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41.
Cianca E. Prasad R. De Sanctis M. De Luise A. Antonini M. Teotino D. Ruggieri M. 《Communications Magazine, IEEE》2005,43(12):supl.33-supl.39
Thus far, high-altitude platform (HAP)-based systems have been mainly conceived as an alternative to satellites for complementing the terrestrial network. This article aims to show that HAP should no longer be seen as a competitor technology by investors of satellites, but as a key element for an efficient hybrid terrestrial-satellite communication system. Two integrated HAP-satellite scenarios are presented, in which the HAP is used to overcome some of the shortcomings of satellite-based communications. Moreover, it is shown that the integration of HAPs with satellite systems can be used to provide more efficient fleet-management and traffic-control services and more powerful data-relay systems. 相似文献
42.
The European Patent Convention as revised in 2000 (EPC 2000) [1] entered into force on 13 December 2007. While the revision changed rather little in terms of substantive patent law, it did change procedural practice compared to the EPC in force before, drafted in 1973. This article looks at some key features of the European patent grant and post-grant procedures that either have changed fundamentally or have been newly introduced, and their effect on patent document collections. 相似文献
43.
Carla Vaz Ferreira Débora Rodrigues Siqueira Mírian Romitti Lucieli Ceolin Beatriz Assis Brasil Luise Meurer Clarissa Capp Ana Luiza Maia 《International journal of molecular sciences》2014,15(4):5323-5336
Pheochromocytoma (PHEO), a rare catecholamine producing tumor arising from the chromaffin cells, may occurs sporadically (76%–80%) or as part of inherited syndromes (20%–24%). Angiogenesis is a fundamental step in tumor proliferation and vascular endothelial growth factor (VEGF-A) is the most well-characterized angiogenic factor. The role of angiogenic markers in PHEO is not fully understood; investigations were therefore made to evaluate the expression of VEGF-A and its receptors in PHEO and correlate to clinical parameters. Twenty-nine samples of PHEO were evaluated for VEGF-A, VEGF receptor-1 (VEGFR-1) VEGFR-2 expression and microvessel density (MVD) by immunohistochemistry. Clinical data were reviewed in medical records. The mean age of patients was 38 ± 14 years, and 69% were woman. VEGF-A, VEGFR-1 and VEGFR-2 staining were detected in nearly all PHEO samples. No significant correlation was observed between VEGF-A, VEGFR-1, VEGFR-2 expression or MVD and age at diagnosis, tumor size or sporadic and hereditary PHEO. However, the levels of expression of these molecules were significantly higher in malignant PHEO samples (p = 0.027, p = 0.003 and p = 0.026, respectively).VEGF-A and its receptors were shown to be up-regulated in malignant PHEO, suggesting that these molecules might be considered as therapeutic targets for unresectable or metastatic tumors. 相似文献
44.
Elke Persch Dr. Steve Bryson Dr. Nickolay K. Todoroff Dr. Christian Eberle Jonas Thelemann Natalie Dirdjaja Dr. Marcel Kaiser Maria Weber Hassan Derbani Prof. Dr. Reto Brun Prof. Dr. Gisbert Schneider Prof. Dr. Emil F. Pai Prof. Dr. R. Luise Krauth‐Siegel Prof. Dr. François Diederich 《ChemMedChem》2014,9(8):1880-1891
The causative agents of the parasitic disease human African trypanosomiasis belong to the family of trypanosomatids. These parasitic protozoa exhibit a unique thiol redox metabolism that is based on the flavoenzyme trypanothione reductase (TR). TR was identified as a potential drug target and features a large active site that allows a multitude of possible ligand orientations, which renders rational structure‐based inhibitor design highly challenging. Herein we describe the synthesis, binding properties, and kinetic analysis of a new series of small‐molecule inhibitors of TR. The conjunction of biological activities, mutation studies, and virtual ligand docking simulations led to the prediction of a binding mode that was confirmed by crystal structure analysis. The crystal structures revealed that the ligands bind to the hydrophobic wall of the so‐called “mepacrine binding site”. The binding conformation and potency of the inhibitors varied for TR from Trypanosoma brucei and T. cruzi. 相似文献
45.
Felix M. Wunner Marie‐Luise Wille Thomas G. Noonan Onur Bas Paul D. Dalton Elena M. De‐Juan‐Pardo Dietmar W. Hutmacher 《Advanced materials (Deerfield Beach, Fla.)》2018,30(20)
The additive manufacturing of highly ordered, micrometer‐scale scaffolds is at the forefront of tissue engineering and regenerative medicine research. The fabrication of scaffolds for the regeneration of larger tissue volumes, in particular, remains a major challenge. A technology at the convergence of additive manufacturing and electrospinning–melt electrospinning writing (MEW)–is also limited in thickness/volume due to the accumulation of excess charge from the deposited material repelling and hence, distorting scaffold architectures. The underlying physical principles are studied that constrain MEW of thick, large volume scaffolds. Through computational modeling, numerical values variable working distances are established respectively, which maintain the electrostatic force at a constant level during the printing process. Based on the computational simulations, three voltage profiles are applied to determine the maximum height (exceeding 7 mm) of a highly ordered large volume scaffold. These thick MEW scaffolds have fully interconnected pores and allow cells to migrate and proliferate. To the best of the authors knowledge, this is the first study to report that z‐axis adjustment and increasing the voltage during the MEW process allows for the fabrication of high‐volume scaffolds with uniform morphologies and fiber diameters. 相似文献
46.
