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Selected AbstractsActin-dependent motility of melanosomes from fish retinal pigment epithelial (RPE) cells investigated using in vitro motility assaysCYTOSKELETON, Issue 2 2004E. L. McNeil Melanosomes (pigment granules) within retinal pigment epithelial (RPE) cells of fish and amphibians undergo massive migrations in response to light conditions to control light flux to the retina. Previous research has shown that melanosome motility within apical projections of dissociated fish RPE cells requires an intact actin cytoskeleton, but the mechanisms and motors involved in melanosome transport in RPE have not been identified. Two in vitro motility assays, the Nitella assay and the sliding filament assay, were used to characterize actin-dependent motor activity of RPE melanosomes. Melanosomes applied to dissected filets of the Characean alga, Nitella, moved along actin cables at a mean rate of 2 ,m/min, similar to the rate of melanosome motility in dissociated, cultured RPE cells. Path lengths of motile melanosomes ranged from 9 to 37 ,m. Melanosome motility in the sliding filament assay was much more variable, ranging from 0.4,33 ,m/min; 70% of velocities ranged from 1,15 ,m/min. Latex beads coated with skeletal muscle myosin II and added to Nitella filets moved in the same direction as RPE melanosomes, indicating that the motility is barbed-end directed. Immunoblotting using antibodies against myosin VIIa and rab27a revealed that both proteins are enriched on melanosome membranes, suggesting that they could play a role in melanosome transport within apical projections of fish RPE. Cell Motil. Cytoskeleton 58:71,82, 2004. © 2004 Wiley-Liss, Inc. [source] Channel sedimentation and erosion of the Jiangsu reach of the Yangtze River during the last 44 yearsEARTH SURFACE PROCESSES AND LANDFORMS, Issue 12 2009Wang Jian Abstract River channel sedimentation in the lower reaches of the Yangtze River can be affected by both changes in sea level and changes in solid discharge from the upper river. To evaluate dynamic changes of sedimentation and erosion in the Jiangsu reach of the Yangtze River (about 330 km in length) from 1959 to 2003, databases were designed and constructed using a digital elevation model (DEM) of channel topography based on the Jiangsu River Relief Map for 1959, 1970, 1985, 1992, and 2003. The results indicated that the main course of the Yangtze River in Jiangsu Province had experienced an obvious switch from sedimentation to erosion status around 1985 because of the decreasing amount of solid load from the upper parts of the river channel after that year. The sedimentation process in the main course of the Jiangsu reach of the Yangtze River demonstrated the propulsive process of ,downstream-ward aggradations.' Between 1985 and 2003, the erosion rate of the lower segment was greater than those of the middle and upper segments; this is probably because both channel flow and tide current had influenced the lower segment. When channel flow combines with tide current in the same direction, channel erosion can be intensified, especially if there is a solid load shortage in the channel. Copyright © 2009 John Wiley & Sons, Ltd. [source] The effect of information and communication technologies on urban structureECONOMIC POLICY, Issue 54 2008Yannis M. Ioannides SUMMARY Cities This paper examines the effects of information and communication technologies (ICT) on urban structure. Improvements in ICT may lead to changes in urban structure, for example, because they reduce the costs of communicating ideas from a distance. Hence, they may weaken local agglomeration forces and thus provide incentives for economic activity to relocate to smaller urban centres. We use international data on city size distributions in different countries and on country-level characteristics to test the effect of ICT. We find robust evidence that increases in the number of telephone lines per capita encourage the spatial dispersion of population in that they lead to a more concentrated distribution of city sizes. So far the evidence on internet usage is more speculative, although it goes in the same direction. We argue that the internet is likely to have similar, or even larger, effects on urban structures once its use has spread more thoroughly through different economies. , Yannis M. Ioannides, Henry G. Overman, Esteban Rossi-Hansberg and Kurt Schmidheiny [source] Twin deficits: squaring theory, evidence and common senseECONOMIC POLICY, Issue 48 2006Giancarlo Corsetti SUMMARY Budget deficits and current accounts OPENNESS AND FISCAL PERSISTENCE Simple accounting suggests that shocks to the government budget move the current account in the same direction, and this ,twin deficits' intuition leads many observers to call for fiscal consolidation in the US as a necessary measure to reduce the large external imbalance of this country. The response of other macroeconomic variables to budget developments, however, has important implications for ,twin deficits' and for this policy prescription. Focusing on the international transmission of fiscal policy shocks via terms of trade changes, we show that the likelihood and magnitude of twin deficits increases with the degree of openness of an economy, and decreases with the persistence of fiscal shocks. We take this insight to the data and investigate the transmission of fiscal shocks in a vector autoregression (VAR) model estimated for Australia, Canada, the UK and the US. We find that in less open countries the external impact of shocks to either government spending or budget deficits is limited, while private investment responds in line with our theoretical prediction. These results suggest that a fiscal retrenchment in the US may have a limited impact on its current external deficit. , Giancarlo Corsetti and Gernot J. Müller [source] Tonically active neurons in the striatum differentiate between delivery and omission of expected reward in a probabilistic task contextEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2009Paul Apicella Abstract Tonically active neurons (TANs) in the primate striatum are responsive to rewarding stimuli and they are thought to be involved in the storage of stimulus,reward associations or habits. However, it is unclear whether these neurons may signal the difference between the prediction of reward and its actual outcome as a possible neuronal correlate of reward prediction errors at the striatal level. To address this question, we studied the activity of TANs from three monkeys trained in a classical conditioning task in which a liquid reward was preceded by a visual stimulus and reward probability was systematically varied between blocks of trials. The monkeys' ability to discriminate the conditions according to probability was