bluuebunny/crossref_metadata_2025 huggingface dataset:
Hypoxia tolerance in elasmobranchs. II. Cardiovascular function and tissue metabolic responses during progressive and relative hypoxia exposures
Authors: Speers-Roesch Ben , Brauner Colin J. , Farrell Anthony P. , Hickey Anthony J. R. , Renshaw Gillian M. C. , Wang Yuxiang S. , Richards Jeffrey G.
Published: December 2011

Cardiovascular function and metabolic responses of the heart and other tissues during hypoxia exposure were compared between the hypoxia-tolerant epaulette shark (Hemiscyllium ocellatum) and the hypoxia-sensitive shovelnose ray (Aptychotrema rostrata). In both species, progressive hypoxia exposure caused increases in stroke volume and decreases in heart rate, cardiac output, cardiac power output (CPO, an assessment of cardiac energy demand) and dorsal aortic blood pressure, all of which occurred at or below each species' critical PO2 for whole-animal O2 consumption rate, (Pcrit). In epaulette sharks, which have a lower Pcrit than shovelnose rays, routine levels of cardiovascular function were maintained to lower water PO2 levels and the changes from routine levels during hypoxia exposure were smaller compared with those for the shovelnose ray. The maintenance rather than depression of cardiovascular function during hypoxia exposure may contribute to the superior hypoxia tolerance of the epaulette shark, presumably by improving O2 delivery and waste removal. Compared with shovelnose rays, epaulette sharks were also better able to maintain a stable cardiac high-energy phosphate pool and to minimize metabolic acidosis and lactate accumulation in the heart (despite higher CPO) and other tissues during a 4 h exposure to 40% of their respective Pcrit (referred to as a relative hypoxia exposure), which results in similar hypoxaemia in the two species (∼16% Hb–O2 saturation). These different metabolic responses to relative hypoxia exposure suggest that variation in hypoxia tolerance among species is not solely dictated by differences in O2 uptake and transport but also by tissue-specific metabolic responses. In particular, lower tissue [lactate] accumulation in epaulette sharks than in shovelnose rays during relative hypoxia exposure suggests that enhanced extra-cardiac metabolic depression occurs in the former species. This could facilitate strategic utilization of available O2 for vital organs such as the heart, potentially explaining the greater hypoxic cardiovascular function of epaulette sharks.
Oxygen utilization and the branchial pressure gradient during ram ventilation of the shortfin mako,Isurus oxyrinchus: is lamnid shark–tuna convergence constrained by elasmobranch gill morphology?
Authors: Wegner Nicholas C. , Lai N. Chin , Bull Kristina B. , Graham Jeffrey B.
Published: December 2011

Ram ventilation and gill function in a lamnid shark, the shortfin mako, Isurus oxyrinchus, were studied to assess how gill structure may affect the lamnid–tuna convergence for high-performance swimming. Despite differences in mako and tuna gill morphology, mouth gape and basal swimming speeds, measurements of mako O2 utilization at the gills (53.4±4.2%) and the pressure gradient driving branchial flow (96.8±26.1 Pa at a mean swimming speed of 38.8±5.8 cm s–1) are similar to values reported for tunas. Also comparable to tunas are estimates of the velocity (0.22±0.03 cm s–1) and residence time (0.79±0.14 s) of water though the interlamellar channels of the mako gill. However, mako and tuna gills differ in the sites of primary branchial resistance. In the mako, approximately 80% of the total branchial resistance resides in the septal channels, structures inherent to the elasmobranch gill that are not present in tunas. The added resistance at this location is compensated by a correspondingly lower resistance at the gill lamellae accomplished through wider interlamellar channels. Although greater interlamellar spacing minimizes branchial resistance, it also limits lamellar number and results in a lower total gill surface area for the mako relative to tunas. The morphology of the elasmobranch gill thus appears to constrain gill area and, consequently, limit mako aerobic performance to less than that of tunas.
Earliest ciliary swimming effects vertical transport of planktonic embryos in turbulence and shear flow
Authors: McDonald Kathryn A.
Published: December 2011

Eggs released by broadcast-spawning marine invertebrates are often negatively buoyant. Blastulae and gastrulae of these species are commonly motile, with passive stability that leads to upward swimming in still water. The earliest occurrence of swimming in developing embryos of diverse invertebrates may therefore permit vertical migration in nature. I used turbulent and laminar shear flows to investigate: (1) the speed and direction of transport of non-motile and newly swimming stages of the echinoids Dendraster excentricus and Strongylocentrotus purpuratus in turbulence, and (2) the limit of stable vertical orientation in swimming blastulae of D. excentricus. Swimming contributed significantly to the rate of upward transport of D. excentricus in turbulence experiments where the kinetic energy dissipation rate (ε) was ∼10–2cm2s–3. However, swimming significantly reduced the rate of upward transport of S. purpuratus blastulae in turbulence, suggesting that passively stable swimmers of this species were turned from the vertical, crossed flow-lines, and migrated into downwelling. Observations of swimming in laminar shear indicate that D. excentricus swimming blastulae maintain a vertical orientation until shear approaches 0.26s–1, equivalent to sub-microscale shear in turbulence where ε is ∼10–3cm2s–3. Swimming speeds of D. excentricus showed an unexpected dependence on shear, indicating that greater shear (within limits) can enhance speed of ciliary swimming. In D. excentricus, swimming by newly hatched blastulae should support upward migration in turbulence characteristic of coastal surface waters, whereas species differences in passive stability and swimming responses to shear may lead to differences in vertical transport and subsequent dispersal.
Surface roughness effects on attachment ability of the spider Philodromus dispar (Araneae, Philodromidae)
Authors: Wolff Jonas O. , Gorb Stanislav N.
Published: December 2011

