bluuebunny/crossref_metadata_2025 huggingface dataset:
Promotional piracy
Authors: Croxson Karen
Published: December 2007

Unauthorized copying of goods can displace current sales. At the same time, those who pirate a product may help alert others to its existence, leading to stronger future demand. I discuss a simple model which leaves room for both effects. Piracy's net profit impact is linked to the whereabouts of people in the space of willingness‐to‐pay and personal piracy cost. Considerations of location help demystify empirical puzzles, such as why some (computer games manufacturers) deploy stringent copy protection when elsewhere (business software) controls appear more relaxed.
Role of a Sodium-Dependent Symporter Homologue in the Thermosensitivity of β-Lactam Antibiotic Resistance and Cell Wall Composition in
Staphylococcus aureus
Authors: Sieradzki Krzysztof , Chung Marilyn , Tomasz Alexander
Published: December 2007

Expression of high-level β-lactam resistance is known to be thermosensitive in many methicillin-resistant
Staphylococcus aureus
(MRSA) strains, including strain COL, in which the high methicillin MIC for cultures grown at 37°C (800 μg/ml) was reduced to 12 μg/ml at 42°C. COL grew faster at 42°C than at 37°C and at the higher temperature produced cell walls of abnormal composition: there was an over-representation of the monomeric muropeptide without the oligoglycine chain and an increase in the representation of multimers that contained this wall component as the donor molecule. Screening of a Tn
551
insertional library for mutants, in which the high and homogenous β-lactam antibiotic resistance of strain COL is retained at 42°C, identified mutant C245, which expressed high-level methicillin resistance and produced a cell wall of normal composition independent of the temperature. The Tn
551
inactivated gene was found, by homology search, to encode for a sodium-dependent symporter, homologues of which are ubiquitous in both prokaryotic and eukaryotic genomes. Inactivation of this putative symporter in several heteroresistant clinical MRSA isolates caused striking increases in the level of their β-lactam resistance.
Pharmacokinetic Interaction between Fosamprenavir-Ritonavir and Rifabutin in Healthy Subjects
Authors: Ford Susan L. , Chen Ya-Chi , Lou Yu , Borland Julie , Min Sherene S. , Yuen Geoffrey J. , Shelton Mark J.
Published: December 2007

Rifabutin (RFB) is administered for treatment of tuberculosis and
Mycobacterium avium
complex infection, including use for patients coinfected with human immunodeficiency virus (HIV). Increased systemic exposure to RFB and its equipotent active metabolite, 25-
O
-desacetyl-RFB (dAc-RFB), has been reported during concomitant administration of CYP3A4 inhibitors, including ritonavir (RTV), lopinavir, and amprenavir (APV); therefore, a reduction in the RFB dosage is recommended when it is coadministered with these protease inhibitors. Fosamprenavir (FPV), the phosphate ester prodrug of the HIV type 1 protease inhibitor APV, is administered either with or without RTV. A randomized, open-label, two-period, two-sequence, balanced, crossover drug interaction study was conducted with 22 healthy adult subjects to compare steady-state plasma RFB pharmacokinetic parameters during concomitant administration of FPV-RTV (700/100 mg twice a day [BID]) with a 75%-reduced RFB dose (150 mg every other day [QOD]) to the standard RFB regimen (300 mg once per day [QD]) by geometric least-squares mean ratios. Relative to results with RFB (300 mg QD), coadministration of dose-adjusted RFB with FPV-RTV resulted in an unchanged RFB area under the concentration-time curve for 0 to 48 h (AUC
0-48
) and a 14% decrease in the maximum concentration of drug in plasma (
C
max
), whereas the AUC
0-48
and
C
max
of dAc-RFB were increased by 11- and 6-fold, respectively, resulting in a 64% increase in the total antimycobacterial AUC
0-48
. Relative to historical controls, the plasma APV AUC from 0 h to the end of the dosing interval (AUC
0-τ
) and
C
max
were increased ∼35%, and the concentration at the end of the dosing interval at steady state was unchanged following coadministration of RFB with FPV-RTV. The safety profile of the combination of RFB and FPV-RTV was consistent with previously described events with RFB or FPV-RTV alone. Based on the results of this study, a reduction in the RFB dose by ≥75% (to 150 mg QOD or three times per week) is recommended when it is coadministered with FPV-RTV (700/100 mg BID).
Telithromycin and Quinupristin-Dalfopristin Induce Delayed Death in
Plasmodium falciparum
Authors: Barthel Diana , Schlitzer Martin , Pradel Gabriele
Published: December 2007

Antibacterial agents are used in malaria therapy due to their effect on two prokaryote organelles, the mitochondrion and the apicoplast. We demonstrate here that the ribosome-blocking antibiotics telithromycin and quinupristin-dalfopristin, but not linezolid, inhibit the growth of
Plasmodium falciparum
. Both drugs induce delayed death in the parasite, suggesting that their effect involves the impairment of apicoplast translation processes.
Vancomycin-Resistant
Staphylococcus aureus
Isolates Associated with Inc18-Like
vanA
Plasmids in Michigan
Authors: Zhu Wenming , Clark Nancye C. , McDougal Linda K. , Hageman Jeffery , McDonald L. Clifford , Patel Jean B.
Published: December 2007

