bluuebunny/crossref_metadata_2025_split huggingface dataset:
Asymptotic Convergence of Backpropagation
Authors: Tesauro Gerald , He Yu , Ahmad Subutai 
Published: March 2008

We calculate analytically the rate of convergence at long times in the backpropagation learning algorithm for networks with and without hidden units. For networks without hidden units using the standard quadratic error function and a sigmoidal transfer function, we find that the error decreases as 1/t for large t, and the output states approach their target values as 1/√t. It is possible to obtain a different convergence rate for certain error and transfer functions, but the convergence can never be faster than 1/t. These results are unaffected by a momentum term in the learning algorithm, but convergence can be substantially improved by an adaptive learning rate scheme. For networks with hidden units, we generally expect the same rate of convergence to be obtained as in the single-layer case; however, under certain circumstances one can obtain a polynomial speed-up for non sigmoidal units, or a logarithmic speed-up for sigmoidal units. Our analytic results are confirmed by empirical measurements of the convergence rate in numerical simulations.
How to Generate Ordered Maps by Maximizing the Mutual Information between Input and Output Signals
Authors: Linsker Ralph 
Published: March 2008

A learning rule that performs gradient ascent in the average mutual information between input and an output signal is derived for a system having feedforward and lateral interactions. Several processes emerge as components of this learning rule: Hebb-like modification, and cooperation and competition among processing nodes. Topographic map formation is demonstrated using the learning rule. An analytic expression relating the average mutual information to the response properties of nodes and their geometric arrangement is derived in certain cases. This yields a relation between the local map magnification factor and the probability distribution in the input space. The results provide new links between unsupervised learning and information-theoretic optimization in a system whose properties are biologically motivated.
Stimulus-Dependent Assembly Formation of Oscillatory Responses: I. Synchronization
Authors: König Peter , Schillen Thomas B. 
Published: March 2008

Current concepts in neurobiology of vision assume that local object features are represented by distributed neuronal populations in the brain. Such representations can lead to ambiguities if several distinct objects are simultaneously present in the visual field. Temporal characteristics of the neuronal activity have been proposed as a possible solution to this problem and have been found in various cortical areas. In this paper we introduce a delayed nonlinear oscillator to investigate temporal coding in neuronal networks. We show synchronization within two-dimensional layers consisting of oscillatory elements coupled by excitatory delay connections. The observed correlation length is large compared to coupling length. Following the experimental situation, we then demonstrate the response of such layers to two short stimulus bars of varying gap distance. Coherency of stimuli is reflected by the temporal correlation of the responses, which closely resembles the experimental observations.
Universal Approximation Using Radial-Basis-Function Networks
Authors: Park J. , Sandberg I. W. 
Published: March 2008

There have been several recent studies concerning feedforward networks and the problem of approximating arbitrary functionals of a finite number of real variables. Some of these studies deal with cases in which the hidden-layer nonlinearity is not a sigmoid. This was motivated by successful applications of feedforward networks with nonsigmoidal hidden-layer units. This paper reports on a related study of radial-basis-function (RBF) networks, and it is proved that RBF networks having one hidden layer are capable of universal approximation. Here the emphasis is on the case of typical RBF networks, and the results show that a certain class of RBF networks with the same smoothing factor in each kernel node is broad enough for universal approximation.
A Practical Approach for Representing Context and for Performing Word Sense Disambiguation Using Neural Networks
Authors: Gallant Stephen I. 
Published: March 2008

