bluuebunny/crossref_metadata_2025 huggingface dataset:
Spontaneous oesophageal perforation secondary to idiopathic muscular hypertrophy of the oesophagus
Authors: Cathcart M. P. , Thompson H. , Sutton D. G. M.
Published: March 2012

Idiopathic muscular hypertrophy of the oesophagus (IMHO) is reported in equids as an incidental post mortem finding, infrequently associated with clinical signs of oesophageal dysfunction or additional oesophageal abnormalities. Clinicopathological and post mortem findings are presented from a 15‐year‐old gelding that developed a spontaneous perforation of the distal, intrathoracic oesophagus, in association with IMHO. The majority of oesophageal perforations documented in the equine literature have been related to external or iatrogenic trauma resulting in rupture of the cervical portion of the oesophagus. In this case, the early presenting features included pyrexia and inappetance, and progressed over a 4 day period to include signs of tachypnoea, tachycardia and endotoxaemia due to the development of a fatal septic pleuritis and pleural effusion. Oesophageal obstruction was not a presenting feature. Diagnostic investigation in cases of unexplained septic pleural effusion should include oesophageal endoscopic evaluation to rule out perforation of the intrathoracic oesophagus. IMHO may represent a clinically significant, primary disease entity with the potential to lead to oesophageal perforation.
Invariants of reflection groups, arrangements, and normality of decomposition classes in Lie algebras
Authors: Douglass J. Matthew , Röhrle Gerhard
Published: March 2012

Suppose that W is a finite, unitary, reflection group acting on the complex vector space V and X is a subspace of V. Define N to be the setwise stabilizer of X in W, Z to be the pointwise stabilizer, and C=N/Z. Then restriction defines a homomorphism from the algebra of W-invariant polynomial functions on V to the algebra of C-invariant functions on X. In this note we consider the special case when W is a Coxeter group, V is the complexified reflection representation of W, and X is in the lattice of the arrangement of W, and give a simple, combinatorial characterization of when the restriction mapping is surjective in terms of the exponents of W and C. As an application of our result, in the case when W is the Weyl group of a semisimple, complex Lie algebra, we complete a calculation begun by Richardson in 1987 and obtain a simple combinatorial characterization of regular decomposition classes whose closure is a normal variety.
An Approach to Predict Impact of Proposed Engineering Change Effect
Authors: Mehta Chandresh , Patil Lalit , Dutta Debasish
Published: March 2012

Detailed evaluation of a proposed engineering change (EC) or its effects is a time-consuming process requiring considerable user experience and expertise. Therefore, enterprises plan detailed evaluation of only those EC effects that might have a significant impact. Since similar ECs are likely to have similar effects and impacts, past EC knowledge can be utilized for determining whether the proposed EC effect has significant impact. This paper presents an approach for predicting the impact of proposed EC effect based on past ECs that are similar to it. Our approach accounts for the differences in context of impact between attribute values in two changes. The Bayes’ rule is utilized to determine differences in impact value based on the differences in attribute values. The probability values required in Bayes’ rule are determined based on the principle of minimum cross entropy. An example EC knowledge base is created and utilized to evaluate our approach against two state-of-the-art approaches, namely k-nearest neighbor (NN) and regularized local similarity discriminant analysis (SDA). The success rate in predicting impact is used as an evaluation metric. The results show that there is a statistically significant improvement in success rate obtained using our approach as compared to those obtained using the two state-of-the-art approaches. The results also show that for a very large number of proposed ECs, i.e., N > 100, the success rate in predicting impact using our approach shall be greater than that obtained using the two state-of-the-art approaches.
Transient Thermal Model for Proton Exchange Membrane Fuel Cells
Authors: Khemili Faycel , Najjari Mustapha , Nasrallah Sassi Ben
Published: March 2012

This paper presents one-dimensional transient thermal model for the membrane electrode assembly (MEA) of a proton exchange membrane fuel cell (PEMFC). This model accounts for various heat generating mechanisms, including irreversible heat due to electrochemical reactions, entropic heat, and Joule heating arising from the electrolyte ionic resistance. Numerical results show the effects of many important factors on the transient phenomena in the PEMFC system.
Predicting Liquid Water Saturation Through Differently Structured Cathode Gas Diffusion Media of a Proton Exchange Membrane Fuel Cell
Authors: Akhtar N. , Kerkhof P. J. A. M.
Published: March 2012

The role of gas diffusion media with differently structured properties have been examined with emphasis on the liquid water saturation within the cathode of a proton exchange membrane fuel cell (PEMFC). The cathode electrode consists of a gas diffusion layer (GDL), a micro-porous layer and a catalyst layer (CL). The liquid water saturation profiles have been calculated for varying structural and physical properties, i.e., porosity, permeability, thickness and contact angle for each of these layers. It has been observed that each layer has its own role in determining the liquid water saturation within the CL. Among all the layers, the GDL is the most influential layer that governs the transport phenomena within the PEMFC cathode. Besides, the thickness of the CL also affects the liquid water saturation and it should be carefully controlled.
Numerical Analysis of the Possibility of Carbon Formation in Planar SOFC Fueled With Syngas
Authors: Yu Jianguo , Wang Yuzhang , Weng Shilie
Published: March 2012

