bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of degenerating axon pathways in regeneration of mouse soleus motor axons.
Authors: Brown M C , Hopkins W G
Published: December 2015

1. The recovery of tension in mouse soleus was assayed 1‐5 days after crushing the extramuscular nerve in muscles which had been previously either denervated by nerve crush, partly denervated by spinal nerve root section, or paralysed by I.M. injection of botulinum toxin. Recovery of tension following nerve crush in contralateral control muscles from the same mice was also measured. The muscles were then stained with zinc iodide‐osmium and examined in the light microscope. 2. Recovery in control muscles began at about 50 hr after crush and was nearly complete by 5 days. Recovery began at about 50 hr after crush and was nearly complete by 5 days. Recovery began about 10 hr earlier and was more rapid in muscles denervated by crushing the muscle nerve 4 days before recrushing at the same site. 3. Paralysis 12 days earlier by intramuscular injection of botulinum toxin did not enhance recovery after nerve crush. The axons remained following partial denervation 6 days before nerve crush also regenerated at a rate similar to controls. 4. It is concluded that (1) nerves regenerate more quickly down a pre‐degenerated pathway, (2) chromatolysis does not significantly enhance reinnervation, and (3) each motor axon regenerating after a crush is constrained to follow its own denervated pathway back into the muscle. 5. Histology was consistent with these conclusions, and also showed that end‐plates in control muscles reinnervated after short periods of denervation were normal in appearance and possessed little "escaped' nerve growth. This was in contrast to end‐plates which had been regenerated in muscle after a preceding nerve crush, botulinum toxin paralysis or partial denervation. This suggests that growth from nerve terminals is controlled locally within a muscle.
The effects of digital nerve stimulation on the firing of motor units in human first dorsal interosseous muscle.
Authors: Datta A K , Stephens J A
Published: December 2015

1. The effect of cutaneous stimulation on the firing of single motor units has been studied during voluntary contractions in human first dorsal interosseous muscle. 2. Electrical stimulation of the index finger at 3 x threshold for perception reduced the firing rate of most units recruited at voluntary contraction strengths less than 1.5 N and increased the firing rate of all units recruited at contraction strengths greater than 1.5 N. The firing rate of all slow twitch units (contraction time greater than 75 msec) was reduced. The behaviour of fast twitch units was mixed but at this stimulus strength all units recruited at contraction strengths greater than 1.5 N had their firing rate increased. 3. Tested at different stimulus strengths, the stronger the stimulus the more the firing rate of low threshold units was reduced. The firing rate of units recruited at high contraction strength was increased by weak stimuli but reduced by strong stimuli. 4. It is concluded that stimulation of the index finger shifts the weighting of synaptic input associated with a voluntary contraction to favour the activity of the more powerful fast twitch motor units in first dorsal interosseous muscle.
Effect of urinary pH and urine flow rate on prostaglandin E2 and kallikrein excretion by the conscious dog.
Authors: Filep J , Földes‐Filep E
Published: December 2015

1. The effects of urine flow rate and urinary pH on renal prostaglandin E2 (PGE2) and kallikrein excretion were investigated in conscious dogs during water deprivation followed by rehydration and under conditions which altered urine pH, but caused similar change in salt and water excretion. 2. When water‐restricted dogs were rehydrated in two steps by gavage giving the animals tap water, urine flow increased by 22‐ and 63‐fold with a concomitant increase in PGE2 excretion by 100 and 318%, respectively; whereas urinary kallikrein excretion and urine pH did not change significantly. 3. Oral administration of isotonic sodium chloride solution increased urine flow as well as electrolyte excretion without altering urine pH (6.90 +/‐ 0.26) and PGE2 excretion. 4. When urine was made alkaline (pH 7.79 +/‐ 0.09) by oral sodium bicarbonate, urine flow and electrolyte excretion were similar to those observed after oral sodium chloride, while renal PGE2 excretion increased by 66% (P less than 0.05). 5. When urine was made acidic (pH 5.31 +/‐ 0.14) by oral ammonium chloride, urine flow and electrolyte excretion were similar to the values seen after oral sodium chloride. Urinary PGE2 excretion, however, was reduced by 46% (P less than 0.05). 6. After oral fluid loads a positive correlation could be detected between urine pH and urinary PGE2 excretion (r = 0.854, P less than 0.001). 7. Urinary kallikrein excretion was not significantly altered by any of the three interventions mentioned above. 8. The present results suggest that, in conscious dogs, urine flow as well as urine pH are important determinants of urinary PGE2 excretion rates, but not of kallikrein excretion.
Intracellular pH in sheep Purkinje fibres and ferret papillary muscles during hypoxia and recovery.
Authors: Ellis D , Noireaud J
Published: December 2015