Representing and manipulating context information is one of the hardest problems in natural language processing. This paper proposes a method for representing some context information so that the correct meaning for a word in a sentence can be selected. The approach is primarily based on work by Waltz and Pollack (1985, 1984), who emphasized neutrally plausible systems. By contrast this paper focuses on computationally feasible methods applicable to full-scale natural language processing systems. There are two key elements: a collection of context vectors defined for every word used by a natural language processing system, and a context algorithm that computes a dynamic context vector at any position in a body of text. Once the dynamic context vector has been computed it is easy to choose among competing meanings for a word. This choice of definitions is essentially a neural network computation, and neural network learning algorithms should be able to improve such choices. Although context vectors do not represent all context information, their use should improve those full-scale systems that have avoided context as being too difficult to deal with. Good candidates for full-scale context vector implementations are machine translation systems and Japanese word processors. A main goal of this paper is to encourage such large-scale implementations and tests of context vector approaches. A variety of interesting directions for research in natural language processing and machine learning will be possible once a full set of context vectors has been created. In particular the development of more powerful context algorithms will be an important topic for future research.
An analysis of the clinical and biologic significance of TP53 loss and the identification of potential novel transcriptional targets of TP53 in multiple myeloma
Authors: Xiong Wei , Wu Xiaosong , Starnes Sarah , Johnson Sarah K. , Haessler Jeff , Wang Siqing , Chen Lijuan , Barlogie Bart , Shaughnessy John D. , Zhan Fenghuang 
Published: March 2008

AbstractTP53 is a tumor suppressor gene that functions as transcriptional regulator influencing cellular responses to DNA damage. Here we explored the clinical and transcriptional effects of TP53 expression in multiple myeloma (MM). We found that low expression of TP53, seen in approximately 10% of newly diagnosed patients, is highly correlated with TP53 deletion, an inferior clinical outcome, and represents an independent risk factor. Analysis of the expression of 122 known TP53 target genes in TP53-high vs -low MM cells from 351 newly diagnosed cases, revealed that only a few were highly correlated with TP53 expression. To elucidate TP53 regulatory networks in MM, we overexpressed TP53 in 4 MM cell lines. Gene expression profiling of these cell lines detected 85 significantly differentially expressed genes, with 50 up-regulated and 35 down-regulated. Unsupervised hierarchical clustering of myeloma samples from 351 newly diagnosed and 90 relapsed patients using the 85 putative TP53 target genes revealed 2 major subgroups showing a strong correlation with TP53 expression and survival. These data suggest that loss of TP53 expression in MM confers high risk and probably results in the deregulation of a novel set of MM-specific TP53-target genes. TP53 target gene specificity may be unique to different cell lineages.
Synergistic interactions between interferon-γ and TRAIL modulate c-FLIP in endothelial cells, mediating their lineage-specific sensitivity to thrombotic thrombocytopenic purpura plasma–associated apoptosis
Authors: Stefanescu Radu , Bassett Dustin , Modarresi Rozbeh , Santiago Francisco , Fakruddin Mohamad , Laurence Jeffrey 
Published: March 2008

Abstract
Microvascular endothelial cell (MVEC) injury coupled to progression of platelet microthrombi facilitated by ADAMTS13 deficiency is characteristic of idiopathic and HIV-linked thrombotic thrombocytopenic purpura (TTP). Cytokines capable of inducing MVEC apoptosis in vitro are up-regulated in both TTP and HIV infection. However, the concentrations of these cytokines required to elicit EC apoptosis in vitro are 2- to 3-log–fold greater than present in patient plasmas. We report that clinically relevant levels of tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) and interferon (IFN)–γ act in synergy to induce apoptosis in dermal MVECs, but have no effect on large-vessel ECs or pulmonary MVECs. This reflects the tissue distribution of TTP lesions in vivo. Sensitivity to TTP plasma or TRAIL plus IFN-γ is paralleled by enhanced ubiquitination of the caspase-8 regulator cellular FLICE-like inhibitory protein (c-FLIP), targeting it for proteasome degradation. c-FLIP silencing with anti-FLIP short interfering RNA (siRNA) in pulmonary MVECs rendered them susceptible to TTP plasma– and cytokine-mediated apoptosis, while up-regulation of c-FLIP by gene transfer partially protected dermal MVECs from such injury. TTP plasma–mediated apoptosis appears to involve cytokine-induced acceleration of c-FLIP degradation, sensitizing cells to TRAIL-mediated caspase-8 activation and cell death. Suppression of TRAIL or modulation of immunoproteasome activity may have therapeutic relevance in TTP.
Metabolic responses to pyruvate kinase deletion in lysine producing Corynebacterium glutamicum
Authors: Becker Judith , Klopprogge Corinna , Wittmann Christoph 
Published: March 2008

