bluuebunny/crossref_metadata_2025 huggingface dataset:
Experiments on the Biporous Micropillar Array for Enhanced Heat Transfer Performance
Authors: He Bin , Wei Mengyao , Liang Qian , Tan Chuan Seng , Wang Evelyn N.
Published: March 2016

A mathematical model has been developed in previous work to optimize the parameters of the biporous structures with micro channels among pillars to reduce the viscous force by shortening the liquid prorogation length inside porous media. In this paper, an experimental rig has been built to test the performance of the designed samples at ambient conditions according to the previous derived mathematical model. The pillar areas of the samples have been fabricated by photolithograph and Deep Reactive-Ion Etching (DRIE) with varied parameters for further comparisons. To simulate the concentrated heating of a working device and measure its temperature, a Pt heater and four Resistance Thermal Detectors (RTDs) have been fabricated by the electron beam deposition and lift-off process. The sample has been mounted horizontally to a water-proof sample holder, and the de-ionized water has been pumped into the evaporator through a reservoir by a syringe pump. By fine tuning the pumping rate, one can reach the minimum pumping rate while maintaining the water levels of the reservoir and the evaporator without drying out for a certain heating power. The mathematical model has be partially verified by the experimental results, which paves the way for the final design of the silicon vapor chamber.
Characterization of Thermal Resistances Across CVD-Grown Graphene/Al2O3 and Graphene/Metal Interfaces Using Differential 3-Omega Technique
Authors: Villaroman Daniel Josephus , Dai Weijing , Wang Xinjiang , Gan Lin , Wu Ruizhe , Luo Zhengtang , Huang Baoling
Published: March 2016

Chemical vapor deposited (CVD) graphene together with a superior gate dielectric such as Al2O3, is a promising combination for next-generation high-speed field effect transistors (FET). These high-speed devices are operated under high frequencies and will generate significant heat, requiring effective thermal management to ensure device stability and longevity. It is thus of importance to characterize the interfacial thermal resistance (ITR) between graphene/Al2O3 gate dielectric and graphene/metal contacts.

In this work, ITRs across the single-layer graphene/Al2O3 and the graphene/metal (Al, Ti, Au) interfaces were characterized from 100 K to 330 K using the differential 3ω method. Unlike previous works which mostly used exfoliated single or few-layer graphene, we used CVD large-scale graphene, which is most promising for FET fabrication due to cost and quality control, in the experiments. To ascertain the measured results and reduce uncertainty, different sandwich configurations including metal/graphene/metal, Al2O3/graphene/Al2O3 and metal/graphene/Al2O3 were used for the measurements. The effects of post annealing on different interfaces were also investigated.

Measurements of numerous samples showed an average ITR at 300K of 9×10−8 m2K/W for graphene/Al2O3, 6×10−8 m2K/W for graphene/Al, 5×10−8 m2K/W for graphene/Ti, and 7×10−8 m2K/W for graphene/Au interfaces. For the metal interfaces with graphene, the results are within the same order of magnitude as previous measurement results with graphite. However, ITR for graphene/Al2O3 is one order of magnitude higher than those reported for graphene/SiO2 interfaces. The measured ITRs for both metal and dielectric interfaces with graphene are almost temperature-independent from 100 K to 330 K, indicating that phonons are the major heat carrier. Annealing was found to have different effects on different interfaces. For graphene/Ti interfaces, ITR results measured before and after annealing consistently show a reduction of around 20%. However, such improvements on interfacial conductance were not observed for graphene/Al, graphene/Au and graphene/Al2O3 interfaces. The reduction of ITR of graphene/Ti interface is perceived to stem from the formation of Ti-C covalent bonds. However, neither the commonly used maximum transmission model nor the diffuse mismatch model explicitly considers bonding effects at the interface, which is why they poorly predict and explain all the aspects of the measurements. An improvement to the classic anisotropic DMM model was proposed by taking into account different bonding types and bonding area between graphene and Al2O3/metal layer, resulting in a better fitting with the experimental data.
Numerical Investigation on Head-On Collisions of Binary Micro-Droplets by an Improved Multiphase Lattice Boltzmann Flux Solver
Authors: Wang Y. , Shu C.
Published: March 2016

Head-on collisions of binary micro-droplets are of great interest in both academic research and engineering applications. Numerical simulation of this problem is challenging due to complex interfacial changes and large density ratio between different fluids. In this work, the recently proposed lattice Boltzmann flux solver (LBFS) is applied to study this problem. The LBFS is a finite volume method for the direct update of macroscopic flow variables at cell centers. The fluxes of the LBFS are reconstructed at each cell interface through lattice moments of density distribution functions (DDFs). As compared with conventional multiphase lattice Boltzmann method, the LBFS can be easily applied to study complex multiphase flows with large density ratio. In addition, external forces can be implemented more conveniently and the tie-up between the time step and mesh spacing is also removed. Moreover, it can deal with complex boundary conditions directly as those do in the conventional Navier-Stokes solvers.