1. The changes of intracellular pH (pHi) of papillary muscles from ferret and Purkinje fibres from sheep heart during hypoxia and recovery from hypoxia were recorded with pH‐sensitive micro‐electrodes filled with neutral H+ carrier. 2. Hypoxia was produced by replacement of O2 with N2 in the superfusing solutions. When oxidative phosphorylation was prevented, developed tension fell within 20 min to about 16 and 21% of its control value for papillary muscle and Purkinje fibres respectively. On restoration of O2, recovery of developed tension in ferret papillary muscle is preceded by a transient additional decrease. 3. In ferret papillary muscle, the pHi first increased by a mean value of 0.11 pH units after 3 min hypoxia, then decreased by about 0.24 pH units after 20 min. In sheep Purkinje fibres, the initial alkalosis was small or absent, and after 5‐9 min, the pHi started to fall reaching 0.17 pH units after 20 min of hypoxia. On return to oxygenated solution, a transient additional intracellular acidification occurred. This acidification reached its peak of 0.31 pH units in papillary muscle and of 0.13 pH units in Purkinje fibres. In both preparations hypoxia was accompanied by a depolarization of a few millivolts. 4. The presence of cyanide (1‐2 mM) or fluorodinitrobenzene (20‐40 microM) prevented the additional intracellular acidification occurring on return to oxygenated solution. Removal of cyanide itself produced a transient but smaller and slower acidification. 5. On both preparations, exposure to a Tyrode solution containing 10 mM‐L‐lactate produced a transient intracellular acidification. After recovery from this acidification the acidification produced by hypoxia was increased without affecting the extra acidification on reintroduction of O2. 6. After reduction of the rate of glycolysis by removal of glucose and application of 2‐deoxyglucose, the transient intracellular acidification, occurring on return to oxygenated solution after hypoxia, was inhibited in both preparations. In ferret papillary muscle, insulin (100 mU/ml) potentiated the changes of pHi occurring during hypoxia. 7. Using Na+‐sensitive glass micro‐electrodes it was found that the intracellular Na+ activity rose slightly during the later stages of hypoxia and rose transiently on readdition of O2. These results are consistent with a Na+‐H+ exchange being stimulated by acidosis. 8. The origins of the pH changes during and after hypoxia are discussed as are the differences between the responses of sheep Purkinje fibres and ferret papillary muscle.
Presynaptic action of neuropeptide Y in area CA1 of the rat hippocampal slice.
Authors: Colmers W F , Lukowiak K , Pittman Q J
Published: December 2015

1. Neuropeptide tyrosine (neuropeptide Y, NPY), a recently isolated endogenous brain peptide, reduces the extracellular population spike evoked by stimulation of stratum radiatum in area CA1 of the in vitro rat hippocampal slice, without reducing the antidromically evoked population spike. To test the hypothesis that NPY acts presynaptically, intracellular recordings were made of pyramidal neurones of area CA1 in vitro. 2. Bath application of 10(‐6) M‐NPY causes a long‐lasting (1‐1.5 h), reversible reduction of the orthodromically evoked excitatory post‐synaptic potential (e.p.s.p.) recorded intracellularly from CA1 pyramidal neurones. This effect on the e.p.s.p. was dependent upon the concentration of NPY. 3. The resting membrane potential, slope input resistance, and action potential threshold, amplitude and duration of the CA1 pyramidal neurones were not affected by NPY. 4. The responses of CA1 pyramidal neurones to ionophoretic pulses of glutamate, applied to the dendrites during synaptic blockade, was also unaffected by NPY. 5. The evidence supports the hypothesis that NPY acts presynaptically in the CA1 region of hippocampus to reduce excitatory input to the pyramidal neurones.
Effects of hypertonic solutions on calcium transients in frog twitch muscle fibres.
Authors: Parker I , Zhu P H
Published: December 2015

1. The effects of hypertonic solutions on excitation‐contraction (e.‐c.) coupling in frog skeletal muscle fibres were investigated using Arsenazo III to monitor intracellular calcium transients in voltage‐clamped fibres. 2. In solutions made hypertonic with sucrose or sodium chloride, the size of the Arsenazo signal evoked by a 5 ms depolarization to 0 mV was little altered by increases in tonicity up to about twice normal, but declined in higher tonicities, and was almost completely suppressed at 4 times normal tonicity. 3. The latency to onset of the Arsenazo signal was increased in hypertonic solutions (2.3 and 3.1 times normal tonicity), but the decay time constant of the signal was little changed with tonicities up to 2.3 times normal. 4. The rheobase potential for a just‐detectable Arsenazo signal was shifted about 4 mV more negative by increases in tonicity up to 2.3 times normal, but further increases reversed the direction of the shift, and in 3.95 times normal tonicity the rheobase was 10 mV more positive than in normal Ringer solution. 5. With short (less than 10 ms) pulse durations the depolarization needed to elicit a threshold Arsenazo signal increased steeply with increasing tonicity. Changes in the strength‐duration curve could be accounted for by an increase in the time constant for build‐up of a hypothetical coupler in the e.‐c. coupling process. 6. Solutions of about twice normal tonicity are commonly used to suppress muscle contraction. Since the size of the Arsenazo signal was only slightly reduced by this tonicity, the main effect is presumably on the contractile proteins.
The role of divalent cations in the N‐methyl‐D‐aspartate responses of mouse central neurones in culture.
Authors: Ascher P , Nowak L
Published: December 2015

