Enhanced high-frequency performance in a GaAs, self-aligned, n-JFETusing a carbon buried p-implant

C ion implantation has been employed, for the first time, to form the buried p-layer in GaAs, self-aligned, ion implanted JFETs. Comparable DC performance was seen for JFETs with C or Mg implants; however, C-backside JFETs showed superior high-frequency performance. High dose C-backside devices had a f_t of 28.3 GHz and a f_max of 43.2 GHz for a 0.5 μm gate length that were 28% and 46% higher, respectively, than comparable Mg-implanted JFETs. This enhancement is a result of the lower C_gs in the C-backside device resulting from he inherently low activation of the implanted C below the channel while the C still effectively compensated the tail of the Si-channel implant. This approach relaxes the trade-off between optimizing the DC and the AC performance for the buried p-implant in GaAs JFETs and MESFET's     

Catalytic contribution of flap-substrate hydrogen bonds in "HIV-1 protease" explored by chemical synthesis

An analogue of "HIV-1 protease" was designed in which the ability to donate important water-mediated hydrogen bonds to substrate was precisely and directly deleted. Chemical ligation of unprotected peptide segments was used to synthesize this "backbone-engineered" enzyme. The functionally relevant amide -CONH- linkage between residues Gly49-Ile50 in each flap of the enzyme was replaced by an isosteric thioester -COS- bond. The backbone-engineered enzyme had normal substrate specificity and affinity (Km). However, the catalytic activity (kcat) was reduced approximately 3000-fold compared to the native amide bond-containing enzyme. Inhibition by the reduced peptide bond substrate analogue MVT-101 was unaffected compared with native enzyme. By contrast, the normally tight-binding hydroxyethylamine inhibitor JG-365 bound to the backbone-engineered enzyme with an approximately 2500-fold reduction in affinity. The reduced catalytic activity of the -Gly49-psi(COS)-Ile50-backbone-engineered enzyme analogue provides direct experimental evidence to support the suggestion that backbone hydrogen bonds from the enzyme flaps to the substrate are important for the catalytic function of the HIV-1 protease.     

A heterogeneous modular robotic design for fast response to a diversity of tasks

This paper describes a heterogeneous modular robot system design which attempts to give a quick solution to a diversity of tasks. The approach is based on the use of an inventory of three types of modules i.e., power and control module, joint module and specialized module. Each module type aims to balance versatility and functionality. Their design permits rapid and cost effective design and fabrication. They are interchangeable in different ways to form different robot or system configurations. Depending on the task, the operator decides what type of robot can provide the best performance within the mission. A spherical joint module is described and used to build different robots, hence, forward and inverse kinematics models are obtained. Finally, from the modules described in this work, several robot configurations such as robotic arms, leg-based robots and wheel-based robots are assembled to demonstrate the execution of manipulation and locomotion tasks.     

A mixed longitudinal and cross-sectional model to forecast the journal impact factor in the field of Dentistry

Scientometrics - In order to estimate the impact factor value for a journal in Dentistry, two sets of variables were considered in this study: the first takes in the longitudinal behavior of the...     

Manganese oxide thin-films for current-signal sensing and thermal insulation

Manganese oxide thin-films for current-signal sensing and thermal insulation were synthesized by high-vacuum evaporation and thermal oxidation processes at low-temperature conditions. Structure-formation of the films with orthorhombic-partial structure of MnO₂/Mn₂O₃ was investigated by X-ray diffraction. Raman studies have demonstrated that thermal properties can be influenced by the symmetry of the Mn–O bonds and it associated with the dynamic Jahn–Teller distortion. Dynamic behavior of samples as a function of the frequency response to verify their performance as signal sensors was evaluated by resistive–inductive circuit (RL circuit). To demonstrate the thermal capability of samples from current–voltage (I–V) characteristics, a Schottky emission model was used.     

