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71.
Indoor wireless communication systems experience deep multipath fading due to the presence of people, antenna movement, and other environmental factors. The objective of this paper is to present results concerning envelope fading and large-scale attenuation properties of the signal based on narrowband measurements carried out at 21.6 and 37.2 GHz with and without antenna diversity. By using various transmitter-receiver arrangements in measurements which were taken over one floor of a university building, envelope statistics of received signal are produced with and without antenna diversity. It is shown that the statistical distributions follow the Rayleigh curve and hence a diversity gain close to 10 dB can be obtained for an availability of 99%. Power law exponents and wall loss factors are also calculated to assist in the design of future indoor radio systems in the millimeter frequency range 相似文献
72.
PW Kalivas 《Canadian Metallurgical Quarterly》1994,114(1):175-180
The administration of neurotensin into the ventral tegmental area stimulates dopamine neurons and locomotor activity. Furthermore, when neurotensin is microinjected daily into the ventral tegmental area the motor stimulant response increases. The role of protein kinases in the motor stimulant effect of neurotensin was evaluated by coadministration of the protein kinase inhibitors H8 and H7 into the ventral tegmental area with neurotensin. It was found that the acute motor stimulant effect of neurotensin was abolished in a dose-dependent fashion by H8 coadministration. Neurotensin-induced activity was also blocked by H7. However, acute motor stimulation following microinjection of the mu opioid, Tyr-d-Ala-Gly-MePhe-Gly(ol) or the potassium channel antagonist apamin into the ventral tegmental area was not affected by coadministration with H8. The behavioral sensitization produced by daily neurotensin microinjection into the ventral tegmental area was also prevented by the coadministration of H8. These data indicate that the motor stimulation produced by acute and repeated neurotensin microinjection into the ventral tegmental area is dependent upon activation of protein kinase(s). Furthermore, Tyr-d-Ala-Gly-MePhe-Gly(ol) and apamine elicit locomotion independently of protein kinase(s). 相似文献
73.
N. Kalivas L. Costaridou I. Kandarakis D. Cavouras C. D. Nomicos G. Panayiotakis 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2002,490(3):614-629
The noise properties of granular phosphors used in X-ray imaging detectors are studied in terms of a noise transfer function, NTF. This study is performed in high-exposure conditions where the contribution of structure noise to total screen noise is considerable. An analytical model, based on the cascaded linear systems methodology presented in the literature, is developed. This model takes into account the quantum noise and structure noise. Furthermore, it considers the effect of the K X-rays reabsorption on the phosphor material and the effect of screen thickness on the NTF. The model was validated against experimental results obtained by a set of Zn2SiO4:Mn phosphor screens prepared by sedimentation. The model may be used to evaluate the effect of screen thickness and the effect of the characteristic X-rays on NTF in high-exposure conditions where structure noise is considerable. 相似文献
74.
N. Kalivas I. Kandarakis D. Cavouras L. Costaridou C. D. Nomicos G. Panayiotakis 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》1999,430(2-3)
The noise properties of the granular phosphor screens, which are utilized in X-ray imaging detectors, are studied in terms of the quantum noise transfer function (QNTF). An analytical model, taking into account the effect of K-characteristic X-rays reabsorption within the phosphor material and the optical properties of the phosphor, was developed. The optical properties of the phosphor material required by the model were obtained from literature, except for the optical diffusion length (σ) that was determined by data fitting and was found to be 26 cm2/g. The deviation between theoretical and experimental data is σ depended. Specifically for σ=26 cm2/g and σ=25 cm2/g the respective deviations between experimental and predicted results were 0.698% and −1.597%. However for relative differences in σ more than 15% from the value 26 cm2/g, the corresponding deviations exceed by 6 times the value of 0.698%. The model was tested via comparison to experimental results obtained by a set of Y2O3:Eu3+ phosphor screens prepared by sedimentation. The model may be used to evaluate the effect of screen thickness and irradiation geometry on quantum noise of phosphor materials for transmission and reflection mode. 相似文献
75.
76.
Fotis Plessas Athanasios Tsitouras Grigorios Kalivas 《International Journal of Circuit Theory and Applications》2011,39(7):791-800
In this work we present a detailed study of the phase noise of subharmonic injection locked oscillators (s‐ILOs). A new simple and efficient model has been presented for accurately predicting the phase noise of a microwave s‐ILO. The validity of the analytical technique is verified with measurement results obtained from a 5‐GHz fully differential Colpitts‐based s‐ILO. The results showed that a phase noise improvement of 12 dB at 1 kHz offset frequency compared to the free‐running case can be achieved, whereas the power consumption is 21 mW. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
77.
