bluuebunny/crossref_metadata_2025 huggingface dataset:
Does lying on the right side increase the rate of gastric emptying?
Authors: Burn‐Murdoch R , Fisher M A , Hunt J N
Published: December 2015

1. Saline test meals (750 ml., 125 mM‐NaCl) were given by tube into the stomachs of five subjects who were either sitting, lying on the left side, or lying on the right side. The gastric contents were recovered at 10 min. The rate of gastric emptying was assessed from the recovery of the original solution, marked with phenol red. 2. The mean volume of this rapidly emptying test solution recovered after 10 min was 215 ml. from subjects lying on the right side and 431 ml. from subjects lying on the left side (P < 0.005) and 308 ml. from the sitting subjects. 3. Similar studies were made with 750 ml. test meals of a solution of glucose monohydrate (100 g/l.) given to the same subjects in the same positions, but the recoveries of this more slowly emptying solution were made at 20 min. 4. There was no statistically significant difference between the volumes recovered when subjects lay on their left sides (589 ml), when they lay on their right sides (555 ml.), and when they were sitting (564 ml.). 5. These results are consistent with posture influencing gastric emptying provided the given meal does not strongly activate duodenal receptors mediating the slowing of gastric emptying.
Restoration of focal multiple innervation in rat muscles by transmission block during a critical stage of development
Authors: Brown M. C. , Holland R. L. , Hopkins W. G.
Published: December 2015

1. The soleus, extensor digitorum longus and peroneus tertius muscles of the hind leg were paralysed by botulinum toxin injection in neonatal rats varying in age from 8 to 31 days. The soleus muscle was similarly paralysed in adult rats.

2. Muscles were excised after different periods of block, neuromuscular transmission was assessed in vitro, and the nerve terminal size and amount of terminal sprouting and multiple innervation determined histologically using silver (Ag) and zinc iodide‐osmium (ZIO) tetroxide stains.

3. Recovery from the block induced by botulinum toxin was more rapid in immature multiply‐innervated muscles than in muscles of older rats in which all multiple innervation had been eliminated.

4. Terminals in muscles blocked during the first month after birth grew rapidly in size and developed a characteristic granulose morphology in the first few days following the block. This change did not occur in fully adult rat solei.

5. Sprouts growing from the terminals were infrequent in muscles paralysed before day 16. Terminal sprouts were more frequent in muscles paralysed between 16 and 31 days of age, but were very infrequent in adult solei.

6. In confirmation of Thompson, Kuffler & Jansen (1979) paralysis begun at 10 days was followed initially by a continued fall in multiple innervation detected electrophysiologically. After 2 days the percentage of muscle fibres with more than one input rose. The extra inputs did not come from terminal sprouts. They innervated the single synaptic site on each muscle fibre as they do during normal synaptogenesis.

7. The amount of multiple innervation regained 5‐10 days after the start of paralysis became progressively less the later paralysis started and was approximately equal to the level existing at the time the block was begun. Thus paralysis starting on or after day 16 (when all excess inputs have normally withdrawn) caused no return of multiple innervation.

8. The return of multiple inputs and the swelling of the nerve terminals are presumably responses of the motoneurone to growth stimuli from inactive muscle. It is not clear whether the return of multiple innervation in the 10‐15 day old rats is due to reactivation of inputs still in close contact with the end‐plate before withdrawal or to regrowth of partly retracted nerve branches.

9. A parallel is drawn between the limited period when inactivity can reinstate multiple innervation, and the critical period in the developing visual cortex.
The effect of exercise on the central‐chemoreceptor threshold in man.
Authors: Casey K , Duffin J , McAvoy G V
Published: December 2015

1. The threshold of the central chemoreceptors was determined under resting and three exercise conditions in four volunteers. 2. The method used was the hyperoxic, Read rebreathing technique with prior hyperventilation. Plots of resting ventilation vs. carbon dioxide consisted of two straight‐line segments of different slopes above and below a breakpoint which was taken as the central‐chemoreceptor threshold at rest. 3. The threshold during exercise was determined from plots of exercise ventilation vs. carbon dioxide in a similar way, but the points for these plots were obtained in a different manner. They were obtained from a number of separate rebreathing experiments, so as to avoid the divergence between mouth and central‐chemoreceptor carbon dioxide levels during rebreathing in exercise. 4. Exercise was started abruptly during rebreathing experiments similar to those at rest, at a particular level of carbon dioxide, and exercise ventilation was measured at the third breath. Each rebreathing experiment therefore provides one point for the exercise ventilation vs. carbon dioxide plot. 5. The results showed that the central‐chemoreceptor threshold during exercise was not different from the resting threshold, and that the initial, fast component of exercise ventilation was independent of the chemical drive to breathe.
Effect of channel blockers on potassium efflux from metabolically exhausted frog skeletal muscle.
Authors: Castle N A , Haylett D G
Published: December 2015

