bluuebunny/crossref_metadata_2025 huggingface dataset:
Rapid mapping of visual receptive fields by filtered back projection: application to multi‐neuronal electrophysiology and imaging
Authors: Johnston Jamie , Ding Huayu , Seibel Sofie H. , Esposti Federico , Lagnado Leon
Published: August 2014

Key points

To understand vision, we must measure the spatio‐temporal receptive field of neurons in the visual system.

We describe how the filtered back projection can be used to map the receptive fields of many neurons simultaneously, within a few minutes.

This method can also reveal complex features of visual receptive fields such as the tuning of orientation selective neurons and the contributions from separate ON and OFF components.

We demonstrate that the filtered back projection is suited to mapping receptive fields from populations of neurons recorded with imaging or electrophysiology and should therefore prove useful for investigations of visual processing throughout the visual pathway.

Neurons in the visual system vary widely in the spatiotemporal properties of their receptive fields (RFs), and understanding these variations is key to elucidating how visual information is processed. We present a new approach for mapping RFs based on the filtered back projection (FBP), an algorithm used for tomographic reconstructions. To estimate RFs, a series of bars were flashed across the retina at pseudo‐random positions and at a minimum of five orientations. We apply this method to retinal neurons and show that it can accurately recover the spatial RF and impulse response of ganglion cells recorded on a multi‐electrode array. We also demonstrate its utility forin vivoimaging by mapping the RFs of an array of bipolar cell synapses expressing a genetically encoded Ca2+indicator. We find that FBP offers several advantages over the commonly used spike‐triggered average (STA): (i) ON and OFF components of a RF can be separated; (ii) the impulse response can be reconstructed at sample rates of 125 Hz, rather than the refresh rate of a monitor; (iii) FBP reveals the response properties of neurons that are not evident using STA, including those that display orientation selectivity, or fire at low mean spike rates; and (iv) the FBP method is fast, allowing the RFs of all the bipolar cell synaptic terminals in a field of view to be reconstructed in under 4 min. Use of the FBP will benefit investigations of the visual system that employ electrophysiology or optical reporters to measure activity across populations of neurons.
Wiring patterns in the mouse retina: collecting evidence across the connectome, physiology and light microscopy
Authors: Dunn Felice A. , Wong Rachel O. L.
Published: August 2014

The visual system has often been thought of as a parallel processor because distinct regions of the brain process different features of visual information. However, increasing evidence for convergence and divergence of circuit connections, even at the level of the retina where visual information is first processed, chips away at a model of dedicated and distinct pathways for parallel information flow. Instead, our current understanding is that parallel channels may emerge, not from exclusive microcircuits for each channel, but from unique combinations of microcircuits. This review depicts diagrammatically the current knowledge and remaining puzzles about the retinal circuit with a focus on the mouse retina. Advances in techniques for labelling cells and genetic manipulations have popularized the use of transgenic mice. We summarize evidence gained from serial electron microscopy, electrophysiology and light microscopy to illustrate the wiring patterns in mouse retina. We emphasize the need to explore proposed retinal connectivity using multiple methods to verify circuits both structurally and functionally.
Ionotropic GABA and glycine receptor subunit composition in human pluripotent stem cell‐derived excitatory cortical neurones
Authors: James Owain T. , Livesey Matthew R. , Qiu Jing , Dando Owen , Bilican Bilada , Haghi Ghazal , Rajan Rinku , Burr Karen , Hardingham Giles E. , Chandran Siddharthan , Kind Peter C. , Wyllie David J. A.
Published: August 2014

Key points

This study reports a functional assessment of the subunit composition of inhibitory ionotropic GABAA receptors (GABAARs) and glycine receptors (GlyRs) expressed by excitatory cortical neurones derived from human embryonic stem cells (hECNs).

GABAARs expressed by hECNs are predominantly composed of α2/3β3γ2 subunits; such a composition is typical of that reported for GABAARs expressed in rodent embryonic cortex.

Analysis of GlyRs expressed by hECNs indicates they are likely to contain α2 and β subunits – a composition in rodents that is associated with a late embryonic/early postnatal period of development.

We have assessed, using whole‐cell patch‐clamp recording and RNA‐sequencing (RNA‐seq), the properties and composition of GABAA receptors (GABAARs) and strychnine‐sensitive glycine receptors (GlyRs) expressed by excitatory cortical neurons derived from human embryonic stem cells (hECNs). The agonists GABA and muscimol gave EC50 values of 278 μm and 182 μm, respectively, and the presence of a GABAAR population displaying low agonist potencies is supported by strong RNA‐seq signals for α2 and α3 subunits. GABAAR‐mediated currents, evoked by EC50 concentrations of GABA, were blocked by bicuculline and picrotoxin with IC50 values of 2.7 and 5.1 μm, respectively. hECN GABAARs are predominantly γ subunit‐containing as assessed by the sensitivity of GABA‐evoked currents to diazepam and insensitivity to Zn2+, together with the weak direct agonist action of gaboxadol; RNA‐seq indicated a predominant expression of the γ2 subunit. Potentiation of GABA‐evoked currents by propofol and etomidate and the lack of inhibition of currents by salicylidine salycylhydrazide (SCS) indicate expression of the β2 or β3 subunit, with RNA‐seq analysis indicating strong expression of β3 in hECN GABAARs. Taken together our data support the notion that hECN GABAARs have an α2/3β3γ2 subunit composition – a composition that also predominates in immature rodent cortex. GlyRs expressed by hECNs were activated by glycine with an EC50 of 167 μm. Glycine‐evoked (500 μm) currents were blocked by strychnine (IC50 = 630 nm) and picrotoxin (IC50 = 197 μm), where the latter is suggestive of a population of heteromeric receptors. RNA‐seq indicates GlyRs are likely to be composed of α2 and β subunits.
Angiotensin II mobilizes intracellular calcium and activates pannexin‐1 channels in rat carotid body type II cells via AT1 receptors
Authors: Murali Sindhubarathi , Zhang Min , Nurse Colin A.
Published: August 2014