At first, the reliability of the LBFS is validated by simulating a micro-droplet impacting on a dry surface at density ratio 832 (air to water). The obtained result agrees well with experimental measurement. After that, numerical simulations of head-on collisions of two micro droplets are carried out to examine different collisional behaviors in a wide range of Reynolds numbers and Weber numbers of 100 ≤ Re ≤ 2000 and 10 ≤ We ≤ 500. A phase diagram parameterized by these two control parameters is obtained to classify the outcomes of these collisions. It is shown that, at low Reynolds number (Re=100), two droplets will be coalescent into a bigger one for all considered Weber numbers. With the increase of the Reynolds number, separation of the collision into multiple droplets appears and the critical Weber number for separation is decreased. When the Reynolds number is sufficiently high, the critical Weber number for separation is between 20 and 25.
Experimental Study on Heat Transfer of Multi-Walled Carbon Nanotubes/Water Nanofluids in Horizontal Microtubes
Authors: Karimzadehkhouei Mehrdad , Khalili Sadaghiani Abdolali , Şendur Kürşat , Mengüç M. Pınar , Koşar Ali
Published: March 2016

In this study, heat transfer characteristics of multi-walled carbon nanotube based nanofluids were investigated in horizontal microtubes with outer and inner diameters of ∼1067 and ∼889 μm, respectively. Carbon nanotubes (CNTs) with outer diameter of 10–20 nm and length of 1–2 micron as non-spherical nanoparticles were used for nanofluid preparation, where water was considered as basefluid. Nanofluid was characterized using the Scanning Electron Microscopy (SEM). According to obtained results, deposited CNTs have considerable effect on the convective heat transfer inside the microtube.
Effects of Surface Wetting Characteristics on Start-Up Performance of an Oscillating Heat Pipe
Authors: Hao Tingting , Ma Xuehu , Lan Zhong
Published: March 2016

A simultaneous visualization and heat performance of oscillating heat pipes (OHPs) were performed. Experiments were performed under different surface wetting characteristics. Results showed that the start-up performance was improved on hydrophilic OHP as opposed to the copper OHP. A small bubble grew quickly and became a vapor plug in the evaporation section with hydrophilic surface. The process of vapor expansion and contraction accompanying liquid slug movement upward and backward continued to occur as a spring, and the OHPs started up. However, the hydrophobic OHP failed to start up. For the superhydrophobic OHP, nucleate boiling took place in the evaporation section, and the bubble expansion and contraction phenomenon were not observed. Heat transfer results showed that wall temperature fluctuations were observed at the start-up stage. The start-up time for the hydrophilic OHP was lowest and the amplitudes of temperature oscillations were increased in hydrophilic OHP compared to the copper OHP.
Numerical Simulation of Convective Heat Transfer Characteristics of Aviation Kerosene Inside Elliptical Tubes Under Supercritical Pressure
Authors: Zhang Jingzhi , Zhou Naixiang , Lin Jinpin , Lin Han , Li Wei
Published: March 2016

Heat transfer characteristics of aviation kerosene were investigated numerically using a three-dimensional model. The influence of the ratio of longer axis to short axis of elliptical tubes (r), inlet Reynolds number (Re), and pressure (P) of kerosene on local heat transfer characteristics were discussed in detail. The results indicate that the heat transfer coefficient (h), wall temperature (Tw), and bulk fluid temperature (Tb) increase along Z axis direction from inlet to outlet when P=4Mpa. h increases with increasing r and Re, while Tw decreases with increasing Re and r. Tb decreases with increasing Re and remains stable for a varying r. For P=3Mpa, the deterioration of heat transfer occurs near the outlet of computational geometry, where the temperature of near wall region fluid exceeds the critical point and specific heat decrease dramatically. A correlation for heat transfer coefficient of aviation kerosene at supercritical pressure inside elliptical tubes is proposed and compared with the present simulation data. It is shown that this correlation can predict the simulation data within an ±15% error band. Compared with circular tubes, elliptical tubes can enhance the heat transfer effect and decrease the wall temperature, thus enhance the security of the operating system.
Mixing Simulations of a Wankel Pump as a Micromixer
Authors: Wan S. , Lau M. S. W. , Leong J. , An N. , Goh K. L.
Published: March 2016

The present work was movitated by an earlier study on pumps based on a Wankel geometry (Wankel pumps) which revealed a flow structure, rich in three dimensional vortices (including Taylor like counter-rotating ones), in the pump chamber, suggesting the possibility of a Wankel pump of also functioning as a mixer. To this end, numerical mixing experiments were run using the general scalar transport equation to model the evolution of species concentration. Interestingly, it was observed that species dispersion occurs predominantly sideways (laterally) and that vertical dispersion is almost non-existent. In other words, for binary mixing of two species with a Wankel pump, they must be introduced side by side to ensure effective mixing.
One-Time Multi-Depth Silicon Etching Method Based on SiO2 Masking Layer
Authors: Tan Xiao , Tao Zhi , Xu Tiantong , Li Haiwang
Published: March 2016

In order to improve the possibility of successful bonding and performance of structures, the new method for multi-depth silicon etching is required. This paper aims to design and create a new method for one-time multi-depth silicon etching in manufacturing complex structures based on SiO2 masking layer. The core idea of this method is that: Firstly, all patterns are transferred into photo resist through photo etching; Then etch pattern will be transferred in the SiO2 masking layer by multi-time shallow etching with different time etching control; Finally, patterns will be transferred to the silicon wafer with uniform ratio based on the measured etching selectivity of SiO2-Si with one time.

