bluuebunny/crossref_metadata_2025 huggingface dataset:
Predictive Large Eddy Simulation for Jet Aeroacoustics–Current Approach and Industrial Application
Authors: Tyacke James , Naqavi Iftekhar , Wang Zhong-Nan , Tucker Paul , Boehning Peer
Published: January 2017

The major techniques for measuring jet noise have significant drawbacks, especially when including engine installation effects such as jet–flap interaction noise. Numerical methods including low order correlations and Reynolds-averaged Navier–Stokes (RANS) are known to be deficient for complex configurations and even simple jet flows. Using high fidelity numerical methods such as large eddy simulation (LES) allows conditions to be carefully controlled and quantified. LES methods are more practical and affordable than experimental campaigns. The potential to use LES methods to predict noise, identify noise risks, and thus modify designs before an engine or aircraft is built is a possibility in the near future. This is particularly true for applications at lower Reynolds numbers such as jet noise of business jets and jet-flap interaction noise for under-wing engine installations. Hence, we introduce our current approaches to predicting jet noise reliably and contrast the cost of RANS–numerical-LES (RANS–NLES) with traditional methods. Our own predictions and existing literature are used to provide a current guide, encompassing numerical aspects, meshing, and acoustics processing. Other approaches are also briefly considered. We also tackle the crucial issues of how codes can be validated and verified for acoustics and how LES-based methods can be introduced into industry. We consider that hybrid RANS–(N)LES is now of use to industry and contrast costs, indicating the clear advantages of eddy resolving methods.
A Multi-User Computer-Aided Design Competition: Experimental Findings and Analysis of Team-Member Dynamics
Authors: Stone Brett , Salmon John , Eves Keenan , Killian Matthew , Wright Landon , Oldroyd Jordan , Gorrell Steve , Richey Michael C.
Published: January 2017

A competition for teams of three students using a prototype multi-user computer-aided design (MUCAD) tool was held to investigate various hypotheses regarding the performance of teams in such a setting. By comparing models from the competition to the same model in a single-user CAD environment, it is seen that use of a MUCAD system can significantly increase the value-added per unit of calendar time for a modeling effort. An investigation was also made into the causes of the performance differences among the various MUCAD teams which participated in the competition. Analysis of the results shows that teams that encouraged effective forms of communication and teams whose members scored similarly on the Purdue Spatial Visualization Test: Visualization of Rotations (PSVT:R) performed better than other teams. Areas of future research in analyzing teams in MUCAD environments are suggested.
Kinematically Redundant Planar Parallel Mechanisms for Optimal Singularity Avoidance
Authors: Isaksson Mats
Published: January 2017

A parallel mechanism possesses several advantages compared to a similar-sized serial mechanism, including the potential for higher accuracy and reduced moving mass, the latter enabling increased load capacity and higher acceleration. One of the most important issues affecting a parallel mechanism is the potential of parallel singularities. Such configurations strongly affect the performance of a parallel mechanism, both in the actual singularity and in its vicinity. For example, both the stiffness of a mechanism and the efficiency of the power transmission to the tool platform are related to the closeness to singular configurations. A mechanism with a mobility larger than the mobility of its tool platform is referred to as a kinematically redundant mechanism. It is well known that introducing kinematic redundancy enables a mechanism to avoid singular configurations. In this paper, three novel kinematically redundant planar parallel mechanisms are proposed. All three mechanisms provide planar translations of the tool platform in two degrees-of-freedom, in addition to infinite rotation of the platform around an axis normal to the plane of the translations. The unique feature of the proposed mechanisms is that, with the appropriate inverse kinematics solutions, all configurations in the entire workspace feature optimal singularity avoidance. It is demonstrated how it is sufficient to employ five actuators to achieve this purpose. In addition, it is shown how including more than five actuators significantly reduces the required actuator motions for identical motions of the tool platform, thereby reducing the cycle times for typical applications.
Probabilistic Failure of Graphite Epoxy Composite Plates Due to Low Velocity Impact
Authors: Patel Shivdayal , Ahmad Suhail
Published: January 2017

Stochastic finite-element analysis of composite plates due to low velocity impact (LVI) is studied, considering the material properties (Young's modulii, Poisson's ratio, strengths, and fracture energy) and initial velocity as random parameters. Damage initiation and propagation failure due to matrix cracking are investigated for safety criteria for the LVI. Progressive damage mechanics is employed to predict the stochastic dynamic response of the plates. The Gaussian process response surface method (GPRSM) is presently adopted to determine the probability of failure (Pf). There is a possibility of underestimation of the peak contact force and displacement by 10.7% and 11.03%, respectively, if the scatter in the properties is not considered. The sensitivity-based probabilistic design optimization procedure is investigated to achieve better strength and lighter weight of composite for body armors.
Innovative Design of an Automatic Acupoint Catgut-Embedding Instrument
Authors: Kuo Chin-Hsing , Wang Chun-Wen
Published: January 2017