Five of the seven cases of vancomycin-resistant
Staphylococcus aureus
(VRSA) infection identified to date have occurred in southeastern Michigan. VRSA isolates from the four most recent cases (all from Michigan) were characterized. The
vanA
gene was localized to a single plasmid in each VRSA isolate. The pulsed-field gel electrophoresis patterns of chromosomal DNA and the restriction profile of the plasmid demonstrated that the four isolates were unique and differed from the first three VRSA isolates. Vancomycin-resistant
Enterococcus
(VRE) isolates, all of which were
Enterococcus faecalis
, were recovered from case patients 4 to 6. Each VRE isolate transferred vancomycin resistance to
E. faecalis
JH2-2 by conjugation. PCRs for
vanA
and the Inc18-like plasmid genes
traA
and
repR
confirmed the presence of an Inc18-like
vanA
plasmid in all VRE isolates and transconjugants. An Inc18-like
vanA
plasmid was identified in the VRSA isolate from case patient 7. These findings suggest a role of Inc18-like plasmids as
vanA
donors.
In Vitro Interactions between Tacrolimus and Azoles against
Candida albicans
Determined by Different Methods
Authors: Sun Shujuan , Li Yan , Guo Qiongjie , Shi Changwen , Yu Jinlong , Ma Lin
Published: December 2007

Combination therapy could be of use for the treatment of fungal infections, especially those caused by drug-resistant fungi. However, the methods and approaches used for data generation and result interpretation need further optimizing. The fractional inhibitory concentration index (FICI) is the most commonly used method, but it has several drawbacks in characterizing antifungal drug interaction. Alternatively, some new methods can be used such as the Δ
E
model (difference between the predicted and measured fungal growth percentages) and the response surface approach, which uses the concentration-effect relationship over the whole concentration range instead of just the MIC. In the present study, in vitro interactions between tacrolimus (FK506) and three azoles—fluconazole (FLC), itraconazole (ITR), and voriconazole (VRC)-against
Candida albicans
were evaluated by the checkerboard microdilution method and time-killing test. The intensity of the interactions was determined by visual reading and the spectrophotometric method in a checkerboard assay, and the nature of the interactions was assessed by nonparametric models of FICI and Δ
E
. Colony counting and colorimetric viable detection methods (2,3-bis {2-methoxy-4-nitro-5-[(sulfenylamino) carbonyl]-2H-tetrazolium hydroxide} [XTT] reduction test) were used for evaluating the combination antifungal effects over time. Synergistic and indifferent effects were found for the combination of FK506 and azoles against azole-sensitive strains, while strong synergy was found against azole-resistant strains analyzed by FICI. The Δ
E
model gave more consistent results with FICI. The positive interactions were also confirmed by the time-killing test. Our findings suggest a potential role for combination therapy with calcineurin pathway inhibitors and azoles to augment activity against resistant
C. albicans
.
Inhibition of ABC Transporters Abolishes Antimony Resistance inLeishmaniaInfection
Authors: Mookerjee Basu Jayati , Mookerjee Ananda , Banerjee Rajdeep , Saha Manik , Singh Subhankar , Naskar Ksudiram , Tripathy Gayetri , Sinha Prabhat K. , Pandey Krishna , Sundar Shyam , Bimal Sanjeev , Das Pradip K. , Choudhuri Soumitra K. , Roy Syamal
Published: December 2007

The emergence of antimony (Sb) resistance has jeopardized the treatment of visceral leishmaniasis in various countries. Previous studies have considered the part played by leishmanial parasites in antimony resistance, but the involvement of host factors in the clinical scenario remained to be investigated. Here we show that unlike infection with Sb-sensitive (Sbs)Leishmania donovani, infection with Sb-resistant (Sbr)L. donovaniinduces the upregulation of multidrug resistance-associated protein 1 (MRP1) and permeability glycoprotein (P-gp) in host cells, resulting in a nonaccumulation of intracellular Sb following treatment with sodium antimony gluconate (SAG) favoring parasite replication. The inhibition of MRP1 and P-gp with resistance-modifying agents such as lovastatin allows Sb accumulation and parasite killing within macrophages and offers protection in an animal model in which infection with SbrL. donovaniis otherwise lethal. The occurrence of a similar scenario in clinical cases is supported by the findings that unlike monocytes from SAG-sensitive kala-azar (KA) patients, monocytes from SAG-unresponsive KA patients overexpress P-gp and MRP1 and fail to accumulate Sb following in vitro SAG treatment unless pretreated with inhibitors of ABC transporters. Thus, the expression status of MRP1 and P-gp in blood monocytes may be used as a diagnostic marker for Sb resistance and the treatment strategy can be designed accordingly. Our results also indicate that lovastatin, which can inhibit both P-gp and MRP1, might be beneficial for reverting Sb resistance in leishmaniasis as well as drug resistance in other clinical situations, including cancer.
MisR/MisS Two-Component Regulon in
Neisseria meningitidis
Authors: Tzeng Yih-Ling , Kahler Charlene M. , Zhang Xinjian , Stephens David S.
Published: December 2007

