Classical limit of the Nelson model

Since the development of quantum mechanics it has been natural to analyze the connection between classical and quantum mechanical descriptions of physical systems. In particular one should expect that in some sense when quantum mechanical effects becomes negligible the system will behave like it is dictated by classical mechanics. One famous relation between classical and quantum theory is due to Ehrenfest. This result was later developed and put on firm mathematical foundations by Hepp. He proved that matrix elements of bounded functions of quantum observables between suitable coherents states (that depend on Planck's constant h) converge to classical values evolving according to the expected classical equations when h goes to zero. His results were later generalized by Ginibre and Velo to bosonic systems with infinite degrees of freedom and scattering theory. In this thesis we study the classical limit of Nelson model, that describes non relativistic particles, whose evolution is dictated by Schrödinger equation, interacting with a scalar relativistic field, whose evolution is dictated by Klein-Gordon equation, by means of a Yukawa-type potential. The classical limit is a mean field and weak coupling limit. We proved that the transition amplitude of a creation or annihilation operator, between suitable coherent states, converges in the classical limit to the solution of the system of differential equations that describes the classical evolution of the theory. The quantum evolution operator converges to the evolution operator of fluctuations around the classical solution. Transition amplitudes of normal ordered products of creation and annihilation operators between coherent states converge to suitable products of the classical solutions. Transition amplitudes of normal ordered products of creation and annihilation operators between fixed particle states converge to an average of products of classical solutions, corresponding to different initial conditions.

The Effects of Interstate Speed Limit Increases: Fatality Rates and Traffic Diversion Versus Speed Spillover

This thesis examines two panel data sets of 48 states from 1981 to 2009 and utilizes ordinary least squares (OLS) and fixed effects models to explore the relationship between rural Interstate speed limits and fatality rates and whether rural Interstate speed limits affect non-Interstate safety. Models provide evidence that rural Interstate speed limits higher than 55 MPH lead to higher fatality rates on rural Interstates though this effect is somewhat tempered by reductions in fatality rates for roads other than rural Interstates. These results provide some but not unanimous support for the traffic diversion hypothesis that rural Interstate speed limit increases lead to decreases in fatality rates of other roads. To the author’s knowledge, this paper is the first econometric study to differentiate between the effects of 70 MPH speed limits and speed limits above 70 MPH on fatality rates using a multi-state data set. Considering both rural Interstates and other roads, rural Interstate speed limit increases above 55 MPH are responsible for 39,700 net fatalities, 4.1 percent of total fatalities from 1987, the year limits were first raised, to 2009.

Search for pair-produced massive coloured scalars in four-jet final states with the ATLAS detector in proton-proton collisions at sqrts=7 TeV

A search for pair-produced massive coloured scalar particles decaying to a four-jet final state is performed by the ATLAS experiment at the LHC in proton-proton collisions at root s = 7 TeV. The analysed data sample corresponds to an integrated luminosity of 4.6 fb(-1). No deviation from the Standard Model is observed in the invariant mass spectrum of the two-jet pairs. A limit on the scalar gluon pair production cross section of 70 pb (10 pb) is obtained at the 95 % confidence level for a scalar gluon mass of 150 GeV (350 GeV). Interpreting these results as mass limits on scalar gluons, masses ranging from 150 GeV to 287 GeV are excluded at the 95 % confidence level.

Search for Quantum Black Hole Production in High-Invariant-Mass Lepton plus Jet Final States Using pp Collisions at root s=8 TeV and the ATLAS Detector

This Letter presents a search for quantum black-hole production using 20.3 fb(-1) of data collected with the ATLAS detector in pp collisions at the LHC at root s = 8 TeV. The quantum black holes are assumed to decay into a final state characterized by a lepton (electron or muon) and a jet. In either channel, no event with a lepton-jet invariant mass of 3.5 TeV or more is observed, consistent with the expected background. Limits are set on the product of cross sections and branching fractions for the lepton + jet final states of quantum black holes produced in a search region for invariant masses above 1 TeV. The combined 95% confidence level upper limit on this product for quantum black holes with threshold mass above 3.5 TeV is 0.18 fb. This limit constrains the threshold quantum black-hole mass to be above 5.3 TeV in the model considered.

