Is neglected heterogeneity really an issue in binary and fractional regression models? A simulation exercise for logit, probit and loglog models

In this paper we examine theoretically and by simulation whether or not unobserved heterogeneity independent of the included regressors is really an issue in logit, probit and loglog models with both binary and fractional data. We found that unobserved heterogeneity: (i) produces an attenuation bias in the estimation of regression coefficients; (ii) is innocuous for logit estimation of average sample partial effects, while in the probit and loglog cases there may be important biases in the estimation of those quantities; (iii) has much more destructive effects over the estimation of population partial effects; (iv) only for logit models does not affect substantially the prediction of outcomes; and (v) is innocuous for the size and consistency of Wald tests for the significance of observed regressors but, in small samples, reduces their power substantially.Binary models; fractional models; neglected heterogeneity; partial effects; prediction; wald tests.

Selective Use of Pericardial Window and Drainage as Sole Treatment for Hemopericardium from Penetrating Chest Trauma

Background Penetrating cardiac injuries (PCIs) are highly lethal, and a sternotomy is considered mandatory for suspected PCI. Recent literature suggests pericardial window (PCW) may be sufficient for superficial cardiac injuries to drain hemopericardium and assess for continued bleeding and instability. This study objective is to review patients with PCI managed with sternotomy and PCW and compare outcomes. Methods All patients with penetrating chest trauma from 2000 to 2016 requiring PCW or sternotomy were reviewed. Data were collected for patients who had PCW for hemopericardium managed with only pericardial drain, or underwent sternotomy for cardiac injuries grade 1–3 according to the American Association for the Surgery of Trauma (AAST) Cardiac Organ Injury Scale (OIS). The PCW+drain group was compared with the Sternotomy group using Fisher’s exact and Wilcoxon rank-sum test with P\u3c0.05 considered statistically significant. Results Sternotomy was performed in 57 patients for suspected PCI, including 7 with AAST OIS grade 1–3 injuries (Sternotomy group). Four patients had pericardial injuries, three had partial thickness cardiac injuries, two of which were suture-repaired. Average blood drained was 285mL (100–500 mL). PCW was performed in 37 patients, and 21 had hemopericardium; 16 patients proceeded to sternotomy and 5 were treated with pericardial drainage (PCW+drain group). All PCW+drain patients had suction evacuation of hemopericardium, pericardial lavage, and verified bleeding cessation, followed by pericardial drain placement and admission to intensive care unit (ICU). Average blood drained was 240mL (40–600 mL), and pericardial drains were removed on postoperative day 3.6 (2–5). There was no significant difference in demographics, injury mechanism, Revised Trauma Score exploratory laparotomies, hospital or ICU length of stay, or ventilator days. No in-hospital mortality occurred in either group. Conclusions Hemodynamically stable patients with penetrating chest trauma and hemopericardium may be safely managed with PCW, lavage and drainage with documented cessation of bleeding, and postoperative ICU monitoring. Level of evidence Therapeutic study, level IV

Moment-based estimation of nonlinear regression models with boundary outcomes and endogeneity, with applications to nonnegative and fractional responses

In this article, we suggest simple moment-based estimators to deal with unobserved heterogeneity in a special class of nonlinear regression models that includes as main particular cases exponential models for nonnegative responses and logit and complementary loglog models for fractional responses. The proposed estimators: (i) treat observed and omitted covariates in a similar manner; (ii) can deal with boundary outcomes; (iii) accommodate endogenous explanatory variables without requiring knowledge on the reduced form model, although such information may be easily incorporated in the estimation process; (iv) do not require distributional assumptions on the unobservables, a conditional mean assumption being enough forconsistentestimationofthestructuralparameters;and(v)undertheadditionalassumption that the dependence between observables and unobservables is restricted to the conditional mean, produce consistent estimators of partial effects conditional only on observables.info:eu-repo/semantics/publishedVersio

Combining micro and macro data in hedonic price indexes

This paper proposes arithmetic and geometric Paasche quality-adjusted price indexes that combine micro data from the base period with macro data on the averages of asset prices and characteristics at the index period. The suggested indexes have two types of advantages relative to traditional Paasche indexes: (i) simplification and cost reduction of data acquisition and manipulation; and (ii) potentially greater efficiency and robustness to sampling problems. A Monte Carlo simulation study and an empirical application concerning the housing market illustrate some of those advantages.info:eu-repo/semantics/publishedVersio

Assisted attenuation of a soil contaminated by diuron using hydroxypropyl-β-cyclodextrin and organic amendments