The morphology of the tarsal attachment system of the running spider Philodromus dispar Walckenaer 1826 (Araneae, Philodomidae) was studied using scanning electron microscopy and its performance was experimentally tested in traction force measurements. Each pretarsus bears a hierarchically built hairy adhesive pad that consists of a dense array of flattened setae covered with numerous microtrichia on the substrate-facing side. Microtrichia carry spatulate end tips that allow close contact with the substrate. Forces were estimated on tethered living specimens on rough epoxy resin surfaces (asperity size 0.3, 1, 3, 9 and 12 μm) and on a smooth surface as a control. A strong reduction in adhesion was observed for substrates with an asperity size of 0.3 and 1 μm. Comparison of the present data with previous results of different organisms demonstrates that the difference in force reduction on rough substrata depends on the dimensions of terminal contact elements (spatulae).
A robotic fish caudal fin: effects of stiffness and motor program on locomotor performance
Authors: Esposito Christopher J. , Tangorra James L. , Flammang Brooke E. , Lauder George V.
Published: December 2011

We designed a robotic fish caudal fin with six individually moveable fin rays based on the tail of the bluegill sunfish, Lepomis macrochirus. Previous fish robotic tail designs have loosely resembled the caudal fin of fishes, but have not incorporated key biomechanical components such as fin rays that can be controlled to generate complex tail conformations and motion programs similar to those seen in the locomotor repertoire of live fishes. We used this robotic caudal fin to test for the effects of fin ray stiffness, frequency and motion program on the generation of thrust and lift forces. Five different sets of fin rays were constructed to be from 150 to 2000 times the stiffness of biological fin rays, appropriately scaled for the robotic caudal fin, which had linear dimensions approximately four times larger than those of adult bluegill sunfish. Five caudal fin motion programs were identified as kinematic features of swimming behaviors in live bluegill sunfish, and were used to program the kinematic repertoire: flat movement of the entire fin, cupping of the fin, W-shaped fin motion, fin undulation and rolling movements. The robotic fin was flapped at frequencies ranging from 0.5 to 2.4 Hz. All fin motions produced force in the thrust direction, and the cupping motion produced the most thrust in almost all cases. Only the undulatory motion produced lift force of similar magnitude to the thrust force. More compliant fin rays produced lower peak magnitude forces than the stiffer fin rays at the same frequency. Thrust and lift forces increased with increasing flapping frequency; thrust was maximized by the 500× stiffness fin rays and lift was maximized by the 1000× stiffness fin rays.
The energetics of running stability: costs of transport in grass-cutting ants depend on fragment shape
Authors: Moll Karin , Federle Walter , Roces Flavio
Published: December 2011

Grass-cutting ants (Atta vollenweideri) carry fragments that can be many times heavier and longer than the ants themselves and it is important for them to avoid falling over during load transport. To investigate whether the energetic costs of transport are affected by the need to maintain stability, the rate of CO2 production was measured in both unladen workers and workers carrying standardized paper fragments of different size and shape. We tested: (1) the effect of mass by comparing workers carrying either light or heavy fragments of the same size, and (2) the effect of shape by comparing short and long fragments of the same mass. Consistent with previous studies, metabolic rate increased but running speed remained constant when ants carried heavier fragments. The net cost of transport (normalized to the total mass of ant and fragment) was the same for heavy and light fragments, and did not differ from the costs of carrying a unit body mass. Ants carrying long fragments showed similar metabolic rates but ran significantly slower than ants carrying short fragments. As a consequence, net cost of transport was significantly higher for long fragments than for short ones, and higher than the costs of carrying a unit body mass. The observed reduction in running speed is likely a result of the ants' need to maintain stability. When the absolute costs of transport were compared, smaller ants required more energy to carry heavier and longer fragments than larger workers, but the opposite was found for lighter and shorter fragments. The absolute costs of transport per unit fragment mass suggest that it is energetically advantageous for a colony to allocate smaller workers for the transport of small fragments and larger workers for large fragments. The present results underline the importance of biomechanical factors for the understanding of leaf-cutting ant foraging strategies.
Point of no return in diving emperor penguins: is the timing of the decision to return limited by the number of strokes?
Authors: Shiomi Kozue , Sato Katsufumi , Ponganis Paul J.
Published: December 2011

