bluuebunny/crossref_metadata_2025 huggingface dataset:
Establishing Uplift Design Values for Metal Connectors in Light-Frame Construction
Authors: Rosowsky DV , Reed TD , Tyner KG
Published: May 2009

Wind loads cause uplift pressures to be applied to a roof resulting in a net uplift force on the structure. One of the most critical locations in the vertical load path is the connection between the roof and the wall, specifically between the roof rafter (or truss) and the top-plate of the wall. This connection is typically made using mechanical fasteners such as metal straps and nails. The manufacturers of these straps provide allowable capacities for their products based on ASTM test procedures for tension straps, joist hangers, or other similar products. Manufacturers' published design capacities for hurricane straps are based on the lowest value of three test criteria. The first criterion is the ultimate uplift load divided by three, the second is the load 1/8 in. (3.2 mm) deflection, and the third is the allowable design values for nails or other fasteners used to attach the connector to wood members. Recent test results suggest these values may be overly conservative in some cases and that some test criteria or procedures may not be representative of actual design conditions. This paper first reports on a testing program to evaluate uplift capacities of lightframe connections made using commonly available hardware. Based on an evaluation of the results and observations made during the tests, shortcomings of current test procedures and testing program details are described. Deficiencies, and specific needs to overcome them, are identified in the context of structural performance as well as safety.
Measuring the Triaxial Load-Deformation Response of Orthotropic Materials Subjected to Large and Small Strain Regimes
Authors: Saliklis EP , Cramer SM , Hermanson JC
Published: May 2009

A new method for obtaining triaxial stress versus strain data is presented. The method tests cubic specimens and can provide constitutive data along three mutually perpendicular axes. Issues of removing the effects of boundary conditions in the proposed device are discussed. Two devices were constructed and used to obtain triaxial stress versus strain data on paperboard and on redwood samples. Representative data are shown.
Durability of Geosynthetics Based on Accelerated Thermo-Oxidation Testing
Authors: Salman A , Goulias D , Elias V
Published: May 2009

With the increasing use of geosynthetics in civil engineering applications, the geosynthetic industry has developed new and more sophisticated materials. As improved geosynthetics are being introduced, it is necessary to assess their durability with respect to the environmental conditions that they will be exposed to. This requires the development of accelerated tests permitting the degradation prediction of geosynthetics in actual use. To address this need, a basic autooxidation scheme (BAS) has been adapted so as to develop a kinetic model for evaluating their mechanical degradation. Based on the experimental data, the model provides estimates of strength loss with time caused by thermo-oxidation.
A Potential Optical Standard for Resistance Strain Gages
Authors: Sharpe WN
Published: May 2009

The laser-based interferometric strain/displacement gage (ISDG) is an optical technique that measures the change in relative distance between two reflective markers on a specimen surface. When the markers are illuminated with a low-power He-Ne laser, interference patterns are formed in space that can be monitored and related to the relative displacement between them. The ISDG has been used in experiments ranging in duration from 10 μs to 1000 h—a dynamic range of eleven orders of magnitude. This noncontacting technique offers some intriguing possibilities for resistance strain gage calibration. It does not have to be compensated for temperature since there is no thermal expansion of the gage. There are no transverse effects since it measures only the strain along the line between the two markers. It can measure biaxial strains if three markers are placed in an orthogonal pattern. With high-speed detectors, the ISDG can have a very high-frequency response. The fringe motions can be tracked by following the maximums or minimums of the patterns so there is no drift in the electronic instrumentation, which makes the ISDG suitable for calibration of gages used to measure creep strain.

This paper presents a brief overview of the ISDG and discusses application areas where it may be useful in evaluating the performance of resistance strain gages. The two applications where it is most likely to be useful are when elastoplastic strains are measured in regions of high gradients or when the strain is dynamic and elastoplastic.
Additional Comments About a Modified Theodolite Instrument: Conceptual Work
Authors: Obaidat MT , Al-Smadi ZA
Published: May 2009

We previously described a modified surveying theodolite in which the head can be set in a second more elevated position by means of a sliding calibrated extension rod, thus allowing through triangulation the measurement of otherwise inaccessible distances or heights of objects. The recommended sequence of operations required the tilting of the extended rod of the instrument away from the plumb line in order to determine such a distance or height. Unfortunately, this tilting adversely affects the mechanical stability of the instrument. However, it is possible to make triangulation measurements without tilting the rod away from the normal. A new sequence of operations is presented in which the height of a distant object, horizontal distances, and slope distances can be calculated as functions of two measured angles of elevation and the length of the extended rod (along the normal, or plumb line) only. This operational modification has the advantages over the earlier-described procedure of simplicity, lower cost, convenience, greater mechanical stability, and increased precision of measurement.
Measurement and Interpretation of Fatigue Crack Growth in 7075 Aluminum Alloy Using Acoustic Emission Monitoring
Authors: Gong Z , DuQuesnay DL , McBride SL
Published: May 2009

A method for monitoring crack growth during highcycle fatigue tests was demonstrated using acoustic emission (AE) monitoring. Windowing techniques were employed during the recording and interpreting of the AE data. The results provided linear relationships between AE events and amplitudes and crack lengths. The fatigue crack growth results from the AE data were in very good agreement with data measured using an optical microscope.

