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1.
INTRODUCTION: Parvovirus B19 infection is frequent. Primary infection leads to diverse skin manifestations including the recently described gloves-and-socks papulopurpura. CASE REPORT: A patient presented with a papulopurpuric eruption on the nose, hands, feet and perineum with cheilitis and high-grade fever. Parvovirus B19 serology showed characteristic IgG on the 15th day after the initial eruption demonstrating the seroconversion. Cold agglutinins were positive during the eruption and negative after regression. DISCUSSION: The gloves-and-socks papulopurpura syndrome was initially described in 1990. Since that time 20 cases have been reported. In 7 cases, primary parvovirus B19 infection was proven and viral infections were suspected in the others (measles, coxsackie B6, hepatitis B, Epstein-Barr virus). Our case evidenced here to undescribed skin manifestations and the development of cold agglutinins. The presence of cold agglutinins at eruption could explain the acral localizations observed in this syndrome.  相似文献   
2.
We analyze and numerically study the code-matching logic module that is the central element in a proposed soliton-based ring network system running at peak rates of 100 Gb/s. The proposed network is packet-switched, and fast logic is required to route each packet. That is the function of the code-matching logic module, and four soliton logic gates that can perform fast logic are the key devices in its design. The behavior of the code-matching logic module is governed by a large set of parameters, and we simulate it by varying many of these parameters. The physical effects that occur in these devices and their significance are analyzed. The results indicate that the logic module will work but within a restricted parameter range  相似文献   
3.
Seasonal changes in the ultrastructure of the free-living Rose-Ringed Parakeet Psittacula krameri pineal were examined in relation to the sub-tropical environment and seasonal reproduction. Dark and light pinealocytes of the presumptive neuroendocrine cell line predominated, while supporting cells, ependymal cells, myelinated and non-myelinated nerve fibers with nerve endings, and regressed photoreceptor elements were also observed. Unlike in pineals of many animals, particularly mammals, the presence of dense-core vesicles (DCVs) with varying core density, and absence of clear vesicles and vacuoles with flocullent material, indicate the involvement of DCVs in the synthesis and secretion of pineals principle/s. In November (pre-breeding) when the day length registered a drop to LD 10:14, pinealocytes showed significantly decreased and smaller DCVs and mitochondria, nuclei with heterochromatin, and greater distribution of glycogen and lipid droplets, all indicating low pineal metabolic activity. During the shortest day regime from December to March, when the birds peaked breeding, the number and size of DCVs and mitochondria increased, and Golgi body-endoplasmic reticulum-lysosome complex (GERL) was very well defined. Images of DCVs suggested possible secretion of pineal principle/s by dissolution, and exocytosis. Coincidence of these features with peak gonadotrophic (circulating LH) and spermatogenic and testicular endocrine activity described previously suggested an active turnover of pineal products during this short day length regime when parakeets breed. In contrast, during the post-breeding season (April onwards), when the day-length increased to LD 13:11 and hypophyseal-gonadal function was down, nuclei and RER continued to show active profile, the Golgi body and associated complex were moderately seen, and the DCVs and mitochondria were significantly smaller and lesser. It is therefore probable that the pineal is an important relay to translate cues related to less drastic sub-tropical environmental change into DCV-linked neurohormones that in turn may be involved in modulating seasonal breeding in parakeets.  相似文献   
4.
The behavior of small cracks growing out of the roots of blunt notches in compact type specimens of an austenitic steel was characterized under fatigue loading in wet H 2 plus air environment. The growth rates of cracks in the size range of 0.125 mm to 0.75 mm were up to two orders of magnitude higher than the rates expected for conventional cracks at equal stress intensity range, K. It was also observed that the small cracks grew at these fast rates only in corrosive environments when the loading frequency was 0.02 Hz or less. At a frequency of 10 Hz, the behavior was in agreement with the trend predicted for conventional size cracks.The above observations are rationalized in terms of the breakdown of the concept of a single parameter representation of the crack tip stress and strain field by K or in terms of differences in crack tip environments between small and long cracks for the same bulk environment. A simple engineering model is proposed which adequately represents the observed small crack growth behavior.
Résumé On a procédé à la caractérisation, sous charges de fatigue en atmosphère humide de H 2 et d'air, de petites fissures se développant à partir des racines d'entailles arrondies dans des éprouvettes compactes.Les vitesses de croissance des fissures d'une taille allant de 0,125 à 0,750 mm se sont révélé être de deux ordres de grandeur plus grandes que les vitesses prévues dans le cas de fissures conventionnelle, soumises aux mêmes variations de l'intensité de contrainte K. On a également observé que de petites fissures croissaient à ces grandes vitesses seulement dans des atmosphères corrosives, lorsque la fréquence de sollicitation était de 0,02 Hz ou moins. A la fréquence de 10 Hz, le comportement observé s'est trouvé en accord avec les tendances prévues pour des fissures de taille conventionnelle.Les observations ci-dessus sont rationnalisées en un élargissement du concept de représentation monoparamétrique par le facteur K du champ de contraintes et de dilatation à l'extrémité de la fissure, ou en termes des différences rencontrées dans l'environnement local de l'extrémité d'une fissure, selon que celle-ci est longue ou courte, et ce dans un même environnement global.On propose un modèle simple utilisable en pratique, pour représenter de manière adéquate le comportement à la croissance observé pour des petites fissures.


