7,100 research outputs found

    Exact Finite-Size-Scaling Corrections to the Critical Two-Dimensional Ising Model on a Torus

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    We analyze the finite-size corrections to the energy and specific heat of the critical two-dimensional spin-1/2 Ising model on a torus. We extend the analysis of Ferdinand and Fisher to compute the correction of order L^{-3} to the energy and the corrections of order L^{-2} and L^{-3} to the specific heat. We also obtain general results on the form of the finite-size corrections to these quantities: only integer powers of L^{-1} occur, unmodified by logarithms (except of course for the leading logL\log L term in the specific heat); and the energy expansion contains only odd powers of L^{-1}. In the specific-heat expansion any power of L^{-1} can appear, but the coefficients of the odd powers are proportional to the corresponding coefficients of the energy expansion.Comment: 26 pages (LaTeX). Self-unpacking file containing the tex file and three macros (indent.sty, eqsection.sty, subeqnarray.sty). Added discussions on the results and new references. Version to be published in J. Phys.

    Canonical Equivalence of a Generic 2D Dilaton Gravity Model and a Bosonic String Theory

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    We show that a canonical tranformation converts, up to a boundary term, a generic 2d dilaton gravity model into a bosonic string theory with a Minkowskian target space.Comment: LaTeX file, 9 pages, no figure

    On The Reduced Canonical Quantization Of The Induced 2D-Gravity

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    The quantization of the induced 2d-gravity on a compact spatial section is carried out in three different ways. In the three approaches the supermomentum constraint is solved at the classical level but they differ in the way the hamiltonian constraint is imposed. We compare these approaches establishing an isomorphism between the resulting Hilbert spaces.Comment: 17 pages, plain LaTeX. FTUV/93-15, IFIC/93-10, Imperial-TP/93-94/1

    REAM intensity modulator-enabled 10Gb/s colorless upstream transmission of real-time optical OFDM signals in a single-fiber-based bidirectional PON architecture

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    Reflective electro-absorption modulation-intensity modulators (REAM-IMs) are utilized, for the first time, to experimentally demonstrate colorless ONUs in single-fiber-based, bidirectional, intensity-modulation and direct-detection (IMDD), optical OFDM PONs (OOFDM-PONs) incorporating 25km SSMFs and OLT-side-seeded CW optical signals. The colorlessness of the REAM-IMs is characterized, based on which optimum REAM-IM operating conditions are identified. In the aforementioned PON architecture, 10Gb/s colorless upstream transmissions of end-to-end realtime OOFDM signals are successfully achieved for various wavelengths within the entire C-band. Over such a wavelength window, corresponding minimum received optical powers at the FEC limit vary in a range as small as <0.5dB. In addition, experimental measurements also indicate that Rayleigh backscattering imposes a 2.8dB optical power penalty on the 10Gb/s over 25km upstream OOFDM signal transmission. Furthermore, making use of on-line adaptive bit and power loading, a linear trade-off between aggregated signal line rate and optical power budget is observed, which shows that, for the present PON system, a 10% reduction in signal line rate can improve the optical power budget by 2.6dB. © 2012 Optical Society of America

    An epidemiological study of burglary offenders: trends and predictors of self-reported arrests for burglary in the United States, 2002-2013

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    Burglary is serious property crime with a relatively high incidence and has been shown to be variously associated with other forms of criminal behavior. Unfortunately, an epidemiological understanding of burglary and its correlates is largely missing from the literature. Using public-use data collected between 2002 and 2013 as part of the National Survey on Drug Use and Health (NSDUH), the current study compared those who self-reported burglary arrest in the prior 12 months with and without criminal history. The unadjusted prevalence estimates of self-reported burglary arrest were statistically different for those with a prior arrest history (4.7%) compared with those without an arrest history (0.02%) which is a 235-fold difference. Those with an arrest history were more likely to report lower educational attainment, to have lower income, to have moved more than 3 times in the past 5 years, and to use alcohol, tobacco, illicit drugs, and engage in binge drinking. Moreover, those with prior arrest histories were younger and more likely to be male. There is considerable heterogeneity among burglars with criminal history indicating substantially greater behavioral risk

    Trends and correlates of substance use disorders among probationers and parolees in the United States 2002–2014

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    BACKGROUND: Substance use and crime/recidivism are irrevocably linked. We explore the nuances of this association by highlighting the prevalence, trends, and correlates of substance use dsorders in a large group of probationers/parolees. METHODS: We examined SUDs among probationers and parolees in the United States using data from the National Study on Drug Use and Health (NSDUH). Logistic regression models were computed to examine eight distinct outcomes: alcohol abuse, illicit drug abuse, marijuana/hashish abuse, comorbid alcohol and illicit drug abuse, alcohol dependence, illicit drug dependence, marijuana/hashish dependence, and comorbid alcohol and illicit drug dependence. RESULTS: Probationers/parolees have high prevalence rates across all SUDs categories and these trends have been relatively constant. Prevalence rates for alcohol abuse and dependence are two to six times higher than for marijuana and other illicit drug abuse and dependence. Key correlates of substance abuse for probationers/parolees include: age, gender, race/ethnicity, education, income, risk propensity, crime/violence measures, and comorbid substance abuse. Similar correlates were found for substance dependence, in addition to employment and mental health treatment. CONCLUSIONS: This study indicates that SUDs are higher among probationer/parolees as compared to their non-supervised counterparts − between four and nine times higher − and these levels have changed little in recent years. Effectively responding to SUDs in this population may enhance adherence to supervision requirements, prevent recidivism, and improve public safety. We may be better served using limited funds for further development of evidence-based policies and programs, such as drug courts, which demonstrate reductions in both drug use and recidivism

    Diffeomorphisms, Noether Charges and Canonical Formalism in 2D Dilaton Gravity

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    We carry out a parallel study of the covariant phase space and the conservation laws of local symmetries in two-dimensional dilaton gravity. Our analysis is based on the fact that the Lagrangian can be brought to a form that vanishes on-shell giving rise to a well-defined covariant potential for the symplectic current. We explicitly compute the symplectic structure and its potential and show that the requirement to be finite and independent of the Cauchy surface restricts the asymptotic symmetries.Comment: 14 pages, latex with psfig macro, one figur

    Kronecker's Double Series and Exact Asymptotic Expansion for Free Models of Statistical Mechanics on Torus

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    For the free models of statistical mechanics on torus, exact asymptotic expansions of the free energy, the internal energy and the specific heat in the vicinity of the critical point are found. It is shown that there is direct relation between the terms of the expansion and the Kronecker's double series. The latter can be expressed in terms of the elliptic theta-functions in all orders of the asymptotic expansion.Comment: REVTeX, 22 pages, this is expanded version which includes exact asymptotic expansions of the free energy, the internal energy and the specific hea
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