132 research outputs found
Supercell studies of the Fermi surface changes in the electron-doped superconductor LaFeAsO1‑xFx
We study the changes in the Fermi surface with electron doping in the LaFeAsO1‑xFx superconductors with density-functional supercell calculations using the linearized augmented plane-wave method. The supercell calculations with explicit F substitution are compared with those obtained from the virtual-crystal approximation (VCA) and from a simple rigid-band shift. We find significant differences between the supercell results and those obtained from the rigid-band shift with electron doping, although quite remarkably the supercell results are in good agreement with the VCA where the nuclear charges of the O atoms are slightly increased to mimic the addition of the extra electrons. With electron doping, the two cylindrical hole pockets along Γ-Z shrink in size, and the third hole pocket around Z disappears for an electron-doping concentration in excess of about 7%-8%, while the two elliptical electron cylinders along M-A expand in size. The spin-orbit coupling does not affect the Fermi surface much except a somewhat reduction in the size of the third hole pocket in the undoped case. We find that with the addition of the electrons the antiferromagnetic state becomes energetically less stable as compared to the nonmagnetic state, indicating that the electron doping may provide an extra degree of stability to the formation of the superconducting ground state.This work was supported by the U.S. Department of Energy under Grant No. DE-FG02-00ER45818
Implementation of a Modem for Narrow Bandwidth Channel Using 6713 DSK
As communication plays an important role in day to day life, the effective and efficient voice transmission is to be maintained. This paper mainly deals with voice transmission over a channel and implemented using 6713 DSK. For this purpose, some modulation schemes and voice coders are implemented. So two points of view are developed. First, a static point of view, using a prototype on MATLAB, estimates the different combinations\u27 performances, using a stored speech sample. Then, a more dynamic point of view tests the system in real time, using C code adapted from MATLAB and embedded on DSPs, with the actual transmission channel being emulated by another DSP. In MATLAB the voice signal using different techniques are simulated and the outputs for modulation and demodulation signal are obtained which are shown in this paper for random bits operation of signals. An optimal transmission/reception scheme intended for voice transmission on DSP Processor TMS320C6713 is done using hardware and the results are compared in MATLAB by maintaining proper accuracy
Bronchoprotective effect of Zingiber officinale roscoe (Ginger) in guinea pigs
Background: To evaluate the bronchoprotective effect of aqueous extract of Zingiber officinale (AZO) in guinea pigs and compare the same with that of standard drugs.Methods: Guinea pigs of either sex weighing between 350 to 450 Grams were randomly divided into 13 groups, each group containing 6 animals. Bronchospasm was induced by placing guinea pigs in histamine exposition chamber and exposing them to either 0.25% of histamine acid phosphate or 10% acetyl choline through a nebuliser under 40mm Hg pressure. The time for development of asphyxia was noted. After two and half hours, the animals were administered orally with vehicle / drugs as per the following: Gr I- Normal saline 1ml/100 Grams, Gr II- Salbutamol 1.6mg/kg, Gr III- Chlorpheniramine maleate 0.8mg/kg, Gr IV to Gr VI- AZO 200, 400, and 800mg/kg, Gr VII- AZO 200mg/kg and Salbutamol 0.8mg/kg. For acetylcholine-induced Bronchospasm Gr III animals received atropine 2mg/kg and Gr VII was not taken, rest others remaining the same. After 1 hour of treatment, the animals were again exposed to histamine or acetyl choline aerosol. The exposition time for each animal was again noted and mean increase or decrease in exposition time were noted. The data were subjected to stastical analysis by using paired ‘t’ test. Percentage of protection was also calculated.Results: AZO at all the doses studied (except 200mg/kg), showed highly significant increase in exposition time against histamine-induced bronchospasm. Combination of AZO (200mg/kg) with salbutamol (0.8mg/kg) also produced augmented effect. But against Acetylcholine induced bronchospasm, AZO did not produce any significant protective effect at any of the doses.Conclusions: AZO produced significant dose dependant bronchoprotection against histamine induced bronchospasm which might be due to antihistaminic action
Electronic Shell Structure and Relative Abundances of Cesium-Coated C60
URL:http://link.aps.org/doi/10.1103/PhysRevLett.77.1127
DOI:10.1103/PhysRevLett.77.1127The relative abundances of C60Cs(N), N≤500, determined from mass spectra measurements, are presented and explained in terms of the successive filling of the electronic shells by the cesium valence electrons. The motion of the Cs valence electrons, confined to a metal layer surrounding the C60 molecule, is described within the jellium model, with Cs spread into a uniform positive background. The electronic shell structure is calculated with the local approximation to density-functional theory and is shown to correspond to measured abundances. Strong Friedel oscillations in the electronic density are found and closed forms for them are given for jellium spheres both with and without the void.M. S. and S. S. would like to thank the Research
Board of the University of Missouri for partial financial assistance
Atypical mycotic lesion in the guttural pouch of a Thoroughbred race horse
