bluuebunny/crossref_metadata_2025 huggingface dataset:
Dual-Based Local Search for the Connected Facility Location and Related Problems
Authors: Bardossy M. Gisela , Raghavan S.
Published: March 2010

The connected facility location (ConFL) problem arises in a number of applications that relate to the design of telecommunication networks as well as data distribution and management problems on networks. It combines features of the uncapacitated facility location problem with the Steiner tree problem and is known to be NP-complete. In this setting, we wish to install a set of facilities on a communication network and assign customers to the installed facilities. In addition, the set of selected facilities needs to be connected by a Steiner tree. In this paper, we propose a dual-based local search heuristic that combines dual ascent and local search, which together yield strong lower and upper bounds to the optimal solution. Our procedure is applied to a slightly more general version of the ConFL problem that embraces a family of four different problems—the Steiner tree-star problem, the general Steiner tree-star problem, the ConFL problem, and the rent-or-buy problem—that combine facility location decisions with connectivity requirements. Consequently, our solution methodology successfully applies to all of them. We discuss a wide range of computational experiments that indicate that our heuristic is a very effective procedure that finds high-quality solutions very rapidly.
Reality Check: Combining Choice Experiments with Market Data to Estimate the Importance of Product Attributes
Authors: Feit Eleanor McDonnell , Beltramo Mark A. , Feinberg Fred M.
Published: March 2010

Discrete choice models estimated using hypothetical choices made in a survey setting (i.e., choice experiments) are widely used to estimate the importance of product attributes in order to make product design and marketing mix decisions. Choice experiments allow the researcher to estimate preferences for product features that do not yet exist in the market. However, parameters estimated from experimental data often show marked inconsistencies with those inferred from the market, reducing their usefulness in forecasting and decision making. We propose an approach for combining choice-based conjoint data with individual-level purchase data to produce estimates that are more consistent with the market. Unlike prior approaches for calibrating conjoint models so that they correctly predict aggregate market shares for a “baseline” market, the proposed approach is designed to produce parameters that are more consistent with those that can be inferred from individual-level market data.

The proposed method relies on a new general framework for combining two or more sources of individual-level choice data to estimate a hierarchical discrete choice model. Past approaches to combining choice data assume that the population mean for the parameters is the same across both data sets and require that data sets are sampled from the same population. In contrast, we incorporate in the model individual characteristic variables, and assert only that the mapping between individuals' characteristics and their preferences is the same across the data sets. This allows the model to be applied even if the sample of individuals observed in each data set is not representative of the population as a whole, so long as appropriate product-use variables are collected that can explain the systematic deviations between them. The framework also explicitly incorporates a model for the individual characteristics, which allows us to use Bayesian missing-data techniques to handle the situation where each data set contains different demographic variables. This makes the method useful in practice for a wide range of existing market and conjoint data sets. We apply the method to a set of conjoint and market data for minivan choice and find that the proposed method predicts holdout market choices better than a model estimated from conjoint data alone or a model that does not include demographic variables.
Dynamic Programming Models and Algorithms for the Mutual Fund Cash Balance Problem
Authors: Nascimento Juliana , Powell Warren
Published: March 2010

Fund managers have to decide the amount of a fund's assets that should be kept in cash, considering the trade-off between being able to meet shareholder redemptions and minimizing the opportunity cost from lost investment opportunities. In addition, they have to consider redemptions by individuals as well as institutional investors, the current performance of the stock market and interest rates, and the pattern of investments and redemptions that are correlated with market performance. We formulate the problem as a dynamic program, but this encounters the classic curse of dimensionality. To overcome this problem, we propose a provably convergent approximate dynamic programming algorithm. We also adapt the algorithm to an online environment, requiring no knowledge of the probability distributions for rates of return and interest rates. We use actual data for market performance and interest rates, and demonstrate the quality of the solution (compared to the optimal) for the top 10 mutual funds in each of nine fund categories. We show that our results closely match the optimal solution (in considerably less time), and outperform two static (newsvendor) models. The result is a simple policy that describes when money should be moved into and out of cash based on market performance.
Securitization and Real Investment in Incomplete Markets
Authors: Gaur Vishal , Seshadri Sridhar , Subrahmanyam Marti G.
Published: March 2010

We study the impact of financial innovations on real investment decisions within the framework of an incomplete market economy comprised of firms, investors, and an intermediary. The firms face unique investment opportunities that arise in their business operations and can be undertaken at given reservation prices. The cash flows thus generated are not spanned by the securities traded in the financial market and cannot be valued uniquely. The intermediary purchases claims against these cash flows, pools them together, and sells tranches of primary or secondary securities to the investors. We derive necessary and sufficient conditions under which projects are undertaken due to the intermediary's actions, and firms are amenable to the pool proposed by the intermediary, compared to the no-investment option or the option of forming alternative pools. We also determine the structure of the new securities created by the intermediary and identify how it exploits the arbitrage opportunities available in the market. Our results have implications for valuation of real investments, synergies among them, and their financing mechanisms. We illustrate these implications using an example of inventory decisions under random demand.

This paper was accepted by John Birge, focused issue editor.
Heterogeneous Vancomycin Resistance in Staphylococcus Aureus: A Review of Epidemiology, Diagnosis, and Clinical Significance
Authors: Rong Star L , Leonard Steven N
Published: March 2010

OBJECTIVE:

To provide an overview of heterogeneously glycopeptide intermediate Staphylococcus aureus, its epidemiology, methods of diagnosis, and clinical relevance.

