Comparison of a photometric method with standardized methods of antifungal susceptibility testing of yeasts

We determined the fluconazole MICs for 101 clinical isolates of Candida and Cryptococcus neoformans using the macro- and microdilution methods recommended by the National Committee for Clinical Laboratory Standards. We compared the MICs obtained by these methods with those obtained by a photometric assay that quantified the reduction of 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) by viable fungi. The MIC determined by this method was defined as the highest fluconazole concentration associated with the first precipitous drop in optical density. For Candida, both the MTT and the microdilution methods demonstrated excellent agreement with the standard macrodilution method. The MTT method, however, generated MICs at 24 h that were comparable to those generated by the standard macrodilution method, whereas the microdilution method required 48 h. For C. neoformans, the levels of agreement between the MICs determined by the MTT and microdilution methods after 48 h and those determined by the standard 72-h macrodilution method were 94% (29 of 31) and 94% (29 of 31), respectively. The MTT method therefore provided results comparable to those of currently recommended methods and had the advantages of a more rapid turnaround time and potential adaptability to use as an automated system. Furthermore, the MICs determined by the MTT method were determined photometrically, thereby eliminating reader bias.     

Altered T-lymphocyte responsiveness to polyclonal cell activators is responsible for liver cell necrosis in alcohol-fed rats

The role of T-cell activation in alcoholic liver disease was investigated in rats fed alcohol and subsequently exposed to concanavalin A (Con A). Following Con A injection (20 mg/kg body weight), greater increases in liver-to-body weight ratio and ALT levels were observed at 12 and 24 hr in rats fed ethanol, compared with control rats fed sucrose. Furthermore, increases in serum interleukin-6 and tumor necrosis factor-alpha levels were noted in ethanol-fed rats, with maximal levels detected at 4 hr declining thereafter, but remaining above control levels at 24 hr. Analysis of T-cell subpopulations showed an increased percentage of CD4+, CD5+, and CD8+ T cells in blood from all groups, but not in liver perfusate. In contrast, a significant increase in the percentage of activated CD25+ T cells was detected in both blood and liver perfusate from rats fed ethanol even 24 hr after Con A injection. When CD4+ and CD8+ T cells from liver perfusate were cultured in the absence or presence of Con A, an increase in interleukin-6 and tumor necrosis factor-alpha production in supernatants was observed in ethanol-fed rats. In cultures stimulated with Con A, a 2- to 8-fold increase in cytokine production was detected, with intrahepatic CD4+ T cells being the major source. Immunohistological analysis revealed infiltration of CD4+ T cells around portal vein and central vein areas associated with fatty liver and severe hepatic necrosis. The results suggest that alcohol consumption induced a dysregulated T-cell population that mediated hepatic necrosis following polyclonal activation with Con A.     

Results from the Mars Global Surveyor Thermal Emission Spectrometer

The Thermal Emission Spectrometer spectra of low albedo surface materials suggests that a four to one mixture of pyroxene to plagioclase, together with about a 35 percent dust component provides the best fit to the spectrum. Qualitative upper limits can be placed on the concentration of carbonates (<10 percent), olivine (<10 percent), clay minerals (<20 percent), and quartz (<5 percent) in the limited regions observed. Limb observations in the northern hemisphere reveal low-lying dust hazes and detached water-ice clouds at altitudes up to 55 kilometers. At an aerocentric longitude of 224 degrees a major dust storm developed in the Noachis Terra region. The south polar cap retreat was similar to that observed by Viking.     

Brain stem reticular formation neuronal correlates of stimulus significance and behavior during discriminative avoidance conditioning in rabbits.

Recorded multiple-unit activity in the reticular formation (RF) of the midbrain and pons in 14 New Zealand white rabbits during discriminative conditioning of locomotor (wheel-running) avoidance behavior, to examine whether discriminative neuronal activity develops in the RF during discriminative avoidance conditioning, and, if so, what its relation is to the activity in the limbic cortical structures and to the behavior. The positive and negative conditional stimuli (CS+ and CS–) were pure tones of different auditory frequency, and the unconditioned stimulus/stimuli (UCS) was a constant-current footshock (1.5–2.5 mA) delivered through the grid floor of the wheel. The pontine, but not the midbrain, sites manifested development during behavioral acquisition, of brief-latency (10–40 msec) discriminative neuronal discharges (i.e., greater discharges to the CS+ than to the CS–). The greatest magnitude of the discriminative discharges in the rostral pontine loci occurred in the 1st conditioning session. The discriminative response in the caudal loci developed more slowly, and it persisted to the criterial stage of training. Both rostral and caudal pontine loci, during the interval from CS onset to UCS onset, manifested a progressive build-up of neuronal firing in anticipation of the behavioral response. (59 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pulse tube cooler for flight hyperspectral imaging

