Coherency of synchronous generators

The linearized model of a synchronous generator, known in the literature as the Heffron-Phillips model, is extended to apply to a general power system with an arbitrary number of generators, and which takes into account network resistances. In this model a group of constants, called the M coefficients are developed which relate the torque, E(,q)(\u27\u27), and terminal voltage of each machine to the rotor angles and E(,q)(\u27\u27)\u27s of the various machines. In this investigation these constants are used to determine and analyze the coherency of synchronous generators;Using the M coefficients and generator parameters the system A matrix is formed. The coupling between the system inertial frequencies and the exciter frequencies is investigated using modal analysis. By partitioning the A matrix, two subsets, called the inertial matrix and the exciter matrix, are formed. The modal frequencies obtained from the partitioned matrices compare quite favorably with those obtained from the complete A matrix. This suggests decoupling the system\u27s inertial and exciter frequencies into independent groups;The Ml coefficients, a subset of the M coefficients, are contained in the inertial matrix. These coefficients are used to develop a technique for establishing inertial coherency that does not require time solutions or eigenvectors. It determines the tendency of coherent machines to swing together with a minimum amount of computation;Dynamic equivalents, formed when two generators are inertially coherent but with exciter modes and mode shapes that show no indication of coherency, are dealt with. A method of eliminating the proper exciter mode for the formation of an exciter equivalent is developed using the constraints of coherency. This provided a criterion by which other methods of exciter reduction can be judged. This modal reduction technique is advantageously incorporated into the more conventional exciter reduction method;The techniques developed in this research are applied to a 4-machine test system. The M coefficients and A matrices are calculated for a number of different cases. Inertial coherency is established and the improved method of exciter reduction is shown to be effective

The elements of filmmaking

Presents an educational multimedia development project created to teach novice learners about the various elements of the film making process. The multimedia web site designed for this project was created using Macromedia Flash 8. The process involved surveying people to determine learner needs and alpha and beta testing the final project to gather data regarding functionality and learner satisfaction

The Keck Cosmic Web Imager: a capable new integral field spectrograph for the W. M. Keck Observatory

The Keck Cosmic Web Imager (KCWI) is a new facility instrument being developed for the W. M. Keck Observatory and funded for construction by the Telescope System Instrumentation Program (TSIP) of the National Science Foundation (NSF). KCWI is a bench-mounted spectrograph for the Keck II right Nasmyth focal station, providing integral field spectroscopy over a seeing-limited field up to 20"x33" in extent. Selectable Volume Phase Holographic (VPH) gratings provide high efficiency and spectral resolution in the range of 1000 to 20000. The dual-beam design of KCWI passed a Preliminary Design Review in summer 2011. The detailed design of the KCWI blue channel (350 to 700 nm) is now nearly complete, with the red channel (530 to 1050 nm) planned for a phased implementation contingent upon additional funding. KCWI builds on the experience of the Caltech team in implementing the Cosmic Web Imager (CWI), in operation since 2009 at Palomar Observatory. KCWI adds considerable flexibility to the CWI design, and will take full advantage of the excellent seeing and dark sky above Mauna Kea with a selectable nod-and-shuffle observing mode. In this paper, models of the expected KCWI sensitivity and background subtraction capability are presented, along with a detailed description of the instrument design. The KCWI team is lead by Caltech (project management, design and implementation) in partnership with the University of California at Santa Cruz (camera optical and mechanical design) and the W. M. Keck Observatory (program oversight and observatory interfaces)

A genome-wide association study of anorexia nervosa suggests a risk locus implicated in dysregulated leptin signaling

J. Kaprio, A. Palotie, A. Raevuori-Helkamaa ja S. Ripatti ovat työryhmän Eating Disorders Working Group of the Psychiatric Genomics Consortium jäseniä. Erratum in: Sci Rep. 2017 Aug 21;7(1):8379, doi: 10.1038/s41598-017-06409-3We conducted a genome-wide association study (GWAS) of anorexia nervosa (AN) using a stringently defined phenotype. Analysis of phenotypic variability led to the identification of a specific genetic risk factor that approached genome-wide significance (rs929626 in EBF1 (Early B-Cell Factor 1); P = 2.04 x 10(-7); OR = 0.7; 95% confidence interval (CI) = 0.61-0.8) with independent replication (P = 0.04), suggesting a variant-mediated dysregulation of leptin signaling may play a role in AN. Multiple SNPs in LD with the variant support the nominal association. This demonstrates that although the clinical and etiologic heterogeneity of AN is universally recognized, further careful sub-typing of cases may provide more precise genomic signals. In this study, through a refinement of the phenotype spectrum of AN, we present a replicable GWAS signal that is nominally associated with AN, highlighting a potentially important candidate locus for further investigation.Peer reviewe