Fractographic observations of the crack and specimen surfaces showed that secondary cracks formed and linked to the main crack during intermediate stages of crack growth. The crack growth rate calculated from AE data reflected the formation of secondary cracks in this period.
Creep Test of Cured-In-Place Pipe Material Under Tension, Compression, and Bending
Authors: Straughan WT , Tantirungrojchai N , Guice LK , Lin H
Published: May 2009

Inexpensive and easily fabricated long-term creep test devices have been designed and built in order to identify the long-term creep behavior of cured-in-place pipe (CIPP) material under tension, compression, and bending. A special device for testing curved specimens has been designed, built, and evaluated. Loads were applied for 3000 h, and the deformations of CIPP specimens were recorded. Findley's equation, which has been successfully used to predict the creep behavior of plastics for more than 25 years, was used as a baseline for data analysis. The results from Findley's approach were compared with the results from the analyses by theoretical and log-fit methods. The comparison of the three approaches shows that the best estimation of 3000-h creep moduli can be obtained by using the log-fit method.
Effect of Loading Parameters on Post-Overload Fatigue Crack Closure
Authors: Verma BB , Pandey RK , Chinnadurai R
Published: May 2009

The tensile overload cycle has a significant effect on fatigue behavior, resulting in an enhanced crack closure level and reduced fatigue crack growth rate. The present investigation studies the effect of opening mode tensile overload on crack closure in 2024-T3 aluminum alloy and 4130 Cr-Mo steel sheets. It is found that the overload-induced closure parameter KopOLincreases with basic stress intensity range ΔK and overload level. The result further indicates that the significant closure effect can be obtained only beyond a limiting level of overloading ratio (OLR)=1.30 in both the alloys, where OLR is the ratio of the maximum stress-intensity factor in the overloading cycle to the maximum stress-intensity factor in the constant-amplitude loading cycle.
Dynamic Fracture Toughness Measurements on Small Charpy Specimens—A Preliminary Study
Authors: Sharpe WN , Böhme W
Published: May 2009

A technique for measuring dynamic fracture toughness on small specimens is described and preliminary data are presented. Dynamic crack tip opening displacements (CTODs) are measured with laser interferometry over times as short as 10 μs. The measured displacement is converted to stress intensity values via the equations of linear elastic fracture mechanics and the peak value obtained is taken as the dynamic fracture toughness.

Two materials were tested at two different loading rates; a brittle plastic at 103 and 104 MPa-m1/2/s and a ceramic 5 × 104 and 106 MPa-m1/2/s. The results from this new technique were compared with simultaneous results from an instrumented Charpy hammer and, in some cases, from foil gages on the specimens. At the slower rates, the agreement among the results is acceptable. At the higher rates, the instrumented hammer technique is no longer valid. The technique is potentially useful on small, brittle specimens at room and high temperatures.
Controlling, Data Acquisition, and Data Processing for Axial and Shear Creep Tests Using a Computer
Authors: Schmitt FC , Matthews JM
Published: May 2009

The objective of this paper is to provide an inexpensive way of conducting uniaxial creep and shear creep tests, data acquisition, and data processing using a computer. A microcomputer, a math coprocessor, and a graphics laser jet printer were used. A multi-function analog-digital-input-output expansion board increased the computer capacity enabling better precision, data acquisition, and signal analysis. A load cell was used to measure the loads while two linear variable differential transducers (LVDT) were used to monitor the deformations. A signal conditioning unit was used to excite the load cell and LVDTs and to transform the voltage output of the two digital analog channels into electric currents.

Software developed at the University of California, Berkeley was used to conduct the tests. Hard copies of the computer output were obtained showing the relationship between the creep compliance and the time of loading. An example of the application of the creep test results for predicting the permanent deformation of the asphaltic layer of a heavy duty highway is included.
Study of Steel Weldments Using Electronic Speckle Pattern Interferometry
Authors: Sivaganthan J , Ganesan AR , Tan BC , Low KS , Sirohi RS
Published: May 2009

This paper describes the use of Electronic Speckle Pattern Interferometry (ESPI) in the detection of defects in welded steel plates. Experimental results obtained using this technique are described.
Practical Aspects of Dynamic Verification of Extensometers: Part II—Actual Examples
Authors: Albright FJ , Annala J
Published: May 2009

Verification and calibration of an extensometer requires operation at multiple points within the desired operating range. Whereas static calibrations observe changes in sensitivity at different levels within the transducer operating range, dynamic calibrations require duplicating that range of test levels for a range of operating frequencies. Additionally, although the static accuracy of an extensometer is relatively independent of the test machine, dynamic accuracy was believed to be quite dependent.

