bluuebunny/crossref_metadata_2025_split huggingface dataset:
SEP calculations for coherentM‐ary FSK in different fading channels with MRC diversity
Authors: Chandra Aniruddha , Poram Srinivasa Rao , Bose Chayanika 
Published: May 2010

AbstractIn this paper, the authors derive symbol error probability (SEP) expressions for coherentM‐ary frequency shift keying (MFSK) modulation schemes in multipath fading channels. The multipath or small‐scale fading process is assumed to be slow and frequency non‐selective. In addition, the channel is also subjected to the usual degradation caused by the additive white Gaussian noise (AWGN). Different small‐scale fading statistics such as Rayleigh, Rician (Nakagami‐n), Hoyt (Nakagami‐q), and Nakagami‐mhave been considered to portray diverse wireless environments. Further, to mitigate fading effects through space diversity, the receiver front‐end is assumed to be equipped with multiple antennas. Independent and identically distributed (IID) as well as uncorrelated signal replicas received through all these antennas are combined with a linear combiner before successive demodulation. As the detection is coherent in nature and thus involves phase estimation, optimum phase‐coherent combining algorithms, such as predetection maximal ratio combining (MRC), may be used without any added complexity to the receiver. In the current text, utilizing the alternate expressions for integer powers (1≤n≤4) of GaussianQfunction, SEP values of coherent MFSK are obtained through moment generating function (MGF) approach for all the fading models (with or without MRC diversity) described above. The derived end expressions are composed of finite range integrals, which can be numerically computed with ease, dispenses with the need of individual expressions for differentM, and gives exact values up toM=5. When the constellation size becomes bigger (M≥6), the same SEP expressions provide a quite realistic approximation, much tighter than the bounds found in previous literatures. Error probabilities are graphically displayed for each fading model with different values of constellation sizeM, diversity orderL, and for corresponding fading parameters (K,q, orm). To validate the proposed approximation method extensive Monte‐Carlo simulations were also performed, which show a close match with the analytical results deduced in the paper. Both these theoretical and simulation results offer valuable insight to assess the efficacy of relatively less studied coherent MFSK in the context of the optimum modulation choice in wireless communication. Copyright © 2010 John Wiley & Sons, Ltd.
Fluid–structure interaction modeling and performance analysis of the Orion spacecraft parachutes
Authors: Takizawa Kenji , Moorman Creighton , Wright Samuel , Spielman Timothy , Tezduyar Tayfun E. 
Published: May 2010

AbstractWe focus on fluid–structure interaction (FSI) modeling and performance analysis of the ringsail parachutes to be used with the Orion spacecraft. We address the computational challenges with the latest techniques developed by the T★AFSM (Team for Advanced Flow Simulation and Modeling) in conjunction with the SSTFSI (Stabilized Space–Time Fluid–Structure Interaction) technique. The challenges involved in FSI modeling include the geometric porosity of the ringsail parachutes with ring gaps and sail slits. We investigate the performance of three possible design configurations of the parachute canopy. We also describe the techniques developed recently for building a consistent starting condition for the FSI computations, discuss rotational periodicity techniques for improving the geometric‐porosity modeling, and introduce a new version of the HMGP (Homogenized Modeling of Geometric Porosity). Copyright © 2010 John Wiley & Sons, Ltd.
Unsteady CFD computations using vertex‐centered finite volumes for unstructured grids on Graphics Processing Units
Authors: Asouti V. G. , Trompoukis X. S. , Kampolis I. C. , Giannakoglou K. C. 
Published: May 2010

AbstractThis paper presents a Navier–Stokes solver for steady and unsteady turbulent flows on unstructured/hybrid grids, with triangular and quadrilateral elements, which was implemented to run on Graphics Processing Units (GPUs). The paper focuses on programming issues for efficiently porting the CPU code to the GPU, using the CUDA language. Compared with cell‐centered schemes, the use of a vertex‐centered finite volume scheme on unstructured grids increases the programming complexity since the number of nodes connected by edge to any other node might vary a lot. Thus, delicate GPU memory handling is absolutely necessary in order to maximize the speed‐up of the GPU implementation with respect to the Fortran code running on a single CPU core. The developed GPU‐enabled code is used to numerically study steady and unsteady flows around the supercritical airfoil OAT15A, by laying emphasis on the transonic buffet phenomenon. The computations were carried out on NVIDIA's Ge‐Force GTX 285 graphics cards and speed‐ups up to ∼46 × (on a single GPU, with double precision arithmetic) are reported. Copyright © 2010 John Wiley & Sons, Ltd.
The estimation of functional uncertainty using polynomial chaos and adjoint equations
Authors: Alekseev A. K. , Navon I. M. , Zelentsov M. E. 
Published: May 2010

