Mesoscopic Transport: The Electron-Gas Sum Rules in a Driven Quantum Point Contact

The nature of the electron gas is characterized, above all, by its multi-particle correlations. The conserving sum rules for the electron gas have been thoroughly studied for many years, and their centrality to the physics of metallic conduction is widely understood (at least in the many-body community). We review the role of the conserving sum rules in mesoscopic transport, as normative criteria for assessing the conserving status of mesoscopic models. In themselves, the sum rules are specific enough to rule out any such theory if it fails to respect the conservation laws. Of greater interest is the capacity of the compressibility sum rule, in particular, to reveal unexpected fluctuation effects in nonuniform mesoscopic structures.Comment: TeX, 11pp, no fi

Where is the shot noise of a quantum point contact?

Reznikov et al. [Phys. Rev. Lett. 75, 3340 (1995)] have presented definitive observations of nonequilibrium noise in a quantum point contact. Especially puzzling is the “anomalous” peak structure of the excess noise measured at constant current; to date it remains unexplained. We show that their experiment directly reveals the deep link between conservation principles in the electron gas and its low-dimensional, mesoscopic behavior. The keys to that connection are gauge invariance and the compressibility sum rule. These are central not only to the experiment of Reznikov et al., but to the very nature of all mesoscopic transport

Aerosol optical depths at Mohal-Kullu in the northwestern Indian Himalayan high altitude station during ICARB

First time observations of spectral aerosol optical depths (AODs) at Mohal (31.9°N, 77.11°E; altitude 1154 m amsl) in the Kullu valley, located in the northwestern Indian Himalayan region, have been carried out during Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB), as a part of the Indian Space Research Organisation-Geosphere Biosphere Program (ISRO-GBP). AODs at six wavelengths are obtained using Microtops-II Sunphotometer and Ozonometer. The monthly mean values of AOD at 500 nm are found to be 0.27 ± 0.04 and 0.24 ± 0.02 during March and April, 2006 respectively. However, their monthly mean values are 0.33 ± 0.04 at 380 nm and 0.20 ± 0.03 nm at 870 nm during March 2006 and 0.31 ± 0.3 at 380 nm and 0.17 ± 0.2 at 870 nm during April 2006, showing a gradual decrease in AOD with wavelength. The Angstrom wavelength exponent 'α' had a mean value of 0.72 ± 0.05, implying reduced dominance of fine particles. Further, the afternoon AOD values are higher as compared to forenoon values by ~33.0% during March and by ~9.0% during April 2006 and are attributed to the pollutant lifted up from the valley by the evolving boundary layer. Besides the long-range transportation of aerosol particles by airmass from the Great Sahara and the Thar Desert regions to the observing site, the high values of AODs have also been influenced by biomass burning and frequent incidents of forest fire at local levels

A method for measuring the Neel relaxation time in a frozen ferrofluid

We report a novel method of determining the average Neel relaxation time and its temperature dependence by calculating derivatives of the measured time dependence of temperature for a frozen ferrofluid exposed to an alternating magnetic field. The ferrofluid, composed of dextran-coated Fe3O4 nanoparticles (diameter 13.7 nm +/- 4.7 nm), was synthesized via wet chemical precipitation and characterized by x-ray diffraction and transmission electron microscopy. An alternating magnetic field of constant amplitude (H0 = 20 kA/m) driven at frequencies of 171 kHz, 232 kHz and 343 kHz was used to determine the temperature dependent magnetic energy absorption rate in the temperature range from 160 K to 210 K. We found that the specific absorption rate of the ferrofluid decreased monotonically with temperature over this range at the given frequencies. From these measured data, we determined the temperature dependence of the Neel relaxation time and estimate a room-temperature magnetocrystalline anisotropy constant of 40 kJ/m3, in agreement with previously published results

Raman spectral signatures of mouse mammary tissue and associated lymph nodes: normal, tumor and mastitis

Raman spectroscopy involves the interaction of light with the molecular vibrations and therefore can provide information about molecular structure, tissue composition and changes in its environment. We explored whether Raman spectroscopy can reliably distinguish mammary tumors from normal mammary tissues and other pathological states in mice. We analyzed a large number of Raman spectra from the tumor and normal mammary glands of mice injected with 4T1 tumor cells, which were collected using a high-resolution (less than 4 cm −1 ) Raman spectrometer at a fixed (785 nm) laser excitation wavelength and with 60 mW of laser power. The spectra of normal and tumor mammary glands showed consistent differences in the intensity of certain Raman bands and loss of some bands in the tumor spectra. Multivariate statistical methods—principal component analysis (PCA) and discriminant functional analysis (DFA)—were used to separate the data into different groups of mammary tumors, mastitis, lymph nodes contralateral and tumor-cell-injected sides, and normal contralateral and tumor-cell-injected sides. We demonstrate that this spectroscopic technique has the feasibility of discriminating tumor and mastitis from normal tissues and other pathological states in a short period of time and may detect tumor transformation earlier than the standard histological examination stage. Copyright © 2006 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/55947/1/1565_ftp.pd

