376 research outputs found

    Recidivism Measurement And Sanction Effectiveness In Youth Diversion Programs

    Get PDF
    With the rapid growth of juvenile offender diversion programs, which use many nontraditional sanctions, the effectiveness of sanction combinations in juvenile diversion programs and in each individual program needs to be evaluated. Those making sanctioning decisions currently do so based on intuition rather than using an evidence- or theory-based approach. Considerable research has examined the relationship between offender risk factors and recidivism (who is more likely to reoffend?) and between offender risk factors and sanctions (who is more likely to receive what sanctions?), but little is known about the relationship between sanctions and recidivism (which sanctions best reduce recidivism and for whom?). Furthermore, recidivism studies vary drastically in how they measure or quantify recidivism. This variability of approach makes comparing studies difficult and provides a less-than-complete picture of recidivism in general. The present study used data from one specific youth diversion program to test certain hypotheses of sanctioning by developing and testing a model for assigning sanction combinations to certain offenders on the basis of their individual characteristics. The study first developed measurement models for Offender Risk Propensity, Multiplicity of Sanctions, and Recidivism using structural equation modeling (SEM). Then predictive models were developed to test specific relationships. Understanding the effectiveness of certain sanction packages on certain offenders can form the basis for effective sanctioning in youth diversion programs. This study sought to answer three research questions: What is the best way to measure recidivism? Does completion of a restorative justice program reduce recidivism? Which sanctions, if any, reduce recidivism for specific offender types? To answer the first question: a iv multi-indicator latent construct of recidivism did a very good job of measuring variation in recidivism. Multiple indicators analyzed simultaneously produced a robust tool that can be used in other recidivism studies and help to reduce comparability issues between studies. The recidivism construct, when tested as a function of completion of the restorative justice program, was seen to produce a significant model having an overall good fit with the data. Thus to answer the second research question: offenders’ completion status for the restorative justice program was shown to be a significant predictor of the latent construct of recidivism at the 0.05 level (two-tailed), with those who failed to complete (or chose not to participate) having higher recidivism than did those who completed the program. To answer the third research question: the assignment of specific sanctions (both those suggested by research and theory and those traditionally assigned by this and similar programs) on the entire data set (and on various subsets) of this study have no statistically significant impact on recidivism at the 0.05 level (two-tailed). The findings suggest many policy implications. Consistency is all but nonexistent in recidivism measurements in the academic literature and in program review studies. A multiindicator latent construct of recidivism, such as the one proposed and proven effective in this study, provides a more complete picture than simply conceptualizing recidivism by one dummy variable. This recidivism model can be used as the endogenous variable to evaluate programs and their practices and could reduce the problem of study comparability. This could lead to a better understanding of program characteristics and their impact on offender success. This study also found that completion of the Neighborhood Restorative Justice Program was a significant predictor of recidivism, yet none of the eleven most commonly assigned v sanctions were seen to have a significant impact on recidivism for any subgroup. Proponents of restorative justice argue that it is the programs’ characteristics and not their specific activities that make the programs successful. Reintegrative Shaming Theory and Labeling Theory support this claim and suggest the best approach to address youth criminal behavior is to admonish the act and not the actor, have the offender and community agree on a plan to make the community whole after that criminal act, and prevent repeated interaction with the formal criminal justice system which encourages the youth to see themself as a deviant and engage in further deviant behavior. These characteristics should be further examined and widely employed if confirmed

    Fluctuation Theorem with Information Exchange: Role of Correlations in Stochastic Thermodynamics

    Full text link
    We establish the fluctuation theorem in the presence of information exchange between a nonequilibrium system and other degrees of freedom such as an observer and a feedback controller, where the amount of information exchange is added to the entropy production. The resulting generalized second law sets the fundamental limit of energy dissipation and energy cost during the information exchange. Our results apply not only to feedback-controlled processes but also to a much broader class of information exchanges, and provides a unified framework of nonequilibrium thermodynamics of measurement and feedback control.Comment: To appear in PR

    Does a Computer have an Arrow of Time?

    Get PDF
    In [Sch05a], it is argued that Boltzmann's intuition, that the psychological arrow of time is necessarily aligned with the thermodynamic arrow, is correct. Schulman gives an explicit physical mechanism for this connection, based on the brain being representable as a computer, together with certain thermodynamic properties of computational processes. [Haw94] presents similar, if briefer, arguments. The purpose of this paper is to critically examine the support for the link between thermodynamics and an arrow of time for computers. The principal arguments put forward by Schulman and Hawking will be shown to fail. It will be shown that any computational process that can take place in an entropy increasing universe, can equally take place in an entropy decreasing universe. This conclusion does not automatically imply a psychological arrow can run counter to the thermodynamic arrow. Some alternative possible explana- tions for the alignment of the two arrows will be briefly discussed.Comment: 31 pages, no figures, publication versio

    Numerical Modeling of Propellant Boiloff in Cryogenic Storage Tank

    Get PDF
    This Technical Memorandum (TM) describes the thermal modeling effort undertaken at Marshall Space Flight Center to support the Cryogenic Test Laboratory at Kennedy Space Center (KSC) for a study of insulation materials for cryogenic tanks in order to reduce propellant boiloff during long-term storage. The Generalized Fluid System Simulation program has been used to model boiloff in 1,000-L demonstration tanks built for testing the thermal performance of glass bubbles and perlite insulation. Numerical predictions of boiloff rate and ullage temperature have been compared with the measured data from the testing of demonstration tanks. A satisfactory comparison between measured and predicted data has been observed for both liquid nitrogen and hydrogen tests. Based on the experience gained with the modeling of the demonstration tanks, a numerical model of the liquid hydrogen storage tank at launch complex 39 at KSC was built. The predicted boiloff rate of hydrogen has been found to be in good agreement with observed field data. This TM describes three different models that have been developed during this period of study (March 2005 to June 2006), comparisons with test data, and results of parametric studies

