Central-cell And Screening Effects On The Binding Energies Of Neutral Chalcogen Impurities In Silicon

The binding energies of D0 states in S-, Se-, and Te-doped silicon crystals are calculated within a variational scheme in the effective-mass approximation and with a Chandrasekhar-type variational function for the two-electron envelopes. Central cells are modeled with a constant core potential within the impurity sphere. Screening effects for the potential and the electron-electron interaction are taken into account by means of a position-dependent dielectric function. Results are compared with recent theoretical and experimental work. It is found that central-cell effects and position-dependent screening are essential to account for the experimental data. © 1986 The American Physical Society.33128765876

Influence Of Maturity Stage On Fruit Longevity Of Cherry Tomatoes Stored At Ambient And Controlled Temperature

Fruit maturity stage has direct influence on the post-harvest life and consumer quality. Therefore, the understanding of the maturation process and its quality characteristics for storage are key factors for commercialization. In face of the foregoing, this study aimed to determine shelf life and changes in physical and chemical indexes of cherry tomatoes (Perinha Água Branca (PAB) and Mascot), assessing fruit harvested at four maturity stages and stored at ambient and controlled temperatures. For this, it was used fruit at turning, pink, red and ripe maturity stages, submitted to ambient (25 ± 2 °C) and controlled (12 °C and 90% RH) temperature, and assessed over time the indexes of fresh mass loss, titratable acidity, pH, soluble solids and ascorbic acid. The experimental design was completely randomized design in a factorial scheme of 2×4×7 for ambient temperature and 2×4×8 for controlled temperature. At ambient temperature, a longevity of up to 20 days was observed for PAB and Mascot fruit harvested at turning and pink maturity stages. When harvested at red and ripe stages, the longevity was of 15 days for PAB fruit and of 15 and 11 days, respectively, for Mascot fruit. At controlled temperature, PAB fruit showed longevity of 24 days when harvested at turning and pink stages and of 20 and 7 days, respectively, when harvested at red and ripe stages. A longevity of up to 27 days was observed for Mascot fruit harvested at turning stage and of 24 days for the other stages. The fruit harvested at turning and pink maturity stages, associated with storage under controlled conditions, presented higher longevity and maintenance of physical and chemical indexes of quality.3764027403

Texture analysis of computed tomography images of acute ischemic stroke patients

Computed tomography (CT) images are routinely used to assess ischemic brain stroke in the acute phase. They can provide important clues about whether to treat the patient by thrombolysis with tissue plasminogen activator. However, in the acute phase, the lesions may be difficult to detect in the images using standard visual analysis. The objective of the present study was to determine if texture analysis techniques applied to CT images of stroke patients could differentiate between normal tissue and affected areas that usually go unperceived under visual analysis. We performed a pilot study in which texture analysis, based on the gray level co-occurrence matrix, was applied to the CT brain images of 5 patients and of 5 control subjects and the results were compared by discriminant analysis. Thirteen regions of interest, regarding areas that may be potentially affected by ischemic stroke, were selected for calculation of texture parameters. All regions of interest for all subjects were classified as lesional or non-lesional tissue by an expert neuroradiologist. Visual assessment of the discriminant analysis graphs showed differences in the values of texture parameters between patients and controls, and also between texture parameters for lesional and non-lesional tissue of the patients. This suggests that texture analysis can indeed be a useful tool to help neurologists in the early assessment of ischemic stroke and quantification of the extent of the affected areas.1076107

Lesão expansiva cerebral devida a citomegalovírus: relato de caso e revisão da literatura

Cytomegalovirus (CMV) disease in acquired immunodeficiency syndrome (AIDS) patients most commonly presents as chorioretinitis and gastro-intestinal infection. Neurological involvement due to CMV may cause several clinical presentations: polyradiculitis, myelitis, encephalitis, ventriculo-encephalitis, and mononeuritis multiplex. Rarely, cerebral mass lesion is described. We report a 39 year-old woman with AIDS and previous cerebral toxoplasmosis. She presented with fever, seizures, and vulval ulcers. Her chest X-ray showed multiple lung nodules, and a large frontal lobe lesion was seen in a brain computed tomography scan. She underwent a brain biopsy through a frontal craniotomy, but her condition deteriorated and she died in the first postoperative day. Histopathological studies and immunohistochemistry disclosed CMV disease, and there was no evidence of cerebral toxoplasmosis, bacterial, mycobacterial or fungal infection. CMV disease should be considered in the differential diagnosis of cerebral mass lesion in AIDS patients. High suspicion index, timely diagnostic procedures (surgical or minimally invasive), and proper utilization of prophylactic and therapeutic medication could improve outcome of these patients.As doenças causadas pelo citomegalovírus (CMV) em pacientes com a síndrome da imunodeficiência adquirida apresentam-se principalmente como corioretinite ou comprometimento gastrointestinal. No sistema nervoso central, o CMV pode causar diversas síndromes clínicas: poliradiculite, mielite, encefalite, ventrículo-encefalite e mononeurite múltipla. Raramente, lesões expansivas cerebrais são descritas. Os autores relatam o caso de uma paciente de 39 anos com antecedentes de infecção pelo HIV e toxoplasmose cerebral, que apresentou-se com febre, convulsões e úlceras vulvares. O raios-X de tórax demonstrou múltiplos nódulos pulmonares e a tomografia computadorizada de crânio evidenciou extensa lesão no lobo frontal esquerdo. Após ser submetida à craniotomia, evoluiu com piora clínica, falecendo no primeiro dia de pós-operatório. Os estudos histopatológicos e imunohistoquímicos demonstraram doença citomegálica. Foram excluídas toxoplasmose cerebral e infecção bacteriana, micobacteriana ou fúngica. Concluímos que, embora seja extremamente raro, o CMV deve ser considerado no diagnóstico diferencial das lesões expansivas cerebrais em pacientes com infecção pelo HIV. Um elevado índice de suspeita, procedimentos diagnósticos oportunos (cirúrgicos ou minimamente invasivos), e o adequado uso de antivirais (terapêuticos e profiláticos) podem melhorar o prognóstico desta letal manifestação