1. 86Rb and 42K have been used to assess potassium exchange in frog skeletal muscle which had been metabolically exhausted by electrical stimulation (1 Hz) after treatment with 2 mM‐cyanide and 1 mM‐iodoacetate. These conditions led to the development of rigor. 2. Poisoning by itself induced a small but variable increase in tracer efflux. Complete mechanical exhaustion subsequent to electrical stimulation was, however, accompanied by a 5‐6 fold increase in the rate coefficient for both 86Rb and 42K efflux. In the case of rubidium this was maintained for at least 20 min and often for up to 1 h. 3. The increase in tracer efflux induced by metabolic exhaustion was inhibited by barium (0.03‐5 mM) in a reversible and concentration‐dependent manner. Inhibition was also observed with glibenclamide (3‐100 microM), tolbutamide (0.3‐2 mM), TEA (5‐100 mM) and the local anaesthetics lignocaine (1‐3 mM) and tetracaine (1 mM). Quinine produced a dual response consisting of an inhibitory component which was most clearly seen at low concentrations (0.3 mM) and an enhancement of tracer efflux that became increasingly dominant at higher concentrations (1‐10 mM). 4. Both apamin (30 and 100 nM) and Israeli scorpion (Leiurus quinquestriatus) venom (16 micrograms ml‐1) produced little or no block of the tracer efflux activated by metabolic exhaustion. Similarly 4‐aminopyridine (3 mM) and decamethonium (0.3 mM) were without obvious effect. 5. It is concluded that metabolic exhaustion of frog skeletal muscle leads to an increased permeability to both 42K and 86Rb. Our results with channel blockers suggest that this K+ permeability can be attributed neither to the delayed rectifier nor to an apamin‐ or charybdotoxin‐sensitive calcium‐activated K+ permeability (PK(Ca) but may be predominantly due to activation of ATP‐sensitive channels similar to those found in the beta‐cells of pancreatic islets.
Characterization of two types of calcium channels in mouse neuroblastoma cells.
Authors: Narahashi T , Tsunoo A , Yoshii M
Published: December 2015

1. Two types of voltage‐sensitive calcium channels were identified and studied in the neuroblastoma cell line N1E‐115. Calcium channel currents as carried by Ba2+ (50 mM) were recorded using the whole‐cell variation of the patch‐electrode voltage‐clamp technique. 2. A transient (type I) inward Ba2+ current was evoked by a step depolarization from a holding potential of ‐80 mV to potentials more positive than ‐50 mV. The current amplitude became maximum around ‐20 mV. 3. A depolarization to potentials more positive than ‐20 mV evoked a long‐lasting (type II) component of the inward Ba2+ current. This component reached its maximum around +10 mV and did not inactivate during a prolonged depolarizing pulse lasting 400 ms. 4. When preceded by a 5 s conditioning pulse to ‐30 mV, step depolarization failed to evoke a transient current due to inactivation. However, it induced a long‐lasting current. 5. A transient current isolated as the component sensitive to conditioning depolarization became faster in its time course and smaller in its amplitude with membrane depolarization. The current direction was still inward at +60 mV. 6. From the differential voltage sensitivity and the independent channel activity described above, calcium channels responsible for the transient current (type I channel) and those responsible for the long‐lasting current (type II channel) were considered to be two different entities. 7. Cd2+ preferentially blocked type II channels, whereas La3+ was a highly potent blocker for both types of calcium channels. 8. The relative potency for block by polyvalent cations was as follows (apparent dissociation constant in microM): La3+, 1.5 much greater than Ni2+, 47 greater than Cd2+, 160 = Co2+, 160 for type I channels, and La3+, 0.9 greater than Cd2+, 7.0 much greater than Ni2+, 280 greater than Co2+, 560 for type II channels. 9. The two types of calcium channels were equally sensitive to the temperature. The current amplitude was reduced by cooling below 30 degrees C. The temperature coefficient (Q10) value was estimated to be 3.0 between 20 and 30 degrees C, and 15.0 below 20 degrees C. Above 30 degrees C, warming reduced the amplitude slightly. 10. External application of dibutyryl adenosine 3',5'‐phosphate (dibutyryl cyclic AMP) (1 mM) caused an increase in the amplitude of the type II current by 30‐50%, while failing to enhance the type I component.(ABSTRACT TRUNCATED AT 400 WORDS)
Calcium buffering in axons and axoplasm of Loligo.
Authors: Baker P F , Umbach J A
Published: December 2015

1. Ca‐selective micro‐electrodes were used to measure free Ca concentration in axons and extruded axoplasm. 2. Free Ca in axons immersed in artificial sea water containing 3 mM‐Ca averaged 77 nM in freshly dissected axons and 4.9 microM in cyanide‐ or azide‐poisoned axons. 3. Extruded axoplasm maintained a free Ca only a little higher than that of the axons from which it was obtained. 4. Axoplasmic buffering was investigated by titrating isolated axoplasm with CaCl2 or K‐EGTA and monitoring the change in free Ca. Energy‐dependent and energy‐independent components of Ca binding could be recognized in fresh axoplasm. The energy‐dependent fraction could be further subdivided into Ruthenium Red‐sensitive and Ruthenium Red‐insensitive components and the energy‐independent fraction into a component of high affinity and rather low capacity and another component of low affinity and large capacity. 5. The Ruthenium Red‐sensitive process could accumulate many millimoles Ca per kilogram axoplasm while still maintaining a free Ca close to 100 nM. After injection of Ruthenium Red into fresh axoplasm, binding is dramatically altered so that it closely resembles that in a metabolically poisoned preparation. 6. The Ruthenium Red‐insensitive process has a small capacity and appears to be capable of lowering free Ca to about 200 nM. It can, however, lower free Ca to 50‐150 nM if oxalate is also present. 7. Simultaneous measurement of pH and free Ca showed that axoplasmic pH only begins to fall appreciably in response to added Ca when mitochondrial Ca buffering becomes impaired. 8. Raising axoplasmic levels of Na or Li, but not K, tends to bring about a concomitant rise in free Ca.
Changes in the length of the human biceps brachii muscle during elbow movements.
Authors: Fellows S J , Rack P M
Published: December 2015

