Novel Long‐Chain Diol Phospholipids from Some Bacteria Belonging to the Class Thermomicrobia

Polar lipids of bacteria from the class Thermomicrobia are known to contain long‐chain 1,2‐diols instead of glycerol, although the nature of polar head groups has not been investigated. We have studied phospholipid classes of two species from the class Thermomicrobia—Sphaerobacter thermophilus and Thermomicrobia sp. WKT50.2. TLC and ³¹P‐NMR analysis of polar lipids revealed that both S. thermophilus and Thermomicrobia sp. WKT50.2 contain the same set of four major phospholipid classes. Structures of the novel phospholipids in S.thermophilus were established as 2‐acylalkyldiol‐1‐O‐phosphoinositol, 2‐acylalkyldiol‐1‐O‐phosphoinositol mannoside, 2‐acylalkyldiol‐1‐O‐phospho‐acylmannoside, and 2‐acylalkyldiol‐1‐O‐phosphoinositol acylmannoside. To our knowledge, this is the first report of a phospholipid with a mannose directly bound to the phosphate. We also analyzed fatty acids and long‐chain 1,2‐diols of S. thermophilus and Thermomicrobia sp. WKT50.2 and compared our data with available information for T. roseum. All species share a similar set of fatty acids, with 12‐Me 18:0 being the major fatty acid. The major diol in S. thermophilus was identified as 13‐Me 19:0 (66.2 %). The 21:0 diol was the major component both in Thermomicrobia sp. WKT50.2 (50.6 %) and in T. roseum (56.6 %).     

Exploring the Substrate Promiscuity of Drug‐Modifying Enzymes for the Chemoenzymatic Generation of N‐Acylated Aminoglycosides

Aminoglycosides are broad‐spectrum antibiotics commonly used for the treatment of serious bacterial infections. Decades of clinical use have led to the widespread emergence of bacterial resistance to this family of drugs limiting their efficacy in the clinic. Here, we report the development of a methodology that utilizes aminoglycoside acetyltransferases (AACs) and unnatural acyl coenzyme A analogues for the chemoenzymatic generation of N‐acylated aminoglycoside analogues. Generation of N‐acylated aminoglycosides is followed by a simple qualitative test to assess their potency as potential antibacterials. The studied AACs (AAC(6′)‐APH(2′′) and AAC(3)‐IV) show diverse substrate promiscuity towards a variety of aminoglycosides as well as acyl coenzyme A derivatives. The enzymes were also used for the sequential generation of homo‐ and hetero‐di‐N‐acylated aminoglycosides. Following the clinical success of the N‐acylated amikacin and arbekacin, our chemoenzymatic approach offers access to regioselectively N‐acylated aminoglycosides in quantities that allow testing of the antibacterial potential of the synthetic analogues making it possible to decide which molecules will be worth synthesizing on a larger scale.     

The role of cue–target translation in backward inhibition of attentional set.

Backward inhibition (BI) refers to a reaction time cost incurred when returning to a recently abandoned task compared to returning to a task not recently performed. The effect has been proposed to reflect an inhibitory mechanism that aids transition from one task to another. The question arises as to precisely what aspects of a task may be inhibited and when the process takes place. Recent work has suggested a crucial role for response-related components of the task, which occur late in the typical trial structure (cue–target–response). In contrast to this suggestion, the authors present evidence that the way in which the task is cued can also modulate BI. Specifically, they find that the less transparent the cue–target relationship, the greater the level of BI. This also demonstrates that BI can be triggered at early stages of the trial structure, specifically during task preparation and prior to response processes. The authors conclude that BI is not tied to any particular component of the task structure but arises from whatever component generates the greatest intertrial conflict. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A 3.6-Gb/s point-to-point heterogeneous-voltage-capable DRAM interface for capacity-scalable memory subsystems

We describe a DRAM interface operating at 3.6 Gb/s/pin implemented in 130-nm CMOS logic and 110-nm DRAM process technologies. It utilizes simultaneous bidirectional (SBD) signaling in a daisy-chained (repeated), point-to-point configuration to enable high performance scalable memory subsystems; and also provides direct attach capability for DRAMs to memory controllers or other logic devices. Source-synchronous strobes are used for data capture, minimizing strobe-to-data jitter. A low-jitter differential clock retimes the data at each DRAM on a per DIMM basis preventing jitter from accumulating in repeated data. The phase of this clock is adjusted on each DRAM to minimize the latency of the repeaters. 80 mW of total power is dissipated per DRAM I/O at 3.6 Gb/s. We present results from a system using both memory controller and DRAM repeater test chips.     