At some point in a dive, breath-hold divers must decide to return to the surface to breathe. The issue of when to end a dive has been discussed intensively in terms of foraging ecology and behavioral physiology, using dive duration as a temporal parameter. Inevitably, however, a time lag exists between the decision of animals to start returning to the surface and the end of the dive, especially in deep dives. In the present study, we examined the decision time in emperor penguins under two different conditions: during foraging trips at sea and during dives at an artificial isolated dive hole. It was found that there was an upper limit for the decision-to-return time irrespective of dive depth in birds diving at sea. However, in a large proportion of dives at the isolated dive hole, the decision-to-return time exceeded the upper limit at sea. This difference between the decision times in dives at sea versus the isolated dive hole was accounted for by a difference in stroke rate. The stroke rates were much lower in dives at the isolated hole and were inversely correlated with the upper limit of decision times in individual birds. Unlike the decision time to start returning, the cumulative number of strokes at the decision time fell within a similar range in the two experiments. This finding suggests that the number of strokes, but not elapsed time, constrained the decision of emperor penguins to return to the surface. While the decision to return and to end a dive may be determined by a variety of ecological, behavioral and physiological factors, the upper limit to that decision time may be related to cumulative muscle workload.
Ketamine in Adult Emergency Medicine: Controversies and Recent Advances
Authors: Sih Kendra , Campbell Samuel G , Talion John M , Magee Kirk , Zed Peter J
Published: December 2011

Objective:

To review the evidence for the use of ketamine in adult emergency medicine for procedural sedation and analgesia (PSA) and rapid sequence intubation (RSI), as well as to focus on the issues of recovery agitation, combination with propofol for PSA, and the use of ketamine as an induction agent in patients with acute head injury in need of definitive airway management.

Data Sources:

PubMed (1949-July 2011), EMBASE (1980-July 2011), Google Scholar (to July 2011), International Pharmaceutical Abstracts (1964-July 2011), and Cochrane databases were searched independently. A manual search of references was also performed,

Study Selection:

English-language, full reports of experimental and observational studies evaluating ketamine in adults undergoing PSA and RSI in the emergency department (ED) were Included if they reported efficacy or safety outcomes.

Data Extraction:

Two reviewers independently assessed each article for inclusion, data extraction, and study limitations.

Data Synthesis:

Six studies that used ketamine for PSA were included. The majority reported adequate sedation with high patient satisfaction and lack of pain and procedural recall. There is no evidence to support the superiority of a combination of ketamine and propofol compared to propofol alone for PSA in adults. Recovery agitation is common but can be minimized with premedication with midazolam (number needed to treat 6). Two studies were identified that evaluated the role of ketamine for induction during RSI in the ED, Although ketamine is not a first-line agent for RSI, it is an alternative and may be used as an induction agent in patients requiring endotracheal intubation.

Conclusions:

Ketamine is an effective agent in adults undergoing PSA and RSI in the ED. The best available evidence provides sufficient confidence to consider use of this agent in the ED.
Disparities in Blood Pressure Control Within a Community-Based Provider Network: An Exploratory Analysis
Authors: Romanelli Robert J , Schiro Timothy A , Jukes Trevor , Wong Ken S , Ishisaka Denis Y
Published: December 2011

Background:

Despite treatment for hypertension, blood pressure (BP) remains uncontrolled in many individuals. Identification of patterns in BP control may inform strategies to improve treatment and optimize health outcomes.

Objective:

To examine patterns in BP control among individuals receiving antihypertensive treatment in a diverse, community-based provider network.

Methods:

In this retrospective exploratory analysis, a total of 51.772 hypertensive subjects were identified in the electronic medical record between January 1, 2007, and June 30, 2010, who were aged 18 years or older, with 2 or more claims for antihypertensive medication, documented race/ethnicity, and 1 or more documented BP readings.

Results:

On the basis of Joint National Committee VII guidelines, 76.4% of nondiabetic patients had their BP controlled with treatment (<140/90 mm Hg) and 52.3% of those with diabetes had their BP controlled with treatment (<130/80 mm Hg). The overall rate of BP control was 71.4%. Factors associated with controlled BP included younger age, lower disease burden, better medication adherence, fewer concurrent prescriptions, lower prescription copayments, and living in a region with a higher median household income. Furthermore, when adjusting for age, sex, and disease burden, black (OR 0.68; 95% Cl 0.62 to 0.75; p < 0.001), Hispanic (OR 0.80; 95% Cl 0.74 to 0.86; p < 0.001), and other race/ethnic group (OR 0.81; 95% Cl 0.70 to 0.94; p = 0.005) individuals were less likely than white individuals to have their treated BP controlled. Among nondiabetic hypertensive subjects with controlled BP, the most frequently prescribed therapy was a β-blocker or an angiotensin-converting enzyme (ACE) inhibitor across race/ethnicities; however, those who were black were most frequently prescribed a diuretic or calcium channel blocker. Among diabetic patients with controlled BP, the most frequently prescribed therapy was an ACE inhibitor, regardless of race/ethnicity.

Conclusions:

Potential disparities, particularly among diabetic individuals and those of minority race/ethnicity, were found with regard to BP control and the agents used to treat hypertension. Future studies should address these disparities by designing interventions to improve the treatment of hypertension in high-risk populations.
Emotion-Induced Engagement in Internet Video Advertisements
Authors: Teixeira Thales , Wedel Michel , Pieters Rik
Published: December 2011

This study shows how advertisers can leverage emotion and attention to engage consumers in watching Internet video advertisements. In a controlled experiment, the authors assessed joy and surprise through automated facial expression detection for a sample of advertisements. They assessed concentration of attention through eye tracking and viewer retention by recording zapping behavior. This allows tests of predictions about the interplay of these emotions and interperson attention differences at each point in time during exposure. Surprise and joy effectively concentrate attention and retain viewers. However, importantly, the level rather than the velocity of surprise affects attention concentration most, whereas the velocity rather than the level of joy affects viewer retention most. The effect of joy is asymmetric, with higher gains for increases than losses for decreases. Using these findings, the authors develop representative emotion trajectories to support ad design and testing.
Anticipatory Saccade Target Processing and the Presaccadic Transfer of Visual Features
Authors: Zirnsak Marc , Gerhards Ricarda G. K. , Kiani Roozbeh , Lappe Markus , Hamker Fred H.
Published: December 2011

