Hidden degree of freedom and critical states in a two-dimensional electron gas in the presence of a random magnetic field

We establish the existence of a hidden degree of freedom and the critical states of a spinless electron system in a spatially-correlated random magnetic field with vanishing mean. Whereas the critical states are carried by the zero-field contours of the field landscape, the hidden degree of freedom is recognized as being associated with the formation of vortices in these special contours. It is argued that, as opposed to the coherent backscattering mechanism of weak localization, a new type of scattering processes in the contours controls the underlying physics of localization in the random magnetic field system. In addition, we investigate the role of vortices in governing the metal-insulator transition and propose a renormalization-group diagram for the system under study.Comment: 17 pages, 16 figures; Figs. 1, 7, 9, and 10 have been reduced in quality for e-submissio

Splenectomy for splenomegaly and secondary hypersplenism

Splenomegaly and secondary hypersplenism may be associated with acute and chronic infections, autoimmune states, portal hypertension or splenic vein thrombosis, and a number of infiltrative and neoplastic conditions involving the spleen. Our experience and that of others with these various conditions demonstrates that the decision to perform splenectomy should be based on well-defined and often strictly limited indications. Except for idiopathic splenomegaly, the presence and severity of secondary hypersplenism or severely symptomatic splenomegaly should be well documented. In each case, the potential for palliation and known mean duration of expected response must be weighed against the increased morbidity and mortality of splenectomy (as compared to operation for “primary” hypersplenism) . La splénomégalie avec hypersplénisme secondaire relève de multiples causes: infection aigue ou chronique, états autoimmunologiques, hypertension portale, thrombose de la veine splénique, lésions tumorales spléniques. L'expérience de l'auteur qui rejoint celle de nombreux collègues lui permet d'affirmer que les indications de la splénectomie doivent être bien définies et sont strictement limitées. A l'exception de la splénomégalie idiopathique, l'existence et l'intensité de l'hypersplénisme, l'importance des symptomes provoqués par la splénomégalie doivent être aprréciées avec précision. Dans chaque cas le potentiel de la rémission de l'affection et la durée de la rémission doivent être pris en considération en fonction de l'éventuelle morbidité et de l'éventuelle mortalité de la splénectomie (par comparaison avec la splénectomie pour hypersplénisme primaire). Eplenomegalia e hiperesplenismo secundario pueden estar asociados con infecciones agudas y crónicas, estados autoinmunes (síndrome de Felty, lupus eritematoso sistémico), “esplenomegalia congestiva” por hipertensión portal o trombosis de la vena esplénica y con una variedad de entidades de tipo infiltrativo y neoplásico que afectan al bazo (sarcoidosis, enfermedad de Gaucher, varios desórdenes mieloproliferativos y linfomas). Nuestra experiencia, y aquella de otros autores, con tales condiciones demuestra que la decisión de realizar esplenectomía debe estar fundamentada en indicaciones bien definidas y estrictamente limitadas. Excepto en casos de esplenomegalia idiopática, la presencia y severidad del hiperesplenismo secundario o de esplenomegalia severamente sintomática debe ser bien documentada. En cada caso debe determinarse el potencial de paliación y la duración de la respuesta que se espera obtener frente a la incrementada morbilidad y mortalidad de la esplenectomía (en comparación con la operación que se realiza por hiperesplenismo “primario”).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41318/1/268_2005_Article_BF01655279.pd

Police-initiated diversion for youth to prevent future delinquent behavior: a systematic review

BackgroundOverly punitive responses to youth misconduct may have the unintended consequence ofincreasing the likelihood of future delinquency; yet, overly lenient responses may fail to serveas a corrective for the misbehavior. Police diversion schemes are a collection of strategiespolice can apply as an alternative to court processing of youth. Police-initiated diversionschemes aim to reduce reoffending by steering youth away from deeper penetration into thecriminal justice system and by providing an alternative intervention that can help youthaddress psychosocial development or other needs that contribute to their problem behavior.ObjectivesThe objective of this review was to synthesize the evidence on the effectiveness of pre-courtinterventions involving police warning or counseling and release, and cautioning schemes inreducing delinquent behavior.Search methodsA combination of 26 databases and websites were searched. References of relevant reviewswere also scanned to identify studies. We also consulted with experts in the field. Searcheswere executed by two reviewers and conducted between August 2016 and January 2017.Selection criteriaOnly experimental and quasi-experimental designs were eligible for this review. All quasiexperimentaldesigns must have had a comparison group similar to the police diversionintervention group with respect to demographic characteristics and prior involvement indelinquent behavior (i.e., at similar risk for future delinquent behavior). Additionally, studiesmust have included youth participants between 12 and 17 years of age who either underwenttraditional system processing or were diverted from court processing through a police-leddiversion program. Studies were also eligible if delinquency-related outcomes, includingofficial and non-official (self-report or third-party reporting) measures of delinquency werereported.Data collection and analysisThis study used meta-analysis to synthesize results across studies. This method involvedsystematic coding of study features and conversion of study findings into effect sizesreflecting the direction and magnitude of any police-led diversion effect. There were 19independent evaluations across the 14 primary documents coded for this review. From this,we coded 67 effect sizes of delinquent behavior post diversion across 31 diversion-traditionalprocessing comparisons. We analyzed these comparisons using two approaches. The firstapproach selected a single effect size per comparison based on a decision rule and the secondused all 67 effect sizes, nesting these within comparison condition and evaluation design.ResultsThe general pattern of evidence is positive, suggesting that police-led diversion modestlyreduces future delinquent behavior of low-risk youth relative to traditional processing.Authors’ conclusionsThe findings from this systematic review support the use of police-led diversion for low-riskyouth with limited or no prior involvement with the juvenile justice system. Thus, policedepartments and policy-makers should consider diversionary programs as part of the mix ofsolutions for addressing youth crime

Replanning in a Resource-Based Framework

Abstract. An important aspect of agents is how they construct a plan to reach their goals. Since most agents live in a dynamic environment, they also will often be confronted with situations in which the plans they constructed to reach their goals are no longer feasible. In such situations, agents have to change their plan to deal with the new environment. In this paper we describe such a replanning process using a computational framework, consisting of resources and actions to represent the planned activities of an agent.