Transport injuries and deaths in the Eastern Mediterranean Region : findings from the Global Burden of Disease 2015 Study

Transport injuries (TI) are ranked as one of the leading causes of death, disability, and property loss worldwide. This paper provides an overview of the burden of TI in the Eastern Mediterranean Region (EMR) by age and sex from 1990 to 2015. Transport injuries mortality in the EMR was estimated using the Global Burden of Disease mortality database, with corrections for ill-defined causes of death, using the cause of death ensemble modeling tool. Morbidity estimation was based on inpatient and outpatient datasets, 26 cause-of-injury and 47 nature-of-injury categories. In 2015, 152,855 (95% uncertainty interval: 137,900-168,100) people died from TI in the EMR countries. Between 1990 and 2015, the years of life lost (YLL) rate per 100,000 due to TI decreased by 15.5%, while the years lived with disability (YLD) rate decreased by 10%, and the age-standardized disability-adjusted life years (DALYs) rate decreased by 16%. Although the burden of TI mortality and morbidity decreased over the last two decades, there is still a considerable burden that needs to be addressed by increasing awareness, enforcing laws, and improving road conditions.Peer reviewe

Prevalence and attributable health burden of chronic respiratory diseases, 1990–2017: A systematic analysis for the global burden of disease study 2017

© 2020 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license Background: Previous attempts to characterise the burden of chronic respiratory diseases have focused only on specific disease conditions, such as chronic obstructive pulmonary disease (COPD) or asthma. In this study, we aimed to characterise the burden of chronic respiratory diseases globally, providing a comprehensive and up-to-date analysis on geographical and time trends from 1990 to 2017. Methods: Using data from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2017, we estimated the prevalence, morbidity, and mortality attributable to chronic respiratory diseases through an analysis of deaths, disability-adjusted life-years (DALYs), and years of life lost (YLL) by GBD super-region, from 1990 to 2017, stratified by age and sex. Specific diseases analysed included asthma, COPD, interstitial lung disease and pulmonary sarcoidosis, pneumoconiosis, and other chronic respiratory diseases. We also assessed the contribution of risk factors (smoking, second-hand smoke, ambient particulate matter and ozone pollution, household air pollution from solid fuels, and occupational risks) to chronic respiratory disease-attributable DALYs. Findings: In 2017, 544·9 million people (95% uncertainty interval [UI] 506·9–584·8) worldwide had a chronic respiratory disease, representing an increase of 39·8% compared with 1990. Chronic respiratory disease prevalence showed wide variability across GBD super-regions, with the highest prevalence among both males and females in high-income regions, and the lowest prevalence in sub-Saharan Africa and south Asia. The age-sex-specific prevalence of each chronic respiratory disease in 2017 was also highly variable geographically. Chronic respiratory diseases were the third leading cause of death in 2017 (7·0% [95% UI 6·8–7·2] of all deaths), behind cardiovascular diseases and neoplasms. Deaths due to chronic respiratory diseases numbered 3 914 196 (95% UI 3 790 578–4 044 819) in 2017, an increase of 18·0% since 1990, while total DALYs increased by 13·3%. However, when accounting for ageing and population growth, declines were observed in age-standardised prevalence (14·3% decrease), age-standardised death rates (42·6%), and age-standardised DALY rates (38·2%). In males and females, most chronic respiratory disease-attributable deaths and DALYs were due to COPD. In regional analyses, mortality rates from chronic respiratory diseases were greatest in south Asia and lowest in sub-Saharan Africa, also across both sexes. Notably, although absolute prevalence was lower in south Asia than in most other super-regions, YLLs due to chronic respiratory diseases across the subcontinent were the highest in the world. Death rates due to interstitial lung disease and pulmonary sarcoidosis were greater than those due to pneumoconiosis in all super-regions. Smoking was the leading risk factor for chronic respiratory disease-related disability across all regions for men. Among women, household air pollution from solid fuels was the predominant risk factor for chronic respiratory diseases in south Asia and sub-Saharan Africa, while ambient particulate matter represented the leading risk factor in southeast Asia, east Asia, and Oceania, and in the Middle East and north Africa super-region. Interpretation: Our study shows that chronic respiratory diseases remain a leading cause of death and disability worldwide, with growth in absolute numbers but sharp declines in several age-standardised estimators since 1990. Premature mortality from chronic respiratory diseases seems to be highest in regions with less-resourced health systems on a per-capita basis. Funding: Bill & Melinda Gates Foundation