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991.
D Brown J Lydon M McLaughlin A Stuart-Tilley R Tyszkowski S Alper 《Canadian Metallurgical Quarterly》1996,105(4):261-267
BACKGROUND: Steroid 5 alpha-reductase is essential for the intracellular accumulation of dihydrotestosterone (DHT), which mediates androgen effects on target tissue. METHODS: In the present study, we describe the differential expression and cellular localization of 5 alpha-reductase 1 and 2 isoenzymes in the human prostate, and untreated and hormone-resistant prostatic carcinomas. The secretory epithelium of normal and hyperplastic glands showed strong nuclear 5 alpha-reductase 1 reactivity. Accordingly, the DHT forming 5 alpha-reductase process in secretory luminal cell types may be mediated predominantly by the type 1 isoenzyme. The androgen-independent basal cell layer variably expressed type 1 and 2 isoenzymes in nuclear and cytoplasmatic compartments. This suggests that circulating androgens are involved to control the basal cell layer, which represents the proliferative compartment of the human prostate. RESULTS: When compared with benign prostate tissue, increased 5 alpha-reductase reactivity was detected in prostate cancer, particularly in high-grade tumors and androgen-insensitive states of the disease. In cancerous lesions, the type 1 isoenzyme tended to shift to the cytoplasm, while the nuclear staining remained unchanged or slightly increased. Referring to the type 2 isoenzyme, increased cytoplasmatic and nuclear enzyme activity was detected in malignant cells when compared with adjacent benign prostate tissue. Even endocrine differentiated tumor cells that consistently lacked the nuclear androgen receptor variably expressed 5 alpha-reductase immunoreactivity. CONCLUSIONS: Although the functional significance of the differential subcellular localization of type 1 and 2 isoenzymes is currently unknown, the present data suggest that prostate cancer retains the DHT forming 5 alpha-reductase process in high-grade lesions and recurrent disease. Accordingly, circulating androgens may be still significant in these hormone-refractory malignancies. 相似文献
992.
Polyamidoamine dendrimers up to the fourth generation have been grown with unprecedentedly high loading within the channels of pore‐expanded (10.6 nm) MCM‐41 silica. In‐depth characterization using nitrogen adsorption, solid‐state NMR, FTIR, thermogravimetry, and elemental analysis showed that the dendrimers grow inside the channels with an average yield better than 99 %. The pore size and structure of the support have been found to be determining factors as to how much dendrimer growth can be achieved. 相似文献
993.
Z Bu?ra N Koylan A Vural F Erzengin B Umman E Yilmaz M Meri? K Büyük?ztürk 《Canadian Metallurgical Quarterly》1998,11(10):1164-1170
The spectrum of left ventricular adaptation to hypertension, different types of hypertrophy patterns, and QT dispersion in different types of hypertrophy was investigated in 107 patients with untreated essential hypertension and 30 age- and gender-matched normal adults studied by 12-derivation electrocardiogram (ECG), two-dimensional, and M-mode echocardiography. Left ventricular mass (LVM), body mass index, total peripheral resistance (TPR), relative wall thickness (RWT), and QT dispersion were found to be statistically significantly higher in the hypertension group (P < .001 for all). Among hypertensive patients, 41.1% had both normal LVM and RWT, here called normal left ventricle in hypertension; 10.3% had concentric hypertrophy with increased LVM and RWT; 14.95% had eccentric hypertrophy with increased LVM and normal RWT; and 32.7% had concentric remodeling with normal LVM and increased RWT. Echocardiographically derived cardiac index was higher in the concentric hypertrophy and eccentric hypertrophy patterns (P = .002 and P < .0001, respectively), whereas TPR was higher in the concentric hypertrophy and concentric remodeling patterns (P = .017 and .02, respectively). QT dispersion values were found to be increased in the hypertensive group (P = .001), whereas similar values were calculated for different types of hypertrophy patterns. We conclude that the more common types of ventricular adaptation to essential hypertension are eccentric hypertrophy and concentric remodeling. Concentric hypertrophy is found to be associated with both volume and pressure overload, whereas eccentric hypertrophy is associated with volume overload only and concentric remodeling is associated with pressure overload. But different left ventricular geometric patterns seem to have similar effects on QT dispersion. 相似文献
994.
