bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Episodic and Working Memory Impairments on Semantic and Cognitive Procedural Learning at Alcohol Treatment Entry
Authors: Pitel Anne Lise , Witkowski Thomas , Vabret François , Guillery‐Girard Bérengère , Desgranges Béatrice , Eustache Francis , Beaunieux Hélène
Published: January 2007

Background: Chronic alcoholism is known to impair the functioning of episodic and working memory, which may consequently reduce the ability to learn complex novel information. Nevertheless, semantic and cognitive procedural learning have not been properly explored at alcohol treatment entry, despite its potential clinical relevance. The goal of the present study was therefore to determine whether alcoholic patients, immediately after the weaning phase, are cognitively able to acquire complex new knowledge, given their episodic and working memory deficits.

Methods: Twenty alcoholic inpatients with episodic memory and working memory deficits at alcohol treatment entry and a control group of 20 healthy subjects underwent a protocol of semantic acquisition and cognitive procedural learning. The semantic learning task consisted of the acquisition of 10 novel concepts, while subjects were administered the Tower of Toronto task to measure cognitive procedural learning.

Results: Analyses showed that although alcoholic subjects were able to acquire the category and features of the semantic concepts, albeit slowly, they presented impaired label learning. In the control group, executive functions and episodic memory predicted semantic learning in the first and second halves of the protocol, respectively. In addition to the cognitive processes involved in the learning strategies invoked by controls, alcoholic subjects seem to attempt to compensate for their impaired cognitive functions, invoking capacities of short‐term passive storage. Regarding cognitive procedural learning, although the patients eventually achieved the same results as the controls, they failed to automate the procedure. Contrary to the control group, the alcoholic groups' learning performance was predicted by controlled cognitive functions throughout the protocol.

Conclusion: At alcohol treatment entry, alcoholic patients with neuropsychological deficits have difficulty acquiring novel semantic and cognitive procedural knowledge. Compared with controls, they seem to use more costly learning strategies, which are nonetheless less efficient. These learning disabilities need to be considered when treatment requiring the acquisition of complex novel information is envisaged.
Energetics of Cerium–Zirconium Substitution in the xCe0.8Y0.2O1.9−(1−x)Zr0.8Y0.2O1.9 System
Authors: Chen Weiqun , Navrotsky Alexandra , Xiong Yue Ping , Yokokawa Harumi
Published: January 2007

Energetics of Ce–Zr substitution in xCe0.8Y0.2O1.9−(1−x)Zr0.8Y0.2O1.9 (0≤x≤1) solid solutions, potential candidates for electrolytes in solid oxide fuel cells, were investigated by high temperature oxide melt drop solution calorimetry. The enthalpies of formation relative to the solid solution end‐members, Ce0.8Y0.2O1.9 and Zr0.8Y0.2O1.9 (ΔHf,ss), are slightly positive. The whole substitution range can be divided into three regimes: a zirconia‐dominated region (0≤x<0.4), where ΔHf,ss increases from 0 to 3.9 kJ/mol; a ceria‐dominated region (0.6<x≤1), where ΔHf,ss remains nearly constant at 0 to 0.7 kJ/mol; and a transitional region (0.4≤x≤0.6), where ΔHf,ss decreases from 3.9 to 0.7 kJ/mol. Such a trend in ΔHf,ss strongly supports a scavenging effect of Zr4+ on oxygen vacancies, i.e. oxygen vacancies prefer the nearest neighboring sites of Zr4+ as in yttria‐stabilized zirconia. The formation enthalpy from binary oxides, fluorite CeO2, monoclinic ZrO2 and C‐type YO1.5, (ΔHf,ox) is also slightly positive, varying analogously to ΔHf,ss.
What Can We Learn from R‐Curve Measurements?
Authors: Munz Dietrich
Published: January 2007

In the last 30 years, crack growth resistance curves (R curves) have been measured and analyzed for many ceramic materials. This body of literature is reviewed critically to address the utility of these measurements. Three effects have been held responsible for the existence of a rising R curve: crack face interaction in the wake of the crack tip, microcracking and crack branching ahead of the tip, and phase transformation ahead of the crack tip. For the crack face interaction, the relation between bridging traction and crack opening displacement characterizes the material behavior. Most experimental investigations have concentrated on specimens with macrocracks and on indentation‐induced cracks. Very few results for R curves starting from natural flaws have been published. From these results, it is concluded that the behavior of specimens with natural flaws cannot be predicted directly from the results of tests with macrocracks and no established framework exists to correlate the two. The analysis of indentation cracks contains many uncertainties and cannot close the gap between macrocracks and natural flaws. The effect of a rising R curve on the strength and on the scatter of the strength is also discussed in the paper.
TRPV1 at nerve endings regulates growth cone morphology and movement through cytoskeleton reorganization
Authors: Goswami C. , Schmidt H. , Hucho F.
Published: January 2007