DATA SOURCES:

Literature was retrieved in December 2009 through Academic Search Premier, Alt-Health Watch, MEDLINE, OVID, and PubMed, using the search terms heterogeneous glycopeptide-intermediate Staphylococcus aureus, hGISA, hVISA, vancomycin-intermediate Staphylococcus aureus, GISA, and VISA (from 2003 to December 2009). Additional references were obtained through review of publication citations.

STUDY SELECTION AND DATA EXTRACTION:

All articles retrieved through the literature search and reference review were evaluated for inclusion in this review.

DATA SYNTHESIS:

Heterogeneously glycopeptide-intermediate S. aureus (hGISA) has been shown to significantly complicate treatment for patients with bacteremia and often escapes detection in clinical laboratories. Population analysis profile area under the curve ratio (PAP-AUC) is considered to be the gold standard of hGISA detection; however, it is labor-intensive, expensive, and not feasible in a clinical setting. The Etest macromethod is a reasonable alternative to PAP, yielding high sensitivity and specificity, and has potential for routine use in clinical laboratories. Due to these difficulties in detection, an exact prevalence is difficult to obtain though, based on available data, it appears that approximately 5-15% of isolates display this phenotype. hGISA is associated with prolonged bacteremia, high bacterial load infections, prolonged antibiotic therapy, prolonged hospitalization, treatment failure, and potential for increased mortality.

CONCLUSIONS:

Overall, hGISA is associated with a poor clinical course in patients with bacteremia. Information is still lacking regarding the actual prevalence of hGISA as well as the extent of its clinical impact. A uniform method of diagnosis must be established in order to better account for all cases of hGISA. More studies must be conducted to assess clinical outcomes of hGISA.
Medication Risk must be Balanced with Benefit, not Fear
Authors: Jones Kelly W
Published: March 2010

The passionate topic in pharmacotherapy belongs to medication safety. A basic premise in medicine is to first do no harm: primum non nocere. But can this ancient principle hold true concerning medications? Medication alerts from the Food and Drug Administration (FDA) are being transmitted through emails daily. Recently, an FDA advisory committee reviewed acetaminophen and the risk of acute liver injury. They made recommendations that could change the patient utilization and market dynamics of acetaminophen. This article is a reminder that safety is always at risk when progress and benefit are the outcomes of pharmacotherapy. Risk and benefit are mutually inclusive ideas and should never be separated. When risk dominates, fear is generated.
State of the Art Review: Intravenous Fat Emulsions: Current Applications, Safety Profile, and Clinical Implications
Authors: Mirtallo Jay M , Dasta Joseph F , Kleinschmidt Kurt C , Varon Joseph
Published: March 2010

Objective

To review the current state of the science regarding intravenous fat emulsions (IVFEs), with an emphasis on their safety profile.

Data sources

Articles were identified via a search of the MEDLINE database, including publications from 1979 to December 2009, using a search string that included the terms parenteral nutrition, lipid emulsion, fat emulsion, IVFE, safety, adverse effect, neonate intralipid, and terms describing a range of specific adverse events (AEs) such as pancreatitis.

Study selection and data extraction

We selected articles that allowed us to compare the results of clinical trials involving delivery of medications via IVFEs with the historical use and effects of IVFEs in parenteral nutrition, with an emphasis on AEs. We focused on 2 drugs in current use that are administered intravenously in lipid emulsions: propofol and clevidipine.

Data synthesis

Clearance of the fat particles in IVFEs is mediated by the enzyme lipoprotein lipase. AEs are more likely if the rate or duration of IVFE administration exceeds the enzyme's clearance capacity. AEs are also more likely after administration of a 10% IVFE formulation than a 20% formulation, because the higher concentration of free phospholipid in the 10% formulation interferes with lipoprotein lipase activity. AEs can be reduced by administering IVFEs at a dosage ≤2.5 g/kg/day and at a rate ≤0.11 g/kg/h. The anesthetic agent propofol, which is formulated in a 10% IVFE, has been used clinically for 25 years. Typical AEs associated with propofol use include infection, high plasma triglyceride concentrations, and pancreatitis. Recent clinical trials involving clevidipine, which is formulated in a 20% IVFE, have demonstrated a low rate of lipid-related AEs.

Conclusions

The results of this review demonstrate that IVFEs are well tolerated when administered in accordance with guideline recommendations.
Article Commentary: Penny-Wise, Pound-Foolish? Highmark Medicare Services’ Proposal for Anticoagulation Clinic Reimbursement
Authors: Streiff Michael B , Kraus Peggy S , Pronovost Peter
Published: March 2010

Warfarin is prescribed to millions of Americans for the management of thromboembolism and is a common cause of adverse events. Optimizing warfarin therapy has been the focus of national quality improvement initiatives. Anticoagulation clinics have been demonstrated to result in better outcomes than usual care. Nevertheless, Highmark Medicare Services recently issued a provider bulletin on anticoagulation clinic visit reimbursement that we believe will adversely affect the care for patients on anticoagulation. In this commentary, we review the potential unintended consequences of this proposal and offer alternatives that we believe will increase the efficiency and quality of anticoagulation management.
Imatinib and Panax Ginseng: A Potential Interaction Resulting in Liver Toxicity
Authors: Bilgi Naveen , Bell Kim , Ananthakrishnan Ashwin N , Atallah Ehab
Published: March 2010

OBJECTIVE:

To report a case of imatinib-induced hepatotoxicity after concurrent ginseng ingestion in a patient with chronic myelogenous leukemia (CML).