As one of the most important energy sources, coal can be gasified to syngas in order for it be used in solid oxide fuel cell (SOFC) efficiently and cleanly. However, the big challenge of the utilization of the syngas in SOFC is the carbon formation activity in the Ni/YSZ anode. In this work, according to the fully three-dimensional models of chemical/electrochemical, heat/mass transfer and overpotential, the effects of fuel components on the performance and carbon formation of SOFC were analyzed. From the results, the increment of water steam and carbon dioxide may inhibit the carbon deposition. However, massive water steam and carbon dioxide reduces the output voltage of SOFC as well. The proper molar fraction of hydrogen in syngas also reduces the carbon formation activity. The addition of carbon monoxide may narrow down the region of carbon formation but enhance the carbon formation activity near the fuel inlet of SOFC. Moreover, the existence of methane results in the sharply carbon formation; thus, the methane should be removed as clear as possibly in syngas.
Characterization of Bioelectrochemical Fuel Cell Fabricated With Agriculture Wastes and Surface Modified Electrode Materials
Authors: Paul Subir
Published: March 2012

A bioelectrochemical fuel was fabricated with pretreated and fermented rice husks. The fuel was characterized with variation of process variables by determination of chemical oxygen demand (COD) which is a measure of the oxygen equivalent of electrochemically oxidizable organic fuel to produce electrical energy. The electrodes of the cell were made with nanoporous pure Al coated with platinum, platinum-ruthenium, and platinum-ruthenium-carbon. Anodization parameters were optimized by studying E-I characteristics in sulfuric and oxalic acids with variation of concentration and temperature. Pore size on the order of 30–50 nm was obtained by a two stage anodization. The performance of the cell was evaluated by determining open circuit potential, E-I characteristics, polarization studies, and cyclic voltammetry. A steady onload potential of 600–800 mV was obtained with current density on the order of 15–25 mA/cm2. High power density of 10–15 mW/cm2 has been obtained with electrode materials coated with Pt + Ru or Pt + Ru + C. The performance of coating on nanoporous structure was greatly reflected in the polarization studies, which showed a huge reduction of polarization resistance and increase of exchange current density by many times, the effect being more for anode with anodic solution, fermented rice husk, than with cathode with phosphate buffer cathodic solution. The surface morphology examined by SEM, showed nanodeposits of Pt, Pt-Ru, and the presence of carbon like structure. XRD peaks clearly reveal presence of Pt, Pt-Ru, and carbon.
Fluid Dynamic Investigation of Channel Design in High Temperature PEM Fuel Cells
Authors: Falcucci G. , Jannelli E. , Minutillo M. , Ubertini S.
Published: March 2012

In this paper we analyze the three-dimensional flow field in anode and cathode gas channels of polymer electrolyte membrane (PEM) fuel cells operating at high temperature (T >100 °C). Different gas flow channel designs (pin-type, parallel channels, comb-tipe and multiple serpentine), as well as different channel sections (squared, trapezoidal and rounded with different curvature radii) are evaluated in function of some relevant parameters. The analysis is performed accounting for overall pressure losses, gas distribution over the electrode area and residence time with focus on channel hydraulic diameter, active surface ratio, gas path. Differences with low temperature (LT) PEM fuel cell design are also adressed. The investigation is conducted by means of 3D-CFD softwares and the results of our simulations are compared to experimental data in literature.
A Fatigue Model for Spur Gear Contacts Operating Under Mixed Elastohydrodynamic Lubrication Conditions
Authors: Li S. , Kahraman A. , Klein M.
Published: March 2012

This paper presents a model to predict the crack formation fatigue lives of spur gear contacts operating under mixed lubrication conditions where surface roughnesses introduce intermittent metal-to-metal contacts and severe stress concentrations. The proposed model consists of several submodels, including (i) a gear load distribution model to determine the normal tooth force distribution along the tooth surface, incorporating any profile modifications and manufacturing deviations, (ii) a mixed elastohydrodynamic lubrication model customized to handle transient contact conditions of gears, (iii) a stress formulation that assumes the plane strain condition to compute the transient elastic stress fields on and below the tooth surface induced by the mixed lubrication surface pressure and shear stress distributions, and (iv) a multi-axial fatigue model to predict the crack nucleation life distribution. The proposed spur gear fatigue model is used to simulate the contacts of gear pairs having different surface roughness amplitudes. The predictions are compared to the measured gear fatigue stress-life data for each surface condition to assess the model accuracy in the prediction of the crack nucleation fatigue lives as well as the location of the critical failure sites.
Performance Indices for Collaborative Serial Robots With Optimally Adjusted Series Clutch Actuators
Authors: Lauzier Nicolas , Gosselin Clément
Published: March 2012