While the importance of Ca2+ channel activity in axonal path finding is established, the underlying mechanisms are not clear. Here, we show that transient receptor potential vanilloid receptor 1 (TRPV1), a member of the TRP superfamily of nonspecific ion channels, is physically and functionally present at dynamic neuronal extensions, including growth cones. These nonselective cation channels sense exogenous ligands, such as resenifera toxin, and endogenous ligands, such as N‐arachidonoyl‐dopamine (NADA), and affect the integrity of microtubule cytoskeleton. Using TRPV1‐transiently transfected F11 cells and embryonic dorsal root ganglia explants, we show that activation of TRPV1 results in growth cone retraction, and collapse and formation of varicosities along neurites. These changes were due to TRPV1‐activation‐mediated disassembly of microtubules and are partly Ca2+‐independent. Prolonged activation with very low doses (1 nm) of NADA results in shortening of neurites in the majority of isolectin B4‐positive dorsal root ganglia neurones. We postulate that TRPV1 activation plays an inhibitory role in sensory neuronal extension and motility by regulating the disassembly of microtubules. This might have a role in the chronification of pain.
Effects of Stir‐Fry Cooking with Different Edible Oils on the Phytochemical Composition of Broccoli
Authors: Moreno Diego A. , López‐Berenguer Carmen , García‐Viguera Cristina
Published: January 2007

ABSTRACT:  Numerous epidemiological studies indicate that Brassica vegetables in general and broccoli in particular protect humans against cancer; they are rich sources of glucosinolates and posses a high content on flavonoids, vitamins, and mineral nutrients. The contents of total intact glucosinolates, total phenolics, vitamin C, and minerals (potassium, sodium, calcium, magnesium, iron, manganese, zinc, and copper) in the edible portions of freshly harvested broccoli (florets), which was subjected to stir‐frying treatments, were evaluated. In the present work, the stir‐fry cooking experiments were carried out using different edible oils from plant origin (refined olive oil, extra virgin olive oil, sunflower oil, peanut oil, soyabean oil, and safflower oil) known and used worldwide. Results showed that during stir‐frying, phenolics and vitamin C were more affected than glucosinolates and minerals. Stir‐fry cooking with extra virgin olive, soybean, peanut, or safflower oil did not reduce the total glucosinolate content of the cooked broccoli compared with that of the uncooked sample. The vitamin C content of broccoli stir‐fried with extra virgin olive or sunflower oil was similar to that of the uncooked sample, but greater than those samples stir‐fried with other oils.
Secretion of keratinolytic enzymes and keratinolysis byScopulariopsis brevicaulisandTrichophyton mentagrophytes: regression analysis
Authors: Anbu P , Gopinath S C.B , Hilda A , Mathivanan N , Annadurai G
Published: January 2007

A survey on keratinophilic fungi from poultry-farm soils at Namakkal and from feather dumping soils at Chennai, India, revealed the existence of 34 species of fungi. Most of the fungi exhibited variable efficiency in producing extracellular keratinase when grown in plates with chicken feathers as the sole carbon and nitrogen source. The fungi Aspergillus flavus, Aspergillus niger, Aspergillus versicolor, Chrysosporium state of Arthroderma tuberculatum, Paecilomyces carneus, Scopulariopsis brevicaulis, Trichoderma viride, and Trichophyton mentagrophytes were efficient candidates to degrade the feathers. However, when cultivating the strains in submerged conditions in a medium containing chicken feathers as the sole nutrients source, Aspergillus glaucus, Chrysosporium keratinophilum, Curvularia lunata, Fusarium solani, and Penicillium citrinum also proved to be potent. Among all species, S. brevicaulis and Trichophyton mentagrophytes produced higher amounts of keratinase in both methods. Conditions for keratinase production were optimized by statistical design and surface plots. The highest keratinase activity was estimated by S. brevicaulis (3.2 KU/mL) and Trichophyton mentagrophytes (2.7 KU/mL) in the culture medium with chicken feathers and shows (79% and 72.2% of degrading ability, respectively).Key words: keratin, keratinase, keratinophilic fungi, regression analysis, Scopulariopsis brevicaulis, Trichophyton mentagrophytes.
P2 receptor regulation of [Ca2+]iin cultured mouse mesangial cells
Authors: Rivera Ian , Zhang Shali , Fuller B. Scott , Edwards Brentan , Seki Tsugio , Wang Mong-Heng , Marrero Mario B. , Inscho Edward W.
Published: January 2007

Experiments were performed to establish the pharmacological profile of purinoceptors and to identify the signal transduction pathways responsible for increases in intracellular calcium concentration ([Ca2+]i) for cultured mouse mesangial cells. Mouse mesangial cells were loaded with fura 2 and examined using fluorescent spectrophotometry. Basal [Ca2+]iaveraged 102 ± 2 nM ( n = 346). One hundred micromolar concentrations of ATP, ADP, 2′,3′-(benzoyl-4-benzoyl)-ATP (BzATP), ATP-γ-S, and UTP in normal Ca2+medium evoked peak increases in [Ca2+]iof 866 ± 111, 236 ± 18, 316 ± 26, 427 ± 37, and 808 ± 73 nM, respectively. UDP or 2-methylthio-ATP (2MeSATP) failed to elicit significant increases in [Ca2+]i, whereas identical concentrations of adenosine, AMP, and α,β-methylene ATP (α,β-MeATP) had no detectable effect on [Ca2+]i. Removal of Ca2+from the extracellular medium had no significant effect on the peak increase in [Ca2+]iinduced by ATP, ADP, BzATP, ATP-γ-S, or UTP compared with normal Ca2+; however, Ca2+-free conditions did accelerate the rate of decline in [Ca2+]iin cells treated with ATP and UTP. [Ca2+]iwas unaffected by membrane depolarization with 143 mM KCl. Western blot analysis for P2 receptors revealed expression of P2X2, P2X4, P2X7, P2Y2, and P2Y4receptors. No evidence of P2X1and P2X3receptor expression was detected, whereas RT-PCR analysis reveals mRNA expression for P2X1, P2X2, P2X3, P2X4, P2X7, P2Y2, and P2Y4receptors. These data indicate that receptor-specific P2 receptor activation increases [Ca2+]iby stimulating calcium influx from the extracellular medium and through mobilization of Ca2+from intracellular stores in cultured mouse mesangial cells.
Flow-dependent transport in a mathematical model of rat proximal tubule
Authors: Weinstein Alan M. , Weinbaum Sheldon , Duan Yi , Du Zhaopeng , Yan QingShang , Wang Tong
Published: January 2007