CASE SUMMARY:

A 26-year-old man with CML who had taken imatinib 400 mg daily for 7 years with no complications presented with right upper quadrant pain. Laboratory test results included alanine aminotransferase 1069 U/L, aspartate aminotransferase 481 U/L, alkaline phosphatase 124 IU/L, total bilirubin 1.4 mg/dL, albumin 4.0 g/dL, and international normalized ratio 1.08. Liver biopsy showed acute lobular hepatitis favoring a drug-induced etiology, and a diagnosis of imatinib-induced hepatotoxicity was made. The patient's only lifestyle modification prior to the diagnosis of hepatotoxicity was daily ingestion of Panax ginseng via energy drinks for the past 3 months. Both imatinib and ginseng were discontinued, and the patient was treated with a short course of corticosteroids. Imatinib was later restarted at the same dose with no recurrent elevations in his liver enzyme levels.

DISCUSSION:

Imatinib-associated hepatotoxicity usually presents within 1-2 years of therapy initiation, with the median time to hepatotoxicity being 100 days. Ginseng is an herb that is not known to be hepatotoxic. In vivo, ginseng is known to inhibit CYP3A4, the primary enzyme involved in the metabolism of imatinib. We propose that our patient's late-onset imatinib-associated hepatotoxicity was due to an interaction between ginseng and imatinib through CYP3A4. Based on the Naranjo probability scale, it is probable that imatinib caused this patient's hepatotoxicity, and the Horn drug interaction probability scale also indicates a probable interaction between imatinib and ginseng.

CONCLUSIONS:

This case emphasizes the importance of continuous monitoring of liver function tests even after several years of imatinib therapy and the importance of advising patients to avoid ginseng and any other over-the-counter herbal supplements that may interact with imatinib.
Milgram's obedience to authority experiments: Origins and early evolution
Authors: Russell Nestar John Charles
Published: March 2010

Stanley Milgram's Obedience to Authority experiments remain one of the most inspired contributions in the field of social psychology. Although Milgram undertook more than 20 experimental variations, his most (in)famous result was the first official trial run – the remote condition and its 65% completion rate. Drawing on many unpublished documents from Milgram's personal archive at Yale University, this article traces the historical origins and early evolution of the obedience experiments. Part 1 presents the previous experiences that led to Milgram's conception of his rudimentary research idea and then details the role of his intuition in its refinement. Part 2 traces the conversion of Milgram's evolving idea into a reality, paying particular attention to his application of the exploratory method of discovery during several pilot studies. Both parts illuminate Milgram's ad hoc introduction of various manipulative techniques and subtle tension‐resolving refinements. The procedural adjustments continued until Milgram was confident that the first official experiment would produce a high completion rate, a result contrary to expectations of people's behaviour. Showing how Milgram conceived of, then arrived at, this first official result is important because the insights gained may help others to determine theoretically why so many participants completed this experiment.
The influence of role definition and affect in LMX: A process perspective on the personality – LMX relationship
Authors: Sears Greg J. , Hackett Rick D.
Published: March 2010

While leader–member exchange (LMX) theorists have argued that role definition and affective processes play a central role in LMX development, research has yet to examine their relative influence. Likewise, few studies have investigated how the personality of leader and follower play out in these processes. Drawing on a sample of 161 managers and their respective leaders, we develop and offer empirical support for a model in which leader and subordinate agreeableness and core self‐evaluations wield their respective influence through the affective and role definition processes underlying LMX. Implications of these findings for the theory and practice of LMX are discussed.
Valenzbindung oder Konstruktionsbindung? Eine Grundfrage der Grammatiktheorie
Authors: Jacobs Joachim
Published: March 2010

If signs of type X regularily cooccur with signs of type Y, this can be explained in two ways: (i) X is required by the valency of Y, or (ii) there is a complex construction Z that requires both X and Y. I argue that, when deciding between (i) and (ii), grammarians should consider, among other things, whether the cooccurence of X and Y resembles prototypical instances of (i). This recommendation is based on the fact that the properties of the prototype of (i) show that valency is a morphosyntactic feature of word forms (like plural). Therefore, if the cooccurence of X and Y does not resemble the prototype of (i), treating it as an instance of (i) would establish a wrong parallel to morphosyntactic phenomena. And, on the other hand, if it does resemble this prototype, treating it as an instance of (ii) would miss this parallel. – In the perspective of this proposal, I discuss some phenomena whose status between (i) and (ii) is controversial.
Encoding of Temporal Probabilities in the Human Brain
Authors: Bueti Domenica , Bahrami Bahador , Walsh Vincent , Rees Geraint
Published: March 2010

