bluuebunny/crossref_metadata_2025 huggingface dataset:
ENHANCED KERR NONLINEARITY IN A FOUR-LEVEL EIT MEDIUM
Authors: SAHRAI M. , ASADPOUR S. H. , SADIGHI R.
Published: October 2010

The linear and nonlinear response of a four-level EIT system driven by three coherent fields is investigated. It is found that at appropriate atomic parameters, the Kerr nonlinearity can clearly be enhanced. It is also demonstrated that the maximal Kerr nonlinearity enters the EIT window, and the corresponding linear and nonlinear absorption suppress. Moreover, we show that nonlinear absorption and Kerr nonlinearity can also be changed via relative phase between driving fields.
NONLINEAR REFRACTION AND PHOTOINDUCED BIREFRINGENCE IN THE METHYL-RED-DOPED POLYMER THIN FILM
Authors: ZHANG XIAOQIANG , WANG CHANGSHUN , ZENG YI , ZHANG JINWEN
Published: October 2010

Single beam Z-scan measurement has shown that the methyl-red-doped PVA thin film possesses a large nonlinear refractive index: n2 ( cm 2/ W ) = -2.29 × 10-4 cm 2/ W and n2 ( cm 2/ W ) = -8.75 × 10-5 cm 2/ W for the CW 532 nm linear polarization light and circular polarization light, respectively. The mechanism for the process of nonlinear refraction is discussed in terms of the photoisomerization of MR molecules. Moreover, photoinduced birefringence with values on the order of 10-4 has been observed when investigating the photoinduced birefringence of the thin film with a CW 532 nm laser as the pump light and a CW 650 nm laser as the probe light.
LOW-POWER ALL-OPTICAL SWITCHING IN A NONLINEAR M–Z INTERFEROMETER MADE FROM A SINGLE-NONLINEAR-FIBER-CONNECTED LPFG PAIR
Authors: ZHANG BING , XU WENCHENG , LI CHUNFEI
Published: October 2010

A new M–Z interferometer all-optical switch (AOS) consisting of a single nonlinear fiber and a linear long-period fiber grating (LPFG) pair is investigated. The switching principle is based on shifting the transmission spectrum over half of the subspectrum width by the pump light. In this paper, two types of such devices are simulated. The first one concerns use of the usual silica fiber based on the Kerr effect, the switching power of which is 471 W, consisting of the experimental result3; the second one concerns the use of an erbium-doped fiber (EDF) based on the resonant nonlinearity, the switching power of which is reduced by less than 25 mW. The transmissions of the AOS in the EDF-LPFG pair for different parameters of LPFG are also discussed.
TUNABLE TRANSMISSION USING AZO-DYE-DOPED AMORPHOUS POLYMER FILMS
Authors: FAN SHENGFA , ZHU JIANGZHUAN , SHEN DONG , GU YINGJUN , GU XIAOYAN , LUO DUANBIN
Published: October 2010

The photoinduced birefringence effect in a type of azo-dye-doped poly (methyl methacrylate) was realized when it was pumped by a polarized argon ion laser beam. The transmission of a 632.8 nm probe beam through the pumped sample could be controlled by two kinds of methods: one employed the photoinduced thermal effect of the pump light in the azo-dye-containing sample, and the other changed the temperature of the sample directly. The tunable transmission of the probe light with different pump power and at various temperatures of the sample was investigated in detail.
THIRD-ORDER NONLINEAR OPTICAL INVESTIGATION OF A NOVEL MATERIAL IN THE NEAR-IR REGIONS
Authors: WANG YAN-LING , JIANG GUAN-CHENG , WANG YE-FEI , ZHENG JING-JING , LI MA
Published: October 2010

The third-order nonlinearity of a novel ET[bis(ethylenedithio)-tetrathiafulvalene] complex (ET ⋅ BF3) has been measured by using the Z-scan technique with a laser pulse width of 30 ps at 1064 nm. The third-order nonlinear refractive index (n2), nonlinear absorption coefficient (β) and nonlinear susceptibilities (χ(3)) of a sample acetonitrile solution are 3.5 × 10-11 esu, 1.65 cm/GW and 5.4 × 10-12 esu, respectively. The nonresonant second-order hyperpolarizability (γ) for the molecule has been estimated to be 2.77 × 10-30 esu. The two merit factors for all-optical switching are W ≫ 1 and T = 1.49, respectively.
A NEW TRAFFIC SPEED FORECASTING METHOD BASED ON BI-PATTERN RECOGNITION
Authors: WANG JING , SHANG PENGJIAN , ZHAO XIAOJUN
Published: October 2010

Short-term traffic forecasting has played a key role in supporting the need of proactive and dynamic traffic control system. K-nearest neighbor (KNN) nonparametric regression models have been widely used in traffic prediction. KNN models give predictions based on the future state of traffic speed that is completely determined by the current state, but with no dependence on the past sequences of traffic speed that produced the current state. In fact, traffic speed is not completely random in nature, and some patterns repeat in the traffic stream. In this paper, we proposed a methodology called bi-pattern recognition KNN model (BKNN) which uses pattern recognition technique twice in the searching process to predict the future traffic state. Then the proposed BKNN model is applied to predict one day real traffic speed series of two sites, which are located near the North 2nd and 3rd Ring Road in Beijing, respectively. With the optimal neighbor and pattern size, the BKNN model provides good predictions. Moreover, in comparison with the KNN model, PKNN model (a modified model based on KNN), seasonal autoregressive integrated moving average (SARIMA) and the artificial neural networks (ANN), the BKNN model appears to be the most promising and robust of the five models to provide better short-term traffic prediction.
GAME-MODEL RESEARCH ON COOPETITION BEHAVIOR OF PARRONDO'S PARADOX BASED ON NETWORK
Authors: WANG LIN-GANG , XIE NENG-GANG , XU GANG , WANG CHAO , CHEN YUN , YE YE
Published: October 2010

