bluuebunny/crossref_metadata_2025 huggingface dataset:
Mucin 13: Structure, Function, and Potential Roles in Cancer Pathogenesis
Authors: Maher Diane M. , Gupta Brij K. , Nagata Satoshi , Jaggi Meena , Chauhan Subhash C.
Published: March 2011

Mucin 13 (MUC13) is a high-molecular-weight transmembrane glycoprotein that is frequently and aberrantly expressed in a variety of epithelial carcinomas, including gastric, colorectal, and ovarian cancers. On the basis of the high expression of MUC13 in cancer cells as well as recent laboratory findings suggesting a malignant phenotype of MUC13-transfected cell lines, the oncogenic potential of MUC13 has emerged. The various functional domains of MUC13 may confer oncogenic potential to MUC13. For example, the bulky extracellular domain with extensive modification with glycan chains may prevent cell–cell and cell–extracellular matrix binding whereas the cytoplasmic tail containing serine and tyrosine residues for potential phosphorylation may participate in cell signaling. MUC13 exhibits the characteristics suitable as an early marker for cancer screening and presents a promising target for antibody-guided targeted therapy. Mol Cancer Res; 9(5); 531–7. ©2011 AACR.
Uncoupling p53 Functions in Radiation-Induced Intestinal Damage via PUMA and p21
Authors: Leibowitz Brian J. , Qiu Wei , Liu Hongtao , Cheng Tao , Zhang Lin , Yu Jian
Published: March 2011

The role of p53 in tissue protection is not well understood. Loss of p53 blocks apoptosis in the intestinal crypts following irradiation but paradoxically accelerates gastrointestinal (GI) damage and death. PUMA and p21 are the major mediators of p53-dependent apoptosis and cell-cycle checkpoints, respectively. To better understand these two arms of p53 response in radiation-induced GI damage, we compared animal survival, as well as apoptosis, proliferation, cell-cycle progression, DNA damage, and regeneration in the crypts of WT, p53 knockout (KO), PUMA KO, p21 KO, and p21/PUMA double KO (DKO) mice in a whole body irradiation model. Deficiency in p53 or p21 led to shortened survival but accelerated crypt regeneration associated with massive nonapoptotic cell death. Nonapoptotic cell death is characterized by aberrant cell-cycle progression, persistent DNA damage, rampant replication stress, and genome instability. PUMA deficiency alone enhanced survival and crypt regeneration by blocking apoptosis but failed to rescue delayed nonapoptotic crypt death or shortened survival in p21 KO mice. These studies help to better understand p53 functions in tissue injury and regeneration and to potentially improve strategies to protect or mitigate intestinal damage induced by radiation. Mol Cancer Res; 9(5); 616–25. ©2011 AACR.
Protection from Glycine at Low Doses in Ischemia-Reperfusion Injury of the Rat Small Intestine
Authors: Petrat F. , Drowatzky J. , Boengler K. , Finckh B. , Schmitz K.J. , Schulz R. , de Groot H.
Published: March 2011

Background: Glycine at high doses is known to protect the small intestine against ischemia-reperfusion (I/R) injury. Here, we studied whether glycine at low clinically applicable doses has a protective effect. Methods: In series 1, intestinal I/R was induced in male Wistar rats by occlusion (90 min)/reopening (120 min) of the superior mesenteric artery. Glycine was intravenously infused for 30 min before ischemia (pre-ischemic infusion), and once again from 30 min before until 60 min after reperfusion. Total glycine doses applied over the 120-min infusion were 5, 10, 20, and 75 mg glycine/kg. In series 2, pre-ischemic blood plasma glycine concentrations were determined under the conditions of series 1. Results: In series 1, attenuation of I/R injury was comparable at 10, 20, and 75 mg glycine/kg, but less at 5 mg/kg (as indicated by less intestinal hemorrhages and better preserved mean arterial blood pressure, among other signs). In series 2, pre-ischemic blood plasma glycine concentrations increased with increasing glycine doses from 280 to 330, 340, 380, and 680 µM, respectively. Conclusion: These results demonstrate that even at a dose 50 times lower than previously applied – and at only slightly elevated plasma concentrations – glycine provides full protection against I/R injury of the small intestine.
IGF1 Promoter Polymorphism and Cranial Growth in Individuals Born Very Preterm
Authors: Euser Anne M. , Finken Martijn J.J. , Kharagjitsingh Aan V. , Alizadeh Behrooz Z. , Roep Bart O. , Meulenbelt Ingrid , Dekker Friedo W. , Wit Jan M.
Published: March 2011