Two-component regulatory systems are involved in processes important for bacterial pathogenesis. Inactivation of the
misR
/
misS
system in
Neisseria meningitidis
results in the loss of phosphorylation of the lipooligosaccharide inner core and causes attenuation in a mouse model of meningococcal infection. One hundred seventeen (78 up-regulated and 39 down-regulated) potential regulatory targets of the MisR/MisS (MisR/S) system were identified by transcriptional profiling of the NMB
misR
mutant and the parental wild-type meningococcal strain NMB. The regulatory effect was further confirmed in a subset of target genes by quantitative real-time PCR and β-galactosidase transcriptional fusion reporter assays. The MisR regulon includes genes encoding proteins necessary for protein folding in the bacterial cytoplasm and periplasm, transcriptional regulation, metabolism, iron assimilation, and type I protein transport. Mutation in the MisR/S system caused increased sensitivity to oxidative stress and also resulted in decreased susceptibility to complement-mediated killing by normal human serum. To identify the direct targets of MisR regulation, electrophoretic mobility shift assays were carried out using purified MisR-His
6
protein. Among 22 genes examined,
misR
directly interacted with 14 promoter regions. Six promoters were further investigated by DNase I protection assays, and a MisR-binding consensus sequence was proposed. Thus, the direct regulatory targets of MisR and the minimal regulon of the meningococcal MisR/S two-component signal transduction system were characterized. These data indicate that the MisR/S system influences a wide range of biological functions in
N. meningitidis
either directly or via intermediate regulators.
Neutrophils Contribute to Development of a Protective Immune Response during Onset of Infection withLeishmania donovani
Authors: McFarlane Emma , Perez Cynthia , Charmoy Mélanie , Allenbach Cindy , Carter K. Christine , Alexander James , Tacchini-Cottier Fabienne
Published: December 2007

Neutrophils are key components of the inflammatory response and as such contribute to the killing of microorganisms. In addition, recent evidence suggests their involvement in the development of the immune response. The role of neutrophils during the first weeks post-infection withLeishmania donovaniwas investigated in this study. WhenL. donovani-infected mice were selectively depleted of neutrophils with the NIMP-R14 monoclonal antibody, a significant increase in parasite numbers was observed in the spleen and bone marrow and to a lesser extent in the liver. Increased susceptibility was associated with enhanced splenomegally, a delay in the maturation of hepatic granulomas, and a decrease in inducible nitric oxide synthase expression within granulomas. In the spleen, neutrophil depletion was associated with a significant increase in interleukin 4 (IL-4) and IL-10 levels and reduced gamma interferon secretion by CD4+and CD8+T cells. Increased production of serum IL-4 and IL-10 and higher levels ofLeishmania-specific immunoglobulin G1 (IgG1) versus IgG2a revealed the preferential induction of Th2 responses in neutrophil-depleted mice. Altogether, these data suggest a critical role for neutrophils in the early protective response againstL. donovani, both as effector cells involved in the killing of the parasites and as significant players influencing the development of a protective Th1 immune response.
Gliding and the Functional Origins of Flight: Biomechanical Novelty or Necessity?
Authors: Dudley Robert , Byrnes Greg , Yanoviak Stephen P. , Borrell Brendan , Brown Rafe M. , McGuire Jimmy A.
Published: December 2007

A biomechanically parsimonious hypothesis for the evolution of flapping flight in terrestrial vertebrates suggests progression within an arboreal context from jumping to directed aerial descent, gliding with control via appendicular motions, and ultimately to powered flight. The more than 30 phylogenetically independent lineages of arboreal vertebrate gliders lend strong indirect support to the ecological feasibility of such a trajectory. Insect flight evolution likely followed a similar sequence, but is unresolved paleontologically. Recently described falling behaviors in arboreal ants provide the first evidence demonstrating the biomechanical capacity for directed aerial descent in the complete absence of wings. Intentional control of body trajectories as animals fall from heights (and usually from vegetation) likely characterizes many more taxa than is currently recognized. Understanding the sensory and biomechanical mechanisms used by extant gliding animals to control and orient their descent is central to deciphering pathways involved in flight evolution.
Applications of Flow Cytometry to Evolutionary and Population Biology
Authors: Kron Paul , Suda Jan , Husband Brian C.
Published: December 2007

Flow cytometry, a method of rapidly characterizing optical properties of cells and cell components within individuals, populations, and communities, is advancing research in several areas of ecology, systematics, and evolutionary biology. Measuring the light emitted or scattered from cells or cell components, often in combination with specific stains, allows a multitude of physical and genetic attributes to be evaluated simultaneously and the resulting information to be rapidly processed. As a result, the technique has enabled large-scale comparative analyses of genome-size evolution, taxonomic identification and delineation, and studies of polyploids, reproductive biology, and experimental evolution. It is also being used to characterize the structure and composition of microbial communities. Here, we outline the nature of these contributions, as well as future applications, and provide an online summary of protocols and sampling methods.
The Social Lives of Microbes
Authors: West Stuart A. , Diggle Stephen P. , Buckling Angus , Gardner Andy , Griffin Ashleigh S.
Published: December 2007

