bluuebunny/crossref_metadata_2025 huggingface dataset:
Possible mechanisms for long‐lasting potentiation of synaptic transmission in hippocampal slices from guinea‐pigs.
Authors: Andersen P , Sundberg S H , Sveen O , Swann J W , Wigström H
Published: December 2015

1. Long‐lasting potentiation of synaptic transmission was studied in the CA1 region of guinea‐pig hippocampal slices maintained in vitro. 2. Stimulating pulses were delivered alternately to two independent afferent pathways, stratum radiatum and stratum oriens. The presynaptic volleys and field e.p.s.p.s. were recorded from the same two layers, while an electrode in the pyramidal cell body layer recorded the population spike or in other experiments the extra‐ or intracellular potentials from a single pyramidal cell. 3. A short tetanus to either of the two input pathways produced a long‐lasting enhancement of the field e.p.s.p. as well as an increased size and a reduced latency of the population spike. This long‐lasting potentiation was observed for up to 110 min after tetanization. Extracellular unit recordings showed that this potentiation is accompanied by an increased probability of firing and a reduced firing latency. Intracellular recordings showed an increased e.p.s.p., through the increase was smaller and less regular than for the extracellular field e.p.s.p. 4. No corresponding changes were seen in the field potential responses to stimulation of the untetanized input path, or in the intracellularly measured soma membrane potential, resistance, or excitability. The latter two properties were measured by intracellular injection of current pulses. It is concluded that long‐lasting potentiation is specific to the pathway which has received the tetanization. 5. Following tetanization there was also a short‐lasting (usually 2‐4 min) depression, most often seen for the control pathway but sometimes visible on the tetanized side as well, superimposed on the potentiation. It is concluded that the short‐lasting depression is not confined to any particular pathway but is a generalized (unspecific) phenomenon.
A physiological analysis of subcortical and commissural projections of areas 17 and 18 of the cat.
Authors: Harvey A R
Published: December 2015

1. The corticotectal, corticothalamic and commissural projections of areas 17 and 18 of the cat have been examined using electrical stimulation techniques. 2. In both area 17 and area 18, almost all corticotectal neurones are C cells and have binocular receptive fields. Some of these cells respond equally well to both small moving spots and elongated stimuli, while others only respond to stimuli of restricted length (cf. Palmer & Rosenquist, 1974). Both types are highly direction‐selective. A third type of corticotectal C cell responds optimally to long edges or bars and shows only weak direction selectivity. Corticotectal cells generally have fast conducting axons and the majority are encountered in lamina V. About 25% of all cells recorded in lamina V can be antidromically activated from the superior colliculus. 3. Striate and parastriate cells efferent to the thalamus can have either S or C type receptive fields. Corticothalamic S cells are the most common type of efferent cell in lamina VI and have more slowly conducting axons than C cells. Efferent S cells are almost always direction‐selective and about half have binocular receptive fields. 4. It is suggested that there may be at least three subgroups within the corticothalamic cells: lamina V C cells project to the pulvinare complex (the same cells may also send axons to the superior colliculus), lamina VI C cells project to the perigeniculate nucleus and lamina VI S cells provide the cortical input to neurones within the lateral geniculate nucleus. 5. In contrast to the corticotectal and corticothalamic projections, the receptive fields of cells projecting through the corpus callosum forth a heterogenous group. All major striate and parastriate receptive field classes are efferent to the contralateral cortex. Their receptive field centres are located close to the vertical mid line and most cells respond best to stimuli moving towards the ipsilateral visual hemifield. Efferent neurones are mostly encountered in lamina III, within about 1mm either side of the 17‐18 border zone. 6. Cells orthodromically excited after commissural stimulation have mostly C or B type receptive fields. Unlike efferent callosal neurones, orthodromically activated cells are encountered up to 3 mm into area 18 and can have receptive fields located up to 9 degrees from the vertical mid line. 7. The results are discussed with regard to the possible functional significance of each of the corticofugal pathways.
Substance P: immunohistochemical localization and effect upon cat pial arteries in vitro and in situ.
Authors: Edvinsson L , McCulloch J , Uddman R
Published: December 2015

1. Nerve fibres containing substance P immunoreactivity were present in the adventitia and the adventitia‐media border of all cat cerebral arteries which were examined. Substance P immunoreactivity was most abundant in cerebral arteries from the rostral portion of the circle of Willis. 2. Substance P effected a dose‐dependent relaxation of feline middle cerebral arteries which had been contracted with prostaglandin F2 alpha. The maximum relaxation (16 +/‐ 0.3 mN) was achieved with substance P at a concentration of 10‐6 M. 3. In cats anaesthetized with alpha‐chloralose, the perivascular microinjection of substance P effected dose‐dependent increases in arteriolar calibre. The maximum increase in calibre (19 +/‐ 3%) was observed following the injection of 10(‐6) M‐substance P.
Simultaneous changes in the equilibrium potential and potassium conductance in voltage clamped Ranvier node in the frog.
Authors: Dubois J M
Published: December 2015

