bluuebunny/crossref_metadata_2025 huggingface dataset:
A systematic video analysis of National Hockey League (NHL) concussions, part II: how concussions occur in the NHL
Authors: Hutchison Michael G , Comper Paul , Meeuwisse Willem H , Echemendia Ruben J
Published: May 2013

Background

Concussions in sports are a growing cause of concern, as these injuries can have debilitating short-term effects and little is known about the potential long-term consequences. This work aims to describehowconcussions occur in the National Hockey League.

Methods

Case series of medically diagnosed concussions for regular season games over a 3.5-year period during the 2006–2010 seasons. Digital video records were coded and analysed using a standardised protocol.

Results

88% (n=174/197) of concussions involved player-to-opponent contact. 16 diagnosed concussions were a result of fighting. Of the 158 concussions that involved player-to-opponent body contact, the most common mechanisms were direct contact to the head initiated by the shoulder 42% of the time (n=66/158), by the elbow 15% (n=24/158) and by gloves in 5% of cases (n=8/158). When the results of anatomical location are combined with initial contact, almost half of these events (n=74/158) were classified as direct contact to the lateral aspect of the head.

Conclusions

The predominant mechanism of concussion was consistently characterised by player-to-opponent contact, typically directed to the head by the shoulder, elbow or gloves. Also, several important characteristics were apparent: (1) contact was often to the lateral aspect of the head; (2) the player who suffered a concussion was often not in possession of the puck and (3) no penalty was called on the play.
Barriers and facilitators to CPR knowledge transfer in an older population most likely to witness cardiac arrest: a theory-informed interview approach
Authors: Vaillancourt Christian , Charette Manya , Kasaboski Ann , Brehaut Jamie C , Osmond Martin , Wells George A , Stiell Ian G , Grimshaw Jeremy
Published: May 2013

Background

We sought to identify perceived barriers and facilitators to cardiopulmonary resuscitation (CPR) training and performing CPR among people above the age of 55 years.

Methods

We conducted semistructured qualitative interviews with a purposive sample of independent-living individuals aged 55 years and older from urban and rural settings. We developed an interview guide based on the constructs of the Theory of Planned Behaviour, which elicits salient attitudes, social influences and control beliefs potentially influencing CPR training and performance. Interviews were recorded, transcribed verbatim and analysed until achieving data saturation. Two independent reviewers performed inductive analyses to identify emerging themes, and ranked them by way of consensus.

Results

Demographics for the 24 interviewees: mean age 71.4 years, women 58.3%, urban location 75.0%, single dwelling 58.3%, CPR training 79.2% and prior CPR on real victim 8.3%. Facilitators of CPR training included: (1) classes in a convenient location; (2) more advertisements; and (3) having a spouse. Barriers to taking CPR training included: (1) perception of physical limitations; (2) time commitment; and (3) cost. Facilitators of providing CPR included: (1) 9-1-1 CPR instructions; (2) reminders/pocket cards; and (3) frequent but brief updates. Barriers to providing CPR included: (1) physical limitations; (2) lack of confidence; and (3) ambivalence of duty to act in a large group.

Conclusions

We identified key facilitators and barriers for CPR training and performance in a purposive sample of individuals aged 55 years and older.
A survey of the opinions of recent veterinary graduates and employers regarding early career business skills
Authors: Bachynsky E. A. , Dale V. H. M. , Kinnison T. , Gazzard J. , Baillie S.
Published: May 2013

A questionnaire was designed to assess recent veterinary graduates' proficiency in early career business skills, from the perspectives of graduates of 2006–2008 and employers of recent graduates in the UK. Recent graduates perceived themselves to be generally more competent in financial matters than employers considered them to be. However, when specific skills were assessed, graduates felt less prepared than employers considered them to be competent. Overall, graduates and employers rated recent graduates' preparedness/competence as poor to average for all skills, which were regarded as having average to high importance. Both groups commented on the difficulties faced by new graduates in terms of client communication (generally and financially), and having the confidence to charge clients appropriately for veterinary services. The results of this study indicate that veterinary schools need to take a more active role in the teaching of basic finance skills in order to equip graduates with essential early career competencies. It is anticipated that the information reported will help inform undergraduate curriculum development and highlight the need for increased training at the continuing education level.
State of the art for enhancing the blast resistance of reinforced concrete columns with fiber-reinforced plastic
Authors: Crawford John E.
Published: May 2013

Protective design has become a chief concern in the design of some bridges and buildings, particularly related to the requirement that such facilities offer protection from accidental or malicious explosions. In this paper, the enhancement of the blast-resistance capability of reinforced concrete columns using FRP (fiber-reinforced plastic) is examined as a key element in upgrading the protective design of existing buildings and bridges. In this paper, the basic behaviors that need to be considered in blast effects analysis of RC columns for vehicle bomb threats are described. The ability of FRP to address these sorts of risks is shown through the analysis and test results presented. Three crucial points are made: (1) FRP offers a remarkable capability to enhance the blast resistance of existing RC columns, (2) assessing the residual capacity of large columns struck by a blast loading involves consideration of the effects of material damage, and (3) physics-based material models are often needed to capture the concrete behaviors engendered by intense blast loads.
Modeling the effects of varied forest management regimes on carbon dynamics in jack pine stands under climate change
Authors: Wang Weifeng , Peng Changhui , Kneeshaw Daniel D. , Larocque Guy R. , Lei Xiangdong , Zhu Qiuan , Song Xinzhang , Tong Queju
Published: May 2013