A theoretical evaluation is presented of the mean time to first slip for some closed-loop synchronizer schemes to be used in a coherent serial receiver for offset binary modulations. Various modulation formats belonging to this class are considered, and the mean time to first slip is computed for each modulation type for different values of loop bandwidth and signal-to-noise ratio. Theoretical results are confirmed by extensive computer simulations 相似文献
47.
48.
Lenzini L. Luise M. Reggiannini R. 《Selected Areas in Communications, IEEE Journal on》2001,19(6):1153-1163
One key requirement for radio access in advanced, third generation (3G) mobile communication systems is the ability to accommodate a variety of services via a flexible and efficient medium access control (MAC) protocol. The paper presents and evaluates a new multiple access protocol termed CRDA (collision resolution and dynamic allocation), which has the potential to meet the above requirement. CRDA is basically a slotted packet-reservation multiple access technique with dedicated reservation slots, which allows the main shortcoming of previous PRMA schemes, i.e., contention, to be overcome through the integration in the MAC protocol of a code-division multiple-access (CDMA) transmission mode used to access the reservation slots. This prevents collisions during the reservation phase and enhances channel throughput, notably in the case of mixed voice/data traffic. Our simulations of the CRDA MAC integrate voice channels with data sources, generating what we call advanced data traffic, which has a very similar shape to the actual traffic generated by World Wide Web (WWW) applications. The standard assumption of Poissonian data traffic is also considered. Our conclusion is that the CRDA MAC protocol satisfactorily accommodates both types of traffic 相似文献
49.
Reiner Hamm Djurdjica Masic und Luise Tetzlaff 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1971,147(2):71-76
Zusammenfassung Gefrieren (-20° C) and Auftauen der Brust- and Schenkelmuskulatur verschiedener Geflügelarten (Huhn, Pute, Gans, Ente) führte zu keiner nennenswerten Änderung der gesamten Aktivität der Aspartat-Aminotransferase (Glutamat-Oxalacetat-Transaminase; GOT) im Gewebe. Längere Gefrierlagerung (3 Monate) bei -20° C brachte beim Brustmuskel des Huhns keine Änderung, beim Schenkelmuskel jedoch eine Abnahme der gesamten GOT-Aktivität mit sich. Der Muskelpreßsaft von gefrorenem and aufgetautem Gewebe enthielt bei beiden Muskeln aller untersuchten Geflügelarten eine höhere GOT-Aktivität als der Preßsaft des frischen, nicht gefrorenen Gewebes. Diese Erhöhung der GOT-Aktivität beruht auf einer durch Gefrieren and Auftauen hervorgerufenen partiellen Freisetzung des Mitochondrien-Isozyms GOTM in das Sarkoplasma. Offensichtlich werden die Membranen der Muskelmitochondrien durch Gefrieren des Gewebes geschädigt. Es wird eine auf diesen Resultaten beruhende Routinemethode zur Unterscheidung zwischen Frischgeflügel and aufgetautem Gefriergeflügel beschrieben.
Fräulein Herta Sauer danken wir fur ihre fleißige and geschickte Mitarbeit. 相似文献
Influence of freezing and thawing on the subcellular distribution of aspartate aminotransferase in poultry muscle
Summary Freezing (—20° C) and thawing of the breast and thigh muscles of poultry (chicken, turkey, goose, duck) did not result in a remarkable change of the total activity of aspartate amino transferase (glutamate-oxaloacetic transaminase; GOT) in the tissue. Freeze-storage for three months (-20° C) did not cause changes in the total GOT activity in chicken breast muscle but did lower the GOT activity in the thigh muscle of chicken. For both types of muscle of all species investigated, freezing and thawing of tissue caused an increase in the GOT activity of the muscle press-juice. This increase of GOT activity is due to a partial release of the mitochondria) isozyme GOTM into the sarcoplasma. Apparently the membranes of the muscle mitochondria are damaged by the process of freezing. A routine method basing on these results is decsribed which allows a differentiation between nonfrozen poultry and frozen and thawed poultry.
Fräulein Herta Sauer danken wir fur ihre fleißige and geschickte Mitarbeit. 相似文献
50.
Migration towards a full-digital implementation of modems is currently one of the main trends in transmission systems design. The authors describe a noncoherent all-digital delay lock loop (DDLL) suited for chip timing synchronization in band-limited direct sequence spread spectrum (DS/SS) systems, and they thoroughly analyze its performance. The key features of this novel scheme are represented by its low-complexity processing section together with its good tracking capability. Analytical expressions for the DDLL S-curve and steady-state timing jitter are derived and confirmed by a time-domain computer simulation. Furthermore, the Mean Time to Lose Lock (MTLL) of the loop is evaluated and some numerical results are reported. The proposed chip timing synchronization scheme reveals also an improved tracking performance when compared to the traditional analog DLL for rectangular chip DS/SS signals 相似文献