Variable Selection in Nonparametric Classification via Measurement Error Model Selection Likelihoods.

Using the relationships among ridge regression, LASSO estimation, and measurement error attenuation as motivation, a new measurement-error-model-based approach to variable selection is developed. After describing the approach in the familiar context of linear regression, we apply it to the problem of variable selection in nonparametric classification, resulting in a new kernel-based classifier with LASSO-like shrinkage and variable-selection properties. Finite-sample performance of the new classification method is studied via simulation and real data examples, and consistency of the method is studied theoretically. Supplementary materials for the paper are available online.

Characterizing ammonia emissions from swine farms in eastern North Carolina: part 1--conventional lagoon and spray technology for waste treatment.

Ammonia (NH3) fluxes from waste treatment lagoons and barns at two conventional swine farms in eastern North Carolina were measured. The waste treatment lagoon data were analyzed to elucidate the temporal (seasonal and diurnal) variability and to derive regression relationships between NH3 flux and lagoon temperature, pH and ammonium content of the lagoon, and the most relevant meteorological parameters. NH3 fluxes were measured at various sampling locations on the lagoons by a flowthrough dynamic chamber system interfaced to an environmentally controlled mobile laboratory. Two sets of open-path Fourier transform infrared (FTIR) spectrometers were also used to measure NH3 concentrations for estimating NH3 emissions from the animal housing units (barns) at the lagoon and spray technology (LST) sites. Two different types of ventilation systems were used at the two farms. Moore farm used fan ventilation, and Stokes farm used natural ventilation. The early fall and winter season intensive measurement campaigns were conducted during September 9 to October 11, 2002 (lagoon temperature ranged from 21.2 to 33.6 degrees C) and January 6 to February 2, 2003 (lagoon temperature ranged from 1.7 to 12 degrees C), respectively. Significant differences in seasonal NH3 fluxes from the waste treatment lagoons were found at both farms. Typical diurnal variation of NH3 flux with its maximum value in the afternoon was observed during both experimental periods. Exponentially increasing flux with increasing surface lagoon temperature was observed, and a linear regression relationship between logarithm of NH3 flux and lagoon surface temperature (T1) was obtained. Correlations between lagoon NH3 flux and chemical parameters, such as pH, total Kjeldahl nitrogen (TKN), and total ammoniacal nitrogen (TAN) were found to be statistically insignificant or weak. In addition to lagoon surface temperature, the difference (D) between air temperature and the lagoon surface temperature was also found to influence the NH3 flux, especially when D > 0 (i.e., air hotter than lagoon). This hot-air effect is included in the statistical-observational model obtained in this study, which was used further in the companion study (Part II), to compare the emissions from potential environmental superior technologies to evaluate the effectiveness of each technology.

Characterizing ammonia emissions from swine farms in eastern North Carolina: part 2--potential environmentally superior technologies for waste treatment.

The need for developing environmentally superior and sustainable solutions for managing the animal waste at commercial swine farms in eastern North Carolina has been recognized in recent years. Program OPEN (Odor, Pathogens, and Emissions of Nitrogen), funded by the North Carolina State University Animal and Poultry Waste Management Center (APWMC), was initiated and charged with the evaluation of potential environmentally superior technologies (ESTs) that have been developed and implemented at selected swine farms or facilities. The OPEN program has demonstrated the effectiveness of a new paradigm for policy-relevant environmental research related to North Carolina's animal waste management programs. This new paradigm is based on a commitment to improve scientific understanding associated with a wide array of environmental issues (i.e., issues related to the movement of N from animal waste into air, water, and soil media; the transmission of odor and odorants; disease-transmitting vectors; and airborne pathogens). The primary focus of this paper is on emissions of ammonia (NH3) from some potential ESTs that were being evaluated at full-scale swine facilities. During 2-week-long periods in two different seasons (warm and cold), NH3 fluxes from water-holding structures and NH3 emissions from animal houses or barns were measured at six potential EST sites: (1) Barham farm--in-ground ambient temperature anaerobic digester/energy recovery/greenhouse vegetable production system; (2) BOC #93 farm--upflow biofiltration system--EKOKAN; (3) Carrolls farm--aerobic blanket system--ISSUES-ABS; (4) Corbett #1 farm--solids separation/ gasification for energy and ash recovery centralized system--BEST; (5) Corbett #2 farm--solid separation/ reciprocating water technology--ReCip; and (6) Vestal farm--Recycling of Nutrient, Energy and Water System--ISSUES-RENEW. The ESTs were compared with similar measurements made at two conventional lagoon and spray technology (LST) farms (Moore farm and Stokes farm). A flow-through dynamic chamber system and two sets of open-path Fourier transform infrared (OP-FTIR) spectrometers measured NH3 fluxes continuously from water-holding structures and emissions from housing units at the EST and conventional LST sites. A statistical-observational model for lagoon NH3 flux was developed using a multiple linear regression analysis of 15-min averaged NH3 flux data against the relevant environmental parameters measured at the two conventional farms during two different seasons of the year. This was used to compare the water-holding structures at ESTs with those from lagoons at conventional sites under similar environmental conditions. Percentage reductions in NH3 emissions from different components of each potential EST, as well as the whole farm on which the EST was located were evaluated from the estimated emissions from water-holding structures, barns, etc., all normalized by the appropriate nitrogen excretion rate at the potential EST farm, as well as from the appropriate conventional farm. This study showed that ammonia emissions were reduced by all but one potential EST for both experimental periods. However, on the basis of our evaluation results and analysis and available information in the scientific literature, the evaluated alternative technologies may require additional technical modifications to be qualified as unconditional ESTs relative to NH3 emissions reductions.