Safety is the first priority when designing robots that are intended to physically interact with humans. New robotics standards state as a condition for collaboration that the robot should be designed so that it cannot exert forces larger than 150 N at its tool center point. An effective and reliable way of guaranteeing that this force cannot be exceeded is to place a torque limiter in series with each actuator, thus forming series clutch actuators (SCAs). Since the relationship between the joint limit torques and the achievable end-effector forces is configuration dependent, it is preferable to use adjustable torque limiters. This paper presents a method to optimally control the limit torques of a serial manipulator equipped with adjustable series clutch actuators. It also introduces two performance indices to evaluate the quality of the relationship between the joint limit torques and the achievable end-effector forces. The first one is the ratio of the minimum and maximum force thresholds. Even if it has a strong physical meaning, it is not differentiable everywhere in the workspace and is thus difficult to use in an optimization process based on its gradient. A second index, smooth, and expressed in a closed-form, is therefore introduced which is the determinant of the normalized Jacobian matrix postmultiplied by its transposed. Examples of redundant manipulator motion optimization and of collaborative robot architecture optimization using the second index are shown. The limitations of the proposed approach are that it is based on a static model—which is nevertheless valid under the current safety standards—and that gravity is neglected.
Bio-inspired Passive Skin Cooling for Handheld Microelectronics Devices
Authors: Huang Zhi , Zhang Xinsheng , Zhou Ming , Xu Xiaoding , Zhang Xianzheng , Hu Xuejiao
Published: March 2012

Increasing functionality demands more heat dissipation from the skin of handheld devices. The maximum amount of heat that can be dissipated passively, prescribed by the natural convection and blackbody radiation theories, is becoming the bottleneck. In this letter, we propose a novel bio-inspirited technique that may overcome this passive cooling limit. It is made possible by using a biomimetic skin capable of perspiration on demand. The key component of the biomimetic skin is a thin layer of temperature sensitive hydro gel (TSHG). The TSHG layer can sweat the skin with moisture when the skin temperature is higher than the TSHG’s lower critical solution temperature (LCST), and thus boost the heat dissipation rate through evaporation. The TSHG layer can absorb moisture at low temperature to replenish. With this novel passive cooling technology, a handheld device can have nearly four times more power beyond the traditional passive cooling limit, and may be powerful enough to run a desktop operation system like a full functional personal computer.
Different Types of Instabilities and Complex Dynamics in Reaction-Diffusion Systems With Fractional Derivatives
Authors: Gafiychuk Vasyl , Datsko Bohdan
Published: March 2012

In this article we analyze conditions for different types of instabilities and complex dynamics that occur in nonlinear two-component fractional reaction-diffusion systems. It is shown that the stability of steady state solutions and their evolution are mainly determined by the eigenvalue spectrum of a linearized system and the fractional derivative order. The results of the linear stability analysis are confirmed by computer simulations of the FitzHugh-Nahumo-like model. On the basis of this model, it is demonstrated that the conditions of instability and the pattern formation dynamics in fractional activator- inhibitor systems are different from the standard ones. As a result, a richer and a more complicated spatiotemporal dynamics takes place in fractional reaction-diffusion systems. A common picture of nonlinear solutions in time-fractional reaction-diffusion systems and illustrative examples are presented. The results obtained in the article for homogeneous perturbation have also been of interest for dynamical systems described by fractional ordinary differential equations.
Feedback Linearizing Two-Input Control Systems
Authors: Tall Issa A.
Published: March 2012

We compute explicitly feedback linearizing coordinates for a two-input control system without solving the corresponding PDEs. Our algorithm is based on a successive application of the Frobenius’ theorem and does not necessitate the checking of the involutive conditions for feedback linearization. Examples are provided for illustration.
On Delayed Logistic Equation Driven by Fractional Brownian Motion
Authors: Dung Nguyen Tien
Published: March 2012

In this paper we use the fractional stochastic integral given by Carmona et al. (2003, “Stochastic Integration With Respect to Fractional Brownian Motion,” Ann. I.H.P. Probab. Stat., 39(1), pp. 27–68) to study a delayed logistic equation driven by fractional Brownian motion which is a generalization of the classical delayed logistic equation. We introduce an approximate method to find the explicit expression for the solution. Our proposed method can also be applied to the other models and to illustrate this, two models in physiology are discussed.
Swing Dynamics and Input-Shaping Control of Human-Operated Double-Pendulum Boom Cranes
Authors: Maleki Ehsan , Singhose William
Published: March 2012

Boom cranes are used for numerous material-handling and manufacturing processes in factories, shipyards, and construction sites. All cranes lift their payloads by hoisting them up using overhead suspension cables. Boom cranes move payloads by slewing their base about a vertical axis, luffing their boom in and out from the base, and changing the length of the suspension cable. These motions induce payload oscillation. The problem of payload oscillation becomes more challenging when the payload exhibits double-pendulum dynamics that produce two varying frequencies of oscillation. This paper studies the swing dynamics of such cranes. It also applies input shaping to reduce the two-mode oscillatory dynamics. Experiments confirm several of the interesting dynamic effects.
A Multiphysics Finite Element Model of a 35A Automotive Connector Including Multiscale Rough Surface Contact
Authors: Angadi Santosh V. , Jackson Robert L. , Choe Song-yul , Flowers George T. , Lee Bong-Yi , Zhong Liang
Published: March 2012

