883 resultados para Input filtering
Resumo:
This paper considers a stochastic frontier production function which has additive, heteroscedastic error structure. The model allows for negative or positive marginal production risks of inputs, as originally proposed by Just and Pope (1978). The technical efficiencies of individual firms in the sample are a function of the levels of the input variables in the stochastic frontier, in addition to the technical inefficiency effects. These are two features of the model which are not exhibited by the commonly used stochastic frontiers with multiplicative error structures, An empirical application is presented using cross-sectional data on Ethiopian peasant farmers. The null hypothesis of no technical inefficiencies of production among these farmers is accepted. Further, the flexible risk models do not fit the data on peasant farmers as well as the traditional stochastic frontier model with multiplicative error structure.
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Low-grade inflammation adversely influences metabolism and cardiovascular prognosis, nevertheless increased intake of fruits and vegetables has rarely been studied in this context. Objective: In a prospective controlled study, the effect on C-reactive protein (CRP) levels was assessed. Methodology: Sixty consecutive women undergoing cosmetic abdominal surgery were instructed to consume six servings each of fruits and vegetables during the first postoperative month. Detailed 24h interviewer-administered dietary recall was conducted at baseline and at the end of the study, with weekly returns to monitor unscheduled dietary changes and compliance with the protocol. Variance (ANOVA) and covariance (ANCOVA) were evaluated to confirm significance and minimize confounding variables. Results: No differences concerning age (42.2 +/- 5.3 vs 41.1 +/- 6.0 years) or BMI (25.5 +/- 3.1 vs 25.0 +/- 3.0 kg/m(2)) occurred. Ingestion of fruits increased to approximately 5.2 vs 3.9 and of vegetables 5.9 vs 3.4 servings/ day, respectively. CRP decreased more conspicuously in the treated group (P = 0.028), and correlation between vitamin C input and CRP in supplemented participants was demonstrated (P = 0.014). Conclusions: Higher intake of antioxidant foods was feasible, and an antiinflammaotory effect occurred. Further studies with longer administration and follow-up period are recommended.
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We examine subnatural phase-dependent linewidths in the fluorescence spectrum of a three-level atom damped by a narrow-bandwidth squeezed vacuum in a cavity. Using the dressed-atom model approach of a strongly driven three-level cascade system, we derive the master equation of the system from which we obtain simple analytical expressions for the fluorescence spectrum. We show that the phase effects depend on the bandwidths of the squeezed vacuum and the cavity relative to the Rabi frequency of the driving fields. When the squeezing bandwidth is much larger than the Rabi frequency, the spectrum consists of five lines with only the central and outer sidebands dependent on the phase. For a squeezing bandwidth much smaller than the Rabi frequency the number of lines in the spectrum and their phase properties depend on the frequency at which the squeezing and cavity modes are centered. When the squeezing and cavity modes are centered on the inner Rabi sidebands, the spectrum exhibits five lines that are completely independent of the squeezing phase with only the inner Rabi sidebands dependent on the squeezing correlations. Matching the squeezing and cavity modes to the outer Rabi sidebands leads to the disappearance of the inner Rabi sidebands and a strong phase dependence of the central line and the outer Rabi sidebands. We find that in this case the system behaves as an individual two-level system that reveals exactly the noise distribution in the input squeezed vacuum. [S1050-2947(97)00111-X].