assessed by monitoring their mouth movements during the stimulus,reward interval. We found that the typical TAN pause responses to the delivery of reward were markedly enhanced as the probability of reward decreased, whereas responses to the predictive stimulus were somewhat stronger for high reward probability. In addition, TAN responses to the omission of reward consisted of either decreases or increases in activity that became stronger with increasing reward probability. It therefore appears that one group of neurons differentially responded to reward delivery and reward omission with changes in activity into opposite directions, while another group responded in the same direction. These data indicate that only a subset of TANs could detect the extent to which reward occurs differently than predicted, thus contributing to the encoding of positive and negative reward prediction errors that is relevant to reinforcement learning. [source] Concurrent action observation modulates practice-induced motor memory formationEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2008K. Stefan Abstract Motor practice is associated with the formation of elementary motor memories. Here we tested in human subjects the hypothesis that observation of a motor training associated with physical practice will modulate the encoding process of a motor memory relative to physical practice alone. Voluntary thumb motions were practiced (i) alone in a direction opposite to the baseline direction of transcranial magnetic stimulation (TMS)-evoked movements (physical practice, PP) and in combination with observation of synchronous movements that were either (ii) directionally congruent (same direction, PP + AOc) or (iii) non-congruent (opposite direction, PP + AOnc) to the practiced ones. We evaluated the following measures of motor memory formation: percentage of TMS-evoked thumb movements falling in the direction of practiced motions, acceleration of TMS-evoked movements along the principal movement axis and corticomuscular excitability of training muscles as indexed by motor-evoked potential amplitudes. Both PP and PP + AOc, but not PP + AOnc, significantly increased the percentage of TMS-evoked movements falling in the practiced direction, changed the compound acceleration vector into the trained direction and enhanced the motor-evoked potential amplitudes in the training agonist muscle. The percentage of TMS-evoked movements falling in the practiced direction increased significantly more after PP + AOc than after PP. Across all measures of motor memory formation, PP + AOc was most efficacious, followed by PP and PP + AOnc. Action observation modulates practice effects on formation of a motor memory. Strengthening of the process of motor memory encoding depends on the directional congruency of the observed model. [source] Independent on-line control of the two hands during bimanual reachingEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2004Jörn Diedrichsen Abstract Many studies on bimanual coordination have shown that people exhibit a preference for mirror-symmetric movements. We demonstrate that this constraint is absent when bimanual reaching movements are made to visual targets. We investigated the ability of humans to make on-line adjustments during such movements when one or both targets were displaced during the initial phase of the movements. Adjustments were as efficient during bimanual as unimanual movements, even when two adjustments had to be made simultaneously. When one target was displaced in the bimanual condition, the hand reaching to that target adjusted efficiently to the displacement. However, a small transient perturbation in the trajectory of the other hand was also observed. This perturbation was in the same direction as the displacement, rather than in mirror-symmetric direction. A control experiment demonstrated that these perturbations could be elicited by visual information alone, but that they were also influenced by whether an adjustment was required in the trajectory of the other hand. Our results demonstrate near independent control of the two arms during visually guided reaching. The subtle interference observed between the arms reflects interactions between target-related representations in visual coordinates rather than between movement-related representations in joint- or muscle-coordinates. [source] The conditional party mandate: A model for the study of mass and elite opinion patternsEUROPEAN JOURNAL OF POLITICAL RESEARCH, Issue 3 2007HENRY VALEN What is the level of issue congruence between voters and elected leaders? The article introduces two ideas for the analysis of mass and elite opinion patterns. First, the authors challenge the unidimensional conception of mass-elite linkages, and argue that the opinion structure of political parties may best be understood in the context of a multidimensional policy space. Second, they contest the proximity logic of the traditional party mandate model. In so doing, they propose the ,conditional party mandate model', arguing that ,direction' rather than ,proximity' attracts voters' interest and attention. The authors contend that in issues of principle significance for a particular party (so-called ,core issues'), the party's voters and representatives will proceed in the same direction, but the representatives will stress their position more strongly than the voters. In issues that are less significant to the parties, the relationship between the two levels will be fortuitous and less clear. The analyses, which are based on elite and mass survey data from the Norwegian political system, support the authors' hypotheses concerning positional issues. When the direction of an issue is given, representatives are more extreme than voters. [source] THE EVOLUTION OF WING COLOR: MALE MATE CHOICE OPPOSES ADAPTIVE WING COLOR DIVERGENCE IN COLIAS BUTTERFLIESEVOLUTION, Issue 5 2003Jacintha Ellers Abstract Correlated evolution of mate signals and mate preference may be constrained if selection pressures acting on mate preference differ from those acting on mate signals. In particular, opposing selection pressures may act on mate preference and signals when traits have sexual as well as nonsexual functions. In the butterfly Colias philodice eriphyle, divergent selection on wing color across an elevational gradient in response to the thermal environment has led to increasing wing melanization at higher elevations. Wing color is also a long-range signal used by males in mate searching. We conducted experiments to test whether sexual selection on wing melanization via male mate choice acts in the same direction as natural selection on mate signals due to the thermal environment. We performed controlled mate choice experiments in the field over an elevational range of 1500 meters using