculosis who must take powerful cocktails of seven or more drugs. Some drugs damage the liver, and deaths from liver failure are 12 times as common among African AIDS patients as among American ones, Dr. Ryan said, because current liver tests are expensive and require tubes of blood…
RTFA. Truly worthwhile effort, starting with grants from the Bill and Melinda Gates foundation and carrying through to government assistance both sides of the pond.
Taking the cost of tests from dollars to pennies makes them affordable in the 3rd World – as well as the growing pool of poverty in the industrial West. Many examples, many goals already met. The sort of medical research that doesn’t make billions for pharmaceutical giants; but, helps human beings worldwide.
Strange clouds form when aircraft inadvertently cause precipitation
As turboprop and jet aircraft climb or descend under certain atmospheric conditions, they can inadvertently seed mid-level clouds and cause narrow bands of snow or rain to develop and fall to the ground, new research finds.
Through this seeding process, they leave behind odd-shaped holes or channels in the clouds, which have long fascinated the public.
The key ingredient for developing these holes in the clouds: water droplets at subfreezing temperatures, below about 5 degrees Fahrenheit (-15 degrees Celsius). As air is cooled behind aircraft propellers or over jet wings, the water droplets freeze and drop toward Earth.
“Any time aircraft fly through these specific conditions, they are altering the clouds in a way that can result in enhanced precipitation nearby,” says Andrew Heymsfield, a scientist with the National Center for Atmospheric Research (NCAR) and lead author of a new study into the phenomenon.
“Just by flying an airplane through these clouds, you could produce as much precipitation as with seeding materials along the same path in the cloud…”
As far back as the 1940s, scientists have wondered about the causes of these clouds with gaps seemingly made by a giant hole punch. Researchers have proposed a number of possible aviation-related causes, from acoustic shock waves produced by jets, to local warming of the air along a jet’s path, to the formation of ice along jet contrails.
Indeed, the earliest observations implicated jet aircraft, but not propeller aircraft, as producing the holes.
Researchers in the 1980s observed that propeller aircraft could transform supercooled droplets into ice crystals, and experiments were launched in the 1990s to characterize the phenomenon.
RTFA – for the tale of how one group of researchers had the data they needed to understand this process – fall into their laps.