Anticipating the timing of future events is a necessary precursor to preparing actions and allocating resources to sensory processing. This requires elapsed time to be represented in the brain and used to predict the temporal probability of upcoming events. While neuropsychological, imaging, magnetic stimulation studies, and single-unit recordings implicate the role of higher parietal and motor-related areas in temporal estimation, the role of earlier, purely sensory structures remains more controversial. Here we demonstrate that the temporal probability of expected visual events is encoded not by a single area but by a wide network that importantly includes neuronal populations at the very earliest cortical stages of visual processing. Moreover, we show that activity in those areas changes dynamically in a manner that closely accords with temporal expectations.
Corticospinal Beta-Band Synchronization Entails Rhythmic Gain Modulation
Authors: van Elswijk Gijs , Maij Femke , Schoffelen Jan-Mathijs , Overeem Sebastiaan , Stegeman Dick F. , Fries Pascal
Published: March 2010

Rhythmic synchronization of neurons in the beta or gamma band occurs almost ubiquitously, and this synchronization has been linked to numerous nervous system functions. Many respective studies make the implicit assumption that neuronal synchronization affects neuronal interactions. Indeed, when neurons synchronize, their output spikes reach postsynaptic neurons together, trigger coincidence detection mechanisms, and therefore have an enhanced impact. There is ample experimental evidence demonstrating this consequence of neuronal synchronization, but beyond this, beta/gamma-band synchronization within a group of neurons might also modulate the impact of synaptic input to that synchronized group. This would constitute a separate mechanism through which synchronization affects neuronal interactions, but directin vivoevidence for this putative mechanism is lacking. Here, we demonstrate that synchronized beta-band activity of a neuronal group modulates the efficacy of synaptic input to that group in-phase with the beta rhythm. This response modulation was not an addition of rhythmic activity onto the average response but a rhythmic modulation of multiplicative input gain. Our results demonstrate that beta-rhythmic activity of a neuronal target group multiplexes input gain along the rhythm cycle. The actual gain of an input then depends on the precision and the phase of its rhythmic synchronization to this target, providing one mechanistic explanation for why synchronization modulates interactions.
Astrocyte-Produced Ephrins Inhibit Schwann Cell Migration via VAV2 Signaling
Authors: Afshari Fardad T. , Kwok Jessica C. , Fawcett James W.
Published: March 2010

Schwann cells are a promising candidate for bridging spinal cord injuries and remyelinating axons. However, grafted Schwann cells show little intermingling with host astrocytes and therefore limited migration from transplant sites. This leads to the formation of a sharp border between host astrocytes and Schwann cells, which results in axons stalling at the graft–host interface and failing to exit the graft. We investigated the possibility that Eph/ephrin interactions are involved in the segregation of Schwann cells and astrocytes and in limiting Schwann cell migration. Using reverse transcription-PCR, we have characterized the ephrin and Eph profile in cultured Schwann cells and astrocytes, showing that astrocytes produce all the ephrinAs and Schwann cells produce the receptors EphA2, EphA4, and EphA7. Several ephrinAs inhibit Schwann cell migration on laminin, with ephrinA5 being the most effective. Blocking the EphA receptors with excess EphA4–Fc increases Schwann cell migration on astrocytes and improves Schwann–astrocyte intermingling. We show that the action of ephrinA5 on Schwann cells is mediated via VAV2. Both clustered ephrinA5 and astrocyte contact increases the phosphorylation of VAV2 in Schwann cells. Knockdown of VAV2 abrogates the inhibitory effect of clustered ephrinA5 on migration and increases the ability of Schwann cells to migrate on astrocytes. In addition, we found a role for ephrinA5 in inhibiting Schwann cell integrin signaling and function. Overall, we suggest that Eph/ephrin interactions inhibit Schwann cell migration and intermingling with astrocytes via VAV signaling affecting integrin function.
Navigational Decision Making in Drosophila Thermotaxis
Authors: Luo Linjiao , Gershow Marc , Rosenzweig Mark , Kang KyeongJin , Fang-Yen Christopher , Garrity Paul A. , Samuel Aravinthan D. T.
Published: March 2010

A mechanistic understanding of animal navigation requires quantitative assessment of the sensorimotor strategies used during navigation and quantitative assessment of how these strategies are regulated by cellular sensors. Here, we examine thermotactic behavior of theDrosophila melanogasterlarva using a tracking microscope to study individual larval movements on defined temperature gradients. We discover that larval thermotaxis involves a larger repertoire of strategies than navigation in smaller organisms such as motile bacteria andCaenorhabditis elegans. Beyond regulating run length (i.e., biasing a random walk), theDrosophila melanogasterlarva also regulates the size and direction of turns to achieve and maintain favorable orientations. Thus, the sharp turns in a larva's trajectory represent decision points for selecting new directions of forward movement. The larva uses the same strategies to move up temperature gradients during positive thermotaxis and to move down temperature gradients during negative thermotaxis. Disrupting positive thermotaxis by inactivating cold-sensitive neurons in the larva's terminal organ weakens all regulation of turning decisions, suggesting that information from one set of temperature sensors is used to regulate all aspects of turning decisions. TheDrosophila melanogasterlarva performs thermotaxis by biasing stochastic turning decisions on the basis of temporal variations in thermosensory input, thereby augmenting the likelihood of heading toward favorable temperatures at all times.
Gap Junctions/Hemichannels Modulate Interkinetic Nuclear Migration in the Forebrain Precursors
Authors: Liu Xiuxin , Hashimoto-Torii Kazue , Torii Masaaki , Ding Chen , Rakic Pasko
Published: March 2010