decoy butterflies with different melanization levels. Also, we obtained a more direct estimate of the relation between wing color and sexual selection by measuring mating success in wild-caught females. Both our experiments showed that wing melanization is an important determinant of female mating success in C. p. eriphyle. However, a lack of elevational variation in male mate preference prevents coevolution of mate signals and mate preference, as males at all elevations prefer less-melanized females. We suggest that this apparently maladaptive mate choice may be maintained by differences in detectability between the morphs or by preservation of species recognition. [source] PLASTICITY TO LIGHT CUES AND RESOURCES IN ARABIDOPSIS THALIANA: TESTING FOR ADAPTIVE VALUE AND COSTSEVOLUTION, Issue 6 2000Lisa A. Dorn Abstract Plants shaded by neighbors or overhead foliage experience both a reduction in the ratio of red to far red light (R:FR), a specific cue perceived by phytochrome, and reduced photosynthetically active radiation (PAR), an essential resource. We tested the adaptive value of plasticity to crowding and to the cue and resource components of foliage shade in the annual plant Arabidopsis thaliana by exposing 36 inbred families from four natural populations to four experimental treatments: (1) high density, full sun; (2) low density, full sun; (3) low density, neutral shade; and (4) low density, low R:FR-simulated foliage shade. Genotypic selection analysis within each treatment revealed strong environmental differences in selection on plastic life-history traits. We used specific contrasts to measure plasticity to density and foliage shade, to partition responses to foliage shade into phytochrome-mediated responses to the R:FR cue and responses to PAR, and to test whether plasticity was adaptive (i.e., in the same direction as selection in each environment). Contrary to expectation, we found no evidence for adaptive plasticity to density. However, we observed both adaptive and maladaptive responses to foliage shade. In general, phytochrome-mediated plasticity to the R:FR cue of foliage shade was adaptive and counteracted maladaptive growth responses to reduced PAR. These results support the prediction that active developmental responses to environmental cues are more likely to be adaptive than are passive resource-mediated responses. Multiple regression analysis detected a few costs of adaptive plasticity and adaptive homeostasis, but such costs were infrequent and their expression depended on the environment. Thus, costs of plasticity may occasionally constrain the evolution of adaptive responses to foliage shade in Arabidopsis, but this constraint may differ among environments and is far from ubiquitous. [source] Remote myocardium gene expression after 30 and 120 min of ischaemia in the ratEXPERIMENTAL PHYSIOLOGY, Issue 2 2006Miguel S. Guerra The aim of the present study was to investigate how early the onset of ischaemia-induced changes in gene expression is in remote myocardium, and whether these changes would be different for left and right ventricles. Wistar rats (n= 27) were randomly assigned to left coronary artery (LCA) ligation for 30 or 120 min and sham groups. Evans Blue infusion revealed antero-apical left ventricle (LV) and left intraventricular (IV) septal ischaemia (35.5 ± 0.6% of LV mass). LCA ligation induced transient LV systolic dysfunction and sustained biventricular slowing of relaxation. Regarding mRNA levels, type B natriuretic peptide (BNP) was upregulated in the LV at 30 (+370 ± 191%) and 120 min (+221 ± 112%), whilst in the right ventricle (RV) this was only significant at 120 min (+128 ± 39%). Hipoxia-inducible factor 1, and interleukin 6 overexpression positively correlated with BNP. Inducible NO synthase upregulation was present in both ventricles at 120 min (LV, +327 ± 195%; RV, +311 ± 122%), but only in the RV at 30 min (+256 ± 88%). Insulin-like growth factor 1 increased in both ventricles at 30 (RV, +59 ± 18%; LV, +567 ± 192%) and 120 min (RV, +69 ± 33%; LV, +120 ± 24%). Prepro-endothelin-1 was upregulated in the RV at 120 min (+77 ± 25%). Ca2+ -handling proteins were selectively changed in the LV at 120 min (sarcoplasmic reticulum Ca2+ ATPase, 53 ± 7%; phospholamban, +31 ± 4%; Na+,Ca2+ exchanger, 31 ± 6%), while Na+,H+ exchanger was altered only in the RV (,79 ± 5%, 30 min; +155 ± 70%, 120 min). Tumour necrosis factor-, and angiotensin converting enzyme were not significantly altered. A very rapid modulation of remote myocardium gene expression takes place during myocardial ischaemia, involving not only the LV but also the RV. These changes are different in the two ventricles and in the same direction as those observed in heart failure. [source] Interaction equations for multiaxial fatigue assessment of welded structuresFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 11 2004M. BÄCKSTRÖM ABSTRACT Multiaxial fatigue data from 233 welded test specimens taken from eight different studies have been evaluated based on three published interaction equations for normal and shear stress. The interaction equations were obtained from SFS 2378, Eurocode 3 and International Institute of Welding (IIW) recommendations. Fatigue classes for normal and shear stress were obtained directly from the design guidance documents. Additionally, mean fatigue strengths were determined by regression analysis of bending only and torsion only data for different specimen types. In some cases, the S,N slopes assumed by the different standards were not appropriate for the test data. Specimens that showed significantly different cracking locations or cracking mode between bending and torsion were not easily correlated by the interaction equations. Interaction equations work best in cases where both the normal stress and the shear stress tend to produce crack initiation and growth in the same location and in the same direction. The use of a damage summation of 0.5 for non-proportional loading as recommended by IIW was consistent with experimental observations for tube-to-plate specimens. Other codes used a damage sum of unity. [source] Solution structure of a hydrophobic analogue of the winter flounder antifreeze proteinFEBS JOURNAL, Issue 4 2002Edvards Liepinsh The solution structure of a synthetic mutant type I antifreeze protein (AFP I) was determined in aqueous solution at pH 7.0 using nuclear magnetic resonance (NMR) spectroscopy. The mutations comprised the replacement of the four Thr residues by Val and the introduction of two additional Lys-Glu salt bridges. The antifreeze activity of this mutant peptide, VVVV2KE, has been previously shown to be similar to that of the wild type protein, HPLC6 (defined here as TTTT). The solution structure reveals an ,,helix bent in the same direction as the more bent conformer