In the experiments, the process is completed in the silicon wafer with SiO2 masking layer whose thickness is elaborately designed. Firstly, the etching rate of SiO2 and the etching selectivity of SiO2-Si were measured accurately. Secondly, the shallow structure based on the designed structure, the etching rate of SiO2 and the etching selectivity of SiO2-Si is etched on the SiO2masking layer. The second step forms different thickness version of SiO2 masking layer. At last, the SiO2 masking layer is etched until final structure and consequently different depth of groove accomplish due to various thickness of SiO2 etched by previous step.

The experimental results indicated that the new methods has at least three advantages compared to traditional method: That is faster efficiency, higher cleanness and more complex structure. Fast work efficiency owes to only SF6 etching rather than two gases of SF6 and C4F8 to reduce half of time. Also high cleanness comes from being not exposed to air and researchers directly. The largest benefit of new method may be that can create more complex structure for higher required machine design and for higher mechanical function. It is because that normal etching method could only build few different depth of grooves due to multi-process limitation and contrary to normal one, new method can create more different depth of groove. And more different depth of groove means that more complex structure can be designed.
Unit Cell Model Formulation and Thermal Performance Analysis for Cross-Flow Heat Exchanger
Authors: Zhang Hengyun , Wang Zhaoqiang , Wang Yansong
Published: March 2016

An analysis for the cross-flow heat exchanger is conducted for electronic cooling applications, with the design goal of dissipating 175W from high power chip by maintaining the chip temperature within 85 °C in a compact space. Liquid to liquid heat exchanger in cross flow arrangement is preferred due to its compact size and high effectiveness. A volume averaging formulation is developed to determine the heat transfer coefficient at the unit cell level. The effects of channel shape, channel size, and heat exchanger material are examined through the heat transfer in the unit cell model. The obtained heat transfer coefficients are also used for the estimation of the heat exchanger thermal performance based on the effectiveness-NTU method. To verify the volume averaging formulation, a full field heat and fluid flow over the cross-flow heat exchangers are investigated through numerical computation. The amount of heat exchanged is extracted and compared with the unit cell model prediction. A fairly good agreement is obtained between the two approaches. Fabrication of cross-flow heat exchanger is further discussed to meet the design target.
Enhanced Flow Boiling in Microchannels Using Auxiliary Channels and Multiple Micronozzles
Authors: Li Wenming , Yang Fanghao , Alam Tamanna , Peng Benli , Qu Xiaopeng , Li Chen
Published: March 2016

Flow boiling in an array of five parallel microchannels (W=200 μm, H=250 μm, L=10 mm) can be dramatically enhanced using self-excited and self-sustained high frequency two-phase oscillations induced by two-nozzle configuration. However, the effect of the two-phase oscillations is confined to the downstream of the microchannels. In this study, four-nozzle microchannel configuration is developed with an aim to extend mixing to the entire channel. Flow boiling in the four-nozzle microchannel is experimentally studied with deionized water over a mass flux range of 120 to 600 kg/m2 s. Overall average heat transfer coefficient (HTC) is significantly enhanced approximately 54.5% by extending the enhanced multi-channel mixing to the whole channel. It is equally important that the pressure drop can be further reduced by approximately 50%. Compared with previous two-nozzle design, four-nozzle configuration not only extends the mixing to the whole channel but also increase nucleation sites, which has been confirmed by visualization study to promote nucleation boiling.
Reactive Molecular Dynamics Simulation of Graphene-Based Nanomaterials Produced by Confined Heating of Polymer
Authors: Dong Yuan , Lin Jian
Published: March 2016

The graphene-based nanomaterial has great potential as catalyst and supercapacitors. In this paper we study the pyrolysis of polymers in a nanosecond time scale with the reactive molecular dynamics (MD) simulations using ReaxFF potential. It is found that the confined heating will produce graphene-like nanostructures out of two kinds of polymers: polyimide and polyether ether ketone. The peak pressure achieves above 3GPa with a processing temperature of 3000K. It indicates that the local high temperature and pressure can convert polymer to graphene-based nanomaterials without metal catalyst, which may enable large scale production of high performance electrical devices and microreactors with laser scribing method.
Solidification Analysis of Density-Graded Closed-Cell Metallic Foam Under Constant Temperature Boundary Condition
Authors: Wang W. B. , Yang X. H. , Zhang Q. C. , Lu T. J.
Published: March 2016

In the industrial fabrication processes of density-graded closed-cell metallic foams, it is of great importance to control the solidification immediately after foams are formed so as to obtain the final products with well distributed density-graded pores and less defects. This paper presented an analytical work aiming to predict the solidification front of density-graded metallic foam under constant temperature boundary condition. Numerical simulations based on ideal density-graded circular pores demonstrated good agreement with the analytical solutions. The 2D porous morphology of a real density-graded aluminum foam was further reconstructed with microCT, on the basis of which the propagation of solidification front inside this real density-graded foam was numerically investigated. An equivalent shape factor for this real foam was calculated to provide an insight for the influence of different pore shapes on solidification. Compared with other pores, the solidification speed of elliptical pores (a common pore shape in real foams) is moderate, i.e., slower than circular pores but quicker than triangular pores for same porosity.
Effect of Heat Sink Structure Improvement on Heat Dissipation Performance in High Heat Flux
Authors: Cui Zhuo
Published: March 2016