The mathematical model of rat proximal tubule has been extended to include calculation of microvillous torque and to incorporate torque-dependent solute transport in a compliant tubule. The torque calculation follows that of Du Z, Yan Q, Duan Y, Weinbaum S, Weinstein AM, and Wang T ( Am J Physiol 290: F289–F296, 2006). In the model calculations, torque-dependent scaling of luminal membrane transporter density [either as an ensemble or just type 3 Na+/H+exchanger (NHE3) alone] had a relatively small impact on overall Na+reabsorption and could produce a lethal derangement of cell volume; coordinated regulation of luminal and peritubular transporters was required to represent the overall impact of luminal flow on Na+reabsorption. When the magnitude of torque-dependent Na+reabsorption in the model agrees with that observed in mouse proximal tubules, the model tubule shows nearly perfect perfusion-absorption balance at high luminal perfusion rates, but enhanced sensitivity of reabsorption at low flow. With a slightly lower coefficient for torque-sensitive transporter insertion, perfusion-absorption balance in the model tubule is closer to observations in the rat over a broader range of inlet flows. In simulation of hyperglycemia, torque-dependent transport attenuated the diuretic effect and brought the model tubule into closer agreement with experimental observation in the rat. The model was also extended to represent finite rates of hydration and dehydration of CO2and H2CO3. With carbonic anhydrase inhibition, torque-dependent transport blunted the diuretic effect and enhanced the shift from paracellular to transcellular NaCl reabsorption. The new features of this model tubule are an important step toward simulation of glomerulotubular balance.
Modulation of Extrasynaptic THIP Conductances by GABAA-Receptor Modulators in Mouse Neocortex
Authors: Drasbek Kim Ryun , Hoestgaard-Jensen Kirsten , Jensen Kimmo
Published: January 2007

THIP is a hypnotic drug, which displays a unique pharmacological profile, because it activates a subset of extrasynaptic γ-aminobutyric acid type A (GABAA) receptors containing δ-subunits. It is important to study the physiology and pharmacology of these extrasynaptic receptors and to determine how THIP interacts with other hypnotics and anesthetics. Here, we study the modulation of the extrasynaptic response to THIP using three classes of GABAA-receptor ligands. In whole cell recordings from mouse neocortical layer 2/3 pyramidal cells, THIP induced an extrasynaptic tonic current of 44 ± 5 pA. The benzodiazepine site agonist and hypnotic zolpidem (500 nM), which displays selectivity for α1/2/3- and γ2-containing receptors, did not alter the tonic current induced by THIP. The anesthetic etomidate (1 μM), which shows selectivity for β2- and β3-containing GABAA receptors, potentiated the THIP current by 126%. Etomidate also induced a small tonic GABAA current per se. The anesthetic propofol (1 μM), which displays broad-spectrum modulatory effects on several GABAA-receptor subtypes, enhanced the tonic THIP current by 117%. Finally, all three compounds modulated the function of intrasynaptic receptors activated by synaptically released GABA. Our study shows that the extrasynaptic GABAA receptors responsible for the tonic THIP conductance likely do not contain α1-, α2-, α3-, and γ2-subunits. Thus the tonic GABAergic conductance in the neocortex is presumably mediated by α4β2/3δ receptors, which are likely to play a major role for neocortical excitability. Furthermore, our study has deepened the knowledge about the cellular actions of THIP as well as THIP's interactions with other hypnotics and anesthetics.
Synapses in the Fly Motion–Vision Pathway: Evidence for a Broad Range of Signal Amplitudes and Dynamics
Authors: Beckers Ulrich , Egelhaaf Martin , Kurtz Rafael
Published: January 2007

Synapses are generally considered to operate efficiently only when their signaling range matches the spectrum of prevailing presynaptic signals in terms of both amplitudes and dynamics. However, the prerequisites for optimally matching the signaling ranges may differ between spike-mediated and graded synaptic transmission. This poses a problem for synapses that convey both graded and spike signals at the same time. We addressed this issue by tracing transmission systematically in vivo in the blowfly's visual-motion pathway by recording from single neurons that receive mixed potential signals consisting of rather slow graded fluctuations superimposed with highly variable spikes from a small number of presynaptic elements. Both pre- and postsynaptic neurons were previously shown to represent preferred-direction motion velocity reliably and linearly at low fluctuation frequencies. To selectively assess the performance of individual synapses and to precisely control presynaptic signals, we voltage clamped one of the presynaptic neurons. Results showed that synapses can effectively convey signals over a much larger amplitude and frequency range than is normally used during graded transmission of visual signals. An explanation for this unexpected finding might lie in the transmission of the spike component that reaches larger amplitudes and contains higher frequencies than graded signals.
Dissociated Representations of Irritation and Valence in Human Primary Olfactory Cortex
Authors: Zelano C. , Montag J. , Johnson B. , Khan R. , Sobel N.
Published: January 2007

