Optimum field theory design of broad-band E-plane branchguide phase shifters and 180° couplers

Optimum rectangular waveguide E-plane branch guide phase shifters and 180° branch guide couplers are designed with the rigorous method of field expansion into normalized eigenmodes. The design includes both the higher order mode interaction between the step discontinuities and the finite step and branch heights. The phase shifter design applies the Schiffman principle to branch guide couplers where two ports are short-circuited. The 180° coupler design combines the advantage of the broadband potential of multiple-branch couplers with the low-insertion-loss qualities of E-plane stub-loaded phase shifters. A computer-optimized phase shifter prototype for the waveguide Ku-band (12-18 GHz) shows a 90°±1° differential phase shift with reference to an empty waveguide within about 23% bandwidth. Five-branch three-stub coupler prototypes, designed for 3±0.2 dB coupling, for the waveguide Ku- and Ka-bands (26-40 GHz) achieve a 180°±1° differential phase shift at the output ports within about 19% bandwidth, as well as more than 30 dB isolation and return loss. The theory is verified by measured results     

31P NMR spectroscopy detects metabolic abnormalities in asymptomatic patients with hypertrophic cardiomyopathy

BACKGROUND: Hypertrophic cardiomyopathy (HCM) often causes sudden, unexpected death in adolescents and young adults. Alterations in myocardial metabolism are considered to be causes for contractile dysfunction. We examined the question of whether metabolic abnormalities antedate the manifestation of symptoms in patients with HCM. METHODS AND RESULTS: Proton-decoupled 31P NMR spectroscopy of the anterior left ventricular wall of the heart of 14 young, asymptomatic patients with HCM was performed with a 1.5-T whole-body imager. Spectra of the phosphate metabolites were compared with those of normal control subjects. The patients exhibited a significantly reduced (P<0.02) ratio of phosphocreatine (PCr) to ATP of 1.98+/-0.37 (mean+/-SD), compared with 2.46+/-0.53 obtained in 11 normal control subjects. In addition, the group of patients with severe hypertrophy of the interventricular septum (n=8) showed a significantly increased (P<0.05) Pi-to-PCr ratio, with a Pi x 100/PCr of 20.0+/-8.3 versus 9.7+/-7.2 in control subjects. Both abnormalities are similar to those found in ischemic myocardium. This view is also supported by a significantly increased (P<0.01) phosphomonoester (PME)-to-PCr ratio, with a PME x 100/PCr of 20.7+/-11.2 compared with 8.4+/-6.7 in control subjects, indicating altered glucose metabolism. CONCLUSIONS: 31P NMR spectroscopy detects alterations of myocardial metabolism in asymptomatic patients with HCM. These alterations may contribute to the understanding of the pathophysiology and natural history of the disease.     

Mode-matching CAD of rectangular or circular multiaperturenarrow-wall couplers

A rigorous and efficient mode-matching computer-aided design (CAD) method for rectangular waveguide H-plane couplers is presented. The couplers employ multiple large rectangular or circular apertures of different sizes and nonuniform distance. The decomposition of the coupler structure into adequate mode-matching key-building blocks, i.e., the T-junction, double-plane step discontinuity, and rectangular-to-circular waveguide transition, together with the homogeneous intermediate waveguide sections of finite lengths yield the desired high flexibility. Both the finite wall thickness and the higher order mode interaction between all discontinuities are accurately taken into account by the combination of the individual building blocks of the generalized scattering matrix technique. Design examples for rectangular and circular aperture provide coupling values of -10.7, -10, -8.1, -5.3, -4.7, -3, -2.6, and -2.3 dB in Ku-band (12-18 GHz), thus demonstrating the flexibility and the efficiency of the method. The theory is verified by excellent agreement with measurements     

Women and computers. Effects of stereotype threat on attribution of failure

This study investigated whether stereotype threat can influence women’s attributions of failure in a computer task. Male and female college-age students (n = 86, 16–21 years old) from Germany were asked to work on a computer task and were hinted beforehand that in this task, either (a) men usually perform better than women do (negative threat condition), or (b) women usually perform better than men do (positive condition), or (c) they received no threat or gender-related information (control group). The final part of the task was prepared to provide an experience of failure: due to a faulty USB-memory stick, completion of the task was not possible. Results suggest a stereotype threat effect on women’s attribution of failure: in the negative threat condition, women attributed the failure more internally (to their own inability), and men more externally (to the faulty technical equipment). In the positive and control conditions, no significant gender differences in attribution emerged.     

Potassium channel openers require ATP to bind to and act through sulfonylurea receptors

KATP channels are composed of a small inwardly rectifying K+ channel subunit, either KIR6.1 or KIR6.2, plus a sulfonylurea receptor, SUR1 or SUR2 (A or B), which belong to the ATP-binding cassette superfamily. SUR1/KIR6.2 reconstitute the neuronal/pancreatic beta-cell channel, whereas SUR2A/KIR6.2 and SUR2B/KIR6.1 (or KIR6.2) are proposed to reconstitute the cardiac and the vascular-smooth-muscle-type KATP channels, respectively. We report that potassium channel openers (KCOs) bind to and act through SURs and that binding to SUR1, SUR2A and SUR2B requires ATP. Non-hydrolysable ATP-analogues do not support binding, and Mg2+ or Mn2+ are required. Point mutations in the Walker A motifs or linker regions of both nucleotide-binding folds (NBFs) abolish or weaken [3H]P1075 binding to SUR2B, rendering reconstituted SUR2B/KIR6.2 channels insensitive towards KCOs. The C-terminus of SUR affects KCO affinity with SUR2B approximately SUR1 > SUR2A. KCOs belonging to different structural classes inhibited specific [3H]P1075 binding to SUR2B in a monophasic manner, with the exception of minoxidil sulfate, which induced a biphasic displacement. The affinities of KCO binding to SUR2B were 3.5-8-fold higher than their potencies for activation of SUR2B/KIR6.2 channels. The results establish that SURs are the KCO receptors of KATP channels and suggest that KCO binding requires a conformational change induced by ATP hydrolysis in both NBFs.     

Timing of organic carbon release from mountain pine beetle impacted ponderosa pine forests in South Dakota

The decay of mountain pine beetle (MPB) (Dendroctonus ponderosae) affected ponderosa pine (Pinus ponderosa) forests has increased organic carbon (OC) loading within the Rapid Creek watershed in the Black Hills of South Dakota, with total OC (TOC) concentrations up to 6.2 mg L^?1 observed in 2015. The impacts of large‐scale tree mortality on water quality were delayed. OC concentrations in the watershed correlated with recent MPB impact stage progression. Regional ponderosa pine forests that were 3 and 6 years after MPB infection (grey and snagfall phases) exhibited increased OC loading within the Rapid Creek watershed. A better understanding of regional watershed response patterns for MPB tree mortality may assist with mitigating ancillary water quality impacts.     

Masculinity causes speeding in young men

The goal of this study was to examine if masculinity is causally responsible for speeding in young men. Participants (83 males) were randomly assigned to a masculine, feminine, or neutral priming condition. Priming consisted in active listening to either masculine, feminine, or neutral words coming from the car radio while driving in a high-end driving simulator. Results showed that when the concept of masculinity was activated by priming, participants' driving speed increased significantly from the beginning to the end of the driving simulation as compared to the neutral and the feminine condition. Results are discussed with respect to real life health implications.