398 research outputs found
Table 1. Quick reference data Symbol Parameter Conditions Min Typ Max Unit VDS drain-source voltage Tj = 25 °C
1. General description P-channel enhancement mode Field-Effect Transistor (FET) in a leadless ultra small DFN1010D-3 (SOT1215) Surface-Mounted Device (SMD) plastic package using Trench MOSFET technology. 2. Features and benefits • Trench MOSFET technology • Leadless ultra small and ultra thin SMD plastic package: 1.1 × 1.0 × 0.37 mm • Exposed drain pad for excellent thermal conduction • ElectroStatic Discharge (ESD) protection 1 kV HBM • Drain-source on-state resistance RDSon = 100 m
A laboratory based system for Laue micro x-ray diffraction
A laboratory diffraction system capable of illuminating individual grains in a polycrystalline matrix is described. Using a microfocus x-ray source equipped with a tungsten anode and prefigured monocapillary optic, a micro-x-ray diffraction system with a 10 mum beam was developed. The beam profile generated by the ellipsoidal capillary was determined using the"knife edge" approach. Measurement of the capillary performance, indicated a beam divergence of 14 mrad and a useable energy bandpass from 5.5 to 19 keV. Utilizing the polychromatic nature of the incident x-ray beam and application of the Laue indexing software package X-Ray Micro-Diffraction Analysis Software, the orientation and deviatoric strain of single grains in a polycrystalline material can be studied. To highlight the system potential the grain orientation and strain distribution of individual grains in a polycrystalline magnesium alloy (Mg 0.2 wt percent Nd) was mapped before and after tensile loading. A basal (0002) orientation was identified in the as-rolled annealed alloy; after tensile loading some grains were observed to undergo an orientation change of 30 degrees with respect to (0002). The applied uniaxial load was measured as an increase in the deviatoric tensile strain parallel to the load axis (37 References)
Comment on Viscous Stability of Relativistic Keplerian Accretion Disks
Recently Ghosh (1998) reported a new regime of instability in Keplerian
accretion disks which is caused by relativistic effects. This instability
appears in the gas pressure dominated region when all relativistic corrections
to the disk structure equations are taken into account. We show that he uses
the stability criterion in completely wrong way leading to inappropriate
conclusions. We perform a standard stability analysis to show that no unstable
region can be found when the relativistic disk is gas pressure dominated.Comment: 9 pages, 4 figures, uses aasms4.sty, submitted for ApJ Letter
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Achievable magnetic fields of super-ferric helical undulators for the ILC.
The magnetic fields on the beam axis of helical undulators for the proposed International Linear Collider (ILC) gamma-ray production were calculated for undulator periods of 10 mm and 12 mm. The calculation assumed the use of low-carbon steel for the magnetic poles and a beam chamber outer diameter of 6.3 mm. Using NbTi superconducting coils at 4.2 K, the on-axis field for a 10-mm-period undulator was 0.62 T at the critical current density. The field for a 12-mm undulator period was 0.95 T, which gives a K value of 1.06. The K value for an 11-mm undulator with Nb{sub 3}Sn superconducting coils was estimated to about 1.1
Global survey of the frequency of atrial fibrillation-associated stroke: embolic stroke of undetermined source global registry
Background and Purpose—Atrial fibrillation (AF) is increasingly recognized as the single most important cause of disabling ischemic stroke in the elderly. We undertook an international survey to characterize the frequency of AF-associated stroke, methods of AF detection, and patient features.
Methods—Consecutive patients hospitalized for ischemic stroke in 2013 to 2014 were surveyed from 19 stroke research centers in 19 different countries. Data were analyzed by global regions and World Bank income levels.
Results—Of 2144 patients with ischemic stroke, 590 (28%; 95% confidence interval, 25.6–29.5) had AF-associated stroke, with highest frequencies in North America (35%) and Europe (33%) and lowest in Latin America (17%). Most had a history of AF before stroke (15%) or newly detected AF on electrocardiography (10%); only 2% of patients with ischemic stroke had unsuspected AF detected by poststroke cardiac rhythm monitoring. The mean age and 30-day mortality rate of patients with AF-associated stroke (75 years; SD, 11.5 years; 10%; 95% confidence interval, 7.6–12.6, respectively) were substantially higher than those of patients without AF (64 years; SD, 15.58 years; 4%; 95% confidence interval, 3.3–5.4; P<0.001 for both comparisons). There was a strong positive correlation between the mean age and the frequency of AF (r=0.76; P=0.0002).
Conclusions—This cross-sectional global sample of patients with recent ischemic stroke shows a substantial frequency of AF-associated stroke throughout the world in proportion to the mean age of the stroke population. Most AF is identified by history or electrocardiography; the yield of conventional short-duration cardiac rhythm monitoring is relatively low. Patients with AF-associated stroke were typically elderly (>75 years old) and more often women
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On-Axis Brilliance and Power of In-Vacuum Undulators for the Advanced Photon Source.