Abstract

Background
Pyruvate kinase is an important element in flux control of the intermediate metabolism. It catalyzes the irreversible conversion of phosphoenolpyruvate into pyruvate and is under allosteric control. In Corynebacterium glutamicum, this enzyme was regarded as promising target for improved production of lysine, one of the major amino acids in animal nutrition. In pyruvate kinase deficient strains the required equimolar ratio of the two lysine precursors oxaloacetate and pyruvate can be achieved through concerted action of the phosphotransferase system (PTS) and phosphoenolpyruvate carboxylase (PEPC), whereby a reduced amount of carbon may be lost as CO2 due to reduced flux into the tricarboxylic acid (TCA) cycle. In previous studies, deletion of pyruvate kinase in lysine-producing C. glutamicum, however, did not yield a clear picture and the exact metabolic consequences are not fully understood.

Results
In this work, deletion of the pyk gene, encoding pyruvate kinase, was carried out in the lysine-producing strain C. glutamicum lysCfbr, expressing a feedback resistant aspartokinase, to investigate the cellular response to deletion of this central glycolytic enzyme. Pyk deletion was achieved by allelic replacement, verified by PCR analysis and the lack of in vitro enzyme activity. The deletion mutant showed an overall growth behavior (specific growth rate, glucose uptake rate, biomass yield) which was very similar to that of the parent strain, but differed in slightly reduced lysine formation, increased formation of the overflow metabolites dihydroxyacetone and glycerol and in metabolic fluxes around the pyruvate node. The latter involved a flux shift from pyruvate carboxylase (PC) to PEPC, by which the cell maintained anaplerotic supply of the TCA cycle. This created a metabolic by-pass from PEP to pyruvate via malic enzyme demonstrating its contribution to metabolic flexibility of C. glutamicum on glucose.

Conclusion
The metabolic flux analysis performed illustrates the high flexibility of the metabolic network of C. glutamicum to compensate for external perturbation. The organism could almost maintain its growth and production performance through a local redirection of the metabolic flux, thereby fulfilling all anabolic and catabolic needs. The formation of the undesired overflow metabolites dihydroxyacetone and glycerol, in the deletion mutant, however, indicates a limiting capacity of the metabolism down-stream of their common precursor glyceraldehyde 3-phosphate and opens possibilities for further strain engineering.
Pseudosarcomatous myofibroblastic lesion of the urinary bladder: A rare entity posing a diagnostic challenge and therapeutic dilemma
Authors: Lekas Alexandros , Parasi Aikaterini , Papathomas Thomas G , Papatsoris Athanasios G , Mennonna Maria Rozaria , Chrisofos Michail , Deliveliotis Charalambos , Lazaris Andreas C 
Published: March 2008

Abstract

Background
Pseudosarcomatous myofibroblastic lesions of the urinary bladder are relatively rare entities of an uncertain pathogenesis and benign indolent nature.

Case presentation
We present an extremely rare case of an ALK-1-positive pseudosarcomatous myofibroblastic lesion of the urinary bladder, which was initially misinterpreted as a low-grade leiomyosarcoma of myxoid subtype on histologic examination owing to prominent atypia, high mitotic activity, abnormal mitotic figures and infiltration of the bladder wall. Although the histologic features were suggestive of a sarcoma, the correct diagnosis was finally established and radical surgical treatment was subsequently avoided. The patient is currently free of disease without any evidence of tumor recurrence or metastasis at 3 years post-operatively.