As we shift our gaze to explore the visual world, information enters cortex in a sequence of successive snapshots, interrupted by phases of blur. Our experience, in contrast, appears like a movie of a continuous stream of objects embedded in a stable world. This perception of stability across eye movements has been linked to changes in spatial sensitivity of visual neurons anticipating the upcoming saccade, often referred to as shifting receptive fields (Duhamel et al., 1992; Walker et al., 1995; Umeno and Goldberg, 1997; Nakamura and Colby, 2002). How exactly these receptive field dynamics contribute to perceptual stability is currently not clear. Anticipatory receptive field shifts toward the future, postsaccadic position may bridge the transient perisaccadic epoch (Sommer and Wurtz, 2006; Wurtz, 2008; Melcher and Colby, 2008). Alternatively, a presaccadic shift of receptive fields toward the saccade target area (Tolias et al., 2001) may serve to focus visual resources onto the most relevant objects in the postsaccadic scene (Hamker et al., 2008). In this view, shifts of feature detectors serve to facilitate the processing of the peripheral visual content before it is foveated. While this conception is consistent with previous observations on receptive field dynamics and on perisaccadic compression (Ross et al., 1997; Morrone et al., 1997; Kaiser and Lappe, 2004), it predicts that receptive fields beyond the saccade target shift toward the saccade target rather than in the direction of the saccade. We have tested this prediction in human observers via the presaccadic transfer of the tilt-aftereffect (Melcher, 2007).
Sleep Spindles in Humans: Insights from Intracranial EEG and Unit Recordings
Authors: Andrillon Thomas , Nir Yuval , Staba Richard J. , Ferrarelli Fabio , Cirelli Chiara , Tononi Giulio , Fried Itzhak
Published: December 2011

Sleep spindles are an electroencephalographic (EEG) hallmark of non-rapid eye movement (NREM) sleep and are believed to mediate many sleep-related functions, from memory consolidation to cortical development. Spindles differ in location, frequency, and association with slow waves, but whether this heterogeneity may reflect different physiological processes and potentially serve different functional roles remains unclear. Here we used a unique opportunity to record intracranial depth EEG and single-unit activity in multiple brain regions of neurosurgical patients to better characterize spindle activity in human sleep. We find that spindles occur across multiple neocortical regions, and less frequently also in the parahippocampal gyrus and hippocampus. Most spindles are spatially restricted to specific brain regions. In addition, spindle frequency is topographically organized with a sharp transition around the supplementary motor area between fast (13–15 Hz) centroparietal spindles often occurring with slow-wave up-states, and slow (9–12 Hz) frontal spindles occurring 200 ms later on average. Spindle variability across regions may reflect the underlying thalamocortical projections. We also find that during individual spindles, frequency decreases within and between regions. In addition, deeper NREM sleep is associated with a reduction in spindle occurrence and spindle frequency. Frequency changes between regions, during individual spindles, and across sleep may reflect the same phenomenon, the underlying level of thalamocortical hyperpolarization. Finally, during spindles neuronal firing rates are not consistently modulated, although some neurons exhibit phase-locked discharges. Overall, anatomical considerations can account well for regional spindle characteristics, while variable hyperpolarization levels can explain differences in spindle frequency.
Chronic Perinatal Hypoxia Reduces Glutamate–Aspartate Transporter Function in Astrocytes through the Janus Kinase/Signal Transducer and Activator of Transcription Pathway
Authors: Raymond Matthew , Li Peijun , Mangin Jean-Marie , Huntsman Molly , Gallo Vittorio
Published: December 2011

The cellular and molecular mechanisms that govern the response of the perinatal brain to injury remain largely unexplored. We investigated the role of white matter astrocytes in a rodent model of diffuse white matter injury produced by exposing neonatal mice to chronic hypoxia—a paradigm that mimics brain injury in premature infants. We demonstrate the absence of reactive gliosis in the immature white matter following chronic hypoxia, as determined by astrocyte proliferation index and glial fibrillary acidic protein levels. Instead, Nestin expression in astrocytes is transiently increased, and the glial-specific glutamate transporters glutamate–aspartate transporter (GLAST) and glutamate transporter 1 (GLT-1) are reduced. Finally, we demonstrate that Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling—which is important in both astrocyte development and response to injury—is reduced in the white matter following hypoxia, as well as in primary astrocytes exposed to hypoxiain vitro. Hypoxia and JAK/STAT inhibition reduce glutamate transporter expression in astrocytes, but unlike hypoxia JAK/STAT inhibition downregulates GLAST expression without affecting GLT-1, as demonstratedin vitroby treatment with JAK inhibitor I andin vivoby treatment with the JAK/STAT inhibitor AG490 [(E)-2-cyano-3-(3,4-dihydrophenyl)-N-(phenylmethyl)-2-propenamide]. Our findings (1) demonstrate specific changes in astrocyte function after perinatal hypoxia, which might contribute to the particular pathogenesis of perinatal white matter injury, (2) provide evidence that at least part of these changes result from a disturbance of the JAK/STAT pathway by hypoxia, and (3) identify JAK/STAT signaling as a potential therapeutic target to restore normal GLAST expression and uptake of glutamate after perinatal brain injury.
Binocular Disparity Tuning and Visual–Vestibular Congruency of Multisensory Neurons in Macaque Parietal Cortex
Authors: Yang Yun , Liu Sheng , Chowdhury Syed A. , DeAngelis Gregory C. , Angelaki Dora E.
Published: December 2011

