630-mV open circuit voltage, 12% efficient n-Si liquid junction

We report the first experimental observation of a semiconductor/liquid junction whose open circuit voltage Voc is controlled by bulk diffusion/recombination processes. Variation in temperature, minority-carrier diffusion length, and/or in majority-carrier concentration produces changes in the Voc of the n-Si/CH3OH interface in accord with bulk recombination/diffusion theory. Under AM2 irradiation conditions, the extrapolated intercept at 0 K of Voc vs T plots yields activation energies for the dominant recombination process of 1.1–1.2 eV, in accord with the 1.12-eV band gap of Si. A crucial factor in achieving optimum performance of the n-Si/CH3OH interface is assigned to photoelectrochemical oxide formation, which passivates surface recombination sites at the n-Si/CH3OH interface and minimizes deleterious effects of pinning of the Fermi level at the Si/CH3OH junction. Controlled Si oxide growth, combined with optimization of bulk crystal parameters in accord with diffusion theory, is found to yield improved photoelectrode output parameters, with 12.0±1.5% AM2 efficiencies and AM1 Voc values of 632–640 mV for 0.2-Ω cm Si materials

Architecture of the Short External Rotator Muscles of the Hip.

BackgroundMuscle architecture, or the arrangement of sarcomeres and fibers within muscles, defines functional capacity. There are limited data that provide an understanding of hip short external rotator muscle architecture. The purpose of this study was thus to characterize the architecture of these small hip muscles.MethodsEight muscles from 10 independent human cadaver hips were used in this study (n = 80 muscles). Architectural measurements were made on pectineus, piriformis, gemelli, obturators, quadratus femoris, and gluteus minimus. Muscle mass, fiber length, sarcomere length, and pennation angle were used to calculate the normalized muscle fiber length, which defines excursion, and physiological cross-sectional area (PCSA), which defines force-producing capacity.ResultsGluteus minimus had the largest PCSA (8.29 cm2) followed by obturator externus (4.54 cm2), whereas superior gemellus had the smallest PCSA (0.68 cm2). Fiber lengths clustered into long (pectineus - 10.38 cm and gluteus minimus - 10.30 cm), moderate (obturator internus - 8.77 cm and externus - 8.04 cm), or short (inferior gemellus - 5.64 and superior gemellus - 4.85). There were no significant differences among muscles in pennation angle which were all nearly zero. When the gemelli and obturators were considered as a single functional unit, their collective PCSA (10.00 cm2) exceeded that of gluteus minimus as a substantial force-producing group.ConclusionsThe key findings are that these muscles have relatively small individual PCSAs, short fiber lengths, and low pennation angles. The large collective PCSA and short fiber lengths of the gemelli and obturators suggest that they primarily play a stabilizing role rather than a joint rotating role

Magnetoconductance oscillations in quasiballistic multimode nanowires

We calculate the conductance of quasi-one-dimensional nanowires with electronic states confined to a surface charge layer, in the presence of a uniform magnetic field. Two-terminal magnetoconductance (MC) between two leads deposited on the nanowire via tunnel barriers is dominated by density-of-states (DOS) singularities, when the leads are well apart. There is also a mesoscopic correction due to a higher-order coherent tunneling between the leads for small lead separation. The corresponding MC structure depends on the interference between electron propagation via different channels connecting the leads, which in the simplest case, for the magnetic field along the wire axis, can be crudely characterized by relative winding numbers of paths enclosing the magnetic flux. In general, the MC oscillations are aperiodic, due to the Zeeman splitting, field misalignment with the wire axis, and a finite extent of electron distribution across the wire cross section, and are affected by spin-orbit coupling. The quantum-interference MC traces contain a wealth of information about the electronic structure of multichannel wires, which would be complimentary to the DOS measurements. We propose a four-terminal configuration to enhance the relative contribution of the higher-order tunneling processes and apply our results to realistic InAs nanowires carrying several quantum channels in the surface charge-accumulation layer.Comment: 11 pages, 8 figure

Imaging a 1-electron InAs quantum dot in an InAs/InP nanowire

Nanowire heterostructures define high-quality few-electron quantum dots for nanoelectronics, spintronics and quantum information processing. We use a cooled scanning probe microscope (SPM) to image and control an InAs quantum dot in an InAs/InP nanowire, using the tip as a movable gate. Images of dot conductance vs. tip position at T = 4.2 K show concentric rings as electrons are added, starting with the first electron. The SPM can locate a dot along a nanowire and individually tune its charge, abilities that will be very useful for the control of coupled nanowire dots

Changing family structures and self-rated health of India’s older population (1995-96 to 2014)

A common view within academia and Indian society is that older Indians are cared for by their families less than in the past. Children are a key source of support in later life and alternatives are limited, therefore declining fertility appears to corroborate this. However, the situation may be more complex. Having many children may be physiologically burdensome for women, sons and daughters have distinct care roles, social trends could affect support provision, and spouses also provide support. We assessed whether the changing structure of families has negatively affected health of the older population using three cross-sectional and nationally representative surveys of India’s 60-plus population (1995–96, 2004 and 2014). We described changes in self-rated health and family structure (number of children, sons, and daughters, and marital status) and, using ordinal regression modelling, determined the association between family structure and self-rated health, stratified by survey year and gender. Our results indicate that family structure changes that occurred between 1995-96 and 2014 were largely associated with better health. Though family sizes declined, there were no health gains from having more than two children. In fact, having many children (particularly daughters) was associated with worse health for both men and women. There was some evidence that being sonless or childless was associated with worse health, but it remained rare to not have a son or child. Being currently married was associated with better health and became more common over the inter-survey period. Although our results suggest that demographic trends have not adversely affected health of the older population thus far, we propose that the largest changes in family structure are yet to come. The support available in coming years (and potential health impact) will rely on flexibility of the current system