During mitotic division in the telencephalic proliferative ventricular zone (VZ), the nuclei of the neural precursors move basally away from the ventricular surface for DNA synthesis, and apically return to the surface for mitotic division; a process known as interkinetic migration or “to-and-fro” nuclear translocation. The cell, which remains attached to the ventricular surface, either continues cycling, or exits the cycle and migrates to the subventricular zone or the developing cortical plate. Although gap junctions/hemichannels are known to modulate DNA synthesis via Ca2+waves, the role of Ca+oscillations and the mechanism of nuclear translocation in the VZ precursors are unclear. Here, we provide evidence that, during apical nuclear migration, VZ precursors display dynamic spontaneous Ca2+transients, which depend on functional gap junctions/hemichannels via ATP release and Ca2+-mobilizing messenger diffusion. Furthermore, we found that blocking gap junctions/hemichannels or short hairpin RNA-mediated knockdown of Cx43 (connexin 43) retards the apically directed interkinetic nuclear migration accompanied with changes in the nuclear length/width ratio. In addition, we demonstrated that blocking functional gap junctions/hemichannels induces phosphorylation of small GTPase cdc42 in the VZ precursors. The basal phase of interkinetic migration is much slower and appears to be mediated passively by mechanical forces after cell division. Our findings indicate that functional interference with gap junctions/hemichannels during embryonic development may lead to abnormal corticogenesis and dysfunction of the cerebral cortex in adult organisms.
Estradiol-Induced Object Memory Consolidation in Middle-Aged Female Mice Requires Dorsal Hippocampal Extracellular Signal-Regulated Kinase and Phosphatidylinositol 3-Kinase Activation
Authors: Fan Lu , Zhao Zaorui , Orr Patrick T. , Chambers Cassie H. , Lewis Michael C. , Frick Karyn M.
Published: March 2010

We previously demonstrated that dorsal hippocampal extracellular signal-regulated kinase (ERK) activation is necessary for 17β-estradiol (E2) to enhance novel object recognition in young ovariectomized mice (Fernandez et al., 2008). Here, we asked whether E2has similar memory-enhancing effects in middle-aged and aged ovariectomized mice, and whether these effects depend on ERK and phosphatidylinositol 3-kinase (PI3K)/Akt activation. We first demonstrated that intracerebroventricular or intrahippocampal E2infusion immediately after object recognition training enhanced memory consolidation in middle-aged, but not aged, females. The E2-induced enhancement in middle-aged females was blocked by intrahippocampal inhibition of ERK or PI3K activation. Intrahippocampal or intracerebroventricular E2infusion in middle-aged females increased phosphorylation of p42 ERK in the dorsal hippocampus 15 min, but not 5 min, after infusion, an effect that was blocked by intrahippocampal inhibition of ERK or PI3K activation. Dorsal hippocampal PI3K and Akt phosphorylation was increased 5 min after intrahippocampal or intracerebroventricular E2infusion in middle-aged, but not aged, females. Intracerebroventricular E2infusion also increased PI3K phosphorylation after 15 min, and this effect was blocked by intrahippocampal PI3K, but not ERK, inhibition. These data demonstrate for the first time that activation of dorsal hippocampal PI3K/Akt and ERK signaling pathways is necessary for E2to enhance object recognition memory in middle-aged females. They also reveal that similar dorsal hippocampal signaling pathways mediate E2-induced object recognition memory enhancement in young and middle-aged females and that the inability of E2to activate these pathways may underlie its failure to enhance object recognition in aged females.
Two Modes of Release Shape the Postsynaptic Response at the Inner Hair Cell Ribbon Synapse
Authors: Grant Lisa , Yi Eunyoung , Glowatzki Elisabeth
Published: March 2010

Cochlear inner hair cells (IHCs) convert sounds into receptor potentials and via their ribbon synapses into firing rates in auditory nerve fibers. Multivesicular release at individual IHC ribbon synapses activates AMPA-mediated EPSCs with widely ranging amplitudes. The underlying mechanisms and specific role for multivesicular release in encoding sound are not well understood. Here we characterize the waveforms of individual EPSCs recorded from afferent boutons contacting IHCs and compare their characteristics in immature rats (postnatal days 8–11) and hearing rats (postnatal days 19–21). Two types of EPSC waveforms were found in every recording: monophasic EPSCs, with sharp rising phases and monoexponential decays, and multiphasic EPSCs, exhibiting inflections on rising and decaying phases. Multiphasic EPSCs exhibited slower rise times and smaller amplitudes than monophasic EPSCs. Both types of EPSCs had comparable charge transfers, suggesting that they were activated by the release of similar numbers of vesicles, which for multiphasic EPSCs occurred in a less coordinated manner. On average, a higher proportion of larger, monophasic EPSCs was found in hearing compared to immature rats. In addition, EPSCs became significantly faster with age. The developmental increase in size and speed could improve auditory signaling acuity. Multiphasic EPSCs persisted in hearing animals, in some fibers constituting half of the EPSCs. The proportion of monophasic versus multiphasic EPSCs varied widely across fibers, resulting in marked heterogeneity of amplitude distributions. We propose that the relative contribution of two modes of multivesicular release, generating monophasic and multiphasic EPSCs, may underlie fundamental characteristics of auditory nerve fibers.
The Subthreshold Relation between Cortical Local Field Potential and Neuronal Firing Unveiled by Intracellular Recordings in Awake Rats
Authors: Okun Michael , Naim Amir , Lampl Ilan
Published: March 2010

