bluuebunny/crossref_metadata_2025 huggingface dataset:
Plasticity-Induced Symmetry Relationships Between Adjacent Self-Organizing Topographic Maps
Authors: Sylvester Jared , Reggia James
Published: September 2009

In many species, adjacent topographic maps in sensory neocortex are found to be oriented as roughly mirror-image copies of one another. Here we use a computational model to show for the first time that, in principle, adjacent cortical topographic maps that are mirror-image symmetric along two dimensions can arise from activity-dependent changes if the distribution radius of afferents sufficiently exceeds that of horizontal intracortical interactions. We also find that infrequently, other types of intermap symmetry and previously unexpected map relationships (such as interlocking rotation, in which two adjacent maps become intertwined) can occur. These results support the hypothesis that activity-dependent synaptic changes play a more important role in forming the orientations of adjacent cortical maps than is currently recognized.
Discrete States of Synaptic Strength in a Stochastic Model of Spike-Timing-Dependent Plasticity
Authors: Elliott Terry
Published: September 2009

A stochastic model of spike-timing-dependent plasticity (STDP) postulates that single synapses presented with a single spike pair exhibit all-or-none quantal jumps in synaptic strength. The amplitudes of the jumps are independent of spiking timing, but their probabilities do depend on spiking timing. By making the amplitudes of both upward and downward transitions equal, synapses then occupy only a discrete set of states of synaptic strength. We explore the impact of a finite, discrete set of strength states on our model, finding three principal results. First, a finite set of strength states limits the capacity of a single synapse to express the standard, exponential STDP curve. We derive the expression for the expected change in synaptic strength in response to a standard, experimental spike pair protocol, finding a deviation from exponential behavior. We fit our prediction to recent data from single dendritic spine heads, finding results that are somewhat better than exponential fits. Second, we show that the fixed-point dynamics of our model regulate the upward and downward transition probabilities so that these are on average equal, leading to a uniform distribution of synaptic strength states. However, third, under long-term potentiation (LTP) and long-term depression (LTD) protocols, these probabilities are unequal, skewing the distribution away from uniformity. If the number of states of strength is at least of order 10, then we find that three effective states of synaptic strength appear, consistent with some experimental data on ternary-strength synapses. On this view, LTP and LTD protocols may therefore be saturating protocols.
Current Source Density Reconstruction from Incomplete Data
Authors: Wójcik Daniel K. , Łęski Szymon
Published: September 2009

We propose two ways of estimating current source density (CSD) from measurements of voltage on a Cartesian grid with missing recording points using the inverse CSD method. The simplest approach is to substitute local averages (LA) in place of missing data. A more elaborate alternative is to estimate a smaller number of CSD parameters than the actual number of recordings and to take the least-squares fit (LS). We compare the two approaches in the three-dimensional case on several sets of surrogate and experimental data, for varying numbers of missing data points, and discuss their advantages and drawbacks. One can construct CSD distributions for which one or the other approach is better. However, in general, the LA method is to be recommended as being more stable and more robust to variations in the recorded fields.
Asymptotic Behavior of Periodic Cohen-Grossberg Neural Networks with Delays
Authors: Lin Wei
Published: September 2009

Without assuming the positivity of the amplification functions, we prove some M-matrix criteria for the [Formula: see text]-global asymptotic stability of periodic Cohen-Grossberg neural networks with delays. By an extension of the Lyapunov method, we are able to include neural systems with multiple nonnegative periodic solutions and nonexponential convergence rate in our model and also include the Lotka-Volterra system, an important prototype of competitive neural networks, as a special case. The stability criteria for autonomous systems then follow as a corollary. Two numerical examples are provided to show that the limiting equilibrium or periodic solution need not be positive.
Decoding Movement Trajectories Through a T-Maze Using Point Process Filters Applied to Place Field Data from Rat Hippocampal Region CA1
Authors: Huang Yifei , Brandon Mark P. , Griffin Amy L. , Hasselmo Michael E. , Eden Uri T.
Published: September 2009

Firing activity from neural ensembles in rat hippocampus has been previously used to determine an animal's position in an open environment and separately to predict future behavioral decisions. However, a unified statistical procedure to combine information about position and behavior in environments with complex topological features from ensemble hippocampal activity has yet to be described. Here we present a two-stage computational framework that uses point process filters to simultaneously estimate the animal's location and predict future behavior from ensemble neural spiking activity. First, in the encoding stage, we linearized a two-dimensional T-maze, and used spline-based generalized linear models to characterize the place-field structure of different neurons. All of these neurons displayed highly specific position-dependent firing, which frequently had several peaks at multiple locations along the maze. When the rat was at the stem of the T-maze, the firing activity of several of these neurons also varied significantly as a function of the direction it would turn at the decision point, as detected by ANOVA. Second, in the decoding stage, we developed a state-space model for the animal's movement along a T-maze and used point process filters to accurately reconstruct both the location of the animal and the probability of the next decision. The filter yielded exact full posterior densities that were highly nongaussian and often multimodal. Our computational framework provides a reliable approach for characterizing and extracting information from ensembles of neurons with spatially specific context or task-dependent firing activity.
Adaptive Relevance Matrices in Learning Vector Quantization
Authors: Schneider Petra , Biehl Michael , Hammer Barbara
Published: September 2009