1. Single‐channel currents activated by N‐methyl‐D‐aspartate (NMDA) agonists were analysed in the presence of various extracellular concentrations of divalent cations in outside‐out patches from mouse neurones in primary culture. 2. In nominally Mg2+‐free solutions the opening and closing of the channels leads to rectangular current pulses, the mean duration of which varies little with membrane potential. After addition of Mg2+, the single‐channel currents recorded at negative potentials appear in bursts of short openings separated by brief closures. 3. The duration of the short openings decreases with increasing Mg2+ concentration, while the duration of the short closures is independent of the Mg2+ concentration. Depolarization increases the duration of the short openings and decreases the duration of the short closures. 4. The dependence of the burst structure on the Mg2+ concentration and on membrane potential is compatible to a first approximation with a model in which Mg2+ ions enter the open channel and block it by binding at a deep site. A better approximation requires, however, additional assumptions such as Mg2+ permeation and/or interactions between Ca2+ and Mg2+. 5. Increasing the extracellular Ca2+ concentration from 1 to 100 mM produces three effects on the currents flowing through NMDA channels. It shifts the reversal potential towards a positive value (+30 mV); it reduces the outward current flowing through the NMDA channels at very positive potentials; it reduces the inward current flowing at negative potentials. 6. The interpretation of the effects of Ca2+ appears to require three hypotheses: that Ca2+ permeates the NMDA channel, that there exists a significant surface potential at the entrance of the NMDA channel in physiological solutions and that both Ca2+ and monovalent cations bind to the channel, binding being stronger in the case of Ca2+ ions. 7. While Co2+ and, to a lesser extent, Mn2+ mimic the effects of Mg2+ on the NMDA channel, Ca2+, Ba2+ and Cd2+ do not. The distinction between Mg2+‐like and Ca2+‐like divalent cations corresponds to a difference in the speed of exchange of the water molecules surrounding the cations in solutions. Thus, it is possible that permeation occurs for all the divalent cations, but is slower for those which are slowly dehydrated.
Frequency‐dependent N‐methyl‐D‐aspartate receptor‐mediated synaptic transmission in rat hippocampus.
Authors: Collingridge G L , Herron C E , Lester R A
Published: December 2015

1. The effects of the N‐methyl‐D‐aspartate (NMDA) antagonist, D‐2‐amino‐5‐phosphonovalerate (APV) were examined on synaptic responses evoked by high‐frequency stimulation of the Schaffer collateral‐commissural pathway, in the presence of Mg2+ (1 or 2 mM) and functional synaptic inhibition. 2. The synaptic response evoked by 100 Hz stimulation comprised fast excitatory postsynaptic potentials (EPSPs) evoked by each shock and a slow depolarization. APV reduced the size of the depolarization without depressing the fast EPSPs. 3. The mean (+/‐ 1 S.E.) amplitude of the APV‐sensitive component (3.0 +/‐ 0.3 mV), evoked by 100 Hz stimulation at membrane potentials near rest, was invariably smaller than the first fast EPSP (9.8 +/‐ 0.7 mV). Both of these synaptic components had similar thresholds and increased in amplitude as the stimulus intensity was raised. There was a positive correlation between the amplitude of the two components (r = 0.57, P less than 0.01). 4. The amplitude of the APV‐sensitive component was positively correlated (r = 0.97, P less than 0.05) with the frequency of stimulation during the trains (between 10 and 100 Hz). The threshold frequency for evoking an APV‐sensitive component was approximately 10 Hz. 5. In contrast to the fast EPSPs the amplitude of the APV‐sensitive component increased with depolarization, and decreased with hyperpolarization, of a neurone from its resting membrane potential. The component was no longer present in some cells which had been hyperpolarized sufficiently. 6. It is suggested that during high‐frequency stimulation a neurone may become depolarized for a sufficient time to reduce the Mg2+ block of NMDA channels. This enables the NMDA receptor system to contribute transiently to the synaptic response, despite the inhibitory synaptic mechanisms which prevent its activation during single‐shock stimulation. The characteristics of the NMDA receptor‐mediated synaptic response may explain properties relating to the induction of long‐term potentiation (LTP).
Lateral interactions at direction‐selective striate neurones in the cat demonstrated by local cortical inactivation.
Authors: Eysel U T , Muche T , Wörgötter F
Published: December 2015

