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1.
Wireless Networks - Orthogonal frequency-division multiplexing with random multiple access (OFDRMA) is discussed for down-link communications, whereby a single base-station transmits information... 相似文献
2.
Riley William T.; Schumann Mary F.; Forman-Hoffman Valerie L.; Mihm Patricia; Applegate Bradford W.; Asif Ofer 《Canadian Metallurgical Quarterly》2007,38(1):44
Increased adoption of empirically supported treatments (ESTs) has been hindered in part by inadequate and inconvenient access to EST information and training. To improve diffusion of ESTs, the authors developed a Web application to provide practitioners with concise information by disorder on ESTs. The resulting site, therapyadvisor.com, was evaluated by 239 practicing psychologists to assess the usefulness of the site and explore possible interactions of EST attitudes on ratings of usefulness and impact. Two thirds of participants indicated using ESTs in practice, and limited time and resources were cited as primary barriers to EST adoption. The Web application was rated positively by most participants and was reported to increase awareness of and commitment to try ESTs among approximately 60% of participants. The results of this project support the feasibility of a Web application to increase diffusion and promote further adoption of ESTs. Technological and e-learning advances are promising directions for encouraging the adoption of ESTs specifically and evidence-based practice generally, particularly among busy practitioners who have inadequate time and resources for more traditional forms of dissemination and training. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
3.
Previous research has shown that under certain conditions environmental cues associated with morphine administration induce drug-opposite conditioned effects that mimic symptoms of opiate withdrawal. R. V. McDonald and S. Siegel (see record 2004-10475-001) extend these observations by demonstrating that acute exposure to a low dose of morphine induces symptoms of opiate withdrawal in rats previously exposed to a high dose of morphine. They hypothesized that early drug onset cues, repeatedly paired with later, larger drug effects, mediate the paradoxical effect of the low drug dose on behavior. They also hypothesized that conditioned withdrawal symptoms induced by the early drug onset cues may mediate the "priming" effect of drugs on relapse and craving. The authors of this comment discuss the degree to which the literature supports this hypothesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
4.
Mössbauer studies of Fe2+ in water-soaked nafion polymer membranes in the temperature range between 90 K and 250 K have been performed. Above a critical temperature (~ 180 K) the spectra exhibit both elastic narrow absorption lines and quasielastic broad lines. These spectra are typical of bounded diffusion phenomena observed by Mössbauer spectroscopy in macromolecular systems like haemoglobin, myoglobin and ferritin. Similar spectral shapes have been observed by quasielastic neutron scattering from water in nafion membranes. Within 50 K above the critical temperature the total Mössbauer absorption area decreases by an order of magnitude whereas the narrow absorption line decreases by two orders of magnitude. The results are interpreted in terms of bounded diffusive motion of the iron. Using a model based on overdamped harmonically bound Brownian motion, the essential parameters of the iron motion can be derived as a function of temperature. The iron motion most probably reflects the motion of a large Fe2+ complex, e.g. Fe(H2O)2+6, which is attached to the polymer side chains via the sulphonic group. 相似文献
5.
6.
Anatomic snapshot memory object in shared memory systems enables a set of processes, calledscanners, to obtain a consistent picture of the shared memory while other processes, calledupdaters, keep updating memory locations concurrently. In this paper we present two conversion methods of snapshot implementations. Using the first conversion method we obtain a new snapshot implementation in which the scan operation has linear time complexity and the time complexity of the update operation becomes the sum of the time complexities of the original implementation. Applying the second conversion method yields similar results, where in this case the time complexity of the update protocol becomes linear. Although our conversion methods use unbounded space, their space complexity can be bounded using known techniques. One of the most intriguing open problems in distributed wait-free computing is the existence of a linear-time implementation of this object. Using our conversion methods and known constructions we obtain the following results: ?Consider a system ofn processes, each an updater and a scanner. We present an implementation in which the time complexity of either the update or the scan operation is linear, while the time complexity of the second operation isO(n logn). ?We present an implementation with linear time complexity when the number of either updaters or scanners isO(n/logn), wheren is the total number of processes. ?We present an implementation with amortized linear time complexity when one of the protocols (either upate or scan) is executed significantly more often than the other protocol. 相似文献
7.