In most of thein vivoelectrophysiological studies of cortical processing, which are extracellular, the spike-triggered local field potential average (LFP STA) is the measure used to estimate the correlation between the synaptic inputs of individual neuron and the local population. To understand how the magnitude and shape of LFP STA reflect the underlying correlation of synaptic activities, the membrane potential of the firing neuron has to be recorded together with the LFP. Using intracellular recordings from the cortex of awake rats, we found that for a large range of firing rates and for different behavioral states, the LFP STA represents both in its waveform and its magnitude the cross-correlation between the membrane potential of the neuron and the LFP. This data, supported by further analysis, suggests that LFP STA does not represent large network events specific to the spike times, but rather the synchrony between the mean synaptic activity of the population and the membrane potential of the single neuron, present both around spike times and in the intervals between spikes. Furthermore, it introduces a novel interpretation of the available data from unit and LFP extracellular recording experiments.
Longitudinal Magnetic Resonance Imaging Study of Cortical Development through Early Childhood in Autism
Authors: Schumann Cynthia M. , Bloss Cinnamon S. , Barnes Cynthia Carter , Wideman Graham M. , Carper Ruth A. , Akshoomoff Natacha , Pierce Karen , Hagler Donald , Schork Nicholas , Lord Catherine , Courchesne Eric
Published: March 2010

Cross-sectional magnetic resonance imaging (MRI) studies have long hypothesized that the brain in children with autism undergoes an abnormal growth trajectory that includes a period of early overgrowth; however, this has never been confirmed by a longitudinal study. We performed the first longitudinal study of brain growth in toddlers at the time symptoms of autism are becoming clinically apparent using structural MRI scans at multiple time points beginning at 1.5 years up to 5 years of age. We collected 193 scans on 41 toddlers who received a confirmed diagnosis of autistic disorder at ∼48 months of age and 44 typically developing controls. By 2.5 years of age, both cerebral gray and white matter were significantly enlarged in toddlers with autistic disorder, with the most severe enlargement occurring in frontal, temporal, and cingulate cortices. In the longitudinal analyses, which we accounted for age and gender effect, we found that all regions (cerebral gray, cerebral white, frontal gray, temporal gray, cingulate gray, and parietal gray) except occipital gray developed at an abnormal growth rate in toddlers with autistic disorder that was mainly characterized by a quadratic age effect. Females with autistic disorder displayed a more pronounced abnormal growth profile in more brain regions than males with the disorder. Given that overgrowth clearly begins before 2 years of age, future longitudinal studies would benefit from inclusion of even younger populations as well as further characterization of genetic and other biomarkers to determine the underlying neuropathological processes causing the onset of autistic symptoms.
Stimulation of the Frontal Eye Field Reveals Persistent Effective Connectivity after Controlled Behavior
Authors: Akaishi Rei , Morishima Yosuke , Rajeswaren Vivian P. , Aoki Shigeki , Sakai Katsuyuki
Published: March 2010

Our ability to choose nonhabitual controlled behavior instead of habitual automatic behavior is based on a flexible control mechanism subserved by neural activity representing the behavior-guiding rule. However, it has been shown that the behavior slows down more when switching from controlled to automatic behavior than vice versa. Here we show that persistent effective connectivity of the neural network after execution of controlled behavior is responsible for the behavioral slowing on a subsequent trial. We asked normal human subjects to perform a prosaccade or antisaccade task based on a cue and examined the effective connectivity of the neural network based on the pattern of neural impulse transmission induced by stimulation of the frontal eye field (FEF). Effective connectivity during the task preparation period was dependent on the task that subjects had performed on the previous trial, regardless of the upcoming task. The strength of this persistent effective connectivity was associated with saccade slowing especially on trials after controlled antisaccade. In contrast, the pattern of regional activation changed depending on the upcoming task regardless of the previous task and the decrease in activation was associated with errors in upcoming antisaccade task. These results suggest that the effective connectivity examined by FEF stimulation reflects a residual functional state of the network involved in performance of controlled antisaccade and its persistence may account for the behavioral slowing on the subsequent trial.
Joint Design of Control and Communication in Wireless Networked Control SystemsGemeinsamer Entwurf von Regelung und Kommunikation für funkbasierte Regelungssysteme
Authors: Chamaken Alain , Litz Lothar
Published: March 2010

The control performance of a wireless networked control system is a complex function of control structure, control system parameters e. g. sampling period, controller gain and communication system structure and parameters e. g. random delay, packet loss. Further limitations may arise from low energy low performance computing nodes. In order to predict or even optimize the control performance, a joint design of both the control system with appropriate control structures and the communication system with appropriate communication protocols is intended. In this contribution a wireless networked control system where sensors, controller, and actuator communicate over a dedicated wireless network is analyzed and implemented. It is shown how to use different controllers in conjunction with dedicated communication protocols to stabilize an inverted pendulum equipped with low power low energy wireless nodes. Experimental results are provided to show the effectiveness of the method.
Regelung und Sicherheitsanalyse einer Gruppe Massenpunktfahrzeuge mit Hilfe energiebasierter MethodenControl and Safety Analysis of a Group of Point Mass Vehicles Using Energy Methods
Authors: Chávez Grunewald Martín Guillermo , Ben Makhlouf Ibtissem , Diab Hial , Mut Vicente , Kowalewski Stefan , Abel Dirk
Published: March 2010