Factors regulating cheese shreddability.

Two sets of cheeses were evaluated to determine factors that affect shred quality. The first set of cheeses was made up of 3 commercial cheeses, Monterey Jack, Mozzarella, and process. The second set of cheeses was made up of 3 Mozzarella cheeses with varying levels of protein and fat at a constant moisture content. A shred distribution of long shreds, short shreds, and fines was obtained by shredding blocks of cheese in a food processor. A probe tack test was used to directly measure adhesion of the cheese to a stainless-steel surface. Surface energy was determined based on the contact angles of standard liquids, and rheological characterization was done by a creep and recovery test. Creep and recovery data were used to calculate the maximum and initial compliance and retardation time. Shredding defects of fines and adhesion to the blade were observed in commercial cheeses. Mozzarella did not adhere to the blade but did produce the most fines. Both Monterey Jack and process cheeses adhered to the blade and produced fines. Furthermore, adherence to the blade was correlated positively with tack energy and negatively with retardation time. Mozzarella cheese, with the highest fat and lowest protein contents, produced the most fines but showed little adherence to the blade, even though tack energy increased with fat content. Surface energy was not correlated with shredding defects in either group of cheese. Rheological properties and tack energy appeared to be the key factors involved in shredding defects.

Dyspnoea exaggerated in the supine position and during exertion--diagnostic challenge.

The case of dyspnoea, exaggerated when in the supine position and during exertion, as a result of severe weakness of the diaphragm is reported. The aim of the study was to present a rare case of idiopathic bilateral diaphragmatic paresis (BDP) and to describe all the diagnostic procedures necessary to perform differential diagnostics. In order to establish the final diagnosis, chest radiography, haemodynamic evaluation of the circulatory system, ultrasonography, ultrasonocardiography, measurement of transdiaphragmatic pressures, scintiscanning of the lungs, spirometry, analysis of arterial blood gases, computed tomography of the thorax and external stimulation of the phrenic nerve were performed. The measurement of transdiaphragmatic pressure was crucial to establish and confirm the diagnosis of BDP, as only a small difference in gastric and oesophageal pressures during tidal breathing and inspiratory efforts was recorded. As no cause of diaphragmatic paresis was found, the case was classified as idiopathic. The final diagnosis of non-trauma related bilateral diaphragmatic weakness was generally delayed. In the case of the described patient, dyspnoea, the main symptom he was suffering from, was supposed to result from his congenital heart defect. We recommend that the suspicion of idiopathic diaphragmatic paresis should always be raised in patients suffering from respiratory failure of unknown origin. It is, however, necessary to perform extensive diagnostics to exclude the other causes of phrenic-diaphragmatic impairment. It's also necessary to consider all infections, injuries and surgical procedures within the thorax as possible causes of diaphragmatic paresis.

[Manometric examinations in esophageal peristalsis disorders]. / Manometryczne badania w zaburzeniach motoryki przelyku i wpustu.

Many centers besides radiography and endoscopy, perform manometric measurements in the diagnostics of diseases concerning esophagus and cardia. They which allow to determine esophageal body peristalsis, LES length with spatial distribution of pressures (Vector Volume). The aim of our study was the estimation of usefulness the esophageal and cardial computed manometry in disorders concerning motor activity of the upper part of gastrointestinal tract. In our hospital between March 1997 and March 1998 we examined 12 patients with cardial achalasia, 9 patients with hiatal hernia, 2 ones with features of gastroesophageal reflux without hernia and 1 patient with diffuse esophageal spasm. All patients were examined preoperatively, on the 7th postoperative day and postoperatively--after a month. Computer recording of pressures was made. In postoperative examination we revealed favourable improvement in gastroesophageal passage with marked decrease of LES pressures in patients after dilation. However in patients after Nissen's operation LES pressures exceeded upper normal range on the 7th day postoperatively, but they came back to normal range within a month after operation.