Key points

A locally generating, angiotensin II (ANG II) system is present in the rat carotid body (CB) and up‐regulation of this system occurs in certain pathophysiological situations, enhancing sympathetic activity.

Here, we show that, similar to chemoreceptor type I cells, glial‐like type II cells also express functional AT1Rs, stimulation of which causes release of Ca2+ from intracellular stores.

ANG II–AT1R signalling in type II cells activates an inward current carried by pannexin‐1 (Panx‐1) channels which are known to act as conduits for release of ATP, a key CB excitatory neurotransmitter.

Combined effects of ANG II and ATP, which also activates Panx‐1 currents via P2Y2 receptors, were synergistic; chelating intracellular Ca2+ with BAPTA prevented Panx‐1 current activation.

We propose that the excitatory function of ANG II in the CB involves dual actions at both type I and type II cells.

A local angiotensin‐generating system is present in the carotid body (CB) and increased angiotensin II (ANG II) signalling contributes to enhanced CB excitation in chronic heart failure (CHF) and after chronic or intermittent hypoxia. ANG II actions have thus far been attributed solely to stimulation of AT1 receptors (AT1Rs) on chemoreceptor type I cells. Here, we show that in dissociated rat CB cultures, ANG II also stimulates glial‐like type II cells, identified by P2Y2‐receptor‐induced intracellular Ca2+ elevation (Δ[Ca2+]i). ANG II induced a dose‐dependent (EC50 ∼8 nm), robust Δ[Ca2+]i in type II cells that was reversibly abolished by the AT1R blocker losartan (1 μm). The ANG II‐induced Δ[Ca2+]i persisted in Ca2+‐free medium but was sensitive to store depletion with cyclopiazonic acid (1 μm). Similar to P2Y2 receptor agonists, ANG II (20–1000 nm) activated pannexin‐1 (Panx‐1) current that was reversibly abolished by carbenoxolone (5 μm). This current arose with a variable delay and was reversibly inhibited by losartan. Repeated application of ANG II often led to current run‐down, attributable to AT1R desensitization. When applied to the same cell the combined actions of ANG II and ATP on Panx‐1 current were synergistic. Current induced by either ligand was inhibited by BAPTA‐AM (1 μm), suggesting that intracellular Ca2+ signalling contributed to Panx‐1 channel activation. Because open Panx‐1 channels release ATP, a key CB excitatory neurotransmitter, it is plausible that paracrine stimulation of type II cells by ANG II contributes to enhanced CB excitability, especially in pathophysiological conditions such as CHF and sleep apnoea.
A Generic Modelling of Fire Impact in a Tree-Grass Savanna Model
Authors: Tchuinte Alexis Tamen , Tewa Jean-Jules , Couteron Pierre , Bowong Samuel , Dumont Yves
Published: August 2014

We propose and study a model for tree-grass interactions in the context of savannas which are subjected to fire pressure. Several theoretical models in the literature which have highlighted the impact of fire on tree-grass interactions did not explicitly deal with the indirect feedback of dry grass biomass onto tree dynamics through fire intensity and frequency. The novelty in our work is to consider a fairly generic modeling of fire impact on woody biomass by means of a family of increasing and bounded functions of grass biomass. The characteristic feature of this family of functions is that, it could include several forms: linear as well as non-linear ones (sigmoidal or not). Since the nonlinear shape brings more diverse results than the previous attempts using a linear function, it could be used to show that several vegetation equilibria exist with some of them showing tree-grass coexistence features.We show that the number of equilibria with both grass and trees depends on the choice of the fire impact function. We also established thresholds defining the stability domains of the equilibria and highlighted some bifurcation parameters to provide numerical simulations complying with the theoretical properties of the model.
Mixed Boundary Layer Skin Friction and Heat Transfer With Abrupt Transition
Authors: Brewster M. Q.
Published: August 2014

In the form that is commonly published in introductory textbooks, the classical problem of skin friction and heat transfer for a mixed laminar–turbulent boundary-layer flow on a flat-plate with an abrupt transition is nonconservative in mass, momentum, and energy. By forcing continuity in momentum and enthalpy thicknesses, the textbook problem takes on the appearance of conserving momentum and energy. But, by doing so while retaining a turbulent virtual origin at the plate's leading edge, the textbook example omits necessary jumps in these quantities and violates conservation of mass, momentum, and energy in the flow. Here we modify this classical problem to satisfy conservation principles through the introduction of either concentrated mass/momentum/energy fluxes, at the top of the boundary layer and/or concentrated surface shear stress/heat fluxes at the bottom. Out of this simple analysis comes the intriguing idea of an entrainment flux or inflow at the top of the boundary layer over the transition region.
Development of Scallop Cut Type Damper Seal for Centrifugal Compressors
Authors: Takahashi Naohiko , Miura Haruo , Narita Mitsuhiro , Nishijima Noriyo , Magara Yohei
Published: August 2014