This paper presents the effects of heat dissipation performance of pin fins with different heat sink structures. The heat dissipation performance of two types of pin fin arrays heat sink are compared through measuring their heat resistance and the average Nusselt number in different cooling water flow. The temperature of cpu chip is monitored to determine the temperature is in the normal range of working temperature. The cooling water flow is in the range of 0.02L/s to 0.15L/s. It’s found that the increase of pin fins in the corner region effectively reduce the temperature of heat sink and cpu chip. The new type of pin fin arrays increase convection heat transfer coefficient and reduce heat resistance of heat sink.
Design of Open System of Loop Heat Pipe Experimental Rig for Phase Change Driving Force and Visual Experiment Study
Authors: Zhu Kai
Published: March 2016

The open system of visual loop heat pipe experimental rig driven by phase change of the refrigerant is established, which is used to research the effect of parameters of the volume, supplementary of refrigerant, properties of wick, height of evaporation cavity and heating power on the performance of this system quantitatively, also the heat transfer characteristics of refrigerant flow in the evaporator visually is studied. We observed and researched the whole process of system from the start up to the stable condition in the evaporator, the changes of refrigerant which is from boiling to the gas-liquid separation. From the experimental point of view, it provides a basis for the establishment of the closed system and for the creation of new mathematical model of the driving mechanism.
Automated detection of vessel lumen and stent struts in intravascular optical coherence tomography to evaluate stent apposition and neointimal coverage
Authors: Nam Hyeong Soo , Kim Chang‐Soo , Lee Jae Joong , Song Joon Woo , Kim Jin Won , Yoo Hongki
Published: March 2016

Purpose:

Intravascular optical coherence tomography (IV‐OCT) is a high‐resolution imaging method used to visualize the microstructure of arterial walls in vivo. IV‐OCT enables the clinician to clearly observe and accurately measure stent apposition and neointimal coverage of coronary stents, which are associated with side effects such as in‐stent thrombosis. In this study, the authors present an algorithm for quantifying stent apposition and neointimal coverage by automatically detecting lumen contours and stent struts in IV‐OCT images.

Methods:

The algorithm utilizes OCT intensity images and their first and second gradient images along the axial direction to detect lumen contours and stent strut candidates. These stent strut candidates are classified into true and false stent struts based on their features, using an artificial neural network with one hidden layer and ten nodes. After segmentation, either the protrusion distance (PD) or neointimal thickness (NT) for each strut is measured automatically. In randomly selected image sets covering a large variety of clinical scenarios, the results of the algorithm were compared to those of manual segmentation by IV‐OCT readers.

Results:

Stent strut detection showed a 96.5% positive predictive value and a 92.9% true positive rate. In addition, case‐by‐case validation also showed comparable accuracy for most cases. High correlation coefficients (R > 0.99) were observed for PD and NT between the algorithmic and the manual results, showing little bias (0.20 and 0.46 μm, respectively) and a narrow range of limits of agreement (36 and 54 μm, respectively). In addition, the algorithm worked well in various clinical scenarios and even in cases with a low level of stent malapposition and neointimal coverage.

Conclusions:

The presented automatic algorithm enables robust and fast detection of lumen contours and stent struts and provides quantitative measurements of PD and NT. In addition, the algorithm was validated using various clinical cases to demonstrate its reliability. Therefore, this technique can be effectively utilized for clinical trials on stent‐related side effects, including in‐stent thrombosis and in‐stent restenosis.
Fast multipurpose Monte Carlo simulation for proton therapy using multi‐ and many‐core CPU architectures
Authors: Souris Kevin , Lee John Aldo , Sterpin Edmond
Published: March 2016

Purpose:

Accuracy in proton therapy treatment planning can be improved using Monte Carlo (MC) simulations. However the long computation time of such methods hinders their use in clinical routine. This work aims to develop a fast multipurpose Monte Carlo simulation tool for proton therapy using massively parallel central processing unit (CPU) architectures.

Methods:

A new Monte Carlo, called MCsquare (many‐core Monte Carlo), has been designed and optimized for the last generation of Intel Xeon processors and Intel Xeon Phi coprocessors. These massively parallel architectures offer the flexibility and the computational power suitable to MC methods. The class‐II condensed history algorithm of MCsquare provides a fast and yet accurate method of simulating heavy charged particles such as protons, deuterons, and alphas inside voxelized geometries. Hard ionizations, with energy losses above a user‐specified threshold, are simulated individually while soft events are regrouped in a multiple scattering theory. Elastic and inelastic nuclear interactions are sampled from ICRU 63 differential cross sections, thereby allowing for the computation of prompt gamma emission profiles. MCsquare has been benchmarked with the gate/geant4 Monte Carlo application for homogeneous and heterogeneous geometries.

Results:

Comparisons with gate/geant4 for various geometries show deviations within 2%–1 mm. In spite of the limited memory bandwidth of the coprocessor simulation time is below 25 s for 107 primary 200 MeV protons in average soft tissues using all Xeon Phi and CPU resources embedded in a single desktop unit.