We propose a new matrix learning scheme to extend relevance learning vector quantization (RLVQ), an efficient prototype-based classification algorithm, toward a general adaptive metric. By introducing a full matrix of relevance factors in the distance measure, correlations between different features and their importance for the classification scheme can be taken into account and automated, and general metric adaptation takes place during training. In comparison to the weighted Euclidean metric used in RLVQ and its variations, a full matrix is more powerful to represent the internal structure of the data appropriately. Large margin generalization bounds can be transferred to this case, leading to bounds that are independent of the input dimensionality. This also holds for local metrics attached to each prototype, which corresponds to piecewise quadratic decision boundaries. The algorithm is tested in comparison to alternative learning vector quantization schemes using an artificial data set, a benchmark multiclass problem from the UCI repository, and a problem from bioinformatics, the recognition of splice sites for C. elegans.
Hebbian Self-Organizing Integrate-and-Fire Networks for Data Clustering
Authors: Landis Florian , Ott Thomas , Stoop Ruedi
Published: September 2009

We propose a Hebbian learning-based data clustering algorithm using spiking neurons. The algorithm is capable of distinguishing between clusters and noisy background data and finds an arbitrary number of clusters of arbitrary shape. These properties render the approach particularly useful for visual scene segmentation into arbitrarily shaped homogeneous regions. We present several application examples, and in order to highlight the advantages and the weaknesses of our method, we systematically compare the results with those from standard methods such as the k-means and Ward's linkage clustering. The analysis demonstrates that not only the clustering ability of the proposed algorithm is more powerful than those of the two concurrent methods, the time complexity of the method is also more modest than that of its generally used strongest competitor.
Learning to Discriminate Through Long-Term Changes of Dynamical Synaptic Transmission
Authors: Leibold Christian , Bendels Michael H. K.
Published: September 2009

Short-term synaptic plasticity is modulated by long-term synaptic changes. There is, however, no general agreement on the computational role of this interaction. Here, we derive a learning rule for the release probability and the maximal synaptic conductance in a circuit model with combined recurrent and feedforward connections that allows learning to discriminate among natural inputs. Short-term synaptic plasticity thereby provides a nonlinear expansion of the input space of a linear classifier, whereas the random recurrent network serves to decorrelate the expanded input space. Computer simulations reveal that the twofold increase in the number of input dimensions through short-term synaptic plasticity improves the performance of a standard perceptron up to 100%. The distributions of release probabilities and maximal synaptic conductances at the capacity limit strongly depend on the balance between excitation and inhibition. The model also suggests a new computational interpretation of spikes evoked by stimuli outside the classical receptive field. These neuronal activities may reflect decorrelation of the expanded stimulus space by intracortical synaptic connections.
Productivity in Lesbian, Gay, Bisexual, and Transgender Scholarship in Counseling Psychology: Institutional and Individual Ratings for 1990 Through 2008
Authors: Smith Nathan Grant
Published: September 2009

This study examined individual and institutional productivity in lesbian, gay, bisexual, and transgender (LGBT) scholarship published in counseling psychology—oriented journals for the years 1990 through 2008. Eight journals were included in the analyses. An author-weighted score was calculated for each scholar, using a formula developed by Howard, Cole, and Maxwell. To determine the impact of authors’ work, h indices were calculated for the most productive scholars. Finally, institutions publishing LGBT scholarship were proportionally ranked, consistent with the work of Tinsley and Tinsley. Twenty-nine authors and 13 institutions emerged as leaders in LGBT scholarship. Data on percentage of articles published in each journal, as well as trends over time, are presented. Implications and directions for future research are discussed.
Dissociative Disorders in a Psychiatric Institute in India - A Selected Review and Patterns Over a Decade
Authors: Chaturvedi Santosh K. , Desai Geetha , Shaligram Deepika
Published: September 2009

Background: The prevalence — and type — of dissociative disorders is considered to vary across cultures and over time.

Aims: The aim of the study was to examine patterns of dissociative disorders among subjects attending psychiatric services over a period of 10 years.

Methods: The sample consisted of both inpatients and outpatients attending a psychiatric hospital between 1999 and 2008. Information of those subjects diagnosed to have dissociative disorders was reviewed. A semi-structured proforma was used to collect information about demographic details and diagnosis.

Results: A total of 893 patients had been diagnosed with dissociative disorder over the past decade: 591 (66%) were outpatients and 302 (34%) were inpatients. The proportion of patients diagnosed with dissociative disorders ranged between 1.5 and 15.0 per 1,000 for outpatients and between 1.5 and 11.6 per 1,000 for inpatients. The majority of patients were diagnosed with dissociative motor disorder (43.3% outpatients, 37.7% inpatients), followed by dissociative convulsions (23% outpatients, 27.8% inpatients). Female preponderance was seen across all sub-types of dissociative disorder except dissociative fugue.