This paper deals with a new type of damper seal developed for a high-pressure centrifugal compressor. Honeycomb seals and hole pattern seals are popularly used as damper seals and provide superior rotordynamic damping characteristics. Honeycomb seals are expensive because the manufacturing process is complex. Hole pattern seals are easier to manufacture, but they are still expensive. Use of a scallop pattern is one way to reduce manufacturing cost and time. A new seal that has a scallop pattern and small teeth on the stator surface is proposed. This pattern is cut on the stator surface using a disk type tool. To estimate the rotordynamic coefficients of this new seal, a bulk flow model code that is based on a two-control-volume model developed by Matsuda for labyrinth seals was newly developed. This model uses the Hirs model for the viscous shear stresses. The friction factor coefficients for the rotor surface, the stator surface, and the surface between the two-control-volumes were determined by computational fluid dynamics (CFD) steady analysis. The rotordynamic coefficients can also be obtained by using CFD perturbation analysis. The high accuracy of the bulk flow model was demonstrated by comparing its results with CFD perturbation analysis results. In the perturbation analysis, the whirling motion was treated as a steady-state problem by using a rotating frame of reference. For the damper seal, the rotor surface and its neighboring region were treated with a rotating frame of reference and the neighboring region of the stator was treated with a stationary frame of reference. The damping property of the new seal was evaluated by conducting rotor stability tests using a high-pressure compressor with an electromagnetic exciter. The new seal equipped with swirl brakes was used for the balance piston of the compressor. Stability was evaluated by exciting the rotor during operation and identifying the eigenvalues of the rotor. The experimental results showed that the new seal increases damping. Comparison of the damping effect with calculations based on the bulk flow analysis showed good agreement.
Tilting-Pad Journal Bearings With Active Lubrication Applied as Calibrated Shakers: Theory and Experiment
Authors: Varela Alejandro Cerda , Santos Ilmar Ferreira
Published: August 2014

In recent years, a continuous research effort has transformed the conventional tilting-pad journal bearing (TPJB) into a mechatronic machine element. The addition of electromechanical elements provides the possibility of generating controllable forces over the rotor as a function of a suitable control signal. Such forces can be applied in order to perform parameter identification procedures “in situ,” which enables evaluation of the mechanical condition of the machine in a noninvasive way. The usage of a controllable bearing as a calibrated shaker requires obtaining the bearing specific frequency dependent calibration function, i.e., the transfer function between control signal and force over the rotor. This work presents a theoretical model of the calibration function for a TPJB with active lubrication. The bearing generates controllable forces by injecting pressurized oil directly into the bearing clearance. The injected flow is controlled by means of a servovalve. The theoretical model includes the dynamics of the hydraulic system using a lumped parameter approach, which is coupled with the bearing oil film using a modified form of the Reynolds equation. The oil film model is formulated considering an elastothermohydrodynamic lubrication regime. New contributions to the mathematical modeling are presented, such as the inclusion of the dynamics of the hydraulic pipelines and the obtention of the bearing calibration function by means of harmonic analysis of a linearized form of the controllable bearing constitutive equations. The mathematical model is used to study the relevance and effects of different parameters on the calibration function, aiming at providing general guidelines for the active bearing design. Finally, experimental results regarding the calibration function and the usage of the studied bearing as a calibrated shaker provide insight into the possibilities of application of this technology.
Comparison of the Aerodynamics of Acoustically Designed Exit Guide Vanes and a State-of-the-Art Exit Guide Vane
Authors: Marn Andreas , Broszat Dominik , Selic Thorsten , Schönleitner Florian , Heitmeir Franz
Published: August 2014

Within previous EU projects, possible modifications to the engine architecture have been investigated, which would allow for an optimized aerodynamic or acoustic design of the exit guide vanes (EGVs) of the turbine exit casing (TEC). However, the engine weight should not be increased and the aerodynamic performance must be at least the same. This paper compares a state-of-the art TEC (reference TEC) with typical EGVs with an acoustically optimized TEC configuration for the engine operating point approach. It is shown that a reduction in sound power level for the fundamental tone (one blade passing frequency (BPF)) for this acoustically important operating point can be achieved. It is also shown that the weight of the acoustically optimized EGVs (only bladings considered) is almost equal to the reference TEC, but a reduction in engine length can be achieved. Measurements were conducted in the subsonic test turbine facility (STTF) at the Institute for Thermal Turbomachinery and Machine Dynamics, Graz University of Technology. The inlet guide vanes (IGVs), the low pressure turbine (LPT) stage, and the EGVs have been designed by MTU Aero Engines.
Investigation of Hydrogen Enriched Natural Gas Flames in a SGT-700/800 Burner Using OH PLIF and Chemiluminescence Imaging
Authors: Lantz Andreas , Collin Robert , Aldén Marcus , Lindholm Annika , Larfeldt Jenny , Lörstad Daniel
Published: August 2014