Electrical contacts influence the reliability and performance of relays, electrical connectors, high power connectors, and similar systems, and are therefore a key region which needs to be considered. In the current study, a new inclusive multiphysics (involving mechanical, electrical, and thermal fields) finite element model (FEM) of a 35A automotive connector has been developed. The contact resistance is predicted using a multiscale rough surface contact method and is embedded in the multiphysics FEM. The coupled connector model is solved to obtain stresses, displacements, contact pressures, electrical and thermal contact resistances, voltage, current density, and temperature distributions. It appears that the current flows mostly through very small regions that are usually near the contacting surfaces in the connector, thereby suggesting that the available conducting material can be more efficiently used by developing optimized connector designs. Through analytical calculations and experimental measurements of temperature rise (ΔT or change in temperature) for the cable and the connector, it is believed that a large portion of the temperature rise in actual 35A connectors is due to the Joule heating in the supply cables. The model is a powerful tool that can be used for the basic connector characterization, prototype evaluation, and design through various material properties, and surface finishes.
On the Identification of Machine Settings for Gear Surface Topography Corrections (DETC2011-47727)
Authors: Gabiccini Marco , Artoni Alessio , Guiggiani Massimo
Published: March 2012

In this paper, we set out to investigate the performances of some algorithms proposed in the gear literature for identifying the machine-tool settings required to obtain predesigned gear tooth surface topographies, or needed to compensate for flank form deviations of real teeth. For ease of comparison, the problem is formulated as a nonlinear least squares problem, and the most widely employed algorithms are derived as special cases. The algorithms included in the analysis are (i) one-step methods, (ii) iterative methods, and (iii) iterative methods with step control. The performance index is devised in their ability of returning practical solutions in the presence of (i) strong model nonlinearities, (ii) ill-conditioning of the sensitivity matrix, and (iii) demanding topographic shapes. Instrumental here is an original classification of topographic modifications as either “simple” or “complex,” based on the singular value decomposition (SVD) analysis of the sensitivity matrix. Some selected numerical examples demonstrate that iterative techniques with step control are the most convenient in terms of reliability and robustness of the obtained solutions. The generation process considered here is face-milling of hypoid gears, although the methodology is general enough to cope with any gear cutting/grinding method.
The Effect of Spanwise Width on Rectangular Jets With Sidewalls
Authors: Rangarajan Deepak , Curtis Jennifer S.
Published: March 2012

A CFD study on the effect of spanwise width on a rectangular jet with sidewalls is conducted using a standard k-ɛ model with wall functions. An order of magnitude analysis reveals the role played by spanwise turbulent shear terms, arising from the wall bounded flow, as the aspect ratio is decreased at high streamwise distances. A comparative study involving experimental data and other turbulence models is also presented to validate the k-ɛ model for this confined jet flow. It is found that the effect of bounding walls is negligible up to a streamwise distance of at least 105 jet diameters for an aspect ratio of 40, however this distance, within which the flow can be approximated as two-dimensional, decreases with decrease in aspect ratio.
Vortical Structures and Instability Analysis for Athena Wetted Transom Flow with Full-Scale Validation
Authors: Bhushan Shanti , Xing Tao , Stern Frederick
Published: March 2012

Vortical structures and associated instabilities of appended Athena wetted transom flow in full-scale conditions are studied using DES to explain the source of dominant transom flow frequency, including verification and validation using full-scale experimental data. The results are also compared with model-scale bare and appended hull predictions and experiments. The grid used for the validation is sufficiently fine as it resolves 70% and 91% of the experimental inertial subrange and turbulent kinetic energy values, respectively. The model-scale bare and appended hull resistance predictions compare within 2.5%D and 5.4%D of the experimental data D, respectively. The full-scale appended hull resistance predictions compare within 4.2%D of the extrapolated data using the ITTC line. The averaged comparison error of the full-scale transom wave elevation mean, RMS and dominant frequency predictions and the experimental data is 8.1%D, and the predictions are validated at an averaged 11.2%D interval. The transom wave elevation unsteadiness is attributed to the Karman-like transom vortex shedding as both show the same dominant frequency. The Karman-like instability shows St = 0.148 for the bare hull and St = 0.103 ± 4.4% for model- and full-scale appended hull. The appended hull simulations also predict: horseshoe vortices at the juncture of rudder-hull with St = 0.146 ± 3.9% and strut-hull with St = 0.053 ± 2%; shear layer instability at the strut-hull intersection with St = 0.0067 ± 3%; and unsteady sinkage and trim induced by transom vortex shedding with St = 2.19. The instabilities do not show significant variation on scale, propeller or motions. The bare hull simulation also predicts flapping-like instability in the wake with St = 0.144.
Graphene functionalization and seeding for dielectric deposition and device integration
Authors: Garces Nelson Y. , Wheeler Virginia D. , Gaskill D. Kurt
Published: March 2012