1. Needles inserted into the biceps move with the muscle as the elbow flexes or extends. Pairs of needles were used to indicate changes in length of the muscle fibres. 2. During low‐frequency flexion‐extension movements the biceps lengthened as the joint extended. 3. When, however, joint movements at greater than 2.2 Hz were maintained by external electrical stimulation of triceps and the long head of biceps, or of biceps alone, the biceps lengthened and shortened in antiphase to the joint movement. The elastic properties of the biceps tendons then combined with the mass of the forearm as a spring‐mass system whose natural frequency was about 2.2 Hz. 4. No such phase reversal appeared during voluntary elbow movements at frequencies up to 5 Hz. It was concluded that the combined tendons of biceps, brachialis and brachioradialis made a much less compliant muscle‐to‐bone coupling. 5. The results are discussed in relation to possible tremor mechanisms.
The effects of hypertonicity on tension and intracellular calcium concentration in ferret ventricular muscle.
Authors: Allen D G , Smith G L
Published: December 2015

1. Tension and intracellular calcium concentration ([Ca2+]i) were measured in isolated ferret papillary muscles exposed to hypertonic solutions. [Ca2+]i was measured with aequorin which was microinjected into surface cells of the preparation. Correction was made for the effects of ionic strength on aequorin sensitivity to Ca2+. 2. Application of 100 mM‐mannitol increased both developed tension and the intracellular Ca2+ signals on contraction (the Ca2+ transients). 300 mM‐mannitol increased the Ca2+ transients further but led to a decrease in developed tension. 3. Mannitol caused a concentration‐dependent slowing in the time course of a stimulated contraction but had no effect on that of the Ca2+ transient. 4. As the mannitol concentration was increased, the muscles exhibited increased viscosity which was demonstrated by measuring the tension response to a sudden stretch during diastole. This is probably a consequence of cell shrinkage and may cause the slower time course of the contraction. 5. In the presence of 300 mM‐mannitol, oscillations of diastolic [Ca2+]i were detectable in both stimulated and quiescent preparations. However, in stimulated preparations the oscillations in mannitol were smaller than when a Ca2+ transient of similar amplitude was achieved by other means. 6. Immediately after the application or removal of mannitol large spontaneous Ca2+ signals were often observed. These signals were even larger in Na+‐free solutions, suggesting that they cannot be attributed to Na+‐Ca2+ exchange. 7. The increase in developed tension in 100 mM‐mannitol can be accounted for by the increased Ca2+ transients in combination with the inhibitory effects of ionic strength on myofibrillar tension production (Kentish, 1984). The decrease in developed tension at 300 mM‐mannitol is dominated by the inhibitory effect of increased ionic strength on maximum Ca2+‐activated tension.
Inward rectification in freshly isolated single smooth muscle cells of the rabbit jejunum.
Authors: Benham C D , Bolton T B , Denbigh J S , Lang R J
Published: December 2015

1. Single smooth muscle cells were obtained by collagenase digestion of longitudinal muscle of rabbit jejunum. Membrane potential or current under voltage clamp was recorded by patch‐clamp technique in the whole‐cell recording mode at 22‐25 degrees C. 2. At a membrane potential of ‐50 mV small hyperpolarizing current pulses produced electrotonic potentials which asymptotically approached a steady‐state size and did not 'sag'. Stronger hyperpolarization resulted in a 'sag' of the electrotonic potential. Under voltage clamp an inward current, i, was activated in the range ‐60 to ‐110 mV. 3. This current had an equilibrium potential of ‐24.5 +/‐ 3.5 mV which was shifted negatively by reducing the sodium concentration, and positively by raising the potassium concentration of the bathing solution. 4. This current was blocked by caesium (1 mM) but less affected by barium ions up to 10 mM. 5. The time course of i upon stepping into its activation range was accelerated by increasing negativity and following an initial short delay could be described by a single exponential with a time constant in the range 60 s(‐60 mV) to 1 s(‐130 mV). 6. It is concluded that these jejunal cells possess a current to which sodium and potassium ions make a contribution which is responsible for the inward rectification they show upon hyperpolarization. This current is activated in a range which would allow it to contribute to the slow potential changes shown by longitudinal jejunal muscle.
Comparison of rates of cation release and of conformational change in dog kidney Na, K‐ATPase.
Authors: Glynn I M , Hara Y , Richards D E , Steinberg M
Published: December 2015

