11,403 research outputs found
Freeze-out in hydrodynamical models in relativistic heavy ion collisions
Freeze-out of particles across 3-dimensional space-time hypersurface with
space-like normal is discussed in a simple kinetic model. The final momentum
distribution of emitted particles shows a non-exponential transverse momentum
spectrum, which is in quantitative agreement with recently measured SPS pion
and spectra.Comment: 4 pages, 1 figure. Quark Matter'99 Proceeding
Enumeration of distinct mechanically stable disk packings in small systems
We create mechanically stable (MS) packings of bidisperse disks using an
algorithm in which we successively grow or shrink soft repulsive disks followed
by energy minimization until the overlaps are vanishingly small. We focus on
small systems because this enables us to enumerate nearly all distinct MS
packings. We measure the probability to obtain a MS packing at packing fraction
and find several notable results. First, the probability is highly
nonuniform. When averaged over narrow packing fraction intervals, the most
probable MS packing occurs at the highest and the probability decays
exponentially with decreasing . Even more striking, within each
packing-fraction interval, the probability can vary by many orders of
magnitude. By using two different packing-generation protocols, we show that
these results are robust and the packing frequencies do not change
qualitatively with different protocols.Comment: 4 pages, 3 figures, Conference Proceedings for X International
Workshop on Disordered System
Cost-effective approaches for high-resolution bioimaging by time-stretched confocal microscopy at 1um
Session: Optics Imaging Algorithms and Analysis IIOptical imaging based on time-stretch process has recently been proven as a powerful tool for delivering ultra-high frame rate (< 1MHz) which is not achievable by the conventional image sensors. Together with the capability of optical image amplification for overcoming the trade-off between detection sensitivity and speed, this new imaging modality is particularly valuable in high-throughput biomedical diagnostic practice, e.g. imaging flow cytometry. The ultra-high frame rate in time-stretch imaging is attained by two key enabling elements: dispersive fiber providing the time-stretch process via group-velocity-dispersion (GVD), and electronic digitizer. It is well-known that many biophotonic applications favor the spectral window of 1μm. However, reasonably high GVD (< 0.1 ns/nm) in this range can only be achieved by using specialty single-mode fiber (SMF) at 1μm. Moreover, the ultrafast detection has to rely on the state-of- the-art digitizer with significantly wide-bandwidth and high sampling rate (e.g. <10 GHz, <40 GS/s). These stringent requirements imply the prohibitively high-cost of the system and hinder its practical use in biomedical diagnostics. We here demonstrate two cost-effective approaches for realizing time-stretch confocal microscopy at 1μm: (i) using the standard telecommunication SMF (e.g. SMF28) to act as a few-mode fiber (FMF) at 1μm for the time-stretch process, and (ii) implementing the pixel super-resolution (SR) algorithm to restore the high-resolution (HR) image when using a lower-bandwidth digitizer. By using a FMF (with a GVD of 0.15ns/nm) and a modified pixel-SR algorithm, we can achieve time-stretch confocal microscopy at 1μm with cellular resolution ( 3μm) at a frame rate 1 MHz.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.published_or_final_versio
Dirac Equation with Spin Symmetry for the Modified P\"oschl-Teller Potential in -dimensions
We present solutions of the Dirac equation with spin symmetry for vector and
scalar modified P\"oschl-Teller potential within framework of an approximation
of the centrifugal term. The relativistic energy spectrum is obtained using the
Nikiforov-Uvarov method and the two-component spinor wavefunctions are obtain
are in terms of the Jacobi polynomials. It is found that there exist only
positive-energy states for bound states under spin symmetry, and the energy
levels increase with the dimension and the potential range parameter .Comment: 9 pages and 1tabl
SMART: Unique splitting-while-merging framework for gene clustering
Copyright @ 2014 Fa et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium, provided the original author and source are credited.Successful clustering algorithms are highly dependent on parameter settings. The clustering performance degrades significantly unless parameters are properly set, and yet, it is difficult to set these parameters a priori. To address this issue, in this paper, we propose a unique splitting-while-merging clustering framework, named “splitting merging awareness tactics” (SMART), which does not require any a priori knowledge of either the number of clusters or even the possible range of this number. Unlike existing self-splitting algorithms, which over-cluster the dataset to a large number of clusters and then merge some similar clusters, our framework has the ability to split and merge clusters automatically during the process and produces the the most reliable clustering results, by intrinsically integrating many clustering techniques and tasks. The SMART framework is implemented with two distinct clustering paradigms in two algorithms: competitive learning and finite mixture model. Nevertheless, within the proposed SMART framework, many other algorithms can be derived