1. In voltage clamped myelinated nerve fibres, the K+ conductance has been calculated from current recordings obtained in low and high K+ media, taking into account the changes in EK resulting from accumulation of depletion of K+ ions near to nodal membrane. 2. At the end of a depolarization, the instantaneous K+ current reverses at a potential (instantaneous reversal potential) differing from the Nernst potential calculated using the external and internal bulk concentrations (theoretical Nernst potential). During a depolarization, EK, as estimated from the instantaneous reversal potential, changes continuously. This change depends on the size, the duration and the direction of the time dependent K+ current. The variation of EK is attributed to continuous changes in K+ concentration near the membrane during voltage pulses which turn on the K+ conductance. 3. The chord conductance [GK = IK/(E‐EK), as calculated using the instantaneous reversal potential values for EK, has been analysed as a function of time and membrane potential. As previously reported it increases with the initial K+ concentration in the external medium. 4. The time course of the K+ current depends on both the kinetics of the conductance increase and the rate of change in the driving force for K. The kinetics of the conductance increase can satisfactorily be described by a single exponential function following a delay after the onset of the depolarizing voltage clamp pulse. 5. This delay increases when the holding potential is made more negative. It decreases with membrane depolarization and it is independent of the external K+ concentration. At a given membrane potential, the turning on of the K+ conductance is found to be faster at high than at low external K+ concentrations. 6. At repolarization the turning off of the conductance cannot be described by a single exponential function. It is faster at low than at high external K+ concentrations. 7. The results suggest that the change in K+ conductance proceeds in a multi‐step transition or (and) that the K+ conductance is determined by several types of K+ channels.
The effect of vasopressin on extracellular cation concentrations and muscle resting potentials in the rat.
Authors: Gartside I B , Jones A M , Laycock J F , Walter S J
Published: December 2015

1. The Na+ and K+ concentrations in plasma and cerebrospinal (c.s.f.), resting potentials in skeletal muscle fibres, cardiac beat to beat intervals and 90% repolarization times were measured in Long Evans rats (parent strain controls) and in Brattleboro rats with hypothalamic diabetes insipidus (DI). 2. Cation concentration measurements confirmed previous observations that Brattleboro DI rats are mildly hypokalaemic compared with rats of the parent Long Evans strain, and indicated that the c.s.f. [Na+] is significantly raised in the former group of animals while the [K+] in the c.s.f. samples is similar in the two groups. 3. The mean resting potential of deep skeletal muscle fibres in Brattleboro DI rats was significantly more negative than the corresponding value in the Long Evans rats, and this finding was in close agreement with the difference observed for the calculated K+ equilibrium potentials in the two groups of animals. 4. The beat to beat intervals and the 90% repolarization times of cardiac action potentials were also determined in Brattleboro DI and Long Evans rats, and the mean values for both variables were significantly shorter in the former group of animals. 5. The administration of Pitressin by subcutaneous injection (500‐100 mu./24 hr) to Brattleboro rats abolished the hypokalaemia and the hyperpolarization of skeletal muscle fibre membranes but had no significant effect on c.s.f. cation concentrations. 6. The present findings suggest that the absence of vasopressin in the Brattleboro DI rats results in a hyperpolarization of muscle cell membranes, and in changes in the cardiac action potential. These effects may be partly related to the mild hypokalaemia present in these animals.
Secretin release from the isolated, vascularly perfused pig duodenum.
Authors: Holst J J , Lauritsen K , Jensen S L , Nielsen O V , Schaffalitzky de Muckadell O B
Published: December 2015

1. A method for the isolation and vascular perfusion of the porcine pancreas and duodenum was developed. 2. The oxygen consumption of the whole preparation was similar to that of the pancreas alone, and since the duodenal arteriovenous oxygen deficit was similar to that of the total preparation, it was concluded that the duodenum respired adequately. 3. The duodenum rapidly absorbed luminally administered radioactive glucose, and this absorption was strongly inhibited by ouabain and phloridzin. 4. The duodenum secreted secretin rapidly in response to hydrochloric acid, but did not respond to any other luminal stimuli, including lipids, proteins, carbohydrates and bile. Neither was secretin release stimulated by intra‐arterially injected acetylcholine. 5. By gel permeation chromatography the release immunoreactive secretin behaved identically to pure natural secretin, indicating that the tissue form and the circulating form have identical molecular size. 6. It is concluded that this model offers an unique opportunity to study the endocrine secretion of the duodenum.
Cellular mechanisms of ion transport associated with osmotic gradients in rat small intestine.
Authors: Decker R A , Jackson M J , Tai Y H
Published: December 2015

1. The electrical potential difference, short‐circuit current, tissue conductance, and fluxes of sodium and chloride were measured in rat small intestine in an in vitro chamber preparation in the presence and absence of 100 mM‐mannitol on either the mucosal or serosal surface. 2. Mucosal mannitol generally decreased potential difference, short‐circuit current, and tissue conductance while serosal mannitol increased the electrical variables. 3. Mucosal mannitol decreased unidirectional movement of sodium and chloride but did not change the net transport of these ions. The change in short‐circuit current was therefore ascribed to changes in fluxes of ions other than sodium and chloride. 4. Serosal mannitol increased the unidirectional fluxes of sodium, but not the new transport of this ion. The transport of chloride increased only in the serosal to mucosal direction yielding a net secretion of chloride equal to the change in short‐circuit current. 5. The changes in potential difference and short‐circuit current caused by mucosal mannitol were dependent on the presence of sodium. The changes due to serosal mannitol were dependent on both sodium and chloride. 6. Changes in undirectional transport of ions, small non‐electrolytes, and water due to an osmotic gradient were attributed to changes in the dimension of the lateral intercellular spaces observed in earlier studies. 7. No evidence suggesting that the electrical changes due to the mannitol gradients could be attributed to diffusive or convective flows of fluid, but instead the changes were ascribed to perturbations in the cellular transport mechanisms.
Pancreatic endocrine responses to physiological changes in plasma neurotensin concentration in the calf.
Authors: Blackburn A M , Bloom S R , Edwards A V
Published: December 2015