Search for squarks and gluinos with the ATLAS detector in final states with jets and missing transverse momentum using √s=8 TeV proton--proton collision data

A search for squarks and gluinos in final states containing high-pT jets, missing transverse momentum and no electrons or muons is presented. The data were recorded in 2012 by the ATLAS experiment in √s = 8TeV proton-proton collisions at the Large Hadron Collider, with a total integrated luminosity of 20.3 fb−1. Results are interpreted in a variety of simplified and specific supersymmetry-breaking models assuming that R-parity is conserved and that the lightest neutralino is the lightest supersymmetric particle. An exclusion limit at the 95% confidence level on the mass of the gluino is set at 1330GeV for a simplified model incorporating only a gluino and the lightest neutralino. For a simplified model involving the strong production of first- and second-generation squarks, squark masses below 850GeV (440GeV) are excluded for a massless lightest neutralino, assuming mass degenerate (single light-flavour) squarks. In mSUGRA/CMSSM models with tan β = 30, A0 = −2m0 and μ > 0, squarks and gluinos of equal mass are excluded for masses below 1700GeV. Additional limits are set for non-universal Higgs mass models with gaugino mediation and for simplified models involving the pair production of gluinos, each decaying to a top squark and a top quark, with the top squark decaying to a charm quark and a neutralino. These limits extend the region of supersymmetric parameter space excluded by previous searches with the ATLAS detector.

Implications of Longterm Diameter-Limit Harvesting: Effects on Radial Growth of Red Spruce (Picea rubens) and Genetic Diversity of White Pine (Pinus strobus)

For over 3 centuries, diameter-limit harvesting has been a predominant logging method in the northeastern United States. Silvicultural theory asserts that such intensively selective harvesting can lead to genetic degradation. A decrease in softwood productivity has recently been reported in Maine - has a long history of dysgenic selection degraded the genetic resources of Maine softwoods, contributing to a decrease in growth and productivity? This study examines two aspects of potential implications of diameter-limit harvesting: effects on residual phenotypes of red spruce and impacts on genetic diversity of white pine. Radial growth of residual red spruce trees in stands experiencing 50 years of fixed diameter-limit harvesting was measured using annual increment rings and compared with residual red spruce trees in positive selection stands. Trees remaiaing after several rounds of diameter-limit harvesting exhibited sigdicantl y smaller radial sizes throughout their lives, and displayed significantly slower growth rates for the first 80 years of measured growth. These results strongly suggest that the largest and fastest-growing genotypes and their respective gene complexes determining good radial growth have been removed from the diameter-limit stand. Dysgenic selection can be observed in fixed diarneter-limit stands, resulting in a diminished genetic resource and decreased residual stand value. To examine more direct genetic implications of long-term diameter-limit harvesting, microsatellite DNA markers were implemented to study genetic diversity of eastern white pine in Maine. Three age groups of trees were studied: mature trees older than 200 years, juvenile trees 5-30 years old, and embryos. Trees were genotyped at 10 microsatellite loci. Overall genetic diversity levels of eastern white pine in Maine were extremely high, with an average observed heterozygosity of 0.762. Genetic differentiation was minimal among and between all three age groups, although an excess of heterozygotes was shown in the mature and juvenile groups that was not reflected in the embryo group, which actually had a slight heterozygote deficiency. Allele frequencies did not differ significantly between age groups, but did reveal more rare and low frequency alleles in the embryo groups than in the mature group. Overall, low frequency alleles comprise the largest portion of alleles in the sample population, with no common alleles evident overall. These results suggest that significant genetic degradation has either not occurred for white pine, or that the results of dysgenic selection have not yet emerged. It is clear, however, that selective harvesting could result in a loss of low frequency alleles, which are a primary reserve of evolutionary potential in a species. Implications of these studies affect industrial forestry, regional economics, and ecological concerns for the northeast. Long-term diameter-limit harvesting can lead to a degradation of residual phenotypes, and an overall decrease in stand quality. Potentially, a loss of low frequency, locally adapted alleles could result in a decrease of allelic richness and degradation of the regidnal genetic resource. Decreased genetic variation can lead to seriously limited evolutionary potential of species and ecosystems, particularly in rapidly changing environments. Based on these findings, I recommend a reassessment of any harvesting prescription that includes fixed diameter-limit removals, particularly for species that have low natural genetic diversity levels or a limited natural range, such as red spruce. Maintenance of a healthy genetic reserve can avoid effects of dysgenic harvesting.