Conclusions: Dissociative disorders are still commonly diagnosed in both inpatient and outpatient settings. Dissociative motor disorders and dissociative convulsions are the most common disorders. Unlike in the West, dissociative identity disorders were rarely diagnosed; instead, possession states were commonly seen in the Indian population, indicating cross-cultural disparity.
Angiogenic Signaling Triggered by Cariogenic Bacteria in Pulp Cells
Authors: Soden R.I. , Botero T.M. , Hanks C.T. , Nör J.E.
Published: September 2009

The inflammation observed in the dental pulp of teeth with deep caries lesions is characterized by a significant increase in blood vessel density. It is known that lipoteichoic acid (LTA) from Gram-positive cariogenic bacteria induces expression of vascular endothelial growth factor (VEGF) in dental pulp cells. The hypothesis underlying this study was that LTA induces VEGF expression in dental pulp cells through TLR2 and PI3k/Akt signaling. Odontoblast-like cells (MDPC-23) and undifferentiated pulp cells (OD-21) were exposed to LTA from Streptococcus sanguis, and the role of TLR2, PI3K/Akt, and IKK signaling in LTA-induced VEGF expression was evaluated. These studies demonstrated that TLR2 signaling through the PI3K-Akt pathway is necessary for LTA-induced VEGF expression in pulp cells. In contrast, inhibition of IKK signaling did not prevent VEGF up-regulation in response to LTA. Understanding signaling pathways triggered by cariogenic bacteria may reveal novel therapeutic targets for the clinical management of pulpitis.
Acceleration of Purine Degradation by Periodontal Diseases
Authors: Barnes V.M , Teles R. , Trivedi H.M. , Devizio W. , Xu T. , Mitchell M.W. , Milburn M.V. , Guo L.
Published: September 2009

Periodontal diseases, such as gingivitis and periodontitis, are characterized by bacterial plaque accumulation around the gingival crevice and the subsequent inflammation and destruction of host tissues. To test the hypothesis that cellular metabolism is altered as a result of host-bacteria interaction, we performed an unbiased metabolomic profiling of gingival crevicular fluid (GCF) collected from healthy, gingivitis, and periodontitis sites in humans, by liquid and gas chromatography mass spectrometry. The purine degradation pathway, a major biochemical source for reactive oxygen species (ROS) production, was significantly accelerated at the disease sites. This suggests that periodontal-disease-induced oxidative stress and inflammation are mediated through this pathway. The complex host-bacterial interaction was further highlighted by depletion of anti-oxidants, degradation of host cellular components, and accumulation of bacterial products in GCF. These findings provide new mechanistic insights and a panel of comprehensive biomarkers for periodontal disease progression.
Stability of the JP2 Clone of Aggregatibacter actinomycetemcomitans
Authors: Haubek D. , Ennibi O.-K. , Væth M. , Poulsen S. , Poulsen K.
Published: September 2009

The JP2 clone of Aggregatibacter actinomycetemcomitans is strongly associated with aggressive periodontitis. To obtain information about colonization dynamics of the JP2 clone, we used PCR to examine its presence in 365 Moroccan juveniles from whom periodontal plaque samples were collected at baseline and after one and two years. Periodontal attachment loss was measured at baseline and at the two-year follow-up. At baseline, 43 (12%) carriers of the JP2 clone were found. Nearly half (44 %) of these were persistently colonized with the clone. The relative risk for the development of aggressive periodontitis, adjusted for the concomitant presence of other genotypes of A. actinomycetemcomitans, was highest for individuals continuously infected by the JP2 clone (RR = 13.9; 95% CI, 9.0 to 21.4), indicating a relationship between infectious dose and disease, which further substantiates the evidence for the JP2 clone as a causal factor in aggressive periodontitis.
Poisson Analysis of Streptococcal Bond-strengthening on Saliva-coated Enamel
Authors: Mei L. , Ren Y. , Busscher H.J. , Chen Y. , van der Mei H.C.
Published: September 2009

The forces responsible for bond-strengthening in initial oral bacterial adhesion are unknown. Since Lifshitz-Van der Waals and electrostatic forces work instantaneously upon approach, it is hypothesized that bond-strengthening is governed by hydrogen bonding. Poisson analysis of adhesion forces observed during the retraction of bacterial probes from surfaces in atomic force microscopy can be used to analyze the nature of the adhesion forces. Streptococcal adhesion forces increased from about −0.7 to −10.3 nN when the contact time between cell surfaces and salivary films on enamel was increased from 0 to 120 sec. Initial and final adhesion forces were stronger for initial colonizers of tooth surfaces ( S. mitis, S. sanguinis) than for later, more cariogenic, strains ( S. sobrinus, S. mutans). Retraction curves after increased contact times showed minor peaks, representative of hydrogen bonds, and Poisson analyses indicated repulsive non-specific forces of around +0.3 nN and slightly more attractive hydrogen-bonding forces (−1.0 nN) for initial than for late colonizers (−0.8 nN).
Mechanical Properties of Tannic-acid-treated Dentin Matrix
Authors: Bedran-Russo A.K.B. , Yoo K.J. , Ema K.C. , Pashley D.H.
Published: September 2009