1. Plasma neurotensin concentration was found to increase by between 3 and 18 pmol/l 20 min after feeding in conscious 2‐6 week old calves. 2. Synthetic bovine neurotensin was infused I.V. at a dose which reproduced the rise in the plasma concentration (1 pmol. kg‐1 min‐1), in calves of the same age, which were also receiving a continuous I.V. infusion of glucose (0.03 mmol. kg‐1. min‐1) to mimic alimentary hyperglycaemia. Under these conditions neurotensin caused a significant rise in the mean concentration of both insulin and pancreatic polypeptide (PP), but not that of glucagon, in the arterial plasma. 3. The rise of plasma insulin concentration, but not that of PP, in response to the same dose of neurotensin was strongly potentiated during infusions of exogenous amino acids. There was also a significant rise in plasma glucagon concentration in response to neurotensin in the calves given amino acids. 4. It is concluded that neurotensin is a physiological incretin in the calf.
Sodium current in single rat heart muscle cells.
Authors: Brown A M , Lee K S , Powell T
Published: December 2015

1. Rapid inward Na current (INa) was studied in isolated cells from rat ventricular myocardium by a double‐suction‐pipette voltage clamp technique. All experiments were carried out at 20‐22 degrees C. 2. INa elicited by single depolarizing voltage steps from a holding potential, VH, of ‐80 mV had a threshold between ‐70 and ‐60 mV and was maximal at ‐30 to ‐20 mV. Peak currents in Krebs‐Ringer solution containing 145 mM Na were of the order 0.9‐1.8 mA cm‐2, assuming an average cell surface area of 8000 square micrometers. 3. The reversal potential for INa was predicted by the Nernst equation for external Na in the range 1.45‐145 mM with 16 mM‐Na solution perfusing the interior of the cell. 4. Instantaneous I‐V plots were linear for potentials of ‐100 to + 10 mV. Maximum Na conductance (‐gNa) was calculated to be 25 mS cm‐2 in 145 mM‐Na solutions and gNa was constant for potentials positive to ‐10 mV. 5. INa activated with a time constant of 0.7 msec at ‐55 mV, decreasing to 100 microsec on depolarizations positive to + 10 mV. 6. Two time constants (tau h1, tau h2) were required to describe INa inactivation during a maintained depolarization, with tau h2 three to four times as long as tau h1. tau h1 was about 2 msec at ‐50 mV, decreasing to 0.9 msec at ‐10 mV. 7. The time course for recovery of INa from inactivation also exhibited two time constants (tau r1, tau r2), with the longer tau r2 having a maximum value of the order 100 msec in the potential range ‐60 to ‐80 mV. 8. INa in isolated rat cardiac cells has a low sensitivity to tetrodotoxin, requiring a concentration of 30 micrometers for complete blockade.
The early circulatory and ventilatory response to voluntary and electrically induced exercise in man.
Authors: Adams L , Guz A , Innes J A , Murphy K
Published: December 2015

1. The ventilatory and circulatory responses to electrically induced leg exercise (EEL) were studied in seven normal subjects and compared with the responses to performing the same exercise voluntarily (EV). 2. EEL was produced by surface electrode stimulation of the quadriceps and hamstring muscle groups. This produced a push‐relax pattern of exercise against a spring load and was free of any pain or discomfort. EV, at the same level, was achieved by subjects copying a display of timing and force information on a storage oscilloscope. 3. Cardiac output was estimated using validated Doppler ultrasound measurements of the velocity in the ascending aorta, combined with an estimate of aortic cross‐sectional area using M‐mode echocardiography. 4. Data from EV and EEL exercise runs were matched, within subjects, for the increase in oxygen consumption during the first 30 s of exercise; there were no significant differences between the resting states prior to either form of exercise. 5. The first ten beats of exercise were used to study the circulatory on‐transient. The cardiac output responses to both EV and EEL were similar; however, in EV alone there was an initial significant drop in stroke volume and a slightly greater rise in heart rate. 6. The first five breaths of the response were used to study the ventilatory on‐transient, and by measuring cardiac output, stroke volume and heart rate throughout each breath, the relationship between circulatory and ventilatory variables could be assessed. Ventilation showed a significantly greater rise at the onset of exercise during EV than during EEL; PET,CO2 (end‐tidal CO2 pressure) showed small but significant falls for both EV and EEL. 7. The circulatory changes on a breath‐by‐breath basis are similar for EV and EEL although the ventilatory changes differ. In both EV and EEL the average increase in ventilation at the onset of exercise is proportionally greater than the average increases in cardiac output. Individual exercise runs show no particular relationship between circulatory and ventilatory change. 8. The results provide no support in man during mild leg exercise for a 'cardiodynamic' drive to breathing.
Effects of caffeine on intracellular calcium concentrations in frog skeletal muscle fibres.
Authors: Konishi M , Kurihara S
Published: December 2015