The effect of hydrogen enrichment to natural gas flames was experimentally investigated at atmospheric pressure conditions using flame chemiluminescence imaging, planar laser-induced fluorescence of hydroxyl radicals (OH PLIF), and dynamic pressure monitoring. The experiments were performed using a third generation dry low emission (DLE) burner used in both SGT-700 and SGT-800 industrial gas turbines from Siemens. The burner was mounted in an atmospheric combustion test rig at Siemens with optical access in the flame region. Four different hydrogen enriched natural gas flames were investigated; 0 vol. %, 30 vol. %, 60 vol. %, and 80 vol. % of hydrogen. The results from flame chemiluminescence imaging and OH PLIF show that the size and shape of the flame was clearly affected by hydrogen addition. The flame becomes shorter and narrower when the amount of hydrogen is increased. For the 60 vol. % and 80 vol. % hydrogen flames the flame has moved upstream and the central recirculation zone that anchors the flame has moved upstream the burner exit. Furthermore, the position of the flame front fluctuated more for the full premixed flame with only natural gas as fuel than for the hydrogen enriched flames. Measurements of pressure drop over the burner show an increase with increased hydrogen in the natural gas despite same air flow thus confirming the observation that the flame front moves upstream toward the burner exit and thereby increasing the blockage of the exit. Dynamic pressure measurements in the combustion chamber wall confirms that small amounts of hydrogen in natural gas changes the amplitude of the dynamic pressure fluctuations and initially dampens the axial mode but at higher levels of hydrogen an enhancement of a transversal mode in the combustion chamber at higher frequencies could occur.
Scalable control program for multiprecursor flow-type atomic layer deposition system
Authors: Selvaraj Sathees Kannan , Takoudis Christos G.
Published: August 2014

The authors report the development and implementation of a scalable control program to control flow type atomic layer deposition (ALD) reactor with multiple precursor delivery lines. The program logic is written and tested in labview environment to control ALD reactor with four precursor delivery lines to deposit up to four layers of different materials in cyclic manner. The programming logic is conceived such that to facilitate scale up for depositing more layers with multiple precursors and scale down for using single layer with any one precursor in the ALD reactor. The program takes precursor and oxidizer exposure and purging times as input and controls the sequential opening and closing of the valves to facilitate the complex ALD process in cyclic manner. The program could be used to deposit materials from any single line or in tandem with other lines in any combination and in any sequence.
Potential for reactive pulsed-dc magnetron sputtering of nanocomposite VOx microbolometer thin films
Authors: Jin Yao O. , Ozcelik Adem , Horn Mark W. , Jackson Thomas N.
Published: August 2014

Vanadium oxide (VOx) thin films were deposited by reactive pulsed-dc sputtering a metallic vanadium target in argon/oxygen mixtures with substrate bias. Hysteretic oxidation of the vanadium target surface was assessed by measuring the average cathode current during deposition. Nonuniform oxidization of the target surface was analyzed by Raman spectroscopy. The VOx film deposition rate, resistivity, and temperature coefficient of resistance were correlated to oxygen to argon ratio, processing pressure, target-to-substrate distance, and oxygen inlet positions. To deposit VOx in the resistivity range of 0.1–10 Ω-cm with good uniformity and process control, lower processing pressure, larger target-to-substrate distance, and oxygen inlet near the substrate are useful.
Consistency of Commercial Devices for Measuring Elevation Gain
Authors: Menaspà Paolo , Impellizzeri Franco M. , Haakonssen Eric C. , Martin David T. , Abbiss Chris R.
Published: August 2014

Purpose:

To determine the consistency of commercially available devices used for measuring elevation gain in outdoor activities and sports.

Methods:

Two separate observational validation studies were conducted. Garmin (Forerunner 310XT, Edge 500, Edge 750, and Edge 800; with and without elevation correction) and SRM (Power Control 7) devices were used to measure total elevation gain (TEG) over a 15.7-km mountain climb performed on 6 separate occasions (6 devices; study 1) and during a 138-km cycling event (164 devices; study 2).

Results:

TEG was significantly different between the Garmin and SRM devices (P < .05). The between-devices variability in TEG was lower when measured with the SRM than with the Garmin devices (study 1: 0.2% and 1.5%, respectively). The use of the Garmin elevation-correction option resulted in a 5–10% increase in the TEG.

Conclusions:

While measurements of TEG were relatively consistent within each brand, the measurements differed between the SRM and Garmin devices by as much as 3%. Caution should be taken when comparing elevation-gain data recorded with different settings or with devices of different brands.
Accuracy of Indirect Estimation of Power Output From Uphill Performance in Cycling
Authors: Millet Grégoire P. , Tronche Cyrille , Grappe Frédéric
Published: August 2014

Purpose:

To use measurement by cycling power meters (Pmes) to evaluate the accuracy of commonly used models for estimating uphill cycling power (Pest). Experiments were designed to explore the influence of wind speed and steepness of climb on accuracy of Pest. The authors hypothesized that the random error in Pest would be largely influenced by the windy conditions, the bias would be diminished in steeper climbs, and windy conditions would induce larger bias in Pest.

Methods:

Sixteen well-trained cyclists performed 15 uphill-cycling trials (range: length 1.3–6.3 km, slope 4.4–10.7%) in a random order. Trials included different riding position in a group (lead or follow) and different wind speeds. Pmes was quantified using a power meter, and Pest was calculated with a methodology used by journalists reporting on the Tour de France.