The paper devises a Parrondo's game model of biotic population with the network as its spatial carrier, trying to analyze individual's coopetition behavior and investigate the degree distribution of the heterogeneity on the impact of coopetition. The populational Parrondo's game model consists of a zero-sum game among individuals and a negative sum game between individuals and environment. In terms of relations of zero-sum game, four patterns are defined: cooperation, competition, harmony, and poor-competition-rich-cooperation. The simulation result shows that: (1) Cooperation and competition in any forms are adaptive behaviors. Cooperative and competitive behavior could convert the losing games combined into winning. The positive average fitness of the population represents the paradoxical feature that the Parrondo's game is counterintuitive. (2) BA Network is conducive to cooperation. (3) The relationships of individual fitness with node degree and with clustering coefficient are disclosed. As for cooperation and poor-competition-rich-cooperation pattern, the greater the node degree is, the greater the individual fitness is. (4) The heterogeneity has a positive impact on cooperation. (5) Population average fitness is the largest when the probability of playing zero-sum game is 1/3 in the Parrondo's game model.
HARD TEMPLATES FOR FABRICATION OF NANOSTRUCTURED FILMS
Authors: LEE KI-RIM , KWON YOUNG-UK
Published: October 2010

In this paper, we review on classes of materials that can be used as hard templates to fabricate nanostructured thin film materials. The hard templates discussed are anodized aluminum oxide (AAO), block copolymer (BC) self-assembly films, and mesoporous thin films (MTFs), with emphasis on MTFs since it has not been reviewed for the application as templates while the first two materials have been reviewed previously by others. Each one of the three classes of templates has advantages and drawbacks. Considering the pore dimensions available by each one of them, the three templates are complementary to one another. Some of the features of MTFs appear to be advantageous over the other types of templates. All and all, these three appear to have complementing features to cover the various aspects required for templates to synthesize nanostructured thin films.
SYNTHESIS AND CHARACTERIZATION OF CdS NANOCRYSTALLITES DISPERSED IN POLYMER MATRIX
Authors: SINHA O. P. , SRIVASTAVA RITU , SHRIPATHI T.
Published: October 2010

Cadmium sulphide (CdS) nanocrystallites were prepared by sulphuration route with capping in polyethylene oxide (PEO) polymer matrix. It is found that PEO could provide a confined environment for particle nucleation and growth of CdS nanocrystallites. The scanning electron microscopy (SEM) with energy dispersive analysis by X-ray (EDAX) studies confirms the presence of CdS nanocrystallites in polymer matrix. X-ray diffraction (XRD) studies and transmission electron microscopy (TEM) selected area diffraction (SAD) patterns show that these crystallites have hexagonal structure. The TEM and UV-Visible absorption studies indicate uniform size distribution having size around 2.3 nm and band gap of 2.7 eV. X-ray photoelectron spectroscopy (XPS) studies reveal that core level energy positions of the Cd is shifted towards the lower binding energy and has similar chemical environment to that of bulk CdS .
DISPERSION OF PRISTINE MULTI-WALLED CARBON NANOTUBES IN COMMON ORGANIC SOLVENTS
Authors: SUN GUOXING , LIU ZHENGPING , CHEN GUANGMING
Published: October 2010

The dispersion of pristine multi-walled carbon nanotubes in various common organic solvents and water has been investigated. Sedimentation tests, optical microscopy, transmission electron microscopy and Tyndall effect tests are employed. The results clearly show that N-methyl-2-pyrrolodone, acetone, tetrahydrofuran and dichloromethane are good solvents to debundle and disperse the multi-walled carbon nanotubes. In contrast, much precipitation can be obviously observed for systems of the carbon nanotubes in water, ethanol and toluene. Additionally, Tyndall effect tests suggest that the upper dispersions of the carbon nanotubes in acetone, tetrahydrofuran and dichloromethane with a concentration of 0.1 mg/mL and the dispersion of carbon nanotubes in N-methyl-2-pyrrolodone with a concentration of 0.05 mg/mL are colloidal systems rather than solutions. Finally, based on the above results, a possible mechanism is briefly discussed.
AFM, HR-XRD AND PL CHARACTERIZATION OF STACKED STRUCTURES In0.5Ga0.5As/GaAs QUANTUM DOTS
Authors: ARYANTO DIDIK , OTHAMAN ZULKAFLI , AMERUDDIN AMIRA S. , ISMAIL ABD. KHAMIM
Published: October 2010

