5,805 research outputs found
Conceptual design and feasibility evaluation model of a 10 to the 8th power bit oligatomic mass memory. Volume 3: Operation manual
An operation manual is presented for the oligatomic mass memory feasibility model. It includes a brief description of the memory and exerciser units, a description of the controls and their functions, the operating procedures, the test points and adjustments, and the circuit diagram
Conceptual design and feasibility evaluation model of a 10 to the 8th power bit oligatomic mass memory. Volume 2: Feasibility evaluation model
The partially populated oligatomic mass memory feasibility model is described and evaluated. A system was desired to verify the feasibility of the oligatomic (mirror) memory approach as applicable to large scale solid state mass memories
Neutron-Star-Merger Equation of State
In this work, we discuss the dense matter equation of state (EOS) for the
extreme range of conditions encountered in neutron stars and their mergers. The
calculation of the properties of such an EOS involves modeling different
degrees of freedom (such as nuclei, nucleons, hyperons, and quarks), taking
into account different symmetries, and including finite density and temperature
effects in a thermodynamically consistent manner. We begin by addressing
subnuclear matter consisting of nucleons and a small admixture of light nuclei
in the context of the excluded volume approach. We then turn our attention to
supranuclear homogeneous matter as described by the Chiral Mean Field (CMF)
formalism. Finally, we present results from realistic neutron-star-merger
simulations performed using the CMF model that predict signatures for
deconfinement to quark matter in gravitational wave signals.Comment: Contribution to the Special Issue "Compact Stars in the QCD Phase
Diagram and in the Multi-Messenger Era of Astronomy" dedicated to the
conference: Compact Stars in the QCD Phase Diagram VI
The hidden X-ray breaks in afterglow light curves
Gamma-Ray Burst (GRB) afterglow observations in the Swift era have a
perceived lack of achromatic jet breaks compared to the BeppoSAX, or pre-Swift
era. Specifically, relatively few breaks, consistent with jet breaks, are
observed in the X-ray light curves of these bursts. If these breaks are truly
missing, it has serious consequences for the interpretation of GRB jet
collimation and energy requirements, and the use of GRBs as standard candles.
Here we address the issue of X-ray breaks which are possibly 'hidden' and
hence the light curves are misinterpreted as being single power-laws. We show
how a number of precedents, including GRB 990510 & GRB 060206, exist for such
hidden breaks and how, even with the well sampled light curves of the Swift
era, these breaks may be left misidentified. We do so by synthesising X-ray
light curves and finding general trends via Monte Carlo analysis. Furthermore,
in light of these simulations, we discuss how to best identify achromatic
breaks in afterglow light curves via multi-wavelength analysis.Comment: 4 pages, contributed talk, submitted to the proceedings of Gamma Ray
Bursts 2007, Santa Fe, New Mexico, November 5-9 200
Global existence of classical solutions to the Vlasov-Poisson system in a three dimensional, cosmological setting
The initial value problem for the Vlasov-Poisson system is by now well
understood in the case of an isolated system where, by definition, the
distribution function of the particles as well as the gravitational potential
vanish at spatial infinity. Here we start with homogeneous solutions, which
have a spatially constant, non-zero mass density and which describe the mass
distribution in a Newtonian model of the universe. These homogeneous states can
be constructed explicitly, and we consider deviations from such homogeneous
states, which then satisfy a modified version of the Vlasov-Poisson system. We
prove global existence and uniqueness of classical solutions to the
corresponding initial value problem for initial data which represent spatially
periodic deviations from homogeneous states.Comment: 23 pages, Latex, report #
Approach to equilibrium in adiabatically evolving potentials
For a potential function (in one dimension) which evolves from a specified
initial form to a different asymptotically, we study the
evolution, in an overdamped dynamics, of an initial probability density to its
final equilibeium.There can be unexpected effects that can arise from the time
dependence. We choose a time variation of the form
. For a , which is
double welled and a which is simple harmonic, we show that, in
particular, if the evolution is adiabatic, the results in a decrease in the
Kramers time characteristics of . Thus the time dependence makes
diffusion over a barrier more efficient. There can also be interesting
resonance effects when and are two harmonic potentials
displaced with respect to each other that arise from the coincidence of the
intrinsic time scale characterising the potential variation and the Kramers
time.Comment: This paper contains 5 page
Constant-time solution to the Global Optimization Problem using Bruschweiler's ensemble search algorithm
A constant-time solution of the continuous Global Optimization Problem (GOP)
