High efficiency multi-junction solar cell design

Energy from the sun is the best option for electricity generation as it is abundantly available everywhere and sustainable source. Advance of Photovoltaic (PV) technology in recent years has made solar energy one of the practical alternative energy sources available in the energy market. In order to make the PV energy more affordable and cost effective, major focus of the research community and industry is improvement on power efficiency of PV systems. Early stage of solar panel manufacturing known as process technology plays a crucial role in achieving above limits. This paper presents a novel process technology for solar panel with 6 junctions

Resource variation in colorectal surgery; a national centre-level analysis.

BACKGROUND: Delivery of quality colorectal surgery requires adequate resources. We set out to assess the relationship between resources and outcomes in English colorectal units. METHODS: Data was extracted from the ACPGBI resource questionnaire to profile resources. This was correlated with Hospital Episode Statistics (HES) outcome data including 90-day mortality and readmissions. Patient satisfaction measures were extracted from the Cancer Experience Patient Survey (CEPS) and compared at unit level. Centres were divided by workload into low, middle, and top tertile. RESULTS: Completed questionnaires were received from 75 centres in England. Service resources were similar between low and top tertiles in access to CEPOD theatre, level 2 or 3 beds per 250,000 population or likelihood of having a dedicated colorectal ward. There was no difference in staffing levels per 250,000 unit of population. Each 10% increase in the proportion of cases attempted laparoscopically, was associated with reduced 90-day unplanned readmission (RR 0.94, 95% CI 0.91 to 0.97, p<0.001). The presence of a dedicated colorectal ward (RR 0.85, 95% CI 0.73 to 0.99, p =0.040) was also associated with a significant reduction in unplanned readmissions. There was no association between staffing or service factors and patient satisfaction. DISCUSSION AND CONCLUSIONS: Resource levels do not vary based on unit of population. There is benefit associated with increased use of laparoscopy and a dedicated surgical ward. Alternative measures to assess the relationship between resources and outcome, such as failure to rescue, should be explored in UK practice. This article is protected by copyright. All rights reserved

Development of microcontroller based over-current relay controls

This Project is about designing the controls of an Overcurrent relay using microcontroller. Relay is an electrical switch. Generally it operates on electromagnetic principle for switching action. Over current (OC) relay is a type of relay which performs its switching action based on an input current to it. When the input current exceeds a particular pick up value the relay operates. Microcontroller based relays are gaining popularity as these have no mechanical contacts. These can operate at very high speeds. Any kind of characteristics can be obtained by using these. In a typical microcontroller based relay there is a current transducer, a controller, current transformer and a circuit breaker. Microcontroller reads load current via CT, transducer and ADC. When current is above pickup it gives a signal to circuit breaker to trip. Microcontroller can be programmed to obtain IDMT characteristic

Earthworm management in tropical agroecosystems

An ethnological survey of knowledge of earthworms was carried out in four tropical countries (Mexico, Peru, India and Congo). A total of 202 farmers from 20 localities were interviewed to clarify their perception of soil fertility and its relationship to earthworm activity. Four additional farmers' meetings supported the results of these inquiries. In Peru and India, most of the farmers recognized a beneficial effect of earthworms, whereas in Congo and Mexico lack of knowledge predominated. In this last country, sampling was more intensive, covered three different ethnic groups and revealed an interesting inter-ethnic variability. In America, empirical knowledge and myths recognized an important role of earthworms in soil fertility. It is concluded that management practices focused on increasing earthworm populations will be accepted by local farmers. In some situations, however, an educational programme will be necessary. (Résumé d'auteur

Earthworm management in tropical agroecosystems

A worldwide survey of earthworms in the humid tropics revealed that 51 exotics and 151 native species are commonly found in tropical agroecosystems. On the basis of frequency records and climatic and edaphic ranges, 21 exotics and 27 native species have been selected as possible candidates for manipulation. A multivariate analysis separated these species into four groups : (i) native species with wide edaphic and medium climatic tolerances ; (ii) exotic species with wide climatic and edaphic tolerances ; (iii) native and exotic species with narrow edaphic tolerances but more resistant to climatic variations ; and (iv) native species with limited tolerance for climatic and edaphic variations. Regarding management, species of group (ii) seem to be the most adaptable, both at regional and local levels (multipurpose species) ; group (i) can be managed for specific climatic conditions whereas group (iii) should be managed in specific soil environments. Species of group (iv) may only be managed at a very local scale. (Résumé d'auteur

Superconducting and normal-state interlayer-exchange-coupling in La0.67_{0.67}Sr0.33_{0.33}MnO3{3}-YBa2_{2}Cu3_{3}O7−La_{7}-La_{0.67}SrSr_{0.33}MnO MnO{3}$ epitaxial trilayers