of the published crystal structure of TTTT, while the side chain ,1 rotamers of VVVV2KE are similar to those of the straighter conformer in the crystal of TTTT. The Val side chains of VVVV2KE assume the same orientations as the Thr side chains of TTTT, confirming the conservative nature of this mutation. The combined data suggest that AFP I undergoes an equilibrium between straight and bent helices in solution, combined with independent equilibria between different side chain rotamers for some of the amino acid residues. The present study presents the first complete sequence-specific resonance assignments and the first complete solution structure determination by NMR of any AFP I protein. [source] Tissue Oxygenation Does Not Predict Central Venous Oxygenation in Emergency Department Patients With Severe Sepsis and Septic ShockACADEMIC EMERGENCY MEDICINE, Issue 4 2010Anthony M. Napoli MD Abstract Objectives:, This study sought to determine whether tissue oxygenation (StO2) could be used as a surrogate for central venous oxygenation (ScVO2) in early goal-directed therapy (EGDT). Methods:, The study enrolled a prospective convenience sample of patients aged ,18 years with sepsis and systolic blood pressure <90 mm Hg after 2 L of normal saline or lactate >4 mmol, who received a continuous central venous oximetry catheter. StO2 and ScVO2 were measured at 15-minute intervals. Data were analyzed using a random coefficients model, correlations, and Bland-Altman plots. Results:, There were 284 measurements in 40 patients. While a statistically significant relationship existed between StO2 and ScVO2 (F(1,37) = 10.23, p = 0.002), StO2 appears to systematically overestimate at lower ScVO2 and underestimate at higher ScVO2. This was reflected in the fixed effect slope of 0.49 (95% confidence interval [CI] = 0.266 to 0.720) and intercept of 34 (95% CI = 14.681 to 50.830), which were significantly different from 1 and 0, respectively. The initial point correlation (r = 0.5) was fair, but there was poor overall agreement (bias = 4.3, limits of agreement = ,20.8 to 29.4). Conclusions:, Correlation between StO2 and ScVO2 was fair. The two measures trend in the same direction, but clinical use of StO2 in lieu of ScVO2 is unsubstantiated due to large and systematic biases. However, these biases may reflect real physiologic states. Further research may investigate if these measures could be used in concert as prognostic indicators. ACADEMIC EMERGENCY MEDICINE 2010; 17:349,352 © 2010 by the Society for Academic Emergency Medicine [source] Asymptotic tests of association with multiple SNPs in linkage disequilibriumGENETIC EPIDEMIOLOGY, Issue 6 2009Wei Pan Abstract We consider detecting associations between a trait and multiple single nucleotide polymorphisms (SNPs) in linkage disequilibrium (LD). To maximize the use of information contained in multiple SNPs while minimizing the cost of large degrees of freedom (DF) in testing multiple parameters, we first theoretically explore the sum test derived under a working assumption of a common association strength between the trait and each SNP, testing on the corresponding parameter with only one DF. Under the scenarios that the association strengths between the trait and the SNPs are close to each other (and in the same direction), as considered by Wang and Elston [Am. J. Hum. Genet. [2007] 80:353,360], we show with simulated data that the sum test was powerful as compared to several existing tests; otherwise, the sum test might have much reduced power. To overcome the limitation of the sum test, based on our theoretical analysis of the sum test, we propose five new tests that are closely related to each other and are shown to consistently perform similarly well across a wide range of scenarios. We point out the close connection of the proposed tests to the Goeman test. Furthermore, we derive the asymptotic distributions of the proposed tests so that P -values can be easily calculated, in contrast to the use of computationally demanding permutations or simulations for the Goeman test. A distinguishing feature of the five new tests is their use of a diagonal working covariance matrix, rather than a full covariance matrix as used in the usual Wald or score test. We recommend the routine use of two of the new tests, along with several other tests, to detect disease associations with multiple linked SNPs. Genet. Epidemiol. 33:497,507, 2009. © 2009 Wiley-Liss, Inc. [source] Climate change affects colonization dynamics in a metacommunity of three Daphnia speciesGLOBAL CHANGE BIOLOGY, Issue 6 2008FLORIAN ALTERMATT Abstract Climate change is expected to alter the range and abundance of many species by influencing habitat qualities. For species living in fragmented populations, not only the quality of the present patches but also access to new habitat patches may be affected. Here, we show that colonization in a metacommunity can be directly influenced by weather changes, and that these observed weather changes are consistent with global climate change models. Using a long-term dataset from a rock pool metacommunity of the three species Daphnia magna, Daphnia longispina and Daphnia pulex with 507 monitored habitat patches, we correlated a four-fold increase in colonization rate with warmer, drier weather for the period from 1982 to 2006. The higher colonization rate after warm and dry summers led to an increase in metacommunity dynamics over time. A mechanistic explanation for the increased colonization rate is that the resting stages have a higher exposure to animal and wind dispersal in desiccated rock pools. Although colonization rates reacted in the same direction in all three species, there were significant species-specific effects that resulted in an overall change in the metacommunity composition. Increased local instability and colonization dynamics may even lead to higher global stability of the metacommunity. Thus, whereas climate change has been reported to cause a unidirectional change in species range for many other species, it changes the dynamics and composition of an entire community in this metacommunity, with winners and losers difficult to predict. [source] Variable sensitivity of plant communities in Iceland to experimental warmingGLOBAL CHANGE BIOLOGY, Issue 4 2005Ingibjörg S. Jónsdóttir Abstract Facing an increased threat of rapid climate change in cold-climate regions, it is important to understand the sensitivity of plant communities both in terms of degree and direction of community change. We studied responses to 3,5 years of moderate experimental warming by open-top chambers in two widespread but contrasting tundra communities in Iceland. In a species-poor and nutrient-deficient moss heath, dominated by Racomitrium lanuginosum, mean daily air temperatures at surface were 1,2°C higher