Background: Major defects in the IGF1 gene are associated with severely reduced cranial and linear growth. The association between IGF1 promoter polymorphisms and growth is uncertain. Aims: To test the effect of the IGF1 192-bp allele on cranial and linear growth and body mass index (BMI) from birth until age 5 years, and on IQ and serum IGF-1 at age 19 years. Methods: In a birth cohort, including 285 individuals born at a gestational age <32 weeks from the Project On Preterm and Small-for-gestational age infants (POPS), cohort anthropometric measurements were analyzed. At age 19 years IGF1 genotype, serum IGF-1 level and IQ were determined. Regression analyses were performed with mixed models. Results: Homozygotes for the 192-bp allele had a slower cranial growth from birth until age 5 years, and a tendency towards less brain sparing and a slower linear growth compared to the other 2 genotype groups. IGF1 genotype was not associated with IQ or BMI development. Head circumference SDS at age 5 years was positively associated with IQ at age 19 years. Conclusion: Homozygosity for the IGF1 192-bp allele is associated with a slower cranial growth from birth until age 5 years in individuals born very preterm.
Long-Term Follow-Up of a Randomized Controlled Trial of Oral Appliance Therapy in Obstructive Sleep Apnea
Authors: Aarab Ghizlane , Lobbezoo Frank , Heymans Martijn W. , Hamburger Hans L. , Naeije Machiel
Published: March 2011

Background: Long-term trials are needed to capture information regarding the persistence of efficacy and loss to follow-up of both mandibular advancement device (MAD) therapy and continuous positive airway pressure (CPAP) therapy. Objectives: The aim of the study was to compare these treatment aspects between MAD and nasal CPAP (nCPAP) in a 1-year follow-up. Methods:Forty-three mild/moderate obstructive sleep apnea patients (52.2 ± 9.6 years) with a mean apnea-hypopnea index (AHI) of 20.8 ± 9.9 events/h were randomly assigned to two parallel groups: MAD (n = 21) and nCPAP (n = 22). Four polysomnographic recordings were obtained: one before treatment, one for the short-term evaluation, and two recordings 6 and 12 months after the short-term evaluation. Excessive daytime sleepiness (EDS) was also evaluated at the polysomnographic recordings. Results: The initially achieved improvements in the AHI remained stable over time within both groups (p = 0.650). In the nCPAP group, the AHI improved 4.1 events/h more than in the MAD group (p = 0.000). The EDS values showed a gradual improvement over time (p = 0.000), and these improvements were similar for both groups (p = 0.367). In the nCPAP group, more patients withdrew from treatment due to side effects than in the MAD group. Conclusions: The absence of significant long-term differences in EDS improvements between the MAD and the nCPAP groups with mild/moderate obstructive sleep apnea may indicate that the larger improvements in AHI values in the nCPAP group are not clinically relevant. Moreover, nCPAP patients may show more problems in accepting their treatment modality than MAD patients.
Percutaneous Absorption in Man: In vitro-in vivo Correlation
Authors: Lehman P.A. , Raney S.G. , Franz T.J.
Published: March 2011

Aims: To examine the existing literature to determine the degree to which percutaneous absorption data obtained using the excised human skin model match those obtained from living man. Methods: The scientific literature was reviewed to collect data on compounds whose percutaneous absorption through human skin had been measured under both in vitro and in vivo conditions. The in vitro-in vivo (IVIV) correlation was evaluated by computing the in vitro/in vivo ratio using total absorption (percent of applied dose) as the metric for comparison. Results: A total of 92 data sets were collected from 30 published studies. The average IVIV ratio across all values was 1.6, though for any single data set there could be a nearly 20-fold difference between the in vitro and in vivo values. In 85% of the cases, however, the difference was less than 3-fold. The correlation was significantly improved when data were excluded from studies in which the protocols for both studies were not fully harmonized. For harmonized data sets the average IVIV ratio was 0.96 and there was a less than 2-fold difference between the in vitro and in vivo results for any one compound, with IVIV ratios ranging from 0.58 to 1.28. The dominant factors leading to exclusion of data were the use of skin from different anatomical sites and vehicles of differing composition. Conclusions: Percutaneous absorption data obtained from the excised human skin model closely approximate those obtained from living man when the two study protocols are appropriately matched.
Effect of Chlorhexidine Pretreatment on the Stability of Salivary Lactobacilli Probiotic in Six- to Twelve-Year-Old Children: A Randomized Controlled Trial
Authors: Aminabadi N.A. , Erfanparast L. , Ebrahimi A. , Oskouei S.G.
Published: March 2011

This study aimed to investigate the efficacy of chlorhexidine mouthwash disinfection on the stability of lactobacilli probiotic. This study involved 105 children in 3 groups. Subjects in group A received chlorhexidine for 2 weeks, subjects of group B received probiotic yogurt containing Lactobacillus rhamnosus GG (LGG) at a concentration of 2 × 108 colony-forming units per gram for 3 weeks, and subjects in group C received chlorhexidine in the same manner as group A and 24 h after cessation, they received probiotic yogurt in the same manner as group B. Salivary Streptococcus mutans (SM) and LGG were counted at baseline, 24 h, 1 week and 5 weeks after each intervention in all groups. The SM count was reduced 24 h after cessation of chlorhexidine in group A (p < 0.001), and was steady for 5 weeks (p < 0.05). In group B, SM counts did not show significant differences 5 weeks after ending the intake of the probiotic (p > 0.05); LGG counts increased (p < 0.001), but were not steady over 5 weeks. In group C, a significant reduction in SM count was recorded, and the reduced count was steady for 5 weeks; a significant increase in LGG counts was registered (p < 0.001), which was steady for 5 weeks. Intergroup comparison showed a significant increase in LGG counts in groups B and C; however, this increase was not steady in group B. Chlorhexidine treatment before probiotic intake induced more stable colonization with LGG strains than probiotic alone.
Enamel Demineralization and Remineralization under Plaque Fluid-Like Conditions: A Quantitative Light-Induced Fluorescence Study
Authors: Lippert F. , Butler A. , Lynch R.J.M.
Published: March 2011