Test results for dynamic verification of several extensometers are presented. The focus of the tests was to gain an understanding of the advantages and disadvantages of different methods of verification. Testing was generally in accordance with ASTM E 467, Practice for Verification of Constant Amplitude Dynamic Loads in An Axial Load Fatigue Testing Machine. Two excitation methods were used: discrete frequency and pseudo-random. Evaluation of a proposed revision to ASTM E 467 is included. Use of a computer to provide an efficient, high-accuracy method of verifying the calibration of an extensometer was explored. Further testing is recommended to determine if extensometer dynamic verification must be done on the actual test setup, and to what extent it is repeatable.
Measurement Uncertainty Analysis of a Transfer Standard Force Calibration System
Authors: Tovey FM
Published: May 2009

Force transducer calibration may be performed by means of dead weights or by comparison with a transfer standard. Directly applied dead weights with traceability to the National Institute of Standards and Technology (NIST) are primary force standards. Low-capacity force transducers are generally calibrated by primary standards, but for force transducer calibrations above 1000 lb (453.6 kg), many force transducers are calibrated by means of secondary force standards used as transfer standards. The purpose of this paper is to provide a measurement uncertainty analysis of transfer standard force calibration at one test facility. Significant error sources are identified and quantified. The methodology presented is generally applicable; however, the error evaluations are specific to the measurement process and test equipment used.
A New Restraint for High-Load-Transfer Fastener Fatigue Test
Authors: Yigang Z , Xueren W , Yongan Y
Published: May 2009

A test somewhat different from the MIL-STD-1312 test 21 (Shear Joint Fatigue-Constant Amplitude) was explored by using a new type of restraint. Rivet fasteners of two kinds of materials were tested under constant amplitude fatigue loading. The new restraint facilitated the test program and reduced the bending load more efficiently than the current method. Fatigue behavior of aluminum alloy and high-strength steel with single-lap rivet fastener specimens was investigated under different load levels.
Thermal and Mechanical Properties of Cellular Polystyrene and Polyurethane Insulation Materials Aged on a Flat Roof in Hot-Dry Climate
Authors: Ozkan E
Published: May 2009

Cellular polymers, which have been increasingly used for thermal insulation of external walls and roofs since the 1970s, degrade in some cases. The heat transmission of a cellular polymer insulator, the k value, is predominantly dependent on the heat conduction of the air or gas remaining in the cells. An insulator may be aged and start transmitting more energy due to replacement of cell content with different gases or moisture or both, changes in size, softening and creeping under pressure and heat, or penetration of water or mineral particles into cells, or a combination thereof. The solid face also degrades due to ultraviolet light, heat and atmospheric oxygen.

A research project was carried out from January 1988 to December 1991 to investigate the performance of flat roofs, waterproofing, and thermal insulation materials in the hot-dry climatic region of Saudi Arabia. In this context a field station was built and operated for weathering of roofing and insulation materials and for monitoring the surface and the inner temperatures of the applied roof systems.

Basically, two types of cellular polymers, expanded polystyrene and foamed polyurethane, were installed on the roof of the station for insulation. Specimens taken from the fresh, stored, and weathered polystyrene and polyurethane foams were tested to evaluate them according to the selected properties of thermal conductivity, compressive strength at relative deformation, and dimensional stability at elevated temperature. The test results were compared with the requirements presented in the literature and the standard specifications.
Data Analysis Techniques for Impact Tests of Composite Materials
Authors: Svenson AL , Hargrave MW , Bank LC , Ye BS
Published: May 2009

This paper discusses data analysis techniques for instrumented impact tests conducted on glass fiber composite materials. For this study, a drop weight tower has been instrumented with an accelerometer and computer data acquisition system. From the acceleration data obtained, load, energy, velocity, and displacement are calculated in a spreadsheet environment. The resulting data from multiple tests for each material type considered are then averaged producing average plots. The standard deviation is also calculated and plotted for the load data. These curves are then used to characterize the impact behavior of the material. Also introduced is a procedure by which results are normalized by all geometric parameters present in the impact test. This method provides for comparison of test data from three-point bend impact tests having differing geometric parameters.
A Differential Air Deflation Quality Assurance Test for Surgical Gloves
Authors: Carey RF
Published: May 2009

A new quality assurance (QA) test for surgeon's gloves is described which uses a sensitive differential pressure gage to detect glove holes as small as 0.020 mm. The test can be performed quickly and without damage to the glove. Standard holes in nickel masks, ranging in diameter from 0.015 mm to 0.10 mm, were used to calibrate test sensitivity. Air pressure losses in test gloves were compared directly to air pressure in an intact glove. Holes in glove fingers and in glove palms were made with an excimer laser and also with an acupuncture needle. These gloves were then tested with this differential air deflation test and with the standard 1000 mL water fill test. The new test offers similar test sensitivity to the 1000 mL test and, in addition, offers the possibility of quantitative leak testing.
Effects of Sample and Test Variables on Electrical Wire Insulation Flammability
Authors: Rodak EM , Taylor RJ , Hirsch DB , Linley LJ
Published: May 2009

A new test method has been adopted to evaluate the flammability of electrical wire insulation materials. In this test, wire insulation is exposed to an external ignition source while the electrical conductor is internally heated by an electric current. The repeatability of the test and the effects of wire gage and insulation thickness, internal wire temperature, and sample orientation on the wire insulation flammability were evaluated. Experimental results showed that the new test is a practical and repeatable method for evaluating flammability of wire insulation materials.
Effect of Overload Cycles on Thin Steel Roof Claddings during Cyclonic Winds
Authors: Mahendran M
Published: May 2009

During an investigation on thin steel roof claddings under simulated cyclonic wind loading, it was found that trapezoidal roof claddings behaved quite differently to corrugated (arc and tangent type) roof claddings due to the presence of overload cycles. The overload cycles caused a reduction in fatigue life for corrugated roofing whereas the reverse occurred for trapezoidal roofing. This contrasting behavior of the two crest-fixed roof claddings was investigated using small scale roofing models instead of the commonly used large scale two-span roof claddings. It was found that overload cycles formed a weaker locally dimpled mechanism around the fastener holes of corrugated roofing and thus accelerated the fatigue-caused pull-through failure. In contrast, a stronger deformed shape was formed in trapezoidal roofing which delayed the pull-through failure. Both laboratory testing and finite element analysis of small scale models were used to study the contrasting behavior of roof claddings.
Effect of Composition of El-lajjun Oil Shale on Its Calorific Value
Authors: Anabtawi MZ , Nazzal JM
Published: May 2009