Our understanding of the social lives of microbes has been revolutionized over the past 20 years. It used to be assumed that bacteria and other microorganisms lived relatively independent unicellular lives, without the cooperative behaviors that have provoked so much interest in mammals, birds, and insects. However, a rapidly expanding body of research has completely overturned this idea, showing that microbes indulge in a variety of social behaviors involving complex systems of cooperation, communication, and synchronization. Work in this area has already provided some elegant experimental tests of social evolutionary theory, demonstrating the importance of factors such as relatedness, kin discrimination, competition between relatives, and enforcement of cooperation. Our aim here is to review these social behaviors, emphasizing the unique opportunities they offer for testing existing evolutionary theory as well as highlighting the novel theoretical problems that they pose.
The Very Early Stages of Biological Evolution and the Nature of the Last Common Ancestor of the Three Major Cell Domains
Authors: Becerra Arturo , Delaye Luis , Islas Sara , Lazcano Antonio
Published: December 2007

Quantitative estimates of the gene complement of the last common ancestor of all extant organisms, that is, the cenancestor, may be hindered by ancient horizontal gene transfer events and polyphyletic gene losses, as well as by biases in genome databases and methodological artifacts. Nevertheless, most reports agree that the last common ancestor resembled extant prokaryotes. A significant number of the highly conserved genes are sequences involved in the synthesis, degradation, and binding of RNA, including transcription and translation. Although the gene complement of the cenancestor includes sequences that may have originated in different epochs, the extraordinary conservation of RNA-related sequences supports the hypothesis that the last common ancestor was an evolutionary outcome of the so-called RNA/protein world. The available evidence suggests that the cenancestor was not a hyperthermophile, but it is currently not possible to assess its ecological niche or its mode of energy acquisition and carbon sources.
Leucine-enriched essential amino acid and carbohydrate ingestion following resistance exercise enhances mTOR signaling and protein synthesis in human muscle
Authors: Dreyer Hans C. , Drummond Micah J. , Pennings Bart , Fujita Satoshi , Glynn Erin L. , Chinkes David L. , Dhanani Shaheen , Volpi Elena , Rasmussen Blake B.
Published: December 2007

We recently showed that resistance exercise and ingestion of essential amino acids with carbohydrate (EAA+CHO) can independently stimulate mammalian target of rapamycin (mTOR) signaling and muscle protein synthesis in humans. Providing an EAA+CHO solution postexercise can further increase muscle protein synthesis. Therefore, we hypothesized that enhanced mTOR signaling might be responsible for the greater muscle protein synthesis when leucine-enriched EAA+CHOs are ingested during postexercise recovery. Sixteen male subjects were randomized to one of two groups (control or EAA+CHO). The EAA+CHO group ingested the nutrient solution 1 h after resistance exercise. mTOR signaling was assessed by immunoblotting from repeated muscle biopsy samples. Mixed muscle fractional synthetic rate (FSR) was measured using stable isotope techniques. Muscle protein synthesis and 4E-BP1 phosphorylation during exercise were significantly reduced ( P < 0.05). Postexercise FSR was elevated above baseline in both groups at 1 h but was even further elevated in the EAA+CHO group at 2 h postexercise ( P < 0.05). Increased FSR was associated with enhanced phosphorylation of mTOR and S6K1 ( P < 0.05). Akt phosphorylation was elevated at 1 h and returned to baseline by 2 h in the control group, but it remained elevated in the EAA+CHO group ( P < 0.05). 4E-BP1 phosphorylation returned to baseline during recovery in control but became elevated when EAA+CHO was ingested ( P < 0.05). eEF2 phosphorylation decreased at 1 and 2 h postexercise to a similar extent in both groups ( P < 0.05). Our data suggest that enhanced activation of the mTOR signaling pathway is playing a role in the greater synthesis of muscle proteins when resistance exercise is followed by EAA+CHO ingestion.
Progesterone Regulates Cardiac Repolarization Through a Nongenomic Pathway
Authors: Nakamura Hiroaki , Kurokawa Junko , Bai Chang-Xi , Asada Ken , Xu Jun , Oren Ronit V. , Zhu Zheng I. , Clancy Colleen E. , Isobe Mitsuaki , Furukawa Tetsushi
Published: December 2007

Background—

Female sex is an independent risk factor for torsade de pointes in long-QT syndrome. In women, QT interval and torsade de pointes risk fluctuate dynamically during the menstrual cycle and pregnancy. Accumulating clinical evidence suggests a role for progesterone; however, the effect of progesterone on cardiac repolarization remains undetermined.

Methods and Results—

We investigated the effects of progesterone on action potential duration and membrane currents in isolated guinea pig ventricular myocytes. Progesterone rapidly shortened action potential duration, which was attributable mainly to enhancement of the slow delayed rectifier K
+
current (I
Ks
) under basal conditions and inhibition of L-type Ca
2+
currents (I
Ca,L
) under cAMP-stimulated conditions. The effects of progesterone were mediated by nitric oxide released via nongenomic activation of endothelial nitric oxide synthase; this signal transduction likely takes place in the caveolae because sucrose density gradient fractionation experiments showed colocalization of the progesterone receptor c-Src, phosphoinositide 3-kinase, Akt, and endothelial nitric oxide synthase with KCNQ1, KCNE1, and Ca
V
1.2 in the caveolae fraction. We used computational single-cell and coupled-tissue action potential models incorporating the effects of progesterone on I
Ks
and I
Ca,L
; the model reproduces the fluctuations of cardiac repolarization during the menstrual cycle observed in women and predicts the protective effects of progesterone against rhythm disturbances in congenital and drug-induced long-QT syndrome.