The present study investigated de- and remineralization in enamel lesions under plaque fluid (PF)-like conditions using quantitative light-induced fluorescence (QLF). Preformed lesions were exposed to partially saturated lactic acid solutions, varying in pH and fluoride concentration ([F]) based on a 5 × 3 factorial study design (0/0.1/0.5/1.5/4 ppm F; pH 4.9/5.2/5.5). Average fluorescence loss (ΔF) was monitored for 11 days. Subsequently, lesions were demineralized in a partially saturated acetic acid solution for two 24-hour periods. Data were analyzed using repeated measures analysis of covariance. Lesions exposed to PF at 4 ppm F and pH 5.5 showed not only the most remineralization (ΔΔF = 28.2 ± 14.0%) for all groups after 11 days, but also the most demineralization (ΔΔF = –19.3 ± 13.5%) after subsequent acetic acid exposure. Increased [F] resulted in more remineralization, regardless of pH. Higher pH values resulted in more remineralization. No remineralization was observed in lesions exposed to F-free solutions, regardless of pH. Remineralization was noticeable under the following conditions: pH 4.9 – [F] = 4 ppm, pH 5.2 – [F] ≧ 1.5 ppm, and pH 5.5 – [F] ≧ 0.5 ppm. Overall, [F] had a stronger effect on remineralization than pH. Subsequent demineralization showed that little protection was offered by PF-like solutions, and further demineralization compared with baseline was observed on lesions not remineralized initially. [F] had a stronger effect on net mineral change than pH. The present study has shown that QLF is a valuable tool in studying lesion de- and remineralization under PF-like conditions, where [F] was shown to be more important than pH.
Genomewide Linkage Scan for Diabetic Renal Failure and Albuminuria: The FIND Study
Authors: Igo, Jr. Robert P. , Iyengar Sudha K. , Nicholas Susanne B. , Goddard Katrina A.B. , Langefeld Carl D. , Hanson Robert L. , Duggirala Ravindranath , Divers Jasmin , Abboud Hanna , Adler Sharon G. , Arar Nedal H. , Horvath Amanda , Elston Robert C. , Bowden Donald W. , Guo Xiuqing , Ipp Eli , Kao W.H. Linda , Kimmel Paul L. , Knowler William C. , Meoni Lucy A. , Molineros Julio , Nelson Robert G. , Pahl Madeline V. , Parekh Rulan S. , Rasooly Rebekah S. , Schelling Jeffrey R. , Shah Vallabh O. , Smith Michael W. , Winkler Cheryl A. , Zager Philip G. , Sedor John R. , Freedman Barry I. ,   on behalf of the Family Investigation of Nephropathy and Diabetes Research Group
Published: March 2011

Background: Diabetic nephropathy (DN) is a leading cause of mortality and morbidity in patients with type 1 and type 2 diabetes. The multicenter FIND consortium aims to identify genes for DN and its associated quantitative traits, e.g. the urine albumin:creatinine ratio (ACR). Herein, the results of whole-genome linkage analysis and a sparse association scan for ACR and a dichotomous DN phenotype are reported in diabetic individuals. Methods: A genomewide scan comprising more than 5,500 autosomal single nucleotide polymorphism markers (average spacing of 0.6 cM) was performed on 1,235 nuclear and extended pedigrees (3,972 diabetic participants) ascertained for DN from African-American (AA), American-Indian (AI), European-American (EA) and Mexican-American (MA) populations. Results: Strong evidence for linkage to DN was detected on chromosome 6p (p = 8.0 × 10–5, LOD = 3.09) in EA families as well as suggestive evidence for linkage to chromosome 7p in AI families. Regions on chromosomes 3p in AA, 7q in EA, 16q in AA and 22q in MA displayed suggestive evidence of linkage for urine ACR. The linkage peak on chromosome 22q overlaps the MYH9/APOL1 gene region, previously implicated in AA diabetic and nondiabetic nephropathies. Conclusion: These results strengthen the evidence for previously identified genomic regions and implicate several novel loci potentially involved in the pathogenesis of DN.
Inherited Dysfunction of Sarcoplasmic Reticulum Ca
2+
Handling and Arrhythmogenesis
Authors: Priori Silvia G. , Chen S.R. Wayne
Published: March 2011

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited arrhythmogenic disease occurring in patients with a structurally normal heart: the disease is characterized by life-threatening arrhythmias elicited by stress and emotion. In 2001, the ryanodine receptor was identified as the gene that is linked to CPVT; shortly thereafter, cardiac calsequestrin was implicated in the recessive form of the same disease. It became clear that abnormalities in intracellular Ca
2+
regulation could profoundly disrupt the electrophysiological properties of the heart. In this article, we discuss the molecular basis of the disease and the pathophysiological mechanisms that are impacting clinical diagnosis and management of affected individuals. As of today, the interaction between basic scientists and clinicians to understand CPVT and identify new therapeutic strategies is one of the most compelling examples of the importance of translational research in cardiology.
The CIA Confronts the Tito-Stalin Split, 1948–1951
Authors: Mehta Coleman
Published: March 2011