A request for studying the spectral performance of in-vacuum undulators (IVUs) for the APS storage ring was recently put forward. In-vacuum undulators are prevalent at other synchrotron radiation facilities such as the ESRF and the Spring-8. However, they never made it into the arsenal of undulators at the APS because the brilliance tuning curves were sufficiently wide due to the fact that the undulator minimum gap could be set as low as 10.5 mm. For sector 3, which in the past used a narrow-gap vacuum chamber, the minimum undulator pole gap was allowed to be set as low as 8.5 mm, providing contiguous tuning curves between the first and third harmonic radiation for a 2.7-cm-period device. (Subsequently, the narrow-gap vacuum chamber was removed and replaced with a standard vacuum chamber, which allows a minimum gap of 10.5 mm.) For sector 4, which currently holds the only narrow-gap vacuum chamber at the APS, the minimum gap is 9.5 mm. In this sector, a permanent magnet hybrid undulator with SmCo magnets is used instead of NdFeB magnets because of their higher radiation resistance and their better protection against radiation-induced demagnetization of the magnets. In the realm of looking to the future, new concepts and technologies are being revisited. Most notable is the superconducting undulator (SCU) technology, which provides the ultimate highest magnetic field of any technology and design. The SCU program has been ongoing at the APS for several years and substantial progress has been made.3,4 However, the in-vacuum undulators may bridge some of the user demands, and it is therefore worthwhile revisiting their potential at the APS. In this work, the following were assumed or required: (1) the smallest in-vacuum beam-stay-clear gap is 5.0 mm, (2) a beam-liner of 2 x 0.060 mm, which increases the pole gap by the same amount, (3) both NdFeB and SmCo magnets shall be studied, even though SmCo magnets are the preferred choice for very small gaps, (4) compare the in-vacuum undulators with superconducting NbTi undulators with a wall thickness/space of 2 x 1.0 mm, and (5) all undulators will have an effective magnetic length of 2.4 m. Three short undulator period lengths were chosen somewhat arbitrary and studied. We will compare the performance of undulators with period lengths of 2.5 cm and 2.0 cm to one with a 1.6-cm period, which is the chosen period length of the first designed and tested short-length SCU for the APS. Additionally, we will make comparisons with the undulator A, which has a period length of 3.3 cm
An Empirical Study of Bots in Software Development -- Characteristics and Challenges from a Practitioner's Perspective
Software engineering bots - automated tools that handle tedious tasks - are
increasingly used by industrial and open source projects to improve developer
productivity. Current research in this area is held back by a lack of consensus
of what software engineering bots (DevBots) actually are, what characteristics
distinguish them from other tools, and what benefits and challenges are
associated with DevBot usage. In this paper we report on a mixed-method
empirical study of DevBot usage in industrial practice. We report on findings
from interviewing 21 and surveying a total of 111 developers. We identify three
different personas among DevBot users (focusing on autonomy, chat interfaces,
and "smartness"), each with different definitions of what a DevBot is, why
developers use them, and what they struggle with. We conclude that future
DevBot research should situate their work within our framework, to clearly
identify what type of bot the work targets, and what advantages practitioners
can expect. Further, we find that there currently is a lack of general purpose
"smart" bots that go beyond simple automation tools or chat interfaces. This is
problematic, as we have seen that such bots, if available, can have a
transformative effect on the projects that use them.Comment: To be published at the ACM Joint European Software Engineering
Conference and Symposium on the Foundations of Software Engineering
(ESEC/FSE
Ascertaining the notion of board accountability in Chinese listed companies
Accountability is a concept that has been frequently referred to in Anglo-American systems and in the OECD’s corporate governance documents, as well as in the English translations of corporate governance documents from non-English speaking jurisdictions. It is in the Anglo-American literature, in particular, where the word finds prominence. It has been suggested in China that accountability is one of the basic principles of corporate governance that needs to be consistently enforced. But does this mean that board accountability, as it has been provided for in the Anglo-American system, is actually an element of Chinese corporate governance? If not, should it be adopted? Or should China develop a concept that is more appropriately included as a critical part of its own particular corporate governance needs? The paper aims to address these matters in order to ascertain where Chinese corporate governance stands on accountability as far as the boards of large listed companies are concerned, and what it should do. We opine that while there are elements of accountability in Chinese corporate governance, it does not have the form of accountability embraced in Anglo-American systems. But, it is argued, as China moves from having a system totally based on administrative governance to one that is based more on economic governance the kind of approach that applies in Anglo-American jurisdictions is likely to become more relevant. Within a hybrid corporate governance system combining elements of both administrative and economic governance, we develop a unique “wenze system” with forms and characters of accountability that is likely to develop to address the needs of corporate governance in China and the fostering of its listed companies
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