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排序方式: 共有345条查询结果,搜索用时 0 毫秒
71.
A new method of impulse radio ultra-wideband (IR-UWB) pulse generation, with advantage of providing a “notch” like representation of pulse in the spectrum domain for particular control parameters values, is investigated in this paper. Low power pulse generator is composed of a glitch generator, a switched oscillator, a two-stage buffer and a pulse shaping filter. The proposed architecture, designed in UMC 0.18 µm CMOS technology, can operate in a single band from 3.3 GHz to 9.3 GHz or in a double, lower and higher UWB band (from 3 GHz to 9.15 GHz), suppressing frequencies in the WLAN band. Both spectrums fully comply with the corresponding FCC spectral mask, while the pulse generator regime and the spectrum range are determined by control signal values. Post-layout simulation results showed a pulse width of 0.5 ns, and a peak-to-peak amplitude of 211 mV for one band spectrum. The average power consumption is 0.89 mW corresponding to the energy consumption of 8.9 pJ/pulse for 100 MHz pulse repetition rate (PRF). The pulse duration is 1 ns and peak-to-peak amplitude is 202 mV in the case of the WLAN frequency band suppression. The total chip area is 0.31 mm2. The pulse generator has been evaluated for the best performance supporting the on-off keying (OOK) modulation. 相似文献
72.
Hoskovcová Simona; Hoskovec Ji?í; Plháková Alena; ?ebek Michael; ?vancara Josef; Vobo?il Dalibor 《Canadian Metallurgical Quarterly》2010,13(3):309
The paper is aimed at presenting the development of the Czech historiography of psychology, which was strongly influenced by the political changes in Central and Eastern Europe. The authors deal with the historiography of psychology at the three universities offering an undergraduate program in psychology, located in Prague, Brno, and Olomouc, and at the Institute of Psychology of the Czech Academy of Sciences. Recent research, teaching, textbooks, and journal articles published in Czech and in foreign languages are showcased. The historiography of Czech psychotherapy is mentioned as a special thematic development. Contemporary problems and perspectives in the field of the history of psychology in the Czech Republic are discussed, sources of information are given. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
73.
Bladder Runner: Visual Analytics for the Exploration of RT‐Induced Bladder Toxicity in a Cohort Study 下载免费PDF全文
R.G. Raidou O. Casares‐Magaz A. Amirkhanov V. Moiseenko L.P. Muren J.P. Einck A. Vilanova M.E. Gröller 《Computer Graphics Forum》2018,37(3):205-216
We present the Bladder Runner, a novel tool to enable detailed visual exploration and analysis of the impact of bladder shape variation on the accuracy of dose delivery, during the course of prostate cancer radiotherapy (RT). Our tool enables the investigation of individual patients and cohorts through the entire treatment process, and it can give indications of RT‐induced complications for the patient. In prostate cancer RT treatment, despite the design of an initial plan prior to dose administration, bladder toxicity remains very common. The main reason is that the dose is delivered in multiple fractions over a period of weeks, during which, the anatomical variation of the bladder – due to differences in urinary filling – causes deviations between planned and delivered doses. Clinical researchers want to correlate bladder shape variations to dose deviations and toxicity risk through cohort studies, to understand which specific bladder shape characteristics are more prone to side effects. This is currently done with Dose‐Volume Histograms (DVHs), which provide limited, qualitative insight. The effect of bladder variation on dose delivery and the resulting toxicity cannot be currently examined with the DVHs. To address this need, we designed and implemented the Bladder Runner, which incorporates visualization strategies in a highly interactive environment with multiple linked views. Individual patients can be explored and analyzed through the entire treatment period, while inter‐patient and temporal exploration, analysis and comparison are also supported. We demonstrate the applicability of our presented tool with a usage scenario, employing a dataset of 29 patients followed through the course of the treatment, across 13 time points. We conducted an evaluation with three clinical researchers working on the investigation of RT‐induced bladder toxicity. All participants agreed that Bladder Runner provides better understanding and new opportunities for the exploration and analysis of the involved cohort data. 相似文献
74.
Number and size of lupulin glands,glandular trichomes of hop (Humulus lupulus L.), play a key role in contents of bitter acids and polyphenols in hop cone 下载免费PDF全文
Josef Patzak Karel Krofta Alena Henychová Vladimír Nesvadba 《International Journal of Food Science & Technology》2015,50(8):1864-1872
Hop (Humulus lupulus L.) inflorescence, commonly known as ‘hop cone’, is valuable for contents of bitter acids, essential oils and polyphenols, used in brewing industry and biomedical application. These compounds are predominantly formed in glandular trichomes, known as ‘lupulin glands’. In this study, we investigated chemical and morphological characteristics of lupulin glands by microscopy and HPLC analyses. Even though no significant correlations were found between lupulin glands and hop cones for contents of alpha and beta bitter acids, polyphenols, all ratios between individual metabolites (alpha/beta acids, X/alpha acids, X/DMX) were highly and significantly correlated. The average number of lupulin glands on bract/bracteole ranged from 115 to 713 with 28.5% of variability. Linear regression analyses confirmed that total volume of lupulin glands and total lupulin glands area on bract/bracteole surface highly correlated with contents of bitter acids and polyphenols in hop cone. Therefore, lupulin glands are unique and exclusive organs responsible for contents of bitter acids and polyphenols in hop cone. 相似文献
75.