in the warmed plots than the controls whereas soil temperatures tended to be lower in the warmed plots throughout the season. In a species-rich dwarf shrub heath on relatively rich soils at a cooler site, dominated by Betula nana and R. lanuginosum, temperature changes were in the same direction although more moderate. In the moss heath, there were no detectable community changes while significant changes were detected in the dwarf shrub heath: the abundance of deciduous and evergreen dwarf shrubs significantly increased (>50%), bryophytes decreased (18%) and canopy height increased (100%). Contrary to some other studies of tundra communities, we detected no changes in species richness or other diversity measures in either community and the abundance of lichens did not change. It is concluded that the sensitivity of Icelandic tundra communities to climate warming varies greatly depending on initial conditions in terms of species diversity, dominant species, soil and climatic conditions as well as land-use history. [source] Marine range shifts and species introductions: comparative spread rates and community impactsGLOBAL ECOLOGY, Issue 3 2010Cascade J. B. Sorte ABSTRACT Aim, Shifts in species ranges are a predicted and realized effect of global climate change; however, few studies have addressed the rates and consequence of such shifts, particularly in marine systems. Given ecological similarities between shifting and introduced species, we examined how our understanding of range shifts may be informed by the more established study of non-native species introductions. Location, Marine systems world-wide. Methods, Database and citation searches were used to identify 129 marine species experiencing range shifts and to determine spread rates and impacts on recipient communities. Analyses of spread rates were based on studies for which post-establishment spread was reported in linear distance. The sizes of the effects of community impacts of shifting species were compared with those of functionally similar introduced species having ecologically similar impacts. Results, Our review and meta-analyses revealed that: (1) 75% of the range shifts found through the database search were in the poleward direction, consistent with climate change scenarios, (2) spread rates of range shifts were lower than those of introductions, (3) shifting species spread over an order of magnitude faster in marine than in terrestrial systems, and (4) directions of community effects were largely negative and magnitudes were often similar for shifters and introduced species; however, this comparison was limited by few data for range-shifting species. Main conclusions, Although marine range shifts are likely to proceed more slowly than marine introductions, the community-level effects could be as great, and in the same direction, as those of introduced species. Because it is well-established that introduced species are a primary threat to global biodiversity, it follows that, just like introductions, range shifts have the potential to seriously affect biological systems. In addition, given that ranges shift faster in marine than terrestrial environments, marine communities might be affected faster than terrestrial ones as species shift with climate change. Regardless of habitat, consideration of range shifts in the context of invasion biology can improve our understanding of what to expect from climate change-driven shifts as well as provide tools for formal assessment of risks to community structure and function. [source] Heat and fluid flow characteristics inside differentially heated square enclosures with single and multiple sliding wallsHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 7 2009E.M. Wahba Abstract Fluid flow and heat transfer characteristics of differentially heated lid driven cavities are numerically modeled and analyzed in the present study. One-, two-, and four-sided lid driven cavity configurations are considered with the vertical walls being maintained at different temperatures and the horizontal walls being thermally insulated. Eight different cavity configurations are considered depending on the direction of wall motion. The Prandtl number Pr is taken to be 0.7, the Grashof number is taken to be 104, while two values for the Richardson number Ri are considered, 0.1 and 10. It is found that both the Richardson number and the cavity configuration affect the heat and fluid flow characteristics in the cavity. It is concluded that for Ri=0.1, a four-sided driven cavity configuration with all walls rotating in the same direction would triple the value of the average Nusselt number at the cold wall when compared to a one-sided driven cavity configuration. However, for Ri=10, the cavity configuration has minimal effect and all eight cases result in an average Nusselt number value at the cold wall ranging between 1.3 and 1.9. © 2009 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/htj.20264 [source] Hemodynamic and Volume Changes during HemodialysisHEMODIALYSIS INTERNATIONAL, Issue 3 2003Robert M. Lindsay Background:,Volume overload is a factor in the hypertension of hemodialysis (HD) patients. Fluid removal is therefore integral to the hemodialysis treatment. Fluid removal by hemodialysis ultrafiltration (UF) may cause intradialytic hypotension and leg cramps. Understanding blood pressure (BP) and volume changes during UF may eliminate intradialytic hypotension and cramps. Studies (S1, S2, and S3) were carried out to determine the amount and direction of changes in body fluid compartments following UF and to determine the relationships between BP, changes in blood volume (,BV), central blood volume (CBV), cardiac output (CO), peripheral vascular resistance (PVR) plus total body water (TBW), and intra- and extracellular fluid volumes (ICF, ECF) in both the whole body and body segments (arms, legs, trunk). Methods:,Indicator dilution technology (Transonic) was used for CBV, CO, and PVR; hematocrit monitoring (Crit-Line) was used for ,BV segmental bioimpedance (Xitron) for TBW, ICF, and ECF. Results:,S1 (n = 21) showed UF sufficient to cause ,BV of ,7% and lead to minor changes (same direction) in CBV and CO, and with cessation of UF, vascular refilling was preferential to CBV. S2 (n = 20) showed that predialysis HD patients are ECF-expanded (ECF/ICF ratio = 0.96, controls = 0.74 [P < 0.0001]) and BP correlates with ECF (r = 0.47, P = 0.35). UF to cause ,BV of ,7% was associated with a decrease in ECF (P < 0.0001) and BP directly (r = 0.46, P = 0.04) plus ,BV indirectly (r = ,0.5, P = 0.024) correlated with PVR, while CBV and CO were maintained. S3 (n = 11) showed that following UF, total-body ECF changes were correlated with leg ECF (r = 0.94) and arm ECF (r = 0.72) but not trunk ECF. Absolute ECF reduction was greatest from the