AN OBJECTIVE AND PARSIMONIOUS APPROACH FOR CLASSIFYING NATURAL FLOW REGIMES AT A CONTINENTAL SCALE

Hydro‐ecological stream classification—the process of grouping streams by similar hydrologic responses and, by extension, similar aquatic habitat—has been widely accepted and is considered by some to be one of the first steps towards developing ecological flow targets. A new classification of 1543 streamgauges in the contiguous USA is presented by use of a novel and parsimonious approach to understand similarity in ecological streamflow response. This novel classification approach uses seven fundamental daily streamflow statistics (FDSS) rather than winnowing down an uncorrelated subset from 200 or more ecologically relevant streamflow statistics (ERSS) commonly used in hydro‐ecological classification studies. The results of this investigation demonstrate that the distributions of 33 tested ERSS are consistently different among the classification groups derived from the seven FDSS. It is further shown that classification based solely on the 33 ERSS generally does a poorer job in grouping similar streamgauges than the classification based on the seven FDSS. This new classification approach has the additional advantages of overcoming some of the subjectivity associated with the selection of the classification variables and provides a set of robust continental‐scale classes of US streamgauges. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.     

Absence of correlation between Sry polymorphisms and XY sex reversal caused by the M. m. domesticus Y chromosome

The difference between the responses of phenylephrine (1 microM)-precontracted vascular (endothelium-denuded rat or rabbit aortic strips) and nonvascular (rat anococcygeus muscle) smooth muscles to acetylcholine (0.1-100 microM) was investigated when they were mounted co-axially inside the tracheas isolated from normal or ovalbumin-sensitized guinea-pigs. Acetylcholine produced concentration-dependent relaxations in both types of bioassay tissues. These relaxations, previously shown to be due to the release of airway epithelium-derived relaxing factor(s), were significantly attenuated when the epithelial layer of the tracheas was removed mechanically (as confirmed by histological examination). There were no significant differences in responsiveness to acetylcholine between vascular strips mounted inside the epithelium-intact normal or sensitized tracheas. The phenylephrine-induced precontraction was significantly more pronounced in rat anococcygeus muscles mounted inside sensitized tracheas as compared to tissues mounted inside control tracheas. The acetylcholine-induced relaxations were significantly decreased but this effect disappeared when the concentration of phenylephrine was reduced to obtain a similar precontraction level as in tissues mounted inside control tracheas. The responsiveness of both vascular strips and anococcygeus muscles to acetylcholine was attenuated when they were mounted inside sensitized tracheas and incubated with ovalbumin for 20 min, which may be explained by the epithelial damage induced by ovalbumin challenge. This attenuation was absent when co-axial pairs, utilizing normal tracheas, were used. These results indicate a difference in response patterns of the rat anococcygeus muscle and vascular strips in ovalbumin-sensitized tracheas, which should be taken into consideration in co-axial bioassay studies.     

Carbon nanotube enhanced diffraction efficiency in dye-doped liquid crystal

We report on the optical properties of nematic liquid crystal cells containing the liquid crystal E7 doped with the azo dye Methyl Red at percentages ranging from 0.4% to 0.8% and 0.002% single-wall carbon nanotubes. From polarized absorption measurements an order parameter of S = 0.605 was obtained, showing that the dye molecules align themselves very well with the liquid crystal's director axis. Diffraction efficiencies of 532-nm pump and 670-nm probe beams were measured. Efficiencies and rise times were found to increase with dye concentration. A maximum efficiency of 5.8% was found for cells doped with carbon nanotubes, while cells without carbon nanotubes had a maximum efficiency of 3.2%. Therefore the presence of carbon nanotubes enhanced the diffraction efficiency by a factor of 1.8. The nonlinear index coefficient, n₂, was calculated to be 18 × 10^?3 cm²/W. The data are consistent with a grating formation based on trans-cis photoisomerism of the dye molecules that leads to a reorientation of the liquid crystal phase. These photonic devices are functional without the application of any external field, are easily prepared, and have lifetimes in excess of two years without any indication of degradation when stored at ambient temperatures.     

