6,117 research outputs found

    A computationally efficient method for calculating the maximum conductance of disordered networks: Application to 1-dimensional conductors

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    Random networks of carbon nanotubes and metallic nanowires have shown to be very useful in the production of transparent, conducting films. The electronic transport on the film depends considerably on the network properties, and on the inter-wire coupling. Here we present a simple, computationally efficient method for the calculation of conductance on random nanostructured networks. The method is implemented on metallic nanowire networks, which are described within a single-orbital tight binding Hamiltonian, and the conductance is calculated with the Kubo formula. We show how the network conductance depends on the average number of connections per wire, and on the number of wires connected to the electrodes. We also show the effect of the inter-/intra-wire hopping ratio on the conductance through the network. Furthermore, we argue that this type of calculation is easily extendable to account for the upper conductivity of realistic films spanned by tunneling networks. When compared to experimental measurements, this quantity provides a clear indication of how much room is available for improving the film conductivity.Comment: 7 pages, 5 figure

    Renormalizability of Nonrenormalizable Field Theories

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    We give a simple and elegant proof of the Equivalence Theorem, stating that two field theories related by nonlinear field transformations have the same S matrix. We are thus able to identify a subclass of nonrenormalizable field theories which are actually physically equivalent to renormalizable ones. Our strategy is to show by means of the BRS formalism that the "nonrenormalizable" part of such fake nonrenormalizable theories, is a kind of gauge fixing, being confined in the cohomologically trivial sector of the theory.Comment: 3 pages, revtex, no figure

    Effectiveness of the ADEC as a level 2 screening test for young children with suspected autism spectrum disorders in a clinical setting

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    Background The Autism Detection in Early Childhood (ADEC) is a clinician-administered, Level 2 screening tool. A retrospective file audit was used to investigate its clinical effectiveness. Method Toddlers referred to an Australian child development service between 2008 and 2010 (N?=?53, M age?=?32.2 months) were screened with the ADEC. Their medical records were reviewed in 2013 when their mean age was 74.5 months, and the original ADEC screening results were compared with later diagnostic outcomes. Results The ADEC had good sensitivity (87.5%) and moderate specificity (62%). Three behaviours predicted autism spectrum disorders (ASDs): response to name, gaze switching, and gaze monitoring (p???.001). Conclusions The ADEC shows promise as a screening tool that can discriminate between young children with ASDs and those who have specific communication disorders or developmental delays that persist into middle childhood but who do not meet the criteria for ASDs

    Effect of clonidine on the target dose of propofol: bispectral index evaluation

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    Background: The increasing evidence associating general anaesthetics with neurotoxicity and post-operative cognitive disturbances, mainly with deeper levels of anaesthetics, has led to more frequent use of adjuvants. This study aimed to analyse the effect of clonidine on the target dose of propofol in total intravenous anaesthesia. Methods: A randomised, double-blind clinical trial was performed in a large hospital located in the southern region of Ceará, Brazil. Fifty-one patients from the anaesthesia outpatient clinic were enrolled. Patients were divided into two groups: one group received 100 mL of 0.9% sterile saline, and the other group received 100 mL of 0.9% sterile saline with clonidine at a dose of 3 µg/kg. A target-controlled infusion pump was used to administer propofol, following the modified Marsh pharmacokinetic model and aiming for a bispectral index (BIS) score of approximately 40 for intubation and 45 for anaesthesia maintenance. The anaesthesiologist was informed which group the patient belonged to after completion of surgery and data recording. Results: The chi-squared test was used to evaluate the distribution of the samples with respect to gender, and the Student’s t-test was used to evaluate the parametric variables. There was no statistically significant difference between the samples. A significant difference was observed in the target dose of propofol between the two groups during the maintenance and awakening phases, but not at the time of intubation. Conclusions: Clonidine pre-operatively administered at a dose of 3 µg/kg significantly reduced the target dose of propofol needed to maintain adequate levels of anaesthesia as measured by BIS

