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91.
Valiente-Dobón JJ Steinhardt T Svensson CE Afanasjev AV Ragnarsson I Andreoiu C Austin RA Carpenter MP Dashdorj D de Angelis G Dönau F Eberth J Farnea E Freeman SJ Gadea A Garrett PE Görgen A Grinyer GF Hyland B Jenkins D Johnston-Theasby F Joshi P Jungclaus A Lieb KP Macchiavelli AO Moore EF Mukherjee G Napoli DR Phillips AA Plettner C Reviol W Sarantites D Schnare H Schumaker MA Schwengner R Seweryniak D Smith MB Stefanescu I Thelen O Wadsworth R 《Physical review letters》2005,95(23):232501
Three rotational bands in 74Kr were studied up to (in one case one transition short of) the maximum spin I(max) of their respective single-particle configurations. Their lifetimes have been determined using the Doppler-shift attenuation method. The deduced transition quadrupole moments reveal a modest decrease, but far from a complete loss of collectivity at the maximum spin I(max). This feature, together with the results of mean field calculations, indicates that the observed bands do not terminate at I = I(max). 相似文献
92.
Hypericin in organic solvents displays two types of electronic spectra: one type which shows a distinct solvatochromic effect, the stable form, and the other, the unstable form, which lacks this property. The latter type is formed in dry nonprotic solvents (e.g. tetrahydrofuran, EtOAc) and can be converted to the stable form on addition of protic solvents. In order to establish the tautomeric structure of the unstable form we applied conventional nuclear magnetic resonance techniques as well as two-dimensional gradient-enhanced heteronuclear multiple-quantum correlation, gradient-enhanced ROESY and one-dimensional nuclear Overhauser effect difference experiments. All these techniques pointed to the fact that the unstable form has the 7,14-diketo tautomeric structure, like the stable form, and not the 1,6-diketo structure. Electronic spectroscopy indicated that the unstable form has acidic properties and therefore possesses two free OH groups at C3 and C4 at the bay region of the molecule. 相似文献
93.
Cho S Youn SJ Kim Y DiVenere A Wong GK Freeman AJ Ketterson JB 《Physical review letters》2001,87(12):126403
We have observed an epilayer-thickness-dependent polarity inversion for the growth of CdTe on Sb(Bi)/CdTe(111)B. For films with Sb(Bi) thicknesses of less than 40 A (15 A), the CdTe layer shows a B (Te-terminated) face, but it switches to an A (Cd-terminated) face for thicker layers. On the other hand, a CdTe layer grown on Bi(Sb)/CdTe(111)A always shows the A face regardless of Sb or Bi layer thicknesses. In order to address the observations we have performed ab initio calculations, which suggest that the polarity of a polar material on a nonpolar one results from the binding energy difference between the two possible surface configurations. 相似文献
94.
One Cubic Diophantine Inequality 总被引:1,自引:0,他引:1
Suppose that G(x) is a form, or homogeneous polynomial, of odddegree d in s variables, with real coefficients. Schmidt [15]has shown that there exists a positive integer s0(d), whichdepends only on the degree d, so that if s s0(d), then thereis an x Zs\{0} satisfying the inequality |G(x)|<1. (1) In other words, if there are enough variables, in terms of thedegree only, then there is a nontrivial solution to (1). Lets0(d) be the minimum integer with the above property. In thecourse of proving this important result, Schmidt did not explicitlygive upper bounds for s0(d). His methods do indicate how todo so, although not very efficiently. However, in fact muchearlier, Pitman [13] provided explicit bounds in the case whenG is a cubic. We consider a general cubic form F(x) with realcoefficients, in s variables, and look at the inequality |F(x)|<1. (2) Specifically, Pitman showed that if s(1314)2561, (3) then inequality (2) is non-trivially soluble in integers. Wepresent the following improvement of this bound. 相似文献
95.
Progress in direct-drive inertial confinement fusion research at the
laboratory for laser energetics
R. L. McCrory D. D. Meyerhofer S. J. Loucks S. Skupsky R. Betti T. R. Boehly T. J.B. Collins R. S. Craxton J. A. Delettrez D. H. Edgell R. Epstein K. A. Fletcher C. Freeman J. A. Frenje V. Yu. Glebov V. N. Goncharov D. R. Harding I. V. Igumenshchev R. L. Keck J. D. Kilkenny J. P. Knauer C. K. Li J. Marciante J. A. Marozas F. J. Marshall A. V. Maximov P. W. McKenty S. F.B. Morse J. Myatt S. Padalino R. D. Petrasso P. B. Radha S. P. Regan T. C. Sangster F. H. Séguin W. Seka V. A. Smalyuk J. M. Soures C. Stoeckl B. Yaakobi J. D. Zuegel 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(2):233-238
Direct-drive inertial confinement fusion (ICF) is
expected to demonstrate high gain on the National Ignition Facility (NIF) in
the next decade and is a leading candidate for inertial fusion energy
production. The demonstration of high areal densities in hydrodynamically
scaled cryogenic DT or D2 implosions with neutron yields that are a
significant fraction of the “clean” 1-D predictions will validate the
ignition-equivalent direct-drive target performance on the OMEGA laser at
the Laboratory for Laser Energetics (LLE). This paper highlights the
recent experimental and theoretical progress leading toward achieving this
validation in the next few years.