In0.5Ga0.5As quantum dots (QDs) stacked structure were studied using atomic force microscopy (AFM), high-resolution X-ray diffraction (HR-XRD) and photoluminescence (PL) characterization. Evolution in the dots size and dots density in the stacked structures is strongly influenced by the dot formation in the under-layer and the structure of the spacer layers. AFM results revealed that the dots formation on the top can be changed by increasing the number of stacked QDs. However, the dots formation is not vertically aligned since HR-XRD measurement gave different satellite peak on n-stacked QD structures. Room-temperature PL measurements show variation in the PL spectra, where blue-shifted PL peak positions are observed when the number of stack is increased. Variation in the HR-XRD and PL measurement is also attributed to the size, composition and density of the dots in the stacked structures.
Rethinking the systems review process
Authors: Lau Tessa
Published: October 2010

http://cacm.acm.org/blogs/blog-cacm

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Web site, http://cacm.acm.org, features more than a dozen bloggers in the BLOG@CACM community. In each issue of
Communications
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Tessa Lau launches a discussion about the acceptance criteria for HCI systems papers at CHI, UIST, and other conferences.
Turning data into knowledge
Authors: Goth Gregory
Published: October 2010

Today's data deluge is leading to new approaches to visualize, analyze, and catalog enormous datasets.
Security in the cloud
Authors: Anthes Gary
Published: October 2010

Cloud computing offers many advantages, but also involves security risks. Fortunately, researchers are devising some ingenious solutions.
The divergent online news preferences of journalists and readers
Authors: Boczkowski Pablo J.
Published: October 2010

Reading between the lines of the thematic gap between the supply and demand of online news.
Why do software startups patent (or not)?
Authors: Samuelson Pamela
Published: October 2010

Assessing the controversial results of a recent empirical study of the role of intellectual property in software startups.
Keeping bits safe
Authors: Rosenthal David S. H.
Published: October 2010

As storage systems grow larger and larger, protecting their data for long-term storage is becoming ever more challenging.
Understanding throughput-oriented architectures
Authors: Garland Michael , Kirk David B.
Published: October 2010

For workloads with abundant parallelism, GPUs deliver higher peak computational throughput than latency-oriented CPUs.
Regulating the information gatekeepers
Authors: Vogl Patrick , Barrett Michael
Published: October 2010

Concerns about biased manipulation of search results may require intervention involving government regulation.
Using complexity to protect elections
Authors: Faliszewski Piotr , Hemaspaandra Edith , Hemaspaandra Lane A.
Published: October 2010

Computational complexity may truly be the shield against election manipulation.
In support of computer science teachers and the CSTA
Authors: Buell Duncan
Published: October 2010

A number of recent articles and comments have discussed the imbalance between enrollment and opportunities in computer science and the under-enrollments by minorities and women. An ongoing thread in Peter Denning's
Communications
columns and elsewhere concerns the identity of the discipline to which we belong. As the national representative from universities to the board of the Computer Science Teachers Association (CSTA), I continually see the question of the identity of our discipline both within and external to our field.

The identity of computer science is nowhere more important to the discipline of computer science than in the K--12 school system. We can instruct our own students in the nature of the discipline, but those we so instruct will only be those who first choose to come to us. If we want more students, and if we want to be understood for what we are, we must clarify the message about computer science that all students will receive as part of their K--12 education.

Even if one does not believe that "computer science" should be taught in the K--12 system (and I know there are those who hold that opinion), it is nonetheless necessary for us to be involved in defining for the schools that which is called "computer science." There
will
be courses in Photoshop, Web design, office tools, A+ certification, networking, and such, and there
will
be (a smaller number of) courses in Visual Basic, C++, or even Java. The simple fact is that these courses will exist in the schools, and there is nothing fundamentally wrong with that. What is a problem is for students to be misled into thinking that these are all indistinguishable and all equally describable as "computer science." The burden rests with us in the discipline to educate those who administer the schools and to urge the adoption by the schools of a relevant curriculum that meets the needs of the K--12 system but that is computer science as seen by computer scientists.

There are efforts in this direction, and we should be giving them active support. The CSTA has a model curriculum for high school and is developing curricula for the lower grades. CSTA and ACM have sponsored, with NSF funding, a "leadership cohort" of teachers in all the states as a way to bootstrap a network of teachers who can, among other things, speak as a group with a coherent voice about policy. And the ACM Education Policy Committee provides a voice from ACM in which all of us in the discipline have a stake. We have come more recently to this than, say, biology or mathematics, but the machinery now exists for computing practitioners and teachers to speak to those whose administrative decisions outside our discipline have a major impact on us. A
Communications
Viewpoints contribution by Wilson and Harsha (September 2009) provides a summary of status and progress.
How Government Policy Drives e-Learning
Authors: Rowell Laurie
Published: October 2010

Educators spend their lives on the tactics of education, but ultimately, they don't get to devise the grand strategy. Education is shaped by legislators and agencies that create public policy, which determine how technological tools will be used in education. Unfortunately, the development and implementation of government policy can't match the ever-accelerating speed of technological innovation. This creates a challenge for policymakers, who must try to write policy that won't become outdated before the metaphorical ink is dry. In this in-depth eLearn Magazine exclusive, journalist Laurie Rowell speaks with a number of policy makers about how this system works -- and why it often doesnt work.
Holding the Virtual Self Accountable
Authors: Hicks Brett
Published: October 2010

Student accountability is paramount, says Brett Hicks in a new op-ed. In order for distance education institutions to overcome the stigma of online education, faculty must act as gatekeepers, protecting the integrity of their respective institutions. This defense begins in the classroom. Distance education institutions distinguish themselves in the same manner as traditional institutions of higher learning. They produce educated, student professionals -- even virtual ones
Electrochemical Biosensor Utilizing Nitrogen Incorporated Nanodiamond Ultra-Microelectrode Array
Authors: Raina Supil , Kang W. P. , Davidson J. L. , Huang Jin-Hua
Published: October 2010