    Numerical Modeling of Propellant Boil-Off in a Cryogenic Storage Tank

    Get PDF
    A numerical model to predict boil-off of stored propellant in large spherical cryogenic tanks has been developed. Accurate prediction of tank boil-off rates for different thermal insulation systems was the goal of this collaboration effort. The Generalized Fluid System Simulation Program, integrating flow analysis and conjugate heat transfer for solving complex fluid system problems, was used to create the model. Calculation of tank boil-off rate requires simultaneous simulation of heat transfer processes among liquid propellant, vapor ullage space, and tank structure. The reference tank for the boil-off model was the 850,000 gallon liquid hydrogen tank at Launch Complex 39B (LC- 39B) at Kennedy Space Center, which is under study for future infrastructure improvements to support the Constellation program. The methodology employed in the numerical model was validated using a sub-scale model and tank. Experimental test data from a 1/15th scale version of the LC-39B tank using both liquid hydrogen and liquid nitrogen were used to anchor the analytical predictions of the sub-scale model. Favorable correlations between sub-scale model and experimental test data have provided confidence in full-scale tank boil-off predictions. These methods are now being used in the preliminary design for other cases including future launch vehicle

    NUMERICAL MODELING OF PROPELLANT BOIL-OFF IN A CRYOGENIC STORAGE TANK

    Get PDF
    ABSTRACT A numerical model to predict boil-off of stored propellant in large spherical cryogenic tanks has been developed. Accurate prediction of tank boil-off rates for different thermal insulation systems was the goal of this collaborative effort. The Generalized Fluid System Simulation Program, which integrates flow analysis and conjugate heat transfer for solving complex fluid system problems, was used to create the model. Calculation of tank boil-off rate requires simultaneous simulation of heat transfer processes among liquid propellant, vapor ullage space, and tank structure. The reference tank for the boil-off model was the 850,000 gallon liquid hydrogen tank at Launch Complex 39B (LC-39B) at Kennedy Space Center, which is under study for future infrastructure improvements to support the Constellation program. The methodology employed in the numerical model was validated using a sub-scale model and tank. Experimental test data from a 1/15 th scale version of the LC-39B tank using both liquid hydrogen and liquid nitrogen were used to anchor the analytical predictions of the subscale model. Favorable correlations between sub-scale model and experimental test data have provided confidence in full-scale tank boil-off predictions. These methods are now being used in the preliminary design for other cases including future launch vehicles

    Consequences of temperature fluctuations in observables measured in high energy collisions

    Full text link
    We review the consequences of intrinsic, nonstatistical temperature fluctuations as seen in observables measured in high energy collisions. We do this from the point of view of nonextensive statistics and Tsallis distributions. Particular attention is paid to multiplicity fluctuations as a first consequence of temperature fluctuations, to the equivalence of temperature and volume fluctuations, to the generalized thermodynamic fluctuations relations allowing us to compare fluctuations observed in different parts of phase space, and to the problem of the relation between Tsallis entropy and Tsallis distributions. We also discuss the possible influence of conservation laws on these distributions and provide some examples of how one can get them without considering temperature fluctuations.Comment: Revised version of the invited contribution to The European Physical Journal A (Hadrons and Nuclei) topical issue about 'Relativistic Hydro- and Thermodynamics in Nuclear Physics' guest eds. Tamas S. Biro, Gergely G. Barnafoldi and Peter Va

    Maf1, a New Player in the Regulation of Human RNA Polymerase III Transcription

    Get PDF
    BACKGROUND: Human RNA polymerase III (pol III) transcription is regulated by several factors, including the tumor suppressors P53 and Rb, and the proto-oncogene c-Myc. In yeast, which lacks these proteins, a central regulator of pol III transcription, called Maf1, has been described. Maf1 is required for repression of pol III transcription in response to several signal transduction pathways and is broadly conserved in eukaryotes. METHODOLOGY/PRINCIPAL FINDINGS: We show that human endogenous Maf1 can be co-immunoprecipitated with pol III and associates in vitro with two pol III subunits, the largest subunit RPC1 and the α-like subunit RPAC2. Maf1 represses pol III transcription in vitro and in vivo and is required for maximal pol III repression after exposure to MMS or rapamycin, treatments that both lead to Maf1 dephosphorylation. CONCLUSIONS/SIGNIFICANCE: These data suggest that Maf1 is a major regulator of pol III transcription in human cells

    Conformational Dynamics of Single pre-mRNA Molecules During \u3cem\u3eIn Vitro\u3c/em\u3e Splicing

    Get PDF
    The spliceosome is a complex small nuclear RNA (snRNA)-protein machine that removes introns from pre-mRNAs via two successive phosphoryl transfer reactions. The chemical steps are isoenergetic, yet splicing requires at least eight RNA-dependent ATPases responsible for substantial conformational rearrangements. To comprehensively monitor pre-mRNA conformational dynamics, we developed a strategy for single-molecule FRET (smFRET) that uses a small, efficiently spliced yeast pre-mRNA, Ubc4, in which donor and acceptor fluorophores are placed in the exons adjacent to the 5′ and 3′ splice sites. During splicing in vitro, we observed a multitude of generally reversible time-and ATP-dependent conformational transitions of individual pre-mRNAs. The conformational dynamics of branchpoint and 3′-splice site mutants differ from one another and from wild type. Because all transitions are reversible, spliceosome assembly appears to be occurring close to thermal equilibrium
    corecore