Conclusion
The key differentiating point rests in distinguishing the aforementioned mass forming lesion from the myxoid subtype of low-grade leiomyosarcoma in order to avoid unnecessary radical therapy.
Effect of Pretreatment Distress on Daily Fatigue After Chemotherapy for Breast Cancer
Authors: Higgins Sara C. , Montgomery Guy H. , Raptis George , Bovbjerg Dana H. 
Published: March 2008

Purpose Fatigue is one of the most frequently reported and adverse effects of cancer chemotherapy. The present study tested the hypothesis that women's levels of emotional distress at the time of their initial outpatient chemotherapy treatment would predict the severity of their postinfusion fatigue. Methods Sixty stage I (32.6%) and II (67.4%) patients with breast cancer (mean age, 44.5 years) who were receiving standard outpatient chemotherapy participated. The independent variable, emotional distress, was assessed for “last night,” “this morning,” and “right now” with a visual analog scale (0 to 100). The dependent variable, post-treatment fatigue (PTF), was assessed (0 to 100) over each of the subsequent 6 days using end-of-day diaries, which also included assessments of distress and nausea (0 to 100). For the statistical analyses, post-treatment fatigue was divided into three phases with means calculated for days 1 through 2 (phase 1), 3 to 4 (phase 2), and 5 to 6 (phase 3). Results Consistent with the study hypothesis, patients' pretreatment distress level in the clinic was a significant (P < .001) predictor of PTF. There was also a significant (P < .025) interaction with phase, with distress becoming a predictor of PTF after phase 1. Multivariate analysis indicated that prior levels of distress were not independent predictors of PTF. Conclusions This study is the first to demonstrate time-specific effects of pretreatment distress on PTF. Possible mechanisms of these effects now warrant investigation, as do possible benefits of brief interventions to reduce patient distress immediately before treatment.
A comparison between conventional recuperative gas turbine and hybrid solid oxide fuel cell—gas turbine systems with direct/indirect integration
Authors: Sánchez D , Chacartegui R , Sánchez T , Martínez J , Rosa F 
Published: March 2008

Conventional recuperative micro gas turbines have a 30 per cent low heating value (LHV) maximum efficiency at full load. Therefore, if they are to be used in a potential distributed energy scenario, solutions must be developed that increase efficiency. An innovative gas turbine-based technology is the fuel cell — gas turbine hybrid system. This work is aimed at studying how the basic performance of a conventional Brayton cycle changes when heat addition is done at a fuel cell. Two layouts are considered: a direct system where the compressor feeds the fuel cell directly and an indirect system where only heat is transferred between subsystems. Direct and indirect systems have been studied at full and part load, concluding that the efficiency versus pressure ratio curves of hybrid systems change substantially with respect to a traditional gas turbine; part-load efficiency hardly decreases. Maximum efficiency of hybrid systems doubles the efficiency of state of the art micro gas turbine and remains high at part load. Furthermore, the benefit of a certain increase in temperature is higher for hybrid systems than for conventional engines. Finally, a simple economic analysis shows that the total installation and operation/maintenance costs of hybrid systems make them competitive against conventional gas turbines.
Designing Pricing Contracts for Boundedly Rational Customers: Does the Framing of the Fixed Fee Matter?
Authors: Ho Teck-Hua , Zhang Juanjuan 
Published: March 2008