Boukouvala E Antonopoulou E Favre-Krey L Diez A Bautista JM Leaver MJ Tocher DR Krey G 《Lipids》2004,39(11):1085-1092
Peroxisome proliferator-activated receptors (PPAR) are nuclear hormone receptors that control the expression of genes involved
in lipid homeostasis in mammals. We searched for PPAR in sea bass, a marine fish of particular interest to aquaculture, after
hypothesizing that the physiological and molecular processes that regulate lipid metabolism in fish are similar to those in
mammals. Here, we report the identification of complementary DNA and corresponding genomic sequences that encode three distinct
PPAR from sea bass. The sea bass PPAR are the structural homologs of the mammalian PPARα, β/δ and γ isotypes. As revealed
by RNase protection, the tissue expression profile of the fish PPAR appears to be very similar to that of the mammalian PPAR
homologs. Thus, PPARα is mainly expressed in the liver, PPARγ in adipose tissue, and PPARβ in all tissues tested, with its
highest levels in the liver, where it is also the dominant isotype expressed. Like mammalian PPAR, the sea bass isotypes recognize
and bind to PPAR response elements of both mammalian and piscine origin, as heterodimers with the 9-cis retinoic acid receptor. Through the coactivator-dependent receptor ligand assay, we also demonstrated that natural FA and
synthetic hypolipidemic compounds can act as ligands of the sea bass PPARα and β isotypes. This suggests that the sea bass
PPAR act through similar mechanisms and perform the same critical lipid metabolism functions as mammalian PPAR. 相似文献
78.
Recent work has shown that ridge regression (RR) is Pareto to partial least squares (PLS) and principal component regression (PCR) when the variance indicator Euclidian norm of the regression coefficients, //p//, is plotted against the bias indicator root mean square error of calibration (RMSEC). Simplex optimization demonstrates that RR is Pareto for several other spectral data sets when //p// is used with RMSEC and the root mean square error of evaluation (RMSEE) as optimization criteria. From this investigation, it was observed that while RR is Pareto optimal, PLS and PCR harmonious models are near equivalent to harmonious RR models. Additionally, it was found that RR is Pareto robust, i.e., models formed at one temperature were then used to predict samples at another temperature. Wavelength selection is commonly performed to improve analysis results such that bias indicators RMSEC, RMSEE, root mean square error of validation, or root mean square error of cross-validation decrease using a subset of wavelengths. Just as critical to an analysis of selected wavelengths is an assessment of variance. Using wavelengths deemed optimal in a previous study, this paper reports on the variance/bias tradeoff. An approach that forms the Pareto model with a Pareto wavelength subset is suggested. 相似文献
79.
Grigorios Loukides Aris Gkoulalas-Divanis Bradley Malin 《Knowledge and Information Systems》2011,28(2):251-282
Publishing transactional data about individuals in an anonymous form is increasingly required by organizations. Recent approaches
ensure that potentially identifying information cannot be used to link published transactions to individuals’ identities.
However, these approaches are inadequate to anonymize data that is both protected and practically useful in applications because
they incorporate coarse privacy requirements, do not integrate utility requirements, and tend to explore a small portion of
the solution space. In this paper, we propose the first approach for anonymizing transactional data under application-specific
privacy and utility requirements. We model such requirements as constraints, investigate how these constraints can be specified,
and propose COnstraint-based Anonymization of Transactions, an algorithm that anonymizes transactions using a flexible anonymization
scheme to meet the specified constraints. Experiments with benchmark datasets verify that COAT significantly outperforms the
current state-of-the-art algorithm in terms of data utility, while being comparable in terms of efficiency. Our approach is
also shown to be effective in preserving both privacy and utility in a real-world scenario that requires disseminating patients’
information. 相似文献
80.
Grigorios G. Chrysos Epameinondas Antonakos Patrick Snape Akshay Asthana Stefanos Zafeiriou 《International Journal of Computer Vision》2018,126(2-4):198-232
Recently, technologies such as face detection, facial landmark localisation and face recognition and verification have matured enough to provide effective and efficient solutions for imagery captured under arbitrary conditions (referred to as “in-the-wild”). This is partially attributed to the fact that comprehensive “in-the-wild” benchmarks have been developed for face detection, landmark localisation and recognition/verification. A very important technology that has not been thoroughly evaluated yet is deformable face tracking “in-the-wild”. Until now, the performance has mainly been assessed qualitatively by visually assessing the result of a deformable face tracking technology on short videos. In this paper, we perform the first, to the best of our knowledge, thorough evaluation of state-of-the-art deformable face tracking pipelines using the recently introduced 300 VW benchmark. We evaluate many different architectures focusing mainly on the task of on-line deformable face tracking. In particular, we compare the following general strategies: (a) generic face detection plus generic facial landmark localisation, (b) generic model free tracking plus generic facial landmark localisation, as well as (c) hybrid approaches using state-of-the-art face detection, model free tracking and facial landmark localisation technologies. Our evaluation reveals future avenues for further research on the topic. 相似文献