After relations between the Soviet Union and Yugoslavia broke down in 1948, the U.S. Central Intelligence Agency (CIA) devoted a good deal of attention to Yugoslavia. Initially, however, the Truman administration was reluctant to provide extensive security assistance to the regime of Josip Broz Tito, who until 1948 had been a brutal Stalinist. The outbreak of the Korean War in June 1950 changed the situation. The United States developed much closer political, economic, and military ties with Yugoslavia, and the CIA established a formal agreement of cooperation with the Yugoslav Ministry of State Security, especially on intelligence-sharing and covert operations. U.S. officials were particularly concerned about ensuring that Yugoslavia would be able to defend itself, if necessary, against a Soviet invasion.
Nhân Văn—Giai Phẩm and Vietnamese “Reform Communism” in the 1950s: A Revisionist Interpretation
Authors: Zinoman Peter
Published: March 2011

This article reexamines Nhân Văn–Giai Phẩm (NVGP), a political protest movement led by intellectuals that coalesced in the Democratic Republic of Vietnam in 1956. The article reassesses the development of the movement and the internal composition of its leadership. Through a close reading of the major publications produced by NVGP, the article takes issue with the conventional view, which characterizes the movement as a robust grouping of political dissidents against the party-state. The article shows that NVGP should in fact be seen as a relatively timid strain of the “revisionist” or “reform Communist” movements that emerged throughout the Communist world in the wake of Iosif Stalin's death.
The French Factor in U.S. Foreign Policy during the Nixon-Pompidou Period, 1969–1974
Authors: Trachtenberg Marc
Published: March 2011

President Richard Nixon and his chief foreign policy adviser, Henry Kissinger, sought to build a close relationship with the new French President Georges Pompidou, who had replaced the testy Charles de Gaulle in mid-1969. Initially, Pompidou and his ministers warmly welcomed the new U.S. policy. But by the end of the Nixon-Pompidou period in 1974, U.S.-French relations were in a tailspin. This article explores what went wrong, showing that numerous issues helped to produce a rift in bilateral ties: the new international monetary framework after the demise of the Bretton Woods system, the U.S.-French nuclear weapons relationship in the early 1970s, the “Year of Europe” affair, and U.S.-European tensions after the outbreak of war in the Middle East in October 1973. This period may have been a lost opportunity for lasting improvements in Franco-American relations.
The Origins of Commitment: Truman and West Berlin
Authors: Larson Deborah Welch
Published: March 2011

Until the 1948–1949 Berlin blockade, the United States had not decided whether U.S. forces should remain in West Berlin after the establishment of a West German government. But after the Soviet Union closed off surface routes to West Berlin, the Truman administration embarked on a massive airlift and established a de facto commitment to preserve the western sectors' independence. The U.S. guarantee to West Berlin is difficult to explain from the standpoint of realist theories of foreign policymaking. Realism maintains that leaders should undertake commitments only if adequate power is available and that ends should be commensurate with means. West Berlin was indefensible, and its access routes could be restricted at any time. Only by analyzing the decision-making process from the standpoint of political psychology can scholars determine why U.S. policymakers acted as they did. President Harry Truman played a pivotal role in decision-making in Berlin, and he relied on his own judgment rather than policy analysis. Psychological research on intuitive judgment indicates that people sometimes make important decisions without deliberating when the problem is highly complex and the outcome uncertain—precisely the conditions Truman faced in 1948.
Implicit and Explicit Mechanisms of Word Learning in a Narrative Context: An Event-related Potential Study
Authors: Batterink Laura , Neville Helen
Published: March 2011

The vast majority of word meanings are learned simply by extracting them from context rather than by rote memorization or explicit instruction. Although this skill is remarkable, little is known about the brain mechanisms involved. In the present study, ERPs were recorded as participants read stories in which pseudowords were presented multiple times, embedded in consistent, meaningful contexts (referred to as meaning condition, M+) or inconsistent, meaningless contexts (M−). Word learning was then assessed implicitly using a lexical decision task and explicitly through recall and recognition tasks. Overall, during story reading, M− words elicited a larger N400 than M+ words, suggesting that participants were better able to semantically integrate M+ words than M− words throughout the story. In addition, M+ words whose meanings were subsequently correctly recognized and recalled elicited a more positive ERP in a later time window compared with M+ words whose meanings were incorrectly remembered, consistent with the idea that the late positive component is an index of encoding processes. In the lexical decision task, no behavioral or electrophysiological evidence for implicit priming was found for M+ words. In contrast, during the explicit recognition task, M+ words showed a robust N400 effect. The N400 effect was dependent upon recognition performance, such that only correctly recognized M+ words elicited an N400. This pattern of results provides evidence that the explicit representations of word meanings can develop rapidly, whereas implicit representations may require more extensive exposure or more time to emerge.
Seeing Race: N170 Responses to Race and Their Relation to Automatic Racial Attitudes and Controlled Processing
Authors: Ofan Renana H. , Rubin Nava , Amodio David M.
Published: March 2011