A nitrogen incorporated nanodiamond ultra-microelectrode array was fabricated using silicon microfabrication technology and microwave PECVD process. 400 ultra-microelectrodes, which are arranged in a square array, project above the surrounding plane of the SiO2 insulation layer. Each ultra-microelectrode has a radius of 5µm and a spacing of 100µm, in order to avoid an overlap of individual diffusion layers. Dopamine (DA), which is an important catecholamine neurotransmitter, can be detected by the UMEA using steady state cyclic voltammetry with a linear dynamic range of 100µM-1mM. Even though Ascorbic acid (AA) interferes with DA detection under real physiological conditions, we are able to extract the calibration curve for different DA concentrations in the presence of 1mM AA without the need of any surface modification.
Nanofabrication of Robust Nanoelectrodes for Electrochemical Applications
Authors: Dawson Karen , Strutwolf Jorg , Herzog Gregorie , Arrigan Damien , Quinn Aidan , O'Riordan Alan J.
Published: October 2010

Individual gold nanowire devices for use as nanoelectrodes in electrochemical studies were fabricated using a low-cost robust fabrication approach. Nanowires were characterized by a combination of direct electrical current-voltage measurements and cyclic voltammetry using the model analyte ferrocene monocarboxylic acid. We observed low electrical resistances to contacted nanowires and steady-state sigmoidal electrochemical voltammograms that may be described by classical Butler-Volmer kinetics. The potential of nanowires for use in future biosensing applications was explored by demonstrating mediated bioelectrocatalytic oxidation of glucose.
Contribution of Kir2 potassium channels to ATP-induced cell death in brain capillary endothelial cells and reconstructed HEK293 cell model
Authors: Yamazaki Daiju , Kito Hiroaki , Yamamoto Seiji , Ohya Susumu , Yamamura Hisao , Asai Kiyofumi , Imaizumi Yuji
Published: October 2010

Cellular turnover of brain capillary endothelial cells (BCECs) by the balance of cell proliferation and death is essential for maintaining the homeostasis of the blood-brain barrier. Stimulation of metabotropic ATP receptors (P2Y) transiently increased intracellular Ca2+concentration ([Ca2+]i) in t-BBEC 117, a cell line derived from bovine BCECs. The [Ca2+]irise induced membrane hyperpolarization via the activation of apamin-sensitive small-conductance Ca2+-activated K+channels (SK2) and enhanced cell proliferation in t-BBEC 117. Here, we found anomalous membrane hyperpolarization lasting for over 10 min in response to ATP in ∼15% of t-BBEC 117, in which inward rectifier K+channel (Kir2.1) was extensively expressed. Once anomalous hyperpolarization was triggered by ATP, it was removed by Ba2+but not by apamin. Prolonged exposure to ATPγS increased the relative population of t-BBEC 117, in which the expression of Kir2.1 mRNAs was significantly higher and Ba2+-sensitive anomalous hyperpolarization was observed. The cultivation of t-BBEC 117 in serum-free medium also increased this population and reduced the cell number. The reduction of cell number was enhanced by the addition of ATPγS and the enhancement was antagonized by Ba2+. In the human embryonic kidney 293 cell model, where SK2 and Kir2.1 were heterologously coexpressed, [Ca2+]irise by P2Y stimulation triggered anomalous hyperpolarization and cell death. In conclusion, P2Y stimulation in BCECs enhances cell proliferation by SK2 activation in the majority of cells but also triggers cell death in a certain population showing a substantial expression of Kir2.1. This dual action of P2Y stimulation may effectively facilitate BCEC turnover.
Posttranscriptional mechanisms involving microRNA-27a and b contribute to fast-specific and glucocorticoid-mediated myostatin expression in skeletal muscle
Authors: Allen David L. , Loh Amanda S.
Published: October 2010

Expression of the antigrowth factor myostatin (MSTN) differs between fast and slow skeletal muscles and is increased in nearly every form of muscle atrophy, but the contribution of transcriptional vs. posttranscriptional mechanisms to its differing expression in these states has not been defined. We show here that levels of mature MSTN mRNA were sixfold greater in fast vs. slow muscle and were increased twofold in fast muscle in response to dexamethasone (Dex) injection in vivo and in C2C12 myotubes following Dex treatment in vitro, but that levels of MSTN pre-mRNA, a readout of transcription, only minimally and nonsignificantly differed in these states. Moreover, Dex treatment with or without cotransfection with a glucocorticoid receptor expression construct had only modest effects on mouse MSTN promoter activity in C2C12 myotubes. We therefore explored the potential contribution of posttranscriptional mechanisms, and the role of the microRNAs miR-27a and b in particular, on MSTN expression. The MSTN 3′-untranslated region (UTR) contains a putative recognition sequence for miR-27a and b that is conserved across a wide range of vertebrate species. Cotransfection of a MSTN 3′-UTR-luciferase construct with a miR-27b expression construct significantly attenuated by approximately half while mutation of the miR-27 recognition sequence significantly increased by approximately twofold the activity of a MSTN 3′-UTR construct and decreased mRNA degradation of a luciferase reporter construct in C2C12 myotubes. Expression of miR-27a and b was almost sixfold greater in slow-twitch than in fast-twitch muscle in vivo, and miR-27a expression was significantly decreased by nearly half by glucocorticoid treatment in vitro. Finally, the miR-27a and b promoters were activated by cotransfection with the slow-specific signaling molecules calcineurin and peroxisome proliferator-activated receptor-γ coactivator-1α. The present data represent the first demonstration that posttranscriptional mechanisms involving miR-27a and b may contribute to fast-specific and glucocorticoid-dependent myostatin expression in muscle.
High glucose causes dysfunction of the human glomerular endothelial glycocalyx
Authors: Singh A. , Fridén V. , Dasgupta I. , Foster R. R. , Welsh G. I. , Tooke J. E. , Haraldsson B. , Mathieson P. W. , Satchell S. C.
Published: October 2010