A geochemical analysis of El-lajjun oil shale in Jordan was carried out. It was found that El-lajjun oil shale consists of the following groups: organic matter, biogenic calcite and apatite, detrital clay minerals, and quartz. The calorific values of 100 samples of shale were determined. The effect of bore depth, calcium carbonate, organic carbon, and sulfur content on the calorific values were studied. Results were well correlated by the following equation Calorificvalue=352,44(CaCO3)-0.066(S)0.257(Corg)1.141 with correlation coefficient of 0.983 and with an average standard error of 2.63%.
Tuberous Sclerosis Complex Activity Is Required to Control Neuronal Stress Responses in an mTOR-Dependent Manner
Authors: Di Nardo Alessia , Kramvis Ioannis , Cho Namjik , Sadowski Abbey , Meikle Lynsey , Kwiatkowski David J. , Sahin Mustafa
Published: May 2009

Tuberous sclerosis complex (TSC) is a neurogenetic disorder caused by loss-of-function mutations in either theTSC1orTSC2genes and frequently results in prominent CNS manifestations, including epilepsy, mental retardation, and autism spectrum disorder. The TSC1/TSC2 protein complex plays a major role in controlling the Ser/Thr kinase mammalian target of rapamycin (mTOR), which is a master regulator of protein synthesis and cell growth. In this study, we show that endoplasmic reticulum (ER) stress regulates TSC1/TSC2 complex to limit mTOR activity. In addition, Tsc2-deficient rat hippocampal neurons and brain lysates from a Tsc1-deficient mouse model demonstrate both elevated ER and oxidative stress. In Tsc2-deficient neurons, the expression of stress markers such as CHOP and HO-1 is increased, and this increase is completely reversed by the mTOR inhibitor rapamycin bothin vitroandin vivo. Neurons lacking a functional TSC1/TSC2 complex have increased vulnerability to ER stress-induced cell death via the activation of the mitochondrial death pathway. Importantly, knockdown ofCHOPreduces oxidative stress and apoptosis in Tsc2-deficient neurons. These observations indicate that ER stress modulates mTOR activity through the TSC protein complex and that ER stress is elevated in cells lacking this complex. They also suggest that some of the neuronal dysfunction and neurocognitive deficits seen in TSC patients may be attributable to ER and oxidative stress and therefore potentially responsive to agents moderating these pathways.
Rod Phototransduction Determines the Trade-Off of Temporal Integration and Speed of Vision in Dark-Adapted Toads
Authors: Haldin Charlotte , Nymark Soile , Aho Ann-Christine , Koskelainen Ari , Donner Kristian
Published: May 2009

Human vision is ∼10 times less sensitive than toad vision on a cool night. Here, we investigate (1) how far differences in the capacity for temporal integration underlie such differences in sensitivity and (2) whether the response kinetics of the rod photoreceptors can explain temporal integration at the behavioral level. The toad was studied as a model that allows experimentation at different body temperatures. Sensitivity, integration time, and temporal accuracy of vision were measured psychophysically by recording snapping at worm dummies moving at different velocities. Rod photoresponses were studied by ERG recording across the isolated retina. In both types of experiments, the general timescale of vision was varied by using two temperatures, 15 and 25°C. Behavioral integration times were 4.3 s at 15°C and 0.9 s at 25°C, and rod integration times were 4.2–4.3 s at 15°C and 1.0–1.3 s at 25°C. Maximal behavioral sensitivity was fivefold lower at 25°C than at 15°C, which can be accounted for by inability of the “warm” toads to integrate light over longer times than the rods. However, the long integration time at 15°C, allowing high sensitivity, degraded the accuracy of snapping toward quickly moving worms. We conclude that temporal integration explains a considerable part of all variation in absolute visual sensitivity. The strong correlation between rods and behavior suggests that the integration time of dark-adapted vision is set by rod phototransduction at the input to the visual system. This implies that there is an inexorable trade-off between temporal integration and resolution.
Spike Timing, Spike Count, and Temporal Information for the Discrimination of Tactile Stimuli in the Rat Ventrobasal Complex
Authors: Foffani G. , Morales-Botello M. L. , Aguilar J.
Published: May 2009

The aim of this work was to investigate the role of spike timing for the discrimination of tactile stimuli in the thalamic ventrobasal complex of the rat. We applied information-theoretic measures and computational experiments on neurophysiological data to test the ability of single-neuron responses to discriminate stimulus location and stimulus dynamics using either spike count (40 ms bin size) or spike timing (1 ms bin size). Our main finding is not only that spike timing provides additional information over spike count alone, but specifically that the temporal aspects of the code can be more informative than spike count in the rat ventrobasal complex. Virtually all temporal information—i.e., information exclusively related to when the spikes occur—is conveyed by first spikes, arising mostly from latency differences between the responses to different stimuli. Although the imprecision of first spikes (i.e., the jitter) is highly detrimental for the information conveyed by latency differences, jitter differences can contribute to temporal information, but only if latency differences are close to zero. We conclude that temporal information conveyed by spike timing can be higher than spike count information for the discrimination of somatosensory stimuli in the rat ventrobasal complex.
Matrix Metalloproteinase-9 Controls NMDA Receptor Surface Diffusion through Integrin β1 Signaling
Authors: Michaluk Piotr , Mikasova Lenka , Groc Laurent , Frischknecht Renato , Choquet Daniel , Kaczmarek Leszek
Published: May 2009