Conclusions:

MCsquare exploits the flexibility of CPU architectures to provide a multipurpose MC simulation tool. Optimized code enables the use of accurate MC calculation within a reasonable computation time, adequate for clinical practice. MCsquare also simulates prompt gamma emission and can thus be used also for in vivo range verification.
Iterative reconstruction for CT perfusion with a prior‐image induced hybrid nonlocal means regularization: Phantom studies
Authors: Li Bin , Lyu Qingwen , Ma Jianhua , Wang Jing
Published: March 2016

Purpose:

In computed tomography perfusion (CTP) imaging, an initial phase CT acquired with a high‐dose protocol can be used to improve the image quality of later phase CT acquired with a low‐dose protocol. For dynamic regions, signals in the later low‐dose CT may not be completely recovered if the initial CT heavily regularizes the iterative reconstruction process. The authors propose a hybrid nonlocal means (hNLM) regularization model for iterative reconstruction of low‐dose CTP to overcome the limitation of the conventional prior‐image induced penalty.

Methods:

The hybrid penalty was constructed by combining the NLM of the initial phase high‐dose CT in the stationary region and later phase low‐dose CT in the dynamic region. The stationary and dynamic regions were determined by the similarity between the initial high‐dose scan and later low‐dose scan. The similarity was defined as a Gaussian kernel‐based distance between the patch‐window of the same pixel in the two scans, and its measurement was then used to weigh the influence of the initial high‐dose CT. For regions with high similarity (e.g., stationary region), initial high‐dose CT played a dominant role for regularizing the solution. For regions with low similarity (e.g., dynamic region), the regularization relied on a low‐dose scan itself. This new hNLM penalty was incorporated into the penalized weighted least‐squares (PWLS) for CTP reconstruction. Digital and physical phantom studies were performed to evaluate the PWLS‐hNLM algorithm.

Results:

Both phantom studies showed that the PWLS‐hNLM algorithm is superior to the conventional prior‐image induced penalty term without considering the signal changes within the dynamic region. In the dynamic region of the Catphan phantom, the reconstruction error measured by root mean square error was reduced by 42.9% in PWLS‐hNLM reconstructed image.

Conclusions:

The PWLS‐hNLM algorithm can effectively use the initial high‐dose CT to reconstruct low‐dose CTP in the stationary region while reducing its influence in the dynamic region.
Indoor Microgravity Survey
Authors: Secco Richard A. , Sukara Reynold E.
Published: March 2016

There are many lab exercises for upper-level school students and freshman undergraduates to measure the value of the local acceleration due to gravity (g) near Earth's surface. In these exercises, the value of g is usually taken to be constant. The approach is often based on measuring the period of a pendulum that is inversely proportional to the square root of g. Traditional measurements of the period of a simple or inclined pendulum involve use of a stopwatch to measure the time required to complete a number of oscillations, but other more sophisticated measurement techniques for greater accuracy, such as a photogate timing system, measuring the time-dependent tension on the string, or using a stepper motor connected to a conical pendulum have been described. Using video imaging, the mechanics of objects dropped from some height has also been used to determine g. In physics courses where physical principles are applied to Earth problems, however, the goal is usually to measure a change in a potential field, such as Earth's gravitational field, in order to determine anomalous subsurface characteristics. In this paper, we describe an indoor exercise to measure the local change in g resulting from a large anomalous mass near the observation location.
In Vitro
Interactions between Target of Rapamycin Kinase Inhibitor and Antifungal Agents against Aspergillus Species
Authors: Gao Lujuan , Ding Xiaozhen , Liu Zhun , Wu Qingzhi , Zeng Tongxiang , Sun Yi
Published: March 2016

In vitro
interactions of INK128, a target of rapamycin (TOR) kinase inhibitor, and antifungals, including itraconazole, voriconazole, posaconazole, amphotericin B, and caspofungin, against
Aspergillus
spp. were assessed with the broth microdilution checkerboard technique. Our results suggested synergistic effects between INK128 and all azoles tested, against multiple
Aspergillus fumigatus
and
Aspergillus flavus
isolates. However, no synergistic effects were observed when INK128 was combined with amphotericin B or caspofungin. No antagonism was observed for any combination.
‘A problematic plum pit in the piping’: a case of traumatic oesophageal perforation
Authors: Ibrahim Nader , Chauhan Ishaan , Nikkar-Esfahani Ali
Published: March 2016

A 75-year-old man presented to accident and emergency having swallowed a plum pit. He initially experienced sharp neck pain, which was mild at presentation. He was otherwise haemodynamically stable and was able to subsequently eat a sandwich without consequence.