The endothelial glycocalyx is a gel-like layer which covers the luminal side of blood vessels. The glomerular endothelial cell (GEnC) glycocalyx is composed of proteoglycan core proteins, glycosaminoglycan (GAG) chains, and sialoglycoproteins and has been shown to contribute to the selective sieving action of the glomerular capillary wall. Damage to the systemic endothelial glycocalyx has recently been associated with the onset of albuminuria in diabetics. In this study, we analyze the effects of high glucose on the biochemical structure of the GEnC glycocalyx and quantify functional changes in its protein-restrictive action. We used conditionally immortalized human GEnC. Proteoglycans were analyzed by Western blotting and indirect immunofluorescence. Biosynthesis of GAG was analyzed by radiolabeling and quantified by anion exchange chromatography. FITC-albumin was used to analyze macromolecular passage across GEnC monolayers using an established in vitro model. We observed a marked reduction in the biosynthesis of GAG by the GEnC under high-glucose conditions. Further analysis confirmed specific reduction in heparan sulfate GAG. Expression of proteoglycan core proteins remained unchanged. There was also a significant increase in the passage of albumin across GEnC monolayers under high-glucose conditions without affecting interendothelial junctions. These results reproduce changes in GEnC barrier properties caused by enzymatic removal of heparan sulfate from the GEnC glycocalyx. They provide direct evidence of high glucose-induced alterations in the GEnC glycocalyx and demonstrate changes to its function as a protein-restrictive layer, thus implicating glycocalyx damage in the pathogenesis of proteinuria in diabetes.
Connecting chronic and recurrent stress to vascular dysfunction: no relaxed role for the renin-angiotensin system
Authors: Groeschel Michael , Braam Branko
Published: October 2010

The renin-angiotensin system (RAS) is classically considered to be a protective system for volume balance and is activated during states of volume depletion. Interestingly, one of the major pathways activating the system is the sympathetic nervous system, also the primary mediator of the acute stress response. When one further examines the cells mediating the immune site of the response, which is primarily an inflammatory response leading to defense at a locally injured area, these cells all express the ANG II type 1 receptor (AGTR1). Scattered throughout the literature are reports indicating that acute and chronic stress can activate renin and increase plasma levels of components of the RAS. Moreover, there are reports describing that ANG II can modulate the distribution and function of immune cells. Since the inflammatory response is also implicated to be central in the initiation and progression of vascular damage, we propose in this review that recurrent acute stress and chronic stress can induce a state with inflammation, due to ANG II-mediated activation of inflammatory cells, specifically monocytes and lymphocytes. Such a proposal would explain a lot of the observations regarding RAS components in inflammatory cells. Despite its attractiveness, substantial research in this area would be required to substantiate this hypothesis.
Phasic and Tonic Patterns of Locus Coeruleus Output Differentially Modulate Sensory Network Function in the Awake Rat
Authors: Devilbiss David M. , Waterhouse Barry D.
Published: October 2010

Neurons of the nucleus locus coeruleus (LC) discharge with phasic bursts of activity superimposed on highly regular tonic discharge rates. Phasic bursts are elicited by bottom-up input mechanisms involving novel/salient sensory stimuli and top-down decision making processes; whereas tonic rates largely fluctuate according to arousal levels and behavioral states. Although it is generally believed that these two modes of activity differentially modulate information processing in LC targets, the unique role of phasic versus tonic LC output on signal processing in cells, circuits, and neural networks of waking animals is not well understood. In the current study, simultaneous recordings of individual neurons within ventral posterior medial thalamus and barrel field cortex of conscious rats provided evidence that each mode of LC output produces a unique modulatory impact on single neuron responsiveness to sensory-driven synaptic input and representations of sensory information across ensembles of simultaneously recorded cells. Each mode of LC activation specifically modulated the relationship between sensory-stimulus intensity and the subsequent responses of individual neurons and neural ensembles. Overall these results indicate that phasic versus tonic modes of LC discharge exert fundamentally different modulatory effects on target neuronal circuits within the rodent trigeminal somatosensory system. As such, each mode of LC output may differentially influence signal processing as a means of optimizing behaviorally relevant neural computations within this sensory network. Likely the ability of the LC system to differentially regulate neural responses and local circuit operations according to behavioral demands extends to other brain regions including those involved in higher cognitive functions.
Area MSTd Neurons Encode Visual Stimuli in Eye Coordinates During Fixation and Pursuit
Authors: Lee Brian , Pesaran Bijan , Andersen Richard A.
Published: October 2010