Conclusions—

Our data show that progesterone modulates cardiac repolarization by nitric oxide produced via a nongenomic pathway. A combination of experimental and computational analyses of progesterone effects provides a framework to understand complex fluctuations of QT interval and torsade de pointes risks in various hormonal states in women.
Rad GTPase Deficiency Leads to Cardiac Hypertrophy
Authors: Chang Lin , Zhang Jifeng , Tseng Yu-Hua , Xie Chang-Qing , Ilany Jacob , Brüning Jens C. , Sun Zhongcui , Zhu Xiaojun , Cui Taixing , Youker Keith A. , Yang Qinglin , Day Sharlene M. , Kahn C. Ronald , Chen Y. Eugene
Published: December 2007

Background—

Rad (Ras associated with diabetes) GTPase is the prototypic member of a subfamily of Ras-related small G proteins. The aim of the present study was to define whether Rad plays an important role in mediating cardiac hypertrophy.

Methods and Results—

We document for the first time that levels of Rad mRNA and protein were decreased significantly in human failing hearts (n=10) compared with normal hearts (n=3;
P
<0.01). Similarly, Rad expression was decreased significantly in cardiac hypertrophy induced by pressure overload and in cultured cardiomyocytes with hypertrophy induced by 10 μmol/L phenylephrine. Gain and loss of Rad function in cardiomyocytes significantly inhibited and increased phenylephrine-induced hypertrophy, respectively. In addition, activation of calcium-calmodulin–dependent kinase II (CaMKII), a strong inducer of cardiac hypertrophy, was significantly inhibited by Rad overexpression. Conversely, downregulation of CaMKIIδ by RNA interference technology attenuated the phenylephrine-induced hypertrophic response in cardiomyocytes in which Rad was also knocked down. To further elucidate the potential role of Rad in vivo, we generated Rad-deficient mice and demonstrated that they were more susceptible to cardiac hypertrophy associated with increased CaMKII phosphorylation than wild-type littermate controls.

Conclusions—

The present data document for the first time that Rad is a novel mediator that inhibits cardiac hypertrophy through the CaMKII pathway. The present study will have significant implications for understanding the mechanisms of cardiac hypertrophy and setting the basis for the development of new strategies for treatment of cardiac hypertrophy.
Neural Correlates of Preparation for Action Selection as a Function of Specific Task Demands
Authors: Donohue S. E. , Wendelken C. , Bunge Silvia A.
Published: December 2007

Our behavior is frequently guided by rules, or prescribed guides for action. The prefrontal cortex (PFC) has been implicated in the ability to retrieve and use rules in a conscious, effortful manner. Several functional magnetic resonance imaging (fMRI) studies have examined the role of the PFC in rule representation; however, the precise PFC subregions implicated in this function vary from study to study. This observation raises the question of whether there are distinct classes of rules that are represented differentially in the brain. To address this question, an fMRI study was conducted in which participants performed two tasks, each at two levels of difficulty, during acquisition of event-related fMRI data. The response competition task was based on the Stroop paradigm: Participants were cued to determine either the ink color or color name associated with a word stimulus. In contrast, the paired associates task evaluated participants' memory for either one or four previously memorized pairs of words. On each trial, an instructional cue appeared briefly on the screen, followed by an 8-sec delay and a probe period. The left ventrolateral PFC (VLPFC) and the left supplementary motor area (SMA)/pre-SMA were engaged during the delay period for all conditions, consistent with a general role in rule representation. In contrast, different parts of the dorsolateral PFC, the anterior PFC, and the right VLPFC were preferentially engaged by one or both of the more challenging rules, consistent with the idea that rules are represented by partially distinct brain structures according to their content.
Error and Deviance Processing in Implicit and Explicit Sequence Learning
Authors: Ferdinand Nicola K. , Mecklinger Axel , Kray Jutta
Published: December 2007

In this experiment, we examined the extent to which error-driven learning may operate under implicit learning conditions. We compared error monitoring in a sequence learning task in which stimuli consisted of regular, irregular, or random sequences. Subjects were either informed (explicit condition) or not informed (implicit condition) about the existence of the sequence. For both conditions, reaction times were faster to stimuli from regular sequences than from random sequences, thus supporting the view that sequence learning occurs irrespective of learning condition. Response-locked event-related potentials (ERPs) showed a pronounced ERN/Ne, thereby signaling the detection of committed errors. Deviant stimuli from irregular sequences elicited an N2b component that developed in the course of the experiment, albeit faster for explicit than implicit learners. This observation supports the view that deviant events acquire the status of perceived errors during explicit and implicit learning, and thus, an N2b is generated resembling the ERN/Ne to committed errors. While performing the task, expectations about upcoming events are generated, compared to the actual events, and evaluated on the dimension “better or worse than expected.” The accuracy of this process improves with learning, as shown by a gradual increase in N2b amplitude as a function of learning. Additionally, a P3b, which is thought to mirror conscious processing of deviant stimuli and is related to updating of working memory representations, was found for explicit learners only.
The Functional Effect of Transcranial Magnetic Stimulation: Signal Suppression or Neural Noise Generation?
Authors: Harris Justin A. , Clifford Colin W. G. , Miniussi Carlo
Published: December 2007