Many neurons in the dorsal medial superior temporal (MSTd) and ventral intraparietal (VIP) areas of the macaque brain are multisensory, responding to both optic flow and vestibular cues to self-motion. The heading tuning of visual and vestibular responses can be either congruent or opposite, but only congruent cells have been implicated in cue integration for heading perception. Because of the geometric properties of motion parallax, however, both congruent and opposite cells could be involved in coding self-motion when observers fixate a world-fixed target during translation, if congruent cells prefer near disparities and opposite cells prefer far disparities. We characterized the binocular disparity selectivity and heading tuning of MSTd and VIP cells using random-dot stimuli. Most (70%) MSTd neurons were disparity selective with monotonic tuning, and there was no consistent relationship between depth preference and congruency of visual and vestibular heading tuning. One-third of disparity-selective MSTd cells reversed their depth preference for opposite directions of motion [direction-dependent disparity tuning (DDD)], but most of these cells were unisensory with no tuning for vestibular stimuli. Inconsistent with previous reports, the direction preferences of most DDD neurons do not reverse with disparity. By comparison to MSTd, VIP contains fewer disparity-selective neurons (41%) and very few DDD cells. On average, VIP neurons also preferred higher speeds and nearer disparities than MSTd cells. Our findings are inconsistent with the hypothesis that visual/vestibular congruency is linked to depth preference, and also suggest that DDD cells are not involved in multisensory integration for heading perception.
Altered Brain Activation During Visuomotor Integration in Chronic Active Cannabis Users: Relationship to Cortisol Levels
Authors: King George R. , Ernst Thomas , Deng Weiran , Stenger Andrew , Gonzales Rachael M. K. , Nakama Helenna , Chang Linda
Published: December 2011

Cannabis is the most abused illegal substance in the United States. Alterations in brain function and motor behavior have been reported in chronic cannabis users, but the results have been variable. The current study aimed to determine whether chronic active cannabis use in humans may alter psychomotor function, brain activation, and hypothalamic-pituitary-axis (HPA) function in men and women. Thirty cannabis users (16 men, 14 women, 18–45 years old) and 30 nondrug user controls (16 men, 14 women, 19–44 years old) were evaluated with neuropsychological tests designed to assess motor behavior and with fMRI using a 3 Tesla scanner during a visually paced finger-sequencing task, cued by a flashing checkerboard (at 2 or 4 Hz). Salivary cortisol was measured to assess HPA function. Male, but not female, cannabis users had significantly slower performance on psychomotor speed tests. As a group, cannabis users had greater activation in BA 6 than controls, while controls had greater activation in the visual area BA 17 than cannabis users. Cannabis users also had higher salivary cortisol levels than controls (p= 0.002). Chronic active cannabis use is associated with slower and less efficient psychomotor function, especially in male users, as indicated by a shift from regions involved with automated visually guided responses to more executive or attentional control areas. The greater but altered brain activities may be mediated by the higher cortisol levels in the cannabis users, which in turn may lead to less efficient visual–motor function.
Reduced White Matter Integrity Is Related to Cognitive Instability
Authors: Fjell Anders. M. , Westlye Lars. T. , Amlien Inge K. , Walhovd Kristine B.
Published: December 2011

Increased performance variability has been demonstrated in several groups and conditions, including aging and cognitive decline. Structural brain characteristics underlying this phenomenon have so far been elusive. However, there is reason to expect that disconnectivity in associative pathways, whether caused by immature or degraded white matter (WM) tracts, will increase performance variability by neural noise. The aim of this study was to test whether the quality of WM, measured by diffusion tensor imaging, is related to performance variability in healthy adults. Intraindividual standard deviation of the reaction time (sdRT) across trials and median reaction time (mRT) from 270 participants were obtained from a speeded continuous performance task (Eriksen flanker task) with two conditions (congruent, incongruent). Tract-based spatial statistics was used to test the relationship with diffusion characteristics [fractional anisotropy (FA), mean diffusion (MD), radial diffusion (RD), axial diffusion (AD)]. Robust relationships between sdRT and all diffusion measures were found in most WM areas, independently of mRT, age, and sex. The effects were anatomically more widespread in the congruent than the incongruent condition, covering almost 50% of the voxels for RD and MD, and >25% of the voxels for FA and AD. Partial betas were in the range 0.45–0.55, and the strength of the relationships increased significantly with age. For mRT, the effects were smaller and unstable across condition. We concluded that performance variability is a likely consequence of individual differences in WM integrity, and that it is a promising behavioral correlate of individual differences in WM microstructure.
Early Improved and Late Defective Cognition Is Reflected by Dendritic Spines in Tau.P301L Mice
Authors: Kremer Anna , Maurin Hervé , Demedts David , Devijver Herman , Borghgraef Peter , Van Leuven Fred
Published: December 2011