Results:

Overall, the difference between Pmes and Pest was –0.95% (95%CI: –10.4%, +8.5%) for all trials and 0.24% (–6.1%, +6.6%) in conditions without wind (>2 m/s). The relationship between percent slope and the error between Pest and Pmes were considered trivial.

Conclusions:

Aerodynamic drag (affected by wind velocity and orientation, frontal area, drafting, and speed) is the most confounding factor. The mean estimated values are close to the power-output values measured by power meters, but the random error is between ±6% and ±10%. Moreover, at the power outputs (>400 W) produced by professional riders, this error is likely to be higher. This observation calls into question the validity of releasing individual values without reporting the range of random errors.
Neuromuscular Electrical Stimulation: No Enhancement of Recovery From Maximal Exercise
Authors: Malone John K. , Blake Catherine , Caulfield Brian
Published: August 2014

Purpose:

To investigate the use of neuromuscular electrical stimulation (NMES) during acute recovery between 2 bouts of maximal aerobic exercise.

Methods:

On 3 separate days, 19 trained male cyclists (28 ± 7 y, 76.4 ± 10.4 kg, power output at maximal aerobic power [pVo2max] 417 ± 44 W) performed a 3-min maximal cycling bout at 105% PVo2max before a 30-min randomly assigned recovery intervention of passive (PAS: resting), active (ACT: 30% PVo2max), or NMES (5 Hz, 4 pulses at 500 μs). Immediately afterward, a cycle bout at 95% PVo2max to exhaustion (TLIM) was performed. Heart rate (HR) and blood lactate (BLa) were recorded at designated time points. Data were analyzed using repeated-measures ANOVA with a Tukey honestly significantly different post hoc test. Statistical significance threshold was P < .05.

Results:

The TLIM was significantly shorter for NMES than for ACT (199.6 ± 69.4 s vs 250.7 ± 105.5 s: P = .016) but not PAS recovery (199.6 ± 69.4 s vs 216.4 ± 77.5 s: P = .157). The TLIM was not significantly different between ACT and PAS (250.7 ± 105.5 s vs 216.4 ± 77.5 s: P = .088). The decline in BLa was significantly greater during ACT than NMES and PAS recovery (P < .001), with no difference between NMES and PAS. In addition, HR was significantly higher during ACT than NMES and PAS recovery (P < .001), with no difference between NMES and PAS.

Conclusions:

NMES was less effective than ACT and comparable to PAS recovery when used between 2 bouts of maximal aerobic exercise in trained male cyclists.
Comparison of Athlete–Coach Perceptions of Internal and External Load Markers for Elite Junior Tennis Training
Authors: Murphy Alistair P. , Duffield Rob , Kellett Aaron , Reid Machar
Published: August 2014

Purpose:

To investigate the discrepancy between coach and athlete perceptions of internal load and notational analysis of external load in elite junior tennis.

Methods:

Fourteen elite junior tennis players and 6 international coaches were recruited. Ratings of perceived exertion (RPEs) were recorded for individual drills and whole sessions, along with a rating of mental exertion, coach rating of intended session exertion, and athlete heart rate (HR). Furthermore, total stroke count and unforced-error count were notated using video coding after each session, alongside coach and athlete estimations of shots and errors made. Finally, regression analyses explained the variance in the criterion variables of athlete and coach RPE.

Results:

Repeated-measures analyses of variance and interclass correlation coefficients revealed that coaches significantly (P < .01) underestimated athlete session RPE, with only moderate correlation (r = .59) demonstrated between coach and athlete. However, athlete drill RPE (P = .14; r = .71) and mental exertion (P = .44; r = .68) were comparable and substantially correlated. No significant differences in estimated stroke count were evident between athlete and coach (P = .21), athlete notational analysis (P = .06), or coach notational analysis (P = .49). Coaches estimated significantly greater unforced errors than either athletes or notational analysis (P < .01). Regression analyses found that 54.5% of variance in coach RPE was explained by intended session exertion and coach drill RPE, while drill RPE and peak HR explained 45.3% of the variance in athlete session RPE.

Conclusion:

Coaches misinterpreted session RPE but not drill RPE, while inaccurately monitoring error counts. Improved understanding of external- and internal-load monitoring may help coach–athlete relationships in individual sports like tennis avoid maladaptive training.
Time to Exhaustion at Continuous and Intermittent Maximal Lactate Steady State During Running Exercise
Authors: Dittrich Naiandra , de Lucas Ricardo Dantas , Beneke Ralph , Antonacci Guglielmo Luiz Guilherme
Published: August 2014