He was referred to the ear, nose and throat senior house office (SHO), who reviewed the soft tissue radiograph, which appeared normal. The patient displayed no concerning clinical signs and was well; however, his pain persisted. Examination revealed a localised area of surgical emphysema on the left side of the neck. Retrospective review of the soft tissue radiograph showed a small region of subcutaneous free air. An urgent CT scan confirmed a pneumomediastinum indicative of an oesophageal perforation. The patient was admitted for observation, and was managed conservatively without surgical intervention. He was weaned onto sterile fluid and progressed to a solid diet. He was discharged from hospital with no long-term sequelae.
Posterior C1-C2 calcium pyrophosphate dihydrate crystal deposition disease
Authors: Ng Isaac Bing-Yi , Arkun Knarik , Riesenburger Ron I
Published: March 2016

Calcium pyrophosphate dihydrate (CPPD) crystal deposition disease rarely occurs in the posterior aspect of the craniocervical junction (CCJ). To the best of our knowledge, there have been only 2 previously reported cases of patients with posterior CPPD lesions in this region that have led to cervical myelopathy. We report the case of a 70-year-old man presenting with neck pain and cervical myelopathy with multilevel stenosis from C1-C6. The stenosis was worst at C1-C2, secondary to compression by a CPPD lesion posterior to the spinal cord. The patient underwent a C2-C6 laminectomy and fusion with resection of the CPPD lesion. In this report, we discuss the patient and present a novel theory to explain the preponderance of CPPD lesions in the CCJ occurring anteriorly and not posteriorly to the spinal cord.
SO(10) grand unification in light of recent LHC searches and colored scalars at the TeV-scale
Authors: Aydemir Ufuk
Published: March 2016

We analyze the compatibility of the recent LHC signals and the TeV-scale left–right model(s) in the minimal nonsupersymmetric SO(10) framework. We show that the models in which the Higgs content is selected based on the extended survival hypothesis do not allow the [Formula: see text] boson to be at the TeV-scale. By relaxing this conjecture, we investigate various scenarios where a number of colored-scalars, originated from various Pati–Salam multiplets, are light and whence they survive down to the low energies. Performing a detailed renormalization group analysis with various low-energy Higgs configurations and symmetry breaking chains, while keeping the high energy Higgs content unmodified; we find that, among a number of possibilities, the models which have a light color-triplet scalar, and its combination with a light color-sextet, particularly stand out. Although these models do allow a TeV-scale [Formula: see text] boson, generating the required value of the gauge coupling [Formula: see text] at this scale is nontrivial.
A model of social network formation under the impact of structural balance
Authors: Li Pei , Cheng Jiajun , Chen Yingwen , Wang Hui
Published: March 2016

Social networks have attracted remarkable attention from both academic and industrial societies and it is of great importance to understand the formation of social networks. However, most existing research cannot be applied directly to investigate social networks, where relationships are heterogeneous and structural balance is a common phenomenon. In this paper, we take both positive and negative relationships into consideration and propose a model to characterize the process of social network formation under the impact of structural balance. In this model, a new node first establishes a link with an existing node and then tries to connect to each of the newly connected node’s neighbors. If a new link is established, the type of this link is determined by structural balance. Then we analyze the degree distribution of the generated network theoretically, and estimate the fractions of positive and negative links. All analysis results are verified by simulations. These results are of importance to understand the formation of social networks, and the model can be easily extended to consider more realistic situations.
Modeling the curvature and interface shear stress of GaN-sapphire system
Authors: Li Jia , Shi Junjie , Wu Jiejun , Liu Huizhao
Published: March 2016

The curvature and interface shear stress of GaN-sapphire system are studied by establishing the mechanical equations based on two main assumptions: (a) the thickness of GaN film can be compared to the thickness of sapphire substrate, and (b) the thickness of GaN film is non-uniform. Our results show that the curvature of GaN-sapphire system is a variable within the whole circular system. The interface shear stress changes direction around at the middle of radius for the circular system, and the curvature have an important effect on the interface shear stress due to the consideration of non-uniform thickness for GaN film.
Phenomenological analysis of breakup of 9Be nuclei into two α-particles and neutron in peripheral interactions with emulsion nuclei
Authors: Olimov Khusniddin K. , Olimov Kosim , Lugovoi V. V. , Zarubin P. I. , Lutpullaev S. L. , Olimov Alisher K. , Navotny V. Sh. , Abdurakhmanov U. U. , Artemenkov D. A. , Zarubina I. G. , Rusakova V. V. , Arif Atif , Khan Imran
Published: March 2016

Phenomenological Monte Carlo model of peripheral interactions of 9Be nuclei with emulsion nuclei at [Formula: see text][Formula: see text]GeV with formation of an excited 9Be* nucleus and its subsequent breakup, either directly or through formation of an intermediate 8Be nucleus, into two [Formula: see text]-particles and a neutron was constructed. A comparative analysis of the experimental data on angular correlations and momentum spectra of [Formula: see text]-particles, coming from a breakup event, with the Monte Carlo model calculations was made. The constructed Monte Carlo model described quite satisfactory the total momentum and transverse momentum distributions of [Formula: see text]-particles and the distribution of angles between the total momentum (as well as transverse momentum) vectors of two [Formula: see text]-particles in 9Be* nucleus breakup events in experiment. For the first time, the total momentum and transverse momentum distributions of neutrons, accompanying two [Formula: see text]-particles from 9Be* decay, in peripheral interactions of 9Be nuclei with emulsion nuclei were reconstructed using the Monte Carlo model.
Co-Production in Business Counselling in Microfinance Setting: A Conceptual Approach
Authors: Abeysekera Ruwan , Patton Dean , Mullineux Andrew
Published: March 2016