Student opinions on an interactive arithmetic test

The aim of this study was to assess student attitudes towards an interactive arithmetic test. A sample of 45 primary school children from Years 1 and 2 in two Western Australian primary schools participated in the study. After using the test for a period of six weeks students were invited to detail what they liked and disliked about the test and how they might improve it. Analysis of this written feedback revealed a generally positive attitude towards the test. There were just a few negative responses, mainly pertaining to the slow speed of the program on the computers used in the study.     

Attentional Modulation of the Visual Motion Aftereffect Has a Central Cognitive Locus: Evidence of Interference by the Postcategorical on the Precategorical.

An attentionally demanding task undertaken during adaptation to motion reduces the duration of the subsequent motion aftereffect (A. Chaudhuri, 1990). Previous studies have suggested that this effect is intramodal in character, reflecting the selective deployment of visual attention. The present study demonstrates that nonvisual tasks, performed concurrently with motion adaptation, can significantly reduce the duration of the ensuing aftereffect. Three experiments converge on the conclusion that postcategorical processes can influence otherwise unrelated concurrent precategorical processes. The experiments also show that neither perceptual input nor motor output components of the attentional task are responsible for the subsequent reduction in motion of aftereffect. The results suggest a reappraisal of findings in this area and of the general distinction between perception and cognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Particle trajectories and terminal velocities in vertically oscillating fluids

The trajectories and terminal velocities of particles in vertically oscillating fluids have been studied by obtaining analytic and numerical solutions to the nonlinear Langevin equation representing a superposition of forces arising from particle acceleration, displaced fluid acceleration, buoyancy and particle-fluid drag as represented by an n^th-power drag law. In vibrating fluids the directional particle velocities are found to be lower than in stationary fluids for drag exponents n > 1 and correspondingly higher for 0 < n < 1. The engineering significance of the results is discussed in relation to hold-up, separation and transport phenomena in vertically oscillating multiparticle-fluid systems.     

Comparison of SF6 and Fluorescein as Tracers for Measuring Transport Processes in a Large Tidal River

We present the first large-scale comparison of a fluorescent dye [fluorescein (C20H10O5Na2)] and a gas [sulfur hexafluoride (SF6)] as tracers of advection and longitudinal dispersion from a dual tracer release experiment conducted in the tidal Hudson River. At the beginning of the experiment, 36?kg of fluorescein and ～ 4.3?mol of SF6 were injected into the Hudson River at an averaged depth of 9.5?m, ～ 1?m above the bottom, near Hyde Park, N.Y. After injection, fluorescein distributions were surveyed for 4 days (until it became undetectable) and SF6 distributions were surveyed for 10 days. The dye resolves initial vertical mixing on the day of injection, and then net advection and longitudinal dispersion, whereas SF6 provides information on net advection and longitudinal mixing on larger spatial scales and longer time scales. Quantitative estimates of transport processes (net advection and longitudinal dispersion) calculated from the two methods are consistent for the first three days, and start to deviate on the fourth day when the signal-to-noise ratio of the dye deteriorated.     

Hepatitis C virus heteroduplex tracking assay for genotype determination reveals diverging genotype 2 isolates in Italian hemodialysis patients

Recently, some empirical studies have shown an effect of body mass on take-off ability in birds, supporting the theory that birds with increased fat loads face a greater predation risk. Small wintering birds accumulate fat reserves of about 10% of their fat-free body mass during the day to survive long, cold, winter nights. Theoretically, mass-dependent predation risk could be an important factor affecting their daily foraging routines. I studied the take-off ability of wintering willow tits, Parus montanus, in relation to their fat load. Willow tits were on average 7.7% heavier at dusk than at dawn but there was no measurable effect of body mass on take-off ability. The results indicate that the relatively small fat loads accumulated during a day by willow tits do not increase the risk of predation as a consequence of reduced take-off ability. Copyright 1998 The Association for the Study of Animal Behaviour.