A new version of TRW's miniature pulse tube cooler system maintains the short wave infrared–focal plane array (SWIR–FPA) (with wavelength spectrum of 0.9–2.5 μm in the hyperspectral imaging spectrometer for the Hyperion Instrument) interface at a temperature of 110 K. The cooler provides the nominally required cooling load of 0.84W to the FPA via a cold thermal strap, at 72% stroke consuming 14.7 W of electrical power, when the heat reject temperature is at 300 K. This cooler can operate up to 90% stroke, having 1.5 W cooling load, thus having 79% performance margin for the Hyperion mission. Before the installation and operation of the cooler onto the instrument, both the mechanical and the electronics assemblies underwent the environmental tests of launch vibration, thermal vacuum cycling, and burn-in. The cooler performance in terms of mechanical efficiency, electronics efficiency, load lines, temperature stability, self-induced vibrational force reduction, ripple current reduction, and magnetic radiated emission was measured and are reported here.     

Dynamic spectrum access using the interference temperature model

To combat spectral overcrowding, the FCC investigated new ways to manage RF resources. The idea was to let people use licensed frequencies, provided they can guarantee interference perceived by the primary license holders will be minimal. With advances in software and cognitive radio, practical ways of doing this are on the horizon. In 2003, the FCC released a memorandum seeking comment on the interference temperature model for controlling spectrum use. Analyzing the viability of this model and developing a medium access protocol around it are the main goals of this article. A model consisting of interference sources, primary licensed users, and secondary unlicensed users is modeled stochastically. If impact on licensed users is defined by a fractional decrease in coverage area, and this is held constant, the capacity achieved by secondary users is directly proportional to the number of unlicensed nodes, and is independent of the interference and primary users’ transmissions. Using the basic ideas developed in the system analysis, interference temperature multiple access, a physical and data-link layer implementing the interference temperature model, was formulated, analyzed, and simulated. A system implementing this model will measure the current interference temperature before each transmission. It can then determine what bandwidth and power it should use to achieve a desired capacity without violating an interference ceiling called the interference temperature limit. Ultimately, the resulting performance from the interference temperature model is low, compared to the amount of interference it can cause to primary users. Partly due to this research, in May 2007, the FCC rescinded its notice of proposed rule-making implementing the interference temperature model.     

建设核心网,为3G作好准备

介绍在同一数据核心网中如何支持不同代的网络,以实现２Ｇ向３Ｇ的过渡;指出发展基于分组／信元的核心交换网,为３Ｇ设备和服务的展开做好准备的时机已经到来;说明如何提高数据与语音业务容量,使运营商能够向３Ｇ基础用户群提供服务。     

Estimation and application of EMG amplitude during dynamiccontractions

The sections above have described an EMG amplitude estimator and an initial application of this estimator to the EMG-torque problem. The amplitude estimator consists of six stages. In the first stage, motion artifact and power-line interference are attenuated. Motion artifact is typically removed with a highpass filter. Elimination of power-line noise is more difficult. Commercial systems tend to use notch filters, accepting the concomitant loss of "true" signal power in exchange for simplicity and robustness. Adaptive methods may be preferable, however, to preserve more "true" signal power. In stage two, the signal is whitened. One fixed whitening technique and two adaptive whitening methods were described. For low-amplitude levels, the adaptive whitening technique that includes adaptive noise cancellation may be necessary. In stage three, multiple EMG channels (all overlying the same muscle) are combined. For most applications, simple gain normalization is all that is required. Stage four rectifies the signal and then applies the power law required to demodulate the signal. In stage six, the inverse of the power law is applied to relinearize the signal. Direct comparison of MAV (first power) to RMS (second power) processing demonstrates little difference between the two. Therefore, unless there is reason to believe that the EMG density departs strongly from that found in the existing studies, RMS and MAV processing are essentially identical. In stage five, the demodulated samples are averaged across all channels and then smoothed (time averaged) to reduce the variance of the amplitude estimate, but at the expense of increasing the bias. For best performance, the window length that best trades off variance and bias error is selected. The advanced EMG processing was next applied to dynamic EMG-torque estimation about the elbow joint. Results showed that improved EMG amplitude estimates led to improved EMG-torque estimates. An initial comparison of different system-identification techniques and model orders was reported. It is expected that these advanced processing and identification algorithms will also improve performance in other EMG applications, including myoelectrically controlled prostheses, biofeedback, and ergonomic assessment.     

PHASE EQUILIBRIA IN THE H2/CH4 SYSTEM AT TEMPERATURES FROM 92.3 TO 180.0 K AND PRESSURES TO 140 MPa*

Experimental measurements of liquid-vapor phase equilibria in the system H₂/CH₄ are reported for ten temperatures in the range 92.3 to 180 K, and pressures to 140 MPa. The mixture critical line and the pressure-temperature trace of the three-phase region solid-liquid-vapor have been located. The three-phase region and the critical line intersect at T = 91.5 K and P = 147 MPa to form an upper critical end point. Experimental results have been compared with predictions of three equations of state, Peng-Robinson, Reclich-Kwong and Deiters, and with calculations based on statistical mechanical perturbation theory.