Dieser Beitrag beschreibt die energiebasierte Regelung einer Gruppe von Fahrzeugen, die als Massenpunkte in der Ebene modelliert werden. Es wird zuerst eine Umformung der kinetischen Energie durchgeführt, sodass die Komponenten der Geschwindigkeitsvektoren, welche die Abstände verändern, bei der Regelung unterschiedlich bestraft werden. Darüber hinaus werden virtuelle potentielle Energie und dissipative Terme hinzugefügt, um das System in einer Kolonnenkonfiguration zu stabilisieren. Zum Schluss werden ein Stabilitätsbeweis sowie eine Sicherheitsanalyse auf der Basis hybrider Automaten durchgeführt und die Ergebnisse vorgestellt.
Autonomie und Kooperation in seriell gekoppelten SystemenAutonomy and Cooperation in Serially Interconnected Systems
Authors: Demir Ozan , Lunze Jan
Published: March 2010

Funkbasierte Kommunikationsnetze bieten die Möglichkeit, Informationen zwischen sich bewegenden Objekten zu übertragen und die Informationsverbindung immer dann zu nutzen, wenn eine Annäherung der Objekte untereinander eine Koordination ihrer Regelungen erfordert. Die wichtigste Frage bei derartigen Regelungen lautet: Welche Informationskopplungen sind nützlich und welche Verbesserungen der Regelgüte können durch diese Informationskopplungen erreicht werden? Diese Frage wird für Systeme beantwortet, die aus einer Reihenschaltung von Teilsystemen mit gleichartiger Dynamik bestehen und deren Regelung bei schwacher Kopplung eine hinreichende Autonomie der Teilsysteme und bei starker Kopplung ein kooperatives Verhalten der Teilsysteme im Sinne der Güteforderungen an das Gesamtsystem gewährleistet.
Robuste modellprädiktive Regelung kommunizierender FahrzeugkolonnenRobust Predictive Control of Platooning Vehicles Using Communication
Authors: Dold Johannes , Stursberg Olaf
Published: March 2010

Motiviert durch die Regelung autonomer, in einer Kolonne fahrender Fahrzeuge, wird in diesem Artikel eine neue Methode zur robusten modellprädiktiven Regelung (RMPR) von verteilten Systemen mit Kettenstruktur vorgestellt. Die Teilsysteme werden durch lokale Zustände modelliert, wobei die Eingänge des vorangehenden Teilsystems als beschränkte Störung betrachtet werden. Ausgehend von einer von Kerrigan et al. vorgestellten Methode zur robusten modellprädiktiven Regelung nicht-verteilter Systeme wird für das verteilte System gezeigt, dass die Lösbarkeit des Optimierungsproblems im Anfangszustand die Lösbarkeit für alle folgenden Zeitschritte garantiert. Im Allgemeinen kann die gefundene Lösung sehr konservativ sein und zu hohen Kosten führen. Deshalb wird im zweiten Teil des Artikels ein Konzept vorgestellt, bei welchem Kommunikation zwischen den Teilsystemen verwendet wird, um die Regelgüte zu erhöhen und eine weniger konservative Lösung zu erhalten.
Two Complementary Approaches to Event-based ControlZwei komplementäre Zugänge zur ereignisbasierten Regelung
Authors: Grüne Lars , Jerg Stefan , Junge Oliver , Lehmann Daniel , Lunze Jan , Müller Florian , Post Marcus
Published: March 2010

Event-based control aims at reducing the communication effort within a control loop by closing the feedback loop only if an event indicates e. g. a substantial control error. This paper proposes two new methods for event-based control that conjointly guarantee ultimate boundedness of the event-based control loop. The global approach faces the problem of driving a system from its initial state into a desired target set in the state space, whereas the local approach aims at keeping the system state within the target set. Both methods are experimentally evaluated by their application to a thermofluid process.
High prevalence of polycystic ovary syndrome characteristics in girls with euthyroid chronic lymphocytic thyroiditis: a case–control study
Authors: Ganie Mohd Ashraf , Marwaha Raman Kumar , Aggarwal Rashmi , Singh Satveer
Published: March 2010

Objective

The aim was to find the prevalence of polycystic ovary syndrome (PCOS) phenotype in adolescent euthyroid girls with chronic lymphocytic thyroiditis (CLT).

Design

This was a prospective case–control study as part of an ongoing community-wide thyroid survey in Indian schools.

Methods

One hundred and seventy-five girls with euthyroid CLT and 46 age-matched non-CLT girls underwent clinical, biochemical, hormonal, and ultrasonographic evaluation for diagnosis of PCOS by Rotterdam 2003 criteria. All subjects underwent serum sampling for LH, FSH, testosterone, DHEAS, free thyroxine, TSH, and anti-thyroid peroxidase (TPO) antibodies. Oral glucose tolerance test (OGTT) was undertaken for plasma glucose and insulin.

Results

Significantly higher prevalence of PCOS was noted in girls with euthyroid CLT when compared to their control counterparts (46.8 vs 4.3%,P=0.001). The CLT girls had higher body mass index, waist circumference, and systolic blood pressure (P=0.001). Mean number of menstrual cycles/year was 8.4±3.5 vs 10.1±1.4, and mean Ferriman–Gallwey score was 11.9±3.5 vs 3.0±2.4 (P=0.001) in cases versus controls respectively. The fasting and postprandial glucose and serum cholesterol were also higher in the cases (P=0.001). Homeostasis model assessment-insulin resistance was 4.4±4.2 vs 2.3±2.7 in the cases versus controls (P=0.001).

