“Thermal transport through < 100 > and < 110 > rough Si nanowires selleck chemical is investigated using an atomistic quantum transport approach based on a modified Keating model and the wave function formalism. The thermal conductance, resistance, and conductivity are calculated for different nanowire lengths and the root mean square of the rough surfaces. The simulation results show that thermal transport is diffusive in rough nanowires without surrounding oxide layers. Its degradation,
as compared to ideal structures, cannot be attributed to phonon localization effects, but to the properties of the phonon band structure. Phonon bands with an almost flat dispersion cannot propagate through disordered structures due to the mode mismatch between adjacent unit cells. (c) 2011 American Institute of Physics. [doi: 10.1063/1.3644993]“
“Background: Sleep problems associated with chronic obstructive pulmonary disease may have an important impact
on quality of life and health outcome measures in patients. The aim of this study was to prospectively assess differences in symptom profile and polysomnographic parameters in patients with stable mild to moderate COPD and age, gender, and body-mass-index matched controls without airflow obstruction.\n\nMethods: The Sleep Disorders Questionnaire was administered to both patients and controls prior to clinical and polysomnographic evaluation. Responses obtained from the questionnaire were used
to construct four independent symptom scales: sleep apnea, periodic limb www.selleckchem.com/products/nu7441.html movement syndrome, psychiatric MEK inhibitor sleep disorder, and narcolepsy. Associations between each diagnostic scale and sleep parameters were considered by means of multiple analyses of covariance.\n\nResults: Fifty-two patients with mild-to-moderate COPD (age 62 +/- 8 years, BMI 29 +/- 7 kg/sqm) and 52 age, gender, and body-weight matched controls without COPD were studied. Patients with COPD had overall lower sleep efficiency, a lower total sleep time, and lower mean overnight oxygen saturation compared to controls. Patients with COPD were significantly more likely to report symptoms such as insomnia and difficulty in initiating and maintaining sleep, resulting in overall higher psychiatric sleep disorder scale scores in patients compared with controls. Minimum oxygen saturation was an independent predictor for all symptom scales. After correcting for potentially confounding factors, including pack/years of smoking, total sleep time, sleep efficiency, arousal index, mean and minimum oxygen saturation, and apnea-hypopnea-index, the between group-differences for both the periodic limb movement and psychiatric sleep disorder scale scores remained statistically significant.\n\nConclusions: We observed significant differences in both quantity and quality of sleep between patients with stable mild to moderate chronic obstructive pulmonary disease and respective controls.