1. Single neurones were recorded with glass‐coated tungsten electrodes from area 17 of the cat's visual cortex. The cats were anaesthetized and artificially respirated with a mixture of halothane, nitrous oxide and oxygen. 2. For local cortical inactivation a multibarrel pipette was placed 0.5‐2.5 mm posterior (or anterior) to the recording site, at a depth of 400‐600 micron. Four separate barrels of the pipette were filled with gamma‐aminobutyric acid (GABA); the fifth was filled with Pontamine Sky Blue for labelling of the centre of the inactivation site. 3. Direction‐selective cells, of differing optimal orientations and preferred directions of motion, were classified as simple or complex and tested with computer‐controlled stimuli presented on an oscilloscope. 4. During continuous recording GABA was microionophoretically applied for different durations and with different ejection currents. The effectiveness of GABA microionophoresis was evident from the direct GABAergic effects (strong overall inhibition of the recorded cells) observed with high ejection currents and prolonged application. 5. Two discrete effects could be observed during local inactivation distant from the cortical cell under study: an increase of the response in either the non‐preferred or the preferred direction; or a decrease of the response in the preferred direction. All GABA‐induced changes were reversible. 6. The depressant action of GABA was independent of the relative topography between recording and inactivation site and affected mainly the response to the preferred direction of stimulus motion. 7. Disinhibition was only observed when the stimulus‐evoked response moved on the cortical map in a direction from the GABA pipette towards the recording electrode. It is concluded that GABA reversibly silences inhibitory interneurones that are situated in the vicinity of the micropipette tip and are involved in generation of direction selectivity. 8. No fundamental differences between cells from different cortical layers were observed. The disinhibitory effects of GABA inactivation were more pronounced and more frequently seen in simple cells (61%) than in complex cells (38%), while the opposite was true for reduced excitation during lateral GABA inactivation (observed in 62% of the complex vs. 39% of the simple cells). Accordingly, lateral inhibition statistically prevails in simple cells and lateral excitation in complex cells. 9. Among the inhibitory and excitatory mechanisms affected by lateral GABA inactivation, inhibition is organized with a higher topographic specificity.(ABSTRACT TRUNCATED AT 400 WORDS)
Infrared Visualization of the Cavity Effect Using Origami-Inspired Surfaces
Authors: Blanc Mitchell J. , Mulford Rydge B. , Jones Matthew R. , Iverson Brian D.
Published: December 2015

Surface temperature and apparent radiative surface properties (emissivity, absorptivity) may be controlled by varying surface topology through a phenomenon known as the cavity effect. Cavities created by origami folds offer the potential to achieve dynamic control of apparent radiative surface properties through actuation. To illustrate this phenomenon, a thin (0.0254 mm) stainless-steel, specularly reflecting surface (emissivity, ε = 0.117) was resistively heated (6.74 W). Accordion-shaped folds (1.27 cm panels) were used to create V-shaped grooves that transition from 29° at the center to 180° near the edges. Thermocouples were attached to the center of each cavity panel (Figure (a)). An IR image of the surface (Figure (b)) reveals that the apparent temperature increases as the cavity angle decreases and is not necessarily indicative of the actual surface temperature. This increase is due to an increase in the number of specular reflections associated with the cavity effect. A similar folded surface was placed 7 cm from a blackbody radiator at 1000° C, to illustrate the change in apparent absorptivity with cavity angle. The cavity angle was held constant across the surface and varied between tests from 180° to 37° (Figure (c), top to bottom). The increase in apparent temperature is a direct result of the increase in apparent absorptivity for decreasing cavity angle, despite constant heating conditions.
Effects of High Frequency Droplet Train Impingement on Spreading-Splashing Transition, Film Hydrodynamics and Heat Transfer
Authors: Zhang Taolue , Alvarado Jorge , Muthusamy J. P. , Kanjirakat Anoop , Sadr Reza
Published: December 2015

The objective of this study is to investigate the effects of droplet-induced crown propagation regimes (spreading and splashing) on liquid film hydrodynamics and heat transfer. In this work, the effects of high frequency droplet train impingement on spreading-splashing transition, liquid film hydrodynamics and surface heat transfer were investigated experimentally. HFE-7100 droplet train was generated using a piezo-electric droplet generator at a fixed flow rate of 165 mL/h. Optical and IR images were captured at stable droplet impingement conditions to visualize the thermal physical process. The droplet-induced crown propagation transition phenomena from spreading to splashing were observed by increasing the droplet Weber number. The liquid film hydrodynamics induced by droplet train impingement becomes more complex when the surface was heated. Bubbles and micro-scale fingering phenomena were observed outside the impact crater under low heat flux conditions. Dry-out was observed outside the impact craters under high heat flux conditions. IR images of the heater surface show that heat transfer was most effective within the droplet impact crater zone due to high fluid inertia including high radial momentum caused by high-frequency droplet impingement. Time-averaged heat transfer measurements indicate that the heat flux-surface temperature curves are linear at low surface temperature and before the onset of dry-out. However, a sharp increase in surface temperature can be observed when dry-out appears on the heater surface. Results also show that strong splashing (We = 850) is unfavorable for heat transfer at high heat flux conditions due to instabilities of the liquid film, which lead to the onset of dry-out. In summary, the results show that droplet Weber number is a significant factor in the spreading-splashing transition, liquid film hydrodynamics and heat transfer.
Integrated Experimental and Analytical Wellbore Strengthening Solutions by Mud Plastering Effects
Authors: Salehi Saeed , Kiran Raj
Published: December 2015

Wellbore stability has plagued oil industry for decades. Inclusion of the mud in drilling and the effect of mud cake build up incorporate very complex chemical, thermal, mechanical, and physical phenomena. It is very difficult to quantify all these phenomena in one model. The after effects of mud cake buildup, its permeability and variation in thickness with time alter the actual stress profile of the formation. To see the impact of the whole mechanism, a combination of laboratory studies and numerical modeling is needed. This paper includes the procedure and results on stress profiles in near wellbore region based on laboratory studies of mud cake buildup in high pressure and high temperature environment using permeability plug apparatus (PPA). The damaged formation zone is very susceptible to drilling fluid and results in alteration of existing pore pressure and fracture pressure. This paper presents integrated experimental and analytical solutions for wellbore strengthening due to mud cake plastering. Conducting experiments on rock core disks has provided more realistic results which can resemble to field conditions. The experimental work here provides an insight to effect of mud cake build up at high pressure and high temperature conditions using a heterogeneous filtration medium prepared from different sandstone cores. Results were used in the analytical model to see the effect of stresses in the formation. The primary objective is to investigate the wellbore hoop stress changes due to formation of filter cake by mud plastering using the analytical models built upon the laboratory results. The models developed in this work provide insights to quantify on wellbore plastering effects by mud cake build up.
Reduction of Sulfur Dioxide Emissions by Burning Coal Blends
Authors: Rokni Emad , Panahi Aidin , Ren Xiaohan , Levendis Yiannis A.
Published: December 2015

