2,116 research outputs found
Phonon density of states and compression behavior in iron sulfide under pressure
We report the partial phonon densities of states (DOS) of iron sulfide, a possible component of the rocky planet's core, measured by the Fe-57 nuclear resonant inelastic x-ray scattering and calculate the total phonon DOS under pressure. From the phonon DOS, we drive thermodynamic parameters. A comparison of the observed and estimated compressibilities makes it clear that there is a large pure electronic contribution in the observed compressibility in the metallic state. Our results present the observation of thermodynamic parameters of iron sulfide with the low-spin state of an Fe2+ ion at the high density, which is similar to the condition of the Martian core
Results of a novel screening tool measuring dietary sodium knowledge in patients with chronic kidney disease.
BackgroundReducing dietary sodium has potential to benefit patients with chronic kidney disease (CKD). Little research is available defining dietary sodium knowledge gaps in patients with pre-dialysis CKD. We designed a brief screening tool to rapidly identify patient knowledge gaps related to dietary sodium for patients with CKD not yet on dialysis.MethodsA Short Sodium Knowledge Survey (SSKS) was developed and administered to patients with pre-dialysis CKD. We also asked patients if they received counseling on dietary sodium reduction and about recommended intake limits. We performed logistic regression to examine the association between sodium knowledge and patient characteristics. Characteristics of patients who answered all SSKS questions correctly were compared to those who did not.ResultsOne-hundred fifty-five patients were surveyed. The mean (SD) age was 56.6 (15.1) years, 84 (54%) were men, and 119 (77%) were white. Sixty-seven patients (43.2%) correctly identified their daily intake sodium limit. Fifty-eight (37.4%) were unable to answer all survey questions correctly. In analysis adjusted for age, sex, race, education, health literacy, CKD stage, self-reported hypertension and attendance in a kidney education class, women and patients of non-white race had lower odds of correctly answering survey questions (0.36 [0.16,0.81]; p = 0.01 women versus men and 0.33 [0.14,0.76]; p = 0.01 non-white versus white, respectively).ConclusionsOur survey provides a mechanism to quickly identify dietary sodium knowledge gaps in patients with CKD. Women and patients of non-white race may have knowledge barriers impeding adherence to sodium reduction advice
Magneto-x-ray effects in transition-metal alloys
We present a theory that combines the relativistic spin-polarized version of the Koringa-Kohn-Rostoker coherent-potential approximation theory and the macroscopic theory of magneto-optical effects enabling us to calculate magneto-x-ray effects from first principles. The theory is illustrated by calculation of Faraday and Kerr rotations and ellipticities for transition-metal alloys
Prevaccination screening of health care workers for immunity to measles, rubella, mumps and varicella in a developing country. What do we save?
SummaryA structured questionnaire was administered to health-care workers (HCWs). The HCWs were also screened for measles, rubella, mumps, and varicella (MMRV) using serological methods. One thousand two hundred and fifty-five HCWs were tested. Of the HCWs examined, 94% were immune to measles, 97% to rubella, 90% to mumps and 98% to varicella. The positive predictive values of histories of measles, mumps, rubella and varicella were 96%, 93%, 100% and 98%, respectively. The negative predictive values of histories of measles, mumps, rubella and varicella were 13%, 17%, 5% and 2%, respectively. The cost of vaccination without screening was significantly more expensive (cost difference: €24,385) for varicella, although vaccination without screening was cheap (cost difference: €5693) for MMR. Although the use of cheaper vaccines supports the implementation of vaccination programs without screening, the cost of vaccination should not be calculated based only on the direct costs. The indirect costs associated with lost work time due to vaccination and its side effects and the direct costs of potential side effects should be considered. However, if prescreening is not conducted, some HCWs (2–7%) would be unprotected against these contagious illnesses because of the unreliability of their MMRV history. In conclusion, the screening of HCWs before vaccination continues to be advisable
Systematic X-ray absorption study of hole doping in BSCCO - phases
X-ray absorption spectroscopy (XAS) on the O 1s threshold was applied to
Bi-based, single crystalline high temperature superconductors (HTc's), whose
hole densities in the CuO2 planes was varied by different methods. XAS gives
the intensity of the so-called pre-peak of the O 1s line due to the unoccupied
part of the Zhang-Rice (ZR) singlet state. The effects of variation of the
number n of CuO2 - planes per unit cell (n = 1,2,3) and the effect of
La-substitution for Sr for the n = 1 and n = 2 phase were studied
systematically. Furthermore the symmetry of the states could be probed by the