Chromium-induced genotoxicity and apoptosis: relationship to chromium carcinogenesis (review)

The adverse health effects linked with chromium (Cr) exposure, the role of solubility and chemical speciation of Cr compounds, and the diverse cellular and molecular effects of Cr make the study of Cr carcinogenesis and toxicology very interesting and complex. Certain Cr compounds are prominent metal carcinogens in both occupational and environmental settings. Inhaled particulate forms of hexavalent Cr [Cr(VI)] cause lung cancer as well as lung toxicity. Some of the important factors in determining the biological outcome of Cr exposure include the bioavailability, chemical speciation and solubility of Cr compounds, intracellular reduction, and interaction of Cr with DNA. The stable oxidation states of Cr found in nature are Cr(III) and Cr(VI). Cr(III) is unable to enter cells but Cr(VI) enters into cells through membrane anionic transporters. Intracellular Cr(VI) is metabolically reduced to the ultimate Cr(III). Cr(VI) does not react with macromolecules such as DNA, RNA, proteins and lipids. However, both Cr(III) and the reductional intermediate Cr(V) are capable of co-ordinate covalent interactions with macromolecules. At the genomic level, Cr genotoxicity manifests as gene mutations, several types of DNA lesions and inhibition of macromolecular synthesis. At the cellular level, Cr exposure may lead to cell cycle arrest, apoptosis, premature terminal growth arrest, or neoplastic transformation. Cr-induced DNA-DNA interstrand crosslinks (DDC), the tumor suppressor gene p53 and oxidative processes are some of the major factors that may play a significant role in determining the cellular outcome in response to Cr exposure. We have utilized cellular, molecular, pharmacological, and genetic approaches to understand the interrelationship between Cr-induced genotoxicity, apoptosis and carcinogenesis. This review is based on the results and inferences of this research. We hope this review will clarify existing concepts and also introduce novel perspectives in chromium carcinogenesis research.     

Defining the physician's duty to warn: consensus statement of Ontario's Medical Expert Panel on Duty to Inform

Ontario's Medical Expert Panel on Duty to Inform was formed to consider the duty of Ontario physicians in circumstances where a patient threatens to kill or cause serious bodily harm to a third party. The panel was concerned about the implications of any duty to inform on the integrity of the physician-patient relationship, particularly with respect to confidentiality. The panel agreed that regulations safeguarding the confidentiality of patient information ought to be changed only if there is a critical reason for doing so, but, after deliberation, the panel members concluded that the need to protect the public from serious risk of harm is a paramount concern that should supersede the duty of confidentiality. The recommendations reported here were endorsed in principle by the panelists and the groups they represented (the Royal College of Physicians and Surgeons of Canada, the Canadian Medical Protective Association, the College of Physicians and Surgeons of Ontario, the Ontario College of Family Physicians and the Ontario Medical Association) and are being implemented by the College of Physicians and Surgeons of Ontario.     

Adiposity and cardiovascular risk factors in men with obstructive sleep apnea

STUDY OBJECTIVE: To assess anthropometric characteristics of patients with obstructive sleep apnea (OSA) and their relationship to cardiovascular risk factors (dyslipidemia, hypertension, glucose intolerance) and severity of breathing abnormalities during sleep. DESIGN: Case series. SETTING: Referral-based sleep disorder center serving Rhode Island and Southeastern Massachusetts. PATIENTS: Forty-five men, 26 to 65 years old, with OSA diagnosed by clinical and polysomnographic criteria. RESULTS: By national health survey criteria, 51 percent of patients were in the upper fifth percentile for weight, whereas 91 to 98 percent were in the upper fifth percentile for skinfold thicknesses (triceps, subscapular, triceps plus subscapular). Severe upper body obesity, as defined by a waist-hip ratio (WHR) greater than or equal to 1.00, was present in 51 percent of the patients. The WHR, however, did not correlate significantly with the severity of respiratory disturbances during sleep. The patients had higher prevalences of hypertension and impaired glucose tolerance than expected, but normal prevalences of hypercholesterolemia, low high-density lipoprotein cholesterol, and overt diabetes mellitus. Skinfold thicknesses correlated more closely with the severity of OSA than did body mass index (BMI) or neck circumference. CONCLUSION: Men with OSA have a marked excess of body fat that is not always reflected in measurements of body weight or BMI. Also, upper body obesity, hypertension, and impaired glucose tolerance occur more frequently than expected in this population. Severe adiposity may not only promote development of the respiratory abnormalities of OSA, but also may contribute directly to the increased cardiovascular risk associated with OSA.     

Performance bounds for trellis-coded modulation on time-dispersivechannels

The performance of trellis-coded modulation (TCM) on additive white Gaussian noise channels is well understood, and tight analytical bounds exist on the probability of the Viterbi decoder making a decision error. When a channel is also time-dispersive, the performance of TCM systems has been studied mainly by simulation. However, simulation is limited to symbol error probabilities greater than 10^-6 and is not a particularly useful tool for designing codes. Tight analytical bounds on the error probability of TCM on time-dispersive channels are required for a more thorough study of performance. Moreover, the design of good codes and optimum metrics for time-dispersive channels requires tight analytical bounds. In this paper we derive analytical upper bounds, which, although requiring numerical techniques for tractable evaluation, are tight for a wide range of time-dispersive channel conditions. The bounds are based on a union bound of error events that leads to a summation of pairwise error probabilities, which are themselves upper bounded