Gate Coupling to Nanoscale Electronics

The realization of single-molecule electronic devices, in which a nanometer-scale molecule is connected to macroscopic leads, requires the reproducible production of highly ordered nanoscale gaps in which a molecule of interest is electrostatically coupled to nearby gate electrodes. Understanding how the molecule-gate coupling depends on key parameters is crucial for the development of high-performance devices. Here we directly address this, presenting two- and three-dimensional finite-element electrostatic simulations of the electrode geometries formed using emerging fabrication techniques. We quantify the gate coupling intrinsic to these devices, exploring the roles of parameters believed to be relevant to such devices. These include the thickness and nature of the dielectric used, and the gate screening due to different device geometries. On the single-molecule (~1nm) scale, we find that device geometry plays a greater role in the gate coupling than the dielectric constant or the thickness of the insulator. Compared to the typical uniform nanogap electrode geometry envisioned, we find that non-uniform tapered electrodes yield a significant three orders of magnitude improvement in gate coupling. We also find that in the tapered geometry the polarizability of a molecular channel works to enhance the gate coupling

Factors in assessing effectiveness of orientation programs for public welfare caseworkers; a group project

A study done in 1968-1969 by students at Portland State University School of Social Work at the request of the Oregon State Public Welfare Commission Staff Development Division sought to devise an instrument for assessing the effectiveness of teaching the casework principles of Felix P. Biestek to casework trainees :in the public welfare\u27s orientation program. The test instrument developed was found to have low, but acceptable, internal reliability. Building en the previous year\u27s work, this 1969-1970 study sought to determine the validity of the test instrument by relating test scores to two measures of job performance, namely the latest supervisory civil service rating and a self-rating. Data was collected on thirty of the original test group. The test instrument was determined to be invalid on the basis of these assessments which used measures of total job performance as validating criteria. The study group concluded that the instrument should not be used by itself to determine the effectiveness of teaching casework principles to caseworkers in a public welfare orientation program. While the instrument was being tested, it was recognized that orientation training covers more than just Biestek’s casework principles. Other types of knowledge are also needed for caseworkers to perform effectively on their jobs. Consequently, the scope of the project was enlarged to include an exploration of other factors in caseworker development during orientation. To explore other factors, two instruments were used. One was a questionnaire developed by the group to obtain background information and to measure some attitudes of the caseworker toward his job and the welfare agency. The second was an instrument borrowed from the Oregon State Fish Commission for determining job satisfaction attitudes. The findings of the questionnaire indicated that informal training and supervision were important in caseworker development. The importance of supervision was reinforced by responses given to the survey of job satisfaction attitudes. The survey elicited complaints about bureaucratic agencies, i.e., the red tape, little use or trying of innovative methods, and poor communications within the agency and to the public. In view of the findings, the study group made six recommendations to the Oregon State Public Welfare Division regarding their orientation and staff development program. The study conclusions state that further research is needed (1) to define the casework job and then develop a test to measure a worker’s competency; (2) to develop tools to determine the social work attitudes, knowledge, and skills of the bachelor level service worker; and (3) to investigate use of the structured versus unstructured situation for teaching new caseworkers

Skeletal Muscle Lacking the Extreme C-Terminal SH3 Domain of Nebulin Exhibits Heightened Vulnerability to Eccentric Contraction-Induced Injury

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Musculoskeletal balance of the human wrist elucidated using intraoperative laser diffraction

Abstract This review describes a series of experiments in which sarcomere length was measured in human wrist muscles to understand their design. Sarcomere length measurements were combined with studies on cadaveric extremities to generate biomechanical models of human wrist function and to provide insights into the mechanism by which wrist strength balance is achieved. Intraoperative measurements of the human extensor carpi radialis brevis (ECRB) muscle during wrist joint rotation reveal that this muscle appears to be designed to operate on the descending limb of its length-tension curve and generates maximum tension with the wrist fully extended. Interestingly, the synergistic extensor carpi radialis longus (ECRL) also operates on its descending limb but over a much narrower sarcomere length range. This is due to the longer fibers and smaller wrist extension moment arm of the ECRL compared to the ECRB. Sarcomere lengths measured from wrist flexors are shorter compared to the extensors. Using a combination of intraoperative measurements on the flexor carpi ulnaris (FCU) and mechanical measurements of wrist muscles, joints and tendons, the general design of the prime wrist movers emerges: both muscle groups generate maximum force with the wrist fully extended. As the wrist flexes, force decreases due to extensor lengthening along the descending limb of their length-tension curve and flexor shortening along the ascending limb of their length-tension curve. The net result is a nearly constant ratio of flexor to extensor torque over the wrist range of motion and a wrist that is most stable in full extension. These experiments demonstrate the elegant match between muscle, tendon and joints acting at the wrist. Overall, the wrist torque motors appear to be designed for balance and control rather than maximum torque generating capacity