Conclusion

Higher prevalence of PCOS characteristics in euthyroid CLT girls when compared to controls suggest possible role of autoimmune phenomenon in the etiopathogenesis of PCOS. Further studies are required to understand the pathogenic link between these two disorders.
Neurocysticercosis: relationship between Taenia antigen levels in CSF and MRI
Authors: Abraham Ronaldo , Livramento José Antonio , Leite Cláudia da Costa , Pardini Alessandra Xavier , Vaz Adelaide José , Machado Luís dos Ramos
Published: March 2010

OBJECTIVE: To determine the relationship between Taenia antigen (TA) detection in cerebrospinal fluid (CSF) and magnetic resonance imaging (MRI) findings in patients with definite diagnosis of neurocysticercosis (NC). METHOD: Sixty-three patients with definite diagnosis of NC were submitted to a MRI of the brain, and to a CSF examination, with a meticulous search for TA by ELISA. RESULTS: TA detection was positive in 36 patients (57.1%). A total of 836 lesions were analyzed, greatly within the cerebral parenchyma (98.7 of the lesions). Intact or non-degenerating cysts were the most common evolutive phase observed (50.4% of all lesions), 22.1% were degenerating cysts and 19.5% calcified cysts. We observed a significant relationship between TA levels detected and the total number of lesions and the number of non-degenerating cysts, but not with calcified lesions. CONCLUSION: According to our results, we propose at least four important types of contribution: (1) TA detection may allow etiologic diagnosis in transitional phases of NC, with non-characteristic images; (2) in final stages of evolution of cysticercoids in the CNS, lesions may not appear on CT or MRI, and TA detection may contribute to a definite etiologic diagnosis; (3) TA detection may permit diagnosis of NC in some patients with previous negative tests for antibody detection in CSF; (4) TA detection may represent an accurate marker of disease activity in the epileptic form of NC.
Neurotological symptoms and academic performance of university students
Authors: Marques Marcia Mattos , Ganança Mauricio Malavasi , Marques Carolina Mattos , Ganança Fernando Freitas , Caovilla Heloisa Helena
Published: March 2010

OBJECTIVE: To compare the academic performance of university students with or without neurotological symptoms. METHOD: 100 students enrolled in the Biomedical Sciences Graduate School - Medical Modality of UNIFESP-EPM in 2007 and answered a neurotological screening questionnaire. RESULTS: The symptoms presented once, sometimes, many times or always, in a decreasing order of prevalence, were headache (74.0%), difficulty with concentration (57.0%), lack of memory (45.0%), physical indisposition, nausea /dizziness when in moving vehicle (37.0%), fainting (27.0%), nausea (26.0%), sensation of fullness in the ear (26.0%), hypersensitivity to sounds (26.0%), tinnitus (22.0%), vertigo and other kinds of dizziness (21.0%), imbalance when walking (21.0%), difficulty in hearing (21.0%), imminent sensation of fainting (11.0%) and vomiting (8.0%), alone or in different associations; convulsion was not mentioned. The final academic performance score ranged from 5.1 to 10.0. CONCLUSION: University students with or without neurotological symptoms have manifested similar academic performance.
Sleep disorders frequency in post-polio syndrome patients caused by periodic limb movements
Authors: Araujo Maria Auxiliadora de Paiva , Silva Tatiana Mesquita e , Moreira Gustavo Antonio , Pradella-Hallinan Márcia , Tufik Sergio , Oliveira Acary Souza Bulle
Published: March 2010

Post-polio syndrome (PPS) in individuals with polio longer than 15 years is characterized by weakness and/or muscle fatigue, deficit of deglutition and breath and periodic limb movements (PLM) during sleep. We undertook a review of 99 patients with PPS, and assessed the frequency of PLM through polysomnographic recordings at our sleep disorders unit. The total number of PLM, total time of sleep (TTS), efficiency of sleep (EfS), awaking index (AI) and apnea-hypopnea index (AHI) were analyzed. Sixteen patients presented PLM in excess of 5 for the entire night. When comparing these with the group without PLM, a correlation was found (p=0.001). Significant difference was found for the correlation of the parameters: IAH, ID, TTS and EfS when compared the two groups. There is a close relationship between PPS and PLM.
Cross-cultural adaptation and validation of als Functional Rating Scale-Revised in Portuguese language
Authors: Guedes Keyte , Pereira Cecília , Pavan Karina , Valério Berenice Cataldo Oliveira
Published: March 2010

The aim of this study is the cross-cultural, as well as to validate in Portuguese language the Amyotrophic Lateral Sclerosis Functional Rating Scale - Revised (ALSFRS-R). We performed a prospective study of individuals with amyotrophic lateral sclerosis (ALS) clinically defined. The scale, after obtaining the final version in Portuguese, was administered in 22 individuals and three weeks after re-applied. There were no significant differences between the application and reapplication of the scale (p=0.069). The linear regression and internal consistency measured by Pearson correlation and alpha Conbrach were significant with r=0.975 e α=0.934. The reliability test-retest demonstrated by intraclass correlation coefficient was strong with ICC=0.975. Therefore, this version proved to be applicable, reliable and easy to be conducted in clinical practice and research.