Dentin collagen is a major component of the hybrid layer, and its stability may have a great impact on the properties of adhesive interfaces. We tested the hypothesis that the use of tannic acid (TA), a collagen cross-linking agent, may affect the mechanical properties and stability of the dentin matrix. The present study evaluated the effects of different concentrations of TA on the modulus of elasticity and enzymatic degradation of dentin matrix. Hence, the effect of TA pre-treatment on resin-dentin bond strength was assessed with the use of two bonding systems. Sound human molars were used and prepared according to each experimental design. The use of TA affected the properties of demineralized dentin by increasing its stiffness. TA treatment inhibited the effect of collagenase digestion on dentin matrix, particularly for 10%TA and 20%TA. The TA-dentin matrix complex resulted in improved bond strength for both adhesive systems.
An Advanced System for Supporting the Decision Process within Large-scale Retail Stores
Authors: Bruzzone Agostino G. , Longo Francesco
Published: September 2009

This paper proposes an advanced decision system, called Virtual Dynamic Store (VDS), for supporting retail store management. The VDS architecture supports the decision processes within retail stores by providing users with three main functionalities: store layout analysis, item and shelf management, and store monitoring and control by real-time simulation (or remote control by on-line simulation). As additional functionality, not related to the decision process within a retail store, the VDS architecture could also be used as a virtual web shop for e-commerce. To provide evidence on the relevance of the VDS, the architecture is tested within a real store by proposing four different application examples that show the potential of the VDS as an advanced decision support system.
Do Women Feel Worse to Look Their Best? Testing the Relationship Between Self-Esteem and Fertility Status Across the Menstrual Cycle
Authors: Hill Sarah E. , Durante Kristina M.
Published: September 2009

Two studies measured self-esteem across the menstrual cycle to test the prediction that self-esteem will vary interindividually as a positive function of mate value and intraindividually as a negative function of fertility status. Study 1 (n = 52) found that self-esteem was positively related to mate value between women but that women experienced a self-esteem decrease nearest to ovulation, when women tend to be more attractive to men. Study 2 (n = 59) replicated these results and demonstrated that the self-esteem decrease at high fertility was positively related to women’s reported long-term mating motivation. Additionally, the magnitude of the self-esteem decrease at high fertility was found to be related to increased willingness to spend money on items to enhance attractiveness at high fertility. A self-esteem decrease at high fertility may motivate mate value enhancement efforts when such efforts are most critical.
Public Participation and Agency Discretion in Rulemaking at the Federal Communications Commission
Authors: Gangadharan Seeta Peña
Published: September 2009

In recent years, many practitioners, policymakers, and scholars have embraced participatory politics in communications policymaking at the Federal Communications Commission (FCC) with the expectation that mass involvement by the public will—and should—influence regulatory outcomes. However, calls for participation may not be sufficient; a commitment to public-spirited decision making among agency officials is also needed alongside procedural safeguards for participation. The following analysis uses a Habermasian framework to move beyond participatory politics and advocates for a deliberative understanding of the role of the public and policymakers in producing legitimate outcomes. Looking at legal and legislative history of the Commission and of administrative procedure more generally, the article reconsiders the value of agency discretion and turns attention to the importance of public participation in debates about communications regulation outside the rulemaking system. If members of the public generate, circulate, and make audible their opinions in a public sphere and agency officials are open to and active listeners of a public sphere, agency discretion can guide officials towards public-spirited rather than narrowly interested decisions. Overall, Habermas's model suggests that policymakers and public coproduce legitimacy in a process that is doubly challenging but arguably more profound.
Governance in changing times: the experiences of hospice trustees in the United Kingdom
Authors: Turner Mary , Payne Sheila
Published: September 2009

Hospice trustees are volunteers who are vital to the governance and management of independent, charitable hospices, yet little is known about their roles and concerns. This paper presents some findings from a qualitative study which explored the views and perspectives of hospice trustees in the UK. Twenty hospice trustees took part in semi-structured telephone interviews, which were analysed using an iterative thematic approach. Nine themes emerged from the analysis, and were grouped into two major categories. One theme, ‘becoming a trustee’, is presented in this paper to illustrate trustees’ concerns about the challenges they face in adapting to change. The pace of change currently facing hospices in the UK is an issue of particular concern to trustees, presenting ongoing challenges for this group of volunteers. The study also raises wider questions about how hospices wish to position themselves in the future.
Bereavement needs assessment in specialist palliative care: a review of the literature
Authors: Agnew A. , Manktelow R. , Taylor BJ , Jones L.
Published: September 2009