Acupoint catgut-embedding (ACE) therapy is a type of acupuncture surgery that combines concepts of traditional Chinese medicine with modern medical instruments. The therapy involves using a hypodermic needle and an acupuncture needle to embed 1-cm long catgut segments in an acupoint, enabling the catgut to perform long-term stimulation of the acupoint and achieve the effects of acupuncture treatment. Each therapy process requires numerous repetitions of the same steps, and each needle set can only be used to embed one catgut segment. Additionally, doctors must perform this surgical procedure by hand; no automatic auxiliary instrument has been developed to date. To address these problems, this paper proposes an innovative design of the first automatic ACE auxiliary instrument in the world. The instrument could assist doctors to complete the ACE steps. And it neither requires a battery or external electric power nor changes needles during therapy. The study first involved designing the mechanism and embodiment for the instrument, enabling it to perform one catgut-embedding procedure in only two steps with the repeated use of one needle set. We then created the prototype and tested its functionality in terms of the success rate of catgut cutting, average length of catgut segments, the success rate of needle insertion and acupoint range, and the success rates of catgut insertion and catgut embedding. The results showed that the prototype did conform to our design goals, but the success rates of catgut cutting and catgut insertion could be further enhanced.
In-Calandria Retention of Corium in PHWR: Experimental Investigation and Remaining Issues
Authors: Prasad Sumit V. , Nayak A. K.
Published: January 2017

After the Fukushima accident, the public has expressed concern regarding the safety of nuclear power plants. This accident has strengthened the necessity for further improvement of safety in the design of existing and future nuclear power plants. Pressurized heavy water reactors (PHWRs) have a high level of defense-in-depth (DiD) philosophy to achieve the safety goal. It is necessary for designers to demonstrate the capability of decay heat removal and integrity of containment in a PHWR reactor for prolonged station blackout to avoid any release of radioactivity in public domain. As the design of PHWRs is distinct, its calandria vessel (CV) and vault cooling water offer passive heat sinks for such accident scenarios and submerged calandria vessel offers inherent in-calandria retention (ICR) features. Study shows that, in case of severe accident in PHWR, ICR is the only option to contain the corium inside the calandria vessel by cooling it from outside using the calandria vault water to avoid the release of radioactivity to public domain. There are critical issues on ICR of corium that have to be resolved for successful demonstration of ICR strategy and regulatory acceptance. This paper tries to investigate some of the critical issues of ICR of corium. The present study focuses on experimental investigation of the coolability of molten corium with and without simulated decay heat and thermal behavior of calandria vessel performed in scaled facilities of an Indian PHWR.
Nozzle Geometry Effect on Stratified Layer Erosion by Vertical Turbulent Jet
Authors: Ishay L. , Bieder U. , Ziskind G. , Rashkovan A.
Published: January 2017

Knowledge of the nuclear power plants (NPPs) containment atmosphere composition in the course of a severe accident is crucial for the effective design and positioning of the hydrogen explosion countermeasures. This composition strongly depends on containment flows which may include turbulent jet mixing in the presence of buoyancy, jet impingement onto the stratified layer, stable stratification layer erosion, steam condensation on the walls of the containment, condensation by emergency spray systems and other processes. Thus, in modeling of containment flows, it is essential to correctly predict these effects. In particular, a proper prediction of the turbulent jet behavior before it reaches the stably stratified layer is critical for the correct prediction of its mixing and impingement. Accordingly, validation study is presented for free neutral and buoyancy-affected turbulent jets, based on well-known experimental results from the literature. This study allows for the choice of a proper turbulence model to be applied for containment flow simulations. Furthermore, the jet behavior strongly depends on the issuing geometry. A comparative study of erosion process for the conditions similar to the ones of international benchmark exercise (IBE-3) is presented for different jet nozzle shapes.
Experimental and Numerical Study on Pressure Pulsations Under Various Acoustic Boundary Conditions in Piping Systems
Authors: Maekawa Akira , Tsuji Takashi , Noda Michiyasu , Takahashi Tsuneo , Kato Minoru , Fujita Katsuhisa
Published: January 2017

To improve design and troubleshooting techniques of piping systems for operating power plants, it is necessary to investigate, by experiment and simulation, the behavior of fluid inside the piping system in detail. This study was conducted using full-scale piping system under conditions that could seriously threaten the plant operation, by matching pressure pulsations, acoustic resonance, and piping natural frequency. Although piping vibration is reported to influence fluid pressure pulsations, there were no such examples of influence in this experiment. Knowing that the opening ratio of the pressure control valve affects the boundary condition for acoustic resonance, experiment and simulation at different opening ratios were conducted. It has been suggested that the cases in which a valve partially open at 25% or less should not be taken as a closed end. This finding conflicts with such a widespread design assumption.
Computational Fluid Dynamics Simulations of Convective Pure Vapor Condensation Inside Vertical Cylindrical Condensers
Authors: Cao Huali , Li Jun-De
Published: January 2017

