1,341 research outputs found
Statistical Multifragmentation in Thermodynamic Limit
An exact analytical solution of the statistical multifragmentation model is
found in thermodynamic limit. The model exhibits a 1-st order phase transition
of the liquid-gas type. The mixed phase region of the phase diagram, where the
gas of nuclear fragments coexists with the infinite liquid condensate, is
unambiguously identified. The peculiar thermodynamic properties of the model
near the boundary between the mixed phase and the pure gaseous phase are
studied. The results for the caloric curve and specific heat are presented and
a physical picture of the nuclear liquid-gas phase transition is clarified.Comment: 4 figure
Specific heat at constant volume in the thermodynamic model
A thermodynamic model for multifragmentation which is frequently used appears
to give very different values for specific heat at constant volume depending
upon whether canonical or grand canonical ensemble is used. The cause for this
discrepancy is analysed.Comment: Revtex, 7 pages including 4 figure
RF and IF mixer optimum matching impedances extracted by large-signal vectorial measurements
This paper introduces a new technique that allows us to measure the admittance conversion matrix of a two-port device,using a Nonlinear Vector Network Analyzer.This method is applied to extract the conversion matrix of a 0.2 µµµµm pHEMT,driven by a 4.8 GHz pump signal,at different power levels,using an intermediate frequency of 600 MHz.The issue on data inconsistency due to phase randomization among different measurements is discussed and a proper pre- processing algorithm is proposed to fix the problem. The output of this work consists of a comprehensive experimental evaluation of up-and down-conversion maximum gain,stability,and optimal RF and IF impedances
Model of multifragmentation, Equation of State and phase transition
We consider a soluble model of multifragmentation which is similar in spirit
to many models which have been used to fit intermediate energy heavy ion
collision data. We draw a p-V diagram for the model and compare with a p-V
diagram obtained from a mean-field theory. We investigate the question of
chemical instability in the multifragmentation model. Phase transitions in the
model are discussed.Comment: Revtex, 9 pages including 6 figures: some change in the text and Fig.
Negative specific heat in a thermodynamic model of multifragmentation
We consider a soluble model of multifragmentation which is similar in spirit
to many models which have been used to fit intermediate energy heavy ion
collision data. In this model is always positive but for finite nuclei
can be negative for some temperatures and pressures. Furthermore,
negative values of can be obtained in canonical treatment. One does not
need to use the microcanonical ensemble. Negative values for can persist
for systems as large as 200 paticles but this depends upon parameters used in
the model calculation. As expected, negative specific heats are absent in the
thermodynamic limit.Comment: Revtex, 13 pages including 6 figure
Critical Exponents of the Statistical Multifragmentation Model
For the statistical multifragmentation model the critical indices
are calculated as functions of
the Fisher parameter . It is found that these indices have different
values than in Fisher's droplet model. Some peculiarities of the scaling
relations are discussed. The basic model predicts for the index a narrow
range of values, , which is consistent with two
experiments on nuclear multifragmentation.Comment: minor changes of the text, four references adde
Finite element analysis of three- and four-unit bridges
A two-dimensional finite element model of a mandibular quadrant was used to examine differences in magnitude of the principal stresses from the placement of three- and four-unit bridges. The area of interest spanned the first premolar to the second molar. Loading conditions were (i) vertical and distributed and (ii) 30° to the vertical and concentrated. The principal stresses were calculated and compared for: (i) the first molar removed with the remaining bone either cancellous or cancellous surrounded by a cortical shell; (ii) as in (i) but with the second premolar and first molar removed; (iii) a three-unit bridge spanning the second premolar to the second molar; and (iv) a four-unit bridge spanning the first premolar to the second molar. Each tooth was supported by periodontal ligaments, cortical and cancellous bone with each assigned the appropriate physical constants. Removal of the first molar resulted in considerable variation of the stresses especially when the cortical shell was replaced by cancellous bone. Because of the lower modulus of cancellous bone and its lower load-bearing capabilities the stresses were three to ten times lower and more uniform within the cancellous bone. Generally, the addition of a bridge resulted in lower and better distributed Σ min stresses. The bridge also resulted in higher tensile stresses distal to the abutment teeth which theoretically could result in bone deposition. No significant differences in magnitude were observed between the three- and four-unit bridge. From a stress standpoint the bridges resulted in more uniform stress distribution around the abutments and an increase in the tensile stresses distal to the abutments. Such findings support the placement of a fixed bridge to maintain bone in an edentulous area.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74974/1/j.1365-2842.1989.tb01384.x.pd
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Achieving Food Supply Chain Resilience during Natural Disasters through Industry 5.0 enablers - Empirical insights based on an FsQCA approach
YesThe purpose of this research is to establish the necessary and sufficient conditions for food safety and security during pandemic outbreaks, focusing on the case of COVID-19 to ensure resilience of the food supply chain. The study emphasises on the complexity theory of fuzzy set Qualitative Comparative Analysis (fsQCA), to establish a result-driven definition of Industry 5.0 (I5.0) during and post pandemics. The results of this study revealed that a combination of conditions derived from pandemic policy related reforms and I5.0 enablers will assist manufacturers and suppliers in establishing food safety and security during and post the COVID-19 era in a developing economy. Food safety and security being the goal, based on a survey of 140 food companies, this study provides insights to manufacturers and policymakers to enable selective implementation of I5.0 enabling technologies and pandemic policies
Multiple field inflation
Inflation offers a simple model for very early evolution of our Universe and
the origin of primordial perturbations on large scales. Over the last 25 years
we have become familiar with the predictions of single-field models, but
inflation with more than one light scalar field can alter preconceptions about
the inflationary dynamics and our predictions for the primordial perturbations.
I will discuss how future observational data could distinguish between
inflation driven by one field, or many fields. As an example, I briefly review
the curvaton as an alternative to the inflaton scenario for the origin of
structure.Comment: 27 pages, no figures. To appear in proceedings of 22nd IAP
Colloquium, Inflation +25, Paris, June 200
Gag-Protease Sequence Evolution Following Protease Inhibitor Monotherapy Treatment Failure in HIV-1 Viruses Circulating in East Africa.
Around 2.5 million HIV-infected individuals failing first-line therapy qualify for boosted protease inhibitor (bPI)-based second-line therapy globally. Major resistance mutations are rarely present at treatment failure in patients receiving bPI and the determinants of failure in these patients remain unknown. There is evidence that Gag can impact PI susceptibility. Here, we have sequenced Gag-Protease before and following failure in 23 patients in the SARA trial infected with subtypes A, C, and D viruses. Before bPI, significant variation in Protease and Gag was observed at positions previously associated with PI exposure and resistance including Gag mutations L449P, S451N, and L453P and Protease K20I and L63P. Following PI failure, previously described mutations in Protease and Gag were observed, including those at the cleavage sites such as R361K and P453L. However, the emergence of clear genetic determinants of therapy failure across patients was not observed. Larger Gag sequence datasets will be required to comprehensively identify mutational correlates of bPI failure across subtypes
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