1. It is now widely believed that the main rate‐limiting step in the sodium‐potassium pump (Na, K‐ATPase) cycle is a conformational change between two forms of the dephosphoenzyme (E2 and E1) and that this change releases to the cell interior potassium ions occluded within the E2 form. 2. If this hypothesis is correct, and if occluded ions cannot be released directly from dephosphoenzyme in the E2 conformation, we should expect that, under any given conditions, the rate of release of the occluded ions would be identical with the rate of the conformational change. 3. Using the potassium congeners 86Rb, 137Cs and 204Tl, the rates of release of the occluded ions can be measured by a rapid ion‐exchange technique. Using the fluorescence probes fluorescein isothiocyanate (FITC), eosin or 5‐iodoacetamido‐fluorescein (5‐IAF), the rates of the conformational change can be measured by stopped‐flow fluorimetry. 4. A comparison of the two rates in the absence of ATP showed that the rate of release of the occluded ions was usually somewhat faster than the rate of the fluorescence change. The discrepancy was probably caused by a very slow direct release of occluded ions from enzyme in the E2 form, but we cannot exclude the possibility that it is the result of systematic errors. In the presence of 5 microM‐ATP, both rates were increased and there was no significant difference between them. 5. The results are compatible with the hypothesis that the same conformational change alters the fluorescence of the fluorescent probes and releases the occluded potassium congener ions.
Position sense at the proximal interphalangeal joint of the human index finger.
Authors: Ferrell W R , Smith A
Published: December 2015

1. The ability of eleven normal subjects to match the position of the proximal interphalangeal joints was tested. The right index finger (target finger) was moved to a given position and the subject was required to match this with the left index finger (matching finger). 2. Digital nerve block of the matching finger resulted in substantial impairment in matching performance in seven out of eight subjects. 3. Anaesthesia of the target finger in two subjects also produced obvious position matching deficit, in a pattern consistent with subjective sensation of target finger position. 4. The effects of digital nerve block were specific, as neither injection of saline into the matching finger, nor anaesthesia of adjacent fingers, impaired performance. 5. In one subject, injection of local anaesthetic into the synovial cavity of the matching finger also resulted in impairment of matching performance, indicating that articular receptors contribute to position sense at this joint. 6. Passive displacement of the matching finger did not produce significantly greater errors than those occurring with active finger positioning either under control conditions or during digital nerve block of the matching finger. 7. Although digital nerve block produced substantial impairment of matching performance, there was not complete loss of proprioceptive sensation, suggesting that muscle receptors also contribute. This was confirmed in experiments where isotonic loading of the matching finger while it was anaesthetized resulted in significant alteration in matching performance compared to anaesthesia alone. 8. It is concluded that no one source of afferent input can be excluded from contributing to proprioception at the index finger. It is likely that under different operating conditions several afferent sources are required to provide optimal proprioceptive resolution.
Quisqualate‐ and kainate‐activated channels in mouse central neurones in culture.
Authors: Ascher P , Nowak L
Published: December 2015

1. Quisqualate‐ and kainate‐induced currents were recorded in mouse central neurones in culture, using both 'whole‐cell' and 'outside‐out' configurations. Experiments were made at room temperature. 2. Both quisqualate‐ and kainate‐induced currents invert at 0 mV when the extracellular and intracellular solutions contain similar concentrations of monovalent cations. The changes of reversal potential produced by changes in the monovalent cation concentrations are consistent with the hypothesis that both agonists activate channels selectively permeable to cations. 3. The spectral analysis of the quisqualate‐ and kainate‐induced currents recorded in the whole‐cell mode indicates that the main component of the quisqualate noise has a time constant of 10‐15 ms while the main component of the kainate noise has a time constant of 2‐3 ms. 4. In outside‐out patches most of the quisqualate‐induced current was carried by channels with a conductance of about 8 pS. A small fraction of the quisqualate‐induced current appears to be carried by two other channels: the 'NMDA channel' (40‐50 pS) (Ascher, Bregestovski & Nowak, 1988) and a 'fast' channel, with a conductance of 15‐35 pS, which was not activated by low concentrations of L‐glutamate or by NMDA (N‐methyl‐D‐aspartate). 5. Most of the kainate‐induced current can be attributed to a channel characterized by a conductance of about 4 pS. Here again, outside‐out patches revealed the presence of an additional channel, with a conductance of about 20 pS. 6. The results are consistent with the notion that there are at least three distinct receptors for excitatory amino acids, each preferentially activated by either NMDA, quisqualate or kainate, each opening channels with multiple conductance states. Other possibilities are discussed.
Effects of raised extracellular potassium on the excitability of, and hormone release from, the isolated rat neurohypophysis.
Authors: Leng G , Shibuki K , Way S A
Published: December 2015