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The aim of this study was to investigate the effect of supplementation of vitamin E, vitamin C, and zinc on the oxidative stress in burned children. In a prospective double-blind placebo-controlled pilot study, 32 patients were randomized as no supplementation (n = 15) or antioxidant supplementation (n = 17) groups. Supplementation consisted of the antioxidant mixture of vitamin C (1.5 times upper intake level), vitamin E (1.35 times upper intake level), and zinc (2.0 times recommended dietary allowance) administered during 7 days starting on the second day of admittance into the hospital. Energy requirement was calculated by the Curreri equation, and protein input was 3.0 g/kg of ideal body mass index (percentile 50 degrees). Total antioxidant capacity of plasma and malondialdehyde were used to monitor oxidative stress. The time of wound healing was evaluated as the main clinical feature. Patients (age 54.2 +/- 48.9 months, 65.6% males), who exhibited 15.5 +/- 6.7% of total burn area, showed no differences in age and sex, when compared with controls. Intake of the administered antioxidants was obviously higher in treated subjects (P = .005), and serum differences were confirmed for vitamin E and C, but not for zinc (P = .180). There was a decrease in lipid peroxidation (malondialdehyde level) (P = .006) and an increase in vitamin E concentrations in the antioxidant supplementation group (P = .016). The time of wound healing was lower in the supplemented group (P < .001). The antioxidant supplementation through vitamin E and C and the mineral zinc apparently enhanced antioxidant protection against oxidative stress and allowed less time for wound healing. (J Burn Care Res 2009;30:859-866)
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Fuzzy Bayesian tests were performed to evaluate whether the mother`s seroprevalence and children`s seroconversion to measles vaccine could be considered as ""high"" or ""low"". The results of the tests were aggregated into a fuzzy rule-based model structure, which would allow an expert to influence the model results. The linguistic model was developed considering four input variables. As the model output, we obtain the recommended age-specific vaccine coverage. The inputs of the fuzzy rules are fuzzy sets and the outputs are constant functions, performing the simplest Takagi-Sugeno-Kang model. This fuzzy approach is compared to a classical one, where the classical Bayes test was performed. Although the fuzzy and classical performances were similar, the fuzzy approach was more detailed and revealed important differences. In addition to taking into account subjective information in the form of fuzzy hypotheses it can be intuitively grasped by the decision maker. Finally, we show that the Bayesian test of fuzzy hypotheses is an interesting approach from the theoretical point of view, in the sense that it combines two complementary areas of investigation, normally seen as competitive. (C) 2007 IMACS. Published by Elsevier B.V. All rights reserved.
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Objective: High levels of domestic violence, mental illness, and alienation from authorities are associated with high incidence of children/adolescents living on the streets in low and middle income countries. The Equilibrium Project (Programa Equilibrio) was created to facilitate social reintegration through a virtual partnership between an academic psychiatric institute and highly vulnerable children and adolescents living on the streets, in group shelter with supervision, and in other high risk situations. Methods: Descriptive presentation of qualitative data and analysis of preliminary empirical data collected over a 24-month period. Results: Dialogue between academic professionals, street children, and city officials shaped The Equilibrium Project over the last 2 years. The program has progressively moved from a professional clinic setting to a community-based but protected activity center with recreational and professional services and an emphasis on linkage with social service agencies, city government and law enforcement officials in an academic research context. A total of 351 patients have been served of whom virtually all were neglected by their parents, 58.4% report physical or sexual abuse, 88.89% have been diagnosed with a psychiatric disorder, 40.4% drug use. After 2 years of operation, 63.5% (n = 223) successfully completed or continue in treatment and 34.8% (n = 122) were reunited with their families. Conclusions and Practice implications: Program development guided by consumer input led to a successful program offering professional services in a protected community setting that facilitates social reintegration by providing ""go between"" services integrating relationships between alienated consumers and formal psychiatric, pediatric, social service, and criminal justice systems. (C) 2011 Elsevier Ltd. All rights reserved.
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Objective: The aim of this article is to propose an integrated framework for extracting and describing patterns of disorders from medical images using a combination of linear discriminant analysis and active contour models. Methods: A multivariate statistical methodology was first used to identify the most discriminating hyperplane separating two groups of images (from healthy controls and patients with schizophrenia) contained in the input data. After this, the present work makes explicit the differences found by the multivariate statistical method by subtracting the discriminant models of controls and patients, weighted by the pooled variance between the two groups. A variational level-set technique was used to segment clusters of these differences. We obtain a label of each anatomical change using the Talairach atlas. Results: In this work all the data was analysed simultaneously rather than assuming a priori regions of interest. As a consequence of this, by using active contour models, we were able to obtain regions of interest that were emergent from the data. The results were evaluated using, as gold standard, well-known facts about the neuroanatomical changes related to schizophrenia. Most of the items in the gold standard was covered in our result set. Conclusions: We argue that such investigation provides a suitable framework for characterising the high complexity of magnetic resonance images in schizophrenia as the results obtained indicate a high sensitivity rate with respect to the gold standard. (C) 2010 Elsevier B.V. All rights reserved.
