Scientists

Further news of note for beachgoers: This could be a bad year for stinging nettles in the Chesapeake Bay, a University of Maryland scientist says. Maggie Sexton, with the UM Center for Environmental Science , has been checking for jellyfish daily in the Choptank River at the Horn Point Environmental Laboratory near Cambridge. "The conditions are right to have a large population," she said. "We saw the first one two weeks ago, and now we're starting to see one every day," she said.

Inside a two-story, cylindrical metal structure at Aberdeen Proving Ground, scientists detonate a homemade bomb to take high-speed pictures of the shrapnel flying apart. Elsewhere on the Army installation in Harford County, soldiers train on radio jammers intended to render enemy remote controls useless. At still another location, inventors work on hand-held test kits that will enable troops to identify chemicals used by bomb makers. All of the activity is aimed at stopping the signature weapon of the enemy in Afghanistan and Iraq: the improvised explosive device, the IED, which has been responsible for more than half the American combat deaths over the past decade and many of the brain injuries and amputations.

First, the bad news: The Andromeda galaxy, an agglomeration of 1 trillion stars that is visible to the naked eye, is hurtling through space at 250,000 miles per hour — and it's coming right at us. What's more, NASA astronomers in Baltimore said Thursday, while Andromeda barrels into our Milky Way, a companion galaxy will join in what the space agency is billing as a "titanic collision. " Now, the good news: With Andromeda still 2.5 million light years away, the collision won't take place for another 4 billion years, the astronomers said.

Dr. Solbert "Sol" Permutt, a retired physiologist and teacher who helped expand the Johns Hopkins University School of Medicine's division of pulmonary and critical care medicine, died of esophageal cancer May 23 at Roland Park Place. The longtime Mount Washington resident was 87. "In terms of the lung, it is not an exaggeration to say that most of our current understanding of how blood flows through lung blood vessels and how air flows in and out of the airways can be attributed to Sol," said Dr. David B. Pearse, a Hopkins professor of medicine who lives in Ellicott City.

No one likes to get stuck with a needle. But it's the only way doctors can get blood to test for diabetes, anemia and numerous other health problems. Scientists at the Johns Hopkins University School of Nursing say there is a much less invasive and painless means of detecting illnesses in patients — spit. Like blood, spit contains proteins, hormones, enzymes and DNA that can be used to test for and combat disease. It is easy and inexpensive to collect and analyze, making it ideal for research.

Record-high water temperatures and a March sewage leak are contributing to a large algae bloom in the Baltimore harbor, bringing what is known as a "mahogany tide" of reddish-brown algae to the Middle Branch of the Patapsco River. The bloom is somewhat earlier and more severe than usual, scientists say, despite the fact that a developing drought has limited runoff pollution from feeding algae growth. Water testing conducted by the Maryland Department of Natural Resources shows skyrocketing levels of chlorophyll, the molecule plants use to turn sunlight into energy, and plummeting levels of oxygen in waters near Brooklyn and Cherry Hill.

In their quest to cure Baltimore's ailing harbor, advocates and authorities have tried one gadget after another: floating wetlands, a solar-powered aerator, even a trash wheel. Add now the "algal turf scrubber," a long wooden sluiceway through which harbor water is pumped over a bed of slimy green algae. The gutter, 350 feet long by a foot wide, uses native algae to strip nutrients, suspended sediment and carbon from water and inject oxygen into it before returning it to the harbor.

In their quest to cure Baltimore's ailing harbor, advocates and authorities have tried one gadget after another: floating wetlands, a solar-powered aerator, even a trash wheel. Add now the "algal turf scrubber," a long wooden sluiceway in which harbor water is pumped over a bed of slimy green algae. The ecological restoration firm Biohabitats and the Living Classrooms Foundation invited news media to see the contraption set up on a former chromium plant site in Fells Point. The gutter, 350 feet long by one foot wide, uses native algae to strip nutrients, suspended sediment and carbon from water and inject oxygen into it before returning it to the harbor.

Heavy spring rains, a hot summer and two major storms caused the Chesapeake Bay's overall health to worsen last year, scientists said Tuesday, though there apparently was a slight improvement in the Baltimore area's Patapsco and Back rivers, long considered among the bay's most degraded tributaries. The beleaguered bay saw its ecological grade slip from a C- in 2010 to D+ last year in an annual report card drawn up by the University of Maryland and the National Oceanic and Atmospheric Administration.

A monthly chance to learn from scientists who study the heavens at the Space Telescope Science Institute takes place tomorrow. The institute, on the campus of Johns Hopkins University at 3700 San Martin Drive, is hosting its regular lecture event at 8 p.m. Scientist Marcel Haas will give a lecture titled “ Growing Galaxies in Supercomputers .” If you can't make it, the Bloomberg telescope is also open to the public Friday evenings,...