1. Single neurohypophyses from male rats were maintained in an in vitro perifusion chamber. Ion‐sensitive microelectrodes were introduced into the tissue to measure changes in [K+]o and [Ca2+]o during electrical stimulation. 2. Electrical stimulation at 6 Hz for 1 min and 30 Hz for 12 s raised [K+]o by 5.4 +/‐ 0.4 and 13.5 +/‐ 0.5 mM (mean +/‐ S.E.M., n = 8) respectively. To investigate the effects of raised [K+]o on the excitability of the neurosecretory terminals, stimulations were repeated in media of altered K+ concentration. The increase in [K+]o evoked by 6 Hz stimulation was elevated in 10 mM‐K+ medium (133% of that in 5 mM‐K+ medium) and reduced in 0 mM‐K+ medium and in 25 mM‐K+ medium. Thus it appeared that stimulus‐induced changes in [K+]o might enhance the excitability of the tissue during electrical activation. 3. To test this hypothesis, we measured the field potential responses evoked by 0.5 Hz stimulation in media of different K+ concentrations. The size of the field potential was enhanced in 10 mM‐K+ medium and depressed in 0 mM‐K+ medium and in 25 mM‐K+ medium. 4. Electrical stimulation (6 Hz, 1 min) decreased [Ca2+]o by 10.9 +/‐ 1.8% (n = 6). This decrease was absent in the presence of 1 microM‐tetrodotoxin or 1 mM‐cadmium. Again, the [Ca2+] response to stimulation was enhanced in 10 mM‐K+ medium and depressed in 0 mM‐K+ medium or 25 mM‐K+ medium. 5. The release of vasopressin and oxytocin evoked by stimulation at 6 or 30 Hz from isolated neurohypophyses was measured by radioimmunoassay in a separate series of experiments. Stimulation at 30 Hz for 1 min released 5‐ to 6‐fold more hormone than stimulation at 6 Hz for 5 min. Release evoked by 6 Hz stimulation was enhanced in 15 mM‐K+ medium and depressed in 25 mM‐K+ medium. 6. We conclude that the rise in [K+]o that accompanies high‐frequency activation of axons and terminals in the neurohypophysis contributes to the facilitation of hormone release with increasing frequencies of stimulation, and in particular to the efficiency of the milk‐ejection burst discharge of oxytocin neurones for evoking oxytocin release.
Effects of High Frequency Droplet Train Impingement on Crown Propagation Dynamics and Heat Transfer
Authors: Muthusamy J. P. , Zhang Taolue , Alvarado Jorge , Kanjirakat Anoop , Sadr Reza
Published: December 2015

The objective of this study is to investigate the hydrodynamics and heat transfer phenomena due to high frequency droplet train impingement on a pre-wetted solid surface for electronic cooling applications. The effects of crown propagation dynamics and surface heat transfer were investigated experimentally and numerically. Experimentally, a single stream of mono-dispersed HFE-7100 droplets was generated using a piezo-electric droplet generator at a frequency ( f ) of 6000 Hz with a droplet Weber number (We) of 280. Droplet-induced crater and crown were imaged using a high speed camera system. Numerically, the ANSYS Fluent CFD tool was used to simulate the droplet train impingement process. A reasonable agreement was reached between experimental and numerical data in terms of crown propagation dynamics. Numerical simulations reveal that at the instant of initial spot formation, the magnitude of droplet velocity is almost identical to the crown's radial velocity. The instantaneous temperature field obtained by numerical simulations shows that heat transfer was most effective within the crown propagation region due to the radial momentum generated by the droplets, which leads to a large velocity gradient within the liquid film. A significant increase in surface temperature was observed beyond a radial position of 500 μm. In summary, high frequency droplet impingement leads to a very small temperature gradient in the radial direction within the droplet-induced impact crater. This study will benefit in understanding the relationship between the droplet parameters and surface heat transfer for different cooling applications involving impinging droplets.
Mapping Thickness Dependent Thermal Conductivity of GaN
Authors: Ziade Elbara , Yang Jia , Brummer Gordie , Nothern Denis , Moustaks Theodore , Schmidt Aaron
Published: December 2015

Frequency domain thermoreflectance (FDTR) is used to create quantitative maps of thermal conductivity and thickness for a thinning gallium nitride (GaN) film on silicon carbide (SiC). GaN was grown by molecular beam epitaxy on a 4H-SiC substrate with a gradient in the film thickness found near the edge of the chip. The sample was then coated with a 5 nm nickel adhesion layer and a 85 nm gold transducer layer for the FDTR measurement. A piezo stage raster scans the sample to create phase images at different frequencies. For each pixel, a periodically modulated continuous-wave laser (the red pump beam) is focused to a Gaussian spot, less than 2 um in diameter, to locally heat the sample, while a second beam (the green probe beam) monitors the surface temperature through a proportional change in the reflectivity of gold. The pump beam is modulated simultaneously at six frequencies and the thermal conductivity and thickness of the GaN film are extracted by minimizing the error between the measured probe phase lag at each frequency and an analytical solution to the heat diffusion equation in a multilayer stack of materials. A scanning electron microscope image verifies the thinning GaN. We mark the imaged area with a red box. A schematic of the GaN sample in our measurement system is shown in the top right corner, along with the two fitting properties highlighted with a red box. We show the six phase images and the two obtained property maps: thickness and thermal conductivity of the GaN. Our results indicate a thickness dependent thermal conductivity of GaN, which has implications of thermal management in GaN-based high electron mobility transistors.
Optical Analysis of a Two Stage XX Simultaneous Multiple Surface Concentrator for Parametric Trough Primary and Flat Absorber With Application in Direct Steam Generation Solar Thermal Plants
Authors: Núnez Bootello Juan Pablo , Price Henry , Pérez Manuel Silva , Castellano Manuel Doblaré
Published: December 2015

Today most commercial parabolic trough collector (PTC) solar power plants make use of the well-known LS3/Eurotrough optics. The PTC has a concentration ratio relative to the maximum thermodynamic limit equal to 0.31. In order to improve the competiveness of PTC technology, two well differentiated R&D strategies have been undertaken: (i) developing larger parabolic troughs, which places a higher demand in tracking accuracy and lower tolerances with respect to wind loads, quality of mirrors, control and assembly imprecisions, and (ii) developing secondary concentrators with the aim of bringing the concentration ratio relative to the maximum one as close to 1 as possible. In this paper, a parametric trough collector (PmTC) for a flat receiver designed with the simultaneous multiple surface (SMS) method is proposed. The method assumes zero transmission, absorption, and reflection optical losses and allows for both reflective primary and secondary surfaces (XX-reflective plus reflective) to be simultaneously designed, guaranteeing Etendue matching. The proposed PmTC geometry increases the referred ratio up to 0.59 with a rim angle greater than 100 deg and with the same effective acceptance angle as the PTC. The flat absorber can be replaced with a multitube receiver for application in direct steam generation (DSG).
Dynamic Modeling and Spectrum Analysis of Macro–Macro Dual Driven System
Authors: Yu Hanwen , Feng Xianying
Published: December 2015