Irritation and negative valence are closely associated in perception. However, these perceptual aspects can be dissociated in olfaction where irritation can accompany both pleasant and unpleasant odorants. Whereas the sensation of odor reflects transduction at olfactory receptors, irritation reflects concurrent transduction of the odorant at trigeminal receptors. Thus a stimulus can be either a pure olfactant activating the olfactory receptors only or a bimodal odorant activating both types of receptors. Using event-related functional magnetic resonance imaging and a 2 × 2 experimental design contrasting odorant valence (pleasant/unpleasant) and odorant type (pure olfactant/bimodal) we found activity in piriform cortex to be associated with valence, and not type, of odors. In contrast, activity in the olfactory tubercle was associated with type, and not valence, of odors. Importantly, this was found when perceived intensity was held equal across odorants. These findings suggest that dissociable neural substrates subserve the encoding of irritation and valence in olfaction.
Distinction between Perceptual and Attentional Processing in Working Memory Tasks: A Study of Phase-locked and Induced Oscillatory Brain Dynamics
Authors: Deiber Marie-Pierre , Missonnier Pascal , Bertrand Olivier , Gold Gabriel , Fazio-Costa Lara , Ibañez Vicente , Giannakopoulos Panteleimon
Published: January 2007

Working memory involves the short-term storage and manipulation of information necessary for cognitive performance, including comprehension, learning, reasoning and planning. Although electroencephalogram (EEG) rhythms are modulated during working memory, the temporal relationship of EEG oscillations with the eliciting event has not been well studied. In particular, the dynamics of the neural network supporting memory processes may be best captured in induced oscillations, characterized by a loose temporal link with the stimulus. In order to differentiate induced from evoked functional processes, the present study proposes a time-frequency analysis of the 3 to 30 Hz EEG oscillatory activity in a verbal n-back working memory paradigm. Control tasks were designed to identify oscillatory activity related to stimulus presentation (passive task) and focused attention to the stimulus (detection task). Evoked theta activity (4–8 Hz) phase-locked to the visual stimulus was evidenced in the parieto-occipital region for all tasks. In parallel, induced theta activity was recorded in the frontal region for detection and n-back memory tasks, but not for the passive task, suggesting its dependency on focused attention to the stimulus. Sustained induced oscillatory activity was identified in relation to working memory in the theta and beta (15–25 Hz) frequency bands, larger for the highest memory load. Its late occurrence limited to nonmatched items suggests that it could be related to item retention and active maintenance for further task requirements. Induced theta and beta activities displayed respectively a frontal and parietal topographical distribution, providing further functional information on the fronto-posterior network supporting working memory.
The Neural Substrate of Human Empathy: Effects of Perspective-taking and Cognitive Appraisal
Authors: Lamm Claus , Batson C. Daniel , Decety Jean
Published: January 2007

Whether observation of distress in others leads to empathic concern and altruistic motivation, or to personal distress and egoistic motivation, seems to depend upon the capacity for self-other differentiation and cognitive appraisal. In this experiment, behavioral measures and event-related functional magnetic resonance imaging were used to investigate the effects of perspective-taking and cognitive appraisal while participants observed the facial expression of pain resulting from medical treatment. Video clips showing the faces of patients were presented either with the instruction to imagine the feelings of the patient (“imagine other”) or to imagine oneself to be in the patient's situation (“imagine self”). Cognitive appraisal was manipulated by providing information that the medical treatment had or had not been successful. Behavioral measures demonstrated that perspective-taking and treatment effectiveness instructions affected participants' affective responses to the observed pain. Hemodynamic changes were detected in the insular cortices, anterior medial cingulate cortex (aMCC), amygdala, and in visual areas including the fusiform gyrus. Graded responses related to the perspective-taking instructions were observed in middle insula, aMCC, medial and lateral premotor areas, and selectively in left and right parietal cortices. Treatment effectiveness resulted in signal changes in the perigenual anterior cingulate cortex, in the ventromedial orbito-frontal cortex, in the right lateral middle frontal gyrus, and in the cerebellum. These findings support the view that humans' responses to the pain of others can be modulated by cognitive and motivational processes, which influence whether observing a conspecific in need of help will result in empathic concern, an important instigator for helping behavior.
Activation of Right Inferior Frontal Gyrus during Response Inhibition across Response Modalities
Authors: Chikazoe Junichi , Konishi Seiki , Asari Tomoki , Jimura Koji , Miyashita Yasushi
Published: January 2007