The purpose of this study was to determine and compare the time to exhaustion (TE) and the physiological responses at continuous and intermittent (ratio 5:1) maximal lactate steady state (MLSS) in well-trained runners. Ten athletes (32.7 ± 6.9 y, VO2max 61.7 ± 3.9 mL · kg−1 · min−1) performed an incremental treadmill test, three to five 30-min constant-speed tests to determine the MLSS continuous and intermittent (5 min of running, interspaced by 1 min of passive rest), and 2 randomized TE tests at such intensities. Two-way ANOVA with repeated measures was used to compare the changes in physiological variables during the TE tests and between continuous and intermittent exercise. The intermittent MLSS velocity (MLSSint = 15.26 ± 0.97 km/h) was higher than in the continuous model (MLSScon = 14.53 ± 0.93 km/h), while the TE at MLSScon was longer than MLSSint (68 ± 11 min and 58 ± 15 min, P < .05). Regarding the cardiorespiratory responses, VO2 and respiratory-exchange ratio remained stable during both TE tests while heart rate, ventilation, and rating of perceived exertion presented a significant increase in the last portion of the tests. The results showed a higher tolerance to exercising during MLSScon than during MLSSint in trained runners. Thus, the training volume of an extensive interval session (ratio 5:1) designed at MLSS intensity should take into consideration this higher speed at MLSS and also the lower TE than with continuous exercise.
Publication bias in the social sciences: Unlocking the file drawer
Authors: Franco Annie , Malhotra Neil , Simonovits Gabor
Published: August 2014

The file drawer is full. Should we worry?

Experiments that produce null results face a higher barrier to publication than those that yield statistically significant differences. Whether this is a problem depends on how many null but otherwise valid results might be trapped in the file drawer. Franco
et al.
use a Time-sharing Experiments in the Social Sciences archive of nearly 250 peer-reviewed proposals of social science experiments conducted on nationally representative samples. They find that only 10 out of 48 null results were published, whereas 56 out of 91 studies with strongly significant results made it into a journal.

Science
, this issue p.
1502
A local macrophage chemokine network sustains protective tissue-resident memory CD4 T cells
Authors: Iijima Norifumi , Iwasaki Akiko
Published: August 2014

Resident memory T cells sound the alarm

Immunological memory protects against reinfection. Resident memory T cells (T
RM
) are long-lived and remain in the tissues where they first encountered a pathogen (see the Perspective by Carbone and Gebhardt). Schenkel
et al.
and Ariotti
et al.
found that CD8
+
T
RM
cells act like first responders in the female reproductive tissue or the skin of mice upon antigen reencounter. By secreting inflammatory proteins, T
RM
cells rapidly activated local immune cells to respond, so much so that they protected against infection with an unrelated pathogen. Iijima and Iwasaki found that CD4
+
T
RM
cells protected mice against reinfection with intravaginal herpes simplex virus 2.

Science
, this issue p.
98
, p.
101
, p.
93
; see also p.
40
Draft Genome Sequence of the Fish Pathogen Yersinia ruckeri Strain 37551, Serotype O1b, Isolated from Diseased, Vaccinated Atlantic Salmon (
Salmo salar
) in Chile
Authors: Navas Esteban , Bohle Harry , Henríquez Patricio , Grothusen Horst , Bustamante Fernando , Bustos Patricio , Mancilla Marcos
Published: August 2014

We sequenced the genome of a motile O1b
Yersinia ruckeri
field isolate from Chile, which is causing enteric redmouth disease (ERM) in vaccinated Atlantic salmon (
Salmo salar
). The draft genome has 3,775,486 bp, a G+C content of 47.1%, and is predicted to contain 3,406 coding sequences.
How does under-reporting of negative and inconclusive results affect the false-positive rate in meta-analysis? A simulation study
Authors: Kicinski Michal
Published: August 2014

Objective

To investigate the impact of a higher publishing probability for statistically significant positive outcomes on the false-positive rate in meta-analysis.

Design

Meta-analyses of different sizes (N=10, N=20, N=50 and N=100), levels of heterogeneity and levels of publication bias were simulated.

Primary and secondary outcome measures

The type I error rate for the test of the mean effect size (ie, the rate at which the meta-analyses showed that the mean effect differed from 0 when it in fact equalled 0) was estimated. Additionally, the power and type I error rate of publication bias detection methods based on the funnel plot were estimated.

Results

In the presence of a publication bias characterised by a higher probability of including statistically significant positive results, the meta-analyses frequently concluded that the mean effect size differed from zero when it actually equalled zero. The magnitude of the effect of publication bias increased with an increasing number of studies and between-study variability. A higher probability of including statistically significant positive outcomes introduced little asymmetry to the funnel plot. A publication bias of a sufficient magnitude to frequently overturn the meta-analytic conclusions was difficult to detect by publication bias tests based on the funnel plot. When statistically significant positive results were four times more likely to be included than other outcomes and a large between-study variability was present, more than 90% of the meta-analyses of 50 and 100 studies wrongly showed that the mean effect size differed from zero. In the same scenario, publication bias tests based on the funnel plot detected the bias at rates not exceeding 15%.

Conclusions

This study adds to the evidence that publication bias is a major threat to the validity of medical research and supports the usefulness of efforts to limit publication bias.
Accidents and injuries related to powered paragliding: a cross-sectional study
Authors: Feletti Francesco , Goin Jeff
Published: August 2014

Objectives

Powered paragliding (PPG) and paragliding are two totally different sports, mainly because of the use of an engine in powered paragliding. As a consequence, the pattern of injuries caused by each of these two sports may be different.

Setting

To test this hypothesis, we analysed 384 incident reports gathered by the US Powered Paragliding Association from 1995 to 2012. The majority of the incidents occurred in the USA, while 26 incidents occurred elsewhere: Canada (8), Mexico (5), Panama (1), China (1), Japan (1), Malaysia (1), Indonesia (Java) (1), Europe (8): of which Spain (1), Belgium (1), UK (3), Italy (1), Romania (1), unknown (1).