legs. Conclusions:,Predialysis ECF influences BP and UF reduces ,BV and ECF, but CBV and BP are conserved by increasing PVR. ECF reduction is mainly from the legs, hence may cause cramps. Intradialytic hypotension is caused by failure of PVR response. [source] Differential parametric modulation of self-relatedness and emotions in different brain regionsHUMAN BRAIN MAPPING, Issue 2 2009Georg Northoff Abstract Our sense of self is strongly colored by emotions although at the same time we are well able to distinguish affect and self. Using functional magnetic resonance imaging, we here tested for the differential effects of self-relatedness and emotion dimensions (valence, intensity) on parametric modulation of neural activity during perception of emotional stimuli. We observed opposite parametric modulation of self-relatedness and emotion dimensions in the dorsomedial prefrontal cortex and the ventral striatum/nucleus accumbens, whereas neural activity in subcortical regions (tectum, right amygdala, hypothalamus) was modulated by self-relatedness and emotion dimensions in the same direction. In sum, our results demonstrate that self-relatedness is closely linked to emotion dimensions of valence and intensity in many lower subcortical brain regions involved in basic emotional systems and, at the same time, distinct from them in higher cortical regions that mediate cognitive processes necessary for becoming aware of one's self, for example self-consciousness. Hum Brain Mapp, 2009. © 2007 Wiley-Liss, Inc. [source] On the orbital motion of a rotating inner cylinder in annular flowINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 2 2007Shunxin Feng Abstract In this paper, numerical calculations have been performed to analyse the influence of the orbital motion of an inner cylinder on annular flow and the forces exerted by the fluid on the inner cylinder when it is rotating eccentrically. The flow considered is fully developed laminar flow driven by axial pressure gradient. It is shown that the drag of the annular flow decreases initially and then increases with the enhancement of orbital motion, when it has the same direction as the inner cylinder rotation. If the eccentricity and rotation speed of the inner cylinder keep unchanged (with respect to the absolute frame of reference), and the orbital motion is strong enough that the azimuthal component (with respect to the orbit of the orbital motion) of the flow-induced force on the inner cylinder goes to zero, the flow drag nearly reaches its minimum value. When only an external torque is imposed to drive the eccentric rotation of the inner cylinder, orbital motion may occur and, in general, has the same direction as the inner cylinder rotation. Under this condition, whether the inner cylinder can have a steady motion state with force equilibrium, and even what type of motion state it can have, is related to the linear density of the inner cylinder. Copyright © 2006 John Wiley & Sons, Ltd. [source] Trends in the southern oscillation phenomenon and Australian rainfall and changes in their relationshipINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 3 2004Ramasamy Suppiah Abstract An attempt has been made to investigate decadal-scale trends in Australian rainfall and in the southern oscillation index (SOI) and their influence on the relationship between them. Monthly rainfall data from high-quality stations in Australia (from 1900 to 1995), India, Sri Lanka and Tahiti are used. The relationship between the SOI and Australian rainfall is positive, but shows decadal-scale variations during the past century. Although there were extended and severe El Niño events in the early 1990s and in 1997, Australia did not experience the expected severe rainfall deficiencies characteristic of previous events. However, severe drought conditions over eastern Australia were associated with a moderate El Niño event during 2002,03. Long-term fluctuations of March,May (MAM) rainfall show high-frequency variations, but trends during June,August (JJA), September,November (SON) and December,February (DJF) show low-frequency or decadal-scale variations. Trends and multi-decadal fluctuations in all-Australian spring (SON) and summer (DJF) rainfall are strongly dominated by rainfall trend fluctuations in northern and eastern Australia. Austral summer rainfall shows an increasing trend during the 1980s and 1990s, particularly in Queensland and New South Wales, despite the occurrence of extended and severe El Niños. However, some parts of New South Wales and Queensland experienced severe rainfall deficiencies during 2002,03 in conjunction with an El Niño event. The relationship between the SOI and rainfall on the interannual time scale is strong when the SOI and rainfall follow the same direction, but it is weak when they follow opposite directions on a decadal-time scale. The poor correlation during the 1920s and 1930s was due to a slightly increasing trend in the SOI and a stronger decreasing trend in rainfall. A weakening in the relationship between the SOI and rainfall in recent years, after the mid-1970s, is due to a small increase in rainfall in the 1980s and 1990s and a strong decrease in the SOI. Rainfall trends were enhanced (stronger decreases or increases) when the influence of the SOI (or El Niño-southern oscillation (ENSO)) was removed. Enhanced increases and decreases are particularly strong during SON and DJF, when the ENSO phenomenon is at the mature stage and also the influence on Australian rainfall is strong. The increasing trend in rainfall during the 1980s and 1990s in some parts of eastern Australia and the decreasing trend in the SOI result in more rainfall for a given SOI compared with the same SOI during the previous period, i.e. before the mid-1970s. A similar analysis was carried out for two periods, before and after 1972, for Tahiti, India and Sri Lanka. The upward or downward shift in regression lines is very clear during the season, that shows a strong relationship between rainfall and the SOI. Moreover, strengthening or weakening of the relationship between rainfall and the SOI is largely dependent on their multi-decadal variations and trends during the past century. Increases in rainfall during the 1980s and the 1990s and decreases in the SOI have weakened their relationship, both in Australia and India. Such a relationship gives more rainfall for a given SOI after 1973. The pattern was reversed for Sri Lanka, where rainfall during the second intermonsoon season has decreased. Analyses of trends in temperature at Darwin and Tahiti and of rainfall over Australia, India, Tahiti and Sri Lanka suggest a regional-scale change in climate, whereas the SOI reflects a change in the large-scale circulation pattern over the Indo-Pacific region after the mid-1970s. Copyright © 2004 