The go/no-go task, which effectively taps the ability to inhibit prepotent response tendency, has consistently activated the lateral prefrontal cortex, particularly the right inferior frontal gyrus (rIFG). On the other hand, rIFG activation has rarely been reported in the antisaccade task, seemingly an oculomotor version of the manual go/no-go task. One possible explanation for the variable IFG activation is the modality difference of the two tasks: The go/no-go task is performed manually, whereas the antisaccade task is performed in the oculomotor modality. Another explanation is that these two tasks have different task structures that require different cognitive processes: The traditional antisaccade task requires (i) configuration of a preparatory set prior to antisaccade execution and (ii) response inhibition at the time of antisaccade execution, whereas the go/no-go task requires heightened response inhibition under a minimal preparatory set. To test these possibilities, the traditional antisaccade task was modified in the present functional magnetic resonance imaging study such that it required heightened response inhibition at the time of antisaccade execution under a minimal preparatory set. Prominent activation related to response inhibition was observed in multiple frontoparietal regions, including the rIFG. Moreover, meta-analyses revealed that the rIFG activation in the present study was observed in the go/no-go tasks but not in the traditional antisaccade task, indicating that the rIFG activation was sensitive to the task structure difference, but not to the response modality difference. These results suggest that the rIFG is part of a network active during response inhibition across different response modalities.
Manipulating the Experienced Onset of Intention after Action Execution
Authors: Lau Hakwan C. , Rogers Robert D. , Passingham Richard E.
Published: January 2007

Using transcranial magnetic stimulation (TMS), we have tested the time needed for the perceived onset of spontaneous motor intention to be fully determined. We found that TMS applied over the presupplementary motor area after the execution of a simple spontaneous action shifted the perceived onset of the motor intention backward in time, and shifted the perceived time of action execution forward in time. The size of the effect was similar regardless of whether TMS was applied immediately after the action or 200 msec after. The results of three control studies suggest that this effect is time-limited, specific to modality, and also specific to the anatomical site of stimulation. We conclude that the perceived onset of intention depends, at least in part, on neural activity that takes place after the execution of action. A model, which is based on the mechanism of cue integration under the presence of noise, is offered to explain the results. The implications for the conscious control of spontaneous actions are discussed.
Illusory Contours Do Not Pass through the “Blind Spot”
Authors: Maertens Marianne , Pollmann Stefan
Published: January 2007

Our visual percepts are not fully determined by the physical stimulus input. That is why we perceive crisp bounding contours even in the absence of luminance-defined borders in visual illusions such as the Kanizsa figure. It is important to understand which neural processes are involved in creating these artificial visual experiences because this might tell us how we perceive coherent objects in natural scenes, which are characterized by mutual overlap. We have already shown using functional magnetic resonance imaging [Maertens, M., & Pollmann, S. fMRI reveals a common neural substrate of illusory and real contours in v1 after perceptual learning. Journal of Cognitive Neuroscience, 17, 1553–1564, 2005] that neurons in the primary visual cortex (V1) respond to these stimuli. Here we provide support for the hypothesis that V1 is obligatory for the discrimination of the curvature of illusory contours. We presented illusory contours across the portion of the visual field corresponding to the physiological “blind spot.” Four observers were extensively trained and asked to discriminate fine curvature differences in these illusory contours. A distinct performance drop (increased errors and response latencies) was observed when illusory contours traversed the blind spot compared to when they were presented in the “normal” contralateral visual field at the same eccentricity. We attribute this specific performance deficit to the failure to build up a representation of the illusory contour in the absence of a cortical representation of the “blind spot” within V1. The current results substantiate the assumption that neural activity in area V1 is closely related to our phenomenal experience of illusory contours in particular, and to the construction of our subjective percepts in general.
Epochal Changes in ENSO–Streamflow Relationships in Sri Lanka
Authors: Zubair Lareef , Chandimala Janaki
Published: January 2007

In an effort to use climate predictions for streamflow and malaria hazard prediction, the decadal variability of the El Niño–Southern Oscillation (ENSO) influence on streamflow and rainfall in the Kelani River in Sri Lanka was investigated based on records from 1925 to 1995. In the last half century, the warm ENSO phase was associated with decreased annual streamflow and the cold ENSO phase with increased streamflow. The annual streamflow had a negative correlation (warm ENSO associated with low streamflow) with the concurrent ENSO index of Niño-3.4 that was significant at the 5% level. This negative correlation with Niño-3.4 is enhanced to a 1% significance level if the aggregate streamflow from January to September alone is considered. There has been a transition in correlation between January–September streamflow and ENSO between the 1950s and 1970s from near or above zero to negative values that have 95% significance levels reminiscent of an epochal shift. This shift was evident when considering the period when the southwest monsoon dominates (April–September) or when correlations were undertaken between the seasonal streamflow and rainfall and the ENSO index in the month prior to each season. Since the relationship between ENSO and Sri Lankan streamflow has strengthened in recent decades the potential for ENSO-based prediction is retained. The epochal shift may also explain why malaria epidemics ceased to co-occur frequently with El Niño episodes after 1945.
Barotropic Instability of a Zonal Jet: From Nondivergent Perturbations on the β Plane to Divergent Perturbations on a Sphere
Authors: Paldor Nathan , Dvorkin Yona
Published: January 2007