is obtained by using an ensemble algorithm. We show that under certain
assumptions, the solution can be guaranteed by mapping the GOP onto a discrete
unsorted search problem, whereupon Bruschweiler's ensemble search algorithm is
applied. For adequate sensitivities of the measurement technique, the query
complexity of the ensemble search algorithm depends linearly on the size of the
function's domain. Advantages and limitations of an eventual NMR implementation
are discussed.Comment: 14 pages, 0 figure
Liver transplantation in primary biliary cirrhosis: Risk assessment and 11-year follow-up
Background/Aims: Liver transplantation (LTx) is the only established treatment in patients with end-stage primary biliary cirrhosis (PBC). Although short-term survival after LTx in this group of patients is usually good, few data exist on the long-term survival. The optimal timing of transplantation is difficult. Thus, the aims of this study were to assess the long-term survival of patients with PBC after LTx and to identify potential predictive factors for a positive outcome. Methods: Survival of 28 patients with PBC who underwent LTx between 1985 and July 1999 in a single center was studied by Kaplan-Meier analysis and was compared to predicted survival without LTx using established prognostic models for PBC, the Mayo and European risk scores. Potential prognostic parameters obtained before LTx were tested for correlation to survival. Rates of bone fractures as markers of hepatic osteodystrophy were compared before and after LTx. Results: Median follow-up after LTx was 90 months with a maximum of 140 months. Actuarial survival of patients with PBC was 89% after 1, 5, and 10 years and was significantly better than estimated survival without LTx after 1-7 years as calculated by the Mayo and European risk scores. Of several parameters tested, only serum bilirubin and the prognostic scores, but no other liver function tests obtained immediately prior to transplantation were significantly correlated with survival after LTx. The duration of intensive care after LTx was not associated with any parameters obtained before LTx. Bone fractures were diagnosed in 43% of patients of whom the vast majority were osteopenic before LTx as determined by osteodensitometry. Conclusion: Longterm survival of a well-defined group of patients with PBC was excellent after LTx and was inversely correlated with preoperative serum bilirubin levels as well as Mayo and European risk scores. Copyright (C) 2000 S. Karger AG. Basel
Pitfalls of lateral external fixation for supracondylar humeral fractures in children
Introduction: Closed reduction and percutaneous pinning is a standard treatment for dislocated supracondylar humeral fractures in children. However, the management of these fractures remains challenging. The aim of this study was to evaluate lateral external fixation as a treatment alternative for these fractures. Materials and methods: All supracondylar fractures treated with lateral external fixation between 2005 and 2007 were evaluated retrospectively. Long-term outcome was assessed with regards to carrying angle, malalignment, and motion. Results: Twenty-eight patients with Gartland type III fractures and one with a Y-type fracture were included in the study (mean age 6.5years). Cosmetic results were excellent in 88%, good in 8%, and fair in one patient. Functional results were excellent in 83%, good in 10%, and fair in 7%. However, 3 patients (10%) showed complete radial palsy postoperatively. In all of these patients, high insertion of the proximal pin (2.9-3.6cm above the fracture) was noted. On revision, one superficial lesion and one total transection of the nerve at the level of the proximal pin was detected. One patient showed no macroscopic damage. The transected nerve was reconstructed using an autograft, and all patients completely recovered within 2-6months. Conclusion: Lateral external fixation is an alternative method for the treatment of displaced or unstable supracondylar fractures in children, facilitating reduction and improving fracture stability. However, iatrogenic radial nerve injury is a risk, and we therefore strongly recommend inserting the proximal pin under direct vision within 2cm from the fracture line using a drill sleev
Additive utility in prospect theory
Prospect theory is currently the main descriptive theory of decision under uncertainty. It generalizes expected utility by introducing nonlinear decision weighting and loss aversion. A difficulty in the study of multiattribute utility under prospect theory is to determine when an attribute yields a gain or a loss. One possibility, adopted in the theoretical literature on multiattribute utility under prospect theory, is to assume that a decision maker determines whether the complete outcome is a gain or a loss. In this holistic evaluation, decision weighting and loss aversion are general and attribute-independent. Another possibility, more common in the empirical literature, is to assume that a decision maker has a reference point for each attribute. We give preference foundations for this attribute-specific evaluation where decision weighting and loss aversion are depending on the attributes
- …