for different clustering paradigms. The minimum message length algorithm is integrated into the framework as the clustering selection criterion. The usefulness of the SMART framework and its algorithms is tested in demonstration datasets and simulated gene expression datasets. Moreover, two real microarray gene expression datasets are studied using this approach. Based on the performance of many metrics, all numerical results show that SMART is superior to compared existing self-splitting algorithms and traditional algorithms. Three main properties of the proposed SMART framework are summarized as: (1) needing no parameters dependent on the respective dataset or a priori knowledge about the datasets, (2) extendible to many different applications, (3) offering superior performance compared with counterpart algorithms.National Institute for Health Researc
Assessing framing of uncertainties in water management practice
Dealing with uncertainties in water management is an important issue and is one which will only increase in light of global changes, particularly climate change. So far, uncertainties in water management have mostly been assessed from a scientific point of view, and in quantitative terms. In this paper, we focus on the perspectives from water management practice, adopting a qualitative approach. We consider it important to know how uncertainties are framed in water management practice in order to develop practice relevant strategies for dealing with uncertainties. Framing refers to how people make sense of the world. With the aim of identifying what are important parameters for the framing of uncertainties in water management practice, in this paper we analyze uncertainty situations described by decision-makers in water management. The analysis builds on a series of ¿Uncertainty Dialogues¿ carried out within the NeWater project with water managers in the Rhine, Elbe and Guadiana basins in 2006. During these dialogues, representatives of these river basins were asked what uncertainties they encountered in their professional work life and how they confronted them. Analysing these dialogues we identified several important parameters of how uncertainties get framed. Our assumption is that making framing of uncertainty explicit for water managers will allow for better dealing with the respective uncertainty situations. Keywords Framing - Uncertainty - Water management practic
Selective targeting of activating and inhibitory Smads by distinct WWP2 ubiquitin ligase isoforms differentially modulates TGFβ signalling and EMT
Ubiquitin-dependent mechanisms have emerged as essential regulatory elements controlling cellular levels of Smads and TGFß-dependent biological outputs such as epithelial–mesenchymal transition (EMT). In this study, we identify a HECT E3 ubiquitin ligase known as WWP2 (Full-length WWP2-FL), together with two WWP2 isoforms (N-terminal, WWP2-N; C-terminal WWP2-C), as novel Smad-binding partners. We show that WWP2-FL interacts exclusively with Smad2, Smad3 and Smad7 in the TGFß pathway. Interestingly, the WWP2-N isoform interacts with Smad2 and Smad3, whereas WWP2-C interacts only with Smad7. In addition, WWP2-FL and WWP2-C have a preference for Smad7 based on protein turnover and ubiquitination studies. Unexpectedly, we also find that WWP2-N, which lacks the HECT ubiquitin ligase domain, can also interact with WWP2-FL in a TGFß-regulated manner and activate endogenous WWP2 ubiquitin ligase activity causing degradation of unstimulated Smad2 and Smad3. Consistent with our protein interaction data, overexpression and knockdown approaches reveal that WWP2 isoforms differentially modulate TGFß-dependent transcription and EMT. Finally, we show that selective disruption of WWP2 interactions with inhibitory Smad7 can stabilise Smad7 protein levels and prevent TGFß-induced EMT. Collectively, our data suggest that WWP2-N can stimulate WWP2-FL leading to increased activity against unstimulated Smad2 and Smad3, and that Smad7 is a preferred substrate for WWP2-FL and WWP2-C following prolonged TGFß stimulation. Significantly, this is the first report of an interdependent biological role for distinct HECT E3 ubiquitin ligase isoforms, and highlights an entirely novel regulatory paradigm that selectively limits the level of inhibitory and activating Smads
Three-dimensionally Ordered Macroporous Structure Enabled Nanothermite Membrane of Mn2O3/Al
Mn2O3 has been selected to realize nanothermite membrane for the first time in the literature. Mn2O3/Al nanothermite has been synthesized by magnetron sputtering a layer of Al film onto three-dimensionally ordered macroporous (3DOM) Mn2O3 skeleton. The energy release is significantly enhanced owing to the unusual 3DOM structure, which ensures Al and Mn2O3 to integrate compactly in nanoscale and greatly increase effective contact area. The morphology and DSC curve of the nanothermite membrane have been investigated at various aluminizing times. At the optimized aluminizing time of 30 min, energy release reaches a maximum of 2.09 kJ∙g−1, where the Al layer thickness plays a decisive role in the total energy release. This method possesses advantages of high compatibility with MEMS and can be applied to other nanothermite systems easily, which will make great contribution to little-known nanothermite research
Ultrafast Laser-Scanning Time-Stretch Imaging at Visible Wavelengths
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