This paper presents the results from computational fluid dynamics (CFD) simulations of heat and mass transfer of pure vapor flowing and condensing in a vertical cylindrical condenser system at various inlet temperatures, mass flow rates, and operating pressure for the case where the vapor condensation is not completed inside the condenser tube. The heat and mass transfer inside the condenser tube is simulated as single phase flow, and the thin condensate film on the condensing surface is replaced by a set of boundary conditions that couple the CFD simulations inside the condenser tube and the coolant channel. The CFD results are compared with the experimental results, and good agreement has been found for the various measured temperatures. It is found that both the wall temperature and the heat flux vary significantly along the condenser tube, and it is necessary to consider the conjugate problem that consists of the whole condenser system (condenser plus coolant flow) in predicting the pure vapor condensation in a condensing system. The CFD results show that the heat flux along the condenser tube can be increasing for counter-flow condenser, and the condensate film may not be the main limiting factor in the pure vapor condensation. The results from the CFD simulations also show that the estimation of the interface shear stress cannot be based on the bulk velocity of the water vapor alone.
Definition and Implementation of a Method for Uncertainty Aggregation in Component-Based System Simulation Models
Authors: Eek Magnus , Gavel Hampus , Ölvander Johan
Published: January 2017

Component-based system simulation models are used throughout all development phases for design and verification of both physical systems and control software, not least in the aeronautical industry. However, the application of structured methods for uncertainty quantification (UQ) of system simulation models is rarely seen. To enable dimensionality reduction of a UQ problem and to thereby make UQ more feasible for industry-grade system simulation models, this paper describes a pragmatic method for uncertainty aggregation. The central idea of the proposed aggregation method is to integrate information obtained during common practice component-level validation directly into the components, and to utilize this information in model-level UQ. A generic component output uncertainty description has been defined and implemented in a Modelica library for modeling and simulation (M&S) of aircraft vehicle systems. An example is provided on how to characterize and quantify a component's aggregated output uncertainty based on the component-level bench test measurement data. Furthermore, the industrial applicability of the uncertainty aggregation method is demonstrated in an approximate UQ of an aircraft liquid cooling system simulation model. For cases when the concept of thorough UQ resulting in probability boxes is not feasible, the demonstrated approximate UQ using aggregated uncertainties is considered to be a pragmatic alternative fairly in reach for the common M&S practitioner within the area of system simulation.
Experimental Study of a Solar Air Heater With a New Arrangement of Transverse Longitudinal Baffles
Authors: Mahmood Afaq Jasim
Published: January 2017

This study presents a new design for improving the convection heat transfer coefficients of double-pass solar air heater. Three cases were described by using a different number of transverse baffles (three, five, and seven) in the lower channel of the collectors; steel mesh sheets were also used to enlarge the heat transfer area. All collectors have a space of 25 mm between its glass covers and a 50 mm depth of air channel. Furthermore, this work examined the effect of air flow rate and baffles number on device's thermal efficiency and outlet temperature. The experimental results indicate raises in the thermal efficiency as the air flow rate goes from 0.011 kg/s to 0.038 kg/s. A maximum efficiency of 68% was obtained from the case of seven baffles at the air flow rate of 0.038 kg/s. Moreover, the difference between collector's inlet and outlet temperatures, ΔT, indicated an inverse relationship with air flow rate. Thus, the results show ΔT increases as the air flow rate reduced. The maximum temperature difference recorded was 54 °C, which achieved using seven baffled solar air heater at 0.011 kg/s air flow rate in the middle of the day. It has also been found that thermal efficiency of double-pass solar air heater is greater than single-pass solar air heater, using same air flow rate and number of baffles. Finally, the pressure drop associated with increasing the number of baffles and air flow rate was deliberated.
Nonholonomic Formulation of Ab Initio Molecular Dynamics
Authors: Fahrenthold Eric P.
Published: January 2017

A new nonholonmic Hamiltonian formulation of ab initio molecular dynamics extends current Ehrenfest, Car–Parrinello, and Born–Oppenheimer formulations, offering potential improvements to modeling methods employed in computational materials design.
Image-Based Slicing and Tool Path Planning for Hybrid Stereolithography Additive Manufacturing
Authors: Ye Hang , Zhou Chi , Xu Wenyao
Published: January 2017

The hybrid stereolithography (SLA) process integrates a laser scanning-based system and a mask projection-based system. Multiple laser paths are used to scan the border of a 2D pattern, whereas a mask image is adopted to solidify the interior area. By integrating merits of two subsystems, the hybrid SLA process can achieve high surface quality without sacrificing productivity. For the hybrid system, closed polygonal contours are required to direct the laser scanning, and a binary image is also needed for the mask projection. We proposed a novel image-based slicing method. This approach can convert a 3D model into a series of binary images directly, and each image is corresponding to the cross section of the model at a specific height. Based on the resultant binary image, we use an image processing method to gradually shrink the pattern in the image. Boundaries of the shrunk image are traced and then restored as polygons to direct the laser spot movement. The final shrunk image serves as the input for the mask projection. Experimental results of test cases demonstrate that the proposed method is substantially more efficient than the traditional approaches. Its accuracy is also studied and discussed.
Impacts of Discretization Error, Flow Modeling Error, and Measurement Noise on Inverse Transport-Diffusion-Reaction in a T-Junction
Authors: Waeytens Julien , Chatellier Patrice , Bourquin Frédéric
Published: January 2017