The NIF will initially be configured for X-ray drive and with no beams
placed at the target equator to provide a symmetric irradiation of a
direct-drive capsule. LLE is developing the “polar-direct-drive” (PDD)
approach that repoints beams toward the target equator. Initial 2-D
simulations have shown ignition. A unique “Saturn-like” plastic ring
around the equator refracts the laser light incident near the equator toward
the target, improving the drive uniformity.
LLE is currently constructing the multibeam, 2.6-kJ/beam, petawatt laser
system OMEGA EP. Integrated fast-ignition experiments, combining the OMEGA
EP and OMEGA Laser Systems, will begin in FY08. 相似文献
96.
Dave Wuchinich 《电子设计技术》2007,14(2):102-103
典型的压电传感器包含一片PZT-5A陶瓷材料的圆盘,在其表面有金属化电极.把导电环氧树脂涂到电极上,就可把外部导线连到传感器.绝缘粘合剂把组件连到待测结构,并把传感器和接地参考电位隔离开.圆盘面朝预期加速方向. 相似文献
97.
The Influence of Experience and Information Search Styles on Project Risk Identification Performance 总被引:1,自引:0,他引:1
Maytorena E. Winch G. M. Freeman J. Kiely T. 《Engineering Management, IEEE Transactions on》2007,54(2):315-326
The management of risks in projects is a growing area of concern. Both the identification and analysis phases of the risk management process are considered the most important, for they can have a big effect on the precision of the risk assessment exercise. Currently, it is assumed that project managers rely largely on experience to identify project risks. These decisions, influenced by individual perception and attitudes, are made primarily under conditions of uncertainty. Understanding how individuals respond to uncertain situations, therefore, requires an understanding of how individuals intuitively assess the situation they perceive, before expressing a response. The Project Risk Identification (Pro-RIde) project interviewed 51 project managers using active information search (AIS) as a data collection method and cognitive mapping as a data-capturing tool. Our results suggest that the role of experience in the risk identification process is much less significant than it is commonly assumed to be. By contrast, information search style, level of education and risk management training do play a significant role in risk identification performance. These findings suggest the potential for a more thorough approach to risk identification 相似文献
98.
Amjad Soomro Dave Cavalcanti 《Communications Magazine, IEEE》2007,45(2):114-122
The present view of medical environments, where isolated networks are used for IT and medical applications, is changing toward an integrated heterogeneous network scenario that can support a wide range of applications. WPAN and WLAN technologies play a fundamental role in enabling such integrated environment that is expected to support both medical and nonmedical applications. The ultimate goal is to exploit WPAN and WLAN technologies, as well as other wireless networks, such as 3G cellular systems and satellite networks, to support highly efficient medical care delivery, anytime and anywhere. However, the life-critical nature of some medical applications imposes additional challenges that have not been considered in nonmedical scenarios. This article discusses some future scenarios where WLAN and WPAN technologies can be used to provide an integrated and ubiquitous network in medical environments, and identifies the main issues to be addressed in order to meet the QoS requirements of different medical applications when operating in integrated environment 相似文献
99.
Background
Prior work from our group found that acid dissociation (pH 2.5 incubation) of serum from APP transgenic mice vaccinated against Aβ increased the apparent anti-Aβ titers, suggesting antibody masking by antigen in the ELISA assay. Subsequently, we found that pH 2.5 incubation of serum from unvaccinated non-transgenic mice showed antibody binding to Aβ1–42, but no increase when other proteins, including shorter Aβ peptides, coated the ELISA plate. To investigate further the effects of low pH incubation on apparent anti-Aβ1–42 signals, we examined normal sera from nonTg unvaccinated mice, nonTg mice vaccinated with Aβ peptide (to produce authentic anti-Aβ antibodies) or a monoclonal antibody against Aβ (6E10) using competitive-inhibition ELISA and Aβ epitope mapping assays. In addition, we examined use of a less stringent low pH procedure at pH 3.5, to ascertain if it had the same effects as the pH 2.5 procedure. 相似文献100.