Cognitive demise correlates with progressive brain tauopathy in dementing patients. Improved cognition of young Tau.P301L mice contrasts with dysfunction later in life and remains unexplained (Boekhoorn et al., 2006). To unravel early mechanisms, we composed a correlative time line of clinical symptoms, cognitive defects, and biochemical and pathological traits, including comprehensive analysis of dendritic spines in specified regions of the cortex and hippocampus of young and adult Tau.P301L mice. Remarkably, young Tau.P301L mice have not more, but more mature spines than wild-type mice, revealing the anatomical substrate for their improved cognition and LTP. Spine maturation remained high in the hippocampus of adult Tau.P301L mice. However, spines regressed in length paralleling impaired cognition and increased Tau phosphorylation (Terwel et al., 2005). Conversely, spine maturation was unaffected in adult Tau.4R mice, while spine density was increased and length reduced similar to Tau.P301L mice. To explain how protein Tau promoted spinogenesis, we analyzed hippocampal synaptosomes and dendritic spines for mouse and human Tau. While synaptosomes were positive for both mouse and human Tau, weak variable reaction in spines was observed only after fixation according to Bouin. Mouse Tau was absent from spines in wild-type mice, dissociating the pathological actions of Tau in transgenic mice by relocalization into dendrites and spines from the physiological actions of protein Tau in axons only. We conclude that mutant protein Tau modulates cognition and morphology of spines similarly and in both directions, with pathology later in life coinciding with increased phosphorylation and relocalization of Tau from axons to soma and processes.
Hippocampal Function in Healthy Carriers of theCLUAlzheimer's Disease Risk Variant
Authors: Erk Susanne , Meyer-Lindenberg Andreas , Opitz von Boberfeld Carola , Esslinger Christine , Schnell Knut , Kirsch Peter , Mattheisen Manuel , Mühleisen Thomas W. , Cichon Sven , Witt Stephanie H. , Rietschel Marcella , Nöthen Markus M. , Walter Henrik
Published: December 2011

Alzheimer's disease is a devastating, common, progressive dementia with considerable heritability. Recently, a genetic variant associated with the disease was discovered atCLU(rs11136000) with genome-wide support. Here we show, using an imaging genetics approach in a large genotyped sample, that healthy carriers of the variant exhibit altered coupling between hippocampus and prefrontal cortex during memory processing, mirroring clinical evidence of disturbed connectivity in patients and providing a neurogenetic mechanism for CLU-associated risk and protection.
Different Representations of Potential and Selected Motor Plans by Distinct Parietal Areas
Authors: Cui He , Andersen Richard A.
Published: December 2011

Traditional theories have considered decision making as a separate neural process occurring before action planning. However, recent neurophysiological studies of spatial target selection have suggested that decision making and motor planning may be performed in an integrated manner. It was proposed that multiple potential plans are concurrently formed and the ultimately selected action simultaneously emerges within the same circuits (Shadlen and Newsome, 2001; Cisek and Kalaska, 2010). In the present study, we recorded from the parietal reach region (PRR) and dorsal area 5 (area 5d) in the posterior parietal cortex (PPC) while monkeys performed a nonspatial effector (saccade vs reach) choice task. The results show that PRR encodes potential and selected reach plans whereas area 5d encodes only selected reach plans, suggesting a serial visuomotor cortical circuitry for nonspatial effector decisions. Thus, there appears to be a different flow of processing for decisions and planning for spatial target selection, which is more integrated, and nonspatial effector decisions between eye and limb movements, which are more serial.
Platão e o pensamento grego
Authors: Souza Netto Francisco Benjamin de
Published: December 2011

O Pensamento de Platão tem o encanto das estátuas de Dédalo: esvai-se pelos meandros do discurso, tão logo se pretenda travar com ele uma relação de domínio. A sua correta interpretação exige que se assuma a Polis como o lugar natural no qual emerge, como a limitação que ele se propõe superar remontando à Fysis e ao Ser. Fazê-lo importa em captar o movimento que lhe é próprio, partindo da questão sobre o ente e visualizando a resposta como o enunciado de sua essência, isto é, do eidos, e de seu fundamento, isto é, do Bem como nome próprio do Ser. Determinando o ente em sua essência, o eidos é a medida de toda a adequação, da episteme à Polis.
Objeto A: ética e estrutura
Authors: Costa-Moura Fernanda , Costa-Moura Renata
Published: December 2011

O trabalho distingue o estabelecimento do conceito de objeto a por Lacan, a partir dos objetos da pulsão, destacando o advento do objeto a como operação conceitual que enceta a transposição da relação sujeito/objeto, do campo do conhecimento para o campo da ética. Ressituando-se este objeto como estrutural, conclui-se que a afirmação lacaniana de uma causalidade que incide neste plano objetal, como constitutiva da condição desejante do sujeito, demarca um novo estatuto da problemática ética, a qual queda referida doravante não mais à deliberação do sujeito, e sim a um destino de assunção desta causalidade em seu efeito de desejo.
A estrutura em psicanálise: uma enunciação desde Freud
Authors: Sadala Glória , Martinho Maria Helena
Published: December 2011

Pretende-se abordar a importância da noção de estrutura no campo psicanalítico, considerando sua pertinência nas formulações freudianas e seus destinos no percurso teórico de Lacan. O termo estrutura encontra-se implícito na obra de Freud no que tange à importância do diagnóstico diferencial. Lacan se propôs a reler Freud a partir do estruturalismo a fim de reconduzir a experiência psicanalítica à fala e à linguagem. Ressaltaremos duas divergências que marcam o afastamento incondicional de Lacan do movimento estruturalista: a concepção do sujeito e o registro do real.
De semelhança a semelhança
Authors: Didi-Huberman Georges
Published: December 2011