Royal Meteorological Society [source] Tactile orientation constancy: Do proprioception and attention affect the tactile vertical?1JAPANESE PSYCHOLOGICAL RESEARCH, Issue 4 2006ATSUKI HIGASHIYAMA Abstract:,Tactile vertical, defined as the edge orientation that participants perceive to be vertical, was examined in four experiments. In Experiment 1, we touched the participants' cheek, lips, or hand with an edge and asked them to judge its orientation with regard to gravitational vertical, both when the stimulated body part was upright (or, in the case of the lips, aligned), and when it was tilted (lips, distorted). We found that when the head or hand was tilted forward 30°, or when the lower lip was distorted approximately 38° to the left or right, the tactile vertical shifted in the same direction by only a fraction (8.7, 8.6, and 36.3% for the cheek, lips, and hand, respectively) of the change in orientation of the stimulated region. The results indicated considerable, but usually incomplete, orientation constancy. In Experiment 2, we measured tactile vertical on the hand for forward tilts from 0° to 45°. We found that as the hand was tilted, the tactile vertical increasingly shifted in the same direction as the hand (i.e., a tactile Aubert effect). In Experiment 3, the effect of attentional focus on tactile vertical was examined by comparing the tactile vertical of participants who attended to body-centered coordinates, and others who attended to gravitation-centered coordinates. We found that focusing on body-centered coordinates caused a decrease in orientation constancy. We sought to examine the role of attention further in Experiment 4, measuring tactile vertical on the cheek of persons with temporomandibular disorders. Compared with normal participants, these participants displayed significantly lower constancy. The results were accounted for by a narrowing of attention to painful signals, so that proprioceptive information was attended to less. In conclusion, the degree of tactile orientation constancy that participants demonstrate varies as a function of body site and attentional focus. [source] The Extreme Future Stock Returns Following I/B/E/S Earnings SurprisesJOURNAL OF ACCOUNTING RESEARCH, Issue 5 2006JEFFREY T. DOYLE ABSTRACT We investigate the stock returns subsequent to quarterly earnings surprises, where the benchmark for an earnings surprise is the consensus analyst forecast. By defining the surprise relative to an analyst forecast rather than a time-series model of expected earnings, we document returns subsequent to earnings announcements that are much larger, persist for much longer, and are more heavily concentrated in the long portion of the hedge portfolio than shown in previous studies. We show that our results hold after controlling for risk and previously documented anomalies, and are positive for every quarter between 1988 and 2000. Finally, we explore the financial results and information environment of firms with extreme earnings surprises and find that they tend to be "neglected" stocks with relatively high book-to-market ratios, low analyst coverage, and high analyst forecast dispersion. In the three subsequent years, firms with extreme positive earnings surprises tend to have persistent earnings surprises in the same direction, strong growth in cash flows and earnings, and large increases in analyst coverage, relative to firms with extreme negative earnings surprises. We also show that the returns to the earnings surprise strategy are highest in the quartile of firms where transaction costs are highest and institutional investor interest is lowest, consistent with the idea that market inefficiencies are more prevalent when frictions make it difficult for large, sophisticated investors to exploit the inefficiencies. [source] Estimation of genetic parameters of type traits in Asturiana de los Valles beef cattle breedJOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 2 2002J. P. GUTIÉRREZ Ten type traits and a final score were analysed in 5868 records of the Asturiana de los Valles beef cattle breed. Traits were grouped into two classes: (i) traits scoring skeletal and muscular development and (ii) traits scoring adjustment to the breed standard. Heritabilities were moderate to low, ranging from 0.04 to 0.26. Genetic correlations among traits were, in general, in the same direction as, but higher than, phenotypic correlations. The genetic variability shown, in general, for the analysed traits would justify the inclusion of morphological assessment in the Asturiana de los Valles beef cattle breed sire selection programme. Main characteristics of the current type classification system are criticized. The knowledge of (co)variances among type and economically important productive and reproductive traits is recommended before revision of the classification methodology. Schätzung genetischer Parameter für Exterieurmerkmale in der Asturiana de los Valles Fleischrinderrasse 5868 registrierte Asturiana de los Valles Tiere wurden bezüglich 10 Exterieurmerkmalen und eines Gesamtwertes auf der Basis einer gewichteten Berücksichtigung dieser Einzelmerkmale untersucht. Die Merkmale wurden in zwei Klassen unterteilt: (i) Merkmale, die Skelett- und Muskelentwicklung betreffen und (ii) rassespezifische Merkmale. Die Heritabilitäten lagen zwischen 0,04 und 0,26. Genetische Korrelationen zwischen den Merkmalen waren allgemein mit den phänotypischen Korrelationen gleichgerichtet, aber mit höheren Werten. Die aufgezeigte genetische Variabilität der untersuchten Merkmale würde deren Eingliederung in die morphologische Bewertung im Rahmen des Asturiana de los Valles Fleischrinder Selektionsprogrammes für Bullen rechtfertigen. Wichtige Charakteristika der gegenwärtigen Exterieurbeurteilung werden kritisiert. Es wird empfohlen erst (Ko-)varianzen zwischen Exterieur und ökonomisch wichtigen Produktions- und Reproduktionsmerkmalen zu ermitteln, bevor die Bewertungsmethodik überarbeitet wird. [source] Adaptive radiation into ecological niches with eruptive dynamics: a comparison of tenthredinid and diprionid sawfliesJOURNAL OF ANIMAL ECOLOGY, Issue 3 2005PETER W. PRICE Summary 1We tested the hypothesis that the bottom-up influence of coniferous plant resources promotes the probability of outbreak or eruptive dynamics in sawflies. The literature was examined for three geographical regions , North America north of Mexico, Europe and Japan. 2In each region tenthredinid sawflies (Hymenoptera: Tenthredinidae) were significantly more likely to be eruptive on conifers than on angiosperms. 3The diprionid sawflies (Hymenoptera: Diprionidae) that attack conifers exclusively showed a significantly higher probability of eruptive dynamics than the tenthredinid sawflies on angiosperms in two regions, North America and Europe, and in Japan the trend was in the same direction. 