Recent developments in service literature highlight the importance of co-production between the firm and the client in order to create value. This paper presents a model of co-production within the context of microfinance provision and investigates the dyadic relationship between Counsellors from Microfinance Institutions (MFIs) and the Owner Managers of Micro and Small Enterprises (MSEs). The paper develops a conceptual model that identifies the factors that facilitate co-production between Counsellors and Owner Managers. It also identifies co-production outcomes relating to MSEs and MFIs concerned. The model offers researchers a framework for empirical studies in the microfinance setting. Furthermore, microfinance policy makers can use this model to formulate strategies that offer many benefits to both MFIs and Owner Managers.
A note on nonlinear σ-models in noncommutative geometry
Authors: Lee Hyun Ho
Published: March 2016

We study nonlinear [Formula: see text]-models defined on a noncommutative torus as a two-dimensional string worldsheet. We consider (i) a two-point space, (ii) a circle, (iii) a noncommutative torus, (iv) a classical group [Formula: see text] as examples of space-time. Based on established results, the trivial harmonic unitaries of the noncommutative chiral model known as local minima are shown not to be global minima by comparing them to the symmetric unitaries derived from instanton solutions of the noncommutative Ising model corresponding to a two-point space. In addition, a [Formula: see text]-action on field maps is introduced to a noncommutative torus, and its action on solutions of various Euler–Lagrange equations is described.
Greedy adaptive decomposition of signals based on nonlinear Fourier atoms
Authors: Kou Kit Ian , Li Hong
Published: March 2016

This paper aims at adaptive decomposition of signals in terms of nonlinear Fourier atoms. Each nonlinear Fourier atom is analytic and mono-component. The algorithm is considered as an adaptive greedy procedure based on nonlinear Fourier atoms. The convergence results for the proposed algorithms show that it is suitable to approximate a signal by a linear combinations of nonlinear Fourier atoms. Experiments are presented to illustrate the proposed algorithm and theory.
Technological Change of the Innovation Payment System
Authors: Wonglimpiyarat Jarunee
Published: March 2016

This paper explores the process of technological change in the payment system. In particular, the study aims to gain understanding if Bitcoin would bring about a paradigmatic shift toward a cashless society. The analysis is based on the technology S-curve and Schumpeter’s model of economic development. It is interesting to see that the swing of S-curves is not strong enough to cause a paradigm shift according to the Schumpeterian concept of creative destruction. The study also compares Bitcoin with PayPal, a similar digital currency and major online payment system, to gain insights of the new challenge toward a cashless economy. The parallel S-curve trajectories of electronic money innovations signify a move from a cash-based economy toward a less cash society.
Public Participation in China: Strengths, Weaknesses, and Lessons Learned
Authors: Enserink Bert , Alberton Mariachiara
Published: March 2016

Public participation is an integral part of the Chinese environmental impact assessment (EIA) system. Successful public participation though is more than just granting a right to participate and setting out a procedure in a legislative act. This paper analyses the strengths and weaknesses of the Chinese EIA system by reporting on the practical issues and lessons learned during regional workshops with EIA professionals in China. It offers an overview of principles, legal instruments, mechanisms and guidelines, and analyses the Chinese practices at the provincial and local level. Recommendations to improve public participation in China are based on a gap analysis, best practices and lessons learned, interviews with key stakeholders, inputs from public authorities, EIA agencies, and civil society organisations, collected in training modules and public events held in Yunnan, Shandong and Beijing.
Stable dielectric response of low-loss aromatic polythiourea thin films on Pt/SiO2 substrate
Authors: Eršte A. , Fulanović L. , Čoga L. , Lin M. , Thakur Y. , Zhang Q. M. , Bobnar V.
Published: March 2016

We have investigated dielectric properties of aromatic polythiourea (ArPTU, a polar polymer containing high dipolar moments with very low defect levels) thin films that were developed on Pt/SiO2 substrate. The detected response is compared to the response of commercially available polymers, such as high density polyethylene (HDPE) and polypropylene (PP), which are at present used in foil capacitors. Stable values of the dielectric constant [Formula: see text] (being twice higher than in HDPE and PP) over broad temperature and frequency ranges and dielectric losses as low as in commercial systems suggest ArPTU as a promising candidate for future use in a variety of applications.
Coherent population trapping in small- and chip-scale 87Rb vapor cells with buffer gas
Authors: Ermak S. V. , Semenov V. V. , Petrenko M. V. , Pyatyshev E. N.
Published: March 2016

The characteristics of coherent population trapping (CPT) signal were investigated in small-size glass vapor cells containing [Formula: see text]Rb and Ne buffer gas with narrow line-width laser pumping on D2 line. The parameters of CPT signals were measured using small-size vapor cells with Ne buffer gas pressure in the range of 200–400 Torr, cell temperature in the range of 65–120 [Formula: see text]C and the values of laser pumping power of 30–400 [Formula: see text]W/cm2. Optimal conditions, under which the minimal value of short-term instability of resonance line is achieved, were obtained in experiments. Orientation frequency shifts of CPT resonance using glass [Formula: see text]Rb vapor cells containing buffer gas and anti-relaxation coating were compared. CPT signals using vapor cells based on integrated technologies containing [Formula: see text]Rb in atmosphere of Ne were also investigated. The CPT signals with typical line widths of 2–3 kHz and signal-to-noise ratio of 1500 in 1 Hz bandwidth are observed, which allows one to provide relative frequency instability of 10[Formula: see text] at 100 s.
Illustrating Timing Drift
Authors: Levy David C.
Published: March 2016