We examined the relation between neural activity reflecting early face perception processes and automatic and controlled responses to race. Participants completed a sequential evaluative priming task, in which two-tone images of Black faces, White faces, and cars appeared as primes, followed by target words categorized as pleasant or unpleasant, while encephalography was recorded. Half of these participants were alerted that the task assessed racial prejudice and could reveal their personal bias (“alerted” condition). To assess face perception processes, the N170 component of the ERP was examined. For all participants, stronger automatic pro-White bias was associated with larger N170 amplitudes to Black than White faces. For participants in the alerted condition only, larger N170 amplitudes to Black versus White faces were also associated with less controlled processing on the word categorization task. These findings suggest that preexisting racial attitudes affect early face processing and that situational factors moderate the link between early face processing and behavior.
Inflexibly Focused under Stress: Acute Psychosocial Stress Increases Shielding of Action Goals at the Expense of Reduced Cognitive Flexibility with Increasing Time Lag to the Stressor
Authors: Plessow Franziska , Fischer Rico , Kirschbaum Clemens , Goschke Thomas
Published: March 2011

Dynamically adjusting the right amount of goal shielding to varying situational demands is associated with the flexibility of cognitive control, typically linked with pFC functioning. Although stress hormones are found to also bind to prefrontal receptors, the link between stress and cognitive control remains elusive. Based on that, we aimed at investigating effects of acute psychosocial stress on dynamic control adjustments. Forty-eight healthy volunteers were exposed to either a well-established stress induction protocol (the Trier Social Stress Test, TSST) or a standardized control situation before a selective attention (Simon) task involving response conflicts. The individual physiological stress response was monitored by analyzing levels of free cortisol and α-amylase activity in saliva samples showing that the TSST reliably induced an increase of endogenous stress hormone levels. Acute stress did not inevitably impair cognitive functioning, however, as stressed participants showed tonically increased goal shielding (to reduce interference) at the expense of decreased cognitive flexibility. Importantly, as a novel finding in humans, stress effects on cognitive functions were not present immediately after the stress experience but developed gradually over time and, therefore, paralleled the time course of the hypothalamus–pituitary–adrenal (HPA) stress response. In addition, the total increase of individual cortisol levels reflecting HPA activity, but not the total changes in α-amylase activity associated with sympathetic activity, was reversely related to the amount of cognitive flexibility in the final block of testing. Our study provides evidence for a stress-induced time-dependent decrease of cognitive flexibility that might be related to changes in cortisol levels.
Theta and Gamma Power Increases and Alpha/Beta Power Decreases with Memory Load in an Attractor Network Model
Authors: Lundqvist Mikael , Herman Pawel , Lansner Anders
Published: March 2011

Changes in oscillatory brain activity are strongly correlated with performance in cognitive tasks and modulations in specific frequency bands are associated with working memory tasks. Mesoscale network models allow the study of oscillations as an emergent feature of neuronal activity. Here we extend a previously developed attractor network model, shown to faithfully reproduce single-cell activity during retention and memory recall, with synaptic augmentation. This enables the network to function as a multi-item working memory by cyclic reactivation of up to six items. The reactivation happens at theta frequency, consistently with recent experimental findings, with increasing theta power for each additional item loaded in the network's memory. Furthermore, each memory reactivation is associated with gamma oscillations. Thus, single-cell spike trains as well as gamma oscillations in local groups are nested in the theta cycle. The network also exhibits an idling rhythm in the alpha/beta band associated with a noncoding global attractor. Put together, the resulting effect is increasing theta and gamma power and decreasing alpha/beta power with growing working memory load, rendering the network mechanisms involved a plausible explanation for this often reported behavior.
Orienting Attention in Time Activates Left Intraparietal Sulcus for Both Perceptual and Motor Task Goals
Authors: Davranche Karen , Nazarian Bruno , Vidal Franck , Coull Jennifer
Published: March 2011

Attention can be directed not only toward a location in space but also to a moment in time (“temporal orienting”). Temporally informative cues allow subjects to predict when an imminent event will occur, thereby speeding responses to that event. In contrast to spatial orienting, temporal orienting preferentially activates left inferior parietal cortex. Yet, left parietal cortex is also implicated in selective motor attention, suggesting its activation during temporal orienting could merely reflect incidental engagement of preparatory motor processes. Using fMRI, we therefore examined whether temporal orienting would still activate left parietal cortex when the cued target required a difficult perceptual discrimination rather than a speeded motor response. Behaviorally, temporal orienting improved accuracy of target identification as well as speed of target detection, demonstrating the general utility of temporal cues. Crucially, temporal orienting selectively activated left inferior parietal cortex for both motor and perceptual versions of the task. Moreover, conjunction analysis formally revealed a region deep in left intraparietal sulcus (IPS) as common to both tasks, thereby identifying it as a core neural substrate for temporal orienting. Despite the context-independent nature of left IPS activation, complementary psychophysiological interaction analysis revealed how the functional connectivity of left IPS changed as a function of task context. Specifically, left IPS activity covaried with premotor activity during motor temporal orienting but with visual extrastriate activity during perceptual temporal orienting, thereby revealing a cooperative network that comprises both temporal orienting and task-specific processing nodes.
Inhibition-related Activation in the Right Inferior Frontal Gyrus in the Absence of Inhibitory Cues
Authors: Lenartowicz Agatha , Verbruggen Frederick , Logan Gordon D. , Poldrack Russell A.
Published: March 2011