Transcranial magnetic stimulation (TMS) is a popular tool for mapping perceptual and cognitive processes in the human brain. It uses a magnetic field to stimulate the brain, modifying ongoing activity in neural tissue under the stimulating coil, producing an effect that has been likened to a “virtual lesion.” However, research into the functional basis of this effect, essential for the interpretation of findings, lags behind its application. Acutely, TMS may disable neuronal function, thereby interrupting ongoing neural processes. Alternatively, the effects of TMS have been attributed to an injection of “neural noise,” consistent with its immediate and effectively random depolarization of neurons. Here we apply an added-noise paradigm to test these alternatives. We delivered TMS to the visual cortex and measured its effect on a simple visual discrimination task, while concurrently manipulating the level of image noise in the visual stimulus itself. TMS increased thresholds overall; and increasing the amount of image noise systematically increased discrimination thresholds. However, these two effects were not independent. Rather, TMS interacted multiplicatively with the image noise, consistent with a reduction in the strength of the visual signal. Indeed, in this paradigm, there was no evidence that TMS independently added noise to the visual process. Thus, our findings indicate that the “virtual lesion” produced by TMS can take the form of a loss of signal strength which may reflect a momentary interruption to ongoing neural processing.
Dissociable Neural Effects of Task Order Control and Task Set Maintenance during Dual-task Processing
Authors: Stelzel Christine , Kraft Antje , Brandt Stephan A. , Schubert Torsten
Published: December 2007

The functional relevance of the lateral prefrontal cortex (lPFC) for the ability to process two tasks simultaneously has been debated extensively in previous studies that employed functional magnetic resonance imaging (fMRI) to investigate the neural correlates of dual-task processing. In the present fMRI study, we shed new light on this debate by directly comparing the lPFC activity changes for two cognitive functions commonly associated with dual-task performance: task order control and task set maintenance. We manipulated both functions in a 2 × 2 integrated parametric design. The fMRI data revealed a functional-neuroanatomical dissociation for the lPFC. Regions surrounding the inferior frontal sulcus and the middle frontal gyrus were exclusively associated with task order control but not with increased demands on task set maintenance during dual-task processing. The only lPFC region associated with task set maintenance was located in the left anterior insula. Outside the lPFC, we found dissociable regions for task order control and task set maintenance bilaterally in the premotor cortices with more rostral premotor activity for task order control and more caudal premotor activity for task set maintenance. In addition, task order control activated the intraparietal sulci bilaterally. Our data clearly suggest that task order control is a separable cognitive mechanism in dual-task situations that is related to activity changes in the lPFC and that can be dissociated from task set maintenance.
The Neural Integration of Speaker and Message
Authors: Van Berkum Jos J. A. , van den Brink Danielle , Tesink Cathelijne M. J. Y. , Kos Miriam , Hagoort Peter
Published: December 2007

When do listeners take into account who the speaker is? We asked people to listen to utterances whose content sometimes did not match inferences based on the identity of the speaker (e.g., “If only I looked like Britney Spears” in a male voice, or “I have a large tattoo on my back” spoken with an upper-class accent). Event-related brain responses revealed that the speaker's identity is taken into account as early as 200–300 msec after the beginning of a spoken word, and is processed by the same early interpretation mechanism that constructs sentence meaning based on just the words. This finding is difficult to reconcile with standard “Gricean” models of sentence interpretation in which comprehenders initially compute a local, context-independent meaning for the sentence (“semantics”) before working out what it really means given the wider communicative context and the particular speaker (“pragmatics”). Because the observed brain response hinges on voice-based and usually stereotype-dependent inferences about the speaker, it also shows that listeners rapidly classify speakers on the basis of their voices and bring the associated social stereotypes to bear on what is being said. According to our event-related potential results, language comprehension takes very rapid account of the social context, and the construction of meaning based on language alone cannot be separated from the social aspects of language use. The linguistic brain relates the message to the speaker immediately.
“Brain Is to Thought as Stomach Is to ??”: Investigating the Role of Rostrolateral Prefrontal Cortex in Relational Reasoning
Authors: Wendelken Carter , Nakhabenko Denis , Donohue Sarah E. , Carter Cameron S. , Bunge Silvia A.
Published: December 2007

Brain imaging studies suggest that the rostrolateral prefrontal cortex (RLPFC), is involved in relational reasoning. Functional magnetic resonance imaging (fMRI) studies involving Raven's Progressive Matrices or verbal propositional analogies indicate that the RLPFC is engaged by tasks that require integration across multiple relational structures. Several studies have shown that the RLPFC is more active when people must evaluate an analogy (e.g., Is shoe to foot as glove is to hand?) than when they must simply evaluate two individual semantic relationships, consistent with the hypothesis that this region is important for relational integration. The current fMRI investigation further explores the role of the RLPFC in reasoning and relational integration by comparing RLPFC activation across four different propositional analogy conditions. Each of the four conditions required either relation completion (e.g., Shoe is to foot as glove is to WHAT? → “hand”) or relation comparison (e.g., Is shoe to foot as glove is to hand? → “yes”). The RLPFC was engaged more strongly by the comparison subtask relative to completion, suggesting that the RLPFC is particularly involved in comparing relational structures.
Bayesian Multidimensional IRT Models With a Hierarchical Structure
Authors: Yanyan Sheng  , Wikle Christopher K.
Published: December 2007