The safety effects of section control were investigated at 14 sites in Norway. A before–after study was conducted with the empirical Bayes method in order to control for regression to the mean (RTM). Effects of trend, volumes, speed limit changes and speed cameras at some of the sites in the before period are controlled for as well. For injury crashes a non-significant reduction by 12% was found. The number of killed or severely injured was found to be significantly reduced by 49% at the section control sites. The results indicate that the crash reductions in tunnels (most of which are undersea tunnels with section control on steep downhill segments) are at least of the same magnitude as on open roads. The results are consistent with findings from speed measurements, although the crash reductions are larger than one would expect as a result from the speed reductions. Downstream of the section control sites (up to 3 km in each direction) injury crashes were found to be significantly reduced by 46%. The number of KSI downstream of the section control sites is too small for drawing any conclusions. It is concluded that section control is effective in reducing both speed and crashes, especially serious crashes, and that spillover effects (crash reductions at non-enforcement sites) are more likely to occur than crash migration. The size of the effects that were found should be interpreted with caution because of the relatively short after periods for some of the sites and the sensitivity of the results to the outcomes of individual crashes. 相似文献
76.
Alena Buyx M.A. 《Ethik in der Medizin》2010,22(3):221-234
Definition of the problem Due to the epidemiological transition that has occurred over the last few decades, diseases caused by behaviour have become one of the most important challenges for modern public health practice and policy. However, assigning responsibility for health and modifying behaviour are fraught with ethical problems. As of now, there is still the need for a theoretical model which manages to solve these issues successfully. Arguments Recently, libertarian paternalism has been heralded as a theoretical model which can inform policy making in public health and other areas of social policy. This article describes the account and discusses some of its problematic features. Conclusions To satisfy requirements of a fully argued normative account, libertarian paternalism lacks central elements of justification. However, it serves very well as a pragmatic tool providing original ideas for designing acceptable public health policy. 相似文献
77.
78.
Thierbach S Büldt-Karentzopoulos K Dreiling A Hennecke U König S Fetzner S 《Chembiochem : a European journal of chemical biology》2012,13(8):1125-1127
Mechanistic promiscuity: The (2-alkyl)-3-hydroxy-4(1H)-quinolone-cleaving dioxygenase Hod has an α/β-hydrolase fold and a Ser/His/Asp triad in its active site. Isatoic anhydride, a suicide substrate of serine hydrolases, inactivates Hod by covalent modification of the active-site serine, thus indicating that the α/β-hydrolase fold can accommodate dioxygenase chemistry without completely abandoning hydrolase-like properties. 相似文献
79.
The results are given of the test development of different structural options of full-scale pastecooled modules of the insulating
wall of the channel of a pulsed MHD generator of the Pamir type [1,2] under conditions of repeated heat loading in the jet
of a plasma generator. Two cooling agents are employed for this development, which are characterized by different fillers,
namely, ammonium oxalate and carbamide. A module in the form of a perforated cup exhibits the best results. 相似文献
80.
Kateřina Krejčová Miloslava Rabišková David Vetchý Ermin Polášek Václav Tomášek Alena Prokopová 《Drug development and industrial pharmacy》2013,39(5):585-593
ABSTRACTPellets containing drugs of different properties were prepared in a Rotoprocessor in order to study changes in the formulation process and resulting pellet characteristics. Diltiazem hydrochloride, diclofenac sodium, and theophylline were chosen as model drugs. Pellet size distribution, sphericity, density, hardness, friability, and repose angle were determined using standard methods. The amount of water as a wetting agent necessary for successful pellet formulation was observed for each sample and changed depending on drug solubility, concentration, and particle size. The pelletization of freely soluble diltiazem hydrochloride required 24.8–23.1% of the wetting agent and its amount decreased as the drug concentration increased. The demand for water in the formulation of theophylline pellets was 31.0–34.4% and it increased with increasing drug concentration. The pellet samples containing both drugs were easy to prepare. However, the cohesion of micronized diclofenac sodium particles negatively influenced both the pellet size distribution and the formulation process itself. When the drug concentration exceeded 40%, it was not possible to produce pellets of an appropriate size and the process was not reproducible. 相似文献