The linear instability of divergent perturbations that evolve on a cos2 mean steady zonal jet embedded in a zonal channel on the β plane and on a rotating sphere is studied for zonally propagating wavelike perturbations of the shallow-water equations. The complex phase speeds result from the imposition of the no-flow boundary conditions at the channel walls on the numerical solutions of the linear differential equations for the wave latitude-dependent amplitude. In addition, the same numerical method is applied to the traditional problem of linear instability of nondivergent perturbations on the β plane where results reaffirm the classical, analytically derived, features. For these nondivergent perturbations, the present study shows that the growth rate increases monotonically with the jet maximal speed and that the classical result of a local maximum at some finite westward-directed speed results from scaling the growth rates on the jet’s speed. In contrast to nondivergent perturbations, divergent perturbations on the β plane have no short-wave cutoff, and so the nondivergent solution does not provide an estimate for the divergent solution, even when the ocean is 1000 km deep (i.e., when the speed of gravity waves exceeds 10 Mach). For realistic values of the ocean depth, the growth rates of divergent perturbations are smaller than those of nondivergent perturbations, but with the increase in the ocean depth they become larger than those of nondivergent perturbations. For both perturbations, a slight asymmetry exists between eastward- and westward-flowing jets. The growth rates of divergent perturbations on a sphere are similar to those on the β plane for the same values of the model parameters, but the asymmetry between eastward and westward jets is more conspicuous on a sphere. The value of g′H′ (g′ is the reduced gravity; H′ is the equivalent mean layer thickness), which is filtered out in nondivergent theory, determines for divergent perturbations the relative magnitude of zonal velocity, meridional velocity, and height but has little effect on the growth rates.
Experimental Study of Suppressing PVC Fire with Water Mist using a Cone Calorimeter
Authors: Zhang Yongfeng , Zhu Wei , Zhou Xiaomeng , Qin Jun , Liao Guanxuan
Published: January 2007

Effect of water mist on the small-scale solid fuel PVC (poly vinyl chloride) fire in a confined space has been studied experimentally using a cone calorimeter. In this study, the combustion characteristics of PVC, and the interaction between the water mists and the diffusion flame in a confined space with proper ventilation control are studied under various conditions in the cone calorimeter. The water mist is generated by a single pressure nozzle and the diffusion flame is produced from PVC samples, respectively. The Laser Doppler Velocimetry/Adaptive Phase Doppler Velocimetry LDV/APV system is employed to determine the water mist characteristics. The results of the test showed that the combustion of PVC is a two-step process, the water mist suppress the diffusion flame in a confined space via oxygen displacement, heat extraction, and heat radiant attenuation. Heat extraction (flame cooling and fuel surface cooling) plays a dominant role by suppressing the PVC fire when the water mists of enough volume flux are applied to the diffusion flame in a confined space. The higher the operational pressure, the easier the suppression.
In Situ Compatibilization of the Blends of Low-density Polyethylene (LDPE) and Polydimethylsiloxane (PDMS) Rubber by Ethylene Methyl Acrylate (EMA) Copolymer
Authors: Jana R. N. , Nando G. B.
Published: January 2007

The blends of low-density polyethylene (LDPE) and polydimethylsiloxane (PDMS) rubber have been compatibilized with the help of ethylene methyl acrylate (EMA) copolymer. The optimum levels of EMA, based on the maximum strength properties observed, have been found to be 2, 4, 8, and 10 wt.% for LDPE-PDMS 70/30, 60/40, 40/60, and 30/70 blends, respectively. This has been further confirmed from their dynamic mechanical analysis, adhesion studies, X-ray diffraction studies, and phase morphology. Dynamic mechanical analysis exhibits improved compatibility of the blend constituents with addition of EMA. Adhesion strength (lap shear) improves with addition of EMA in the blends. With the optimum level of EMA a higher degree of crystallinity and finer phase morphology are observed.
Effect of Intermolecular Interactions and Cooling Rates on Crystallization Behaviors of Polyamide 6 Blends
Authors: Zhang Shijie , Huang Xianbo , Zhang Mingqiu , Zhao Jianqing
Published: January 2007

Three types of polyamide 6 based blends are prepared, in which the intermolecular interactions are different, ranging from ‘no interaction’ to strong interaction. Under two extreme cooling conditions, the melts of the blends crystallized and then the crystalline structure and melting behaviors are examined, respectively. The results suggest that depending upon the degree of intermolecular interaction and the amount of the second component, PA6 may have different crystal forms.
Clothing Air Gap Layers and Thermal Protective Performance in Single Layer Garment
Authors: Song Guowen
Published: January 2007

A three-dimensional body scanning technique is used to measure the air gap layer distribution between different-sized protective garments and the body of a manikin used to evaluate garment thermal protective performance. The influence of fabric material and garment size on the manikin skin-clothing air gap layers existing in single layer thermally protective coveralls is analyzed. Protective performance of these garments is evaluated using the Manikin Thermal Protective Clothing Analysis System. Relationships between the burn patterns, measured on a flash fire manikin and measured manikin-garment air gap layers, are examined. The effects of thermally induced shrinkage as a result of flash fire exposure are discussed in comparisons between single layer protective coverall clothing made with heat resistant fabrics. An established numerical model is used to forecast the dimensions of skin-clothing air gap for optimum thermal protection.
BAD-LAMP defines a subset of early endocytic organelles in subpopulations of cortical projection neurons
Authors: David Alexandre , Tiveron Marie-Catherine , Defays Axel , Beclin Christophe , Camosseto Voahirana , Gatti Evelina , Cremer Harold , Pierre Philippe
Published: January 2007