Visual signals generated by self-motion are initially represented in retinal coordinates in the early parts of the visual system. Because this information can be used by an observer to navigate through the environment, it must be transformed into body or world coordinates at later stations of the visual-motor pathway. Neurons in the dorsal aspect of the medial superior temporal area (MSTd) are tuned to the focus of expansion (FOE) of the visual image. We performed experiments to determine whether focus tuning curves in area MSTd are represented in eye coordinates or in screen coordinates (which could be head, body, or world-centered in the head-fixed paradigm used). Because MSTd neurons adjust their FOE tuning curves during pursuit eye movements to compensate for changes in pursuit and translation speed that distort the visual image, the coordinate frame was determined while the eyes were stationary (fixed gaze or simulated pursuit conditions) and while the eyes were moving (real pursuit condition). We recorded extracellular responses from 80 MSTd neurons in two rhesus monkeys ( Macaca mulatta). We found that the FOE tuning curves of the overwhelming majority of neurons were aligned in an eye-centered coordinate frame in each of the experimental conditions [fixed gaze: 77/80 (96%); real pursuit: 77/80 (96%); simulated pursuit 74/80 (93%); t-test, P < 0.05]. These results indicate that MSTd neurons represent heading in an eye-centered coordinate frame both when the eyes are stationary and when they are moving. We also found that area MSTd demonstrates significant eye position gain modulation of response fields much like its posterior parietal neighbors.
Local-Distributed Integration by a Novel Neuron Ensures Rapid Initiation of Animal Locomotion
Authors: Mullins Olivia J. , Hackett John T. , Friesen W. Otto
Published: October 2010

Animals are adapted to respond quickly to threats in their environment. In many invertebrate and some vertebrate species, the evolutionary pressures have resulted in rapidly conducting giant axons, which allow short response times. Although neural circuits mediating escape behavior are identified in several species, little attention has been paid to this behavior in the medicinal leech, a model organism whose neuronal circuits are well known. We present data that suggest an alternative to giant axons for the rapid initiation of locomotion. A novel individual neuron, cell E21, appears to be one mediator of this short-latency action in the leech. In isolated nerve cord and semi-intact preparations, cell E21 excitation initiates and extends swimming and reduces the cycle period. The soma of this cell is located caudally, but its axon extends nearly the entire length of the nerve cord. We found that cell E21 fires impulses following local sensory inputs anywhere along the body and makes excitatory synapses onto the gating cells that drive swimming behavior. These distributed input–output sites minimize the distance information travels to initiate swimming behavior, thus minimizing the latency between sensory input and motor output. We propose that this single cell E21 functions to rapidly initiate or modulate locomotion through its distributed synaptic connections.
Motoneuron Excitability and Muscle Spasms Are Regulated by 5-HT2Band 5-HT2CReceptor Activity
Authors: Murray Katherine C. , Stephens Marilee J. , Ballou Edmund W. , Heckman Charles J. , Bennett David J.
Published: October 2010

Immediately after spinal cord injury (SCI), a devastating paralysis results from the loss of brain stem and cortical innervation of spinal neurons that control movement, including a loss of serotonergic (5-HT) innervation of motoneurons. Over time, motoneurons recover from denervation and function autonomously, exhibiting large persistent calcium currents (Ca PICs) that both help with functional recovery and contribute to uncontrolled muscle spasms. Here we systematically evaluated which 5-HT receptor subtypes influence PICs and spasms after injury. Spasms were quantified by recording the long-lasting reflexes (LLRs) on ventral roots in response to dorsal root stimulation, in the chronic spinal rat, in vitro. Ca PICs were quantified by intracellular recording in synaptically isolated motoneurons. Application of agonists selective to 5-HT2Band 5-HT2Creceptors (including BW723C86) significantly increased the LLRs and associated Ca PICs, whereas application of agonists to 5-HT1, 5-HT2A, 5-HT3, or 5-HT4/5/6/7receptors (e.g., 8-OH-DPAT) did not. The 5-HT2receptor agonist–induced increases in LLRs were dose dependent, with doses for 50% effects (EC50) highly correlated with published doses for agonist receptor binding ( Ki) at 5-HT2Band 5-HT2Creceptors. Application of selective antagonists to 5-HT2B(e.g., RS127445) and 5-HT2C(SB242084) receptors inhibited the agonist-induced increase in LLR. However, antagonists that are known to specifically be neutral antagonists at 5-HT2B/Creceptors (e.g., RS127445) had no effect when given by themselves, indicating that these receptors were not activated by residual 5-HT in the spinal cord. In contrast, inverse agonists (such as SB206553) that block constitutive activity at 5-HT2Bor 5-HT2Creceptors markedly reduced the LLRs, indicating the presence of constitutive activity in these receptors. 5-HT2Bor 5-HT2Creceptors were confirmed to be on motoneurons by immunolabeling. In summary, 5-HT2Band 5-HT2Creceptors on motoneurons become constitutively active after injury and ultimately contribute to recovery of motoneuron function and emergence of spasms.
Mechanism of Resource Virtualization in RCS for Multitask Stream Applications
Authors: Kirischian L. , Dumitriu V. , Chun P. W. , Okouneva G.
Published: October 2010

