995 research outputs found

    A Study to Determine the Necessary Content for an Educational Unit for Career Path Research

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    This study had three general research objectives: 1) to determine what information is currently provided the students through the existing efforts of admissions, program orientations, career search offices and current career development classes; 2) to determine the most valuable information for career planning to be included in an intensive unit of study; 3) to structure a unit of study to include the determined content for a currently existing Career Management course which would effect an increased satisfaction perception by the students

    Rapidly Solidified Rare-Earth Permanent Magnets: Processing, Properties, and Applications

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    Rapidly solidified rare-earth-based permanent magnets are considered to have better potential as permanent magnets compared to the conventional bulk materials, which can be attributed to their improved microstructure and better magnetic properties compared to rare-earth magnets synthesized by the conventional (powder metallurgy) routes. The performance (quality) of these magnets depends on the thermodynamics and kinetics of the different processing routes, such as atomization, melt spinning, and melt extraction. Here, we review the various processing routes of rapidly solidified rare-earth permanent magnets and the related properties and applications. In the review, some specific alloy systems, such as Sm–Co-based alloys, Nd–Fe–B, and interstitially modified Fe-rich rare-earth magnets are discussed in detail mentioning their processing routes and subsequently achieved crystal structure, microstructure and magnetic properties, and the related scopes for various applications. Some newly developed nanocomposites and thin-film magnets are also included in the discussion

    Rapidly Solidified Sm–Co–V Nanocomposite Permanent Magnets

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    Alloys around the Sm–Co eutectic composition provide an opportunity to form two-phase nanocomposite permanent magnets consisting of nanoscale Co fibers embedded in Sm2Co17.While ternary alloying elements may refine the scale of the structure, they may also disrupt the eutectic growth and lead to the formation of primary Co. Thus, microstructural selection maps were constructed for conventionally solidified Sm–Co–V alloys. It was found that V additions enlarged the primary Sm2Co17-forming region and, at (Sm0.09Co0.91)97 V3, resulted in a eutectic structure. Upon rapid solidification, this alloy was determined to have a coercivity of 5 kOe with a high remanent ratio. However, the V addition reduced the magnetization, which limited the energy product to 4.3 MG Oe. The rapidly solidified structure consisted of primary SmCo7 dendrites along with an intergranular Co region, suggesting that eutectic structure formation is skewed by underlying metastable phase relationships

    Rapidly Solidified Sm–Co–V Nanocomposite Permanent Magnets

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    Alloys around the Sm–Co eutectic composition provide an opportunity to form two-phase nanocomposite permanent magnets consisting of nanoscale Co fibers embedded in Sm2Co17.While ternary alloying elements may refine the scale of the structure, they may also disrupt the eutectic growth and lead to the formation of primary Co. Thus, microstructural selection maps were constructed for conventionally solidified Sm–Co–V alloys. It was found that V additions enlarged the primary Sm2Co17-forming region and, at (Sm0.09Co0.91)97 V3, resulted in a eutectic structure. Upon rapid solidification, this alloy was determined to have a coercivity of 5 kOe with a high remanent ratio. However, the V addition reduced the magnetization, which limited the energy product to 4.3 MG Oe. The rapidly solidified structure consisted of primary SmCo7 dendrites along with an intergranular Co region, suggesting that eutectic structure formation is skewed by underlying metastable phase relationships

    Hyperinsulinism-hyperammonaemia syndrome: novel mutations in the GLUD1 gene and genotype-phenotype correlations

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    Background: Activating mutations in the GLUD1 gene (which encodes for the intra-mitochondrial enzyme glutamate dehydrogenase, GDH) cause the hyperinsulinism–hyperammonaemia (HI/HA) syndrome. Patients present with HA and leucine-sensitive hypoglycaemia. GDH is regulated by another intra-mitochondrial enzyme sirtuin 4 (SIRT4). Sirt4 knockout mice demonstrate activation of GDH with increased amino acid-stimulated insulin secretion. Objectives: To study the genotype–phenotype correlations in patients with GLUD1 mutations. To report the phenotype and functional analysis of a novel mutation (P436L) in the GLUD1 gene associated with the absence of HA. Patients and methods: Twenty patients with HI from 16 families had mutational analysis of the GLUD1 gene in view of HA (n=19) or leucine sensitivity (n=1). Patients negative for a GLUD1 mutation had sequence analysis of the SIRT4 gene. Functional analysis of the novel P436L GLUD1 mutation was performed. Results: Heterozygous missense mutations were detected in 15 patients with HI/HA, 2 of which are novel (N410D and D451V). In addition, a patient with a normal serum ammonia concentration (21 µmol/l) was heterozygous for a novel missense mutation P436L. Functional analysis of this mutation confirms that it is associated with a loss of GTP inhibition. Seizure disorder was common (43%) in our cohort of patients with a GLUD1 mutation. No mutations in the SIRT4 gene were identified. Conclusion: Patients with HI due to mutations in the GLUD1 gene may have normal serum ammonia concentrations. Hence, GLUD1 mutational analysis may be indicated in patients with leucine sensitivity; even in the absence of HA. A high frequency of epilepsy (43%) was observed in our patients with GLUD1 mutations

