Bounds on policy relevant parameters with discrete policy variation

When estimating policy parameters, also known as treatment effects, the assignment to treatment mechanism almost always causes endogeneity and thus bias many of these policy parameters estimates. Additionally, heterogeneity in program impacts is more likely to be the norm than the exception for most social programs. In situations where these issues are present, the Marginal Treatment Effect (MTE) parameter estimation makes use of an instrument to avoid assignment bias and simultaneously to account for heterogeneous effects throughout individuals. Although this parameter is point identified in the literature, the assumptions required for identification may be strong. Given that, we use weaker assumptions in order to partially identify the MTE, i.e. to stablish a methodology for MTE bounds estimation, implementing it computationally and showing results from Monte Carlo simulations. The partial identification we perfom requires the MTE to be a monotone function over the propensity score, which is a reasonable assumption on several economics' examples, and the simulation results shows it is possible to get informative even in restricted cases where point identification is lost. Additionally, in situations where estimated bounds are not informative and the traditional point identification is lost, we suggest a more generic method to point estimate MTE using the Moore-Penrose Pseudo-Invese Matrix, achieving better results than traditional methods.

The impact of negative social environmental events on the market value of supply chain partners

The present work analyzes the impact of negative social / environmental events on the market value of supply chain partners. The study offers a contextualized discussion around important concepts which are largely employed on the Operations Management and Management literature in general. Among them, the developments of the literature around supply chains, supply chain management, corporate social responsibility, sustainable development and sustainable supply chain management are particularly addressed, beyond the links they share with competitive advantage. As for the theoretical bases, the study rests on the Stakeholder Theory, on the discussion of the efficient-market hypothesis and on the discussion of the adjustment of stock prices to new information. In face of such literature review negative social / environmental events are then hypothesized as causing negative impact in the market value of supply chain partners. Through the documental analysis of publicly available information around 15 different cases (i.e. 15 events), 82 supply chain partners were identified. Event studies for seven different event windows were conducted on the variation of the stock price of each supply chain partner, valuing the market reaction to the stock price of a firm due to triggering events occurred in another. The results show that, in general, the market value of supply chain partners was not penalized in response to such announcements. In that sense, the hypothesis derived from the literature review is not confirmed. Beyond that, the study also provides a critical description of the 15 cases, identifying the companies that have originated such events and their supply chain partners involved.

Stochastic discount factor bounds and rare events: a review

We aim to provide a review of the stochastic discount factor bounds usually applied to diagnose asset pricing models. In particular, we mainly discuss the bounds used to analyze the disaster model of Barro (2006). Our attention is focused in this disaster model since the stochastic discount factor bounds that are applied to study the performance of disaster models usually consider the approach of Barro (2006). We first present the entropy bounds that provide a diagnosis of the analyzed disaster model which are the methods of Almeida and Garcia (2012, 2016); Ghosh et al. (2016). Then, we discuss how their results according to the disaster model are related to each other and also present the findings of other methodologies that are similar to these bounds but provide different evidence about the performance of the framework developed by Barro (2006).

Benthic response to upwelling events off the SE Brazilian coast

The main aim of the present study was to evaluate and compare temporal responses of the benthos in 2 continental shelf areas (Cabo Frio and Ubatuba) off the SE Brazilian coast. In Cabo Frio (23 degrees S, 42 degrees W), the western boundary coastal upwelling of the South Atlantic Central Water (SACW) enhances primary productivity, potentially increasing food supply to the benthic communities via sinking of particulate organic carbon (POC). In contrast, POC fluxes in Ubatuba (23 degrees S, 45 degrees W) are expected to be comparatively lower because SACW remains subsurface. We analyzed the temporal and spatial input of phytodetritus (concentration of chlorophyll a in sediments) and the benthic microbial biomass (estimated by ATP-based carbon content in sediments). Median surface chlorophyll concentration was computed for all daily available SeaWiFS images (from 2001 and 2002) to follow chlorophyll a inputs. All parameters used to investigate benthic responses in the study areas showed consistently higher values in Cabo Frio than in Ubatuba. The results showed that benthic response to upwelling may last months, fueling the microbial communities in the Cabo Frio region.

Sparse 1D discrete Dirac operators I: Quantum transport

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Sparse one-dimensional discrete Dirac operators II: Spectral properties

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A modified Primal-Dual Logarithmic-Barrier Method for solving the Optimal Power Flow problem with discrete and continuous control variables

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Continuous-time and discrete-time sliding mode control accomplished using a computer

A computer-based sliding mode control (SMC) is analysed. The control law is accomplished using a computer and A/D and D/A converters. Two SMC designs are presented. The first one is a continuous-time conventional SMC design, with a variable structure law, which does not take into consideration the sampling period. The second one is a discrete-time SMC design, with a smooth sliding law, which does not have a structure variable and takes into consideration the sampling period. Both techniques are applied to control an inverted pendulum system. The performance of both the continuous-time and discrete-time controllers are compared. Simulations and experimental results are shown and the effectiveness of the proposed techniques is analysed.