Virtualization of logic, routing, and communication resources in recent FPGA devices can provide a dramatic improvement in cost-efficiency for reconfigurable computing systems (RCSs). The presented work is “proof-of-concept” research for the virtualization of the above resources in partially reconfigurable FPGA devices with a tile-based architecture. The following aspects have been investigated, prototyped, tested, and analyzed: (i) platform architecture for hardware support of the dynamic allocation of Application Specific Virtual Processors (ASVPs), (ii) mechanisms for run-time on-chip ASVP assembling using virtual hardware Components (VHCs) as building blocks, and (iii) mechanisms for dynamic on-chip relocation of VHCs to predetermined slots in the target FPGA. All the above mechanisms and procedures have been implemented and tested on a prototype platform—MARS (multitask adaptive reconfigurable system) using a Xilinx Virtex-4 FPGA. The on-chip communication infrastructure has been developed and investigated in detail, and its timing and hardware overhead were analyzed. It was determined that component relocation can be done without affecting the ASVP pipeline cycle time and throughput. The hardware overhead was estimated as relatively small compared to the gain of other performance parameters. Finally, industrial applications associated with next generation space-borne platforms are discussed, where the proposed approach can be beneficial.
Free Vibration of Layered Circular Cylindrical Shells of VariableThickness Using Spline Function Approximation
Authors: Viswanathan K. K. , Kim Kyung Su , Lee Kyung Ho , Lee Jang Hyun
Published: October 2010

Free vibration of layered circular cylindrical shells of variable thickness is studied
using spline function approximation by applying a point collocation method. The shell is
made up of uniform layers of isotropic or specially orthotropic materials. The equations
of motions in longitudinal, circumferential and transverse displacement components, are
derived using extension of Love′s first approximation theory. The coupled differential
equations are solved using Bickley‐type splines of suitable order, which are cubic and
quintic, by applying the point collocation method. This results in the generalized
eigenvalue problem by combining the suitable boundary conditions. The effect of
frequency parameters and the corresponding mode shapes of vibration are studied with
different thickness variation coefficients, and other parameters. The thickness variations
are assumed to be linear, exponential, and sinusoidal along the axial direction. The results
are given graphically and comparisons are made with those results obtained using finite
element method.
Ultrasonic Measurement of Body Fat as a Means of Assessing Body Condition in Free-Ranging Raccoons (Procyon lotor)
Authors: Stringer Elizabeth M. , Stoskopf Michael K. , Simons Theodore , O'Connell Allan F. , Waldstein Arielle
Published: October 2010

Assessment of body condition of free-ranging animals is important when evaluating population health and fitness. The following study used body condition scoring, ultrasound, and dissected physical measurement to assess fat stores in free-ranging raccoons (Procyon lotor). Measurements were taken of subcutaneous fat at interscapular, thoracolumbar, and lumbosacral paraspinal and ventral midline sites. These measurements were examined in relationship to body condition scores and body weight. The ultrasound technique accurately measured the subcutaneous fat of raccoons when compared to dissected physical measurement and yielded data that strongly correlated with both body condition score and body weight, with the ventral midline measurement most strongly correlated. This noninvasive method may be useful in conjunction with body condition score and body weight when assessing the nutritional status of raccoons and potentially other small carnivore species.
Automatic Graph Cut Segmentation of Lesions in CT Using Mean Shift Superpixels
Authors: Ye Xujiong , Beddoe Gareth , Slabaugh Greg
Published: October 2010

This paper presents a new, automatic method of accurately extracting lesions from CT data. It first determines, at each voxel, a five‐dimensional (5D) feature vector that contains intensity, shape index, and 3D spatial location. Then, nonparametric mean shift clustering forms superpixels from these 5D features, resulting in an oversegmentation of the image. Finally, a graph cut algorithm groups the superpixels using a novel energy formulation that incorporates shape, intensity, and spatial features. The mean shift superpixels increase the robustness of the result while reducing the computation time. We assume that the lesion is part spherical, resulting in high shape index values in a part of the lesion. From these spherical subregions, foreground and background seeds for the graph cut segmentation can be automatically obtained. The proposed method has been evaluated on a clinical CT dataset. Visual inspection on different types of lesions (lung nodules and colonic polyps), as well as a quantitative evaluation on 101 solid and 80 GGO nodules, both demonstrate the potential of the proposed method. The joint spatial‐intensity‐shape features provide a powerful cue for successful segmentation of lesions adjacent to structures of similar intensity but different shape, as well as lesions exhibiting partial volume effect.
New Strategies for the Next Generation of Matrix-Metalloproteinase Inhibitors: Selectively Targeting Membrane-Anchored MMPs with Therapeutic Antibodies
Authors: Devy Laetitia , Dransfield Daniel T.
Published: October 2010

MMP intervention strategies have met with limited clinical success due to severe toxicities. In particular, treatment with broad-spectrum MMP-inhibitors (MMPIs) caused musculoskeletal pain and inflammation. Selectivity may be essential for realizing the clinical potential of MMPIs. Here we review discoveries pinpointing membrane-bound MMPs as mediators of mechanisms underlying cancer and inflammation and as possible therapeutic targets for prevention/treatment of these diseases. We discuss strategies to target these therapeutic proteases using highly selective inhibitory agents (i.e., human blocking antibodies) against individual membrane-bound MMPs.
Cognitive-Behavioral Strategies to Increase the Adherence to Exercise in the Management of Obesity
Authors: Dalle Grave Riccardo , Calugi Simona , Centis Elena , El Ghoch Marwan , Marchesini Giulio
Published: October 2010