    Behavior of Biaxially Loaded Slab-Column Connections with Shear Studs

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    Results are presented from four non-prestressed concrete slabcolumn connection subassemblies tested under simulated gravity and earthquake-type loading. Each specimen consisted of a largescale first-story interior slab-column connection reinforced with headed shear studs, loaded to a gravity-shear ratio of 50%, and subjected to biaxial lateral displacements. The slabs, which were nominally identical aside from the shear stud reinforcement design, had a flexural reinforcement ratio in the column strip, based on the effective depth, of 0.7%. Shear stud reinforcement in the test specimens varied in terms of amount and spacing, both between and within stud peripheral lines. All four specimens exhibited drift capacities significantly lower than shown by previous studies. Although the lateral strength of the specimens was governed by the flexural capacity of the slab, severe concrete degradation ultimately limited the drift capacity of the connections. Signs of punching-related damage were first observed during the cycle to 1.85% drift in each loading direction. Test results suggest that the minimum amount of shear reinforcement required in Section 21.13.6 of ACI 318-11 when neither a drift nor a combined shear-stress check is performed (vs ≥ 3.5√fc′, psi [0.29√fc′, MPa]) is adequate for connections subjected to a gravity shear ratio of up to 50% and resultant drifts from biaxial displacements of up to 2.0% if studs are spaced at less than 2d within the first two peripheral lines. For larger drift demands, a maximum stud spacing within the first three peripheral lines of 1.5d is recommended.Network for Earthquake Engineering Simulation (NEES) Program (Grant No. 0936519

    The Optical Alignment System of the ZEUS MicroVertex Detector

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    The laser alignment system of the ZEUS microvertex detector is described. The detector was installed in 2001 as part of an upgrade programme in preparation for the second phase of electron-proton physics at the HERA collider. The alignment system monitors the position of the vertex detector support structure with respect to the central tracking detector using semi-transparent amorphous-silicon sensors and diode lasers. The system is fully integrated into the general environmental monitoring of the ZEUS detector and data has been collected over a period of 5 years. The primary aim of defining periods of stability for track-based alignment has been achieved and the system is able to measure movements of the support structure to a precision around 10μ10 \mum.Comment: 38 pages; 17 figure

    External and internal noise surveys of London primary schools

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    Internal and external noise surveys have been carried out around schools in London, UK, to provide information on typical levels and sources to which children are exposed while at school. Noise levels were measured outside 142 schools, in areas away from flightpaths into major airports. 86% of the schools surveyed were exposed to noise from road traffic, the average external noise level outside a school being 57 dB LAeq. Detailed internal noise surveys have been carried out in 140 classrooms in 16 schools, together with classroom observations. It was found that noise levels inside classrooms depend upon the activities in which the children are engaged, with a difference of 20 dB LAeq between the 'quietest' and 'noisiest' activities. The average background noise level in classrooms exceeds the level recommended in current standards. The number of children in the classroom was found to affect noise levels. External noise influenced internal noise levels only when children were engaged in the quietest classroom activities. The effects of the age of the school buildings and types of window upon internal noise were examined but results were inconclusive

    Diazoxide-responsive hyperinsulinemic hypoglycemia caused by HNF4A gene mutations

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    Objective: The phenotype associated with heterozygous HNF4A gene mutations has recently been extended to include diazoxide responsive neonatal hypoglycemia in addition to maturity-onset diabetes of the young (MODY). To date, mutation screening has been limited to patients with a family history consistent with MODY. In this study, we investigated the prevalence of HNF4A mutations in a large cohort of patients with diazoxide responsive hyperinsulinemic hypoglycemia (HH). Subjects and methods: We sequenced the ABCC8, KCNJ11, GCK, GLUD1, and/or HNF4A genes in 220 patients with HH responsive to diazoxide. The order of genetic testing was dependent upon the clinical phenotype. Results: A genetic diagnosis was possible for 59/220 (27%) patients. KATP channel mutations were most common (15%) followed by GLUD1 mutations causing hyperinsulinism with hyperammonemia (5.9%), and HNF4A mutations (5%). Seven of the 11 probands with a heterozygous HNF4A mutation did not have a parent affected with diabetes, and four de novo mutations were confirmed. These patients were diagnosed with HI within the first week of life (median age 1 day), and they had increased birth weight (median +2.4 SDS). The duration of diazoxide treatment ranged from 3 months to ongoing at 8 years. Conclusions: In this large series, HNF4A mutations are the third most common cause of diazoxide responsive HH. We recommend that HNF4A sequencing is considered in all patients with diazoxide responsive HH diagnosed in the first week of life irrespective of a family history of diabetes, once KATP channel mutations have been excluded
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