The medical malpractice insurance "crises" and federal medical malpractice tort reform: Collection and analysis of bills passed by the United States House of Representatives from 1995--2005

There have been three medical malpractice insurance "crises" in the United States over a time spanning roughly the past three decades (Poisson, 2004, p. 759-760). Each crisis is characterized by a number of common features, including rapidly increasing medical malpractice insurance premiums, cancellation of existing insurance policies, and a decreased willingness of insurers to offer or renew medical malpractice insurance policies (Poisson, 2004, p. 759-760). Given the recurrent "crises," many sources argue that medical malpractice insurance coverage has become too expensive a commodity—one that many physicians simply cannot afford (U.S. Department of Health and Human Services [HHS], 2002, p. 1-2; Physician Insurers Association of America [PIAA], 2003, p. 1; Jackiw, 2004, p. 506; Glassman, 2004, p. 417; Padget, 2003, p. 216). ^ The prohibitively high cost of medical liability insurance is said to limit the geographical areas and medical specializations in which physicians are willing to practice. As a result, the high costs of medical liability insurance are ultimately said to affect whether or not people have access to health care services. ^ In an effort to control the medical liability insurance crises—and to preserve or restore peoples' access to health care—every state in the United States has passed "at least some laws designed to reduce medical malpractice premium rates" (GAO, 2003, p.5-6). More recently, however, the United States has witnessed a push to implement federal reform of the medical malpractice tort system. Accordingly, this project focuses on federal medical malpractice tort reform. This project was designed to investigate the following specific question: Do the federal medical malpractice tort reform bills which passed in the House of Representatives between 1995 and 2005 differ in respect to their principle features? To answer this question, the text of the bills, law review articles, and reports from government and private agencies were analyzed. Further, a matrix was compiled to concisely summarize the principle features of the proposed federal medical malpractice tort reform bills. Insight gleaned from this investigation and matrix compilation informs discussion about the potential ramifications of enacting federal medical malpractice tort reform legislation. ^

Review of the Economic Development in the Western Balkan States. OSW STUDIES No. 19, 2005-08-10

Foreword. Ten years after the end of the armed conflict, the Western Balkans1 are still being considered as the “land of the unsuccessful policies”. Enormous financial and technical assistance transferred by the International Community has not managed to meet the goals of integrating the region within itself as well as within the European markets. Explanation for this can be found in the consequences of the war and the remnants of the socialist state. The complexity of current institutional/ political arrangements combined with the limited willingness of the regional actors to introduce and implement much of the needed reforms have additionally contributed to the current state of affairs. The economy and politics in the region intertwine to an extent as probably in none of the other post-communist states. Therefore, the paper presents the recent economic performance of the Western Balkan countries in the light of their limited institutional development and lack of efficient regional cooperation. The paper discusses the importance of foreign direct investments’ inflow for the economic growth of the “latecomer” states and presents major drawbacks which limit the influx of the foreign capital to the region. It presents private sector activity and regional cooperation programmes. It discusses the role of the International Community with the main focus on the activities of the European Union. The EU is examined not only as the main aid donor but more importantly as a foreign trade partner. Furthermore, it analyses the impact of the presence of the International Community and their strategies towards the region with the special attention to the EU. Finally, it presents recommendations for the improvement of the economic performance in light of the enhanced political cooperation between the EU and the region.

Define and limit the jurisdiction of courts sitting in equity ... : report [to accompany H. R. 5315].

Submitted by Mr. La Guardia. Referred to the House calendar and ordered printed March 2, 1932.

The effects of traffic radar guns on law enforcement officers : hearing before the Ad Hoc Subcommittee on Consumer and Environmental Issues of the Committee on Governmental Affairs, United States Senate, One Hundred Second Congress, second session, August 10, 1992.

Includes bibliographical references.

Amending section 161 of the revised statutes with respect to the authority of federal officers and agencies to withhold information and limit the availability of records.

At head of title: 85th Congress, 2d session, Senate report ; no. 1621.

Theoretical study to determine the sea state limit for the survival of oil slicks on the ocean /

Final report; issued June 1977.

Study of anticipated impact on DOE programs from proposed reduction to the external occupational radiation exposure limit.

Includes bibliographical references.

Study of anticipated impact on DOE programs from proposed reductions to the external occupational radiation exposure limit.

"DOE/EV-0045 (Rev. 2-81)."

Housing finance : implications of alternative methods of adjusting the conforming loan limit : report to Congressional requesters /

"B-257364"--P. 1.