As item response models gain increased popularity in large-scale educational and measurement testing situations, many studies have been conducted on the development and applications of unidimensional and multidimensional models. Recently, attention has been paid to IRT-based models with an overall ability dimension underlying several ability dimensions specific for individual test items, where the focus is mainly on models with dichotomous latent traits. The purpose of this study is to propose such models with continuous latent traits under the Bayesian framework. The proposed models are further compared with the conventional IRT models using Bayesian model choice techniques. The results from simulation studies as well as actual data suggest that (a) such models can be developed; (b) compared with the unidimensional IRT model, the proposed models better describe the actual data; and (c) the use of the proposed IRT models and the multiunidimensional model should be based on different beliefs about the underlying dimensional structure of a test.
Beyond the “Science of Sophomores”
Authors: Bouffard Jeff , Bry Jeff , Smith Shamayne , Bry Rhonda
Published: December 2007

Much of the criminological literature testing rational choice theory has utilized hypothetical scenarios presented to university students. Although this research generally supports rational choice theory, a common criticism is that conclusions from these studies may not generalize to samples of actual offenders. This study proceeds to examine this issue in two steps. First, a traditional sample of university students is examined to determine how various costs and benefits relate to their hypothetical likelihood of offending. Then the same data collection procedures are employed with a somewhat different sample of younger, adjudicated, and institutionalized offenders to determine whether the conclusions drawn from the student sample generalize to this offender sample. Results generally suggest that the content and process of hypothetical criminal decision making differ in the sample of known offenders relative to the university students. Limitations of the current study, as well as suggestions for future research, are discussed.
Study of the Mechanical and Morphological Properties of Plasticized PVC Composites Containing Rice Husk Fillers
Authors: Crespo J.E. , Sánchez L. , García D. , López J.
Published: December 2007

The present study develops new composite materials derived from environmentally friendly material, based on lignocellulosic fillers combined with a thermoplastic matrix. Cellulose fillers are obtained as a by-product of the agri-food industry; specifically rice husk with PVC thermoplastics as a matrix, since lignocellulosic materials such as fillers of composites materials, when used instead of inorganic substances and synthetic fibers, offer more advantages in terms of environmental protection. With a view to identifying the degree of influence of filler amount, plasticizer concentration, and filler particle size on the properties of this new composite, we tested its mechanical properties and analyzed tensile fracture surfaces using scanning electron microscopy (SEM).
Flexural Properties of Polystyrene/Organo-Montmorillonite Masterbatch Composites
Authors: Wen Shyang Chow  , Loo Yok Khim  , Ang Tze Kang
Published: December 2007

In this study, a montmorillonite masterbatch (OMMT-MB) containing polystyrene and organo-montmorillonite was first prepared by extrusion processes. Subsequently, blending of polystyrene (PS) and montmorillonite masterbatch (OMMT-MB) was performed by the direct melt intercalation method using a twin-screw extruder followed by compression molding. The flexural and morphological properties of PS/OMMT-MB were characterized by flexural tests and field-emission scanning electron microscopy (FESEM). The flexural tests were carried out at two different testing speeds, i.e. 5 mm/min and 50 mm/min. The flexural modulus of PS increased significantly with the addition of OMMT. This is due to the reinforcement and stiffness of the OMMT-layered silicates. It is interesting to note that the flexural modulus of PS/OMMT-MB was higher than that of both PS and montmorillonite masterbatch (OMMT-MB). This indicates that the dispersion of OMMT in the PS was better and more homogeneous by using the montmorillonite masterbatch approach.
Transcranial Magnetic Stimulation in Child Neurology: Current and Future Directions
Authors: Frye Richard E. , Rotenberg Alexander , Ousley Molliann , Pascual-Leone Alvaro
Published: December 2007

Transcranial magnetic stimulation (TMS) is a method for focal brain stimulation based on the principle of electromagnetic induction, where small intracranial electric currents are generated by a powerful, rapidly changing extracranial magnetic field. Over the past 2 decades TMS has shown promise in the diagnosis, monitoring, and treatment of neurological and psychiatric disease in adults, but has been used on a more limited basis in children. We reviewed the literature to identify potential diagnostic and therapeutic applications of TMS in child neurology and also its safety in pediatrics. Although TMS has not been associated with any serious side effects in children and appears to be well tolerated, general safety guidelines should be established. The potential for applications of TMS in child neurology and psychiatry is significant. Given its excellent safety profile and possible therapeutic effect, this technique should develop as an important tool in pediatric neurology over the next decade.
Rett Syndrome: Recent Research Progress
Authors: Percy Alan K.
Published: December 2007

Recent progress in our understanding of Rett syndrome has been dramatic. Against the background that the clinical features of Rett syndrome may be reversible, in part or in whole, substantial optimism has emerged regarding possible therapies. As such, it is timely to update recent research progress. This update summarizes research advances during the past 18 to 24 months in terms of clinical and translational research, as well as basic research.
Endoscopic Management of Hydrocephalus in Pediatric Patients: A Review of Indications, Techniques, and Outcomes
Authors: Sandberg David I.
Published: December 2007