Given that sulfur contents of coals vary widely, this work investigated whether cofiring of high-sulfur coals with low-sulfur coals of different ranks has any distinct advantages on lowering the sulfur dioxide emissions of the former coals, beyond those predicted based on their blending proportions. Such cofiring intends to take advantage of documented evidence in previous investigations at the author's laboratory, which demonstrated that lignite coals of low-sulfur, high-calcium, and high-sodium content undergo massive bulk fragmentation during their devolatilization. This particular behavior generates a large number of small-sized char particles which, upon effective dispersion in the gas, can heterogeneously absorb the emitted sulfur dioxide gases, i.e., act as defacto sorbents, and then retain them in the ash. This study included two high- and medium-sulfur bituminous coals, two low-sulfur lignite coals, and a sub-bituminous coal. Results showed that bituminous coals burning under substoichiometric (fuel-lean) conditions release most of their sulfur content in the form of SO2 gases, whereas low-ranked coals only partly release their sulfur as SO2. Furthermore, the SO2 emission from coal blends is nonlinear with blend proportions, hence, beneficial synergisms that result in substantial overall reductions of SO2 can be attained. Finally, NOx emissions from coal blends did not show consistent beneficial synergisms under the implemented fuel-lean combustion conditions.
Design of Nonperiodic Microarchitectured Materials That Achieve Graded Thermal Expansions
Authors: Hopkins Jonathan B. , Shaw Lucas A. , Weisgraber Todd H. , Farquar George R. , Harvey Chris D. , Spadaccini Christopher M.
Published: December 2015

The aim of this paper is to introduce an approach for optimally organizing a variety of nonrepeating compliant-mechanism-like unit cells within a large deformable lattice such that the bulk behavior of the lattice exhibits a desired graded change in thermal expansion while achieving a desired uniform stiffness over its geometry. Such lattices with nonrepeating unit cells, called nonperiodic microarchitectured materials, could be sandwiched between two materials with different thermal expansion coefficients to accommodate their different expansions and/or contractions induced by changing ambient temperatures. This capability would reduce system-level failures within robots, mechanisms, electronic modules, or other layered coatings or structures made of different materials with mismatched thermal expansion coefficients. The closed-form analytical equations are provided, which are necessary to rapidly calculate the bulk thermal expansion coefficient and Young's modulus of general multimaterial lattices that consist first of repeating unit cells of the same design (i.e., periodic microarchitectured materials). Then, these equations are utilized in an iterative way to generate different rows of repeating unit cells of the same design that are layered together to achieve nonperiodic microarchitectured material lattices such that their top and bottom rows achieve the same desired thermal expansion coefficients as the two materials between which the lattice is sandwiched. A matlab tool is used to generate images of the undeformed and deformed lattices to verify their behavior and an example is provided as a case study. The theory provided is also verified and validated using finite-element analysis (FEA) and experimentation.
A Four Degree of Freedom Robot for Positioning Ultrasound Imaging Catheters
Authors: Loschak Paul M. , Degirmenci Alperen , Tenzer Yaroslav , Tschabrunn Cory M. , Anter Elad , Howe Robert D.
Published: December 2015

In this paper, we present the design, fabrication, and testing of a robot for automatically positioning ultrasound (US) imaging catheters. Our system will point US catheters to provide real-time imaging of anatomical structures and working instruments during minimally invasive procedures. Manually navigating US catheters is difficult and requires extensive training in order to aim the US imager at desired targets. Therefore, a four-degree-of-freedom (4DOF) robotic system was developed to automatically navigate US imaging catheters for enhanced imaging. A rotational transmission enables 3DOF for pitch, yaw, and roll of the imager. This transmission is translated by the 4DOF. An accuracy analysis calculated the maximum allowable joint motion error. Rotational joints must be accurate to within 1.5 deg, and the translational joint must be accurate within 1.4 mm. Motion tests then validated the accuracy of the robot. The average resulting errors in positioning of the rotational joints were 0.04–0.22 deg. The average measured backlash was 0.18–0.86 deg. Measurements of average translational positioning and backlash errors were negligible. The resulting joint motion errors were well within the required specifications for accurate robot motion. The output of the catheter was then tested to verify the effectiveness of the handle motions to transmit torques and translations to the catheter tip. The catheter tip was navigated to desired target poses with average error 1.3 mm and 0.71 deg. Such effective manipulation of US imaging catheters will enable better visualization in various procedures ranging from cardiac arrhythmia treatment to tumor removal in urological cases.
Review of Flow-Excited Resonance of Acoustic Trapped Modes in Ducted Shallow Cavities
Authors: Aly Kareem , Ziada Samir
Published: December 2015