1. The mechanism of twitch potentiation by caffeine was studied in single muscle fibres dissected from m. tibialis anterior of Rana temporaria. Fibres were injected with a Ca2+‐sensitive photo‐protein, aequorin, and the resultant light signal and tension were simultaneously recorded. 2. In twitch responses triggered every 60 s, peaks of light and tension were maintained at a constant level. Low concentrations of caffeine (0.2‐0.4 mM) potentiated twitch tension accompanied by a slight increase in light signal. 3. Although peak twitch tension was dose‐dependently potentiated by caffeine, light peaks were suppressed at relatively higher concentrations of caffeine (0.6‐1.5 mM) with prolonged decay of the light and tension signals. 4. Light intensity in the resting muscle (resting glow) was elevated by caffeine (0.2‐1.5 mM) dose‐dependently without detectable tension development. This effect of caffeine was suppressed by 0.5‐1.0 mM‐procaine or 10 mM‐adenine, inhibitors of Ca2+‐induced Ca2+ release. 5. In caffeine‐treated preparations, peaks of light and tension were augmented by application of procaine (0.5‐1.0 mM). Adenine (10 mM) affected the light signal in essentially the same way as procaine, but the effect varied from fibre to fibre. 6. From these results, the following hypothesis is proposed: low concentrations of caffeine directly induce Ca2+ release from sarcoplasmic reticulum (s.r.) in in the resting state, and facilitates Ca2+ release from s.r. induced by the action potential during twitch. At relatively higher concentrations of caffeine (0.6‐1.5 mM), rise of resting [Ca2+]i (intracellular free Ca2+ concentration) before activation might be an important factor in twitch potentiation by caffeine. If the rise of resting [Ca2+]i induced by caffeine is inhibited by procaine and the content of Ca2+ in s.r. is well maintained, caffeine could facilitate Ca2+ release by depolarization and thus potentiate twitch tension.
In utero ventilation with oxygen augments left ventricular stroke volume in lambs.
Authors: Morton M J , Pinson C W , Thornburg K L
Published: December 2015

1. In order to determine mechanisms for increased stroke volume at birth, left ventricular function was investigated in eight fetal lambs during in utero pulmonary ventilation. At surgery fetuses were prepared with a tracheal tube, aortic electromagnetic flow sensor, and carotid, jugular, pericardial and left atrial catheters. 2. After 8.3 +/‐ 1.5 (mean +/‐ S.D.) post‐surgery days and at 137 +/‐ 3 days gestation, haemodynamic values were obtained before and during pulmonary ventilation in utero. 3. During ventilation, O2 content increased from 7.3 +/‐ 2.1 to 14.7 +/‐ 2.7 ml dl‐1 (P less than 0.001), right atrial pressure from 3.0 +/‐ 1.3 to 4.5 +/‐ 1.6 mmHg (P less than 0.05), left atrial pressure from 2.5 +/‐ 1.2 to 10.2 +/‐ 3.7 mmHg (P less than 0.001), left ventricular stroke volume from 1.1 +/‐ 0.4 to 1.9 +/‐ 1.2 ml kg‐1 (P less than 0.05), and heart rate from 160 +/‐ 21 to 183 +/‐ 11 beats min‐1 (P less than 0.05). 4. During O2 ventilation, left ventricular function curves relating stroke volume to left atrial pressure were shifted upward. 5. O2 ventilation produced rapid, reversible increases in left ventricular stroke volume which approximate increases in stroke volume at birth.
Release of 5‐hydroxytryptamine by pentagastrin and its role in the 'fade' of stimulated gastric secretion in cats.
Authors: Izzat A , Waton N G
Published: December 2015

1. The release of 5‐hydroxytryptamine (5‐HT) by pentagastrin and the 'fade' phenomenon seen in acid gastric secretion during a continuous intravenous infusion of pentagastrin have been studied in anaesthetized cats. 2. During an intravenous infusion of pentagastrin, acid secretion rose steeply to a maximum at 45 min. It was maintained at this rate for only 15‐30 min, after which it decreased gradually. Meanwhile there was a marked increase in the 5‐HT content of the plasma which reached a peak at 120 min and remained just below the peak concentration for the rest of the experiment. 3. Acid secretion due to an intravenous infusion of histamine on the other hand, steadily increased over the 3 h collection period. Meanwhile there was only a gradual small increase in the 5‐HT content of the plasma. 4. Whereas there was a continuous steady increase in acid secretion in response to an intravenous infusion of pentagastrin in cats pre‐treated with reserpine, acid secretion rose to a sharp peak and then decreased gradually when reserpinized cats were given a simultaneous infusion of 5‐HT along with the pentagastrin. 5. It is concluded that 5‐HT is released by pentagastrin and that it is responsible for the 'fade' phenomenon seen in acid secretion during infusions of pentagastrin, first of all augmenting acid secretion and then inhibiting it.
Post‐natal development of the retinal and cerebellar projections onto the lateral suprasylvian area in the cat.
Authors: Kato N , Kawaguchi S , Miyata H
Published: December 2015