Bereavement needs assessment for specialist palliative care services has been highlighted as important by NICE guidance on palliative care for adults with cancer. Identifying and implementing appropriate bereavement measurement tools has remained a challenge. This paper identifies and reviews bereavement measurement tools to determine their suitability for use within bereavement services and hospice settings. Cochrane, MEDLINE, PsycINFO and CINAHL, electronic databases were searched, yielding 486 papers. From fifty-nine full text papers appraised, 10 measurement tools were analysed in detail. Some tools had been tested on specific populations which limited transferability to specialist palliative care settings; some lacked adequate theoretical links and were not effective in discriminating between normal and complicated grief reactions; and some lacked clear evidence of validity or reliability. Based on these criteria, conclusions are drawn about the suitability of particular tools for UK bereavement services and hospice settings where intervention is delivered by both trained professionals and volunteers.
Cognitive Function and Event-Related Potentials in Children With Type 1 Diabetes Mellitus
Authors: Shehata Ghaydaa , Eltayeb Azza
Published: September 2009

Type 1 diabetes mellitus is associated with cognitive changes, but the extent of cognition decline depends on age at onset, duration of diabetes, and occurrence of attacks of hypoglycemia or ketoacidosis. This study was designed to assess cognitive function in a group of children with type 1 diabetes mellitus. A total of 40 diabetic children were recruited from the pediatric department of Assiut University Hospital, Egypt. Forty healthy children matched for age, sex, and socioeconomic status were chosen as controls for comparison. Cognition was assessed using Stanford—Binet and event-related potentials tests. Compared to the control group, patients reported a significant reduction in intelligent quotient, comprehension, abstract visual reasoning, quantitative reasoning, bead memory, and total short memory testing for cognitive functions. Prolonged N1, P200, N2, and P300 latencies and reduced P300-N2 amplitude were reported. Significant negative correlations were identified in most studied cognitive functions and ketoacidosis or family history of diabetes mellitus.
The Mediation of Policy Knowledge: An Interpretive Analysis of Intersecting Activity Systems
Authors: Canary Heather E. , McPhee Robert D.
Published: September 2009

We use structurating activity theory,an integration of structuration and cultural-historical activity theories, to examine how individuals construct policy knowledge.The study was conducted over 5 months with participants from related activity systems who interacted regarding special education policy. Qualitative analysis focused on how participants drew on system-specific and structural rules and resources to construct policy knowledge within and between activity systems. Results reveal how participants developed policy knowledge that was mediated by system elements of divisions of labor, communities, rules, subjects, and both material and symbolic mediating resources.The mediated knowledge construction process also reproduced broad structural features. Results interpreted through structurating activity theory extend current understandings of policy and knowledge processes and offer directions for future research.
Is it Possible to Eradicate Poverty without Attending to Mental Health? Listening to Migrant Workers in Chile through their Idioms of Distress
Authors: C. Lorena Núñez
Published: September 2009

Departing from the existing critique of the Millennium Development Goals (MDGs), regarding the absence of mental health dimensions in the formulation of its poverty related goal, this article explores the interrelation between poverty and mental health by examining experiences of emotional distress of Peruvian migrant workers in Chile. Through an analysis of the idioms that Peruvian migrants use to communicate their distress, this article proposes an understanding of Peruvian migrant's emotional suffering that attends to the broader unequal relations that migrant workers are subjected to in the host society. The analysis enables an understanding of their experiences of social exclusion and personal uprootedness, making visible the agency that the migrants display in giving meanings and coping with their emotional distress, most often outside the medical system. This article argues for the need to develop alternative and culturally sensitive approaches to mental health, in order to support the everyday struggles of the poor.
A Review of the Minnesota Multiphasic Personality Inventory—Adolescent (MMPI-A) and the Millon Adolescent Clinical Inventory (MACI) With an Emphasis on Juvenile Justice Samples
Authors: Baum Linda J. , Archer Robert P. , Forbey Johnathan D. , Handel Richard W.
Published: September 2009

The Minnesota Multiphasic Personality Inventory—Adolescent (MMPI-A) and Millon Adolescent Clinical Inventory (MACI) are frequently used objective personality self-report measures. Given their widespread use, the purpose of the current study was to examine and compare the literature base for the two instruments. A comprehensive review of the literature was conducted between the years 1992 and 2007 using the PsycINFO Database. Results indicate the publication of 277 articles, books, book chapters, monographs, and dissertation abstracts on the MMPI-A. This was compared with the results of a comparable search for the MACI, which yielded 84 citations. The literature was further explored by determining the content of the topic areas addressed for both instruments. A particular focus was placed on the utility of the instruments with juvenile justice populations; scale means, standard deviations, and effect sizes calculated from this literature were examined. Results indicate that the use of the MMPI-A is supported by a substantial literature and a growing research base is also available for the MACI. Both instruments appear to provide useful results in juvenile justice settings.
A Psychometric Examination of Multidimensional Inventory of Black Identity (MIBI) Scores
Authors: Vandiver Beverly J. , Worrell Frank C. , Delgado-Romero Edward A.
Published: September 2009