Flow-excited resonances of acoustic trapped modes in ducted shallow cavities are reviewed in this paper. The main components of the feedback mechanism which sustains the acoustic resonance are discussed with particular emphasis on the complexity of the trapped mode shapes and the strong three-dimensionality of the cavity flow oscillations during the resonance. Due to these complexities of the flow and sound fields, it is still difficult to theoretically or numerically model the interaction mechanism which sustains the acoustic resonance. Strouhal number and resonance amplitude charts are therefore included to help designers avoid the occurrence of resonance in new installations, and effective countermeasures are provided which can be implemented to suppress trapped mode resonances in operating plants.
Engineering tumors by rolling sheets
Authors: Wang Andrew Z.
Published: December 2015

Three-dimensional engineered tumors can recapitulate the hypoxic gradient of in vivo tumors.
Weakly Deleterious Mutations and Low Rates of Recombination Limit the Impact of Natural Selection on Bacterial Genomes
Authors: Price Morgan N. , Arkin Adam P.
Published: December 2015

Free-living bacteria are usually thought to have large effective population sizes, and so tiny selective differences can drive their evolution. However, because recombination is infrequent, “background selection” against slightly deleterious alleles should reduce the effective population size (

N
e

) by orders of magnitude. For example, for a well-mixed population with 10
12
individuals and a typical level of homologous recombination (
r
/
m
= 3, i.e., nucleotide changes due to recombination [
r
] occur at 3 times the mutation rate [
m
]), we predict that

N
e

is
<
10
7
. An argument for high

N
e

values for bacteria has been the high genetic diversity within many bacterial “species,” but this diversity may be due to population structure: diversity across subpopulations can be far higher than diversity within a subpopulation, which makes it difficult to estimate

N
e

correctly. Given an estimate of

N
e

, standard population genetics models imply that selection should be sufficient to drive evolution if

N
e

×
s
is >1, where
s
is the selection coefficient. We found that this remains approximately correct if background selection is occurring or when population structure is present. Overall, we predict that even for free-living bacteria with enormous populations, natural selection is only a significant force if
s
is above 10
−7
or so.

IMPORTANCE
Because bacteria form huge populations with trillions of individuals, the simplest theoretical prediction is that the better allele at a site would predominate even if its advantage was just 10
−9
per generation. In other words, virtually every nucleotide would be at the local optimum in most individuals. A more sophisticated theory considers that bacterial genomes have millions of sites each and selection events on these many sites could interfere with each other, so that only larger effects would be important. However, bacteria can exchange genetic material, and in principle, this exchange could eliminate the interference between the evolution of the sites. We used simulations to confirm that during multisite evolution with realistic levels of recombination, only larger effects are important. We propose that advantages of less than 10
−7
are effectively neutral.
Suppression of Drug Resistance in Dengue Virus
Authors: Mateo Roberto , Nagamine Claude M. , Kirkegaard Karla
Published: December 2015

Dengue virus is a major human pathogen responsible for 400 million infections yearly. As with other RNA viruses, daunting challenges to antiviral design exist due to the high error rates of RNA-dependent RNA synthesis. Indeed, treatment of dengue virus infection with a nucleoside analog resulted in the expected genetic selection of resistant viruses in tissue culture and in mice. However, when the function of the oligomeric core protein was inhibited, no detectable selection of drug resistance in tissue culture or in mice was detected, despite the presence of drug-resistant variants in the population. Suppressed selection of drug-resistant virus correlated with cooligomerization of the targeted drug-susceptible and drug-resistant core proteins. The concept of “dominant drug targets,” in which inhibition of oligomeric viral assemblages leads to the formation of drug-susceptible chimeras, can therefore be used to prevent the outgrowth of drug resistance during dengue virus infection.

IMPORTANCE
Drug resistance is a major hurdle in the development of effective antivirals, especially those directed at RNA viruses. We have found that one can use the concept of the genetic dominance of defective subunits to “turn cousins into enemies,” i.e., to thwart the outgrowth of drug-resistant viral genomes as soon as they are generated. This requires deliberate targeting of larger assemblages, which would otherwise rarely be considered by antiviral researchers.
Propionibacterium acnesas a cause of lung abscess in a cardiac transplant recipient
Authors: Veitch David , Abioye Abu , Morris-Jones Stephen , McGregor Alastair
Published: December 2015

A 29-year-old man was admitted with fevers, cough, left-sided chest pain and lethargy for 1 week. He had a cardiac transplant 10 years prior and was on immunosuppressive drugs. He was found to have a pulmonary lesion and went on to develop a lung abscess.Propionibacterium acneswas identified on matrix-assisted laser desorption ionisation mass spectrometry-time of flight and 16s rRNA gene sequencing after drainage. He was curatively treated with co-trimoxazole and co-amoxiclav. He divulged a longstanding history of seborrhoeic dermatitis with frequent flares leading to large volumes of squames collecting on his bed sheets. We hypothesise this was a possible route of entry: inhalation of thePropionibacterium. This case highlights how a common commensal bacterium,P. acnes, was able to cause pathology in an immunosuppressed patient. This is the only case of a patient with transplantation developing aP. acnespulmonary infection and the only case ofP. acnescausing these clinical features to be reported in the literature.
A rare cause of recurrent wheeze and seizures
Authors: Hassan Maryam , Quraeshi Saher , Zubairi Ali Bin Sarwar
Published: December 2015

