1,807 research outputs found
Mixed Non-Uniform Width / Evanescent Mode Ceramic Resonator Waveguide Filter With Wide Spurious Free Bandwidth
This paper presents a method to improve the spurious performance of integrated ceramic waveguide filters. Nonuniform width ceramic waveguide resonator and evanescent mode ceramic resonators are employed together to the resonant frequencies of higher order modes. The proposed designs give 75% improvement in stop band response when compared to uniform width ceramic waveguide filter. Simulated results of two six pole chebyshev filters are presented here with improved stop band performance
Social status modulates prosocial behavior and egalitarianism in preschool children and adults
Humans are a cooperative species, capable of altruism and the creation of shared norms that ensure fairness in society. However, individuals with different educational, cultural, economic, or ethnic backgrounds differ in their levels of social investment and endorsement of egalitarian values. We present four experiments showing that subtle cues to social status (i.e., prestige and reputation in the eyes of others) modulate prosocial orientation. The experiments found that individuals who experienced low status showed more communal and prosocial behavior, and endorsed more egalitarian life goals and values compared with those who experienced high status. Behavioral differences across high- and low-status positions appeared early in human ontogeny (4-5 y of age)
Investigation of photo-catalytic activity of Zn1−xCo x S nanocrystals using methylene blue dye as test contaminant
Clinical Thermoradiotherapy
A clinical trial is currently in progress to determine the efficacy of combined fractions of hyperthermia and radiation. The protocol consists of two parts. First, four fractions of microwave-induced hyperthermia (45.0° ± 0.5°C) are applied for 1 1/2 hours to the volume encompassing the tumor, each separated by 72 hours. After a one-week rest, a second series of four fractions is administered again at 72- hour intervals. Each fraction consists of a 400 rad dose of radiation followed within 20 minutes by hyperthermia (42.5 ± 0.5°C) for 1 1/2 hours. Currently, we have treated 62 patients with 82 fields with a mean follow-up time of six months to date. Total regression was observed in 60% of all cases, and partial regression in 33%; no response was seen in only 6% of all those treated. Five local and three marginal recurrences have been observed. This paper discusses details of response based on site, histology, and classification
High sensitivity and multifunctional micro-Hall sensors fabricated using InAlSb/InAsSb/InAlSb heterostructures
Further diversification of Hall sensor technology requires development of materials with high electron mobility and an ultrathin conducting layer very close to the material's surface. Here, we describe the magnetoresistive properties of micro-Hall devices fabricated using InAlSb/InAsSb/InAlSb heterostructures where electrical conduction was confined to a 30 nm-InAsSb two-dimensional electron gas layer. The 300 K electron mobility and sheet carrier concentration were 36 500 cm(2) V-1 s(-1) and 2.5 x 10(11) cm(-2), respectively. The maximum current-related sensitivity was 2 750 V A(-1) T-1, which was about an order of magnitude greater than AlGaAs/InGaAs pseudomorphic heterostructures devices. Photolithography was used to fabricate 1 mu m x 1 mu m Hall probes, which were installed into a scanning Hall probe microscope and used to image the surface of a hard disk
Elemental Analysis of Nanomaterial Using Photon-Atom Interaction Based EDXRF Technique
Presence of trace amount of foreign impurities (both metallic and non-metallic) in standard salts used for sample preparation and during the synthesis process can alter the physical and chemical behavior of the pure and doped nano-materials. Therefore, it becomes important to determine concentration of various elements present in synthesized nano-material sample. In present work, the elemental and compositional analysis of nano-materials synthesized using various methods has been performed using photon-atom interaction based energy dispersive x-ray fluorescence (EDXRF) technique. This technique due to its multielement analytical capability, lower detection limit, capability to analyze metals and non-metals alike and almost no sample preparation requirements can be utilized for analysis of nano-materials. The EDXRF spectrometer involves a 2.4 kW Mo anode x-ray tube (Pananalytic, Netherland) equipped with selective absorbers as an excitation source and an LEGe detector (FWHM = 150 eV at 5.895 keV, Canberra, US) coupled with PC based multichannel analyzer used to collect the fluorescent x-ray spectra. The analytical results showed good agreements with the expected values calculated on the basis of the precursor used in preparation of nano-materials
Photoluminescence and Photo-catalytic Activity of Synthesized Nanocrystals
Intrinsic and extrinsic semiconductor nanostructures have attracted great attention due to their size tunable photo-physical and photo-chemical properties. In the present paper, polyvinyl pyrrolidone (PVP) capped Zn1-xEuxS (0.00001≤x≤0.1)nanocrystals have been synthesized by means of a facile chemical synthesis method. Crystallography and morphology of synthesized materials have been deliberated using X-ray diffraction (XRD) and transmission electron microscope (TEM), respectively. Diffraction and electron micrograph studies reveal that the synthesized materials are zinc blende nanocrystals having average particle size ~3nm. Elemental and compositional analyses of the nanocrystals have been done using energy dispersive X-ray fluorescence (EDXRF) technique. Steady state photoluminescence spectra have been recorded for optical characterization of synthesized nanomaterials. Photo-catalytic activity potential of synthesized nanomaterials under UV radiation exposure has been investigated using methylene blue (MB) dye as a test contaminant in aqueous media. Photo-physical and photo-chemical behaviour dependence on doping concentration has been described in detail. Moreover, the sophistication of competition between charge carrier recombination and charge carrier trapping followed by the competition between recombination of trapped carriers and interfacial charge transfer processes have been presented in a fantastic and elaborative way by comparative study of photoluminescence and photo-catalytic activity results
Parallax of PSR J1744-1134 and the Local Interstellar Medium
We present the annual trigonometric parallax of PSR J1744-1134 derived from
an analysis of pulse times of arrival. The measured parallax, pi = 2.8+/-0.3
mas ranks among the most precisely determined distances to any pulsar. The
parallax distance of 357+/-39 pc is over twice that derived from the dispersion
measure using the Taylor & Cordes model for the Galactic electron distribution.
The mean electron density in the path to the pulsar, n_e = (0.0088 +/- 0.0009)
cm^{-3}, is the lowest for any disk pulsar. We have compared the n_e for PSR
J1744-1134 with those for another 11 nearby pulsars with independent distance
estimates. We conclude that there is a striking asymmetry in the distribution
of electrons in the local interstellar medium. The electron column densities
for pulsars in the third Galactic quadrant are found to be systematically
higher than for those in the first. The former correlate with the position of
the well known local HI cavity in quadrant three. The excess electrons within
the cavity may be in the form of HII clouds marking a region of interaction
between the local hot bubble and a nearby superbubble.Comment: revised version accepted for publication in ApJ Letters; reanalysis
of uncertainty in parallax measure and changes to fig
Manipulation of the Spin Memory of Electrons in n-GaAs
We report on the optical manipulation of the electron spin relaxation time in
a GaAs based heterostructure. Experimental and theoretical study shows that the
average electron spin relaxes through hyperfine interaction with the lattice
nuclei, and that the rate can be controlled by the electron-electron
interactions. This time has been changed from 300 ns down to 5 ns by variation
of the laser frequency. This modification originates in the optically induced
depletion of n-GaAs layer
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