Segmented lordotic angles to assess lumbosacral transitional vertebra on EOS

Purpose: To test the vertical posterior vertebral angles (VPVA) of the most caudal lumbar segments measured on EOS to identify and classify the lumbosacral transitional vertebra (LSTV). Methods: We reviewed the EOS examinations of 906 patients to measure the VPVA at the most caudal lumbar segment (cVPVA) and at the immediately proximal segment (pVPVA), with dVPVA being the result of their difference. Mann\u2013Whitney, Chi-square, and ROC curve statistics were used. Results: 172/906 patients (19%) had LSTV (112 females, mean age: 43 \ub1 21 years), and 89/172 had type I LSTV (52%), 42/172 type II (24%), 33/172 type III (19%), and 8/172 type IV (5%). The cVPVA and dVPVA in non-articulated patients were significantly higher than those of patients with LSTV, patients with only accessory articulations, and patients with only bony fusion (all p <.001). The cVPVA and dVPVA in L5 sacralization were significantly higher than in S1 lumbarization (p <.001). The following optimal cutoff was found: cVPVA of 28.2\ub0 (AUC = 0.797) and dVPVA of 11.1\ub0 (AUC = 0.782) to identify LSTV; cVPVA of 28.2\ub0 (AUC = 0.665) and dVPVA of 8\ub0 (AUC = 0.718) to identify type II LSTV; cVPVA of 25.5\ub0 (AUC = 0.797) and dVPVA of 12 7.5\ub0 (AUC = 0.831) to identify type III\u2013IV LSTV; cVPVA of 20.4\ub0 (AUC = 0.693) and dVPVA of 12 1.8\ub0 (AUC = 0.665) to differentiate type II from III\u2013IV LSTV; cVPVA of 17.9\ub0 (AUC = 0.741) and dVPVA of 12 4.5\ub0 (AUC = 0.774) to differentiate L5 sacralization from S1 lumbarization. Conclusion: The cVPVA and dVPVA measured on EOS showed good diagnostic performance to identify LSTV, to correctly classify it, and to differentiate L5 sacralization from S1 lumbarization

The Atp-dependent Rna Helicase Hrpb Plays An Important Role In Motility And Biofilm Formation In Xanthomonas Citri Subsp. Citri

Background: RNA helicases are enzymes that catalyze the separation of double-stranded RNA (dsRNA) using the free energy of ATP binding and hydrolysis. DEAD/DEAH families participate in many different aspects of RNA metabolism, including RNA synthesis, RNA folding, RNA-RNA interactions, RNA localization and RNA degradation. Several important bacterial DEAD/DEAH-box RNA helicases have been extensively studied. In this study, we characterize the ATP-dependent RNA helicase encoded by the hrpB (XAC0293) gene using deletion and genetic complementation assays. We provide insights into the function of the hrpB gene in Xanthomonas citri subsp. citri by investigating the roles of hrpB in biofilm formation on abiotic surfaces and host leaves, cell motility, host virulence of the citrus canker bacterium and growth in planta. Results: The hrpB gene is highly conserved in the sequenced strains of Xanthomonas. Mutation of the hrpB gene (Δ;hrpB) resulted in a significant reduction in biofilms on abiotic surfaces and host leaves. Δ;hrpB also exhibited increased cell dispersion on solid medium plates. Δ;hrpB showed reduced adhesion on biotic and abiotic surfaces and delayed development in disease symptoms when sprayed on susceptible citrus leaves. Quantitative reverse transcription-PCR assays indicated that deletion of hrpB reduced the expression of four type IV pili genes. The transcriptional start site of fimA (XAC3241) was determined using rapid amplification of 5′-cDNA Ends (5′RACE). Based on the results of fimA mRNA structure predictions, the fimA 5′ UTR may contain three different loops. HrpB may be involved in alterations to the structure of fimA mRNA that promote the stability of fimA RNA. Conclusions: Our data show that hrpB is involved in adherence of Xanthomonas citri subsp. citri to different surfaces. In addition, to the best of our knowledge, this is the first time that a DEAH RNA helicase has been implicated in the regulation of type IV pili in Xanthomonas. © 2016 Granato et al.16

Adapting Real Quantifier Elimination Methods for Conflict Set Computation

The satisfiability problem in real closed fields is decidable. In the context of satisfiability modulo theories, the problem restricted to conjunctive sets of literals, that is, sets of polynomial constraints, is of particular importance. One of the central problems is the computation of good explanations of the unsatisfiability of such sets, i.e.\ obtaining a small subset of the input constraints whose conjunction is already unsatisfiable. We adapt two commonly used real quantifier elimination methods, cylindrical algebraic decomposition and virtual substitution, to provide such conflict sets and demonstrate the performance of our method in practice