Matrix metalloproteinase-9 (MMP-9) has emerged as a physiological regulator of NMDA receptor (NMDAR)-dependent synaptic plasticity and memory. The pathways by which MMP-9 affects NMDAR signaling remain, however, elusive. Using single quantum dot tracking, we demonstrate that MMP-9 enzymatic activity increases NR1-NMDAR surface trafficking but has no influence on AMPA receptor mobility. The mechanism of MMP-9 action on NMDAR is not mediated by change in overall extracellular matrix structure nor by direct cleavage of NMDAR subunits, but rather through an integrin β1-dependent pathway. These findings describe a new target pathway for MMP-9 action in key physiological and pathological brain processes.
Homeostatic Synapse-Driven Membrane Plasticity in Nucleus Accumbens Neurons
Authors: Ishikawa Masago , Mu Ping , Moyer Jason T. , Wolf John A. , Quock Raymond M. , Davies Neal M. , Hu Xiu-ti , Schlüter Oliver M. , Dong Yan
Published: May 2009

Stable brain function relies on homeostatic maintenance of the functional output of individual neurons. In general, neurons function by converting synaptic input to output as action potential firing. To determine homeostatic mechanisms that balance this input–output/synapse–membrane interaction, we focused on nucleus accumbens (NAc) neurons and demonstrated a novel form of synapse-to-membrane homeostatic regulation, homeostatic synapse-driven membrane plasticity (hSMP). ThroughhSMP, NAc neurons adjusted their membrane excitability to functionally compensate for basal shifts in excitatory synaptic input. Furthermore,hSMP was triggered by synaptic NMDA receptors (NMDARs) and expressed by the modification of SK-type Ca2+-activated potassium channels. Moreover,hSMP in NAc neurons was abolished in rats during a short- (2 d) or long- (21 d) term withdrawal from repeated intraperitoneal injections of cocaine (15 mg/kg/d, 5 d). These results suggest thathSMP is a novel form of synapse-to-membrane homeostatic plasticity and dysregulation ofhSMP may contribute to cocaine-induced cellular alterations in the NAc.
Entrainment of Slow Oscillations of Auditory Thalamic Neurons by Repetitive Sound Stimuli
Authors: Gao Lixia , Meng Xiankai , Ye Changquan , Zhang Haitian , Liu Chunhua , Dan Yang , Poo Mu-ming , He Jufang , Zhang Xiaohui
Published: May 2009

Slow oscillations at frequencies <1 Hz manifest in many brain regions as discrete transitions between a depolarized up state and a hyperpolarized down state of the neuronal membrane potential. Although up and down states are known to differentially affect sensory-evoked responses, whether and how they are modulated by sensory stimuli are not well understood. In the present study, intracellular recording in anesthetized guinea pigs showed that membrane potentials of nonlemniscal auditory thalamic neurons exhibited spontaneous up/down transitions at random intervals in the range of 2–30 s, which could be entrained to a regular interval by repetitive sound stimuli. After termination of the entraining stimulation (ES), regular up/down transitions persisted for several cycles at the ES interval. Furthermore, the efficacy of weak sound stimuli in triggering the up-to-down transition was potentiated specifically at the ES interval for at least 10 min. Extracellular recordings in the auditory thalamus of unanesthetized guinea pigs also showed entrainment of slow oscillations by rhythmic sound stimuli during slow wave sleep. These results demonstrate a novel form of network plasticity, which could help to retain the information of stimulus interval on the order of seconds.
Low-Conductance HCN1 Ion Channels Augment the Frequency Response of Rod and Cone Photoreceptors
Authors: Barrow Andrew J. , Wu Samuel M.
Published: May 2009

Hyperpolarization-activated cyclic nucleotide-gated (HCN) ion channels are expressed in several tissues throughout the body, including the heart, the CNS, and the retina. HCN channels are found in many neurons in the retina, but their most established role is in generating the hyperpolarization-activated current,Ih, in photoreceptors. This current makes the light response of rod and cone photoreceptors more transient, an effect similar to that of a high-pass filter. A unique property of HCN channels is their small single-channel current, which is below the thermal noise threshold of measuring electronics. We use nonstationary fluctuation analysis (NSFA) in the intact retina to estimate the conductance of single HCN channels, revealing a conductance of ∼650 fS in both rod and cone photoreceptors. We also analyze the properties of HCN channels in salamander rods and cones, from the biophysical to the functional level, showing that HCN1 is the predominant isoform in both cells, and demonstrate how HCN1 channels speed up the light response of both rods and cones under distinct adaptational conditions. We show that in rods and cones, HCN channels increase the natural frequency response of single cells by modifying the photocurrent input, which is limited in its frequency response by the speed of a molecular signaling cascade. In doing so, HCN channels form the first of several systems in the retina that augment the speed of the visual response, allowing an animal to perceive visual stimuli that change more quickly than the underlying photocurrent.
Direct Control of Peripheral Lipid Deposition by CNS GLP-1 Receptor Signaling Is Mediated by the Sympathetic Nervous System and Blunted in Diet-Induced Obesity
Authors: Nogueiras Ruben , Pérez-Tilve Diego , Veyrat-Durebex Christelle , Morgan Donald A. , Varela Luis , Haynes William G. , Patterson James T. , Disse Emmanuel , Pfluger Paul T. , López Miguel , Woods Stephen C. , DiMarchi Richard , Diéguez Carlos , Rahmouni Kamal , Rohner-Jeanrenaud Françoise , Tschöp Matthias H.
Published: May 2009

