85 research outputs found

    Dissipative and Non-dissipative Single-Qubit Channels: Dynamics and Geometry

    Full text link
    Single-qubit channels are studied under two broad classes: amplitude damping channels and generalized depolarizing channels. A canonical derivation of the Kraus representation of the former, via the Choi isomorphism is presented for the general case of a system's interaction with a squeezed thermal bath. This isomorphism is also used to characterize the difference in the geometry and rank of these channel classes. Under the isomorphism, the degree of decoherence is quantified according to the mixedness or separability of the Choi matrix. Whereas the latter channels form a 3-simplex, the former channels do not form a convex set as seen from an ab initio perspective. Further, where the rank of generalized depolarizing channels can be any positive integer upto 4, that of amplitude damping ones is either 2 or 4. Various channel performance parameters are used to bring out the different influences of temperature and squeezing in dissipative channels. In particular, a noise range is identified where the distinguishability of states improves inspite of increasing decoherence due to environmental squeezing.Comment: 12 pages, 4 figure

    Treino cognitivo em idosos e efeitos nas funções executivas

    Get PDF
    El envejecimiento se asocia comúnmente con el deterioro cognitivo y la pérdida de otras capacidades, lo cual conlleva la necesidad de investigar elementos que puedan contribuir a las intervenciones preventivas de rehabilitación cognitiva y que tienen como objetivo garantizar la calidad de vida de los ancianos. El objetivo de este estudio fue caracterizar ancianos que se inscribieron en esta intervención, para medir los efectos del entrenamiento cognitivo, con énfasis en las funciones ejecutivas, comparando un grupo experimental con un grupo control. Se trata de una investigación cuantitativa, con un diseño cuasi-experimental; es correlacional y comparativa, con pre y post-test e intervención. La muestra estuvo conformada por 83 ancianos, dividida en un grupo experimental (GE) (45 personas) y un grupo control (GC) (38 personas). Se utilizaron los siguientes instrumentos: entrevista neuropsicológica semiestructurada sobre características sociodemográficas; Examen Mínimo del Estado Mental (Mini Mental State o MMSE, por sus siglas en inglés); Inventario de Ansiedad Beck (BAI, por sus siglas en inglés); Escala de Depresión Geriátrica (GDS, por sus siglas en inglés); subpruebas WAIS-III: prueba de amplitud de dígitos (Digit Span), vocabulario, diseño con bloques, codificación, Secuenciación de Letras y Números (LNS por sus siglas en inglés), y la búsqueda de símbolos; Test de Trazos (TMT por sus siglas en inglés); Figuras Complejas de Rey; Paradigma de Sternberg; tareas de fluidez verbal sobre semántica (animales) y fonemas (F-A-S); Prueba de Aprendizaje Verbal-auditiva de Rey (RVLT por sus siglas en inglés); Prueba de Stroop: colores y palabras; tareas ir/no ir; y Test Wisconsin de Clasificación de Cartas (WCST por sus siglas en inglés). Los resultados de la comparación entre los grupos mostraron que hubo una diferencia significativa en cuanto al número de errores en el Paradigma de Sternberg y las categorías completas del WCST. Las comparaciones intragrupales mostraron que el GE tuvo mejores resultados después de la intervención en las siguientes pruebas: GDS, RAVLT, Figuras Complejas de Rey (memoria), prueba de amplitud de dígitos y vocabulario.O envelhecimento está comumente relacionado ao declínio cognitivo e a outras perdas de diferentes habilidades, o que aponta a necessidade de buscar elementos que possam contribuir para intervenções preventivas de reabilitação cognitiva, que tenham como objetivo assegurar uma melhor qualidade de vida do idoso. O objetivo deste estudo é caracterizar os idosos participantes, mensurar os efeitos do treino cognitivo, com ênfase nas funções executivas, comparados a um grupo controle. Trata-se de uma pesquisa do tipo quantitativa, com delineamento quase experimental, correlacional e comparativa com pré e pós-teste e de intervenção. Houve grupo controle para comparação. A mostra foi composta por 83 idosos da população geral, divididos em 45 idosos que fizeram parte do Grupo Experimental (GE) e 38 idosos participantes do Grupo Controle (GC). Instrumentos utilizados: Entrevista neuropsicológica sociodemográfica; Mini Exame do Estado Mental (MEEM); Inventário de Ansiedade de Beck (BAI); Escala de Depressão Geriátrica (GDS); Subtestes Dígitos, Vocabulário, Cubos, Código, Sequência Números e Letras (SNL); Procurar Símbolos (WAIS-III) ; Trail Makint Test (TMT); Figuras Complexas de Rey; Paradigma de Sternberg; Tarefas de fluência verbal (letras F, A, S); Rey Auditory-Verbal Learning Test (RVLT); Teste Stroop; Tarefas go-no-go e Teste Wisconsin (WCST). Os resultados mostraram na comparação entre os grupos, que houve diferença significativa quanto à variação no número de erros no Paradigma de Sternberg, Categorias Completadas do WCST e Procurar Símbolos. Nas comparações intragrupo, o Grupo Experimental melhorou significativamente os escores após a intervenção dos instrumentos GDS, RAVLT, Figuras Complexas de Rey–memória, Dígitos OD, Dígitos Total e Vocabulário.Aging is commonly associated with cognitive decline and loss of other abilities, which leads to the need for researching elements that may contribute to preventive cognitive rehabilitation interventions aiming to guarantee the elderly a good quality of life. The objective of this study is to characterize elderly who enrolled in this intervention, to measure the effects of cognitive training with emphasis on executive functions, by comparing an Experimental to a Control group. This is a quantitative research that used a quasi-experimental design; it is correlational and comparative, involving pre- and posttesting and intervention. The sample was formed by 83 elders, split into an Experimental Group (EG) (45 people) and a Control Group (GC) (38 people). The instruments used were the following: a neuropsychological semi-structured interview about sociodemographic characteristics; Mini Mental State Examination (MMSE); Beck Anxiety Inventory (BAI); Geriatric Depression Scale (GDS); WAIS-III subtests: Digit Span, Vocabulary, Block Design, Coding, Letter-Number Sequencing (LNS), and Symbol Search; Trail Making Test (TMT); Ray Complex Figures; Sternberg Paradigm; verbal fluency tasks about semantics (animals) and phonemes (F-A-S); Rey Auditory-Verbal Learning Test (RVLT); Stroop Test: colors and words; go/ no go tasks; and the Wisconsin Card Sorting Test (WCST). The results from the comparison between groups showed that there was a significant difference regarding the number of errors in the Sternberg Paradigm and Completed Categories of the WCST. Intragroup comparisons showed that the EG had better results after the intervention on the following tests: GDS, RAVLT, Rey Complex Figures (memory), Digit Span and Vocabulary