1. Post‐natal development of the retinal and cerebellar projections onto the medial bank of the lateral suprasylvian visual area was examined by using the field potential method and, additionally, by the orthograde horseradish peroxidase method. 2. Optic nerve stimulation elicited a surface‐positive, depth‐negative field potential in the medial bank of the lateral suprasylvian area of adult cats. By contrast, in kittens younger than 3 weeks old, a surface‐negative, depth‐positive field potential was evoked. The response grew adult‐like by 1 month of age. Corticocortical response, activated by stimulation of cortical areas 17 and 18, underwent a similar developmental change. 3. Cerebellar stimulation evoked a surface‐negative, depth‐positive wave from birth up to adulthood. Thalamocortical afferents from the ventroanterior and ventrolateral nuclei of the thalamus to the medial bank of the lateral suprasylvian area, which is presumed to be responsible for this cerebellar response, terminate mostly in layer I in both new‐born kittens and adult cats. 4. The present results, and our previous morphological findings on the projections from the extrageniculate visual thalamus and visual cortical areas 17 and 18 onto the medial bank of the lateral suprasylvian area, were correlated with reference to the maturation of the neuronal circuit in the cortex.
An investigation into the neural regulation of calcium excretion by the rat kidney.
Authors: Johns E J , Manitius J
Published: December 2015

1. An investigation was undertaken to examine the action of the renal nerves on the reabsorption of calcium ions from the left kidney of sodium pentobarbitone anaesthetized rats. 2. Renal denervation had no effect on renal haemodynamics but increased urine flow, calcium excretion, absolute and fractional sodium excretions by 26% (P less than 0.02), 73% (P less than 0.02), 90% (P less than 0.001) and 82% (P less than 0.01), respectively, without affecting the calcium to sodium excretion ratio. In a group of animals which were similarly prepared but the renal nerves were not sectioned, neither renal blood flow, nor the excretion of water, calcium or sodium changed during the time course of the experiment although glomerular filtration rate increased significantly (P less than 0.05) by 19%. 3. Low rates (0.8‐1.5 Hz at 15 V, 0.2 ms) of renal nerve stimulation did not change renal haemodynamics but reduced urine flow by 31% (P less than 0.001), calcium excretion by 32% (P less than 0.001), sodium excretion by 32% (P less than 0.001) and fractional sodium excretion by 32% (P less than 0.01) while the calcium to sodium excretion ratio was unaffected. Renal nerve stimulation at 3‐5 Hz reduced renal blood flow by 15% (P less than 0.02), did not change glomerular filtration rate and reduced urine flow, calcium excretion, absolute and fractional sodium excretions by 35% (P less than 0.01), 30% (P less than 0.01), 32% (P less than 0.01) and 32% (P less than 0.05), respectively, while the calcium to sodium excretion ratio remained unchanged. 4. These data show that the renal nerves can modulate the excretion of calcium by a mechanism which is independent of renal haemodynamics and which may represent a direct action of the nerves on the calcium reabsorptive processes of the tubular cells. It remains to be determined whether this neural control of calcium reabsorption is a direct one or indirect via changes in sodium reabsorption.
Contact Angle Measurement of Liquid Hydrogen (LH2) in Stainless Steel and Aluminum Cells
Authors: Bellur Kishan , Konduru Vinaykumar , Kulshrestha Manan , Tyrewala Daanish , Medici Ezequiel , Allen Jeffrey S. , Choi Chang Kyoung , Hussey Daniel S. , Jacobson David C. , Leão Juscelino B. , McQuillen John , Hermanson James , Tamilarasan Arun
Published: December 2015

One of the key limitations to long-term space missions is to avoid propellant boil-off in a microgravity space environment. Even with the use of active and passive controls of propellants, boil off is inevitable. Long-term CFD simulations on propellant behaviors depend on evaporation/condensation coefficients (known as accommodation coefficients) which are in turn dependent upon the wetting characteristics. Phase change experiments were conducted in the BT-2 neutron imaging facility at the National Institute of Standards and Technology (NIST) by introducing vapor H2 in 10 mm Al6061 and SS316L test cells placed inside the 70mm ‘orange’ cryostat. Condensation is achieved by lowering the cryostat temperature below the saturation point and vice versa for evaporation. The high neutron cross-section of liquid H2 in comparison to both the vapor and the test cell materials allows for visualization of a distinct liquid-vapor interface. Multiple images are stacked to increase the signal-to-noise ratio and the meniscus edge is obtained by detecting the pixels with largest gradients in intensities at the liquid meniscus. The contact angle is obtained by curve fitting of the Young-Laplace equation to the detected meniscus. The contact angle for Al6061 and SS316 is found to be between 0° and 4°. The uncertainty arises from edge detection, magnification, and resolution limits of the neutron imaging setup. The test was conducted at a saturation temperature of 21K (1.215 bar). The results from the neutron experiments will be then used in conjunction with FEA thermal models and kinetic phase change models to extract accommodation coefficients.
Effect of Evaporation Temperature on the Performance of Organic Rankine Cycle in Near-Critical Condition
Authors: Wang Yuping , Ding Xiaoyi , Tang Lei , Weng Yiwu
Published: December 2015