7 páginas.-- 1 Grafico.-- 3 figuras.-- 2 tablas.-- 59 referenciasDiuron desorption and mineralisation were studied on an amended and artificially contaminated soil. The amendments used comprised two different composted organic residues i.e., sewage sludge (SS) mixed with pruning wastes, and urban solid residues (USR), and two different solutions (with inorganic salts as the micronutrients and hydroxypropyl-β-cyclodextrin (HPBCD)). After applying micronutrients to activate the soil flora, 15.5% mineralisation could be reached after 150 days, indicating that the soil has a potential capacity to mineralise the herbicide through biostimulation-assisted attenuation. Diuron mineralisation was also improved when HPBCD solutions were applied. Indeed, the extent of herbicide mineralisation reached 29.7% with this application. Moreover, both the lag phase and the half-life time (DT50) were reduced to 33 and 1778 days, respectively, relative to the application of just micronutrients (i.e., 39 and 6297 days, respectively). Organic amendments were also applied (i.e., USR and SS) on the contaminated soil: it was found that the diuron mineralisation rate was improved as the amendment concentration increased. The joint application of all treatments investigated at the best conditions tested was conducted to obtain the best diuron mineralisation results. The micronutrient amendment plus 4% USR or SS amendment plus HPBCD solution (10-fold diuron initially spiked) caused an extent of diuron mineralisation 33.2 or 46.5%, respectively.This work was supported by the Spanish Ministry of Science and Innovation (co-funded by the Fondo Europeo de Desarrollo Regional, FEDER) under the research project CTM2009-07335 and Junta de Andalucía (RNM 894).Peer reviewe

Oferta formativa na área de Gestão Hoteleira e sua articulação com o mercado de emprego nas empresas hoteleiras da Região Autónoma da Madeira

Desde há largos anos que o turismo se afirma em lugares de liderança no suporte e crescimento da economia na região insular da Madeira e Porto Santo, promovendo um sistema de relações com forte impacto em diversas áreas industriais, de transportes, de lazer e académicas. A hotelaria assume um lugar destacado na oferta e promoção turística, suportando pacotes de produtos e atributos do destino que cativam os turistas essencialmente pela qualidade dos serviços promovida pelos colaboradores, orientados pelo centro dinamizador da criação, organização,avaliação, promoção e liderança dos serviços hoteleiros, presente na sua gestão e no desempenho do Gestor Hoteleiro. Este trabalho surge orientado para uma pesquisa movida pelo interesse em procurar conhecer o nível de informação dos empresários acerca da capacidade atual da oferta formativa em Gestão Hoteleira na Região Autónoma da Madeira, orientado pelo objetivo de analisar a relação e os mecanismos atuais entre as entidades de ensino superior e as empresas, com influência no grau de empregabilidade, enquanto fenómeno com indiscutível impacto na economia e na sociedade local. No estudo adotou-se uma metodologia quantitativa com uma complementaridade qualitativa, que permitem uma reflexão ampla e atualizada acerca dos problemas da empregabilidade qualificada e dos seus constrangimentos. A tradicional solução por gestores com valor, muitas vezes suportados numa aprendizagem empírica, deve merecer alguma atenção das empresas, nomeadamente pela crescente introdução de tecnologia de informação comunicação, com relevo para as plataformas digitais, num universo de permanente inovação e reorganização, normalmente fruto da pressão e feroz concorrência. O principal contributo que este estudo pretende, assenta na promoção de uma reflexão entre todas as entidades administrativas, formativas e as empresas, procurando benefícios bilaterais e uma adequada sustentabilidade social, económica e ambiental

Eficácia da oxamniquine, do praziquantel e da combinação de ambas as drogas na esquistossomose mansônica no Brasil