Graphene has recently attracted wide-spread attention because of its unique transport and physical properties that are appealing for a wide range of electronic applications. Integration with scalable high-κ dielectrics is important for the realization of graphene-based top-gated electronic devices, including next generation THz applications. Atomic layer deposition (ALD), a low temperature deposition method based on two separate self-limiting surface reactions, is a preferred technique to achieve high-quality, conformal, ultrathin dielectric films with precise control of thickness and chemical composition at the atomic scale. Unfortunately, ALD of oxides on graphene is hindered by the inertness of the graphene surface. To alleviate this graphene-oxide incompatibility, several different functionalization and seeding methods have recently been developed to render the graphene more susceptible to the ALD process of high-κ dielectrics including: ozone, wet chemical and fluorine pretreatments, low-k polymer seed, e-beam metal, and oxide seed layers. The ability of each approach to enable conformal, uniform high-κ dielectrics on graphene while maintaining its inherent transport properties for low power, high-frequency device applications is discussed.
Edme Mariotte and Newton's Cradle
Authors: Cross Rod
Published: March 2012

The first recorded experiments describing the phenomena made popular by Newton's cradle appear to be those conducted by Edme Mariotte around 1670. He was quoted in Newton's Principia, along with Wren, Wallis, and Huygens, as having conducted pioneering experiments on the collisions of pendulum balls. Each of these authors concluded that momentum (then described as the “quantity of motion”) is conserved when one ball collides with another.
The Square Light Clock and Special Relativity
Authors: Galli J. Ronald , Amiri Farhang
Published: March 2012

A thought experiment that includes a square light clock is similar to the traditional vertical light beam and mirror clock, except it is made up of four mirrors placed at a 45° angle at each corner of a square of length L0, shown in Fig. 1. Here we have shown the events as measured in the rest frame of the square light clock. By studying the same cycle of events measured in a frame of reference where the square light clock is in motion with speed of v, we can derive both time dilation and, independently, length contraction. This will be done by analyzing the changing dimensions and also the one-cycle timing for this square light clock.
The Physics of Shot Towers
Authors: Lipscombe Trevor C. , Mungan Carl E.
Published: March 2012

In the late 18th and throughout the 19th century, lead shot for muskets was prepared by use of a shot tower. Molten lead was poured from the top of a tower and, during its fall, the drops became spherical under the action of surface tension. In this article, we ask and answer the question: How does the size of the lead shot depend on the height of the tower? In the process, we explain the basic technology underlying an important historical invention (the shot tower) and use simple physics (Newtonian mechanics and the thermodynamic laws of cooling) to model its operation.
A Flush Toilet Model for the Transistor
Authors: Organtini Giovanni
Published: March 2012

In introductory physics textbooks, diodes working principles are usually well described in a relatively simple manner. According to our experience, they are well understood by students. Even when no formal derivation of the physics laws governing the current flow through a diode is given, the use of this device as a check valve is easily accepted. This is not true for transistors. In most textbooks the behavior of a transistor is given without formal explanation. When the amplification is computed, for some reason, students have difficulties in identifying the basic physical mechanisms that give rise to such an effect. In this paper we give a simple and captivating illustration of the working principles of a transistor as an amplifier, tailored to high school students even with almost no background in electronics nor in modern physics. We assume that the target audience is familiar with the idea that a diode works as a check valve for currents. The lecture emphasis is on the illustration of physics principles governing the behavior of a transistor, rather than on a formal description of the processes leading to amplification.
An Inexpensive Source of High Voltage
Authors: Saraiva Carlos
Published: March 2012

As a physics teacher I like recycling old apparatus and using them for demonstrations in my classes.1–4 In physics laboratories in schools, sources of high voltage include induction coils or electronic systems that can be bought from companies that sell lab equipment. But these sources can be very expensive. In this article, I will explain how you can use a car ignition coil as a high voltage source. Such a coil can be obtained from an old car found in a car salvage yard and used to power cathode ray tubes and discharge tubes to observe the spectra. It can also be used as a source of ignition to simulate explosive combustion that occurs in car engines, rockets, etc. You can also buy these coils in shops that sell car accessories and they are cheaper than induction coils. In Fig. 1 you can see a coil that I used.
Getting the Swing of Surface Gravity
Authors: Thomas Brian C. , Quick Matthew
Published: March 2012

Sports are a popular and effective way to illustrate physics principles. Baseball in particular presents a number of opportunities to motivate student interest and teach concepts. Several articles have appeared in this journal on this topic,1 illustrating a wide variety of areas of physics. In addition, several websites2 and an entire book3 are available. In this paper we describe a student-designed project that illustrates the relative surface gravity on the Earth, Sun, and other solar system bodies using baseball. We describe the project and its results here as an example of a simple, fun, and student-driven use of baseball to illustrate an important physics principle.
Improving Students' Understanding of Waves by Plotting a Displacement-Time Graph in Class
Authors: Wei Yajun
Published: March 2012

The topic of waves is one that many high school physics students find difficult to understand. This is especially true when using some A-level textbooks1,2used in the U.K., where the concept of waves is introduced prior to the concept of simple harmonic oscillations. One of the challenges my students encounter is understanding the difference between displacement-time graphs and displacement-position graphs. Many students wonder why these two graphs have the same sinusoidal shape. Having the students use multimedia simulations allows them to see, in a hands-on fashion, the relationship between the two graphs.
A Stand-Alone Interactive Physics Showcase
Authors: Pfaff Daniel , Hagelgans Anja , Weidemüller Matthias , Bretzer Klaus
Published: March 2012

