The pe rmea t ion o f monova len t cations th rough the cGMP-gated channel of catfish cone ou te r segments was examined by measur ing permeabi l i ty and conduc tance ratios u n d e r bi ionic condit ions. For monova len t cations presented on the cytoplasmic side of the channel , the permeabi l i ty ratios with respect to extracel lular Na followed the sequence NH4 > K > Li > Rb = Na > Cs whi...

A Ca2+-blockable monova len t cat ion channel is p resen t in the apical m e m b r a n e o f the ec tode rm of the gastrulat ing chick embryo. We used the patch c lamp technique to study several s ingle-channel pe rmea t ion proper t ies o f this channel . In symmetrical condi t ions without Ca z+, the Na + cur ren t car r ied by the channe l rectifies inwardly. The channe l has an a p p a r e ...

T h e d y n a m i c a l p r o p e r t i e s of a n a q u e o u s a m m o n i u m chlor ide solut ion h a v e been ca lcu la ted f r o m a molecu la r d y n a m i c s s i m u l a t i o n ove r 3.5 p icoseconds a t a t e m p e r a t u r e of 301 K whe re t h e basic per iodic c u b e c o n t a i n e d 200 w a t e r molecules, 8 a m m o n i u m ions a n d 8 chloride ions. T h e effect ive pa i r p...

A nswer: Occluded VADs are not a minor problem, with an estimated 3%–70% failing to yield a blood sample (Mayo, 2001; Rihn, 2001; Whitman, 1996). Partial occlusion exists when a catheter flushes easily but will not aspirate blood. Total occlusion is characterized by the inability to withdraw blood or infuse fluid. Occlusions can occur from a fibrin tail, fibrin sheath, intraluminal thrombus, mu...

I N T R O D U C T I O N T e n s i o n d e v e l o p m e n t d u r i n g an i s o m e t r i c t e t a n u s in ske le ta l musc le occu r s in t h r e e d i s t inc t phases : t en s ion ini t ia l ly r ises r a p i d l y , t h e n c l imbs m o r e s lowly, a n d f ina l ly r e a c h e s a p l a t e a u which lasts m a n y s e c o n d s . T h i s t i m e c o u r s e is o b s e r v e d d u r i n ...

Mate, an infusion containing caffeine (3 g/liter), is drunk hot by most Uruguayan, North Argentinian, and South Brazilian people. This beverage has been recently associated with esophageal cancer in Brazil and Uruguay. To test the mutagenic and lethal effects of mate infusion, caffeine, hyperthermia, and their combinations, we used Saccharomyces cer. evisiae as an eucaryotic model system measur...

Optical studies of single molecules in ambient environments, which have led to broad applications, are primarily based on fluorescence detection. Direct detection of optical absorption with single-molecule sensitivity at room temperature is difficult because absorption is not a background-freemeasurement and is often complicated by sample scattering. Here we report ground-state depletionmicrosc...

The anti-inflammatory and analgesic effects of salicylates have been observed for centuries, but their mode of action remains obscure. Their recommendation as the cheapest and often the safest medicament in rheumatoid arthritis (Ragan, 1949) and in rheumatic fever (McEwen, 1954; Coburn, 1943) has led to renewed efforts to discover how they work. Salicylates and cortisone may act similarly in st...

The Stanford Linear Collider (SLC)1*2 accelerates ingle bunches of electrons and positrons to 47 GeV per beam and collides them with small beam sizes and at high currents. The beam emittances and intensities required for present operation have significantly extended traditional beam quality limits. The electron source produces over lo1 1 ein each of two bunches. The damping rings provide couple...

The s ingle most c r i t i c a l f a c t o r a f f e c t i n g t h e h e a l t h and s a f e t y o f workers engaged i n t h e coa l -winning p r o c e s s i s the mine envi ronment ; which i s b r o a d l y d e f i n e d as t h e space i n which man works when underground and i n c l u d e s t h e p h y s i c a l and c h e m i c a l c o n d i t i o n s of t h e s u r r o u n d i n g e n c l o ...