The factor structure of the Multidimensional Inventory of Black Identity (MIBI) was assessed in a sample of 272 African American college students using confirmatory and exploratory factor analyses. The fit indices from the confirmatory analyses did not support the seven-factor first-order model or two alternative higher-order models suggested by the developers, but yielded numerous recommendations for modifications. A post hoc exploratory factor analysis indicated that MIBI items were best represented by a five-factor structure.
Anticoagulation and Coagulation Management for ECMO
Authors: Oliver William C.
Published: September 2009

Advances in extracorporeal membrane oxygenation (ECMO) management have helped to reduce complications compared with its inception but they remain high. The principal causes of mortality and morbidity are bleeding and thrombosis. The nonbiologic surface of an extracorporeal circuit provokes a massive inflammatory response leading to consumption and activation of procoagulant and anticoagulant components. The vast differences in neonatal and adult anticoagulation and transfusion requirements demands tremendous clinical knowledge to provide the best care. Increased use of thrombelastogram will complement other methods currently being used to improved care. Methods to recognize the level of thrombin formation at the bedside could help reduce neurologic complications. ECMO requires a multidisciplinary team approach to achieve the best outcomes.
Resource Management
Authors: Maccabe Arthur , Falter Hugo , Kramer William
Published: September 2009

Application scalability is directly related to the ability of the application developer to effectively use the resources provided by a computing system. As we start to address the development of exascale platforms, we must engage in a dialog to define the terms related to resource management. Approaches to resource management can be categorized in two dimensions: static/dynamic and explicit/ implicit. The static/dynamic dimension refers to when resource management decisions are made: prior to program execution or during program execution. The implicit/ explicit dimension refers to the object that implements the decision making: the tools that implement the programming environment or the application developer. The development of applications that can scale to the resources provided by an exascale system will require tools that allow programmers to move easily and seamlessly between these dimensions as they express resource management decisions.
A Collaboration and Commercialization Model for Exascale Software Research
Authors: Seager Mark , Gorda Brent
Published: September 2009

We propose a coordinated strategy for exascale software development that includes the incorporation of successful research and development (R&D) into development and engineering (D&E) projects and harvesting the successful D&E projects into products with vendor support (P&S). This allows the most flexible R&D agenda while at the same time providing a commercialization path. This process is described as a natural extension of current focus areas and funding agents for R&D, D&E and P&S, but adds stake holders from the next stage in the process in the upstream processes. This model allows the flexibility to encourage development and competition of ideas in the research, development and productization phases. We anticipate that multiple iterations through this process from R&D through P&S are required to achieve appropriate software for Exascale systems.
Toward Exascale Resilience
Authors: Cappello Franck , Geist Al , Gropp Bill , Kale Laxmikant , Kramer Bill , Snir Marc
Published: September 2009

Over the past few years resilience has became a major issue for high-performance computing (HPC) systems, in particular in the perspective of large petascale systems and future exascale systems. These systems will typically gather from half a million to several millions of central processing unit (CPU) cores running up to a billion threads. From the current knowledge and observations of existing large systems, it is anticipated that exascale systems will experience various kind of faults many times per day. It is also anticipated that the current approach for resilience, which relies on automatic or application level checkpoint/ restart, will not work because the time for checkpointing and restarting will exceed the mean time to failure of a full system. This set of projections leaves the community of fault tolerance for HPC systems with a difficult challenge: finding new approaches, which are possibly radically disruptive, to run applications until their normal termination, despite the essentially unstable nature of exascale systems. Yet, the community has only five to six years to solve the problem. This white paper synthesizes the motivations, observations and research issues considered as determinant of several complimentary experts of HPC in applications, programming models, distributed systems and system management.
Working together — primary care doctors’ and nurses’ attitudes to collaboration
Authors: Hansson Anders , Arvemo Tobias , Marklund Bertil , Gedda Birgitta , Mattsson Bengt
Published: September 2009