By combining a physical model and sensor outputs in an inverse transport-diffusion-reaction strategy, an accurate concentration cartography may be obtained. The paper addresses the influence of discretization errors, flow uncertainties, and measurement noise on the concentration field reconstruction process. We consider a key element of a drinking water network, i.e., a pipe junction, where Reynolds and Peclet numbers are approximately 2000 and 1000, respectively. We show that a 10% error between the reference concentration field and the reconstructed concentration field may be obtained using a coarse discretization. Nevertheless, to keep the error below 10%, a fine concentration discretization is required. We also detail the influence of the flow approximation on the concentration reconstruction process. The flow modeling error obtained when the exact Navier–Stokes flow is approximated by a Stokes flow may lead to a 40% error in the reconstructed concentration. However, if the flow field is obtained from the full set of Navier–Stokes equations, we show that the error may be less than 5%. Then, we observe that the quality of the reconstructed concentration field obtained with the proposed inverse technique is not deteriorated when sensor outputs have a normal distribution noise variance of few percents. Finally, a good engineering practice would be to stop the reconstruction process according to an extended discrepancy principle including modeling and measurement errors. As shown in the paper, the quality of the reconstructed field declines after reaching the threshold of the modeling error.
Nonsynchronous Vibration of Planar Autobalancer/Rotor System With Asymmetric Bearing Support
Authors: Jung DaeYi , DeSmidt Hans
Published: January 2017

Due to inherent nonlinearity of the autobalancer, the potential for other, undesirable, nonsynchronous limit-cycle vibration exists. In such undesirable situations, the balancer masses do not reach their desired synchronous balanced steady-state positions resulting in increased rotor vibration. Such behavior has been widely studied and is well understood for rotor systems on idealized bearings with symmetric supports. However, a comprehensive study into this nonlinear behavior of an imbalanced planar-rigid rotor/autobalancing device (ABD) system mounted on a general bearing holding asymmetric damping and stiffness forces including nonconservative effects cross-coupling ones has not been fully conducted. Therefore, this research primarily focuses on the unstable nonsynchronous limit-cycle behavior and the synchronous balancing condition of system under the influence of the general bearing support. Here, solutions for rotor limit-cycle amplitudes and the corresponding whirl speeds are obtained via a harmonic balance approach. Furthermore, the limit-cycle stability is assessed via perturbation and Floquet analysis, and all the possible responses including undesirable coexistence for the bearing parameters and operating speeds have been thoroughly studied. It is found that, due to asymmetric behavior of bearing support, the multiple limit cycles are encountered in the range of supercritical speeds and more complicate coexistences are invited into the ABD–rotor system compared to the case with idealized symmetric bearing supports. The findings in this paper yield important insights for researchers wishing to utilize automatic balancing devices in more practical rotor systems mounted on a asymmetric general bearing support.
Sliding down an arbitrary curve in the presence of friction
Authors: González-Cataldo Felipe , Gutiérrez Gonzalo , Yáñez Julio M.
Published: January 2017

The motion of a block sliding on a curve is a well studied problem for flat and circular surfaces, but the necessary conditions for the block to leave the surface deserve a deeper treatment. In this article, we generalize this problem to an arbitrary surface, including the effects of friction, and provide a general expression to determine under what conditions a particle will leave the surface. An explicit integral form for the speed is given, which is analytically integrable for some cases. We demonstrate general criteria to determine the critical speed at which the particle immediately leaves the surface. Three curves, a circle, a cycloid, and a catenary, are analyzed in detail, revealing several interesting features.
The motion of a ball moving down a circular path
Authors: de Souza Diego C. , Coluci Vitor R.
Published: January 2017

The problem of a body slipping down a frictionless hemisphere is very common in physics and engineering textbooks. In this type of problem, students are normally asked to find the angle at which the body flies off the surface. In this work, we have constructed an apparatus to determine the angle at which a ball flies off a circular track, and to study the motion of the ball (rolling and slipping) along the surface. The apparatus is comprised of two parallel rails that form a quarter circle. The angular position and velocity of a steel ball are measured using a moveable arm equipped with a photodetector. Two methods are used to determine the angle the ball loses contact with the track. Both methods provide values in agreement with a model for rolling followed by slipping.
The polio endgame: rationale behind the change in immunisation
Authors: Garon Julie , Patel Manish
Published: January 2017

The decades long effort to eradicate polio is nearing the final stages and oral polio vaccine (OPV) is much to thank for this success. As cases of wild poliovirus continue to dwindle, cases of paralysis associated with OPV itself have become a concern. As type-2 poliovirus (one of three) has been certified eradicated and a large proportion of OPV-related paralysis is caused by the type-2 component of OPV, the World Health Assembly endorsed the phased withdrawal of OPV and the introduction of inactivated polio vaccine (IPV) into routine immunisation schedules as a crucial step in the polio endgame plan. The rapid pace of IPV scale-up and uptake required adequate supply, planning, advocacy, training and operational readiness. Similarly, the synchronised switch from trivalent OPV (all three types) to bivalent OPV (types 1 and 3) involved an unprecedented level of global coordination and country commitment. The important shift in vaccination policy seen through global IPV introduction and OPV withdrawal represents an historical milestone reached in the polio eradication effort.
Extended objects in nonperturbative quantum-field theory and the cosmological constant
Authors: Dzhunushaliev Vladimir , Folomeev Vladimir , Kleihaus Burkhard , Kunz Jutta
Published: January 2017