O artigo analisa a imagem e a semelhança como condições essenciais na experiência literária de Maurice Blanchot, discutindo, a partir de várias obras do escritor, as relações entre linguagem e imagem. Trabalha-se em especial a noção de "meio absoluto", invocada por Blanchot para descrever o devir-imagem da linguagem na literatura.
Obsessões e desvarios na obra de Veronica Stigger
Authors: Dias Angela Maria
Published: December 2011

A interpretação de alguns contos de Veronica Stigger, a partir de componentes obsessivas e destemperadas, na constituição dos personagens e das tramas simples e minimalistas, conduz a presente reflexão a constatar, no estilo da autora, uma tentativa de conciliação entre uma estética de influência expressionista e o modo melodramático. Em seus códigos enfáticos e na compartilhada tendência à forma paradoxal do "extático paroxismo", em que maneiras de expressão excessiva desembocam no silêncio e no inexprimível, a crítica aos limites do realismo convencional, inerente ao absurdo neoexpressionista da dicção, convive com a poética do melodrama e dela se reapropria.
O agente comunitário de saúde em angola: desafios para sua atuação e para a formação profissional em saúde
Authors: Pontes Ana Lucia de Moura , Bornstein Vera Joana , Giugliani Camila
Published: December 2011

A experiência brasileira de trabalho e formação de agentes comunitários de saúde (ACS) foi a base para a implementação do Programa de Agentes Comunitários de Saúde (Pacs) pela Direção Provincial de Saúde (DPS) de Luanda, em Angola. Esse relato reflete sobre a visita exploratória realizada, em 2009, nos municípios de Cacuaco, Cazenga, Kilamba-Kiaxi, Samba, Sambizanga e Viana, para conhecer as percepções e práticas dos ACS angolanos no que diz respeito ao seu trabalho e à saúde da população. Essa visita pretendia levantar subsídios para a discussão de cooperação técnica entre instituições brasileiras e a coordenação do Pacs da DPS, no sentido de fortalecer a formação de profissionais desse programa. Encontramos semelhanças e diferenças da experiência angolana em relação à brasileira, sendo que consideramos que os principais desafios do caso angolano são: a institucionalização do programa, a regularização do vínculo empregatício e a qualificação profissional dos agentes.
When to Wait for More Evidence? Real Options Analysis in Proton Therapy
Authors: Grutters Janneke P.C. , Abrams Keith R. , de Ruysscher Dirk , Pijls-Johannesma Madelon , Peters Hans J.M. , Beutner Eric , Lambin Philippe , Joore Manuela A.
Published: December 2011

Purpose.

Trends suggest that cancer spending growth will accelerate. One method for controlling costs is to examine whether the benefits of new technologies are worth the extra costs. However, especially new and emerging technologies are often more costly, while limited clinical evidence of superiority is available. In that situation it is often unclear whether to adopt the new technology now, with the risk of investing in a suboptimal therapy, or to wait for more evidence, with the risk of withholding patients their optimal treatment. This trade-off is especially difficult when it is costly to reverse the decision to adopt a technology, as is the case for proton therapy. Real options analysis, a technique originating from financial economics, assists in making this trade-off.

Methods.

We examined whether to adopt proton therapy, as compared to stereotactic body radiotherapy, in the treatment of inoperable stage I non-small cell lung cancer. Three options are available: adopt without further research; adopt and undertake a trial; or delay adoption and undertake a trial. The decision depends on the expected net gain of each option, calculated by subtracting its total costs from its expected benefits.

Results.

In The Netherlands, adopt and trial was found to be the preferred option, with an optimal sample size of 200 patients. Increase of treatment costs abroad and costs of reversal altered the preferred option.

Conclusion.

We have shown that real options analysis provides a transparent method of weighing the costs and benefits of adopting and/or further researching new and expensive technologies.
Prediction of cover crack propagation in RC structures caused by corrosion
Authors: Chernin Leon , Val Dimitri V. , Stewart Mark G.
Published: December 2011

The paper proposes a model relating the level of reinforcement corrosion (in terms of loss of rebar radius) with the width of corrosion-induced cracks. The model is developed using a simulation of the process of corrosion-induced crack opening by means of finite-element (FE) modelling. Concrete is treated as a linear elastic material, a vertical crack is introduced above a reinforcing bar and expansive behaviour of corrosion products is modelled using a thermal analogy. Corrosion products are divided into those that penetrate (dissipate) into cracks (no crack propagation) and those that cause crack opening. The amount of corrosion products penetrating into cracks at a specified crack width is evaluated using FE modelling and analyses of experimental results. It was found that a corrosion loss of 0·1–0·4 mm dissipated into the cracks when the crack width was 1·0 mm. The influence of geometric parameters such as rebar diameter, spacing and location, and thickness of top and edge concrete covers were investigated. The limits of applicability of the proposed relationships were established using non-linear FE modelling.
Modeling of motor fuel consumption in Serbia, with projection to 2025
Authors: Marinkovic Dalibor , Popovic Zoran , Orlovic Aleksandar , Ristic Mirjana
Published: December 2011