Checking the correctness of software is a growing challenge. In this paper, we present a prototype implementation of Partial Order Trace Analyzer (POTA), a tool for checking execution traces of both message passing and shared memory programs using temporal logic. So far runtime verification tools have used the total order model of an execution trace, whereas POTA uses a partial order model. The partial order model enables us to capture possibly exponential number of interleavings and, in turn, this allows us to find bugs that are not found using a total order model. However, verification in partial order model suffers from the state explosion problem – the number of possible global states in a program increases exponentially with the number of processes.POTA employs an effective abstraction technique called computation slicing. A slice of a computation (execution trace) with respect to a predicate is the computation with the least number of global states that contains all global states of the original computation for which the predicate evaluates to true. The advantage of this technique is that, it mitigates the state explosion problem by reasoning only on the part of the global state space that is of interest. In POTA, we implement computing slicing algorithms for temporal logic predicates from a subset of CTL. The overall complexity of evaluating a predicate in this logic upon using computation slicing becomes polynomial in the number of processes compared to exponential without slicing.We illustrate the effectiveness of our techniques in POTA on several test cases such as the General Inter-ORB Protocol (GIOP)[18] and the primary secondary protocol[32]. POTA also contains a module that translates execution traces to Promela[16] (input language SPIN). This module enables us to compare our results on execution traces with SPIN. In some cases, we were able to verify traces with 250 processes compared to only 10 processes using SPIN. 相似文献
995.
Delfyett P.J. Gee S. Myoung-Taek Choi Izadpanah H. Wangkuen Lee Ozharar S. Quinlan F. Yilmaz T. 《Lightwave Technology, Journal of》2006,24(7):2701-2719
Modelocked semiconductor lasers are used to generate a set of phase-locked optical frequencies on a periodic grid. The periodic and phase coherent nature of the optical frequency combs makes it possible for the realization of high-performance optical and RF arbitrary-waveform synthesis. In addition, the resulting optical frequency components can be used for communication applications relying on direct detection, dense wavelength division multiplexing (WDM), coherent-detection WDM, optical time-division multiplexing, and optical code division multiple access. This paper highlights the recent results in the use of optical frequency combs generated from semiconductors for ultrawideband signal processing and communication applications. 相似文献
996.
IEEE 802.17 resilient packet ring tutorial 总被引:11,自引:0,他引:11
IEEE Working Group 802.17 is standardizing a new ring topology network architecture, called the resilient packet ring, to be used mainly in metropolitan and wide area networks. This article presents a technology background, gives an overview, and explains some of the design choices behind RPR. Some major architectural features are illustrated and compared by showing performance evaluation results using the RPR simulator developed at Simula Research Laboratory using the OPNET modeler simulation environment. 相似文献
997.
Yilmaz A.E. Jian-Ming Jin Michielssen E. 《Microwave and Wireless Components Letters, IEEE》2006,16(3):122-124
A time-domain integral-equation based hybrid electromagnetic (EM)-circuit (CKT) simulator that allows the signals (fields/voltages/currents) in each EM or CKT subsystem to be sampled and tracked using a local, subsystem-specific, time-step size is proposed. The proposed asynchronous time-stepping/coupling approach generalizes the standard synchronous time-stepping/coupling approach, where all the signals in the entire system are tracked using one system-global time-step size. The nonlinear analysis of a bipolar junction transistor driven chip-to-package interconnect demonstrates that the asynchronous simulator exhibits improved accuracy, efficiency, and convergence. 相似文献
998.
Cellular radio networks continuously evolve to respond the exponential growth in data traffic volume in mobile communications. Active antenna technology contributes to this evolution by introducing vertical sectorization, which splits the horizontal sector into two subsectors with respect to the elevation plane and doubles the number of cells that can be deployed. However, in order to guarantee a reliable and near-optimal operation of vertical sectorization in a system that applies universal frequency reuse, such as LTE-advanced, co-channel interference mitigation is essentially needed. In this article we propose a decentralized self-optimization method that can be used to mitigate the undesirable inter-cell interference by self-tuning the electrical antenna downtilt toward the optimal antenna elevation angle. The performance evaluations for the proposed self-optimization method are carried out for both coordinated and uncoordinated subsector transmission scenarios within the LTE-advanced framework using a dynamic LTE-advanced compliant system level SON simulator. Based on the extensive performance evaluations carried out for a realistic urban scenario, it is found that self-optimization improves the vertical sectorization performance 25 % in terms of virtual load. Furthermore, the performance gain reaches up to 30 % when vertical vectorization is provided with dynamic point selection and muting feature. Therefore, the article concludes that in LTE-advanced networks vertical sectorization can largely benefit from the antenna self-optimization and outperform the traditional horizontal sectorization approach with low algorithmic complexity. 相似文献
999.
Solvent‐free synthesis of chiral molecularly imprinted polymers: Porosity control using a nano‐sized solid porogen
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Molecularly imprinted polymers (MIPs) have been synthesized in the absence of a solvent using fumed silica nanoparticles to create a porous network. The method employed led to a chiral imprinting effect and allowed for an excellent control over the internal morphology of imprinted and non‐imprinted polymer (NIP) materials. The polymers possess high surface areas (>300 m2) and identical pore size (112 Å). The MIP exhibited an imprinting factor (IF) of 9 and a selectivity value (α) of 1.83 for (?)‐ephedrine. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44104. 相似文献
1000.