Considering the large variations of working fluid's properties in near-critical region, this paper presents a thermodynamic analysis of the performance of organic Rankine cycle in near-critical condition (NORC) subjected to the influence of evaporation temperature. Three typical organic fluids are selected as working fluids. They are dry R236fa, isentropic R142b, and wet R152a, which are suited for heat source temperature from 395 to 445 K. An iteration calculation method is proposed to calculate the performance parameters of organic Rankine cycle (ORC). The variations of superheat degree, specific absorbed heat, expander inlet pressure, thermal efficiency, and specific net power of these fluids with evaporation temperature are analyzed. It is found that the working fluids in NORC should be superheated because of the large slope variation of the saturated vapor curve in near-critical region. However, the use of dry R236fa or isentropic R142b in NORC can be accepted because of the small superheat degree. The results also indicate that a small variation of evaporation temperature requires a large variation of expander inlet pressure, which may make the system more stable. In addition, due to the large decrease of latent heat in near-critical region, the variation of specific absorbed heat with evaporation temperature is small for NORC. Both specific net power and thermal efficiency for the fluids in NORC increase slightly with the rise of the evaporation temperature, especially for R236fa and R142b. Among the three types of fluids, dry R236fa and isentropic R142b are better suited for NORC. The results are useful for the design and optimization of ORC system in near-critical condition.
On a Scale-Invariant Model of Statistical Mechanics and the Laws of Thermodynamics
Authors: Sohrab Siavash H.
Published: December 2015

A scale-invariant model of statistical mechanics is applied to describe modified forms of zeroth, first, second, and third laws of classical thermodynamics. Following Helmholtz, the total thermal energy of the thermodynamic system is decomposed into free heat U and latent heat pV suggesting the modified form of the first law of thermodynamics Q = H = U + pV. Following Boltzmann, entropy of ideal gas is expressed in terms of the number of Heisenberg–Kramers virtual oscillators as S = 4 Nk. Through introduction of stochastic definition of Planck and Boltzmann constants, Kelvin absolute temperature scale T (degree K) is identified as a length scale T (m) that is related to de Broglie wavelength of particle thermal oscillations. It is argued that rather than relating to the surface area of its horizon suggested by Bekenstein (1973, “Black Holes and Entropy,” Phys. Rev. D, 7(8), pp. 2333–2346), entropy of black hole should be related to its total thermal energy, namely, its enthalpy leading to S = 4Nk in exact agreement with the prediction of Major and Setter (2001, “Gravitational Statistical Mechanics: A Model,” Classical Quantum Gravity, 18, pp. 5125–5142).
A Methodology for Determining Optimum Solar Tower Plant Configurations and Operating Strategies to Maximize Profits Based on Hourly Electricity Market Prices and Tariffs
Authors: Guédez Rafael , Topel Monika , Conde Inés , Ferragut Francisco , Callaba Irene , Spelling James , Hassar Zhor , Perez-Segarra Carlos David , Laumert Björn
Published: December 2015

The present study analyzes the influence that market conditions have on determining optimum molten salt solar tower plants with storage that maximizes profits (in terms of plant configuration, sizing, and operation) for a location in South Africa. Three different scenarios based on incentive programs and local wholesale electricity prices are considered. A multi-objective optimization modeling approach was followed, showing the tradeoff curves between minimizing investment and maximizing profits when varying critical size-related parameters (such as nameplate capacity, solar multiple (SM), and storage capacity) together with power-cycle design and operating specifications including dynamic startup curves and different storage dispatchability strategies. Results are shown by means of a comparative analysis between optimal plants found for each scenario, highlighting the value that storage has under the current two-tier tariff scheme and the relevance of designing a suitable policy for technology development. Finally, a final analysis is performed with regard to the indicators used for economic evaluation of power plants, by comparing the differences between optimum designs found when using the levelized cost of electricity (LCoE) solely as performance indicator instead of cash-flows and profit-based indicators, such as the internal rate of return (IRR).
Aggressive Flight With Quadrotors for Perching on Inclined Surfaces
Authors: Thomas Justin , Pope Morgan , Loianno Giuseppe , Hawkes Elliot W. , Estrada Matthew A. , Jiang Hao , Cutkosky Mark R. , Kumar Vijay
Published: December 2015

Micro-aerial vehicles (MAVs) face limited flight times, which adversely impacts their efficacy for scenarios such as first response and disaster recovery, where it might be useful to deploy persistent radio relays and quadrotors for monitoring or sampling. Thus, it is important to enable micro-aerial vehicles to land and perch on different surfaces to save energy by cutting power to motors. We are motivated to use a downward-facing gripper for perching, as opposed to a side-mounted gripper, since it could also be used to carry payloads. In this paper, we predict and verify the performance of a custom gripper designed for perching on smooth surfaces. We also present control and planning algorithms, enabling an underactuated quadrotor with a downward-facing gripper to perch on inclined surfaces while satisfying constraints on actuation and sensing. Experimental results demonstrate the proposed techniques through successful perching on a glass surface at various inclinations, including vertical.
Practical approach to modeling e-beam lithographic process from SEM images for minimization of line edge roughness and critical dimension error
Authors: Guo Rui , Lee Soo-Young , Choi Jin , Park Sung-Hoon , Shin In-Kyun , Jeon Chan-Uk
Published: December 2015

Two main factors which limit the minimum feature size and the maximum circuit density achievable by electron-beam (e-beam) lithography are the line edge roughness (LER) and the proximity effect. Since the LER is caused by the stochastic nature of the exposing and development processes, it does not scale with the feature size. Therefore, reducing the LER is essential as the feature size continues to decrease. Accurate modeling of the LER and the proximity effect analytically or via simulation for their minimization is either difficult or costly in many cases. In this study, a practical method for extracting the essential information from SEM images, needed to characterize the e-beam lithographic process, and an effective method for minimizing the LER and critical dimension error based on the extracted information have been developed. The main objective is that the methods utilize only the information extracted from SEM images without having to know the complete setup of e-beam lithographic process. It has been shown that they have a good potential to be further developed into practical and useful tools.
Reliability and Validity of Physical Activity Instruments Used in Children and Youth with Physical Disabilities: A Systematic Review
Authors: White Lauren , Volfson Zlata , Faulkner Guy , Arbour-Nicitopoulos Kelly
Published: December 2015