We consider a gravitating extended object constructed from vacuum fluctuations of nonperturbatively quantized non-Abelian gauge fields. An approximate description of such an object is given by two gravitating scalar fields. The object has a core filled with a constant energy density of the vacuum fluctuations of the quantum-fields. The core is located inside a cosmological event horizon. An exact analytical solution of the Einstein equations for such a core is presented. The value of the energy density of the vacuum fluctuations is connected with the cosmological constant.
Bandwidth Price Estimation for Scalable and Responsive Rate Control
Authors: ABBAS GHULAM
Published: January 2017

This paper concerns the analysis of important algorithmic attributes, namely, the rate of convergence and scalability, and their impact on Network Utility Maximization (NUM). The contribution of the paper is a novel distributed rate control mechanism with strong convergence and scalability properties. The proposed algorithm employs a distinctive distributed framework, where rate control is derived as a Sequential Quadratic Programming (SQP) mechanism incorporated with interior-point and trust-region methods. The NUM problem is solved by a barrier method that penalizes any violation of constraints. Lagrangian is applied to the barrier objective function, where multipliers are estimated using Least-square method to iteratively solve the quadratic approximation of the Lagrangian function at the current point to generate a search direction. The uniqueness of the algorithm is that it allows sources to estimate bandwidth prices and thereby enforces a scalable network core by pushing algorithmic complexity to the edges. The fast convergence of the algorithm, in turn, improves the responsiveness of rate control and enables reduced buffer occupancy. The convergence of the proposed algorithm is proved theoretically and is evaluated via simulations. The results demonstrate reasonable reduction of computation-time in tracking the optimal rates and validate the strong convergence properties of the proposed algorithm.
Embedding Every Cycle in Conditionally Faulty Folded Hypercubes
Authors: KUO CHE-NAN
Published: January 2017

A network is said to be conditionally faulty if its every vertex is incident to at least g fault-free neighbors, where g≥1. An n-dimensional folded hypercube FQn is a well-known variation of an n-dimensional hypercube Qn, which can be constructed from Qn by adding an edge to every pair of vertices with complementary addresses. In this paper, we define that a network is said to be g-conditionally faulty if its every vertex is incident to at least g fault-free neighbors, and let FFv (respectively, FFe) denote the set of faulty vertices (respectively, faulty edges) in FQn. Then, we consider for the cycles embedding properties in FQn−FFv−FFe with 4-conditionally faulty, as follows:

(1) For n≥3, FQn−FFv−FFe contains a fault-free cycle of every even length from 4 to 2n−2|FFv|, where |FFn|+|FFe| ≤ 2n−5;

(2) For even n≥4, FQn−FFv−FFe contains a fault-free cycle of every odd length from n+1 to 2n−2|FFv|−1, where |FFv|+|FFe| ≤ 2n−5.
Global well-posedness for the 3D viscous nonhomogeneous incompressible magnetohydrodynamic equations
Authors: Zhai Xiaoping , Li Yongsheng , Yan Wei
Published: January 2017

In this paper, we investigate the Cauchy problem for the 3D viscous nonhomogeneous incompressible magnetohydrodynamic equations in critical Besov spaces. We aim at proving the local and global well-posedness for respectively large and small initial data having critical Besov regularity, without assumptions of small density variation.
Continuous and discrete frames generated by the evolution flow of the Schrödinger equation
Authors: Alberti Giovanni S. , Dahlke Stephan , De Mari Filippo , De Vito Ernesto , Vigogna Stefano
Published: January 2017

We study a family of coherent states, called Schrödingerlets, both in the continuous and discrete setting. They are defined in terms of the Schrödinger equation of a free quantum particle and some of its invariant transformations.
Smart machines are not a threat to humanity
Authors: Bundy Alan
Published: January 2017

Worrying about machines that are too smart distracts us from the real and present threat from machines that are too dumb.
Life beyond distributed transactions
Authors: Helland Pat
Published: January 2017

An apostate's opinion.
Liberal arts academia wants YOU!
Authors: Davis Janet
Published: January 2017

The
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Communications
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Janet Davis makes a plea to CS practitioners to consider even a short teaching stint.
Are you load balancing wrong?
Authors: Limoncelli Thomas A.
Published: January 2017

Anyone can use a load balancer. Using it properly is much more difficult.
SIGCSE symposium 2017 preview
Authors: Edwards Stephen H. , Caspersen Michael E.
Published: January 2017

We invite everyone to join us in Seattle, Washington, for the 48th ACM Technical Symposium on Computer Science Education, March 8-11, 2017. The Symposium will address problems common among educators working to develop, implement and/or evaluate computing programs, curricula, and courses. It provides a forum for sharing new ideas for syllabi, laboratories, and other elements of teaching and pedagogy, at all levels of instruction.
ITiCSE 2017 preview
Authors: Davoli Renzo , Goldweber Michael
Published: January 2017

The 22nd Annual Conference on Innovation and Technology in Computer Science Education (ITiCSE 2017) is returning to Bologna, Italy. The program of the conference will consist of keynote lectures, paper sessions, panels, working groups, tips and techniques, courseware demonstrations, and posters.
Member spotlight
Authors: Doyle Maureen
Published: January 2017