A 34-year-old woman presented with recurrent attacks of breathlessness and seizures. The patient's condition worsened during the course of her hospital stay, as a result of which she had to be intubated twice. Radiological studies showed a mass in the trachea and the subsequent biopsy of the mass revealed an infiltrating carcinoma with morphological features of adenoid cystic carcinoma.
Protocol for an investigator-blinded, randomised, 3-month, parallel-group study to compare the efficacy of intraoperative tendon sheath irrigation only with both intraoperative and postoperative irrigation in the treatment of purulent flexor tenosynovitis
Authors: Leppänen Olli V , Jokihaara Jarkko , Kaivorinne Antti , Havulinna Jouni , Göransson Harry
Published: December 2015

Introduction

The management of purulent flexor tenosynovitis of the hand consists of surgical debridement followed by antibiotic treatment. Usually, the debridement is carried out by irrigating the tendon sheath in a proximal to distal direction facilitated by two small incisions. It is unclear whether intraoperative irrigation by itself is adequate for healing or if it should be combined with postoperative irrigation in the ward. The hypothesis of this prospective randomised trial is that intraoperative catheter irrigation alone is as effective as a combination of intraoperative and postoperative intermittent catheter irrigation in the treatment of purulent flexor tenosynovitis.

Methods and analysis

In this investigator-blinded, prospective randomised trial, 48 patients suffering from purulent flexor tenosynovitis are randomised in two groups. Intraoperative catheter irrigation of the flexor tendon sheath and antibiotic treatment is identical in both groups, whereas only the patients in one group are subjected to intermittent postoperative catheter irrigation three times a day for 3 days. The primary outcome measure is total active range of movement of the affected finger after 3 months of surgery. The secondary outcome is the need for reoperation.

Ethics and dissemination

The research ethics committee of Pirkanmaa Hospital District has approved the study protocol. The protocol has been registered with ClinicalTrials.gov registry (#NCT02320929). All participants will give written informed consent. The study results will elucidate the role of postoperative irrigation, which can be criticised as being labour consuming and unpleasant to the patient. The results of the study will be disseminated as a published article in a peer-reviewed journal.

Trial registration number:

NCT02320929; pre-results.
A feasibility study on the effects of Triton X-100 for the in vitro inactivation of Ebola virus on haematological assays
Authors: Mifsud Antoinette , Peelen Daphne , Brincat Patricia , Abela Sylvana , Debattista Neville , Laspina Stefan , Zammit Daniel , Camilleri David J , Gatt Alex
Published: December 2015

Aims

The aim of this study was to check the effect of Triton X-100 on various, commonly used haematology test parameters.

Methods

Anonymised blood samples were treated with 10 µL of 10% Triton X-100 per 1 mL of blood. Treated and untreated samples were tested in parallel for blood film morphology, complete blood counts (CBCs), flow cytometry, blood grouping and antibody screens. Samples were also taken in 3.2% citrate tubes for coagulation test analyses.

Results

Statistical differences were noted in all CBC parameters apart from the mean cell volume, eosinophil and basophil counts. Platelet counts were significantly different with an apparent rise after the addition of Triton X-100. Samples were noted to have a high red cell fragmentation index. Immunological platelet counting methods using flow cytometry and fluorescent methods showed no significant differences and gave reliable results. Neither flow cytometry for T-cell subsets nor blood grouping/antibody screens were affected by Triton X-100. However, coagulation samples were severely haemolysed prohibiting analysis.

Conclusions

We have demonstrated that the addition of Triton X-100 to haematology blood samples impacts mainly on platelet counts and coagulation studies due to haemolysis. The platelet count is spuriously raised probably due to the presence of red cell fragments. The latter can be circumvented by the use of immunological platelet counting technology.
Youth blogging and serious illness
Authors: Nesby Linda , Salamonsen Anita
Published: December 2015

In recent years, a growing number of young people who experience illness tend to blog about it. In this paper, we question whether and how illness blogs illustrate the intercommunicative aspect of blogging by bringing forth both the literary concept of the implied reader and the sociological concepts of empowerment and agency in the analysis. We argue that young people blogging about serious illness demonstrate the inherent intercommunicative potential of blogging. We also argue that youth blogging about serious illness may represent a fruitful strategy for ill young people to create meaning, stay front-stage in youth communities and build self-esteem and confidence out of chaos. Furthermore, we argue that these blogs may contribute rather unique experience-based knowledge and reflections about existential issues to other young blog readers, who may otherwise not get access to this aspect of life. Youth blogging about serious illness thereby reflects a patient group so far not very visible and through the genre youth stand out as more competent when it comes to illness and healthcare issues than what is often presumed.
Fish life history dynamics: shifts in prey size structure evoke shifts in predator maturation traits
Authors: Shuter Brian J. , Giacomini Henrique C. , de Kerckhove Derrick , Vascotto Kris
Published: December 2015