This letter illustrates the effect of timing drift using a short Ada program as an educational tool.
An Error in the Ada Universal Arithmetic Package
Authors: Froggatt Terry
Published: March 2016

An Ada Universal Arithmetic package was published over three decades ago in Ada Letters. It was incorporated into several Ada compilers, and it is one of the few compiler components which will have required no change as the Ada language has evolved. The purpose if this note is to draw attention to an error in that package, which may or may not have been corrected in the compilers, but which has never subsequently been corrected within Ada Letters.
Reusable Software Components
Authors: Levine Trudy
Published: March 2016

In celebration of the 200th anniversary of the birth of Ada Lovelace, this column contains a listing of reusable software components, begun for Ada Letters in 1990.

All information is obtained directly from parties affiliated with web sites hosting Ada components or from the sites themselves. As always, no recommendations or guarantees are implied. We appreciate comments, corrections, and suggestions from our readers.
The Rapid Emergence of High Level Gentamicin Resistance in Enterococci
Authors: Forward Kevin R , Kennedy James K , Degagne Patricia A , Bartlett Kathy R , Harding Godfrey KM
Published: March 2016

The proportion of enterococci isolated from blood and urine cultures that were highly resistant to gentamicin and streptomycin were determined. No blood or urine isolates highly resistant to gentamicin were seen in 1983, whereas by 1986–87 25% of blood and 17% of urine isolates were highly resistant. The rapid emergence of gentamicin resistance has serious implications for patients with life threatening enterococcal disease.
The Isolation Rate of Escherichia coli 0157:H7 in Toronto and Surrounding Communities
Authors: Simor Andrew E , Watt Christine , Low Donald E
Published: March 2016

Verocytotoxin‐producing strains of Escherichia coli, most often serotype 0157:H7, have been associated with both sporadic and epidemic diarrheal disease in Canada. In order to determine the isolation rate of E coli 0157:H7 in outpatients with diarrhea, all stool specimens submitted for culture to Med‐Chem Laboratories in Metropolitan Toronto between June 1988 and September 1989 were cultured on MacConkey‐Sorbitol agar in addition to standard enteric media. A total of 46 (0.3%) of 16,125 stool specimens yielded E coli 0157:H7 or verotoxin‐producing E coli 0157:H−. These isolates came from 31 patients with diarrhea; only 16 (52%) had a history of hemorrhagic colitis and one patient developed hemolytic uremic syndrome. Although MacConkey‐Sorbitol agar was useful as a differential medium for detecting E coli 0157:H7, 14.5% of all specimens yielded nonsorbitol‐fermenting isolates. It is not certain whether the routine use of MacConkey‐Sorbitol agar is justified when isolation rates of E coli 0157:117 are very low.
Use of Ganciclovir in the Treatment of Acquired Cytomegalovirus Disease in a Preterm Infant
Authors: Amin H , Jadavji T , Sauve R , Gill J
Published: March 2016

The first use of ganciclovir in a preterm infant is reported. The 27 week appropriate‐for‐gestational‐age male infant developed a disseminated cytomegalovirus infection subsequent to a blood transfusion. A daily dose of 10 mg/kg administered intravenously in two divided doses for a total of 14 days was given without adverse clinical or toxic effects. The patient has remained well following discharge from hospital.
Field Studies on Lyme Disease in North America
Authors: Piesman Joseph
Published: March 2016

The primary tick vector of Borrelia burgdorferi in eastern and central North America is Ixodes dammini; in western North America, Ixodes pacificus. Searching for the appropriate vector is the first step in determining whether a region is endemic and enzootic for the spirochete B burgdorferi, the etiological agent of Lyme disease, followed by examination of the ticks (questing or already attached to hosts) and wildlife for the spirochete. Questing ticks can be collected through a variety of methods. The two major animal hosts for I dammini are the white‐footed mouse Peromyscus leucopus and the white‐tailed deer Odocoileus virginianus. Sampling strategies should consider habitat and season. All three life stages of the vector tick should be located, indicating a self‐sustaining population. Although B burgdorferi can be detected in many ways, there is no substitute for isolating the spirochete in Barbour‐Stoenner‐Kelly II medium for definitive proof of the presence of the Lyme disease spirochete.
Bacteremia due to Helicobacter cinaedi in Two Patients with Human Immunodeficinecy Virus Infection
Authors: Simor Andrew E , Brunton James L
Published: March 2016

Helicobacter cinaedi (formerly Campylobacter cinaedi) has been associated with enteric disease in homosexual men. The authors report two cases of H cinaedi bacteremia occurring in patients with human immunodeficiency virus (HIV) infection. These cases illustrate that H cinaedi may act as an opportunistic pathogen in patients with HN infection or the acquired immune deficiency syndrome.