In this feature of the Bulletin, we highlight members of the SIGCSE community. In this issue, Bulletin co-editor Maureen Doyle interviewed Alison Clear, Associate Professor of Computing at Eastern Institute of Technology in Auckland, New Zealand. Alison recently completed her term on the SIGCSE Board.
Migration and Dialect Contact
Authors: Dodsworth Robin
Published: January 2017

A great deal of research during the past 40 years and earlier investigates the outcomes of large-scale contact between mutually intelligible dialects. In the context of well-established types of dialect convergence, this article summarizes research from the past 10 years on migration-induced dialect contact. I devote particular attention to ongoing dialect contact in the urban settings of London, England; São Paulo, Brazil; Xining, China; Amman, Jordan; and New York City, United States. In all cases, the data show evidence of the expected process of dialect leveling, but linguistic innovations emerging from dialect contact are also prominent. Social network and identity factors are predicted to define much future dialect contact research.
Inability to replete white adipose tissue during recovery phase of sepsis is associated with increased autophagy, apoptosis, and proteasome activity
Authors: Crowell Kristen T. , Soybel David I. , Lang Charles H.
Published: January 2017

Adipose tissue is an important energy depot and endocrine organ, and the degree of adiposity impacts the host response to infection. However, little is known regarding the mechanisms by which white adipose tissue (WAT) is lost acutely and then restored after the resolution of sepsis. Therefore, the signaling pathways governing protein synthesis, autophagy, apoptosis, and the ubiquitin-proteasome were investigated to identify potential mechanisms mediating the acute (24 h) loss of WAT after cecal ligation and puncture as well as the failure to replenish WAT during recovery ( day 10). While whole body fat mass was decreased equally in pair-fed control and septic mice at 5 days after cecal ligation and puncture, fat mass remained 35% lower in septic mice at day 10. During sepsis-recovery, protein synthesis in epididymal WAT was increased compared with control values, and this increase was associated with an elevation in eukaryotic translation initiation factor (eIF)2Bε but no change in mammalian target of rapamycin complex 1 activity (eIF4E-binding protein-1 or S6 kinase 1 phosphorylation). Protein breakdown was increased during sepsis-recovery, as evidenced by the elevation in ubiquitin-proteasome activity. Moreover, indexes of autophagy (light chain 3B-II, autophagy-related protein 5/12, and beclin) were increased during sepsis-recovery and associated with increased AMP-activated kinase-dependent Ser555-phosphorylated Unc-51-like autophagy activating kinase-1. Apoptosis was increased, as suggested by the increased cleavage of caspase-3 and poly(ADP-ribose) polymerase. These changes were associated with increased inflammasome activity (increased NLR family, pyrin domain containing 3; TMS1; and caspase-1 cleavage) and the endoplasmic reticulum stress response (increased eIF2α and activating transcription factor-4) and browning (uncoupling protein-1) in epididymal WAT. Our data suggest that WAT stores remain depleted during recovery from sepsis due to sustained inflammation and elevations in protein and cellular degradation, despite the increase in protein synthesis.
Gremlin1 plays a key role in kidney development and renal fibrosis
Authors: Church Rachel H. , Ali Imran , Tate Mitchel , Lavin Deborah , Krishnakumar Arjun , Kok Helena M. , Hombrebueno Jose R. , Dunne Philip D. , Bingham Victoria , Goldschmeding Roel , Martin Finian , Brazil Derek P.
Published: January 2017

Gremlin1 (Grem1), an antagonist of bone morphogenetic proteins, plays a key role in embryogenesis. A highly specific temporospatial gradient of Grem1 and bone morphogenetic protein signaling is critical to normal lung, kidney, and limb development. Grem1 levels are increased in renal fibrotic conditions, including acute kidney injury, diabetic nephropathy, chronic allograft nephropathy, and immune glomerulonephritis. We demonstrate that a small number of grem1−/− whole body knockout mice on a mixed genetic background (8%) are viable, with a single, enlarged left kidney and grossly normal histology. The grem1−/− mice displayed mild renal dysfunction at 4 wk, which recovered by 16 wk. Tubular epithelial cell-specific targeted deletion of Grem1 ( TEC-grem1-cKO) mice displayed a milder response in the acute injury and recovery phases of the folic acid model. Increases in indexes of kidney damage were smaller in TEC-grem1-cKO than wild-type mice. In the recovery phase of the folic acid model, associated with renal fibrosis, TEC-grem1-cKO mice displayed reduced histological damage and an attenuated fibrotic gene response compared with wild-type controls. Together, these data demonstrate that Grem1 expression in the tubular epithelial compartment plays a significant role in the fibrotic response to renal injury in vivo.
Furosemide depresses the presynaptic fiber volley and modifies frequency-dependent axonal excitability in rat hippocampus
Authors: Andreasen Mogens , Nedergaard Steen
Published: January 2017