We present a showcase with interactive exhibits of basic physical experiments that constitutes a complementary method for teaching physics and interesting students in physical phenomena. Our interactive physics showcase, shown in Fig. 1, stimulates interest for science by letting the students experience, firsthand, surprising phenomena and teaching physical concepts. By letting the students interact with the experiments under optimum safety conditions and with good protection against vandalism, our approach complements interactive simulations, e.g., as offered by the Physics Education Technology project.1
Pulse speed on a plucked wire
Authors: Odekirk Tristan , Slaton William V.
Published: March 2012

This paper serves to update an elegant experiment published in The Physics Teacher to measure the speed of a pulse on a taut metal wire.1 Unfortunately, commercially available units2 that serve the same purpose are priced outside the range of most high school or college physics teaching laboratories. Wakeland et al. show how an affordable adaptation of the traditional standing wave apparatus using taut metal wire and horseshoe magnets can be used to measure the speed of a pulse by using an oscilloscope to measure an induced voltage in the wire as the pulse transverses the middle of the magnets, which are a known distance apart.
PB13 The Four-Hour Rule: time for a new approach?
Authors: Mackenzie A , O'Donnell R D W
Published: March 2012

Objectives and Background

The “Four-Hour Rule” (FHR) was introduced in Scotland in 2007 and remains in effect. In England and Wales this has been replaced by a range of quality indicators that came into effect on 1st April 2011. We assessed the compliance of a central Glasgow Emergency Department (ED) with Scottish standards for the FHR, how well said ED complies with new time-based quality measures and investigated the correlation between the FHR and other time-based quality indicators. Patient encounters from a central Glasgow ED spread over two consecutive days were retrospectively captured using the ED Information System.

Methods

487 patient encounters were captured. Following exclusion criteria n=472. Mean length of time spent in the ED=2.20 h. In 2.75% (13) patient encounters total time spent in the ED was >4 h. For 3.25% (4) of 123 patients arriving by ambulance time to initial assessment was longer than the published 20 min target. Median time to treatment=51.0 min (target: median=60.0 min).

Results and Conclusions

Analysis of this dataset suggests that the study ED may not be meeting the Scottish government target of “98% of patients seen then admitted, transferred or discharged within 4 h” The study ED does, however, achieve the College of Emergency Medicine target of 95%. When the new time-based quality measures are applied to the same dataset the study ED is shown to be achieving the median target time to treatment of 60 min but does not achieve the target of 100% patient arriving by ambulance receiving an initial assessment within 20 min of arrival. There is no meaningful correlation between time to initial assessment and total time spent in ED (r=0.033, p=0.71) but a reasonable correlation between time to treatment and total time spent in ED (r=0.409, p=0.000001).
PB19 The use of individual performance metrics to reduce prescribing errors in the emergency department
Authors: Tiah L
Published: March 2012

Objectives and Background

Our emergency department (ED) receives a new cohort of junior doctors every 6 months as part of the national manpower allocation to meet health service needs. Prescribing errors by these doctors tend to be higher at the beginning of their postings followed by some improvement as they adapt to the work in ED but the magnitude and the direction of this change for each cohort has not been consistent. In an attempt to address this problem, an approach involving the use of metrics to drive individual performances through monthly plan-do-check-act cycles was implemented in May 2009. The monthly tally of prescribing errors became one of the key performance indicators for the junior doctors.

Methodology

Monthly broadcasting of prescribing error counts by each doctor allows them to benchmark individual performances against one another and provides a reference for self-improvement for the following month. The monthly tally of prescribing errors are also computed into a pre-determined formula and translated into their monthly social fund as incentive for the whole cohort to keep the prescription errors as low as possible. A control chart of the monthly tally was plotted based on a total of 48 data points for 8 cohorts over 4 years from May 2007 to April 2011 to monitor the impact of the intervention.

Results

The monthly tally showed a shift towards fewer counts of prescribing errors in the post-intervention phase, with a mean of 29 (upper control limit 45, lower control limit 13) among the pre-intervention cohorts compared to a mean of 18 (upper control limit 31, lower control limit 6) among the post-intervention cohorts.

Conclusion

The use of metrics has helped to drive and sustain a reduction in prescribing errors among junior doctors as a cohort during their 6-month postings in our ED.
PB20 Analysis of Complaints Lodged by Emergency Department Patients in a Teaching Hospital in Hong Kong
Authors: Wai A , Rainer T
Published: March 2012

Objectives and Background

Emergency departments (ED) are notorious for its high complaint rate by patients because EDs are usually congested with a large number of patients and the waiting time is long. Consultation time for each patient would be very limited. Short consultation and limited availability of diagnostic investigations contribute to diagnostic challenges and errors.