This paper designs a preload adjustable rotary nut ball screw dual-driven micro feed system, due to the elastic property of the feed system has great influence on its own frequency–response characteristics, which can be identified by analyzing the amplitude relationship between the torque input signal and the acceleration output signal. In order to get the structural dynamic of the dual-driven servomechanism, which is first modeled through lumped mass method, the frequency–response characteristics are calculated using the Lagrange equation and the state-space method. Finally, the frequency–response characteristics of a macro–macro dual-driven and single-driven systems are compared via numerical analysis, and the influence of changes in the preload, torsional rigidity, and table's total mass on the frequency–response characteristics are studied.
Analytical and Numerical Validation of a Moving Modes Method for Traveling Interaction on Long Structures
Authors: Recuero Antonio M. , Escalona José L.
Published: December 2015

This work is devoted to the validation of a computational dynamics approach previously developed by the authors for the simulation of moving loads interacting with flexible bodies through arbitrary contact modeling. The method has been applied to the modeling and simulation of the coupled dynamics of railroad vehicles moving on deformable tracks with arbitrary undeformed geometry. The procedure presented makes use of a fully arbitrary Lagrangian–Eulerian (ALE) description of the long flexible solid (track) whose mechanical properties may be captured using a dynamics-preserving selection of modes, e.g., via a Padé approximation of a transfer function. The modes accompany the contact interaction rather than being referred to a fixed frame, as it occurs in the finite-element floating frame of reference formulation. In the method discussed in this paper, the mesh, which moves through the long flexible solid, is defined in the trajectory coordinate system (TCS) used to describe the dynamics of the set of bodies (vehicle) that interact with the long flexible structure. For this reason, the selection of modes can be focused on the preservation of the dynamics of the structure instead of having to ensure the structure's static displacement convergence due to the motion of the load. In this paper, the validation of the so-called trajectory coordinate system/moving modes (TCS/MM) method is performed in four different aspects: (a) the analytical mechanics approach is used to obtain the equations of motion in a nonmaterial volume, (b) the resulting equations of motion are compared to the classical discretization procedures of partial differential equations (PDE), (c) the suitability of the moving modes (MM) to describe deformation due to variable-velocity moving loads, and (d) the capability of the finite nonmaterial volume to describe the dynamics of an infinitely long flexible body. Validation (a) is completely general. However, the particular example of a moving load applied to a straight beam resting on a Winkler foundation, with known semi-analytical solution, is used to perform validations (b), (c), and (d).
Concentration of microparticles and bubbles in standing waves
Authors: Ostrovsky Lev
Published: December 2015

This paper studies the collective dynamics of microparticles in plane and cylindrical resonators. Based on the known results regarding the motion of a single particle under the action of acoustic radiation force, concentration and separation of particles in standing waves are investigated. As an example, spherical particles (cells) with a slightly larger density and sound speed than those in ambient fluid are considered. Initial particle distribution is assumed to be almost homogeneous at the considered intervals. The formation of concentration peaks in plane standing waves and on the axis of a cylindrical system is demonstrated; additional concentration along the axis is possible. The possibility of an opposite process, i.e., keeping particles stirred by periodic change of acoustic wavelength, is confirmed as well. Distribution and separation of microbubbles of different sizes in a standing wave is also studied. Examples of available experimental data illustrating the relevance of the theory are given.
Procedures for ambient-pressure and tympanometric tests of aural acoustic reflectance and admittance in human infants and adults
Authors: Keefe Douglas H. , Hunter Lisa L. , Feeney M. Patrick , Fitzpatrick Denis F.
Published: December 2015

Procedures are described to measure acoustic reflectance and admittance in human adult and infant ears at frequencies from 0.2 to 8 kHz. Transfer functions were measured at ambient pressure in the ear canal, and as down- or up-swept tympanograms. Acoustically estimated ear-canal area was used to calculate ear reflectance, which was parameterized by absorbance and group delay over all frequencies (and pressures), with substantial data reduction for tympanograms. Admittance measured at the probe tip in adults was transformed into an equivalent admittance at the eardrum using a transmission-line model for an ear canal with specified area and ear-canal length. Ear-canal length was estimated from group delay around the frequency above 2 kHz of minimum absorbance. Illustrative measurements in ears with normal function are described for an adult, and two infants at 1 month of age with normal hearing and a conductive hearing loss. The sensitivity of this equivalent eardrum admittance was calculated for varying estimates of area and length. Infant-ear patterns of absorbance peaks aligned in frequency with dips in group delay were explained by a model of resonant canal-wall mobility. Procedures will be applied in a large study of wideband clinical diagnosis and monitoring of middle-ear and cochlear function.
Psychometric functions for sentence recognition in sinusoidally amplitude-modulated noises
Authors: Shen Yi , Manzano Nicole K. , Richards Virginia M.
Published: December 2015