Metallurgy Department  相似文献   
5.
The polarographic behaviour of diisopropylaminoethanethiol HCl (RSH) has been studied in presence of 0·1 M LiCl at the dme. The effects of pH, supporting electrolyte, concentration, drop time and temperature on the characteristics of the wave have been investigated. The curves consist of two waves—a small pre-wave followed by a normal anodic wave over the entire pH range (2·60–12·60). The maximum number of moles absorbed on unit area is 3·98 × 10?10 mole/cm2, ie 2·4 × 1014 molecules/cm2, which corresponds to an area 41·6 Å2 per adsorbed molecule. The adsorption coefficient and molar adsorption energy are 6·34 × 102 and 26·34 kcal/mole respectively. The electrode reaction is reversible, diffusion-controlled and involves a one-electron tranfer process. The pK of the ?SH group is 10·6. Controlled-potential electrolysis, interaction with mercuric chloride and mathematical analysis reveal the depolarization of mercury with the formation of a Hg(I) complex, mercurous mercaptide RSHg, which rapidly changes to more stable mercuric complex (RS)2Hg.  相似文献   
6.
In this paper a linear time algorithm is proposed for preprocessing the edges of a graph. After preprocessing (in linear time), the fundamental cut set of any tree edge can be determined in time proportional to the size of that cut set.  相似文献   
7.
Low Cycle Fatigue (LCF) on smooth hour glass specimens and Fatigue Crack Propagation (FCP) studies on Single Edge Notch (SEN) specimens were carried out at room temperature on four Cu-Al polycrystalline alloys to investigate the effects of Stacking Fault Energy (SFE) and mechanical property variations on fatigue characteristics. Significant improvements in fatigue properties were observed for alloys of low SFE. A microhardness technique was used to delineate the fatigue plastic zone ahead of stopped cracks at several stress intensity ranges for all the alloys. Planar slip was associated with a less than a second power dependence of plastic zone size on the stress intensity range. Transmission Electron Microscopy (TEM) was used to observe the substructures that developed both in LCF at different strain ranges and also ahead of fatigue cracks at different stress intensity ranges. Fractography was carried out to study the micromechanisms of crack propagation using a two stage replication technique. The experimental results were in good agreement with a theoretical model for FCP developed previously by the authors which incorporates mechanical and microstructural variables.  相似文献   
8.
Introducing Machine-to-Machine (M2M) communications over traditional 4G cellular networks make the cellular random access channel more congested and collision-prone. In order to resolve this random access congestion, we propose RoBiN - Random access using Border router in M2M cellular Networks. RoBiN proposes an architectural modification of introducing small cells, called Border Routers (BR), in cellular networks, with complete frequency reuse capability. We formulate the aforementioned challenge in terms of collision probability and system capacity. Subsequently, we propose an efficient solution for M2M communications in cellular networks. Exhaustive mathematical analysis shows that RoBiN significantly improves the random access success probability, by 50 % over existing 4G cellular systems. Simulation results on typical 4G networks corroborate our mathematical analysis and demonstrate almost 15 dB increase in Signal-to-Interference-plus-Noise Ratio (SINR) and 3 times throughput improvements over legacy 4G cellular systems. Furthermore, RoBiN also achieves 50 %?80 % improvement in collision probability over existing time alignment matching work.  相似文献   
9.
In order to meet the growing demand for mobile multimedia broadcast services 3GPP includes evolved multimedia broadcast and multicast (eMBMS) services in LTE systems. The high data rates, low latency and QoS provisioning makes LTE systems more suitable for mobile broadcast and multicast services than legacy wireless networks. However, the 3GPP standards has not specified any scheduling strategy for this broadcast and multicast services. In this paper, we propose a novel eMBMS scheduling technique (NEST) which focuses on reducing the average waiting time (latency) of the broadcast services offered by LTE system. This paper has twofold contributions. We proffer NEST considering two types of impatience that is user equipment (UE) departure and UE request repetition. Our proposed scheduling strategy estimates the effects originating from the departure of the mobile UEs and UE request repetition case. It intelligently combines the advantages of both flat scheduling and on-demand scheduling in such a way that the overall latency of the system is reduced. We design a suitable modeling framework to analyze the performance of the system. Simulation experiments on typical LTE systems support the performance analysis and demonstrates 10 % gains while comparing with existing eMBMS scheduling available in present LTE systems.  相似文献   
10.
A method of optimal beamforming for flat Rayleigh faded channels using the Fractional Fourier Transform (FRFT) is considered in this paper. It has been demonstrated through simulations that optimal beamforming with FRFT allows smaller mean-square errors in restoring signals degraded with linear time-or frequency variant distortions and Additive White Gaussian Noise. This is made possible by the additional flexibility that comes with free parameter ‘a’ of the fractional Fourier transform as oppose to the classical Fourier transform (FT). The method is especially useful in moving source problems, where Doppler Effect produces frequency shift when the source is moving, as in mobile and wireless communication where user produces the frequency shift while moving. In this paper it is shown through simulations that beamforming in fractional domain reduces BER as compared to time or frequency domain.  相似文献   
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