1,944 research outputs found
Study of fault-tolerant software technology
Presented is an overview of the current state of the art of fault-tolerant software and an analysis of quantitative techniques and models developed to assess its impact. It examines research efforts as well as experience gained from commercial application of these techniques. The paper also addresses the computer architecture and design implications on hardware, operating systems and programming languages (including Ada) of using fault-tolerant software in real-time aerospace applications. It concludes that fault-tolerant software has progressed beyond the pure research state. The paper also finds that, although not perfectly matched, newer architectural and language capabilities provide many of the notations and functions needed to effectively and efficiently implement software fault-tolerance
Spectroscopy of 13B via the 13C(t,3He) reaction at 115 AMeV
Gamow-Teller and dipole transitions to final states in 13B were studied via
the 13C(t,3He) reaction at Et = 115 AMeV. Besides the strong Gamow-Teller
transition to the 13B ground state, a weaker Gamow-Teller transition to a state
at 3.6 MeV was found. This state was assigned a spin-parity of 3/2- by
comparison with shell-model calculations using the WBP and WBT interactions
which were modified to allow for mixing between nhw and (n+2)hw configurations.
This assignment agrees with a recent result from a lifetime measurement of
excited states in 13B. The shell-model calculations also explained the
relatively large spectroscopic strength measured for a low-lying 1/2+ state at
4.83 MeV in 13B. The cross sections for dipole transitions up to Ex(13B)= 20
MeV excited via the 13C(t,3He) reaction were also compared with the shell-model
calculations. The theoretical cross sections exceeded the data by a factor of
about 1.8, which might indicate that the dipole excitations are "quenched".
Uncertainties in the reaction calculations complicate that interpretation.Comment: 11 pages, 6 figure
Ponticulin plays a role in the positional stabilization of pseudopods
Ponticulin is a 17-kD glycoprotein that represents a major high affinity link between the plasma membrane and the cortical actin network of Dictyostelium. To assess the role of ponticulin in pseudopod extension and retraction, the motile behavior of two independently generated mutants lacking ponticulin was analyzed using computer-assisted two- and three-dimensional motion analysis systems. More than half of the lateral pseudopods formed off the substratum by ponticulin-minus cells slipped relative to the substratum during extension and retraction. In contrast, all pseudopods formed off the substratum by wild-type cells were positionally fixed in relation to the substratum. Ponticulin-minus cells also formed a greater proportion of both anterior and lateral pseudopods off the substratum and absorbed a greater proportion of lateral pseudopods into the uropod than wild-type cells. In a spatial gradient of cAMP, ponticulin-minus cells were less efficient in tracking the source of chemoattractant. Since ponticulin-minus cells extend and retract pseudopods with the same time course as wild-type cells, these behavioral defects in ponticulin-minus cells appear to be the consequence of pseudopod slippage. These results demonstrate that pseudopods formed off the substratum by wild-type cells are positionally fixed in relation to the substratum, that ponticulin is required for positional stabilization, and that the loss of ponticulin and the concomitant loss of positional stability of pseudopods correlate with a decrease in the efficiency of chemotaxis
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Offset of the electrical characteristics of alternating-current thin-film electroluminescent devices
Offset is observed in the charge–voltage (Q–V) or internal charge–phosphor field (Q–Fp) characteristics of certain alternating-current thin-film electroluminescent (ACTFEL) devices. This offset arises from a displacement along the voltage axis of a transient curve measured across a sense capacitor in the electrical characterization setup. A procedure for adjusting this offset is proposed that allows ACTFEL devices manifesting offset to be meaningfully analyzed. Two possible sources of offset are deduced from simulation and are associated with an asymmetry in the interface state energy depths at the two phosphor–insulator interfaces or with an asymmetry in the location of space charge generation in the phosphor
The Nd(He,) and Sm(,He) reactions with applications to decay of Nd
The Nd(He,) reaction at 140 MeV/u and Sm(,He)
reaction at 115 MeV/u were measured, populating excited states in Pm.
The transitions studied populate intermediate states of importance for the
(neutrinoless) decay of Nd to Sm. Monopole and
dipole contributions to the measured excitation-energy spectra were extracted
by using multipole decomposition analyses. The experimental results were
compared with theoretical calculations obtained within the framework of
Quasiparticle Random-Phase Approximation (QRPA), which is one of the main
methods employed for estimating the half-life of the neutrinoless
decay () of Nd. The present results thus provide useful
information on the neutrino responses for evaluating the and
matrix elements. The matrix element
calculated from the Gamow-Teller transitions through the lowest state
in the intermediate nucleus is maximally about half of that deduced from the
half-life measured in direct counting experiments and at least
several transitions through intermediate states in Pm are
required to explain the half-life.
Because Gamow-Teller transitions in the Sm(,He) experiment are
strongly Pauli-blocked, the extraction of Gamow-Teller strengths was
complicated by the excitation of the , ,
isovector spin-flip giant monopole resonance (IVSGMR). However, the near
absence of Gamow-Teller transition strength made it possible to cleanly
identify this resonance, and the strength observed is consistent with the full
exhaustion of the non-energy-weighted sum rule for the IVSGMR.Comment: 18 pages, 13 figures, 2 table
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Electroluminescence thermal quenching in SrS:Cu thin-film electroluminescent devices
Electroluminesence (EL) thermal quenching refers a reduction in luminance, concomitant with a reduction in transferred charge, when an alternating-current thin-film electroluminescent (ACTFEL) device is operated at an elevated temperature. EL thermal quenching is found to be significant in SrS:Cu ACTFEL devices operated above ~60-80 °C. Maximum transferred charge-maximum applied voltage (Qmax-Vmax) and transferred charge capacitance (i.e., dQmax /dVmax vs Vmax) measurements as a function of temperature in conjunction with ACTFEL device simulation are employed in order to establish that EL thermal quenching arises from a thermally activated annihilation of positive space charge and a corresponding increase in the threshold voltage
Evaluation of EGFR gene copy number as a predictive biomarker for the efficacy of cetuximab in combination with chemotherapy in the first-line treatment of recurrent and/or metastatic squamous cell carcinoma of the head and neck: EXTREME study
Background: The phase III EXTREME study demonstrated that combining cetuximab with platinum/5-fluorouracil (5-FU) significantly improved overall survival in the first-line treatment of patients with recurrent and/or metastatic squamous cell carcinoma of the head and neck (R/M SCCHN) compared with platinum/5-FU alone. The aim of this investigation was to evaluate elevated tumor EGFR gene copy number as a predictive biomarker in EXTREME study patients
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