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Objective: We correlated dietary profile and markers of visceral and somatic obesities in nonalcoholic fatty liver disease. Methods: Patients with histologically proven fatty infiltration of the liver (n = 25, 52 +/- 11 y of age, 64% women) underwent abdominal computed tomography, bioelectrical impedance, and anthropometric measurements. Insulin resistance was evaluated (homeostasis model assessment) and dietary intake of macronutrients was estimated by 24-h recall. Main outcome measurements were correlation of carbohydrate and fat ingestion with liver histology. Results: Metabolic syndrome was present in 72% of the population, and increased waist circumference and low high-density lipoprotein cholesterol occurred in 66%. Total body fat (bioimpedance) and dietary intake of lipids were higher in patients with non-alcoholic steatohepatitis (P < 0.05), but not in diabetic subjects who exhibited more steatosis than non-alcoholic steatohepatitis. Waist circumference exhibited a good correlation with homeostasis model assessment, total energy intake, and ingestion of specific fatty acids. Body mass index correlated well with somatic and visceral adiposities. Conclusion: Energy intake and visceral adiposity were predisposing factors for fatty liver disease. Lipid input correlated with non-alcoholic steatohepatitis in the entire group and after stratification for diabetes. These findings suggest that lipid intake may play a greater role in non-alcoholic steatohepatitis than hitherto suspected. (C) 2008 Elsevier Inc. All rights reserved.
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Aim: To identify how the methodology of Reflection Groups (RG) can contribute to approach social-psychological problems, so often observed as obstacles in PE efforts. The objective was also to verify the contributions from RG to the implementation of ergonomics recommendations, which were a starting point and organized group discussions. Method: A concrete case was used as an illustration, and studied in depth: RG with administration and production workers` representatives from the Department of Nutrition and Dietetics of a cardiologic hospital in Sao Paulo, Brazil. RG are temporary thinking groups, taking place outside the workplace and having delegative and consultive participation. They make use of Operative Groups, an adapted form of tripartite group, activity as an instrumental resource, group dynamic techniques and videotaping. In 2007, 31 meetings took place during paid working hours with 7 groups of different composition, ranging from 1.5 h to 3 h. Results: Additionally to the positive effects in communication and psychosocial environment, RG could also contribute to changes in interpersonal relationships, cooperation, personal and work behaviours. By dealing with aspects which could hinder the explicit task: fears, conflicts, and stereotyped beliefs and behaviours; resistance to change could be broken and group members could learn. RG allowed input about new risks; continuous information and feedback about ongoing ergonomics interventions so that immediate corrective action could be taken. The main form of participation was in administrative, organizational, and psychosocial problems which required a better clarification and identification of their real causes, commitment, and elaboration of strategies and negotiation of different stakeholders in their solution. Conclusion: RG takes advantage of homogeneous and heterogeneous groups, in face to face communication. The interactions in the groups are task-oriented (explicit task) but attaining groups` goals depends on a relational interaction (implicit task). Relevance to industry: Reflection groups can bring important contributions to ergonomics and industry because they favour the discussion, disclosure of problems and incorporation of solutions, enabling interventions in working organization, psychosocial environment and relationships in a collective and participatory approach, promoting health and social integration. (C) 2010 Elsevier B.V. All rights reserved.
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This work characterizes the effects of ambient levels of urban particulate matter (PM(2.5)) from the city of Sao Paulo on spermatogenesis using mice exposed during the embryo-fetal and/or postnatal phases of development. Parental generations (BALB/c mice) were exposed to air pollution in chambers with or without filtering PM(2.5) for 4 months. Animals were mated, and half of the 1-day-old offspring were moved between chambers, which yielded prenatal and postnatal groups. Remaining offspring comprised the non-exposed and pre+postnatal exposed groups. After 90 days, the animals were sacrificed for testis collection and weighing. Optical microscopy was used for the morphometric analyses of the cell counts, spermatogenic cycle, proliferation, and apoptosis. Prenatally exposed animals presented reduced body and testicular weight with an increased gonadosomatic index (GSI). Testicular volume also decreased, as well as the tubular diameter in testes of the same animals. Proliferation, apoptosis, and spermatogenic cycle analyses showed no significant differences among groups. However, the tubules at stage VII of pre- and postnatal animals presented a reduced number of elongated spermatids. Pre+postnatal group presented higher spermatid head retention at stages VIII-XII. These results show that ambient levels of PM(2.5) from Sao Paulo city affect spermatogenesis by damaging sperm production.
