Ultrafast long-wavelength photodetectors fabricated onlow-temperature InGaAs on GaAs

The authors report the first successful demonstration of a metal-semiconductor-metal photodetector (MSMPD) fabricated on low-temperature InGaAs grown on GaAs by molecular beam epitaxy (MBE) for long-wavelength fiber optic applications. Interdigitated MSMPDs with finger widths and spacings of 0.2, 0.5, 1.0, and 2.0 μm were tested using a femtosecond pulsed laser and high-speed electrooptic sampling. A FWHM pulsed response of 2 and 1.3 ps was measured for low-temperature In _0.25Ga_0.75As and In_0.35Ga_0.65As, respectively. The latter is the fastest response reported to data for a photodetector capable of detection to wavelengths as long as 1.3 μm     

Heat-induced elevation of ceramide in Saccharomyces cerevisiae via de novo synthesis

Sphingolipid-related metabolites have been implicated as potential signaling molecules in many studies with mammalian cells as well as in some studies with yeast. Our previous work showed that sphingolipid-deficient strains of Saccharomyces cerevisiae are unable to resist a heat shock, indicating that sphingolipids are necessary for surviving heat stress. Recent evidence suggests that one role for the sphingolipid intermediate ceramide may be to act as a second messenger to signal accumulation of the thermoprotectant trehalose. We examine here the mechanism for generating the severalfold increase in ceramide observed during heat shock. As judged by compositional analysis and mass spectrometry, the major ceramides produced during heat shock are similar to those found in complex sphingolipids, a mixture of N-hydroxyhexacosanoyl C18 and C20 phytosphingosines. Since the most studied mechanism for ceramide generation in animal cells is via a phospholipase C-type sphingomyelin hydrolysis, we examined S. cerevisiae for an analogous enzyme. Using [3H]phytosphingosine and [3H]inositol-labeled yeast sphingolipids, a novel membrane-associated phospholipase C-type activity that generated ceramide from inositol-P-ceramide, mannosylinositol-P-ceramide, and mannose(inositol-P)2-ceramide was demonstrated. The sphingolipid head groups were concomitantly liberated with the expected stoichiometry. However, other data demonstrate that the ceramide generated during heat shock is not likely to be derived by breakdown of complex sphingolipids. For example, the water-soluble fraction of heat-shocked cells showed no increase in any of the sphingolipid head groups, which is inconsistent with complex sphingolipid hydrolysis. Rather, we find that de novo ceramide synthesis involving ceramide synthase appears to be responsible for heat-induced ceramide elevation. In support of this hypothesis, we find that the potent ceramide synthase inhibitor, australifungin, completely inhibits both the heat-induced increase in incorporation of [3H]sphinganine into ceramide as well as the heat-induced increase in ceramide as measured by mass. Thus, heat-induced ceramide most likely arises by temperature activation of the enzymes that generate ceramide precursors, activation of ceramide synthase itself, or both.     

The impact of gun control on suicide and homicide across the life span.

One tactic which has been suggested to prevent suicide and homicide is to restrict the availability of lethal means for these acts. The effectiveness of this tactic over the life span was explored by examining the impact of the passage of gun control legislation in Canada in 1977 (Bill c-51). The results indicated that, while the use of firearms for suicide was reduced a little after passage of this Act, this effect was not apparent for those over the age of 65. However, for homicide, the effect of the passage of the gun control legislation was stronger for victims over the age of 55. Several suggestions were made for future research on this topic. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Coaching executives.

Describes a systems-based approach to executive coaching that attempts to maximize the consideration of contextual factors. The case study of a 44-yr-old male executive illustrates this approach. The author notes that perhaps the greatest danger in coaching individuals from organizations in which there is no ongoing consulting relationship is the possibility that the psychologist may inadvertently participate in scapegoating by an organization or by a boss who is unable or unwilling to look deeply enough at the ways that the environment may be supporting the conditions underlying the individual's seemingly maladaptive response. The more removed the coaching is from the organizational context, the more pains the psychologist must take to ensure that the context is woven into the fabric of the coaching relationship and that the organization be persuaded that it, too, needs to play a role in defining and achieving the desired outcome. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The influence of COD,hydraulic, temperature and pH shocks on the stability of an unheated fluidised bed reactor

An anaerobic fluidised bed reactor, operating at room temperature, was used to treat a synthetic meat extract wastewater with an influent COD of 1250 mg 1^–1. It was subjected to large increases in influent COD and flow rate for 4-and 8-h periods. The reactor tolerated these transient changes satisfactorily and with no long term detrimental effects. Normal operation was regained within 9h. Variations in operating temperature and influent pH were also examined. Four hour duration, 10°C temperature increases and decreases had little effect on effluent quality, but long term operation at a low influent pH was considered inadvisable. A simulated working week experiment was carried out with a 48-h 90% influent flowrate reduction, followed by a return to normal operation. The reactor tolerated these conditions well, with full recovery made within a few hours. The resistance of the reactor to unfavourable process conditions is discussed. The extrapolation of laboratory data to practical operating conditions is also considered.     

The role of the therapeutic alliance in psychotherapy.

Traces the development of the concept of the therapeutic working alliance from its psychodynamic origins to current pantheoretical formulations. Research on the alliance is reviewed under 4 headings: the relation between a positive alliance and success in therapy, the path of the alliance over time, the examination of variables that predispose individuals to develop a strong alliance, and the exploration of the in-therapy factors that influence the development of a positive alliance. Important areas for further research are also noted. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

IV. Yeast sequencing reports. GUF1, a gene encoding a novel evolutionarily conserved gtpase in budding yeast

While sequencing a region of chromosome IV adjacent to the checkpoint gene MEC3, we identified a gene we call GUF1 (G TPase of U nknown F unction), which predicts a 586 amino acid GTPase of the elongation factor-type class. The predicted Guf1p protein bears striking sequence similarity to both LepA from Escherichia coli (43% identical) and LK1236·1 from Caenorhabditis elegans (42% identical). Analysis of both a guf1δ deletion and a putative constitutive-activating mutant (GUF1HG) revealed that GUF1 is not essential nor did mutant cells reveal any marked phenotype. The GenBank Accession Number for the GUF1 sequence is U22360.