AbstractThe combined use of nonintrusive polynomial chaos (PC) and adjoint equations (yielding the gradient) is addressed aimed at the estimation of uncertainty of a valuable functional subject to large errors in the input data. Random variables providing maximum impact on the result (leading values) may be found using the gradient information that allows reduction of the problem dimension. The gradient may be also used for the calculation of PC coefficients, thus enabling further acceleration of the computations. Copyright © 2010 John Wiley & Sons, Ltd.
Tight and efficient enclosure of matrix multiplication by using optimized BLAS
Authors: Ozaki Katsuhisa , Ogita Takeshi , Oishi Shin'ichi 
Published: May 2010

AbstractThis paper is concerned with the tight enclosure of matrix multiplication AB for two floating‐point matrices A and B. The aim of this paper is to compute component‐wise upper and lower bounds of the exact result C of the matrix multiplication AB by floating‐point arithmetic. Namely, an interval matrix enclosing C is obtained. In this paper, new algorithms for enclosing C are proposed. The proposed algorithms are designed to mainly exploit the level 3 operations in BLAS. Although the proposed algorithms take around twice as much costs as a standard algorithm promoted by Oishi and Rump, the accuracy of the result by the proposed algorithms is better than that of the standard algorithm. At the end of this paper, we present numerical examples showing the efficiency of the proposed algorithms. Copyright © 2010 John Wiley & Sons, Ltd.
Surface analytical characterization of micro‐fluidic devices hot embossed in polymer wafers: Surface chemistry and wettability
Authors: Baytekin H. T. , Wirth Thomas , Gross Thomas , Sahre Mario , Unger Wolfgang E. S. , Theisen Janko , Schmidt Martin 
Published: May 2010

AbstractRecently, time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) and X‐ray photoelectron spectroscopy (XPS) instrumentation has been used to address areas of interest within micro‐fluidic devices providing full access to the surface chemistry established at the bottom of micro‐channels therein. After careful calibration, information on surface chemistry as obtained by ToF‐SIMS or XPS can be interpreted in terms of wettability expressed as contact angles which are then characteristic for the inner walls of micro‐channels. Standard contact angle measurement is not applicable in micro‐channels. The approach has been demonstrated to be successful with two different micro‐fluidic devices hot embossed into high‐end quality poly(methyl methacrylate) (PMMA) or Polycarbonate wafers. A pre‐selected surface chemistry at micro‐channel walls can be established by plasma technologies but ageing and rinsing effects have to be under control. A combination of ToF‐SIMS, XPS and contact angle measurement techniques has been demonstrated to provide the required information. Finally, it is shown by ToF‐SIMS and XPS analysis that in the production of micro‐fluidic parts during practical processing using hot embossing technologies, material originating from cover foils will reside on the polymer wafer's surface. Moreover, residues of releasing agents as silicone oil used during processing can be detected by ToF‐SIMS. Both cover foil residues and silicones are issues of trouble shooting in micro‐fluidics because they will change contact angles efficiently. Copyright © 2010 John Wiley & Sons, Ltd.
Effect of SiC coating on interfacial reaction between carbon short fiber and Al melt
Authors: Kim Il‐Ho , Lee Wonsik , Lee C.‐W. , Ko Se‐Hyun , Jang Jin‐Man 
Published: May 2010