4The probability of species showing eruptive dynamics on coniferous hosts was not significantly different among tenthredinids and diprionids on conifers in North America, Europe and Japan. 5The weight of evidence supports the hypothesis of conifers supporting a higher percentage of eruptive species than angiosperms. 6In the adaptive radiation of tenthredinid sawflies from flowering plants onto conifers, larches (Larix) appear to be particularly favourable for colonization, but pines (Pinus) have not been colonized in any region, a pattern likely to be explained by the growth characteristics of the host plants. 7Among tenthredinid species in Europe, where sawfly/host relationships are best known, there is a significant trend for an increasing proportion of outbreaking species from herbs, to shrubs, to trees. 8The results indicate for the first time the strong bottom-up effects of plant resources on the population dynamics of sawflies, involving general features of host plant taxa and growth characteristics. [source] Judgement of hygienic quality of roughage in horse stables in SwitzerlandJOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 4 2008B. Wichert Summary In 46 horse farms all over Switzerland, the hygienic quality of the roughage (including silages) was investigated. Therefore, a macroscopic examination as well as the microbial counts (bacteria, yeasts and moulds) was carried out. Further, the contents of lipopolysaccharides (LPS) and the contamination with deoxynivalenol (DON) were determined. In all roughages, the dry matter (DM) content was measured and in silages additionally the pH was measured. Predominantly, the straw showed a lower hygienic quality than hay and silages. The LPS contents were significantly higher in straw than those in hay samples. The macroscopic examination and the microbial counts showed a tendency in the same direction. Eight straw samples and one hay sample with DON contamination were found. The silages showed a DM content with a median of 65.8%. The pH of those silages was between 4.3 and 5.9. Despite the high values of DM and pH, the silages showed mainly a high hygienic quality. In total, the hygienic standard of straw was worse than that of hay. This should be taken into account also in straw used as bedding as much as the hygienic quality of hay. [source] Association with replication between estrogen-related receptor , (ESRR,) Polymorphisms and bone phenotypes in women of European ancestryJOURNAL OF BONE AND MINERAL RESEARCH, Issue 4 2010Latifa Elfassihi Abstract Osteoporosis is a bone disease characterized by low bone mineral density (BMD), a highly heritable polygenic trait. Women are more prone than men to develop osteoporosis owing to a lower peak bone mass and accelerated bone loss at menopause. Lack of estrogen thus is a major risk factor for osteoporosis. In addition to having strong similarity to the estrogen receptor 1 (ESR1), the orphan nuclear estrogen-related receptor , (ESRR,) is widely expressed and shows overlap with ESR1 expression in tissues where estrogen has important physiologic functions. For these reasons, we have undertaken a study of ESRR, sequence variants in association with bone measurements [heel quantitative ultrasound (QUS) by measurements of broadband ultrasound attenuation (BUA), speed of sound (SOS), and stiffness index (SI) and dual-energy X-ray absorptiometry (DXA) at the femoral neck (FN) and lumbar spine (LS)]. A silent variant was found to be associated with multiple bone measurements (LS, BUA, SOS, and SI), the p values ranging from .006 to .04 in a sample of 5144 Quebec women. The region of this variant was analyzed using the HapMap database and the Gabriel method to define a block of 20,kb. Using the Tagger method, eight TagSNPs were identified and genotyped in a sample of 1335 women. Four of these SNPs capture the five major block haplotypes. One SNP (rs2818964) and one haplotype were significantly associated with multiple bone measures. All SNPs involved in the associations were analyzed in two other sample sets with significant results in the same direction. These results suggest involvement of ESRR, in the determination of bone density in women. © 2010 American Society for Bone and Mineral Research [source] Fractionation of Electrograms and Linking of Activation During Pharmacologic Cardioversion of Persistent Atrial Fibrillation in the GoatJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 5 2004ZHAOLIANG SHAN M.D. Introduction: During atrial fibrillation (AF), there is fractionation of extracellular potentials due to head-to-tail interaction and slow conduction of fibrillation waves. We hypothesized that slowing of the rate of AF by infusion of a Class I drug would increase the degree of organization of AF. Methods and Results: Seven goats were instrumented with 83 epicardial electrodes on the left atrium, left atrial appendage, Bachmann's bundle, right atrium, and right atrial appendage. AF was induced and maintained by an automatic atrial fibrillator. After AF had persisted for 4 weeks, the Class IC drug cibenzoline was infused at a rate of 0.1 mg/kg/min. AF cycle length (AFCL), the percentage of fractionated potentials, conduction velocity (CV), and direction of propagation of the fibrillation waves were measured during baseline, after AFCL was increased by 20, 40, 60, and 80 ms, and shortly before cardioversion. Infusion of cibenzoline increased the mean of the median AFCLs from 96 ± 6 ms to 207 ± 43 ms (P < 0.0001). The temporal variation in AFCL in different parts of the atria was 8% to 20% during control and, with the exception of Bachmann's bundle, was not significantly reduced during cibenzoline infusion. CV decreased from 76 ± 14 ms to 52 ± 9 cm/s (P < 0.01). Cibenzoline increased the percentage of single potentials from 81%± 4% to 91%± 4% (P < 0.01) and decreased the incidence of double potentials from 14%± 4% to 7 ± 5% (P < 0.01) and multiple potentials from 5%±% to 1%± 2% (P < 0.001). Whereas during control, linking (consecutive waves propagating in the same direction) during seven or more beats occurred in 9%± 15% of the cycles, after cibenzoline the degree of linking had increased to 40%± 33% (P < 0.05). During the last two beats before cardioversion, there was a sudden prolongation in AFCL from 209 ± 37 ms to 284 ± 92 ms (P < 0.01) and a strong reduction in fractionated potentials (from 22%± 12% to 6%± 5%, P < 0.05). Conclusion: The Class IC drug cibenzoline causes a decrease in fractionation of fibrillation electrograms and an increase in the degree of linking during AF. This supports the observation that Class I drugs widen the excitable gap during AF. (J Cardiovasc Electrophysiol, Vol. 15, pp. 572-580, May 2004) [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||