A six-year-old Thoroughbred race horse was presented with left unilateral mucopurulent nasal discharge. Endoscopic examination revealed atypical mycotic lesion within the guttural pouch in which the fungal mass was not located on any neurovascular structures. This case was successfully treated by the combination of manual debulking of fungal diphtheritic plaques and medical treatment that included daily local irrigation and systemic medication. There were no complications and the horse returned to race three weeks later
The measurement of liner - piston skirt oil film thickness by an ultrasonic means
The paper presents a novel method for the
measurement of lubricant film thickness in the
piston-liner contact. Direct measurement of the film
in this conjunction has always posed a problem,
particularly under fired conditions. The principle is
based on capturing and analysing the reflection of
an ultrasonic pulse at the oil film. The proportion of
the wave amplitude reflected can be related to the
thickness of the oil film. A single cylinder 4-stroke
engine on a dyno test platform was used for
evaluation of the method. A piezo-electric
transducer was bonded to the outside of the
cylinder liner and used to emit high frequency short
duration ultrasonic pulses. These pulses were used
to determine the oil film thickness as the piston
skirt passed over the sensor location. Oil films in the
range 2 to 21 μm were recorded varying with
engine speeds. The results have been shown to be
in agreement with detailed numerical predictions
SmartEx: a case study on user profiling and adaptation in exhibition booths
An investigation into user profiling and adaptation with exhibition booth as a case study is reported. First a review of the field of exhibitions and trade fairs and a summary introduction to adaptation and profiling are given. We then introduce three criteria for the evaluation of exhibition booth: effectiveness, efficiency and affect. Effectiveness is related the amount of information collected, efficiency is a measurement of the time taken to collect the information, and affect is the perception of the experience and the mood booth visitors have during and after their visit. We have selected these criteria to assess adaptive and profiled exhibition booths, we call smart exhibition (SmartEx). The assessment is performed with an experiment with three test conditions (non-profiled/non adaptive, profiled/non-adaptive and profiled adaptive presentations). Results of the experiment are presented along discussion. While there is significant improvements of effectiveness and efficiency between the two-first test conditions, the improvement is not significant for the last test condition, for reasons explained. As for the affect, the results show that it has an under-estimated importance in people minds and that it should be addressed more carefully
The Measurement of Liner - Piston Skirt Oil Film Thickness by an Ultrasonic Means
The paper presents a novel method for the
measurement of lubricant film thickness in the
piston-liner contact. Direct measurement of the film
in this conjunction has always posed a problem,
particularly under fired conditions. The principle is
based on capturing and analysing the reflection of
an ultrasonic pulse at the oil film. The proportion of
the wave amplitude reflected can be related to the
thickness of the oil film. A single cylinder 4-stroke
engine on a dyno test platform was used for
evaluation of the method. A piezo-electric
transducer was bonded to the outside of the
cylinder liner and used to emit high frequency short
duration ultrasonic pulses. These pulses were used
to determine the oil film thickness as the piston
skirt passed over the sensor location. Oil films in the
range 2 to 21 μm were recorded varying with
engine speeds. The results have been shown to be
in agreement with detailed numerical predictions
Deep Rooting In-Situ Expansion of mtDNA Haplogroup R8 in South Asia
The phylogeny of the indigenous Indian-specific mitochondrial DNA (mtDNA) haplogroups have been determined and refined in previous reports. Similar to mtDNA superhaplogroups M and N, a profusion of reports are also available for superhaplogroup R. However, there is a dearth of information on South Asian subhaplogroups in particular, including R8. Therefore, we ought to access the genealogy and pre-historic expansion of haplogroup R8 which is considered one of the autochthonous lineages of South Asia.Upon screening the mtDNA of 5,836 individuals belonging to 104 distinct ethnic populations of the Indian subcontinent, we found 54 individuals with the HVS-I motif that defines the R8 haplogroup. Complete mtDNA sequencing of these 54 individuals revealed two deep-rooted subclades: R8a and R8b. Furthermore, these subclades split into several fine subclades. An isofrequency contour map detected the highest frequency of R8 in the state of Orissa. Spearman's rank correlation analysis suggests significant correlation of R8 occurrence with geography.The coalescent age of newly-characterized subclades of R8, R8a (15.4+/-7.2 Kya) and R8b (25.7+/-10.2 Kya) indicates that the initial maternal colonization of this haplogroup occurred during the middle and upper Paleolithic period, roughly around 40 to 45 Kya. These results signify that the southern part of Orissa currently inhabited by Munda speakers is likely the origin of these autochthonous maternal deep-rooted haplogroups. Our high-resolution study on the genesis of R8 haplogroup provides ample evidence of its deep-rooted ancestry among the Orissa (Austro-Asiatic) tribes
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