AbstractThis study aims to investigate the effects of SiC coating on the degradation of carbon short fiber in Al melt. The SiC coating on the surface of carbon short fiber is performed at 1500 °C in Ar atmosphere by carbothermal reduction method after precoating with silica sol on the surface of carbon short fibers. The SiC coating layer is successfully formed with a mean thickness of 160 nm. The pure carbon short fibers without SiC coating was degraded rapidly in Al melt. After maintenance for 180 min in Al melt of 800 °C, carbon fibers did not remain. On the other hand, the carbon short fibers with SiC coating layer maintained the shape of initial carbon fiber up to 180 min in Al melt. However, with increase of reaction time in Al melt, SiC coating layer gradually dissolved and after 180 min, the coating layer was not observed in some areas on the surface of fiber. Also, concentration of Al in carbon fiber increased with the maintenance time in Al melt. As a consequence, SiC coating layer can retard effectively degradation of the carbon short fibers, even though it is only a few hundred nanometers thick. Copyright © 2010 John Wiley & Sons, Ltd.
Investigating the fundamentals of molecular depth profiling using strong‐field photoionization of sputtered neutrals
Authors: Willingham D. , Brenes D. A. , Winograd N. , Wucher A. 
Published: May 2010

AbstractMolecular depth profiling of model organic thin films were performed using a 40 keV C60+ cluster ion source in concert with TOF‐SIMS. Strong‐field photoionization of intact neutral molecules sputtered by 40 keV C60+ primary ions was used to analyze changes in the chemical environment of the guanine thin films as a function of ion fluence. Direct comparison of the secondary ion and neutral components of the molecular depth profiles yields valuable information about chemical damage accumulation as well as changes in the molecular ionization probability. An analytical protocol based on the erosion dynamics model is developed and evaluated using guanine and trehalose molecular secondary ion signals with and without comparable laser photoionization data. Copyright © 2010 John Wiley & Sons, Ltd.
The influence of beam energy on apparent layer thickness using ultralow energy O2+ SIMS on surface Si1−xGex
Authors: Dowsett M. G. , Morris R. J. H. , Hand M. , Grigg A. T. , Walker D. , Beanland R. 
Published: May 2010

AbstractA technique that employs energy sequencing, i.e. depth profiling a sample for a range of beam energies and then extrapolating the profile shape to zero beam energy, has been proposed as a means for removing the effects of atomic mixing and surface transient behavior. Here we have tested this approach in an attempt to establish the accurate thickness of a superficial (∼30 nm) Si1−xGex (x ∼ 0.3) layer. The conditions used were near‐normal incidence O2+ and the energy range 0.25–2.5 keV. Energy‐dependent apparent layer thicknesses were extracted for numerous points (90, 85, 75, 50, 21 and 10%) across the decaying Ge signal between the SiGe and underlying Si. A monotonic increase in apparent layer thickness was found as the energy was reduced across the range 2.5–0.4 keV. However, for beam energies < 0.4 keV, the apparent layer thickness was found to decrease suggesting that an increase in the relative surface‐to‐bulk erosion rate had outweighed any decrease in the true width of the transient region. This effect may be inescapable or caused by a nanometre‐scale Ge rich layer at the surface. The behavior found here shows that the ‘zero beam energy’ profile shape is not necessarily closest to the truth. Copyright © 2010 John Wiley & Sons, Ltd.
The Storing Matter technique: application to polymer samples using Ag collectors
Authors: Becker N. , Wirtz T. , Migeon H.‐N. 
Published: May 2010

AbstractThe Storing Matter technique has been developed to perform quantitative surface analysis with high sensitivity. This technique consists in decoupling the sputtering of the specimen from the subsequent analysis step. In the recently developed prototype instrument, the sample surface is sputtered by an ion beam and the emitted particles are deposited at submonolayer level on a dedicated collector under UHV conditions. In a second step, the matter deposited on the collector is analyzed by SIMS in dynamic or static mode. The chemical nature of the collector surface is chosen with regard to the subsequent SIMS analysis (high or low work function to enhance positive or negative ionization, metallic overlayer for optimized organic information by cationization, etc.) by depositing thin films by electron beam evaporation.This paper presents the first results obtained on polymer samples (PMMA, PVC and PS) with the Storing Matter prototype instrument. The chosen collector surface was Ag, which is known to enhance cationization in static SIMS. The positive mass spectra obtained from Storing Matter deposits on Ag collectors were compared to those recorded on polymer reference samples and on the pristine Ag collectors. This study showed that the Storing Matter technique allows for a clear identification of the PMMA and PVC deposits while enhancing the secondary ion intensities in the higher‐mass range with respect to a conventional static SIMS analysis of the polymer. Copyright © 2010 John Wiley & Sons, Ltd.
Ionization effects in molecular depth profiling of trehalose films using buckminsterfullerene (C60) cluster ions
Authors: Lu C. , Wucher A. , Winograd N. 
Published: May 2010