    Synergistic growth inhibition by Iressa and Rapamycin is modulated by VHL mutations in renal cell carcinoma

    Get PDF
    Epidermal growth factor receptor (EGFR) and tumour growth factor alpha (TGFα) are frequently overexpressed in renal cell carcinoma (RCC) yet responses to single-agent EGFR inhibitors are uncommon. Although von Hippel–Lindau (VHL) mutations are predominant, RCC also develops in individuals with tuberous sclerosis (TSC). Tuberous sclerosis mutations activate mammalian target of rapamycin (mTOR) and biochemically resemble VHL alterations. We found that RCC cell lines expressed EGFR mRNA in the near-absence of other ErbB family members. Combined EGFR and mTOR inhibition synergistically impaired growth in a VHL-dependent manner. Iressa blocked ERK1/2 phosphorylation specifically in wt-VHL cells, whereas rapamycin inhibited phospho-RPS6 and 4E-BP1 irrespective of VHL. In contrast, phospho-AKT was resistant to these agents and MYC translation initiation (polysome binding) was similarly unaffected unless AKT was inhibited. Primary RCCs vs cell lines contained similar amounts of phospho-ERK1/2, much higher levels of ErbB-3, less phospho-AKT, and no evidence of phospho-RPS6, suggesting that mTOR activity was reduced. A subset of tumours and cell lines expressed elevated eIF4E in the absence of upstream activation. Despite similar amounts of EGFR mRNA, cell lines (vs tumours) overexpressed EGFR protein. In the paired cell lines, PRC3 and WT8, EGFR protein was elevated post-transcriptionally in the VHL mutant and EGF-stimulated phosphorylation was prolonged. We propose that combined EGFR and mTOR inhibitors may be useful in the subset of RCCs with wt-VHL. However, apparent differences between primary tumours and cell lines require further investigation

    Punishing Terrorists: A Re-Examination of U.S. Federal Sentencing in the Postguidelines Era

    Get PDF
    The empirical literature on the theory and practice of sentencing politically motivated offenders such as terrorists in U.S. federal courts is limited. Thus, we know relatively little about the dealings between terrorist offenders and the criminal justice system or how these interactions may be influenced by changes in American legal or political context. This study summarizes previous findings relative to sentencing disparity among terrorists and nonterrorists in U.S. federal courts prior to the imposition of the U.S. Sentencing Guidelines. We then identify events occurring after the advent of the guidelines, including the early acts of terrorism on American soil. We evaluate the sentencing of terrorists versus nonterrorists following the confluence imposition of the guidelines and these events. We determine whether and how the sentencing disparity between terrorist and nonterrorist has changed since the implementation of the U.S. Sentencing Guidelines and the terrorist events of the early 1990s. Based on our findings, we put forth suggestions as to the possible ways these conditions may have affected sentencing outcomes.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline
    • …
    corecore