Spatial Quality Evaluation of Pedestrian Streets

This paper presents an assessment of the spatial quality of a pedestrian street located in downtown Bauru, S~o Paulo State, Brazil, from the application of some urban sustainability indicators. Multi-method was used to evaluate the thermal comfort quality of users, urban accessibility and preservation of architectural heritage. The results show that the sustainability indicators, apart from being effective tools in identifying problems, can assist local managers in decision making, planning and monitoring of pedestrian public space. These indicators contribute to a broad diagnosis of the pedestrian street and also the formulation of programs, projects and municipal policies, aimed at providing a better life quality for pedestrians.     

Psychologists' Attitudes and Therapeutic Approaches Toward Gay, Lesbian, and Bisexual Issues Continue To Improve: An Update.

Psychologists' attitudes and approaches toward the gay, lesbian, and bisexual (GLB) lifestyle continue to change, on the basis of results from 437 responding members of the American Psychological Association. Psychologists are more likely to view an active GLB lifestyle-identity as acceptable and non-pathological, more likely to support and provide gay-affirmative therapy, and much less likely to support changing sexual orientation through psychotherapy. Female psychologists are significantly more likely to view a GLB lifestyle as accepting and to provide gay-affirmative therapy to GLB clients compared with their male counterparts. Finally, training opportunities for psychologists involving GLB issues appear to be increasing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial reconstruction of marker trajectories from high-speed video image sequences

Human neuroblastoma cells SK-N-SH express significant numbers of IL-1R type I on their surface, as detected by saturation binding and RT-PCR, and are responsive to IL-1beta activation by producing inflammatory cytokines IL-6 and IL-8. IL-1beta can also have an indirect effect on nervous cell functions, since it is able to modulate the stimulus-induced increase of intracellular Ca++ levels, one of the first steps of the cell activation mechanism. In fact, on SK-N-SH neuroblastoma cells, IL-1beta can inhibit the Ca++ increase induced by stimulation of acetylcholine receptors with carbachol. In parallel to IL-1beta, the neurotrophic factor CNTF also shows an inhibitory effect on carbachol-stimulated Ca++ increase in CNTFRalpha-expressing SK-N-SH cells. However, when simultaneously present, the two cytokines cross-inhibit, thus allowing full cell activation in response to the cholinoceptor agonist. The inhibitory effect of CNTF on IL-1beta activities on nervous cells was confirmed in the IL-6 production assay. In fact, while CNTF could not induce IL-6 production, it could strongly inhibit cytokine production in response to IL-1beta in SK-N-SH cells. The down-modulation of IL-1 effects by CNTF could be one of the mechanisms controlling the extent of the inflammatory reaction at the nervous system level.     

An all implanted self-aligned enhancement mode n-JFET with Zn gatesfor GaAs digital applications

An all implanted self-aligned n-channel JFET fabrication process is described where Zn implantation is used to form the p⁺ gate region. A refractory metal (W) gate contact is used to allow subsequent high temperature activation of the self-aligned Si source and drain implant. 0.7 μm JFET's have a maximum transconductance of 170 mS/mm with a saturation current of 100 mA/mm at a gate bias of 0.9 V. The p⁺/n homojunction gate has a turn on voltage of 0.95 V at a current of 1 mA/mm. The drain-source breakdown voltage is 6.5 V. Microwave measurements made at a gate bias of 1 V show an f_t of 19 GHz with an f_max of 36 GHz. These devices show promise for incorporation in both DCFL and complementary logic circuits     

Interlevel dielectric via etch process monitoring by atomic forcemicroscopy

The use of AFM for in-line monitoring of an interlevel dielectric via plasma etching step is reported. By comparing etch depths, to via types contacting both Au- and W-based metals, the AFM can non-destructively determine whether micrometre-sized vias have been cleared. Owing to the etch selectivity of the SF₆/O₂ plasma, the Au-based ohmic metal acts as an etch stop whereas the W-based refractory gate contact continues to etch