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The present study evaluated the effectiveness of electrotactile tongue biofeedback (BrainPort (R)) as a sensory substitute for the vestibular apparatus in patients with bilateral vestibular loss (BVL) who did not have a good response to conventional vestibular rehabilitation (VR). Seven patients with BVL were trained to use the device. Stimulation on the surface of the tongue was created by a dynamic pattern of electrical pulses and the patient was able to adjust the intensity of stimulation and spatially centralize the stimulus on the electrode array. Patients were directed to continuously adjust head orientation and to maintain the stimulus pattern at the center of the array. Postural tasks that present progressive difficulties were given during the use of the device. Pre- and post-treatment distribution of the sensory organization test (SOT) composite score showed an average value of 38.3 +/- 8.7 and 59.9 +/- 11.3, respectively, indicating a statistically significant improvement (p = 0.01). Electrotactile tongue biofeedback significantly improved the postural control of the study group, even if they had not improved with conventional VR. The electrotactile tongue biofeedback system was able to supply additional information about head position with respect to gravitational vertical orientation in the absence of vestibular input, improving postural control. Patients with BVL can integrate electrotactile information in their postural control in order to improve stability after conventional VR. These results were obtained and verified not only by the subjective questionnaire but also by the SOT composite score. The limitations of the study are the small sample size and short duration of the follow-up. The current findings show that the sensory substitution mediated by electrotactile tongue biofeedback may contribute to the improved balance experienced by these patients compared to VR. (C) 2010 Elsevier Ireland Ltd. All rights reserved.
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We have previously reported that L-glutamate (L-glu) injected into the ventral portion of medial prefrontal cortex (vMPFC) of unanesthetized normotensive Wistar rats elicited cardiovascular responses. In the present study we investigated whether the spontaneously hypertensive rat (SHR) exhibit abnormal cardiovascular responses after L-glu microinjection in the vMPFC. Microinjections of L-glu (3, 9, 27, 81 or 150 nmol/200 nl) caused long-lasting dose-related depressor and bradycardiac responses in unanesthetized SHR (n = 6, each dose). Pressor and tachycardiac responses were evoked after the injection of 81 nmol of L-glu in the vMPFC of normotensive Wistar rats (n=6). Systemic pretreatment with the betal-adrenoceptor antagonist atenolol (1.5 mg/kg, i.v.) had no effect on L-glu cardiovascular responses evoked in the SHR (n=5). However, the treatment with the muscarinic antagonist homatropine methyl bromide (I mg/kg, i.v.) blocked the bradycardiac response to L-glu, without significant effects on depressor response evoked by L-glu in the SHR (n = 5). These results indicate that the bradycardiac response to the injection of L-glu injection in the vMPFC is due to activation of the parasympathetic system and not to inhibition of the cardiac sympathetic input. In conclusion, results indicate opposite cardiovascular responses when L-glu was microinjected in the vMPFC of unanesthetized SHR or normotensive. The bradycardiac response observed in the SHR was due to parasympathetic activation and was not affected by pharmacological blockade of the cardiac sympathetic output. (C) 2007 Elsevier B.V. All rights reserved.