The format of pricing contracts varies substantially across business contexts, a major variable being whether a contract imposes a fixed fee payment. This paper examines how the use of the fixed fee in pricing contracts affects market outcomes of a manufacturer-retailer channel. Standard economic theories predict that channel efficiency increases with the introduction of the fixed fee and is invariant to its framing. We conduct a laboratory experiment to test these predictions. Surprisingly, the introduction of the fixed fee fails to increase channel efficiency. Moreover, the framing of the fixed fee does make a difference: an opaque frame as quantity discounts achieves higher channel efficiency than a salient frame as a two-part tariff, although these two contractual formats are theoretically equivalent.To account for these anomalies, we generalize the standard economic model by allowing the retailer's utilities to be reference dependent so that the up-front fixed fee payment is perceived as a loss and the subsequent retail profits as a gain. We embed this reference-dependent utility function in a quantal response equilibrium framework where the retailer is allowed to make decision mistakes due to computational complexity. The key prediction of this behavioral model is that channel efficiency decreases with loss aversion for sufficiently Nash-rational retailers. Consistent with this prediction, the estimated loss-aversion coefficient is 1.37 in the two-part tariff condition, significantly higher than 1.27 in the quantity discount condition. At the same time, loss aversion dominates contract complexity in explaining the data. Lastly, we conduct a follow-up experiment to confirm the central role of loss aversion as a behavioral driver. In one condition, the retailer becomes less loss averse when we temporally compress the fixed fee payment and the realization of retail profits, which supports the loss aversion theory. In the other condition, the retailer's contract acceptance rate does not decline when we reward the manufacturer a higher cash payment for each experimental point earned, which rules out the competing hypothesis that the retailer rejects contract offers due to fairness concerns.
Evaluation of Recovery Goals for Endangered White Sturgeon in the Kootenai River, Idaho
Authors: Paragamian Vaughn L. , Hansen Michael J. 
Published: March 2008

Abstract
Our objective was to evaluate recovery goals for endangered white sturgeon Acipencer transmontanus in the Kootenai River, Idaho. We used demographic statistics for white sturgeon in the Kootenai River in a stochastic density-dependent population model to estimate recruitment rates needed for population recovery. We simulated future abundance of white sturgeon in the Kootenai River over a 25-year period and a range of hypothetical recruitment rates to estimate the level of recruitment that would lead to population recovery (7,000 fish, the number present before the population suffered recruitment failure). We compared simulations of future abundance at enhanced levels of recruitment with those based on the present status of the population and with the recruitment criterion in the Kootenai River White Sturgeon Recovery Plan. We found that the population would decline to only 57 individuals after 25 years and only 6 individuals after 50 years if recruitment failure continued. The population would reach the target carrying capacity of 7,000 individuals within 25 years only when each adult produced 0.4 age-1 recruits, a recruitment rate equivalent to reaching the target level of recruitment in the recovery plan every year. In contrast, the population would grow to only 1,200 individuals if the target level of recruitment in the recovery plan was produced in only 3 of every 10 years, as specified in the recovery plan. We suggest that recovery goals for white sturgeon in the Kootenai River can be modified as follows: (1) a population goal of 7,000 subadults and adults; (2) population recovery within 25 years; and (3) a minimum recruitment rate of at least 20 age-1 juveniles detected from each year-class in each of 10 years by use of a standardized monitoring protocol.
Measuring the Performance of Two Stationary Interrogation Systems for Detecting Downstream and Upstream Movement of PIT-Tagged Salmonids
Authors: Connolly Patrick J. , Jezorek Ian G. , Martens Kyle D. , Prentice Earl F. 
Published: March 2008

Abstract
We tested the performance of two stationary interrogation systems designed for detecting the movement of fish with passive integrated transponder (PIT) tags. These systems allowed us to determine the direction of fish movement with high detection efficiency and high precision in a dynamic stream environment. We describe an indirect method for deriving an estimate for detection efficiency and the associated variance that does not rely on a known number of fish passing the system. By using six antennas arranged in a longitudinal series of three arrays, we attained detection efficiencies for downstream- and upstream-moving fish exceeding 96% during high-flow periods and approached 100% during low-flow periods for the two interrogation systems we tested. Because these systems did not rely on structural components, such as bridges or culverts, they were readily adaptable to remote, natural stream sites. Because of built-in redundancy, these systems were able to perform even with a loss of one or more antennas owing to dislodgement or electrical failure. However, the reduction in redundancy resulted in decreased efficiency and precision and the potential loss of ability to determine the direction of fish movement. What we learned about these systems should be applicable to a wide variety of other antenna configurations and to other types of PIT tags and transceivers.