Background: Multidisciplinary teamwork is recommended for various disorders and it has been suggested that it is a way to meet the new challenges and demands facing general practitioners (GPs) in modern society. Attempts to introduce the method in primary care have failed partly due to GPs’ unwillingness to participate. The aim of this study was to measure attitudes towards collaboration among GPs and district nurses (DN) and to investigate whether there is a correlation between a positive attitude toward collaboration and high self-esteem in the professional role. Methods: The Jefferson Scale of Attitudes toward Physician Nurse Collaboration and the Professional Self-Description Form (PSDF) was used to study a cohort of 600 GPs and DNs in Västra Götaland region. The purpose was to map differences and correlations of attitude between DNs and GPs, between male and female GPs, and between older and younger DNs and GPs. Results: Four hundred and one answers were received. DNs (mean 51.7) were significantly more positive about collaboration than GPs (mean 49.4). There was no difference between younger and older, male and female GPs. DNs scored higher on the PSDF-scale than GPs. Conclusions: DNs were slightly more positive about collaboration than GPs. A positive attitude towards collaboration did not seem to be a part of the GPs’ professional role to the same extent as it is for DNs. Professional norms seem to have more influence on attitudes than do gender roles. DNs seem more confident in their profession than GPs.
GM-CSF and IL-4 induce dendritic cell differentiation and disrupt osteoclastogenesis through M-CSF receptor shedding by up-regulation of TNF-α converting enzyme (TACE)
Authors: Hiasa Masahiro , Abe Masahiro , Nakano Ayako , Oda Asuka , Amou Hiroe , Kido Shinsuke , Takeuchi Kyoko , Kagawa Kumiko , Yata Kenichiro , Hashimoto Toshihiro , Ozaki Shuji , Asaoka Kenzo , Tanaka Eiji , Moriyama Keiji , Matsumoto Toshio
Published: September 2009

Monocytes give rise to macrophages, osteoclasts (OCs), and dendritic cells (DCs). Macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor-kappaB (RANK) ligand induce OC differentiation from monocytes, whereas granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4) trigger monocytic differentiation into DCs. However, regulatory mechanisms for the polarization of monocytic differentiation are still unclear. The present study was undertaken to clarify the mechanism of triggering the deflection of OC and DC differentiation from monocytes. GM-CSF and IL-4 abolished monocytic differentiation into OCs while inducing DC differentiation even in the presence of M-CSF and RANK ligand. GM-CSF and IL-4 in combination potently up-regulate tumor necrosis factor-α (TNF-α) converting enzyme (TACE) and activity in monocytes, causing ectodomain shedding of M-CSF receptor, resulting in the disruption of its phosphorylation by M-CSF as well as the induction of osteoclastogenesis from monocytes by M-CSF and RANK ligand. Interestingly, TACE inhibition robustly causes the resumption of the surface expression of M-CSF receptor on monocytes, facilitating M-CSF–mediated phosphorylation of M-CSF receptor and macrophage/OC differentiation while impairing GM-CSF– and IL-4–mediated DC differentiation from monocytes. These results reveal a novel proteolytic regulation of M-CSF receptor expression in monocytes to control M-CSF signaling and monocytic differentiation into macrophage/OC-lineage cells or DCs.
Generation of CD8+ T cell–mediated immunity against idiotype-negative lymphoma escapees
Authors: Varghese Bindu , Widman Adam , Do James , Taidi Behnaz , Czerwinski Debra K. , Timmerman John , Levy Shoshana , Levy Ronald
Published: September 2009

We investigated the ability of CpG-oligodeoxynucleotide to generate an anti-tumor CD8+ T-cell immune response and to synergize with passive antibody therapy. For these studies, we generated an antibody against the idiotype on the A20 B-cell lymphoma line. This antibody caused the regression of established tumors, but ultimately the tumors relapsed. The escaping surface IgG-negative tumor cells were resistant to both antibody-dependent cellular cytotoxicity and signaling-induced cell death. Addition of intratumoral CpG to antibody therapy cured large established tumors and prevented the occurrence of tumor escapees. The failure of the combination therapy in mice deficient for CD8+ T cells demonstrates the critical role of CD8+ T cells in tumor eradication. When mice were inoculated with 2 tumors and treated systemically with antibody followed by intratumoral CpG in just one tumor, both tumors regressed, indicating that a systemic immune response was generated. Although antibody therapy can eliminate tumor cells bearing the target antigen, it frequently selects for antigen loss variants. However, when a poly-specific T-cell response was generated against the tumor by intratumoral CpG, even large established tumors were cured. Such an immune response can prevent the emergence of antibody selected tumor escapees and provide long-lasting tumor protection.
CD56+ human blood dendritic cells effectively promote TH1-type γδ T-cell responses
Authors: Gruenbacher Georg , Gander Hubert , Rahm Andrea , Nussbaumer Walter , Romani Nikolaus , Thurnher Martin
Published: September 2009

CD56+ human dendritic cells (DCs) have recently been shown to differentiate from monocytes in response to GM-CSF and type 1 interferon in vitro. We show here that CD56+ cells freshly isolated from human peripheral blood contain a substantial subset of CD14+CD86+HLA-DR+ cells, which have the appearance of intermediate-sized lymphocytes but spontaneously differentiate into enlarged DC-like cells with substantially increased HLA-DR and CD86 expression or into fully mature CD83+ DCs in response to appropriate cytokines. Stimulation of CD56+ cells containing both DCs and abundant γδ T cells with zoledronate and interleukin-2 (IL-2) resulted in the rapid expansion of γδ T cells as well as in IFN-γ, TNF-α, and IL-1β but not in IL-4, IL-10, or IL-17 production. IFN-γ, TNF-α, and IL-1β production were almost completely abolished by depleting CD14+ cells from the CD56+ subset before stimulation. Likewise, depletion of CD14+ cells dramatically impaired γδ T-cell expansion. IFN-γ production could also be blocked by neutralizing the effects of endogenous IL-1β and TNF-α. Conversely, addition of recombinant IL-1β, TNF-α, or both further enhanced IFN-γ production and strongly up-regulated IL-6 production. Our data indicate that CD56+ DCs from human blood are capable of stimulating CD56+ γδ T cells, which may be harnessed for immunotherapy.
Ray-based stochastic inversion of prestack seismic data for improved reservoir characterization
Authors: van der Burg Dennis , Verdel Arie , Wapenaar Kees
Published: September 2009