We investigated a possible role of the central glucagon-like peptide (GLP-1) receptor system as an essential brain circuit regulating adiposity through effects on nutrient partitioning and lipid metabolism independent from feeding behavior. Both lean and diet-induced obesity mice were used for our experiments. GLP-1 (7–36) amide was infused in the brain for 2 or 7 d. The expression of key enzymes involved in lipid metabolism was measured by real-time PCR or Western blot. To test the hypothesis that the sympathetic nervous system may be responsible for informing adipocytes about changes in CNS GLP-1 tone, we have performed direct recording of sympathetic nerve activity combined with experiments in genetically manipulated mice lacking β-adrenergic receptors. Intracerebroventricular infusion of GLP-1 in mice directly and potently decreases lipid storage in white adipose tissue. These effects are independent from nutrient intake. Such CNS control of adipocyte metabolism was found to depend partially on a functional sympathetic nervous system. Furthermore, the effects of CNS GLP-1 on adipocyte metabolism were blunted in diet-induced obese mice. The CNS GLP-1 system decreases fat storage via direct modulation of adipocyte metabolism. This CNS GLP-1 control of adipocyte lipid metabolism appears to be mediated at least in part by the sympathetic nervous system and is independent of parallel changes in food intake and body weight. Importantly, the CNS GLP-1 system loses the capacity to modulate adipocyte metabolism in obese states, suggesting an obesity-induced adipocyte resistance to CNS GLP-1.
The N-Terminal Domain of GluD2 (GluRδ2) Recruits Presynaptic Terminals and Regulates Synaptogenesis in the CerebellumIn Vivo
Authors: Kakegawa Wataru , Miyazaki Taisuke , Kohda Kazuhisa , Matsuda Keiko , Emi Kyoichi , Motohashi Junko , Watanabe Masahiko , Yuzaki Michisuke
Published: May 2009

The δ2 glutamate receptor (GluRδ2; GluD2), which is predominantly expressed on postsynaptic sites at parallel fiber (PF)–Purkinje cell synapses in the cerebellum, plays two crucial roles in the cerebellum: the formation of PF synapses and the regulation of long-term depression (LTD), a form of synaptic plasticity underlying motor learning. Although the induction of LTD and motor learning absolutely require signaling via the cytoplasmic C-terminal domain of GluD2, the mechanisms by which GluD2 regulates PF synaptogenesis have remained unclear. Here, we examined the role of the extracellular N-terminal domain (NTD) of GluD2 on PF synaptogenesis by injecting Sindbis virus carrying wild-type (GluD2wt) or mutant GluD2 into the subarachnoid supracerebellar space ofGluD2-null mice. Remarkably, the expression of GluD2wt, but not of a mutant GluD2 lacking the NTD (GluD2ΔNTD), rapidly induced PF synapse formation and rescued gross motor dyscoordination in adultGluD2-null mice just 1 d after injection. In addition, although the kainate receptor GluR6 (GluK2) did not induce PF synaptogenesis, a chimeric GluK2 that contained the NTD of GluD2 (GluD2NTD–GluK2) did. Similarly, GluD2wtand GluD2NTD–GluK2, but not GluD2ΔNTD, induced synaptogenesis in heterologous cellsin vitro. In contrast, LTD was restored inGluD2-null Purkinje cells expressing a mutant GluD2 lacking the NTD. These results indicate that the NTD of GluD2 is necessary and sufficient for the function of GluD2 in the regulation of PF–Purkinje cell synaptogenesis. Furthermore, our results suggest that GluD2 differently regulates PF synaptogenesis and cerebellar LTD through the extracellular NTD and the cytoplasmic C-terminal end, respectively.
Selective Subcortical Enhancement of Musical Intervals in Musicians
Authors: Lee Kyung Myun , Skoe Erika , Kraus Nina , Ashley Richard
Published: May 2009

By measuring the auditory brainstem response to two musical intervals, the major sixth (E3 and G2) and the minor seventh (E3 and F#2), we found that musicians have a more specialized sensory system for processing behaviorally relevant aspects of sound. Musicians had heightened responses to the harmonics of the upper tone (E), as well as certain combination tones (sum tones) generated by nonlinear processing in the auditory system. In music, the upper note is typically carried by the upper voice, and the enhancement of the upper tone likely reflects musicians' extensive experience attending to the upper voice. Neural phase locking to the temporal periodicity of the amplitude-modulated envelope, which underlies the perception of musical harmony, was also more precise in musicians than nonmusicians. Neural enhancements were strongly correlated with years of musical training, and our findings, therefore, underscore the role that long-term experience with music plays in shaping auditory sensory encoding.
Intramyocellular triglyceride content in man, influence of sex, obesity and glycaemic control
Authors: Haugaard Steen B , Mu Huiling , Vaag Allan , Madsbad Sten
Published: May 2009

Objective

It remains unknown whether sex impacts on intramyocellular triglyceride (IMTG) in obesity, as has been shown in non-obese subjects, and, if so, whether this may have implications on the association between IMTG and insulin sensitivity.