Associations between Attention-Deficit/Hyperactivity Disorder and various eating disorders: A Swedish nationwide population study using multiple genetically informative approaches

Background Although attention-deficit hyperactivity/impulsivity disorder (ADHD) and eating disorders (EDs) frequently co-occur, little is known about the shared etiology. In this study we comprehensively investigated the genetic association between ADHD and various EDs, including anorexia nervosa (AN) and other EDs (OED, including bulimia nervosa [BN]). Methods We applied different genetically informative designs to register-based information of a Swedish nationwide population (N=3,550,118). We first examined the familial co-aggregation of clinically diagnosed ADHD and EDs across multiple types of relatives. We then applied quantitative genetic modeling in full-sisters and maternal half-sisters to estimate the genetic correlations between ADHD and EDs. We further tested the associations between ADHD polygenic risk scores (PRS) and ED symptoms, and between AN PRS and ADHD symptoms, in a genotyped population-based sample (N=13,472). Results Increased risk of all types of EDs was found in individuals with ADHD (any ED: OR [95% CI]=3.97 [3.81-4.14], AN: 2.68 [2.15-2.86], OED: 4.66 [4.47-4.87], BN: 5.01 [4.63-5.41]) and their relatives compared to individuals without ADHD and their relatives. The magnitude of the associations reduced as the degree of relatedness decreased, suggesting shared familial liability between ADHD and EDs. Quantitative genetic models revealed stronger genetic correlation of ADHD with OED (0.37 [0.31-0.42]) than with AN (0.14 [0.05-0.22]). ADHD PRS correlated positively with ED symptom measures overall and sub-scales “drive for thinness” and “body dissatisfaction”, despite small effect sizes. Conclusions We observed stronger genetic association with ADHD for non-AN EDs than AN, highlighting specific genetic correlation beyond a general genetic factor across psychiatric disorders

Clozapine-induced agranulocytosis is associated with rare HLA-DQB1 and HLA-B alleles

Clozapine is a particularly effective antipsychotic medication but its use is curtailed by the risk of clozapine-induced agranulocytosis/granulocytopenia (CIAG), a severe adverse drug reaction occurring in up to 1% of treated individuals. Identifying genetic risk factors for CIAG could enable safer and more widespread use of clozapine. Here we perform the largest and most comprehensive genetic study of CIAG to date by interrogating 163 cases using genome-wide genotyping and whole-exome sequencing. We find that two loci in the major histocompatibility complex are independently associated with CIAG: a single amino acid in HLA-DQB1 (126Q) (P=4.7×10−14, odds ratio, OR=0.19, 95% CI 0.12–0.29) and an amino acid change in the extracellular binding pocket of HLA-B (158T) (P=6.4×10−10, OR=3.3, 95% CI 2.3–4.9). These associations dovetail with the roles of these genes in immunogenetic phenotypes and adverse drug responses for other medications, and provide insight into the pathophysiology of CIAG

‘A book is a book, all the world over’: New Zealand and the Colonial Writing World 1890–1945

The idea that literary expatriation was a prevalent and often necessary phenomenon for early twentieth-century Antipodean writers is well established, as it is widely believed that New Zealand and Australia were places not conducive to the nurturing of literary talent. In order to succeed, writers were forced to leave for places with developed publishing infrastructure and sympathetic communities of like-minded people like London, choosing expatriation over failure or mediocrity at home. This study, which is based on an empirical investigation into the lives and publication records of New Zealand authors, questions this long-held assumption by emphasising the transnational elements involved in literary production. New Zealand writers were able to remain in New Zealand and still be successful because of the existence of the ‘colonial writing world'—a system of cultural diffusion, literary networks and personal interactions that gave writers access to all the cultural capital of Britain (and other hubs of empire) through the lines of communication established by colonial expansion. The opportunities provided by international connections have been largely overlooked or dismissed until very recently because of the persistent nationalist framework within which New Zealand literary history has been written