The right inferior frontal gyrus (rIFG) has been hypothesized to mediate response inhibition. Typically response inhibition is signaled by an external stop cue, which provides a top–down signal to initiate the process. However, recent behavioral findings suggest that response inhibition can also be triggered automatically by bottom–up processes. In the present study, we evaluated whether rIFG activity would also be observed during automatic inhibition, in which no stop cue was presented and no motor inhibition was actually required. We measured rIFG activation in response to stimuli that were previously associated with stop signals but which required a response on the current trial (reversal trials). The results revealed an increase in rIFG (pars triangularis) activity, suggesting that it can be activated by associations between stimuli and stopping. Moreover, its role in inhibition tasks is not contingent on the presence of an external stop cue. We conclude that rIFG involvement in stopping is consistent with a role in reprogramming of action plans, which may comprise inhibition, and its activity can be triggered through automatic, bottom–up processing.
Comparison of Primate Prefrontal and Premotor Cortex Neuronal Activity during Visual Categorization
Authors: Cromer Jason A. , Roy Jefferson E. , Buschman Timothy J. , Miller Earl K.
Published: March 2011

Previous work has shown that neurons in the PFC show selectivity for learned categorical groupings. In contrast, brain regions lower in the visual hierarchy, such as inferior temporal cortex, do not seem to favor category information over information about physical appearance. However, the role of premotor cortex (PMC) in categorization has not been studied, despite evidence that PMC is strongly engaged by well-learned tasks and reflects learned rules. Here, we directly compare PFC neurons with PMC neurons during visual categorization. Unlike PFC neurons, relatively few PMC neurons distinguished between categories of visual images during a delayed match-to-category task. However, despite the lack of category information in the PMC, more than half of the neurons in both PFC and PMC reflected whether the category of a test image did or did not match the category of a sample image (i.e., had match information). Thus, PFC neurons represented all variables required to solve the cognitive problem, whereas PMC neurons instead represented only the final decision variable that drove the appropriate motor action required to obtain a reward. This dichotomy fits well with PFC's hypothesized role in learning arbitrary information and directing behavior as well as the PMC's role in motor planning.
Axisymmetric Hurricane in a Dry Atmosphere: Theoretical Framework and Numerical Experiments
Authors: Mrowiec Agnieszka A. , Garner Stephen T. , Pauluis Olivier M.
Published: March 2011

This paper discusses the possible existence of hurricanes in an atmosphere without water vapor and analyzes the dynamic and thermodynamic structures of simulated hurricane-like storms in moist and dry environments. It is first shown that the “potential intensity” theory for axisymmetric hurricanes is directly applicable to the maintenance of a balanced vortex sustained by a combination of surface energy and momentum flux, even in the absence of water vapor. This theoretical insight is confirmed by simulations with a high-resolution numerical model. The same model is then used to compare dry and moist hurricanes. While it is found that both types of storms exhibit many similarities and fit well within the theoretical framework, there are several differences, most notably in the storm inflow and in the relationship between hurricane size and intensity. Such differences indicate that while water vapor is not necessary for the maintenance of hurricane-like vortices, moist processes directly affect the structure of these storms.
Vertical Structures of Anvil Clouds of Tropical Mesoscale Convective Systems Observed by CloudSat
Authors: Yuan Jian , Houze Robert A. , Heymsfield Andrew J.
Published: March 2011

A global study of the vertical structures of the clouds of tropical mesoscale convective systems (MCSs) has been carried out with data from the CloudSat Cloud Profiling Radar. Tropical MCSs are found to be dominated by cloud-top heights greater than 10 km. Secondary cloud layers sometimes occur in MCSs, but outside their primary raining cores. The secondary layers have tops at 6–8 and 1–3 km. High-topped clouds extend outward from raining cores of MCSs to form anvil clouds. Closest to the raining cores, the anvils tend to have broader distributions of reflectivity at all levels, with the modal values at higher reflectivity in their lower levels. Portions of anvil clouds far away from the raining core are thin and have narrow frequency distributions of reflectivity at all levels with overall weaker values. This difference likely reflects ice particle fallout and therefore cloud age. Reflectivity histograms of MCS anvil clouds vary little across the tropics, except that (i) in continental MCS anvils, broader distributions of reflectivity occur at the uppermost levels in the portions closest to active raining areas; (ii) the frequency of occurrence of stronger reflectivity in the upper part of anvils decreases faster with increasing distance in continental MCSs; and (iii) narrower-peaked ridges are prominent in reflectivity histograms of thick anvil clouds close to the raining areas of connected MCSs (superclusters). These global results are consistent with observations at ground sites and aircraft data. They present a comprehensive test dataset for models aiming to simulate process-based upper-level cloud structure around the tropics.
On the Linkage between Antarctic Surface Water Stratification and Global Deep-Water Temperature
Authors: Keeling Ralph F. , Visbeck Martin
Published: March 2011