polarization of the impinging radiation.Comment: 4 pages, 2 figures, to appear in the proceedings of SCES2001, Ann
Arbor, August 6-10, 200
A general moment NRIXS approach to the determination of equilibrium Fe isotopic fractionation factors: application to goethite and jarosite
We measured the reduced partition function ratios for iron isotopes in
goethite FeO(OH), potassium-jarosite KFe3(SO4)2(OH)6, and hydronium-jarosite
(H3O)Fe3(SO4)2(OH)6, by Nuclear Resonant Inelastic X-Ray Scattering (NRIXS,
also known as Nuclear Resonance Vibrational Spectroscopy -NRVS- or Nuclear
Inelastic Scattering -NIS) at the Advanced Photon Source. These measurements
were made on synthetic minerals enriched in 57Fe. A new method (i.e., the
general moment approach) is presented to calculate {\beta}-factors from the
moments of the NRIXS spectrum S(E). The first term in the moment expansion
controls iron isotopic fractionation at high temperature and corresponds to the
mean force constant of the iron bonds, a quantity that is readily measured and
often reported in NRIXS studies.Comment: 38 pages, 2 tables, 8 figures. In press at Geochimica et Cosmochimica
Acta. Appendix C contains new derivations relating the moments of the iron
PDOS to the moments of the excitation probability function measured in
Nuclear Resonant Inelastic X-ray Scatterin
Interleukin-1 regulates multiple atherogenic mechanisms in response to fat feeding
Background: Atherosclerosis is an inflammatory process that develops in individuals with known risk factors that include hypertension and hyperlipidaemia, influenced by diet. However, the interplay between diet, inflammatory mechanisms and vascular risk factors requires further research. We hypothesised that interleukin-1 (IL-1) signaling in the vessel wall would raise arterial blood pressure and promote atheroma.
Methodology/Principal Findings: Apoe(-/-) and Apoe(-/-)/IL-1R1(-/-) mice were fed high fat diets for 8 weeks, and their blood pressure and atherosclerosis development measured. Apoe(-/-)/IL-R1(-/-) mice had a reduced blood pressure and significantly less atheroma than Apoe(-/-) mice. Selective loss of IL-1 signaling in the vessel wall by bone marrow transplantation also reduced plaque burden (p<0.05). This was associated with an IL-1 mediated loss of endothelium-dependent relaxation and an increase in vessel wall Nox 4. Inhibition of IL-1 restored endothelium-dependent vasodilatation and reduced levels of arterial oxidative stress.
Conclusions/Significance: The IL-1 cytokine system links atherogenic environmental stimuli with arterial inflammation, oxidative stress, increased blood pressure and atherosclerosis. This is the first demonstration that inhibition of a single cytokine can block the rise in blood pressure in response to an environmental stimulus. IL-1 inhibition may have profound beneficial effects on atherogenesis in man
Processing Tincal Ores using Ultrasonic Waves
ABSTRACT: In this study, effects of ultrasonic sound waves have been studied on the processing of tincal ores using ultrasonic baths producing 35 kHz frequency and 1.24 W/cm 2 intensity. Tincal ores (24.37 90B2O3) were processed in saturated solutions for 15 minutes and a concentrate containing 35.29 % B2O1 was obtained with 95.69 % recovery. During ultrasonic treatment boron minerals were found to corrode to a small extent. These findings showed that efficiency of dispersion process was proportional to directly treatment time and indirectly to the sample quantity, solids density and particle size
Quantum Algorithms for Learning and Testing Juntas
In this article we develop quantum algorithms for learning and testing
juntas, i.e. Boolean functions which depend only on an unknown set of k out of
n input variables. Our aim is to develop efficient algorithms:
- whose sample complexity has no dependence on n, the dimension of the domain
the Boolean functions are defined over;
- with no access to any classical or quantum membership ("black-box")
queries. Instead, our algorithms use only classical examples generated
uniformly at random and fixed quantum superpositions of such classical
examples;
- which require only a few quantum examples but possibly many classical
random examples (which are considered quite "cheap" relative to quantum
examples).
Our quantum algorithms are based on a subroutine FS which enables sampling
according to the Fourier spectrum of f; the FS subroutine was used in earlier
work of Bshouty and Jackson on quantum learning. Our results are as follows:
- We give an algorithm for testing k-juntas to accuracy that uses
quantum examples. This improves on the number of examples used
by the best known classical algorithm.
- We establish the following lower bound: any FS-based k-junta testing
algorithm requires queries.
- We give an algorithm for learning -juntas to accuracy that
uses quantum examples and
random examples. We show that this learning algorithms is close to optimal by
giving a related lower bound.Comment: 15 pages, 1 figure. Uses synttree package. To appear in Quantum
Information Processin
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