    Oral alterations and oral care in bone marrow transplant patients

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    Os cuidados gerais relativos ao paciente submetido ao transplante de medula óssea (TMO) incluem avaliações odontológicas rotineiras, as quais devem estar inseridas em um contexto multiprofissional. A cavidade oral constitui um sítio propício a infecções com grande potencial de desenvolvimento de bacteremia, sendo que lesões infecciosas devem ser previamente tratadas e controladas pelo cirurgião-dentista. O objetivo desta revisão é discutir questões em destaque na literatura nacional e internacional referentes aos quadros inflamatórios e infecciosos orais de importância para o paciente transplantado de medula óssea, tanto os predisponentes a complicações durante o transplante, quanto os que ocorrem durante e após a terapia mielossupressora. Destaca-se na literatura a doença periodontal avançada, a qual constitui um quadro infeccioso crônico que deve ser evitado ou controlado durante o TMO, principalmente devido à presença de S. viridans. Os fatores de risco para mucosite oral (OM), doença do enxerto contra o hospedeiro (DECH) e xerostomia ainda não estão definidos, principalmente para OM e DECH. São citadas na literatura alternativas promissoras de tratamento para OM, tais como crioterapia, administração de fatores de crescimento e laserterapia. O risco aumentado de cárie é controverso e, dentre as lesões fúngicas e virais, destacam-se as infecções orais e de orofaringe por Candida e pela família de herpesvírus, de importância clínica considerável. Em pacientes pediátricos são relevantes as alterações craniofaciais e dentárias, decorrentes principalmente da radioterapia.General care in bone marrow transplant (BMT) patients includes routine dental evaluations, which must be included in a multi-professional context. The oral cavity is a site that favors infections with high potential for consequent bacteremia and so infectious lesions must be treated or controlled by the dentist. The aim of this review is to discuss key questions in national and international literature with reference to oral inflammatory conditions of BMT patients, both those with predisposition to complications during the transplant and those that emerge during and after myelosuppression therapy. The literature emphasizes advanced periodontal disease, which is a chronic infectious condition that must be avoided or controlled during BMT, particularly because of the presence of S. viridans. The risk factors for oral mucositis, graft-versus-host disease (GVHD) and xerostomia have not yet been defined, particularly for oral mucositis and GVHD. Promising alternatives in the treatment of oral mucositis, including cryotherapy, administration of growth factors and laser therapy, are emphatically mentioned. In children, craniofacial and dental alterations, particularly resulting from radiotherapy are relevant. The increased risk of caries is controversial, and among fungal and viral lesions, oral and oropharyngeal infections by Candida and the herpes virus are identified as being of considerable clinical importance

    Relationship of arterial and exhaled CO2 during elevated artificial pneumoperitoneum pressure for introduction of the first trocar.

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    The present study evaluated the correlation between arterial CO2 and exhaled CO2 during brief high-pressure pneumoperitoneum. Patients were randomly distributed into two groups: P12 group (n=30) received a maximum intraperitoneal pressure of 12mmHg, and P20 group (n=37) received a maximum intraperitoneal pressure of 20mmHg. Arterial CO2 was evaluated by radial arterial catheter and exhaled CO2 was measured by capnometry at the following time points: before insufflation, once intraperitoneal pressure reached 12mmHg , 5 minutes after intraperitoneal pressure reached 12mmHg for the P12 group or 20mmHg for the P20 group, and 10 minutes after intraperitoneal pressure reached 12mmHg for the P12 group or when intraperitoneal pressure had decreased from 20mmHg to 12mmHg, for the P20 group. During brief durations of very high intraperitoneal pressure (20mmHg), there was a strong correlation between arterial CO2 and exhaled CO2. Capnometry can be effectively used to monitor patients during transient increases in artificial pneumoperitoneum pressure

    Invasive monitoring of the clinical effects of high intra-abdominal pressure for insertion of the first trocar.

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    Background: To analyze the effects of transitory, high intra-abdominal pressure on clinical, hemodynamic, blood gas and metabolic parameters.