Outcome

To identify the most affected body area and the most common type of injury sustained in PPG, and to highlight any differences from paragliding.

Results

The most affected body areas in PPG were the upper limbs (44.5%), followed by the lower limbs (32%), the back (9.8%), the head (7%), the pelvis (3.1), the chest (2.7%) and the abdomen (0.7%) (p<0.001). The engine caused 43 accidents (11.2%) in our study and was responsible for the majority of injuries to the upper limbs. The number of fatal accidents in PPG is not lower than in paragliding and hang-gliding.

Conclusions

To help prevent the specific injuries of PPG, the most appropriate equipment should be identified. The results of this study also suggest that, in the future, this sport should be analysed separately from paragliding.
Prevalence and risk factors for chronic co-infection in pulmonaryMycobacterium aviumcomplex disease
Authors: Fujita Kohei , Ito Yutaka , Hirai Toyohiro , Kubo Takeshi , Togashi Kaori , Ichiyama Satoshi , Mishima Michiaki
Published: August 2014

Background

Patients with pulmonaryMycobacterium aviumcomplex (MAC) disease are often co-infected with various pathogenic microorganisms. This study aimed to determine the prevalence of co-infection with non-MAC pathogens and the risk factors associated with co-infection in patients with pulmonary MAC disease.

Methods

We retrospectively reviewed the patient characteristics, microbiological results and chest CT findings in 275 patients with pulmonary MAC who visited the Kyoto University Hospital from January 2001 to May 2013. We defined chronic pathogenic co-infection as the isolation of non-MAC pathogens from sputum samples taken on more than two visits that occurred at least 3 months apart.

Results

The participants were predominantly female (74.5%) and infected withM. avium(75.6%). Chronic co-infection with any pathogen was observed in 124 patients (45.1%). Methicillin-sensitiveStaphylococcus aureus(MSSA; n=64),Pseudomonas aeruginosa(n=35) andAspergillusspp (n=18) were the most prevalent pathogens. The adjusted factors were chronic obstructive pulmonary disease (COPD; OR=4.2, 95% CI 1.6 to 13.1) and pulmonaryM. intracellularedisease (OR=2.2, 95% CI 1.1 to 4.4) in chronic co-infections; COPD (OR=4.2, 95% CI 2.1 to 31.4), long duration of MAC disease (OR=2.2, 95% CI 1.2 to 4.4) and nodules (OR=3.5, 95% CI 1.2 to 13.2) in chronic MSSA co-infection; COPD (OR=7.5, 95% CI 2.1 to 31.4) and lower lobe involvement (OR=9.9, 95% CI 2.0 to 90.6) in chronicP. aeruginosaco-infection; and use of systemic corticosteroids (OR=7.1, 95% CI 1.2 to 50.9) and pulmonaryM. intracellularedisease (OR=4.0, 95% CI 1.1 to 14.5) in chronicAspergillusspp co-infection.

Conclusions

Patients with pulmonary MAC disease frequently had chronic co-infections with pathogenic microorganisms such as MSSA,P. aeruginosaandAspergillus. The risk factors for chronic co-infection were COPD and pulmonaryM. intracellularedisease.
Prevalence of depressive symptoms and associated socio-demographic factors among recruits during military training
Authors: Zubair Usama Bin , Mansoor S , Rana M H
Published: August 2014

Background

Military training is a stressful and unusual event. It may predispose individuals towards mental health problems. The stress of military training has been shown to result in depressive symptoms that can potentially influence the combat ability of a soldier. This study aimed to determine the prevalence of depressive symptoms among recruits during military training in Northern Pakistan and analyse the associated socio-demographic factors.

Subjects and method

The study was carried out at the Mujahid Force Center, Bhimber, in Azad Jammu and Kashmir (AJK) in the North of Pakistan. This is one of the training institutes of the Pakistan Army. The sample population comprised of 313 adult men undergoing military training at Bhimber AJK. General Health Questionnaire 12 (GHQ-12) was used to screen for any psychiatric illness, and those with a score >4 were administered the Beck Depression Inventory (BDI) to record the presence and severity of depressive symptoms. Age, service type (general duty soldier, cook or clerk), education, level of family income, marital status, tobacco smoking, use of naswar (tobacco based substance), worrying about future and social support status were correlated with depressive symptoms to evaluate the association of these factors with depression in the study population.

Results

Out of 313 recruits screened with GHQ-12, 232 were found to have a score of 4 or more as an indicator of the presence of psychiatric morbidity, and had the BDI administered. Of these 232 recruits, 31.5% had no depressive symptoms, 41.4% had mild, 17.7% had moderate and 9.5% had severe depressive symptoms. With logistic regression, we found significant correlation among depressive symptoms and level of family income, worrying about future and lack of social support.