AbstractSalts play a mysterious role in desorption mass spectrometry, especially in biological samples.1 We used trehalose films doped with a peptide as a well defined model system to investigate the ionization effects in organic molecular depth profiling. Sodium salts at 1% level were added into the solution used to produce the trehalose films, and depth profiles were obtained with a C60 ion source. The results show that the protonated molecular ion signal from the peptide and the quasimolecular ion signal of trehalose are significantly suppressed by the addition of salts, whereas the signals representing salt clusters and salt adducts of trehalose are formed in both positive and negative modes. The formation of protonated molecular ions is found to correlate with the ratio between protonated and bare water ions, suggesting that the latter can be used as an indicator for the accumulation of protons liberated by the ion bombardment. In experiments where no salt was added, it is shown that the surface variation of the protonated molecular ion signal strongly depends upon the water content of the trehalose film. Copyright © 2010 John Wiley & Sons, Ltd.
From FIB‐SIMS to SIMS‐FIB. The prospects for a 10 nm lateral resolution SIMS instrument with full FIB functionality
Authors: McPhail David S. , Li Libing , Chater Richard J. , Yakovlev Nikolai , Seng Hweeleng 
Published: May 2010

AbstractThe FEI FIB (200) SIMS instrument is described herein, and its modes of operation outlined. The issues involved in achieving high lateral resolution analysis with good sensitivity are presented, and some examples of applications in materials science discussed. The possibility of a manufacturer developing a dedicated SIMS‐FIB instrument, i.e. a 10 nm lateral resolution SIMS instrument incorporating an FIB gun and FIB SIMS functionality (analysis, milling and channeling contrast) is explored. Copyright © 2010 John Wiley & Sons, Ltd.
Insight into the swelling mechanism involved in the recovery of serial numbers erased from polymer surfaces
Authors: Conlan Xavier A. , Baker Matthew J. , Krieg Richard , Lockyer Nicholas P. , Vickerman John C. , Barnett Neil W. , Lim Kieran F. 
Published: May 2010

AbstractImaging SIMS is used to investigate the recovery of erased serial numbers from polypropylene, polycarbonate and polyvinylchloride substrates. The recovery of the serial numbers is initiated by a swelling mechanism due to the application of two swelling agents: methyleugenol and cinnamaldehyde. The localization of the characteristic molecular ions for the swelling agents is observed in regions associated with erased characters. This study examines and evaluates SIMS images to discover the optimum combination of the polymer and solvents. The results are discussed in reference to the Hildebrand solubility parameter and comments upon the limitations of this suggested indicator. Copyright © 2010 John Wiley & Sons, Ltd.
In vivo relationship between thalamic nicotinic acetylcholine receptor occupancy rates and antiallodynic effects in a rat model of neuropathic pain: Persistent agonist binding inhibits the expression of antiallodynic effects
Authors: Ueda Masashi , Iida Yasuhiko , Yoneyama Tomoki , Kawai Tomoki , Ogawa Mikako , Magata Yasuhiro , Saji Hideo 
Published: May 2010

AbstractWe have recently clarified that nicotinic acetylcholine receptors (nAChRs) expressed in the thalamus play an important role in antiallodynic effects produced by the nAChR agonist, 5‐iodo‐3‐(2(S)‐azetidinylmethoxy)pyridine (5IA). This study aimed to reveal the in vivo relationship between thalamic nAChR occupancy rates and antiallodynic effects using 5IA and [125I]5IA. We partially ligated the sciatic nerve of a rat to induce neuropathic pain. Antiallodynic effects were evaluated at 15, 30, 60, and 90 min after intracerebroventricular (i.c.v.) administration of multiple doses (1–100 nmol) of 5IA by the von Frey filament test. Receptor occupancy rates were measured by autoradiography at 15 and 90 min after administration. Antiallodynic effects of repetitive treatment of 5IA (5 and 50 nmol) were also examined. A significant and dose‐dependent antiallodynic effect was observed 15 min after administration. It showed a good correlation with receptor occupancy rates (r= 0.97), indicating the binding of 5IA to nAChRs expressed in the thalamus involved in the antiallodynic effect. Five, 50, and 100 nmol of 5IA occupied the thalamic nAChRs until 90 min after administration, while the antiallodynic effect diminished. Five nanomoles of 5IA (which occupied 40% of thalamic nAChRs) showed a significant antiallodynic effect (percentage of the maximal possible effect (%MPE): 35 ± 7) after the second administration, while 50 nmol of 5IA (which occupied 80% of thalamic nAChRs) did not (%MPE: 7 ± 1). These findings suggest that not clearance of 5IA but desensitization of nAChRs caused by persistent binding of 5IA is responsible for the disappearance of antiallodynic effects. Synapse 65:77–83, 2011. © 2010 Wiley‐Liss, Inc.
Enhanced dopamine transporter function in striatum during nicotine withdrawal
Authors: Hadjiconstantinou Maria , Duchemin Anne‐Marie , Zhang Hailing , Neff Norton H. 
Published: May 2010