The issue of interlayer exchange coupling in magnetic multilayers with superconducting (SC) spacer is addressed in La$_{0.67}$Sr$_{0.33}$MnO$_{3}$ (LSMO) - YBa$_{2}$Cu$_{3}$O$_{7}$ (YBCO) - La$_{0.67}$Sr$_{0.33}$MnO$_{3}$ (LSMO) epitaxial trilayers through resistivity, ac-susceptibility and magnetization measurements. The ferromagnetic (FM) LSMO layers possessing in-plane magnetization suppress the critical temperature (T$_{c})$ of the c-axis oriented YBCO thin film spacer. The superconducting order, however, survives even in very thin layers (thickness d$_{Y} \sim$ 50 {\AA}, $\sim$ 4 unit cells) at T $<$ 25 K. A predominantly antiferromagnetic (AF) exchange coupling between the moments of the LSMO layers at fields $<$ 200 Oe is seen in the normal as well as the superconducting states of the YBCO spacer. The exchange energy J$_{1}$ ($\sim$ 0.08 erg/cm$^{2}$ at 150 K for d$_{Y}$ = 75 {\AA}) grows on cooling down to T$_{c}$, followed by truncation of this growth on entering the superconducting state. The coupling energy J$_{1}$ at a fixed temperature drops exponentially with the thickness of the YBCO layer. The temperature and d$_{Y}$ dependencies of this primarily non-oscillatory J$_{1}$ are consistent with the coupling theories for systems in which transport is controlled by tunneling. The truncation of the monotonic T dependence of J$_{1}$ below T$_{c}$ suggests inhibition of single electron tunneling across the CuO$_{2}$ planes as the in-plane gap parameter acquires a non-zero value.Comment: Accepted for publication in Phys. Rev.

First-principles investigation of spin polarized conductance in atomic carbon wire

We analyze spin-dependent energetics and conductance for one dimensional (1D) atomic carbon wires consisting of terminal magnetic (Co) and interior nonmagnetic (C) atoms sandwiched between gold electrodes, obtained employing first-principles gradient corrected density functional theory and Landauer's formalism for conductance. Wires containing an even number of interior carbon atoms are found to be acetylenic with sigma-pi bonding patterns, while cumulene structures are seen in wires containing odd number of interior carbon atoms, as a result of strong pi-conjugation. Ground states of carbon wires containing up to 13 C atoms are found to have anti-parallel spin configurations of the two terminal Co atoms, while the 14 C wire has a parallel Co spin configuration in the ground state. The stability of the anti-ferromagnetic state in the wires is ascribed to a super-exchange effect. For the cumulenic wires this effect is constant for all wire lengths. For the acetylenic wires, the super-exchange effect diminishes as the wire length increases, going to zero for the atomic wire containing 14 carbon atoms. Conductance calculations at the zero bias limit show spin-valve behavior, with the parallel Co spin configuration state giving higher conductance than the corresponding anti-parallel state, and a non-monotonic variation of conductance with the length of the wires for both spin configurations.Comment: revtex, 6 pages, 5 figure

DNA linkage based diagnosis of Wilson disease in asymptomatic siblings

Wilson disease (WD) is an autosomal recessive disorder caused by defects in ATP7B gene located in chromosome 13q14, and manifested as hepatolenticular degeneration as a result of accumulation of copper. No information on the mutation in the ATP7B gene and haplotypes using linked markers is available for WD patients in India. Hence, the present study was undetaken to identify, by a PCR-based molecular diagnostic test, presymptomatic siblings of WD affected individuals in families with multiple offspring. Methods: Genomic DNA was prepared from the peripheral blood of the patients, siblings and his/her first degree relatives. The repeat-markers flanking WD locus were amplified by PCR using fluorescent labeled primers. Amplified DNA fragments were analyzed by polyacrylamide gel electrophoresis in ABI 377 DNA sequencing system. Genotypes of the samples were determined using Genescan software. Haplotypes were determined based on segregation of the alleles in the families under study. Results: Among 15 WD affected families with multiple children, 4 cases were identified where younger siblings shared same genotype as the patient at all three markers analyzed. Further, eight different haplotypes were detected in the four patients. Interpretation & conclusion: The siblings of the WD patients carrying the same genotype at the markers linked to WD locus were presymptomatically diagnosed individuals. Presence of eight different haplotypes in the four patients suggested mutational heterogeneity at the WD locus. The test helps clinicians for therapeutic intervention in suspect WD cases by copper chelating agents prior to manifestation of overt clinical symptoms. Key words ATP7B - genotype - haplotype - microsatellite - Wilson disease (WD) is a genetic disorder, which manifests as hepatolenticular degeneration as a result of accumulation of copper in the brain, liver, kidney and cornea due to its deranged biliary excretion1. In 1912, a WD was described as a familial syndrome of progressive lenticular degeneration associated with cirrhosis of the liver2. The etiological role of copper in the pathogenesis of WD was recognized much late

Vitrification of a monatomic 2D simple liquid

A monatomic simple liquid in two dimensions, where atoms interact isotropically through the Lennard-Jones-Gauss potential [M. Engel and H.-R. Trebin, Phys. Rev. Lett. 98, 225505 (2007)], is vitrified by the use of a rapid cooling technique in a molecular dynamics simulation. Transformation to a crystalline state is investigated at various temperatures and the time-temperature-transformation (TTT) curve is determined. It is found that the transformation time to a crystalline state is the shortest at a temerature 14% below the melting temperature Tm and that at temperatures below Tv = 0.6 Tm the transformation time is much longer than the available CPU time. This indicates that a long-lived glassy state is realized for T < Tv.Comment: 5pages,5figures,accepted for publication in CEJ