Conclusions

Prevalence of depressive symptoms was high among recruits. Special attention should be paid to recruits from low socioeconomic background and those who lack social support and who worry about the future.
Standardised clients as assessors in a veterinary communication OSCE: a reliability and validity study
Authors: Artemiou E. , Adams C. L. , Hecker K. G. , Vallevand A. , Violato C. , Coe J. B.
Published: August 2014

In human medicine, standardised patients (SP) have been shown to reliably and accurately assess learners’ communication performance in high‐stakes certification Objective Structured Clinical Examinations (OSCE), offering a feasible way to reduce the need for recruitment, time commitment and coordination of faculty assessors. In this study, we evaluated the use of standardised clients (SC) as a viable option for assessing veterinary students’ communication performance. We designed a four‐station, two‐track communication skills OSCE. SC assessors used an adapted nine‐item Liverpool Undergraduate Communication Assessment Scale (LUCAS). Faculty used a 21‐item checklist derived from the Calgary‐Cambridge Guide (CCG) and a five‐point global rating scale. Participants were second year veterinary students (n=96). For the four stations, intrastation reliability (α) ranged from 0.63 to 0.82 for the LUCAS, and 0.73 to 0.87 for the CCG. The interstation reliability coefficients were 0.85 for the LUCAS and 0.89 for the CGG. The calculated Generalisability (G) coefficients were 0.62 for the LUCAS and 0.60 for the CGG. Supporting construct validity, SC and faculty assessors showed a significant correlation between the LUCAS and CCG total percent scores (r=0.45, P<0.001), and likewise between the LUCAS and global rating scores (r=0.49, P<0.001).Study results support that SC assessors offer a reliable and valid approach for assessing veterinary communication OSCE.
Synthesis of (+)-bovidic acid
Authors: Phillips Geoffrey A. , Wright Timothy B. , Stevens Andrew C. , Pagenkopf Brian L.
Published: August 2014

(+)-Bovidic acid is an 18-carbon hydroxyfuranoid acid isolated from the pelage of the gaur (Bos frontalis) and displays potential as an insect repellant. Both a formal and total synthesis of (+)-bovidic acid was carried out with the core of the natural product being synthesized through Mukaiyama aerobic oxidative cyclization employing the second-generation Co(nmp)2 catalyst.
TENACITY OF TOTAL GRAPHS
Authors: LI YINKUI , WEI ZONGTIAN , YUE XIAOKUI , LIU ERQIANG
Published: August 2014

Communication networks must be constructed to be as stable as possible, not only with the respect to the initial disruption, but also with respect to the possible reconstruction. Many graph theoretical parameters have been used to describe the stability of communication networks. Tenacity is a reasonable one, which shows not only the difficulty to break down the network but also the damage that has been caused. Total graphs are the largest graphs formed by the adjacent relations of elements of a graph. Thus, total graphs are highly recommended for the design of interconnection networks. In this paper, we determine the tenacity of the total graph of a path, cycle and complete bipartite graph, and thus give a lower bound of the tenacity for the total graph of a graph.
A STATISTICAL APPROACH TOWARDS SECURE LOCATION VERIFICATION IN NOISY WIRELESS CHANNELS
Authors: MANDAL PARTHA SARATHI , GHOSH ANIL K.
Published: August 2014

Location verification in wireless sensor networks (WSNs) is quite challenging in the presence of malicious sensor nodes, which are called attackers. These attackers try to break the verification protocol by reporting their incorrect locations during the verification stage. In the literature of WSNs, most of the existing methods of location verification use a set of trusted verifiers, which are vulnerable to attacks by malicious nodes. These existing methods also use some distance estimation techniques, which are not accurate in noisy channels. In this article, we adopt a statistical approach for secure location verification to overcome these limitations. Our proposed method does not rely on any trusted entities and it takes care of the limited precision in distance estimation by using a suitable probability model for the noise. The resulting verification scheme detects and filters out all malicious nodes from the network with a very high probability even when it is in a noisy channel.
ℐ2 RADICAL IN AUTOMATA NEARRINGS
Authors: BOYKETT TIM , WENDT GERHARD
Published: August 2014

Looking at the automata defined over a group alphabet as a nearring, we see that they are a highly complicated structure. As with ring theory, one method to deal with complexity is to look at semisimplicity modulo radical structures. We find some bounds on the Jacobson 2-radical and show that in certain groups, this radical can be explicitly found and the semisimple image determined.
AN ALGORITHMIC FRAMEWORK FOR SOLVING GEOMETRIC COVERING PROBLEMS — WITH APPLICATIONS
Authors: GHASEMI TAHA , GHASEMALIZADEH HOSSEIN , RAZZAZI MOHAMMADREZA
Published: August 2014

In geometric covering problems, the aim is to cover a set of given points using a minimum number of shapes with prescribed properties. These problems extend in many ways such as covering in the presence of obstacles and partial covering. Since in most cases these problems are NP-hard, researchers have developed a large number of approximation algorithms to solve them.

In this paper, with a more general view on these approaches, we propose an algorithmic framework that gives an approximation algorithm for the covering problem at hand, provided that its prerequisites are satisfied. As the result, we present a general class of geometric covering problems for which one can obtain polynomial-time approximation schemes (PTASs). This class of problems involves covering point sets with bounded shapes in a space with fixed dimension. For a problem to be in this class, it must be possible to find a polynomial number of maximal shapes and it must be possible to cover all the points in a small box with a small number of shapes.

Using this framework, we present two new PTASs for the problems of covering with disks in the presence of polygonal obstacles and covering with sectors (pie-shaped wedges). The first problem has never been addressed before and for the second problem, only a logarithmic approximation algorithm was known in general and a 9-approximation algorithm for wide angles.