[The modified laparostomy with the use of ultrasound dissector and garamycin sponge in the treatment of complicated acute pancreatitis]. / Zmodyfikowana laparostomia z zastosowaniem dyssektora ultradzwiekowego i gabki garamycynowej w leczeniu powiklan ostrego zapalenia trzustki.

In the report a new modified technique of complicated pancreatitis treatment by laparostomy was showed. In included the use of ultrasound dissector for removing necrotic tissues and locating of garamycin sponge which should protect against secondary infection. Between January and May 1998 12 patients were treated using this method. In 8 cases (66%) we obtained rapid improvement of patients' general condition. One patient died and in 6 cases postoperative complications occurred. The use of ultrasound dissector shortens time of necrotic demarcation in pancreas and peripancreatic tissues. Garamycin sponge is effective protection from late infections concerning laparostomic wound. Modified laparostomy decreases about 50% number of secondary re-laparostomies, period of hospitalization and cost of complications treatment in acute pancreatitis in comparison with conventional method.

[Diagnostic difficulties in a case of malignant carcinoma of the small intestine. Clinical reports]. / Trudnosci diagnostyczne w przypadku nowotworu zlosliwego jelita cienkiego. Doniesienia kliniczne.

The paper presents clinical findings in four patients with malignant tumours originally arising from the jejunum, which have been diagnosed and surgically treated in the Department of Alimentary Tract Surgery during the last six years. Diagnostic problems and the patients' postoperative course have been presented. One patient had a metastatic malignancy which turned out to be the Sister Mary Joseph tumour.

[Changes in activity of antioxidant enzymes in the early period after classical and laparoscopic cholecystectomy]. / Zmiany aktywnosci enzymów antyoksydacyjnych we wczesnym okresie po cholecystektomii klasycznej i laparoskopowej.

In our study we examined the influence of surgical treatment of gallstones on erythrocyte antioxidant system. The investigated group consisted of thirty three (33) women patients 15 were operated laparoscopically and 18-by means of open cholecystectomy. Using proper criteria of classification to the study we obtained 2 similar groups of patients. We compared changes in activity of antioxidant enzymes: superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and level of lipid peroxides (MDA) in early period after operation. The study revealed that laparoscopic cholecystectomy causes minor changes in activity of antioxidant enzymes and level of MDA than open cholecystectomy. Laparoscopic method causes less "oxidative stress" in human erythrocytes which suggests its minor traumatic effect than the open method.

Measurement error, instrumental variables and corrections for attenuation with applications to meta-analyses.

MacMahon et al. present a meta-analysis of the effect of blood pressure on coronary heart disease, as well as new methods for estimation in measurement error models for the case when a replicate or second measurement is made of the fallible predictor. The correction for attenuation used by these authors is compared to others already existing in the literature, as well as to a new instrumental variable method. The assumptions justifying the various methods are examined and their efficiencies are studied via simulation. Compared to the methods we discuss, the method of MacMahon et al. may have bias in some circumstances because it does not take into account: (i) possible correlations among the predictors within a study; (ii) possible bias in the second measurement; or (iii) possibly differing marginal distributions of the predictors or measurement errors across studies. A unifying asymptotic theory using estimating equations is also presented.

Evaluation of the use of i.v. ciprofloxacin.

A drug usage evaluation was conducted at our institution, a 344-bed teaching hospital, in order to determine whether intravenous ciprofloxacin was being used appropriately based on preestablished hospital criteria.

A measurement-error model for binary and ordinal regression.

Exposure assessment poses special problems in air pollution epidemiology. This paper proposes a probit regression model for binary and ordinal outcomes that uses exposure validation information to develop estimates for the coefficient of the true exposure when only the inaccurate 'surrogate' measure of exposure is available for the individuals in the health study. This method is closely related to recently developed measurement-error methods, and is based on the assumption that the outcome and the surrogate exposure are conditionally independent given the true exposure. A test statistic is proposed for checking this conditional independence assumption when more than one surrogate is available, and an interpretation of the coefficient estimate is provided in the event that the assumption is violated. The methods are applied to an example involving nitrogen dioxide exposure and wheeze in children.