The paper focuses on mining clusters that are characterized by a lagged relationship between the data objects. We call such
clusters lagged co-clusters. A lagged co-cluster of a matrix is a submatrix determined by a subset of rows and their corresponding lag over a subset
of columns. Extracting such subsets may reveal an underlying governing regulatory mechanism. Such a regulatory mechanism is
quite common in real-life settings. It appears in a variety of fields: meteorology, seismic activity, stock market behavior,
neuronal brain activity, river flow, and navigation, but a limited list of examples. Mining such lagged co-clusters not only
helps in understanding the relationship between objects in the domain, but assists in forecasting their future behavior. For
most interesting variants of this problem, finding an optimal lagged co-cluster is NP-complete problem. We present a polynomial-time
Monte-Carlo algorithm for mining lagged co-clusters. We prove that, with fixed probability, the algorithm mines a lagged co-cluster
which encompasses the optimal lagged co-cluster by a maximum 2 ratio columns overhead and completely no rows overhead. Moreover,
the algorithm handles noise, anti-correlations, missing values, and overlapping patterns. The algorithm is extensively evaluated
using both artificial and real-world test environments. The first enable the evaluation of specific, isolated properties of
the algorithm. The latter (river flow and topographic data) enable the evaluation of the algorithm to efficiently mine relevant
and coherent lagged co-clusters in environments that are temporal, i.e., time reading data and non-temporal. 相似文献
8.
Deformation Control During Thermal Treatment of Electrospun PbZr0.52Ti0.48O3 Nanofiber Mats
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Ofer Rozent Vadim V. Beilin Gennady E. Shter Gideon S. Grader 《Journal of the American Ceramic Society》2016,99(5):1550-1556
This paper focuses on the deformation origin of PbZr0.52Ti0.48O3 (PZT) fiber mats obtained by electrospinning. The main cause of deformation of the green mats during heating was found to be a nonuniform relaxation of the stretched PVP polymer, due to nonuniform thermal decomposition of the Pb‐hexanoate in the fibers. This relaxation starts under 100°C, well below the polymer decomposition temperature. The shrinkage was found to accelerate above the polymer glass transition point, giving rise to an overall linear change of almost 50%. The “green” PZT mats were easily separated from the collector by first depositing a pure PVP sublayer on the collector. An optimal fabrication and slow multistep thermal treatment process that provides fiber mats with desired PZT phase and overcomes the nonuniform deformation is described. 相似文献
9.
We propose a novel framework for regularization of symmetric positive-definite (SPD) tensors (e.g., diffusion tensors). This
framework is based on a local differential geometric approach. The manifold of symmetric positive-definite (SPD) matrices,
P
n
, is parameterized via the Iwasawa coordinate system. In this framework distances on P
n
are measured in terms of a natural GL(n)-invariant metric. Via the mathematical concept of fiber bundles, we describe the tensor-valued image as a section where
the metric over the section is induced by the metric over P
n
. Then, a functional over the sections accompanied by a suitable data fitting term is defined. The variation of this functional
with respect to the Iwasawa coordinates leads to a set of
\frac12n(n+1)\frac{1}{2}n(n+1)
coupled equations of motion. By means of the gradient descent method, these equations of motion define a Beltrami flow over
P
n
. It turns out that the local coordinate approach via the Iwasawa coordinate system results in very simple numerics that leads
to fast convergence of the algorithm. Regularization results as well as results of fibers tractography for DTI are presented. 相似文献
10.
Eyal Felstaine Reuven Cohen Ofer Hadar 《Journal of Network and Systems Management》2002,10(3):327-355
When an ATM node discovers that it cannot continue the setup of a virtual channel under the requested Quality of Service (QoS), it initiates a backtracking procedure called crankback. We propose a novel scheme, referred to as crankback prediction, that decreases the crankback overhead. Under the proposed scheme, nodes check during the connection admission control procedure whether the establishment of a virtual channel has a good chance to be admitted over the entire designated route. If this is not the case, crankback is initiated even before a particular QoS parameter is violated. The main idea behind the proposed scheme is to allocate a quota to the Peer Groups (PGs) along the message path, and then to suballocate this quota to the child PGs of these PGs. This process continues recursively until reaching the 1-level PG, which contains only physical nodes. The main advantage of the proposed scheme is that it lowers the setup delay and the processing and communication load imposed by signaling messages that establish unused portions of Virtual Channels (VCs) 相似文献