1,241 research outputs found

    Implications of a Quantum Mechanical Treatment of the Universe

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    We attempt to treat the very early Universe according to quantum mechanics. Identifying the scale factor of the Universe with the width of the wave packet associated with it, we show that there cannot be an initial singularity and that the Universe expands. Invoking the correspondence principle, we obtain the scale factor of the Universe and demonstrate that the causality problem of the standard model is solved.Comment: LaTex, 5 pages, 1 figure, to be published in Mod. Phys. Lett.

    UTILIZATION OF FOUR SUDANESE WILD FRUITS TO PRODUCE NECTARS

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    Doum (Hyphaene thebaica L), kirkir (Randia geipaeflora), karmadoda (Naucleae latifolia) and godeim (Grewia tenax) are some of the indigenous fruits in Sudan. The aim of this investigation is to process nectars from the edible part of these fruits. Doum and kirkir fruits were soaked in water in variable ratios for different durations of time to obtain the highest total soluble solids, total solids and total extractable matter. The pulps of karmadoda and godeim fruits were obtained mechanically by adding water, blanching and pulping with pulper machine. Results showed that soaking of doum and kirkir fruits at ratios 1: 4/2 h and 1: 4/8 h, respectively, were the most appropriate methods for extraction. The total solids (TS) obtained were 10.61 and 10.32 %, total soluble solids (TSS) 10.50 and 9.50%, and the total extractable matters (TEM) were 26.06 and 23.69%, respectively. However, blanching karmadoda fruit in water at a ratio of 1: 2/10 min gave total solids of 5.63% and total soluble solids of 5.00%. The nectars made were subjected to organoleptic evaluation. The results suggested that processing of nectars from forest fruits by direct extraction gave excellent sensory characteristics for human consumption

    A New Design for Compact Size Wireless Power Transfer Applications Using Spiral Defected Ground Structures

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    In this article, a new wireless power transfer (WPT) design is proposed for improving the efficient of system. The suggested system contains two spiral defected ground structure (DGS) resonators coupled back-to-back. The spiral DGS alone acts as band stop filter (BSF), and when the two resonators are coupled back-to-back, a BSF is emerged leading to WPT system. The DGS resonators are loaded through chip capacitors for miniaturization. The proposed structures are fabricated and tested. The proposed system has a highest efficiency of 97.7% at a transmission distance of 10 mm which is suitable for biomedical applications. Both simulated and experimental results are in good concurrence

    The organophosphate pesticide chlorpyrifos affects form deprivation myopia

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    PURPOSE. The effects of the anticholinesterase organophosphate pesticide chlorpyrifos (CPF) on the refractive development of the eye were examined. Form deprivation was used to induce eye growth to address the previously reported relationship between organophosphate pesticide use and the incidence of myopia. METHODS. Chickens, a well-established animal model for experimental myopia and organophosphate neurotoxicity, were dosed with chlorpyrifos (3 mg/kg per day, orally, from day 2 to day 9 after hatching) or corn oil vehicle (VEH) with or without monocular form deprivation (MFD) over the same period. The set of dependent measures included the refractive state of each eye measured using retinoscopy, axial dimensions determined with A-scan ultrasound, and intraocular pressure. RESULTS. Dosing with CPF yielded an inhibition of 35% butyrylcholinesterase in plasma and 45% acetylcholinesterase in brain. MFD resulted in a significant degree of myopia in form-deprived eyes resulting from significant lengthening of the vitreal chamber of the eye. CPF significantly reduced the effect of MFD, resulting in less myopic eyes (mean refraction: VEH-MFD = -16.2 ± 2.3 diopters; CPF-MFD = - 11.1 ± 1.8 diopters) with significantly shorter vitreal chambers. Nonoccluded eyes were, on average, slightly hyperopic. Treatment with CPF for 1 week in the absence of MFD led to no significant change in ocular dimensions or refraction relative to controls. CONCLUSIONS. The use of form deprivation as a challenge suggests that CPF treatment interferes with the visual regulation of eye growth

    Compact Size Triple Notched-bands UWB Antenna with Sharp Band-Rejection Characteristics at WiMAX and WLAN Bands