This study is based on the application of mathematical methods of statistical
analysis that can be used to predict the development of motor fuel
consumption in the Republic of Serbia. It is based on the linear dependence
of consumption growth of motor fuel from the development of gross domestic
product per capita, which is then corrected by introducing five additional
influencing parameters. The model results indicate that the total
consumption of motor fuels in Serbia from 2010 to 2025 will be increased by
26.5%. Individual consumption of motor fuels shows different market
tendencies. Diesel fuel consumption expects to continue intensive growth to
2025, even though slightly slower than the achievements in the last decade.
The current trend of declining demand for gasoline will be stopped from
2014-2015, then followed by slow growth of demand by 2025. Consumption of
liquefied petroleum gasses (LPG) will at about 2014 to enter the phase of
saturation.
The electrocatalytic properties of carbon supported PtRu/C nanoalloys in oxidation of small organic molecules: Comparison with Pt/C catalyst
Authors: Lovic Jelena , Popovic Ksenija , Tripkovic Amalija
Published: December 2011

The electrocatalytic activity of carbon supported PtRu/C catalysts, with
different composition, toward the electrooxidation of methanol, CO and
formic acid were examined in acid and alkaline solution at ambient
temperature using thin-film rotating disk electrode (RDE) method and
compared with activity of Pt/C. The catalysts were characterized by XRD, AFM
and STM techniques. XRD pattern revealed that PtRu-1/C catalyst is consisted
of two structures e.g. Pt-Ru-fcc and Ru-hcp (the solid solution of Ru in Pt
and the small amount of Ru or solid solution of Pt in Ru), as opposed to
PtRu-2/C catalyst which is consisted of one structure mostly, Pt-Ru-fcc.
According to STM images, PtRu as well as Pt, particles size were between 2
and 6 nm, which is in a good agreement with the mean particles size
determined by XRD. To establish the activity and stability of the catalysts
potentiodynamic and quasi steady-state measurements were performed. It was
found that the activity of Pt and PtRu for CO and methanol oxidation is a
strong function of pH of solution. The kinetics are much higher in alkaline
than in acid solution and the difference between Pt/C and PtRu/C is much
less pronounced in alkaline media. Results presented in this work indicate
that activity of PtRu catalysts depends on catalyst composition, e.g. on
Pt/Ru atomic ratio, as well as on alloying degree of catalysts. Comparison
of CO, methanol and formic acid oxidation on PtRu-2/C, PtRu-1/C and Pt/C
catalysts revealed that PtRu-2/C is the most active one. It was shown that
the PtRu-2/C catalyst, due to fact that it is consisted of only one phase,
with high alloying degree, through the bifunctional mechanism improved by
electronic effect, achieve the activity two times higher related to PtRu-1/C
in the oxidation of all organic molecules investigated, and about three
times higher compared to Pt/C in the oxidation of methanol and CO, and five
times higher in formic acid oxidation.
Nanomolar determination of Pb (II) ions by selective templated electrode
Authors: Mazloum-Ardakani Mohammad , Amini Mohammad , Dehghan Marzieh , Kordi Elham , Sheikh-Mohseni Mohammad
Published: December 2011

Polypyrrole modified electrode, prepared by electropolymerization of pyrrole
in the presence of methyl red as a dopant, was templated with respect to
Pb2+ ion and applied for potentiometric and voltammetric detection of this
ion. The templating process improved the analytical response characteristics
of the electrode, specially their selectivity, with respect to Pb2+ ion. The
improvement depends on both the incorporated ligand (dopant) and the
templating process, with the latter being more vital. The potentiometric
response of the electrode was linear within the Pb2+ concentration range of
2.0?10-6 to 5.0?10-2 M with a near-Nernstian slope of 28.6 mV decade-1 and a
detection limit of 7.0 ?10-7 M. The electrode was also used for
preconcentration differential pulse anodic stripping voltammetry (DPASV) and
results showed that peak currents for the incorporated lead species were
dependent on the metal ion concentration in the range of 1.0?10-8 to
1.0?10-3 M. The detection limit of DPASV method was 3.5 ?10-9 M. The
selectivity of the electrode with respect to some transition metal ions was
investigated. The modified-templated electrode was used for the successful
assay of lead in two standard reference material samples.
From Student to Accounting Professional: A Longitudinal Study of the Filtering Process
Authors: Swain Monte R. , Olsen Kari Joseph
Published: December 2011

Over a 15-year period, we observe the pattern of personality types of students that come into introductory accounting classes, into the accounting major, into the accounting profession, and that remain in accounting as a long-term career. While most research has concentrated on either education or professional careers, our study represents perhaps the first significant longitudinal study employing a within-subject design to examine both the accounting education decision, and the decision to pursue and remain with an accounting career. By employing mediational analysis techniques, our study examines the filtering process that leads to the personality makeup of practicing accountants. Our analysis extends beyond descriptive correlations of MBTI personality types majoring in accounting to provide evidence of how MBTI personality type preferences influence career decisions through mediated measures of attitude, intent, and performance. In particular, we demonstrate clearly both the nature and the preponderance of personality types in both the accounting major and accounting profession who prefer gathering information based on observations of concrete data versus gathering insight based on an intuitive exploration of meanings and relationships—classified in the MBTI personality literature as Sensors versus Intuitors, respectively.

Data Availability: Data available upon request.