AbstractSpontaneous and antagonist‐precipitated withdrawal from nicotine is characterized by marked deficits in extracellular dopamine (DA) in striatum, especially in nucleus accumbens, that have been thought to underlie the affective state associated with drug discontinuation. Uptake via the dopamine transporter (DAT) is a key mechanism for regulating the concentrations of extracellular DA. Accordingly, we questioned whether DAT expression and function are altered in striatum in nicotine withdrawal. Male mice, 30–35 g, were injected with nicotine free base 2 mg/kg, s.c., or saline four times daily for 14 days and euthanized 4–72 h after drug discontinuation. DA uptake into striatal synaptosomes was increased 12–24 h into nicotine withdrawal, and accompanied by elevated DAT mRNA in the substantia nigra pars compacta and ventral tegmental area, evaluated by in situ hybridization. The overflow of endogenous DA, measured under basal conditions in striatal slices ex vivo, was decreased during nicotine withdrawal in a time pattern paralleling to that of uptake. Added to striatal slices, the DAT inhibitor nomifensine reduced the observed difference in DA overflow between saline and nicotine withdrawn mice implying a role for the transporter. The presented data suggest that DAT is transiently upregulated in the striatum early during nicotine withdrawal, and enhanced transporter function contributes to the decreased extracellular DA levels. Synapse, 2011. © 2010 Wiley‐Liss, Inc.
Building Opportunity: Developing City Systems to Expand and Improve After School Programs
Authors: Holleman Martha A. , Jane Sundius M. , Bruns Eric J. 
Published: May 2010

AbstractA growing body of research is examining the strengths and weaknesses of specific after school programs and their effect on youth outcomes. Few reviews, however, have sought to examine the components of citywide system‐building—to understand intentional efforts to develop, support and sustain high quality after school programming across a community. Beginning in the mid‐1990s and continuing through the present, private funders, public officials and program practitioners in cities across America have joined together to build systems to support the expansion and improvement of after school programs at the city‐level. This paper presents the community context and underlying principles that drove the development of Baltimore’s After‐School Strategy; articulates a set of system components derived from this experience and the available literature; and lays out future work to expand high quality after‐school opportunities for youth in Baltimore and in other distressed urban environments.
Therapeutic liver repopulation for phenylketonuria
Authors: Harding Cary O. , Gibson K. M. 
Published: May 2010

AbstractProblems with long‐term dietary compliance in phenylketonuria (PKU) necessitate the development of alternative treatment approaches. Therapeutic liver repopulation with phenylalanine hydroxylase (PAH)‐expressing cells following hepatocyte or haematopoietic stem cell transplantation has been investigated as a possible novel treatment approach for PKU. Successful therapeutic liver repopulation requires both a stimulus for liver regeneration at the time of cell transplantation and a selective growth advantage for the PAH+ donor cells. Unfortunately, wild‐type PAH+ hepatocytes do not enjoy any growth advantage over PAH− cells. Successful correction of hyperphenylalaninemia following therapeutic liver repopulation has been accomplished only in an animal model that yields a selective advantage for the donor cells. Haematopoietic stem cell (HSC)‐mediated therapeutic liver repopulation has not been reported in any hyperphenylalaninemic system, and the success of HSC‐mediated liver repopulation for PKU may be limited by the slow kinetics of this approach. If therapeutic liver repopulation is to be employed successfully in humans with PKU, an effective method of providing a selective growth advantage for the donor cells must be developed. If this can be achieved, liver repopulation with 10–20% wild‐type hepatocytes will likely completely normalize Phe clearance in individuals with PKU.