The loop diuretic furosemide is known to have anticonvulsant effects, believed to be exerted through blockade of glial Na+-K+-2Cl− cotransport causing altered volume regulation in brain tissue. The possibility that direct effects of furosemide on neuronal properties could also be involved is supported by previous observations, but such effects have not been thoroughly investigated. In the present study we show that furosemide has two opposing effects on stimulus-induced postsynaptic excitation in the nonepileptic rat hippocampal slice: 1) an enhancement of e-s coupling, which depended on intact GABAA transmission and was partially mimicked by selective blockade of K+-2Cl− cotransport, and 2) a decrement of field excitatory postsynaptic potentials. The balance between these effects varied, depending on the amount of synaptic drive. In addition, the compound action potential (fiber volley) recorded from the stimulated Schaffer collateral axons in stratum radiatum showed a progressive decrease during perfusion of furosemide. This effect was activity-independent, was mimicked by the stilbene derivative DIDS, and could be reproduced on fiber volleys in the alveus. Furosemide also reduced the initial enhancement of the fiber volley observed during trains of high-frequency stimulation (HFS). Results of hyperosmotic expansion of the extracellular volume, with 30 mM sucrose, indicated that both the induction and antagonism of the HFS-induced enhancement were independent of signaling via the extracellular space. Furosemide caused an increased decay of paired-pulse-induced supranormal axonal excitability, which was antagonized by ZD7288. We conclude that furosemide decreases axonal excitability and prevents HFS-induced hyperexcitability via mechanisms downstream of blockage of anion transport, which could include hyperpolarization of axonal membranes.

NEW & NOTEWORTHY This study shows that the anion transporter antagonists furosemide and DIDS cause a marked decrease of axonal excitability in rat hippocampal CA1 region and prevent the induction of activity-dependent hyperexcitability in Schaffer collateral axons. The data are consistent with direct effects on axonal membrane properties. We also find that activity-dependent enhancement and depression of axonal excitability can be modified independently, suggesting that these events are governed by different underlying processes.
Frequency tuning of synaptic inhibition underlying duration-tuned neurons in the mammalian inferior colliculus
Authors: Valdizón-Rodríguez Roberto , Faure Paul A.
Published: January 2017

Inhibition plays an important role in creating the temporal response properties of duration-tuned neurons (DTNs) in the mammalian inferior colliculus (IC). Neurophysiological and computational studies indicate that duration selectivity in the IC is created through the convergence of excitatory and inhibitory synaptic inputs offset in time. We used paired-tone stimulation and extracellular recording to measure the frequency tuning of the inhibition acting on DTNs in the IC of the big brown bat ( Eptesicus fuscus). We stimulated DTNs with pairs of tones differing in duration, onset time, and frequency. The onset time of a short, best-duration (BD), probe tone set to the best excitatory frequency (BEF) was varied relative to the onset of a longer-duration, nonexcitatory (NE) tone whose frequency was varied. When the NE tone frequency was near or within the cell’s excitatory bandwidth (eBW), BD tone-evoked spikes were suppressed by an onset-evoked inhibition. The onset of the spike suppression was independent of stimulus frequency, but both the offset and duration of the suppression decreased as the NE tone frequency departed from the BEF. We measured the inhibitory frequency response area, best inhibitory frequency (BIF), and inhibitory bandwidth (iBW) of each cell. We found that the BIF closely matched the BEF, but the iBW was broader and usually overlapped the eBW measured from the same cell. These data suggest that temporal selectivity of midbrain DTNs is created and preserved by having cells receive an onset-evoked, constant-latency, broadband inhibition that largely overlaps the cell’s excitatory receptive field. We conclude by discussing possible neural sources of the inhibition.

NEW & NOTEWORTHY Duration-tuned neurons (DTNs) arise from temporally offset excitatory and inhibitory synaptic inputs. We used single-unit recording and paired-tone stimulation to measure the spectral tuning of the inhibitory inputs to DTNs. The onset of inhibition was independent of stimulus frequency; the offset and duration of inhibition systematically decreased as the stimulus departed from the cell’s best excitatory frequency. Best inhibitory frequencies matched best excitatory frequencies; however, inhibitory bandwidths were more broadly tuned than excitatory bandwidths.
Maps of cone opsin input to mouse V1 and higher visual areas
Authors: Rhim Issac , Coello-Reyes Gabriela , Ko Hee-Kyoung , Nauhaus Ian
Published: January 2017

Studies in the mouse retina have characterized the spatial distribution of an anisotropic ganglion cell and photoreceptor mosaic, which provides a solid foundation to study how the cortex pools from afferent parallel color channels. In particular, the mouse’s retinal mosaic exhibits a gradient of wavelength sensitivity along its dorsoventral axis. Cones at the ventral extreme mainly express S opsin, which is sensitive to ultraviolet (UV) wavelengths. Then, moving toward the retina’s dorsal extreme, there is a transition to M-opsin dominance. Here, we tested the hypothesis that the retina’s opsin gradient is recapitulated in cortical visual areas as a functional map of wavelength sensitivity. We first identified visual areas in each mouse by mapping retinotopy with intrinsic signal imaging (ISI). Next, we measured ISI responses to stimuli along different directions of the S- and M-color plane to quantify the magnitude of S and M input to each location of the retinotopic maps in five visual cortical areas (V1, AL, LM, PM, and RL). The results illustrate a significant change in the S:M-opsin input ratio along the axis of vertical retinotopy that is consistent with the gradient along the dorsoventral axis of the retina. In particular, V1 populations encoding the upper visual field responded to S-opsin contrast with 6.1-fold greater amplitude than to M-opsin contrast. V1 neurons encoding lower fields responded with 4.6-fold greater amplitude to M- than S-opsin contrast. The maps in V1 and higher visual areas (HVAs) underscore the significance of a wavelength sensitivity gradient for guiding the mouse’s behavior.