A bioenergetic framework is developed to predict optimal life history responses to environmentally driven changes in the rate of energy production by a predator. This framework is used to predict the responses of age at maturation, size at maturation, and asymptotic size to changes in the predator–prey size ratio. Predators feeding on relatively smaller prey (i.e., having larger predator–prey size ratios) have lower growth efficiency and are predicted as a consequence to mature earlier, at smaller sizes, and reach smaller asymptotic sizes. This prediction was tested using a 78-year time series (1936–2013) of data from a natural population of lake trout (Salvelinus namaycush) in Lake Opeongo, Algonquin Park, Ontario, Canada. A large decrease in the predator–prey size ratio for this population occurred over the period 1950–1965 when a preferred prey (cisco, Coregonus artedii) was introduced to the lake. This decrease was followed by ∼20 years of constancy in the size ratio and then 25 years of progressive increase. Lake trout life history responded plastically during both periods and consistently with our predictions. Extensive analysis of available data provided little empirical support for alternative explanations for the observed changes in lake trout size and maturity (e.g., changes in cisco and (or) lake trout density and harvest rates). The framework developed here derives plastic life history changes from fixed developmental thresholds that are based on the scaling of net production with body size and can be used to predict the shape of maturation reaction norms for the major shifts in community structure that are compactly summarized by changes in size spectrum parameters.
A stochastic mixed integer program to model spatial wildfire behavior and suppression placement decisions with uncertain weather
Authors: Belval Erin J. , Wei Yu , Bevers Michael
Published: December 2015

Wildfire behavior is a complex and stochastic phenomenon that can present unique tactical management challenges. This paper investigates a multistage stochastic mixed integer program with full recourse to model spatially explicit fire behavior and to select suppression locations for a wildland fire. Simplified suppression decisions take the form of “suppression nodes”, which are placed on a raster landscape for multiple decision stages. Weather scenarios are used to represent a distribution of probable changes in fire behavior in response to random weather changes, modeled using probabilistic weather trees. Multistage suppression decisions and fire behavior respond to these weather events and to each other. Nonanticipativity constraints ensure that suppression decisions account for uncertainty in weather forecasts. Test cases for this model provide examples of fire behavior interacting with suppression to achieve a minimum expected area impacted by fire and suppression.
Environmental persistence of Tulane virus — a surrogate for human norovirus
Authors: Arthur Sabastine Eugene , Gibson Kristen Elizabeth
Published: December 2015

Human noroviruses (HuNoVs) are the leading cause of acute viral gastroenteritis worldwide. The persistence of HuNoV in the environment contributes significantly to its transmission to humans. Surrogate viruses are used to study HuNoV owing to the lack of a cell culture system for this virus. Here, the persistence of Tulane virus (TV) — a novel HuNoV surrogate — in surface water (SW) and groundwater (GW) as well as on acrylic-based solid (ABS) and stainless steel (SS) surfaces was investigated. After 28 days, TV remained stable in SW (<1 log10 reduction) but was reduced by ≥3.5 to 4 log10 in GW by day 21. TV had a higher rate of reduction on SS compared with ABS, with corresponding D values of 18.5 ± 0.34 and 13.1 ± 0.36 days, respectively. This is the first study to demonstrate the persistence of TV in environmental waters and on fomite surfaces.
On the Riemann Problem Simulation for the Drift-Flux Equations of Two-Phase Flows
Authors: Kuila S. , Raja Sekhar T. , Zeidan D.
Published: December 2015

This work presents computational simulations and analytical techniques for solving the drift-flux two-phase flow model. The model equations are formulated to describe the exact solution of the Riemann problem. The solution is constructed by solving the conservation of mass for each phase and the mixture conservation momentum equation of the two phases under isothermal conditions. Particular attention is given to address the expressions for jump relationships and the Riemann invariants. The performance of the developed Riemann solver is assessed with respect to different test cases selected from the literature. Comparisons with Godunov methods of centred-type are provided to demonstrate the use of the proposed exact and computational framework. Excellent agreement is observed between analytical results and numerical predictions.
Local behaviors of the number of relatively prime sets
Authors: Pongsriiam Prapanpong
Published: December 2015

Let [Formula: see text] be the number of relatively prime subsets of [Formula: see text]. In this article, we obtain some local behaviors of [Formula: see text] and related functions. For instance, we show that [Formula: see text] is positive for every odd number [Formula: see text], and [Formula: see text] for every [Formula: see text].
Team Projects in Computing Education
Authors: Börstler Jürgen , Hilburn Thomas B.
Published: December 2015

Team projects are a way to expose students to conflicting project objectives, and “[t]here should be a strong real-world element … to ensure that the experience is realistic” [ACM/IEEE-CS 2015b]. Team projects provide students an opportunity to put their education into practice and prepare them for their professional careers. The aim of this special issue is to collect and share evidence about the state-of-practice of team projects in computing education and to help educators in designing and running team projects. From a record number of 69 submitted abstracts, 19 were invited to submit a full paper. Finally, nine papers were accepted for publication in this and a subsequent issue. The articles presented in the present issue cover the following topics: real projects for real clients, open source projects, multidisciplinary team projects, student and team assessment, and cognitive and psychological aspects of team projects.