Physical activity plays a major role in the development and management of obesity. High levels of physical activity provide an advantage in maintaining energy balance at a healthy weight, but the amount of exercise needed to produce weight loss and weight loss maintenance may be difficult to achieve in obese subjects. Barriers to physical activity may hardly be overcome in individual cases, and group support may make the difference. The key role of cognitive processes in the failure/success of weight management suggests that new cognitive procedures and strategies should be included in the traditional behavioral treatment of obesity, in order to help patients build a mindset of long-term weight control. We reviewed the role of physical activity in the management of obesity, and the principal cognitive-behavioral strategies to increase adherence to exercise. Also in this area, we need to move from the traditional prescriptive approach towards a multidisciplinary intervention.
Downregulation of c-MYC Protein Levels Contributes to Cancer Cell Survival under Dual Deficiency of Oxygen and Glucose
Authors: Okuyama Hiroaki , Endo Hiroko , Akashika Tamaki , Kato Kikuya , Inoue Masahiro
Published: October 2010

The c-MYC protein participates in energy-consuming processes such as proliferation and ribosome biosynthesis, and its expression is often dysregulated in human cancers. Cancer cells distant from blood vessels in solid tumors are in short supply of oxygen and nutrition yet can adapt to the microenvironment and survive under metabolic stress. The role and regulation of c-MYC protein in the tumor microenvironment of limited energy sources are poorly understood. Here, we show that c-MYC protein levels in cancer cells are strikingly reduced in the area distant from the blood vessels in vivo and also under oxygen- and glucose-deprived conditions in vitro. The rapid reduction of c-MYC protein levels requires low levels of both oxygen and glucose, and under these conditions, downregulation is mainly achieved by enhanced degradation. Suppression of c-MYC protein levels by small hairpin RNA decreases the necrotic cell death induced by oxygen and glucose deprivation. Thus, the environmental milieu regulates c-MYC protein levels, and downregulation of c-MYC might be a strategy for cancer cells to survive under conditions of limited energy sources. Cancer Res; 70(24); 10213–23. ©2010 AACR.
Management of the Distal Ureter during Nephroureterectomy for Upper Urinary Tract Transitional Cell Carcinoma: A Review
Authors: Gkougkousis Evangelos G. , Mellon J. Kilian , Griffiths T.R. Leyshon
Published: October 2010

Introduction: The standard treatment for upper urinary tract transitional cell carcinoma (UUT-TCC) is open radical nephroureterectomy with excision of a bladder cuff. We assess the successful endoscopic completion and oncological efficacy of the various minimally invasive transurethral techniques devised for the management of the intramural ureter during nephroureterectomy. Materials and Methods: A comprehensive review of the English literature until February 2009 using the PubMed database returned 42 relevant papers. Five methods of endoscopic management of the distal ureter were identified and compared to the open technique. Results: There are no randomised studies. Successful completion of the endoscopic procedure was less (91%) for the ureteric stripping technique than for the other endoscopic modalities (99.8–100%). Recurrences were highest for laparoscopic extravesical ureteric stapling in conjunction with cystoscopic detachment of the ureter, although the numbers analysed were small. For the other endoscopic modalities, bladder recurrence, positive margins and retroperitoneal recurrence (20–37, 0–4 and 1–3%, respectively) in case series were similar compared with the open method (36, 5 and 3%, respectively). Conclusions: Current non-randomised evidence is open to selection bias and is insufficient to support or refute endoscopic management of the distal ureter as an alternative to open bladder cuff excision. We highlight the reported inefficiency of the ureteric stripping technique.
Ureteral Double-J Wire Stent Effectiveness after Endopyelotomy: An Animal Model Study
Authors: Soria Federico , Delgado M. Inmaculada , Rioja Luis Ángel , Blas Miguel , Pamplona Manuel , Durán Esther , Usón Jesús , Sánchez Francisco M.
Published: October 2010

Objectives: The aim of this experimental study was to assess the possibility of decreasing the size of the ureteral stents used after an endopyelotomy. To this end, an experimental study was performed which compared a ureteral double-J wire stent versus a standard 7F ureteral stent after endopyelotomy. Methods: Twenty healthy female pigs were randomly divided into 2 groups: group I (double pigtail ureteral stent 7F) and group II (lumenless ureteral double-J wire stent, Zebrastent™, 0.035 inches in diameter). Percutaneous, endoluminal ultrasonographic and fluoroscopic studies were analyzed during the 3 different phases of the study. The first phase included premodel documentation of normal urinary tracts and laparoscopic ureteropelvic junction (UPJ) obstruction induction. During the second phase, 6 weeks later, diagnosis and endopyelotomy were carried out. Sixteen weeks after the obstruction treatment, follow-up imaging studies and postmortem evaluations of all animals were performed. Results: After the sonographic and fluoroscopic assessments, we determined the success rate for each group: 80% for group I and 90% for group II. No significant statistical differences were evident in the evolution of the diameter of the UPJ between groups. Better healing of the UPJ and a lower level of retroperitoneal repercussions were seen in group II. Conclusions:The ureteral double-J wire stent (Zebrastent) has been shown to be highly effective after endopyelotomy. This means that it is possible to reduce the size of ureteral stents after endopyelotomy with the advantages that this entails. Double-J ureteral stents probably act as a scaffold rather than a mold.