The brain-associated LAMP-like molecule (BAD-LAMP) is a new member of the family of lysosome associated membrane proteins (LAMPs). In contrast to other LAMPs, which show a widespread expression, BAD-LAMP expression in mice is confined to the postnatal brain and therein to neuronal subpopulations in layers II/III and V of the neocortex. Onset of expression strictly parallels cortical synaptogenesis. In cortical neurons, the protein is found in defined clustered vesicles, which accumulate along neurites where it localizes with phosphorylated epitopes of neurofilament H. In primary neurons, BAD-LAMP is endocytosed, but is not found in classical lysosomal/endosomal compartments. Modification of BAD-LAMP by addition of GFP revealed a cryptic lysosomal retention motif, suggesting that the cytoplasmic tail of BAD-LAMP is actively interacting with, or modified by, molecules that promote its sorting away from lysosomes. Analysis of BAD-LAMP endocytosis in transfected HeLa cells provided evidence that the protein recycles to the plasma membrane through a dynamin/AP2-dependent mechanism. Thus, BAD-LAMP is an unconventional LAMP-like molecule and defines a new endocytic compartment in specific subtypes of cortical projection neurons. The striking correlation between the appearance of BAD-LAMP and cortical synatogenesis points towards a physiological role of this vesicular determinant for neuronal function.
Inhibition of de novo ceramide synthesis upregulates phospholipase D and enhances myogenic differentiation
Authors: Mebarek Saïda , Komati Hiba , Naro Fabio , Zeiller Caroline , Alvisi Monica , Lagarde Michel , Prigent Annie-France , Némoz Georges
Published: January 2007

In L6 skeletal myoblasts induced to differentiate by Arg8-vasopressin treatment, a short-lived lowering of ceramide levels was observed, followed by a long-lasting elevation that was prevented by inhibitors of the de novo synthesis pathway, fumonisin B1 and myriocin. Both inhibitors increased the expression of myogenic differentiation markers and cell fusion rate, whereas short-chain ceramides inhibited these responses. Similar drug effects were observed on primary mouse satellite cell differentiation. Furthermore, bacterial sphingomyelinase overexpression suppressed myogenin nuclear accumulation in L6 cells. These data suggested that endogenous ceramide mediates a negative feedback mechanism limiting myogenic differentiation, and that inhibitors of ceramide synthesis promoted myogenesis by removing this control. Phospholipase D (PLD), a recognized target of ceramide, is required for myogenesis, as shown by the negative effects of PLD1 isoform depletion obtained by siRNA treatment. Fumonisin induced an increase in PLD activity of L6 cells, whereas C6-ceramide decreased it. The expression of PLD1 mRNA transcripts was selectively decreased by C6-ceramide, and increased by ceramide synthesis inhibitors. An early step of myogenic response is the PLD1-dependent formation of actin stress fiber-like structures. C6-ceramide addition or overexpression of sphingomyelinase impaired actin fiber formation. Ceramide might thus regulate myogenesis through downregulation of PLD1 expression and activity.
β-arrestin signaling and regulation of transcription
Authors: Ma Lan , Pei Gang
Published: January 2007

β-arrestin 1 and β-arrestin 2 are well-known negative regulators of G-protein-coupled receptor (GPCR) signaling. Upon GPCR activation, β-arrestins translocate to the cell membrane and bind to the agonist-occupied receptors. This uncouples these receptors from G proteins and promotes their internalization, thus causing desensitization. However, accumulating evidence indicates that β-arrestins also function as scaffold proteins that interact with several cytoplasmic proteins and link GPCRs to intracellular signaling pathways such as MAPK cascades. Recent work has also revealed that, in response to activation of certain GPCRs, β-arrestins translocate from the cytoplasm to the nucleus and associate with transcription cofactors such as p300 and cAMP-response element-binding protein (CREB) at the promoters of target genes to promote transcription. They also interact with regulators of transcription factors, such as IκBα and MDM2, in the cytoplasm and regulate transcription indirectly. This β-arrestin-mediated regulation of transcription appears to play important roles in cell growth, apoptosis and modulation of immune functions.
The relationship between beliefs about depression and coping strategies: Gender differences
Authors: Kelly Morgen A. R. , Sereika Susan M. , Battista Deena R. , Brown Charlotte
Published: January 2007

Objective. Leventhal's common‐sense model of illness representation provides a conceptual framework for exploring the relationship between beliefs about depressive illness and use of coping strategies. We explored this relationship among depressed patients both across genders and in terms of gender differences.

Design. Depressed primary care patients prescribed antidepressants provided self‐report measures of beliefs about depression, emotional reaction to depression, beliefs about medications and coping strategies used. Baseline data from a longitudinal study is presented.

Method. Primary data analyses were conducted using canonical correlation analysis, a multivariate statistical method akin to principal component and regression analyses. It allows for parsimonious description of the association between two multivariate sets of variables (in this case, beliefs about depression and coping strategies) by identifying pairs of linear combinations that account for the majority of the between association from the two sets of variables.

Results. The sample consisted of 189 depressed primary care patients (70.4% female). Results indicated that emotional reaction to depression is a major factor in determining coping strategies. Greater emotional reaction to depression was associated with maladaptive coping for men and women, while women showed additional relationships between greater perceived control over depression and more adaptive coping techniques as well as between perception of consequences of depression and problem solving.