Subject and methods

A muscle biopsy from vastus lateralis was obtained in 27 obese women (body mass index (BMI)=35.5±0.8 kg/m2; mean±s.e.m., percentage of body fat (PBF)=44±1, n=7  impaired fasting glucose, n=7 type 2 diabetes), 20 obese men (BMI=35.8±0.8 kg/m2; PBF=33±1, n=4 impaired-fasting-glucose; n=6 type 2 diabetes) and 12 lean sedentary healthy individuals (controls; n=7 women, BMI=21.8±0.7 kg/m2, PBF=20±2; n=5 men, BMI=23.6±0.5 kg/m2, PBF=13±2). IMTG was determined by chromatography.

Results

IMTG was increased twofold in obese women compared to obese men, lean men and lean women respectively (21.9±2.4 mg/g wet weight, 10.9±1.5, 9.8±2.1 and 10.9±2.4 mg/g, P<0.001). Among obese subjects of either gender IMTG did not increase along with reduced glycaemic control in terms of impaired fasting glucose and diabetes. Plasma insulin levels, which were similar among obese women with different glycaemic control levels, but much lower in lean women, paralleled the changes in IMTG among women. PBF was associated with IMTG in all subjects (P<0.001). In a linear model, sex (P<0.05) and PBF (P<0.05) independently explained variation in IMTG. Plasma free fatty acids (FFA) correlated with IMTG in all subjects (P<0.005).

Conclusion

Obese women display twice as much IMTG as obese men matched for BMI. Increased IMTG could be a pathophysiological element or a mere physiological phenomenon in feminine obesity ensuing prior to impaired glycaemic control, but associated with increased body fat, circulating FFA and insulin.
Novel Methods of Ambulatory Physiologic Monitoring in Patients With Neuromuscular Disease
Authors: Landon Chris
Published: May 2009

This is a summary of the presentation on novel methods of ambulatory physiologic monitoring in patients with neuromuscular disease, presented as part of the program on pulmonary management of pediatric patients with neuromuscular disorders at the 30th annual Carrell-Krusen Neuromuscular Symposium on February 20, 2008.
Complaint stories revisited
Authors: Ferreira Virginia Acuña
Published: May 2009

This article analyses and discusses excerpts from a friendly conversation among three Galician men in relation to broad characterisations of ‘feminine’ and ‘masculine’ interactional styles highlighted by more than two decades of sociolinguistic research on gender and discourse. In line with current tendencies in this area, it is assumed that these characterisations are ‘essentialist’, but it is also maintained that they capture quite well people’s dichotomous conceptions of gendered interactional styles, and that they use to function as an important guide for their behaviour in everyday social life. The main purpose of this article is precisely to illuminate the complex ways in which such conceptions proved as extremely opposing in the analysis of a ‘real’ conversation among men; specifically, the analysis offers empirical evidence that male participants in this speech event are expressing support and connection by collaboratively engaging in the practice of a ‘feminine’ narrative genre like complaint stories (Günthner 1997a), though in an ‘acceptable’ way from the point of view of hegemonic masculinity; this is argued drawing on the fact that the topical focus of the talk is on football issues, and that the tellers do not take a vulnerable role but rather that of a highly indignant victim, as it is manifest in the ways the characters are portrayed and discussed, as well as in the construction of particularly ‘aggressive’ patterns of emotions display.
Language, culture and identity: An ethnolinguistic perspective. Philip Riley (2007)
Authors: Planchenault Gaëlle
Published: May 2009

Language, culture and identity: An ethnolinguistic perspective. Philip Riley (2007) Advances in Sociolinguistics. London: Continuum pp. 265 ISBN 9780826486295
The monolingual framing of international education in Australia
Authors: Liddicoat Anthony J , Crichton Jonathan
Published: May 2009

The concept of international education in Australia is moving from a discourse of attracting students from other countries to one of concern with internationalising curriculum and pedagogy. This internationalisation is motivated by a reconsideration of the appropriateness of curricula to prepare students for the globalised world of work. If one examines universities’ approaches to internationalisation, however, it becomes clear that the dominant ideology of internationalisation is framed from an English-speaking perspective in which English-language monolingualism is constructed as both the basis for and the content of teaching and learning. The monolingual mindset is characterised by: an emphasis on knowledge created in and communicated through English; little attention to the linguistic and cultural context in which knowledge will be used; neglect of the ‘non-English’ competences and capacities of learners and construction of learners’ English as a second language as a deficit and of English language learning as remediation; the ‘invisibility’ of the linguistic and cultural context of English; perceptions that education offered in the first language of students is suspect (easy options, low standards of teaching); and little consideration of knowledge and discipline practices as culturally and linguistically contexted. These characteristics demonstrate that internationalisation is discursively constructed as an English language phenomenon and the valued dimensions of international education are located within the value structures of English which determines the flow of knowledge, learning purposes and practices, academic values and the attribution of value to knowledge as a commodity.
Creating monolingualism in the multilingual courtroom
Authors: Angermeyer Philipp Sebastian
Published: May 2009