The suggestion is advanced that the remarkably low static stability of Antarctic surface waters may arise from a feedback loop involving global deep-water temperatures. If deep-water temperatures are too warm, this promotes Antarctic convection, thereby strengthening the inflow of Antarctic Bottom Water into the ocean interior and cooling the deep ocean. If deep waters are too cold, this promotes Antarctic stratification allowing the deep ocean to warm because of the input of North Atlantic Deep Water. A steady-state deep-water temperature is achieved such that the Antarctic surface can barely undergo convection. A two-box model is used to illustrate this feedback loop in its simplest expression and to develop basic concepts, such as the bounds on the operation of this loop. The model illustrates the possible dominating influence of Antarctic upwelling rate and Antarctic freshwater balance on global deep-water temperatures.
An Assessment of GCM Skill in Simulating Persistence across Multiple Time Scales
Authors: Johnson Fiona , Westra Seth , Sharma Ashish , Pitman Andrew J.
Published: March 2011

Climate change impact studies for water resource applications, such as the development of projections of reservoir yields or the assessment of likely frequency and amplitude of drought under a future climate, require that the year-to-year persistence in a range of hydrological variables such as catchment average rainfall be properly represented. This persistence is often attributable to low-frequency variability in the global sea surface temperature (SST) field and other large-scale climate variables through a complex sequence of teleconnections. To evaluate the capacity of general circulation models (GCMs) to accurately represent this low-frequency variability, a set of wavelet-based skill measures has been developed to compare GCM performance in representing interannual variability with the observed global SST data, as well as to assess the extent to which this variability is imparted in precipitation and surface pressure anomaly fields. A validation of the derived skill measures is performed using GCM precipitation as an input in a reservoir storage context, with the accuracy of reservoir storage estimates shown to be improved by using GCM outputs that correctly represent the observed low-frequency variability.

Significant differences in the performance of different GCMs is demonstrated, suggesting that judicious selection of models is required if the climate impact assessment is sensitive to low-frequency variability. The two GCMs that were found to exhibit the most appropriate representation of global low-frequency variability for individual variables assessed were the Istituto Nazionale di Geofisica e Vulcanologia (INGV) ECHAM4 and L’Institut Pierre-Simon Laplace Coupled Model, version 4 (IPSL CM4); when considering all three variables, the Max Planck Institute (MPI) ECHAM5 performed well. Importantly, models that represented interannual variability well for SST also performed well for the other two variables, while models that performed poorly for SST also had consistently low skill across the remaining variables.
Vorticity Structures in the Tropical Pacific from a Numerical Simulation
Authors: Ubelmann Clement , Fu Lee-Lueng
Published: March 2011

The small-scale variability of the tropical Pacific is studied with the simulations from a numerical model in terms of vorticity structures. A Lagrangian method based on the Okubo–Weiss parameter is used to identify the structures and track their main characteristics. Between 8°S and 8°N, the structure characteristics are spatially inhomogeneous compared to higher latitudes. They can be grouped into three categories: anticyclonic and cyclonic structures off the equator and the equatorial structures between 2°S and 2°N. They all have a strong annual cycle with maximum presence from September to March, except during strong El Niño years, when the number of structures becomes very low. Off the equator from 2° to 8°, the anticyclonic structures dominate, but with drastically different characteristics north and south of the equator. In the north, large nonlinear vortices develop (known as the tropical instability vortices) in phase with the 30–35-day oscillation related to an unstable first-meridional-mode Rossby waves. In the south, mostly fragmentary linear structures are present, with lower propagation speeds. The equatorial structures are mostly counterclockwise. The larger ones tend to be linear and are clearly associated with Yanai waves. The large majority of the cyclonic structures off the equator are also quite linear and smaller and less numerous than the anticyclonic structures. However, some of them are nonlinear with vorticity values higher than 2 times the Coriolis parameter.
Effect of surface treatment on the post-peak residual strength and toughness of polypropylene/polyethylene-blended fiber-reinforced concrete
Authors: Payrow Pouria , Nokken Michelle R. , Banu Dorina , Feldman Dorel
Published: March 2011

This study involved an experimental investigation into the improvement of mechanical properties of fiber-reinforced concrete (FRC) utilizing chemically treated polypropylene/polyethylene fibers. Four types of chemical surface treatments were examined: two types of chromic acid (Types B and C), potassium permanganate (PP), and hydrogen peroxide solutions. Untreated and treated fibers were added at 0.32% by volume of concrete and also at 0.50% for the best treatment technique. Compressive and flexural strength were measured to quantify improvement. It was found that there were no significant differences in compressive strength. Type B chromic acid solution was found to be the most effective technique in improving the flexural strength of FRC resulting in average increases of 8.9% and 17.6% for peak and residual strengths, respectively, compared to nontreated fibers. While not as effective as plasma treatments, further research may be warranted for chemical treatments. Surface wettability of the treated fibers was measured by contact angle with water. The contact angle was found to have no correlation to the toughness. The higher volume of fibers, both treated and nontreated gave higher residual strength and toughness; however, surface treatment did not significantly enhance mechanical properties.
Effects of fiber loading, fiber type, its mesh sizes, and coupling agent on the properties of oil palm biomass/polypropylene composites
Authors: Ramli R. , Yunus R.M. , Beg M.D.H.
Published: March 2011

