Improving the quality of shortwave broadcast reception indoors byusing an anti-fading probe antenna

When shortwave (SW) broadcasts are received on self-contained receivers indoors, there generally is a reduction in signal strength and an increase in the speed and depth of fading in comparison with reception in open spaces outdoors. Even when the received signal level is adequate, the quality of reception indoors is degraded. This comes about because the fields indoors are a superposition of components of radiated signal from the distant transmitter plus other components representing energy reradiated or scattered by nearby conductors such as house wiring or plumbing. Since many of the near-field components originate very close to the receiver, it is possible to reduce their effect by deriving the receiver input from two or more probes-i.e., pickup devices specially designed to respond to fields in their immediate vicinity without disturbing those fields. To achieve the desired probe action, advantage can be taken of the high input impedance of portable, battery-powered receivers designed for use with small telescoping whip antennas. Spacing of multiple probes in the order of a few tens of centimeters suffices to give an output significantly smoother and of higher quality than that obtainable with the receiver's whip antenna by itself. The high signal levels of many SW broadcasts make it practical to use small, inefficient antennas. This article describes an Anti-Fading Probe Antenna (APA), which produces a worthwhile improvement in reception quality indoors. It is simple to build, requires no adjustment, and may even improve received signal quality in some outdoor situations     

Arousal, numbing, and intrusion: symptom structure of PTSD following assault

OBJECTIVE: This study investigated hypotheses concerning the importance of symptoms of numbing in posttraumatic stress disorder (PTSD). METHODS: Symptoms of PTSD were assessed in 72 female rape victims and 86 female victims of nonsexual assault approximately 3 months after the crimes occurred. A principal-components factor analysis of subjects' symptoms was then undertaken. RESULTS: The analysis yielded three factors: arousal/avoidance, numbing, and intrusion. These were somewhat different from the symptom clusters in DSM-III-R, since effortful avoidance and numbing symptoms did not load on the same factor. Numbing symptoms appeared to be particularly important in identifying individuals with PTSD. CONCLUSIONS: The results imply that there are two patterns of posttrauma symptoms, one characterizing PTSD and the second characterizing a phobic reaction.     

Oxidation of low density lipoprotein by iron or copper at acidic pH

Oxidized low density lipoprotein (LDL) may play a significant role in atherosclerosis. We have investigated the effect of pH on the oxidation of LDL by iron or copper. When LDL was oxidized by iron in the presence of cysteine in either Hanks' balanced salt solution (HBSS) or Ham's F-10 medium, an acidic pH greatly decreased the lag period and increased the rate of formation of hydroperoxides and thiobarbituric acid-reactive substances (TBARS), and increased its uptake by macrophages. There was a dose-dependent increase of LDL oxidation at acidic pH in the presence of increasing concentrations of cysteine. When LDL was oxidized by copper in HBSS, an acidic pH increased the lag phase before the rapid formation of conjugated dienes, hydroperoxides, and TBARS, but increased its uptake by macrophages. Similar results were obtained using Ham's F-10 medium. Cysteine (100 microM) inhibited the modification of LDL by copper in HBSS at both pH 7.4 and 5.5 As atherosclerotic lesions may be acidic, these observations may help to explain why LDL oxidation occurs locally at these sites.     

A multichannel neural probe for selective chemical delivery at thecellular level

A bulk-micromachined multichannel silicon probe capable of selectively delivering chemicals at the cellular level as well as electrically recording from and stimulating neurons in vivo has been developed. The process buries multiple flow channels in the probe substrate, resulting in a hollow-core device, Microchannel formation requires only one mask in addition to those normally used for probe fabrication and is compatible with on-chip signal-processing circuitry. Flow in these microchannels has been studied theoretically and experimentally. For an effective channel diameter of 10 μm, a channel length of 4 mm, and water as the injected fluid, the flow velocity at 11 torr is about 1.3 mm/s, delivering 100 pl in 1 s. Intermixing of chemicals, with the tissue fluid due to natural diffusion through the outlet orifice becomes significant for dwell times in excess of about 30 min, and a shutter is proposed for chronic use. The probe has been used for acute monitoring of the neural responses to various chemical stimuli in guinea pig superior and inferior colliculus     

Convection in a concentric annulus with heat generating porous media and a permeable inner boundary

The effects of a permeable inner boundary on the maximum temperature and the convective flows were investigated numerically for a two-dimensional horizontal annulus containing a uniformly heat generating porous media. The time-dependent governing equations were nondimensionalized and put into an explicit finite difference numerical form. The finite difference equations were obtained from truncated Taylor series expansions using a central differencing scheme. Nondimensional temperatures and streamlines were obtained for heat generation rates ranging from 20 to 1,500 W/m³ corresponding to a range of modified Rayleigh numbers of 324 to 24,340 and for several combinations of isothermally heated wall conditions for annuli of radius ratio of 2. It was found that multi-cellular flows occur at the highest Rayleigh numbers investigated.     

Prolonged poststrike elevation in tongue-flicking rate with rapid onset in gila monster,Heloderma suspectum: Relation to diet and foraging and implications for evolution of chemosensory searching

Experimental tests showed that poststrike elevation in tongue-flicking rate (PETF) and strike-induced chemosensory searching (SICS) in the gila monster last longer than reported for any other lizard. Based on analysis of numbers of tongue-flicks emitted in 5-min intervals, significant PETF was detected in all intervals up to and including minutes 41–45. Using 10-min intervals, PETF lasted though minutes 46–55. Two of eight individuals continued tongue-flicking throughout the 60 min after biting prey, whereas all individuals ceased tongue-flicking in a control condition after minute 35. The apparent presence of PETF lasting at least an hour in some individuals suggests that there may be important individual differences in duration of PETF. PETF and/or SICS are present in all families of autarchoglossan lizards studied except Cordylidae, the only family lacking linguallly mediated prey chemical discrimination. However, its duration is known to be greater than 2-min only in Helodermatidae and Varanidae, the living representatives of Varanoidea. That prolonged PETF and SICS are typical of snakes provides another character supporting a possible a varanoid ancestry for Serpentes. Analysis of 1-min intervals showed that PETF occurred in the first minute. A review of the literature suggests that a pause in tongue-flicking and delay of searching movements are absent in lizards and the few nonvenomous colubrid snakes tested. The delayed onset of SICS may be a specific adaptation of some viperid snakes to allow potentially dangerous prey to be rendered harmless by venom following voluntary release after envenomation and preceding further physical contact with the prey.