Listeners' speech reception is better when speech is masked by a modulated masker compared to an unmodulated masker with the same long-term root-mean-square level. It has been suggested that listeners take advantage of brief periods of quiescence in a modulated masker to extract speech information. Two experiments examined the contribution of such “dip-listening” models. The first experiment estimated psychometric functions for speech intelligibility using sentences masked by sinusoidally modulated and unmodulated speech-shaped noises and the second experiment estimated detection thresholds for a tone pip added at the central dip in the masker. Modulation rates ranging from 1 to 64 Hz were tested. In experiment 1 the slopes of the psychometric functions were shallower for lower modulation rates and the pattern of speech reception thresholds as a function of modulation rate was nonmonotonic with a minimum near 16 Hz. In contrast, the detection thresholds from experiment 2 increased monotonically with modulation rate. The results suggest that the benefits of listening to speech in temporally fluctuating maskers cannot be solely ascribed to the temporal acuity of the auditory system.
Resonant interaction of acoustic waves with subaqueous bedforms: Sand dunes in the South China Sea
Authors: Chiu Linus Y. S. , Chang Andrea Y. Y. , Benjamin Reeder D.
Published: December 2015

The large subaqueous sand dunes in the South China Sea are expected to produce the coupling of energy between acoustic normal modes. In this letter, resonant interaction between acoustic propagating modes and subaqueous bedforms are numerically investigated as a function of bedform wavelength, acoustic frequency and bedform packet length. The results demonstrate that bedform wavelength impacts acoustic mode coupling behavior, with the principal transfer of energy occurring between acoustic modes whose eigenvalue difference is equal to the peak value in the bedform wavenumber spectrum. The observed effect of wavelength is greater than that of acoustic frequency and bedform packet length.
Academic clinical research: Death by a thousand clicks
Authors: Stein C. Michael
Published: December 2015

Selected strategies can reduce the administrative burden on researchers and improve efficiency while still achieving clinical and regulatory goals.
Reprograming T
regs
to become tumor killers
Authors: Beswick Ellen J.
Published: December 2015

CD137 agonist induces T
regs
to become cytotoxic.
Impact of Anaerobiosis on Expression of the Iron-Responsive Fur and RyhB Regulons
Authors: Beauchene Nicole A. , Myers Kevin S. , Chung Dongjun , Park Dan M. , Weisnicht Allison M. , Keleş Sündüz , Kiley Patricia J.
Published: December 2015

Iron, a major protein cofactor, is essential for most organisms. Despite the well-known effects of O2on the oxidation state and solubility of iron, the impact of O2on cellular iron homeostasis is not well understood. Here we report that inEscherichia coliK-12, the lack of O2dramatically changes expression of genes controlled by the global regulators of iron homeostasis, the transcription factor Fur and the small RNA RyhB. Using chromatin immunoprecipitation sequencing (ChIP-seq), we found anaerobic conditions promote Fur binding to more locations across the genome. However, by expression profiling, we discovered that the major effect of anaerobiosis was to increase the magnitude of Fur regulation, leading to increased expression of iron storage proteins and decreased expression of most iron uptake pathways and several Mn-binding proteins. This change in the pattern of gene expression also correlated with an unanticipated decrease in Mn in anaerobic cells. Changes in the genes posttranscriptionally regulated by RyhB under aerobic and anaerobic conditions could be attributed to O2-dependent changes in transcription of the target genes: aerobic RyhB targets were enriched in iron-containing proteins associated with aerobic energy metabolism, whereas anaerobic RyhB targets were enriched in iron-containing anaerobic respiratory functions. Overall, these studies showed that anaerobiosis has a larger impact on iron homeostasis than previously anticipated, both by expanding the number of direct Fur target genes and the magnitude of their regulation and by altering the expression of genes predicted to be posttranscriptionally regulated by the small RNA RyhB under iron-limiting conditions.

IMPORTANCEMicrobes and host cells engage in an “arms race” for iron, an essential nutrient that is often scarce in the environment. Studies of iron homeostasis have been key to understanding the control of iron acquisition and the downstream pathways that enable microbes to compete for this valuable resource. Here we report that O2availability affects the gene expression programs of twoEscherichia colimaster regulators that function in iron homeostasis: the transcription factor Fur and the small RNA regulator RyhB. Fur appeared to be more active under anaerobic conditions, suggesting a change in the set point for iron homeostasis. RyhB preferentially targeted iron-containing proteins of respiration-linked pathways, which are differentially expressed under aerobic and anaerobic conditions. Such findings may be relevant to the success of bacteria within their hosts since zones of reduced O2may actually reduce bacterial iron demands, making it easier to win the arms race for iron.
Clinical characteristics, management and 1-year outcomes of patients with acute coronary syndrome in Iran: the Iranian Project for Assessment of Coronary Events 2 (IPACE2)
Authors: Kassaian Seyed Ebrahim , Masoudkabir Farzad , Sezavar Hashem , Mohammadi Mohammad , Pourmoghaddas Ali , Kojouri Javad , Ghaffari Samad , Sanaati Hamidreza , Alaeddini Farshid , Pourmirza Bahin , Mir Elham
Published: December 2015

Objectives

To assess contemporary data on characteristics, management and 1-year postdischarge outcomes in Iranian patients hospitalised with acute coronary syndrome (ACS).

Setting

11 tertiary care hospitals in 5 major cities in the Islamic Republic of Iran.