Conduziu-se um ensaio clínico para comparar a eficácia de uma combinação em baixas doses de oxamniquine (7,5 mg/kg) mais praziquantel (20 mg/kg) com ambas as drogas - oxamniquine (15 mg/kg) e praziquantel (40 mg/kg) - empregadas isoladamente, no tratamento da esquistossomose mansônica em uma área endêmica do nordeste brasileiro. Os medicamentos foram administrados, aleatoriamente, por via oral, a 91 pacientes. Seis e doze meses depois do tratamento 89% dos admitidos no ensaio foram reexaminados segundo os métodos de Kato-Katz (dez lâminas) e MIF (um grama de fezes). Os índices de cura alcançados, representando a ausência de ovos nas fezes em todos os controles durante o acompanhamento parasitológico individualizado dos pacientes, foram de 81,8%, 81,2% e 67,6% com, respectivamente, o praziquantel, a oxamniquine e a combinação. A redução do número de ovos eliminado por gra ma de fezes nos casos não curados, variou de 93,8 96,8% com o praziquantel, 32,5 97% com a oxamniquine e 76,9-99,5% com a combinação. Concluiu-se que os três regimes terapêuticos, nas doses utilizadas, dão resultados similares e satisfatórios no tratamento da esquistossomose mansônica não complicada, no Brasil.A randomized clinical trial was carried out to compare the efficacy of a low-dosage combination of oxamniquine (7.5 mg/kg) plus praziquantel (20 mg/kg) against either agent, oxamniquine (15 mg/kg) or praziquantel (40 mg/kg) alone, in the treatment of schistosomiasis mansoni in the Brazilian north-east. The drugs were randomly administered per os to 91 patients. Six and twelve months after treatment 89% of those admitted to the trial were reexamined by Kato-Katz method (ten slides) and MIF technique (one gram of stool) The achieved cure rates, as defined by absence of S. mansoni eggs in the faeces of individual patients at all points during the parasitological follow-up, were 81.8%, 81.2% and 67.6% for praziquantel, oxamniquine and the combination respectively. The reduction of eggs excretion in non cured patients six months after therapy ranged from 93.8-96.8% with praziquantel, 32.5-97% with oxamniquine and 76.9-99.5% with the combination. It is concluded that, at the used dosages, the three therapeutical regimens give similar and satisfactory results in the treatment of uncomplicated S. mansoni infection in Brazil

Comparative effects of several cyclodextrins on the extraction of PAHs from an aged contaminated soil

7 páginas.-- 3 figuras.-- 2 tablas.-- 52 referencias.-- Supplementary dataThe objective of the present study was to characterise the polycyclic aromatic hydrocarbons (PAHs) content of an aged contaminated soil and to propose remediation techniques using cyclodextrins (CDs). Four CDs solutions were tested as soil decontamination tool and proved more efficient in extracting PAHs than when an aqueous solution was used; especially two chemically modified CDs resulted in higher extraction percentages than natural β-CD. The highest extraction percentages were obtained for 3-ring PAHs, because of the appropriate size and shape of these compounds relative to those of the hydrophobic cavities of the CDs studied. A detailed mechanistic interpretation of the chemical modification of CDs on the extraction of the different PAHs has been performed, and connected with the role that the different hydrophobicities of the PAHs play in the extraction behaviour observed for the 16 PAHs, limiting their accessibility and the remaining risk of those PAHs not extractable by CDs. © 2013 Elsevier Ltd. All rights reserved.The authors thank to Dr. J.R. Gallego from the Universidad de Oviedo for providing the contaminated soil sample. Support from projects CTM2006-04626 and CTM2009-07335, Spanish Ministry of Science and Innovation (co-funded by Fondo Europeo de Desarrollo Regional, FEDER), are greatly appreciated. M.A. Sánchez-Trujillo acknowledges a research contract from CSIC (JAEPre 0800763) cofinanced by Fondo Social Europeo (FSE).Peer Reviewe

Effects of soil characteristics on metribuzin dissipation using clay-gel-based formulations

Metribuzin (MTB) is a herbicide widely used for weed control in growing soybeans and other crops and has been identified in many parts of the world as a groundwater contaminant. To prepare controlled-release formulations (CRFs) of MTB, it was entrapped within a sepiolite-gel-based matrix with one of two proportions of clay/herbicide and used as either a gel or powder after freeze-drying. To determine how its persistence in soil is affected by formulation and soil type, MTB was applied as a CRF or commercial formulation (CM) to soils with different properties. MTB dissipation in all soils investigated was reduced when the herbicide was applied as CRFs, especially in the case of sandy soil and the freeze-dried formulations, with DT50 values of 57.5 and 104.1 days, respectively, versus 24.8 days for CM. A positive relationship between degradation rates, bioactivity, and soil pH was found. MTB adsorption-desorption studies on these soils were also performed, and no relationship between adsorption-desorption and the degradation rate of MTB was found, possibly because of the low adsorption capacity of the studied soils. MTB when applied as a CRF remains active longer than CM, avoiding the need to use more frequently herbicide applications.This work was supported by the Spanish Ministry of Education and Science (MEC) through Research Projects AGL 2005-00164, by Junta de Andaluc ́ıa (project P06-FQM-01909), and by AECID (project A/016047/08).Peer Reviewe