Methods

This is a retrospective quantitative review of complaints against EDs lodged by patients through the Public Relations Office in 2009 & 2010. The demographics of these patients and their attendances were recorded. The issues were categorised into the following: Communication, Access, Treatment, Rights, Administration, Environment and Cost. The data was compared with our previous publication on complaint in 1990–1994.

Results

There were 114 complaints lodged in 2009–2010 (72 in 1990–1994). Apparently the age, residential district and billing patterns of these complaint patients were comparable with our overall distribution. Complaint rate would be higher during overnight shift. For urgent cases, compliant validity is 86%; (65% in 1990–1994); for non-urgent cases, validity is 78% (58% in 1990–1994). In our data, 45% were diagnosis and treatment related (it was 29% in 1990–1994). 50% were related to missing diagnosis and improper management. Around 30% is related to inadequacy of care. Proper referral and more detailed explanation is likely a solution to lower the complaint rate. In terms of specialty distribution, orthopaedics (29%) was the group with the highest risk.

Conclusions

The number of complaint cases studied was still small. We would recommend establishing a database for prospective analysis so that we can detect unforeseeable problems soon after they happened and we may act accordingly to minimise further occurrence. These cases may be reported on a half-yearly basis to all department staff, in a sharing attitude, to help colleagues to learn and beware of these problems. This should be a good start of “patient-centred care.”
Partner notification uptake for sexually transmitted infections in China: a systematic literature review
Authors: Wang Alberta L , Peng Rui-Rui , Tucker Joseph D , Cohen Myron S , Chen Xiang-Sheng
Published: March 2012

Objective

China's sexually transmitted infection (STI) epidemic requires comprehensive control programmes. Partner services are traditional pillars of STI control but have not been widely implemented in China. This study was a systematic literature review to examine STI partner notification (PN) uptake in China.

Methods

Four English and four Chinese language databases were searched up to March 2011 to identify articles on PN of STIs including HIV in China. PN uptake was defined as the number of partners named, notified, evaluated or diagnosed per index patient.

Results

A total of 11 studies met inclusion criteria. For STI (excluding HIV) PN, a median 31.6% (IQR 27.4%–65.8%) of named partners were notified, 88.8% (IQR 88.4%–90.8%) of notified partners were evaluated and 37.9% (IQR 33.1%–43.6%) of evaluated partners were diagnosed. For HIV PN, a median 15.7% (IQR 13.2%–36.5%) of named partners were notified, 86.7% (IQR 72.9%–90.4%) of notified partners were evaluated and 27.6% (IQR 24.1%–27.7%) of evaluated partners were diagnosed. A mean of 80.6% (SD=12.6%) of patients attempted PN, and 72.4% (IQR 63.8%–81.1%) chose self-referral when offered more than one method of PN. Perceived patient barriers included social stigma, fear of relationship breakdown, uncertainty of how to notify and lack of partner contact information. Perceived infrastructure barriers included limited time and trained staff, mistrust of health workers and lack of PN guidelines.

Conclusion

PN programmes are feasible in China. Further research on STI PN, particularly among men who have sex with men and other high-risk groups, is an important public health priority. PN policies and guidelines are urgently needed in China.
DIRAC EQUATION IN THE MAGUEIJO–SMOLIN APPROACH OF DOUBLY SPECIAL RELATIVITY
Authors: BELHADI Z. , MÉNAS F. , BÉRARD A. , GOSSELIN P. , MOHRBACH H.
Published: March 2012

We reconsider in details the Dirac equation in the context of the Magueijo–Smolin approach to the Doubly Special Relativity. Starting from the deformed dispersion relation we focus on obtaining a Dirac equation in momentum space, allowing us to achieve a more in-depth study of its semiclassical approach. Finally by means of a "deformed correspondence principle" we gain access to an equation in the position space.
CALCULATION OF THE ANOMALOUS MAGNETIC MOMENT OF μ IN A MODEL OF ELECTROWEAK-SCALE RIGHT-HANDED NEUTRINOS
Authors: BU JIAN-PING , JIA BEI
Published: March 2012

The lepton flavor violating process μ → eγ has been previously studied in a model of electroweak-scale right-handed neutrinos. We had calculated the decay amplitude in unitarity gauge [J. P. Bu, Y. Liao and J. Y. Liu, Phys. Lett. B665, 39 (2008)] and Rξ gauge [J. P. Bu, Commun. Theor. Phys.53, 703 (2010)]. In this paper, we calculate the anomalous magnetic moment of μ in Rξ gauge.
STRUCTURAL, MAGNETIC AND DIELECTRIC PROPERTIES OF Fe-DOPED BaTiO3 SOLIDS
Authors: GUO ZHENGANG , YANG LIHONG , QIU HONGMEI , ZHAN XUEDAN , YIN JINHUA , CAO LIPENG
Published: March 2012