This study investigates the effects of fiber type, mesh size, fiber loading, and coupling agent on the performance of oil palm biomass (OPB) fiber composites. The dried OPB fibers were ground and screened into 63, 150, 250, 450, and 500 µm meshes for composite production. Fiber composition and fiber morphology were evaluated by scanning electron microscope (SEM) and energy disperse analysis of X-Ray. Ground fiber was compounded into polypropylene (PP) by means of a twin-screw compounder. Maleated polypropylene (MAPP) was used as a coupling agent during compounding. The incorporated fiber contents for OPB composites were 10%, 20%, 30%, and 40% (by weight). The compounded samples were prepared into test specimens by injection molder. The composites were characterized by tensile testing, flexural testing, impact testing, melt flow index, and SEM. The analysis of variance of the effects of fiber types, fiber mesh sizes, and fiber contents and their interactions on the OPB–PP composite properties were studied and found to affect on composite properties significantly. The most significant effect on strength and modulus was found by the addition of coupling agent which was suggested to be due to the thermodynamic segregation of the MAPP toward the interface resulting in covalent bonding to the −OH groups on the fiber surface.
The adverse effect of transnational and domestic terrorism on growth in Africa
Authors: Gaibulloev Khusrav , Sandler Todd
Published: March 2011

This article investigates the adverse effects of domestic and transnational terrorism on income per capita growth for 51 African countries for 1970–2007, while accounting for cross-sectional (spatial) dependence and conflict (i.e. internal conflicts and external wars). The findings of the fixed-effects panel estimator suggest that transnational terrorism has a significant, but modest, marginal impact on income per capita growth. These results hold for two different terrorism event datasets. However, domestic terrorist events do not affect income per capita growth. Our findings differ from those in an earlier study on the impact of transnational terrorism on African growth, because we uncover a much more moderate effect. In our study, regional impacts and terrorism–conflict interactions effects are also distinguished. Moreover, our sample countries and period are more extensive. Our article contains a host of robustness checks involving macroeconomic and political variables that find virtually identical results. Alternative terrorist variables are also used, with little qualitative change in the findings. The absence of a domestic terrorism impact is surprising because there were many more domestic than transnational terrorist incidents in Africa. To promote growth, host and donor countries must direct scarce counter-terrorism resources to protect against transnational terrorism in particular. The modest impact of transnational terrorism on African growth means that developing countries' economies have been more resilient to terrorism than has been generally thought.
Multiple Auxiliary Variables in Nonresponse Adjustment
Authors: Kreuter Frauke , Olson Kristen
Published: March 2011

Prior work has shown that effective survey nonresponse adjustment variables should be highly correlated with both the propensity to respond to a survey and the survey variables of interest. In practice, propensity models are often used for nonresponse adjustment with multiple auxiliary variables as predictors. These auxiliary variables may be positively or negatively associated with survey participation, they may be correlated with each other, and can have positive or negative relationships with the survey variables. Yet the consequences for nonresponse adjustment of these conditions are not known to survey practitioners. Simulations are used here to examine the effects of multiple auxiliary variables with opposite relationships with survey participation and the survey variables. The results show that bias and mean square error of adjusted respondent means are substantially different when the predictors have relationships of the same directions compared to when they have opposite directions with either propensity or the survey variables. Implications for nonresponse adjustment and responsive designs will be discussed.
Evaluation of turmeric extract on performance indices impressed by induced aflatoxicosis in broiler chickens
Authors: Rangsaz Nader , Ahangaran Majid Gholami
Published: March 2011

The purpose of this study was evaluation of ethanolic turmeric extract (ETE; Curcuma longa) effect on overall performance including body weight (BW), body weight gain (BWG), feed intake and feed conversion ratio (FCR) weekly and cumulative for a period of 4 weeks with 300 commercial broiler chicks (Ross strain). These chicks were randomly divided into four groups with three replicates of 15 chicks in each replicate. In group A, chickens were fed a basal diet, in group B, chickens were fed a basal diet plus 3 ppm productive aflatoxin. In group C, chickens consumed a basal diet plus 0.05% ETE and in group D, chickens received a basal diet with 0.05% ETE plus 3 ppm productive aflatoxin. Aflatoxin production by Aspergillus parasiticus (PTTC NO:1850) in maize was according to the Shotwell method. The results revealed that there were no significant differences in BW, BWG and FCR between groups fed turmeric at 0.05% and the control group. The supplement of ETE in a diet containing 3 ppm aflatoxin can significantly improve performance indices compared with the group that consumed aflatoxin alone. In conclusion, our results suggest that turmeric extract ( Curcuma longa) can provide protection against the negative effects of aflatoxin on performance of broiler chickens.