Participants

Patients aged ≥20 and ≤80 years discharged alive with confirmed diagnosis of ACS including ST-segment elevation myocardial infarction (STEMI), non-STEMI (NSTEMI) and high-risk unstable angina (HR-UA).

Primary and secondary outcome measures

Patients were followed up regarding the use of medications and the end points of the study at 1 month and 1 year after discharge. The primary end point of the study was 1-year postdischarge major adverse cardiac and cerebrovascular events (MACCEs), defined as mortality (cardiac and non-cardiac), ACS and cerebrovascular attack (stroke and/or transient ischaemic attack). The secondary end points were hospital admission because of congestive heart failure, revascularisation by coronary artery bypass grafting surgery or percutaneous coronary intervention (PCI), and major and minor bleeds.

Results

A total of 1799 patients (25.7% STEMI and 74.3% HR-UA/NSTEMI) discharged alive with confirmed diagnosis of ACS were included in the final analysis. During hospitalisation, the majority of the patients received aspirin (98.6%), clopidogrel (91.8%), anticoagulants (93.4%), statins (94.3%) and β-blockers (89.3%). Reperfusion therapy was performed in 62.6% of patients with STEMI (46.3% thrombolytic therapy and 17.3% primary PCI). The mean door-to-balloon and door-to-needle times were 82.9 and 45.6 min, respectively. In our study, 64.7% and 79.5% of the patients in HR-UA/NSTEMI and STEMI groups, respectively, underwent coronary angiography. During the 12 months after discharge, MACCEs occurred in 15.0% of all patients.

Conclusions

Our study showed that the composition of Iranian patients with ACS regarding the type of ACS is similar to that in developed European countries and is unlike that in developing countries of the Middle East and Africa. We found that our patients with ACS are treated with high levels of adherence to guideline-recommended in-hospital medications.
Effect of smoking on physical and cognitive capability in later life: a multicohort study using observational and genetic approaches
Authors: North Teri-Louise , Palmer Tom M , Lewis Sarah J , Cooper Rachel , Power Chris , Pattie Alison , Starr John M , Deary Ian J , Martin Richard M , Aihie Sayer Avan , Kumari Meena , Cooper Cyrus , Kivimaki Mika , Kuh Diana , Ben-Shlomo Yoav , Day Ian N M
Published: December 2015

Objectives

The observed associations between smoking and functional measures at older ages are vulnerable to bias and confounding. Mendelian randomisation (MR) uses genotype as an instrumental variable to estimate unconfounded causal associations. We conducted a meta-analysis of the observational associations and implemented an MR approach using the smoking-related single nucleotide polymorphism rs16969968 to explore their causal nature.

Setting

9 British cohorts belonging to the HALCyon collaboration.

Participants

Individual participant data on N=26 692 individuals of European ancestry (N from earliest phase analysed per study) of mean ages 50–79 years were available for inclusion in observational meta-analyses of the primary outcomes.

Primary outcomes

Physical capability, cognitive capability and cognitive decline. The smoking exposures were cigarettes per day, current versus ex-smoker, current versus never smoker and ever versus never smoker.

Results

In observational analyses current and ever smoking were generally associated with poorer physical and cognitive capability. For example, current smokers had a general fluid cognition score which was 0.17 z-score units (95% CI −0.221 to −0.124) lower than ex-smokers in cross-sectional analyses. Current smokers had a walk speed which was 0.25 z-score units lower than never smokers (95% CI −0.338 to −0.170). An MR instrumental variable approach for current versus ex-smoker and number of cigarettes smoked per day produced CIs which neither confirmed nor refuted the observational estimates. The number of genetic associations stratified by smoking status were consistent with type I error.

Conclusions

Our observational analysis supports the hypothesis that smoking is detrimental to physical and cognitive capability. Further studies are needed for a suitably powered MR approach.
Unintentional, non-fatal drowning of children: US trends and racial/ethnic disparities
Authors: Felton Heather , Myers John , Liu Gil , Davis Deborah Winders
Published: December 2015

Objective

The current study aimed to better understand trends and risk factors associated with non-fatal drowning of infants and children in the USA using two large, national databases.

Methods

A secondary data analysis was conducted using the National Inpatient Sample and the Nationwide Emergency Department Sample databases. The analytic sample (n=19 403) included children <21 years of age who had a diagnosis code for near-drowning/non-fatal drowning. Descriptive, χ2and analysis of variance techniques were applied, and incidence rates were calculated per 100 000 population.

Results

Non-fatal drowning incidence has remained relatively stable from 2006 to 2011. In general, the highest rates of non-fatal drowning occurred in swimming pools and in children from racial/ethnic minorities. However, when compared with non-Hispanic Caucasian children, children from racial/ethnic minorities were more likely to drown in natural waterways than in swimming pools. Despite the overall lower rate of non-fatal drowning among non-Hispanic Caucasian children, the highest rate of all non-fatal drowning was for non-Hispanic Caucasian children aged 0–4 years in swimming pools. Children who were admitted to inpatient facilities were younger, male and came from families with lower incomes.

Conclusions

Data from two large US national databases show lack of progress in preventing and reducing non-fatal drowning admissions from 2006 to 2011. Discrepancies are seen in the location of drowning events and demographic characteristics. New policies and interventions are needed, and tailoring approaches by age and race/ethnicity may improve their effectiveness.