The structural, ferroelectric and magnetic properties of bulk perovskite Fe -doped BaTiO 3 (BFTO) prepared by standard solid-state reaction have been investigated. X-ray diffraction (XRD) identifies the tetragonal structure of BFTO samples. Rietveld refinements of XRD data indicates that the doping ions led to ab-plane expansion and out-of-ab-plane shrinkage of the BFTO phases. X-ray photoelectron spectroscopy (XPS) measurements for the prepared samples reveals that Fe 3+ and Fe 4+ ions replaces Ti 4+ ions in the crystal lattice to form single-phase BFTO solids. The results of the temperature-dependent dielectric properties and magnetic hysteresis loops for the BFTO solids show simultaneously the ferroelectric order and ferromagnetic order at room temperature. The doping of magnetic element Fe brings about ferromagnetic order for the samples, and the measured magnetic moment for each Fe atom increases from 0.70 μB to 1.55 μB in BFTO samples. The origin of ferromagnetism of the BFTO samples should be attributed to the double exchange interactions of Fe 3+– O 2– Fe 4+ ions.
STRUCTURAL, ELECTRONIC, AND MAGNETIC PROPERTIES OF BIMETALLIC TinMn13-n (n = 1–12) CLUSTERS FROM DENSITY FUNCTIONAL CALCULATIONS
Authors: LI TONGWEI , FENG ZHENJIE , JING CHAO , HONG FENG , CAO SHIXUN , ZHANG JINCANG
Published: March 2012

The structural, electronic and magnetic properties of icosahedral bimetallic Ti n Mn 13-n (n = 1–12) clusters were investigated by the density-functional method. The results show that the central position is occupied by a manganese atom in the most stable structures. The total magnetic moment decreases with the increase of Ti atoms. It is interesting and important to note that, from the local magnetic moment, all Ti atoms are ferromagnetic coupling in various clusters, and most Mn atoms have the same feature. However, the spins between Ti and Mn atoms except for Ti 12 Mn 1 are anti-parallel, i.e. an antiferromagnetic couple on magnetic structure. All the above are discussed in terms of magnetic ordering theory.
FAST MEASUREMENT OF HYPERSPACE VECTORS IN NOISE-BASED LOGIC
Authors: STACHÓ L. L.
Published: March 2012

We propose a method to determine single hyperspace vectors (product strings of noise-bits) by classical means with the same effectiveness as the results using time shifted noise-based logic. A system of binary linear equations based on the amplitudes of the hyperspace vector and the reference noise-bits is set up and solved after enough independent information is collected. The resulting error probability (the chance of getting no answer) has approximately an exponential decay with the time of measurement.
NEW NOISE-BASED LOGIC REPRESENTATIONS TO AVOID SOME PROBLEMS WITH TIME COMPLEXITY
Authors: WEN HE , KISH LASZLO B. , KLAPPENECKER ANDREAS , PEPER FERDINAND
Published: March 2012

Instantaneous noise-based logic can avoid time-averaging, which implies significant potential for low-power parallel operations in beyond-Moore-law-chips. However, in its random-telegraph-wave representation, the complete uniform superposition (superposition of all N-bit binary numbers) will be zero with high probability, that is, non-zero with exponentially low probability, thus operations with the uniform superposition would require exponential time-complexity. To fix this deficiency, we modify the amplitudes of the signals of L and H states and achieve an exponential speedup compared to the old situation. Another improvement concerns the identification of a single product-string (hyperspace vector). We introduce "time shifted noise-based logic", which is constructed by shifting each reference signal with a small time delay. This modification implies an exponential speedup of single hyperspace vector identification compared to the former case and it requires the same, O(N) complexity as in quantum computing.
ACCURACY VERSUS SPEED IN FLUCTUATION-ENHANCED SENSING
Authors: MAKRA P. , TOPALIAN Z. , GRANQVIST C. G. , KISH L. B. , KWAN C.
Published: March 2012

Fluctuation-enhanced sensing (FES) comprises the analysis of the stochastic component of the sensor signal and the utilization of the microscopic dynamics of the interaction between the agent and the sensor. We study the relationship between the measurement time window and the statistical error of the measurement data in the simplest case, when the output is the mean-square value of the stochastic signal. This situation is relevant at any practical case when the time window is finite, for example, when a sampling of the output of a fluctuation-enhanced array takes place; or a single sensor's activation (temperature, etc.) is stepped up; or a single sensor's output is monitored by sampling subsequently in different frequency windows. Our study provides a lower limit of the relative error versus data window size with different types of power density spectra: white noise, 1/f(flicker, pink) noise, and 1/f2 (red) noise spectra.
SUPPRESSING PHASE LOCKED LOOP GAIN FLUCTUATIONS IN WIDEBAND LINEARLY FREQUENCY MODULATED WAVEFORM SYNTHESIZERS
Authors: WANG WEN-QIN
Published: March 2012

Wideband linearly frequency modulated (LFM) signals are required for many communication navigation applications; however, a limiting factor is the presence of frequency nonlinearity which degrades the system performance significantly. The fluctuations of phase locked loop (PLL) loop gain and voltage controlled oscillator (VCO) gain will results in inconsistent frequency nonlinearity performance in the whole frequency band. In this letter, we propose an effective solution by real-timely tuning the phase/frequency detecting current, along with the iterative compensation algorithm. In this way, the frequency nonlinearity is compensated and a wideband LFM waveform synthesizer can be designed. This approach is validated by experimental results.