Research often characterizes children and youth with physical disabilities as less physically active than their typically developing peers. To inform the development and evaluation of future interventions, it is important to identify the most accurate methods for assessing physical activity behavior in this population. The objectives of this review were 1) to identify the self-report and objective instruments used to examine habitual physical activity behavior within this population and 2) to determine the reliability and validity of these instruments. Following a standardized protocol, a systematic review was conducted using six electronic databases and a range of search terms. Fifty studies (N = 2,613; Mage = 11.3 ± 2.6 years; 53% male) were included. Seven disability groups were examined, with the majority of studies focused on cerebral palsy (64%) and juvenile arthritis (20%). Poor to good reliablity and weak validity were found among the self-report instruments such as questionnaires and activity diaries. Good to excellent reliability and validity were established for the objective instruments such as activity monitors (e.g., accelerometers, pedometers). Further research is warranted among physical disability groups other than cerebral palsy, and in establishing reliability and validity of self-report physical activity instruments specific to these target groups.
Maturity Status Does Not Exert Effects on Aerobic Fitness in Soccer Players After Appropriate Normalization for Body Size
Authors: Cunha Giovani Dos Santos , Vaz Marco Aurélio , Geremia Jeam Marcel , Leites Gabriela T. , Baptista Rafael Reimann , Lopes André Luiz , Reischak-Oliveira Álvaro
Published: December 2015

The present study investigated the effects of pubertal status on peak oxygen uptake (VO2peak), respiratory compensation point (RCP), and ventilatory threshold (VT) in young soccer players using different body size descriptors. Seventy-nine soccer players (14 prepubescent, 38 pubescent and 27 postpubescent) participated in this study. A maximal exercise test was performed to determine the VO2peak, RCP, and VT. Ultrasonography was used to measure lower limb muscle volume (LLMV). LLMV (mL-b) was rated as the most effective body size descriptor to normalize VO2peak (mLO2•mL-0.43•min-1), RCP (mLO2•mL-0.48•min-1), and VT (mLO2•mL-0.40•min-1). The values of VO2peak, RCP, and VT relative to allometric exponents derived by LLMV were similar among groups (p > .05; 0.025 < η2 < 0.059) when the effect of chronological age was controlled. Allometric VO2peak, RCP, and VT values were: 100.1 ± 7.9, 107.5 ± 9.6, and 108.0 ± 10.3 mLO2.mL-0.43•min-1; 51.8 ± 5.3, 54.8 ± 4.7, and 57.3 ± 5.8 mLO2•mL-0.48•min-1; and 75.7 ± 7.1, 79.4 ± 7.0, and 80.9 ± 8.3 mLO2•mL-0.40•min-1 for prepubertal, pubertal, and postpubertal groups, respectively. Maturity status showed no positive effect on VO2peak, RCP, and VT when the data were properly normalized by LLMV in young soccer players. Allometric normalization using muscle volume as a body size descriptor should be used to compare aerobic fitness between soccer players heterogeneous in chronological age, maturity status, and body size.
Reliability and Construct Validity of Yo-Yo Tests in Untrained and Soccer-Trained Schoolgirls Aged 9–16
Authors: Póvoas Susana C. A. , Castagna Carlo , Soares José Manuel da Costa , Silva Pedro , Coelho-e-Silva Manuel , Matos Fernando , Krustrup Peter
Published: December 2015

Purpose:

The reliability and construct validity of three age-adapted-intensity Yo-Yo tests were evaluated in untrained (n = 67) vs. soccer-trained (n = 65) 9- to 16-year-old schoolgirls.

Methods:

Tests were performed 7 days apart for reliability (9- to 11-year-old: Yo-Yo intermittent recovery level 1 children’s test; 12- to 13-yearold: Yo-Yo intermittent endurance level 1; and 14- to 16-year-old: Yo-Yo intermittent endurance level 2).

Results:

Yo-Yo distance covered was 40% (776 ± 324 vs. 556 ± 156 m), 85% (1252 ± 484 vs. 675 ± 252 m) and 138% (674 ± 336 vs. 283 ± 66 m) greater (p ≤ .010) for the soccer-trained than for the untrained girls aged 9–11, 12–13 and 14–16 years, respectively. Typical errors of measurement for Yo-Yo distance covered, expressed as a percentage of the coefficient of variation (confidence limits), were 10.1% (8.1–13.7%), 11.0% (8.6–15.4%) and 11.6% (9.2–16.1%) for soccer players, and 11.5% (9.1–15.8%), 14.1% (11.0–19.8%) and 10.6% (8.5–14.2%) for untrained girls, aged 9–11, 12–13 and 14–16, respectively. Intraclass correlation coefficient values for test-retest were excellent (0.795–0.973) in both groups. No significant differences were observed in relative exercise peak heart rate (%HRpeak) between groups during test and retest.