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Electrical or chemical stimulation of the dorsal periaqueductal gray matter (DPAG) evokes escape, a defensive behavior that has been related to panic attacks. Injection of 5-HT(1A) or 5-HT(2A) receptor agonists into this midbrain area inhibits this response. It has been proposed that the impairment of 5-HT mechanisms controlling escape at the level of the DPAG may underlie the susceptibility to panic attacks that characterizes the panic disorder. In this study we evaluated the effects of the pharmacological manipulation of the dorsal raphe nucleus (DRN), which are the main source of 5-HT input to the DPAG, on the escape response evoked in rats by the intra-DPAG injection of the nitric oxide donor SIN-1. The results showed that DRN administration of the 5-HT(1A) receptor agonist 8-OH-DPAT which inhibits the activity of 5-HT neurons favored the expression of escape induced by SIN-1. Intra-DRN injection of the excitatory amino acid kainic acid or the 5-HT(1A) receptor antagonist WAY-100635 did not change escape expression. However, both compounds fully blocked the escape reaction generated by intra-DPAG injection of the excitatory amino acid D,L-homocysteic acid (DLH). Overall, the results indicate that 5-HT neurons in the DRN exert a bidirectional control upon escape behavior generated by the DPAG. Taking into account the effect of WAY-100635 on DLH-induced escape, they also strengthen the view that DRN 5-HT(1A) autoreceptors are under tonic inhibitory influence by 5-HT. (C) 2010 Elsevier B.V. All rights reserved.
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The lateral part of intermediate layer of superior colliculus (SCI) is a critical substrate for successful predation by rats. Hunting-evoked expression of the activity marker Fos is concentrated in SCI while prey capture in rats with NMDA lesions in SCI is impaired. Particularly affected are rapid orienting and stereotyped sequences of actions associated with predation of fast moving prey. Such deficits are consistent with the view that the deep layers of SC are important for sensory guidance of movement. Although much of the relevant evidence involves visual control of movement, less is known about movement guidance by somatosensory input from vibrissae. Indeed, our impression is that prey contact with whiskers is a likely stimulus to trigger predation. Moreover, SCI receives whisker and orofacial somatosensory information directly from trigeminal complex, and indirectly from zona incerta, parvicelular reticular formation and somatosensory barrel cortex. To better understand sensory guidance of predation by vibrissal information we investigated prey capture by rats after whisker removal and the role of superior colliculus (SC) by comparing Fos expression after hunting with and without whiskers. Rats were allowed to hunt cockroaches, after which their whiskers were removed. Two days later they were allowed to hunt cockroaches again. Without whiskers the rats were less able to retain the cockroaches after capture and less able to pursue them in the event of the cockroach escaping. The predatory behaviour of rats with re-grown whiskers returned to normal. In parallel, Fos expression in SCI induced by predation was significantly reduced in whiskerless animals. We conclude that whiskers contribute to the efficiency of rat prey capture and that the loss of vibrissal input to SCI, as reflected by reduced Fos expression, could play a critical role in predatory deficits of whiskerless rats. (C) 2011 IBRO. Published by Elsevier Ltd. All rights reserved.
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The present study provides a detailed description of morphological and hodological aspects of the glomerular nucleus in the weakly electric fish Gymnotus sp., and explores the evolutionary and functional implications flowing from this analysis. The glomerular nucleus of Gymnotus shows numerous morphological similarities with the glomerular nucleus of percomorph fish, although cytoarchitectonically simpler. In addition, congruence of the histochemical acetylcholinesterase (AChE) distribution with cytoarchitectonic data suggests that the glomerular nucleus, together with the ventromedial cell group of the medial subdivision of the preglomerular complex (PGm-vmc) rostrally, and the subglomerular nucleus (as identified by Maler et al. [1991] J Chem Neuroanat 4:1-38) caudally, may form a distinct longitudinally organized glomerular complex. Our results show that an important source of sensory afferents to the glomerular nucleus originates in the pretectal and electrosensorius nuclei. The glomerular nucleus in turn projects to the hypothalamus (inferior lobe and anterior hypothalamus), to the anterior tuberal nucleus, and to the medial region of the preglomerular nucleus (PGm). These data suggest that visual and electrosensory information reach the glomerular nucleus and are relayed to the hypothalamus and, via PGm, to the pallium. Such connections are similar to those of the glomerular nucleus in percomorphs and the posterior pretectal nucleus in osteoglossomorph, esocids, and salmonids, where they comprise one component of a visual processing pathway. In Gymnotiform fish, however, the pretectal region that projects to the glomerular nucleus is dominated by electrosensory input (visual input is minor), which is consistent with the dominant role of electroreception in these fish. J. Comp. Neurol. 519:1658-1676, 2011. (c) 2011 Wiley-Liss, Inc.