This paper contributes to research that has identified an institutional bias towards monolingualism in the legal sphere (Eades 2003, Haviland 2003), investigating how this ‘monolingual worldview’ (Ellis 2006) affects interactions between speakers of minority languages and courtroom professionals in New York City Small Claims Court. Drawing on ethnographic fieldwork and a data-set of 40 recorded arbitration hearings that include speakers of Spanish, Russian, Haitian Creole, and Polish, the paper shows that, while the courtroom itself is multilingual, all individuals besides the interpreters are expected to use one language only, even though most are multilingual to some degree. This ideology is evident in the common practice among legal professionals and interpreters to interrupt and discourage any use of English (i.e. codeswitching) by individuals who are accompanied by an interpreter. On the other hand, court users who avoid the use of English are frequently accused of deceit (‘pretending not to speak English’) by the opposing party. The court’s monolingual bias thus forces bilingual participants to act as monolinguals, thereby creating the appearance of monolingualism as the norm. It is argued that these practices inherently disadvantage minority speakers by preventing them from using the full range of their communicative abilities, and by making language choice a factor in the assessment of their credibility.
Futuros Docentes y Futuros Investigadores se Expresan sobre el Modelado en Física
Authors: Islas Stella Maris , Pesa Marta A.
Published: May 2009

Se presenta una investigación exploratoria sobre las concepciones de modelo científico sustentadas por estudiantes universitarios de Licenciatura en Física y de Profesorado en Física. A partir de entrevistas individuales semi-estructuradas se indagaron algunas ideas clave acerca del modelado y del empleo de modelos. Los resultados muestran a los futuros licenciados con una postura frente al tema que es acorde con las consensuadas en las epistemologías actuales, y se registran evidencias de su experiencia en el manejo de modelos. Ello no ocurre con los futuros docentes, quienes presentan ms acentuadamente las dificultades que, sobre este tema, se han detectado en otras investigaciones con estudiantes.
Determinação dos Coeficientes de Atrito Estático e Cinético Utilizando-se a Aquisição Automática de Dados
Authors: Mossmann Véra Lúcia da Fonseca , Catelli Kelen Berra de Mello Francisco , Libardi Helena , Damo Igino Santo
Published: May 2009

Este trabalho descreve a informatização de um experimento tradicional envolvendo a medida de coeficientes de atrito. A montagem experimental aqui sugerida é destinada ao ensino de física a nível médio. Nela, as forças de atrito cinético e estático, para um par de superfícies, são obtidas em tempo real quando um corpo é levado do repouso ao movimento. A relação entre a força de atrito e a força normal também é apresentada. Os dados são adquiridos por um sensor de força e um sensor de posição acoplados a uma interface conectada a um computador. Os gráficos da força de atrito em função do tempo são obtidos em tempo real.
Visualizando os Modos Normais de Vibração com o Computador
Authors: Jácome S. S. B. , Medeiros F. F. de , Corso G. , Lucena L. S.
Published: May 2009

Neste trabalho desenvolvemos um programa educativo versando sobre modos normais em uma cadeia de osciladores acoplados. O usuário do programa pode simular a evolução dinâmica de uma cadeia de osciladores escolhendo condições iniciais tanto em coordenadas cartesianas como em coordenadas normais. Focalizamos o efeito do desacoplamento do sistema de equações diferenciais (passagem de coordenadas cartesianas para coordenadas normais) sobre as trajetórias dos osciladores do ponto de vista da dinâmica qualitativa. Através das características da evolução dinâmica, quase-periodicidade ou periodicidade, o estudante ganha intuição sobre o significado das formas normais.
Constantes de Movimento para um Potencial Dependente da Velocidade
Authors: Castro A. S. de , Marchesetti E. L. , Feldt A.
Published: May 2009

Simetrias geométricas contínuas para um sistema fechado de partículas são investigadas. Por suposto, as interações são deriváveis de uma função potencial dependente das velocidades das partículas. Tanto os vínculos sobre a forma da função potencial quanto os princípios de conservação resultantes das simetrias espaço-temporais contínuas são derivados. A lagrangiana de Darwin é utilizada como ilustração para o caso do movimento lento de cargas elétricas na formulação deMaxwell-Lorentz da eletrodinâmica clássica. O momento linear, o momento angular e a energia, quantidades dependentes de calibre, são obtidos.
Capacitor Cilíndrico Excêntrico
Authors: Carvalho Ricardo Egydio de , Silva Ana Paula Morinelli Amaral da
Published: May 2009

Consideramos o capacitor cilíndrico com a placa interna fora de centro e calculamos a capacitância correspondente usando a técnica da transformação conforme. Observamos que a capacitância pode ser ampliada e a quantidade de material para construir o capacitor pode ser reduzida com a geometria excêntrica.Este resultado pode ser usado como tutorial de uma aula experimental para medir o efeito da excentricidade na capacitância e na construção do capacitor cilíndrico.
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Authors: Solano F. , Gil J. , Pérez A.L. , Suero M.I.
Published: May 2009

En este trabajo pretendemos comprobar que las preconcepciones que los alumnos poseen sobre los circuitos eléctricos de corriente continua son comunes a alumnos de diferentes edades y están tan fuertemente arraigadas que ni la instrucción durante muchos años permite modificarlas.