Conclusion:

The Yo-Yo tests are reliable for determining intermittent-exercise capacity and %HRpeak for soccer players and untrained 9- to 16-year-old girls. They also possess construct validity with better performances for soccer players compared with untrained age-matched girls, despite similar %HRpeak.
Morphologic Features of the “Athlete’s Heart” in Children: A Contemporary Review
Authors: Rowland Thomas
Published: December 2015

Recognizing the cardiac features of athletically trained children bears importance for health care providers and exercise physiologists alike. This literature review reveals that ventricular enlargement and/or hypertrophy are commonly observed in studies of pre- and early-adolescent endurance athletes, yet the magnitude of these features is less than that described in adult athletes. Moreover, the upper range of values in child athletes is sufficiently small that clinical confusion with findings mimicking those in individuals with heart disease should not be expected to occur. In contrast to sex differences in the “athlete’s heart” in adults, cardiac structural findings in child athletes are similar in males and females. The extent that cardiac features observed in trained child athletes reflect a response to training or are influenced by genetic preselection remains uncertain.
Implantable synthetic cytokine converter cells with AND-gate logic treat experimental psoriasis
Authors: Schukur Lina , Geering Barbara , Charpin-El Hamri Ghislaine , Fussenegger Martin
Published: December 2015

Implantable designer cells sense proinflammatory cytokines and coordinate production and delivery of anti-inflammatory molecules to attenuate psoriasis in mice.
The 20
S
proteasome core, active within apoptotic exosome-like vesicles, induces autoantibody production and accelerates rejection
Authors: Dieudé Mélanie , Bell Christina , Turgeon Julie , Beillevaire Deborah , Pomerleau Luc , Yang Bing , Hamelin Katia , Qi Shijie , Pallet Nicolas , Béland Chanel , Dhahri Wahiba , Cailhier Jean-François , Rousseau Matthieu , Duchez Anne-Claire , Lévesque Tania , Lau Arthur , Rondeau Christiane , Gingras Diane , Muruve Danie , Rivard Alain , Cardinal Héloise , Perreault Claude , Desjardins Michel , Boilard Éric , Thibault Pierre , Hébert Marie-Josée
Published: December 2015

Exosome-like vesicles containing an active 20
S
proteasome core contribute to autoimmunity and vascular allograft inflammation.
Mystery of a cryptogenic stroke solved by an abdominal angiogram
Authors: Sundar Kaushik , Venkatasubramanian Shankar , Umaiorubahan Meenakshisundaram , Cannigaiper Velmurugendran
Published: December 2015

Despite advances in the field of imaging and diagnostics, the incidence of cryptogenic stroke is still around 30–40% in modern stroke databases. Our patient presented with recurrent midbrain infarcts over 3 years and was initially labelled as a patient with cryptogenic stroke. His blood investigations were normal, work up for autoimmune disorders was negative, CT brain angiogram was normal and a two-dimensional echo showed a small patent foramen ovale with a left to right shunt. He later presented with a right perinephric haematoma and an abdominal angiogram revealed multiple microaneurysms of the renal arteries, coeliac trunk and the mesenteric arterial system. The feeding renal artery was embolised. A diagnosis of polyarteritis nodosa was made. The patient was subjected to digital subtraction angiography of neck and intracranial vessels, which revealed multiple microaneurysms in internal and external carotid artery territory. He was discharged with steroids and azathioprine.
Tumefactive demyelination presenting during bevacizumab treatment
Authors: Rice Claire M , Rossiter David , Fehmi Janev , Stevens James C , Renowden Shelley A , Cohen Nicki , Bailey Clare , Scolding Neil J
Published: December 2015

We report the emergence of tumefactive demyelination during treatment with intravitreal bevacizumab (Avastin). This is of particular significance given that bevacizumab is currently being assessed as a potential treatment option for neuromyelitis optica, another demyelinating condition.
Right ventricular failure due to late embolic RV infarction during continuous flow LVAD support
Authors: Plymen Carla , Pettit Stephen James , Tsui Steven , Lewis Clive
Published: December 2015

This report describes a 63-year-old man with a dilated cardiomyopathy, who was supported with a continuous flow left ventricular assist device (LVAD), and on the waiting list for heart transplantation. After a long period of stability, he presented with recurrent ventricular tachycardia and rapidly developed progressive right ventricular (RV) failure. He required implantation of a temporary RV assist device to regain stability and subsequently underwent urgent heart transplantation. The explanted heart showed multiple areas of ischaemic damage to the RV myocardium, but there was no significant underlying coronary artery disease. It appears that the ventricular arrhythmias and subsequent RV failure were due to an embolic event in the territory of the right coronary artery. The case highlights that coronary embolism is a rare cause of RV failure during LVAD support and demonstrates the utility of temporary RV assist device support as a bridge to heart transplantation.
Definitive use of external fixation for pelvic ring injuries (open book/APC2) in pregnancy
Authors: Stohlner V , Gill J R , Murphy C G , Carrothers A D
Published: December 2015

Pelvic fractures in pregnancy are rare, resulting in a paucity of evidence-based management. We describe a case of open book pelvic injury in a 32-year-old woman in her third trimester of pregnancy. She was successfully managed with a supra-acetabular external fixator, which allowed the safe delivery of a healthy baby boy at 34 weeks, via caesarean section. The external fixator was removed postpartum, when the pelvis was deemed stable, and mother and baby both continue to do well. This is the only case in the literature that demonstrates the successful use of external fixation for pelvic injuries in pregnancy.