Detection and classification of voltage disturbances using a Fuzzy-ARTMAP-wavelet network

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Dynamic Tracking with Zero Variation and Disturbance Rejection Applied to Discrete-Time Systems

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Prognostic factors for perioperative pulmonary events among patients undergoing upper abdominal surgery

CONTEXTO E OBJETIVO: Associações significativas entre cirurgia do abdome superior e eventos pulmonares do período perioperatório foram investigadas em pacientes com condições pulmonares pré-operatórias submetidos a anestesia geral. TIPO DE ESTUDO E LOCAL: Estudo retrospectivo cujos dados foram retirados de banco de dados obtidos prospectivamente de forma protocolada, de 1 de janeiro de 1999 a 31 de dezembro de 2004, em hospital universitário terciário. MÉTODOS: Estudados 3107 pacientes com mais de 11 anos, American Society of Anesthesiologists (ASA) I, II, III, com cirurgia de abdome superior sob anestesia geral, enviados à sala de recuperação. Condições pré-operatórias analisadas por regressão logística foram: idade, sexo, estado físico ASA, insuficiência cardíaca congestiva, asma, doença pulmonar obstrutiva crônica, insuficiência respiratória e hábito de fumar. Os resultados estudados, ou variáveis dependentes, incluíram eventos intra- e pós-operatórios: broncoespasmo, hipoxemia, hipercapnia, intubação prolongada e secreção de vias aéreas. RESULTADOS: Dos 3.107 pacientes: 1.540 eram homens, 1.649 mulheres, tinham média de 48 anos, 1088 ASA I, 1402 ASA II, 617 ASA III, com insuficiência cardíaca havia 80, asma, 82, doença pulmonar obstrutiva, 122, insuficiência respiratória, 21, hábito de fumar, 428. Pela regressão logística, sexo feminino (p < 0.001), idade maior que 70 anos (p < 0.01), hábito de fumar (p < 0.001) e doença pulmonar obstrutiva crônica (p < 0.02) influenciaram significativamente o desenvolvimento de eventos pulmonares, principalmente hipoxemia e broncospasmo, em ambos os períodos, mas não nos mesmos pacientes. Asma e insuficiência cardíaca não se associaram com eventos pulmonares na sala de recuperação. CONCLUSÃO: em cirurgia do abdome superior sob anestesia geral, sexo feminino, idade maior que 70 anos, hábito de fumar e doença pulmonar obstrutiva crônica foram fatores de risco independentes para a ocorrência de eventos pulmonares intra- e pós-operatórios.

Association between atherosclerotic aortic plaques and left ventricular hypertrophy in patients with cerebrovascular events

Background and Purpose - the purpose of this research was to evaluate whether an association exists between the presence of atherosclerotic plaque in the thoracic aorta and left ventricular hypertrophy (LVH) in patients with a cerebrovascular event.Methods - We included 116 consecutive patients ( 79 men; mean age, 62 +/- 12.4 years) with previous history of stroke or transient ischemic attack in a cross-sectional study. Transthoracic echocardiogram was performed to diagnose LVH and transesophageal echocardiogram for the detection of atheromas of the thoracic aorta. Continuous variables were analyzed by Student t or Mann-Whitney tests and categorized variables by Goodman test. From the significant association of LVH and age with atheromatous disease of the aorta, an adjustment to the multivariate logistic model was made using high blood pressure history or age as covariates. All of the statistical tests were carried out at a level of 5% significance.Results - Almost half of the patients (43.1%) presented atherosclerotic lesions in the aorta. LVH was present in 90.0% of patients with plaque and in only 30.3% of patients without plaque. Using high blood pressure as a covariate, the risk of patients with LVH presenting atherosclerotic plaque in the aorta was 18.23-fold greater than the risk for patients without LVH (95% CI, 5.68 to 58.54; P < 0.0001). Adding age into the model, the risk increased to 26.36 ( 95% CI, 7.14 to 97.30; P < 0.0001).Conclusions - LVH detected by conventional echocardiogram is associated with high risk of atherosclerotic plaque in the aorta and would be used as a criterion for indication of transesophageal echocardiography in patients with previous stroke or transient ischemic attack LVH.

Association between distressing non-work-related events and occupational injuries

The following is a report on a case-control study whose objective was to investigate the association between distressing non-work-related events and occupational injures. Ninety three injured workers (cases) were matched with 372 non-injured controls in a large metallurgical factory in southeastern Brazil. Exposure to distressing non-work-related events was measured through a questionnaire focusing on situations pertaining to personal problems unrelated to work activities. The data were analyzed by adjusting a conditional logistic regression model, where occurrence of the work injury was the dependent dichotomous variable and answers from the questionnaire were independent continuous variables. The analysis showed an association between some distressing non-work-related events and occupational injuries. These findings imply expanding the horizon of preventive measures used in targeting. work injuries which have traditionally been focused on the control of strictly workplace risks.

Likelihood approximations and discrete models for tied survival data

Ties among event times are often recorded in survival studies. For example, in a two week laboratory study where event times are measured in days, ties are very likely to occur. The proportional hazards model might be used in this setting using an approximated partial likelihood function. This approximation works well when the number of ties is small. on the other hand, discrete regression models are suggested when the data are heavily tied. However, in many situations it is not clear which approach should be used in practice. In this work, empirical guidelines based on Monte Carlo simulations are provided. These recommendations are based on a measure of the amount of tied data present and the mean square error. An example illustrates the proposed criterion.