Trace inversion for reservoir parameters is affected by angle averaging of seismic data and wavelet distortion on the migration image. In an alternative approach to stochastic trace inversion, the data are inverted prestack before migration using 3D dynamic ray tracing. This choice makes it possible to interweave trace inversion with Kirchhoff migration. The new method, called ray-based stochastic inversion, is a generalization of current amplitude versus offset/amplitude versus angle (AVO/AVA) inversion techniques. The new method outperforms standard stochastic inversion techniques in cases of reservoir parameter estimation in a structurally complex subsurface with substantial lateral velocity variations and significant reflector dips. A simplification of the method inverts the normal-incidence response from reservoirs with approximately planar layering at the subsurface target locations selected for inversion. It operates along raypaths perpendicular to the reflectors, the direction that offers optimal resolution to discern layering in a reservoir. In a test on field data from the Gulf of Mexico, reservoir parameter estimates obtained with the simplified method, the estimates found by conventional stochastic inversion, and the actual values at a well drilled after the inversion are compared. Although the new method uses only 2% of the prestack data, the result indicates it improves accuracy on the dipping part of the reservoir, where conventional stochastic inversion suffers from wavelet stretch caused by migration.
Feasibility of simplified integral equation modeling of low-frequency marine CSEM with a resistive target
Authors: Bakr Shaaban A. , Mannseth Trond
Published: September 2009

We have assessed the accuracy of a simplified integral equation (SIE) modeling approach for marine controlled-source electromagnetics (CSEM) with low applied frequencies and a resistive target. The most computationally intensive part of rigorous integral equation (IE) modeling is the computation of the anomalous electric field within the target itself. This leads to a matrix problem with a dense coefficient matrix. It is well known that, in general, the presence of many grid cells creates a computational disadvantage for dense-matrix methods compared to sparse-matrix methods. The SIE approach replaces the dense-matrix part of rigorous IE modeling by sparse-matrix calculations based on an approximation of Maxwell’s equations. The approximation is justified theoretically if a certain dimensionless parameter [Formula: see text] is small. As opposed to approximations of the Born type, the validity of the SIE approach does not rely on the anomalous field to be small in comparison with the background field in the target region. We have calculated [Formula: see text] for a range of parameter values typical for marine CSEM, and compared the SIE approach numerically to the rigorous IE method and to the quasi-linear (QL) and quasi-analytic (QA) approximate solutions. It is found that the SIE approach is very accurate for small [Formula: see text], corresponding to frequencies in the lower range of those typical for marine CSEM for petroleum exploration. In addition, the SIE approach is found to be significantly more accurate than the QL and QA approximations for small [Formula: see text].
The 1998 Valhall microseismic data set: An integrated study of relocated sources, seismic multiplets, and S-wave splitting
Authors: De Meersman K. , Kendall J.-M. , van der Baan M.
Published: September 2009

We relocate 303 microseismic events recorded in 1998 by sensors in a single borehole in the North Sea Valhall oil field. A semiautomated array analysis method repicks the P- and S-wave arrival times and P-wave polarizations, which are needed to locate these events. The relocated sources are confined predominantly to a [Formula: see text]-thick zone just above the reservoir, and location uncertainties are half those of previous efforts. Multiplet analysis identifies 40 multiplet groups, which include 208 of the 303 events. The largest group contains 24 events, and five groups contain 10 or more events. Within each multiplet group, we further improve arrival-time picking through crosscorrelation, which enhances the relative accuracy of the relocated events and reveals that more than 99% of the seismic activity lies spatially in three distinct clusters. The spatial distribution of events and wave-form similarities reveal two faultlike structures that match well with north-northwest–south-southeast-trending fault planes interpreted from 3D surface seismic data. Most waveform differences between multiplet groups located on these faults can be attributed to S-wave phase content and polarity or P-to-S amplitude ratio. The range in P-to-S amplitude ratios observed on the faults is explained best in terms of varying source mechanisms. We also find a correlation between multiplet groups and temporal variations in seismic anisotropy, as revealed by S-wave splitting analysis. We explain these findings in the context of a cyclic recharge and dissipation of cap-rock stresses in response to production-driven compaction of the underlying oil reservoir. The cyclic nature of this mechanism drives the short-term variations in seismic anisotropy and the reactivation of microseismic source mechanisms over time.