Conclusions. The present research provides preliminary evidence that beliefs about depression are related to coping styles. Further, men and women may differ in the way in which their perceptions about depression influence coping styles adopted.
The I–II Loop Controls Plasma Membrane Expression and Gating of Cav3.2 T-Type Ca2+Channels: A Paradigm for Childhood Absence Epilepsy Mutations
Authors: Vitko Iuliia , Bidaud Isabelle , Arias Juan Manuel , Mezghrani Alexandre , Lory Philippe , Perez-Reyes Edward
Published: January 2007

Calcium currents via low-voltage-activated T-type channels mediate burst firing, particularly in thalamic neurons. Considerable evidence supports the hypothesis that overactive T-channels may contribute to thalamocortical dysrhythmia, including absence epilepsy. Single nucleotide polymorphisms in one of the T-channel genes (CACNA1H, which encodes Cav3.2) are associated with childhood absence epilepsy in a Chinese population. Because only a fraction of these polymorphisms are predicted to increase channel activity and neuronal firing, we hypothesized that other channel properties may be affected. Here we describe that all the polymorphisms clustered in the intracellular loop connecting repeats I and II (I–II loop) increase the surface expression of extracellularly tagged Cav3.2 channels. The functional domains within the I–II loop were then mapped by deletion analysis. The first 62 amino acids of the loop (post IS6) are involved in regulating the voltage dependence of channel gating and inactivation. Similarly, the last 15 amino acids of the loop (pre IIS1) are involved in channel inactivation. In contrast, the central region of I–II loop regulates surface expression, with no significant effect on channel biophysics. Electrophysiology, luminometry, fluorescence-activated cell sorting measurements, and confocal microscopy studies demonstrate that deletion of this central region leads to enhanced surface expression of channels from intracellular compartments to the plasma membrane. These results provide novel insights into howCACNA1Hpolymorphisms may contribute to CaV3.2 channel overactivity and consequently to absence epilepsy and establish the I–II loop as an important regulator of CaV3.2 channel function and expression.
A WAVE-1 and WRP Signaling Complex Regulates Spine Density, Synaptic Plasticity, and Memory
Authors: Soderling Scott H. , Guire Eric S. , Kaech Stefanie , White Jon , Zhang Fang , Schutz Kevin , Langeberg Lorene K. , Banker Gary , Raber Jacob , Scott John D.
Published: January 2007

The scaffolding protein WAVE-1 (Wiskott-Aldrich syndrome protein family member 1) directs signals from the GTPase Rac through the Arp2/3 complex to facilitate neuronal actin remodeling. The WAVE-associated GTPase activating protein called WRP is implicated in human mental retardation, and WAVE-1 knock-out mice have altered behavior. Neuronal time-lapse imaging, behavioral analyses, and electrophysiological recordings from genetically modified mice were used to show that WAVE-1 signaling complexes control aspects of neuronal morphogenesis and synaptic plasticity. Gene targeting experiments in mice demonstrate that WRP anchoring to WAVE-1 is a homeostatic mechanism that contributes to neuronal development and the fidelity of synaptic connectivity. This implies that signaling through WAVE-1 complexes is essential for neural plasticity and cognitive behavior.
Reinforcement Learning Signals Predict Future Decisions
Authors: Cohen Michael X , Ranganath Charan
Published: January 2007

Optimal behavior in a competitive world requires the flexibility to adapt decision strategies based on recent outcomes. In the present study, we tested the hypothesis that this flexibility emerges through a reinforcement learning process, in which reward prediction errors are used dynamically to adjust representations of decision options. We recorded event-related brain potentials (ERPs) while subjects played a strategic economic game against a computer opponent to evaluate how neural responses to outcomes related to subsequent decision-making. Analyses of ERP data focused on the feedback-related negativity (FRN), an outcome-locked potential thought to reflect a neural prediction error signal. Consistent with predictions of a computational reinforcement learning model, we found that the magnitude of ERPs after losing to the computer opponent predicted whether subjects would change decision behavior on the subsequent trial. Furthermore, FRNs to decision outcomes were disproportionately larger over the motor cortex contralateral to the response hand that was used to make the decision. These findings provide novel evidence that humans engage a reinforcement learning process to adjust representations of competing decision options.
Direct Astrocytic Contacts Regulate Local Maturation of Dendritic Spines
Authors: Nishida Hideko , Okabe Shigeo
Published: January 2007

Astrocytes contribute on both development and function of synapses, but it remains unclear whether direct astrocytic contacts regulate development of individual synapses. Two-photon time-lapse imaging of astrocytic and dendritic protrusive activity revealed the correlation of astrocytic contacts with both lifetime and morphological maturation of dendritic protrusions. Astrocytic motility was essential in maturation of spines, because its suppression by manipulating Rac1-dependent signaling in astrocytes resulted in induction of longer, filopodia-like dendritic protrusions. Manipulation of ephrin/Eph-dependent neuron–astrocyte signaling suggested involvement of this signaling pathway in astrocyte-dependent stabilization of newly generated dendritic protrusions. Our data support a model in which astrocytic protrusive activity in development acts as a key local regulator for stabilization of individual dendritic protrusions and subsequent maturation into spines.