1,321 research outputs found

    Managing Engineering Talent: Unique Challenges to Optimize the Best and Brightest

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    Most engineers are bright, hard-working, reliable, and prefer to avoid conflict. An engineering curriculum tends to self-select these characteristics. By most standards, you would expect workers exhibiting these traits to require minimal supervision. But is this true? Is this how most current engineering managers lead? Looking at some current theories on leadership combined with personal anecdotes, this presentation will look at some common misconceptions about leading engineers

    Voltage Stability Analysis of Grid-Connected Wind Farms with FACTS: Static and Dynamic Analysis

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    Recently, analysis of some major blackouts and failures of power system shows that voltage instability problem has been one of the main reasons of these disturbances and networks collapse. In this paper, a systematic approach to voltage stability analysis using various techniques for the IEEE 14-bus case study, is presented. Static analysis is used to analyze the voltage stability of the system under study, whilst the dynamic analysis is used to evaluate the performance of compensators. The static techniques used are Power Flow, V–P curve analysis, and Q–V modal analysis. In this study, Flexible Alternating Current Transmission system (FACTS) devices- namely, Static Synchronous Compensators (STATCOMs) and Static Var Compensators (SVCs) - are used as reactive power compensators, taking into account maintaining the violated voltage magnitudes of the weak buses within the acceptable limits defined in ANSI C84.1. Simulation results validate that both the STATCOMs and the SVCs can be effectively used to enhance the static voltage stability and increasing network loadability margin. Additionally, based on the dynamic analysis results, it has been shown that STATCOMs have superior performance, in dynamic voltage stability enhancement, compared to SVCs

    Viewpoint Stroke prevention in recent guidelines for the management of patients with atrial fibrillation: An appraisal.

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    Formal guidelines play an important role in disseminating the best available evidence knowledge and are expected to provide simple and practical recommendations for the most optimal management of patients with various conditions. Such guidelines have important implications for many disease states, which thereby could be more professionally managed in everyday clinical practice by clinicians with divergent educational backgrounds, and also more easily implemented in wards or outpatient clinics eliminating inequalities in health care management. In this brief Viewpoint, we provide an appraisal on the recommendations pertinent to the prevention of atrial fibrillation-related stroke or systemic thromboembolism, as provided in recently published guidelines for the management of this arrhythmia

    Mortality of federally endangered fishes induced by artificial breaching of the Santa Clara River lagoon, Ventura County, southern California

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    Fishes of southern California coastal streams and associated coastal lagoons live with a Mediterranean-style hydrological cycle. Winter rains open the lagoons to the ocean; subsequent dry season low flows and changes in sandy beach dynamics closes them for most of the year. Artificial breaching of barrier sand berms can disrupt fish populations and cause mortality. Such breaches have been rarely observed and then only after some time has passed. An artificial breaching at the mouth of the Santa Clara River, Ventura County, CA coincided with an extreme low tide on 17 September 2010. We observed the mortality of thousands of both native and non-native fishes and invasive frogs; including at least thousands of the federally endangered Tidewater Goby (Eucyclogobius newberryi) and seven smolts of the federally endangered southern Steelhead (Oncorhynchus mykiss). Despite the many anthropogenic, faunal, and non-faunally related reasons for breaching, our observations confirm such actions can be detrimental to conservation and recovery of threatened and endangered species as well as to other fauna and flora dependent on such habitats

    Tourmaline-quartz-cassiterite mineralization of the Land's End Granite at Nanjizal, west Cornwall

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    Nanjizal is one of the few locations in the southern segment of the Land's End Granite (Early Permian) where magmatic-hydrothermal tin mineralization has been worked. Three principal mineralization episodes are recognized. The first episode comprises steeply dipping ENE-WSW striking tourmaline quartz veins precipitated from magmatic-hydrothermal fluids during regional NNW-SSE extension; they are not associated with metalliferous mineralization. The second episode is represented by two sets of vertical/subvertical tourmaline veins striking, respectively, 280degrees and 340degrees. The NNW striking set hosts tourmaline-quartz-cassiterite ( alkali feldspar, apatite, zircon) mineralization and was worked for tin during the 19(th) Century. The first generation of tourmaline in these veins is dominated by the Mg-rich end-member, dravite. The subsequent two generations of tourmaline are dominated by the Ferich end-member, schorl, together with zoned cassiterite with Fe-rich cores and Fe-poor rims. The NNW striking tourmaline-quartz-cassiterite veins at Nanjizal have a similar orientation to cassiterite-bearing veins within the St. just Mining District further north. It is possible that the mineralization at Nanjizal was contemporaneous with mineralization in the St. Just Mining District and hence related to a later magmatic episode and the renewed release of magmatic-hydrothermal fluids during ENE-WSW extension. The third mineralization episode is dominated by steeply dipping WNW-NNW striking quartz-limonite-chalcedonyveins that are associated with wall rock hematisation and kaolinisation. Schorl-quartz-cassiterite mineralisation is relatively uncommon in S.W. England but there are remarkable similarities between the vein parageneses at Nanjizal and the Birch Tor-Vitifer area of Dartmoor; both are likely to have been sourced from predominantly magmatic-hydrothermal fluids