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    In this paper, a compact triple band-notched Ultra Wideband (UWB) antenna with sharp band-elimination features and controlled notched bandwidths is proposed and discussed. The design is made up of a rectangular-shaped   patch UWB planar monopole antenna with double collections of band-notched configurations. The band-notched configurations are involved to produce the desired lower and upper stop bands with good frequency selectivity and suitable stop bandwidths. The first notch is realized by using a C-shaped slot etched in the radiating patch in order to eliminate the interference at the WiMAX (3.4 - 3.8 GHz) applications. The second and the third notches are realized together by using a pair of U-shaped resonators that are located beside the feed line in both sides to eliminate the interference with the lower WLAN (5.15–5.35 GHz) and the higher WLAN (5.725–5.825GHz) bands.  Additionally, the bandwidths of the lower and upper stop bands can be control separately by changing the parameters of the band-notched configurations. Furthermore, the suggested triple notched bands UWB antenna is optimized, fabricated, and measured for verification purposes. The measured results are close to the simulated ones

    Sinteza i protuupalno, analgetsko i ulcerogeno djelovanje derivata tieno[2,3-d]pirimidina

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    5-Methyl-6-phenyl-2-thioxothieno[2,3-d]pyrimidone derivative (2) reacted with hydrazonoyl chloride derivatives to afford triazolothienopyrimidones 4a-f. Also, acetone-1-(2-amino-5-isopropyl-thiophene-3-carbonitrile) (3) reacted with functional and bifunctional groups to yield the corresponding compounds 5-11. The new products showed anti-inflammatory, analgesic, and ulcerogenic activities comparable to that of indomethacin and acetylsalicylic acid, respectively.Reakcijom derivata 5-metil-6-fenil-2-tioksotieno[2,3-d]pirimidona (2) s hidrazonoil kloridima dobiveni su triazolotienopirimidoni 4a-f, a reakcijom aceton-1-(2-amino-5-izopropil-tiopen-3-karbonitrila (3) s funkcionalnim i bifunkcionalnim spojevima dobiveni su produkti 511. Novi spojevi imaju slično protuupalno, analgetsko i ulcerogeno djelovanje kao i indometacin, odnosno acetilsalicilna kiselina

    Fate of the Universe, Age of the Universe, Dark Matter, and the Decaying Vacuum Energy

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    It is shown that in the cosmological models based on a vacuum energy decaying as a^{-2}, where a is the scale factor of the universe, the fate of the universe in regard to whether it will collapse in future or expand forever is determined not by the curvature constant k but by an effective curvature constant k_{eff}. It is argued that a closed universe with k=1 may expand forever, in other words simulate the expansion dynamics of a flat or an open universe because of the possibility that k_{eff}=0 or -1, respectively. Two such models, in one of which the vacuum does not interact with matter and in another of which it does, are studied. It is shown that the vacuum equation of state p_{vac}= -\rho_{vac} may be realized in a decaying vacuum cosmology provided the vacuum interacts wuth matter. The optical depths for gravitational lensing as a function of the matter density and other parameters in the models are calculated at a source redshift of 2. The age of the universe is discussed and shown to be compatible with the new Hipparcos lower limit of 11Gyr. The possibility that a time-varying vacuum energy may serve as dark matter is suggested.Comment: AAS LaTex, 29 pages, published in the Astrophysical Journal, 520, 45, 199

    A Hybrid NLMS/RLS Algorithm to Enhance the Beamforming Process of Smart Antenna Systems

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    Adaptive beamforming algorithm is a signal processing technique used by smart antenna system to steer the main beam toward the desired signal direction and cancel the interfering signals of other directions. This paper proposes a hybrid non-blind beamforming algorithm that combines the Normalized Least Mean Square (NLMS) algorithm and the Recursive Least Square (RLS) algorithm to exploit the advantages of both algorithms and avoid their drawbacks. The hybrid NLMS/RLS algorithm solves many problems of the other non-blind algorithms. A comparative study between the proposed algorithm and other non-blind beamforming algorithms is introduced to illustrate the points of strength of the proposed algorithm. The hybrid NLMS/RLS algorithm is applied to different types of patch array antenna with resonance frequency 10GHz to demonstrate the performance of the proposed algorithm to each array antenna type
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