Methods: Sixty-seven laparoscopic patients were divided into groups P12 (n = 30, maximum intra-abdominal pressure of 12 mmHg) and P20 (n = 37, maximum intra-abdominal pressure of 20 mmHg). Through radial artery cannulation, mean arterial pressure (MAP) was assessed and blood gas analysis – pH, arterial oxygen tension (PaO2), arterial carbon dioxide tension (PaCO2), bicarbonate (HCO3) and base excess (BE) – was performed. These parameters were evaluated in both groups at time point zero, before CO2 insufflation; at time point one (TP1), when intra-abdominal pressure of 12 mmHg was reached in both groups; at time point two (TP2), 5 minutes after reaching intra-abdominal pressure of 12 mmHg in group P12 and of 20 mmHg in group P20; and at time point three (TP3), 10 minutes after reaching intra-abdominal pressure of 12 mmHg in group P12 and 10 minutes after TP1 in group P20, when intra-abdominal pressure decreased from 20 mmHg to 12 mmHg. Values out of the normal range or the occurrence of atypical phenomena suggestive of organic disease indicated clinical changes.

Results: Significant variations in MAP, pH, HCO3 and BE were observed in group P20; these changes, however, were within normal limits. Clinical changes were also within normal limits, and no pathological phenomena were observed.

Conclusions: Brief, intra-abdominal hypertension for the insertion first trocar insertion causes variations in MAP, pH, HCO3 and BE without adverse effects, and it may protect from iatrogenic injury

    Rejeição e efeitos da ciclosporina nos transplantes cutâneos alógenos microcirúrgicos em ratos

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    Os efeitos da rejeição e da imunossupressão com ciclosporina A em retalhos epigástricos utilizados como transplantes cutâneos alógenos microcirúrgicos, foram estudados em 58 ratos, distribuídos em três grupos: Wistar-Furth isogênicos doadores e receptores; e Brown-Norway doadores e Wistar-Furth receptores, imunossuprimidos com cicloporina A(10mg/kg/dia). Biópsias dos retalhos e da pele normal contralateral utilizadas como contrôle foram colhidas no terceiro, sétimo, 15º e 30º dias pós transplante. As biópsias foram preparadas em historesina, e coradas em azul de toluidina, para avaliação do infiltrado inflamatório local, permitindo estudo quantitativo dos linfócitos infiltrantes nos retalhos. O modelo revelou-se eficiente, obtendo-se sobrevivência dos transplantes por 30 dias, de 83,3% entre animais isogênicos, e de 60% nos alogênicos sob ação da ciclosporina A. Em ratos alogênicos não imunossuprimidos houve 100% de rejeição dos retalhos, até o nono dia pós-operatório. Nos transplantes desses animais, verificou-se aumento significativo do número de linfócitos infiltrantes no terceiro dia, quando comparados aos ratos isogênicos. A linfocitose observada antecedeu os achados macroscópicos da rejeição, verificados apenas no quinto ou sexto dias.The rejection of allotransplantation of epigastric microsurgical flaps and the effect of immunosuppression have been studied in 58 rats. Three sets of experiments were planned: (1) Wistar Furth isogenic donors and receptors (control set); (2) Brown Norway donors and Wistar Furth receptors (rejection set); and (3) Brown Norway donors and Wistar Furth immunosuppressed receptors (cyclosporin A set). Cyclosporin A (10 mg/kg/d) treated rats had a transplantation survival rate of up to 30 days: 83.3% among isogenic animals and 60% among allogeneic. There was 100% rejection by the 9th day after the transplantation in allogeneic non-immunosuppressed rats. Biopsies embedded with historesin were taken from the flap and normal contralateral skin (used as control) on the 3rd, 7th, 15th, and 30th days after the surgery. A quantitative study of infiltrating lymphocytes in the flaps, with and without cyclosporin A, was done by evaluating the local inflammatory infiltrate. A significant increase in the number of lymphocytes among the rejection and immunosuppressed groups was seen, as compared to the isogenic set. Local lymphocytosis in allogeneic non-immunosuppressed transplantations reached its highest level on the 3rd day after surgery, before gross findings of rejection, which could only be seen by naked eye on the 5th or 6th day. Therefore, we conclude that cyclosporin A is effective in preserving allogenic transplantation in rats. Biopsies of transplanted areas may contribute to earlier diagnosis of the need for immunosuppressive therapy
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