NEW & NOTEWORTHY Two elements of this study are particularly novel. For one, it is the first to quantify cone inputs to mouse visual cortex; we have measured cone input in five visual areas. Next, it is the first study to identify a feature map in the mouse visual cortex that is based on well-characterized anisotropy of cones in the retina; we have identified maps of opsin selectivity in five visual areas.
Asymptotics for the Ostrovsky-Hunter Equation in the Critical Case
Authors: Bernal-Vílchis Fernando , Hayashi Nakao , Naumkin Pavel I.
Published: January 2017

We consider the Cauchy problem for the Ostrovsky-Hunter equation ∂x∂tu-b/3∂x3u-∂xKu3=au, t,x∈R2,  u0,x=u0x, x∈R, where ab>0. Define ξ0=27a/b1/4. Suppose that K is a pseudodifferential operator with a symbol K^ξ such that K^±ξ0=0, Im K^ξ=0, and K^ξ≤C. For example, we can take K^ξ=ξ2-ξ02/ξ2+1. We prove the global in time existence and the large time asymptotic behavior of solutions.
Percutaneous Vertebroplasty Relieves Pain in Cervical Spine Metastases
Authors: Bao Li , Jia Pu , Li Jinjun , Chen Hao , Dong Yipeng , Feng Fei , Yang He , Chen Mengmeng , Tang Hai
Published: January 2017

Percutaneous vertebroplasty (PVP) has been shown to release spinal pain and stabilize the vertebral body. PVP is suggested as an alternative treatment in spinal metastasis. Although cervical metastases is less prevalent than thoracic and lumbar spine, PVP procedure in cervical vertebrae remains technical challenging. We retrospectively analyzed the data from patients (n=9) who underwent PVP using anterolateral approach to treat severe neck pain and restricted cervical mobility from metastatic disease. Patients were rated using modified Tokuhashi score and Tomita score before the procedure. Visual analog scale (VAS), neck disability index (NDI), analgesic use, and imaging (X-ray or CT) were evaluated before PVP and 3 days, 3 months, and 6 months after PVP. All patients were in late stage of cancer evaluated using modified Tokuhashi and Tomita score. The cement leakage rate was 63.6% (14 of the 22 vertebrae) with no severe complications. VAS, NDI, and analgesic use were significantly decreased 3 days after the procedure and remained at low level until 6 months of follow-up. Our result suggested PVP effectively released the pain from patients with cervical metastasis. The results warrant further clinical investigation.
Predictive Factors for a Long Hospital Stay in Patients Undergoing Laparoscopic Cholecystectomy
Authors: Ko-iam Wasana , Sandhu Trichak , Paiboonworachat Sahattaya , Pongchairerks Paisal , Chotirosniramit Anon , Chotirosniramit Narain , Chandacham Kamtone , Jirapongcharoenlap Tidarat , Junrungsee Sunhawit
Published: January 2017

Background. Although the advantages of laparoscopic cholecystectomy (LC) over open cholecystectomy are immediately obvious and appreciated, several patients need a postoperative hospital stay of more than 24 hours. Thus, the predictive factors for this longer stay need to be investigated. The aim of this study was to identify the causes of a long hospital stay after LC. Methods. This is a retrospective cohort study with 500 successful elective LC patients being included in the analysis. Short hospital stay was defined as being discharged within 24 hours after the operation, whereas long hospital stay was defined as the need for a stay of more than 24 hours after the operation. Results. Using multivariable analysis, ten independent predictive factors were identified for a long hospital stay. These included patients with cirrhosis, patients with a history of previous acute cholecystitis, cholangitis, or pancreatitis, patients on anticoagulation with warfarin, patients with standard-pressure pneumoperitoneum, patients who had been given metoclopramide as an intraoperative antiemetic drug, patients who had been using abdominal drain, patients who had numeric rating scale for pain > 3, patients with an oral analgesia requirement > 2 doses, complications, and private ward admission. Conclusions. LC difficulties were important predictive factors for a long hospital stay, as well as medication and operative factors.
An Analysis of the Network Selection Problem for Heterogeneous Environments with User-Operator Joint Satisfaction and Multi-RAT Transmission
Authors: Escudero-Garzás J. J. , Bousoño-Calzón C.
Published: January 2017

The trend in wireless networks is that several wireless radio access technologies (RATs) coexist in the same area, forming heterogeneous networks in which the users may connect to any of the available RATs. The problem of associating a user to the most suitable RAT, known as network selection problem (NSP), is of capital importance for the satisfaction of the users in these emerging environments. However, also the satisfaction of the operator is important in this scenario. In this work, we propose that a connection may be served by more than one RAT by using multi-RAT terminals. We formulate the NSP with multiple RAT association based on utility functions that take into consideration both user’s satisfaction and provider’s satisfaction. As users are characterized according to their expected quality of service, our results exhaustively analyze the influence of the user’s profile, along with the network topology and the type of applications served.