Although ventriculoperitoneal shunting remains the treatment of choice for many children with hydrocephalus, advances in endoscopic technology have greatly expanded the treatment options for these patients. For selected patients with obstructive hydrocephalus, endoscopic third ventriculostomy and other endoscopic techniques offer substantial advantages over shunting. As with any surgical procedure, appropriate patient selection is critical to successful outcomes. This article reviews modern endoscopic techniques available to treat hydrocephalus, with a focus on selection criteria and outcomes.
Prevalence and Outcome of Congenital Heart Disease in Patients With Neural Tube Defect
Authors: Koçak Gülendam , Önal Çağatay , Koçak Ayhan , Karakurt Cemşit , Ateş Özkan , Çayli Süleyman R. , Yoloğlu Saim
Published: December 2007

A prospective clinical study was designed to establish the risk factors, the prevalence, and the progress of congenital heart defects in children with neural tube defects. Study included 90 children with a mean age of 13.5 ± 30.4 months. There were 53 (59%) patients with spina bifida occulta and 37 (41%) patients with spina bifida aperta. The overall prevalence of congenital heart disease was 27.8% (40.5% in spina bifida aperta and 18.9% in spina bifida occulta; P = .024). There was no statistically significant difference for maternal age, usage of periconceptional folate, and maternal diabetes between the patient and control groups. The authors conclude that congenital heart defects are more common than reported in neural tube defects, and screening echocardiograms are warranted. This should be kept in mind especially in patients requiring minor or major surgical procedures. Furthermore, routine obstetric examination and therefore the use of periconceptional folic acid during pregnancy is still lacking in our country.
Embedding the Internet in the Lives of College Students
Authors: Ogan Christine L. , Ozakca Muzaffer , Groshek Jacob
Published: December 2007

The Internet is increasingly becoming embedded in the lives of most American citizens. College students constitute a group who have made particularly heavy use of the technology for everything from downloading music to distance education to instant messaging. Researchers know a lot about the uses made of the Internet by this group of people but less about the relationship between their offline activities and online behavior. This study reports the results of a web survey of a group of university undergraduates exploring the nature of both online and offline in five areas—the use of news and information, the discussion of politics, the seeking of health information, the use of blogs, and the downloading of media and software.
Ubiquitous Computing
Authors: Sillence Elizabeth , Briggs Pam
Published: December 2007

The notion of ubiquitous computing (ubicomp) has important implications for health care. Ubicomp scenarios involving the rapid communication of information between interested parties assume that health consumers will be willing to place their trust in agents rather than physicians, but are these assumptions reasonable? This article discusses what is known about the role of trust in health care and ways in which the trust relationship has changed with the impact of new technologies. Differences between the current, predominantly web-based environment and that of ubicomp are highlighted in relation to health care. A key point to note is the move away from consumers making their own trust judgments toward a scenario in which these decisions become the domain of intelligent agents.
An Organizational View of Pervasive Computing
Authors: Karat John , Karat Clare-Marie
Published: December 2007

In their research, the authors find that organizations increasingly collect sensitive electronic information. Currently, they do not have a unified way of defining or implementing privacy or security access control policies for such information. This makes it difficult for the organizations to put in place proper management and control of sensitive information or to verify that required or intended regulations for the use of information are met by the organization. Examinations of privacy policy implementations within organizations have not changed the picture much in the past 20 years. Although there has been considerable attention to the development and posting of privacy policies, these policies are generally vague and lack connections to technology that might implement them. Closing the gap between the high-level policies to which organizations strive to adhere and the low-level actions carried out within their IT systems is an important topic for research and development.
E-Voting in an Ubicomp World
Authors: Little Linda , Storer Tim , Briggs Pam , Duncan Ishbel
Published: December 2007

The advances made in technology have unchained the user from the desktop into interactions where access is anywhere, anytime. In addition, the introduction of ubiquitous computing (ubicomp) will see further changes in how we interact with technology and also socially. Ubicomp evokes a near future in which humans will be surrounded by “always-on,” unobtrusive, interconnected intelligent objects where information is exchanged seamlessly. This seamless exchange of information has vast social implications, in particular the protection and management of personal information. This research project investigates the concepts of trust and privacy issues specifically related to the exchange of e-voting information when using a ubicomp type system.
Enhancing Privacy in Public Spaces Through Crossmodal Displays
Authors: Han Cao  , Olivier Patrick , Jackson Daniel
Published: December 2007

The authors introduce the notion of a crossmodal display as a proposal for enhancing the privacy of public information displays. The selection of appropriate display technology and interaction techniques relies on an understanding of the public—private nature of information and the spaces from which it is accessed. The crossmodal display framework supports multiple users simultaneously accessing information that contains public and personal elements. Crossmodal displays are multiuser interfaces that facilitate the efficient public access of personalized information, while maintaining the anonymity of each user in physical public spaces. Based on psychological theories of crossmodal attention that characterize human capabilities for matching information received through different modalities, the framework takes advantage of public displays and mobile devices through the use of peripheral cues and allows information personalization in public space. Two example systems are presented, in the first individuals access situated ambient displays of directions to destinations, and in the second a structured combination of cues is used to provide access to information board displays. The configuration and implications for privacy of both systems is introduced and analyzed within the wider context of access to public information displays in pervasive computing.