    Expansion of the non-native Mississippi Silverside, Menidia audens (Pisces, Atherinopsidae), into fresh and marine waters of coastal southern California

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    Abstract--Mississippi Silversides, Menidia audens, were first recorded in southern California reservoirs and nearby outflows in the late 1980s and early 1990s. In 1997-2000 they were taken in King Harbor, Redondo Beach,and in 2000 in the Santa Ana River. By 2005-2006 they were found in several other coastal drainages from the San Gabriel River in Orange and Los Angeles counties northward to Arroyo Burro, Santa Barbara County. Initial invasion was via the California Aqueduct in the late 1980s and early 1990s and more recently dispersal has taken place along the southern California coast. The records from King Harbor occurred for a relatively short period, mid-1997-mid-2000 (mostly 1997 and 1998) before they were established in coastal drainages. Their impact on native species is not known but on some occasions Mississippi Silversides have outnumbered native Topsmelt, Atherinops affinis, in small coastal lagoons estuaries. Mississippi Silversides are known to prey on eggs and larvae of other fishes and could be increasing predation on small native animals as well as serving as prey for larger piscivores like steelhead and terns.

    Draft Genome Sequence of Pseudoalteromonas sp. Strain JC3

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    We report the draft genome sequence for Pseudoalteromonas sp. strain JC3, an isolate obtained from an aquaculture facility for whiteleg shrimp (Litopenaeus vannamei). The JC3 genome suggests multiple mechanisms for microbial interactions, including a type VI secretion system and potential for antibiotic production

    The RACE to the EAST. In pursuit of rhythm control therapy for atrial fibrillation-a dedication to Harry Crijns

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    The RACE trial was one of the first landmark trials to establish whether restoring and maintaining sinus rhythm could reduce morbidity and mortality in patients with atrial fibrillation (AF). Its neutral outcome shaped clinical decision-making for almost 20 years. However, there were two important treatment-related factors associated with mortality of rhythm control therapy at that time: One was safety of antiarrhythmic drug therapy, and the other one withdrawal of anticoagulation after restoration of sinus rhythm. Both concerns have been overcome, and, moreover, important knowledge considering the importance of time for the treatment of AF has been gained. These insights led to the concept of the EAST-AFNET 4 trial, and after more than two decades in the pursuit of ongoing therapeutic improvement, early rhythm control therapy has demonstrated to reduce a composite of cardiovascular death, stroke, and hospitalization for worsening of HF or acute coronary syndrome, by 21% (first primary outcome, absolute reduction 1.1 per 100 patient-years). For this entire period, Harry Crijns characterized the treatment of AF patients, and contributed decisively to realizing the benefit of rhythm control therapy. It is almost easier to list the clinical trials without Harry's involvement than to list those which he co-designed and led

    Temporal trends of cause-specific mortality after diagnosis of atrial fibrillation.

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    BACKGROUND AND AIMS: Reports of outcomes after atrial fibrillation (AF) diagnosis are conflicting. The aim of this study was to investigate mortality and hospitalisation rates following AF diagnosis over time, by cause, and by patient features. METHODS: Individuals aged ≥16 years with a first diagnosis of AF were identified from the UK Clinical Practice Research Datalink-GOLD dataset from Jan 1, 2001 to Dec 31, 2017. The primary outcomes were all-cause and cause-specific mortality and hospitalisation at 1 year following diagnosis. Poisson regression was used to calculate rate ratios (RRs) for mortality and incidence rate ratios (IRRs) for hospitalisation and 95% confidence intervals (CIs) comparing 2001/02 and 2016/17, adjusted for age, sex, region, socioeconomic status and 18 major comorbidities. RESULTS: Of 72 412 participants, mean (SD) age was 75.6 (12.4) years and 44 762 (61.8%) had ≥3 comorbidities. All-cause mortality declined (RR 2016/17 vs 2001/02 0.72; 95% CI 0.65-0.80), with large declines for cardiovascular (RR 0.46; 95% CI 0.37-0.58) and cerebrovascular mortality (RR 0.41; 95% CI 0.29-0.60) but not for non-cardio/cerebrovascular causes of death (RR 0.91; 95% CI 0.80-1.04). By 2016/17 deaths from dementia (67, 8.0%), outstripped deaths from acute myocardial infarction, heart failure and acute stroke combined (56, 6.7%, p < 0.001). Overall hospitalisation rates increased (IRR 2016/17 vs 2001/02 1.17; 95% CI, 1.13-1.22), especially for non-cardio/cerebrovascular causes (IRR 1.42; 95% CI 1.39-1.45). Older, more deprived, and hospital-diagnosed AF patients experienced higher event rates. CONCLUSIONS: After AF diagnosis, cardio/cerebrovascular mortality and hospitalisation has declined, whilst hospitalisation for non-cardio/cerebrovascular disease has increased
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