Climate change and its potential effects on ecosystems justify the need to implement forest management strategies that increase carbon (C) sequestration. A process-based model, TRIPLEX-Management, was used to investigate how to increase C sequestration within managed jack pine (Pinus banksiana Lamb.) forests. The simulations included a constant climate scenario and two climate change scenarios generated from the Coupled Global Climate Model (CGCM 3.1). A total of 36 forest management scenarios (a control where no forest management occurred, five varied rotation length harvesting-only regimes, and combinations of six thinning regimes and five rotation lengths) were simulated under each climate scenario for nine sites characterized by stocking levels from 0.3 to 0.7. A significant increase in C sequestration was generated under the climate change scenarios compared with those under constant climate. Mean annual net ecosystem productivity (NEP) varied with rotation length, but was not changed by precommercial thinning. Future studies should consider life cycle analysis of harvested wood products as in this study they were assumed to be a permanent C sink. Climate warming might enhance limited positive effects of forest thinning on C sequestration. Shortening rotation length from 70–80 years to 50 years might enhance NEP, increase wood production, and decrease the risk of climate change impacts on jack pine forests.
Lattice constant anomaly in the Li1+xV1–xO2 system near x = 0
Authors: Gaudet J.M. , Dahn J.R.
Published: May 2013

Polycrystalline powders of Li1+xV1–xO2 were prepared in the composition range –0.10 ≤ x ≤ 0.30 via the solid state technique. X-ray diffraction indicated single phase, layered R3̄m structure material with the exception of some impurity phases for x ≥ 0.15. Analysis of powder X-ray diffraction patterns revealed an anomaly in the lattice parameters centered near x = 0. The c-axis of the hexagonal representation was at a maximum for this composition and the a-axis at a minimum. Careful X-ray diffraction scans observed the well-known superlattice peak, which is due to trimer formation in LiVO2 — a periodic lattice distortion within the plane of vanadium cations. Integrating the areas of the Li1+xV1–xO2 superlattice peaks revealed a strong correlation between composition, fraction of vanadium in the V3+ oxidation state, lattice parameter, and degree of trimer formation. These results may suggest the view of trimer formation as a consequence of vanadium t2g orbital ordering.
EMPIRICAL ANALYSIS OF THE CLUSTERING COEFFICIENT IN THE USER-OBJECT BIPARTITE NETWORKS
Authors: LIU JIANGUO , HOU LEI , ZHANG YI-LU , SONG WEN-JUN , PAN XUE
Published: May 2013

The clustering coefficient of the bipartite network, C4, has been widely used to investigate the statistical properties of the user-object systems. In this paper, we empirically analyze the evolution patterns of C4 for a nine year MovieLens data set, where C4 is used to describe the diversity of the user interest. First, we divide the MovieLens data set into fractions according to the time intervals and calculate C4 of each fraction. The empirical results show that, the diversity of the user interest changes periodically with a round of one year, which reaches the smallest value in spring, then increases to the maximum value in autumn and begins to decrease in winter. Furthermore, a null model is proposed to compare with the empirical results, which is constructed in the following way. Each user selects each object with a turnable probability p, and the numbers of users and objects are equal to that of the real MovieLens data set. The comparison result indicates that the user activity has greatly influenced the structure of the user-object bipartite network, and users with the same degree information may have two totally different clustering coefficients. On the other hand, the same clustering coefficient also corresponds to different degrees. Therefore, we need to take the clustering coefficient into consideration together with the degree information when describing the user selection activity.
LIVING IN CURVED MOMENTUM SPACE
Authors: KOWALSKI-GLIKMAN JERZY
Published: May 2013

In this paper, we review some aspects of relativistic particles' mechanics in the case of a nontrivial geometry of momentum space. We start by showing how the curved momentum space arises in the theory of gravity in 2+1 dimensions coupled to particles, when (topological) degrees of freedom of gravity are solved for. We argue that there might exist a similar topological phase of quantum gravity in 3+1 dimensions. Then, we characterize the main properties of the theory of interacting particles with curved momentum space and the symmetries of the action. We discuss the space–time picture and the emergence of the principle of relative locality, according to which locality of events is not absolute but becomes observer dependent, in the controllable, relativistic way. We conclude with the detailed review of the most studied κ-Poincaré framework, which corresponds to the de Sitter momentum space.
LOCALIZATION IN A STRONGLY DISORDERED SYSTEM: A PERTURBATION APPROACH
Authors: FRASCA MARCO
Published: May 2013

We prove that a strongly disordered two-dimensional system localizes with a localization length given analytically. We get a scaling law with a critical exponent ν = 1 in agreement with the Chayes criterion ν ≥ 1. The case we are considering is for off-diagonal disorder. The method we use is a perturbation approach holding in the limit of an infinitely large perturbation as recently devised and the Anderson model is considered with a Gaussian distribution of disorder. The localization length diverges when energy goes to zero with a scaling law in agreement to numerical and theoretical expectations.
AN OBSTRUCTION TO SLICING ITERATED BING DOUBLES
Authors: VAN COTT CORNELIA A.
Published: May 2013

Recent advances in understanding slicing properties of Bing doubles of knots have depended on properties of iterated covering links. We expand and refine this covering link calculus. Our main application here is a simplified proof of the following result of Cha and Kim: If the iterated Bing double of a knot K is slice, then K is algebraically slice. Further applications are included in joint work with Livingston studying 4-genera of Bing doubles. The techniques also appear in the work of Levine studying mixed Bing-Whitehead doubles.
PROSPECTS FOR USING COHERENT ELASTIC NEUTRINO-NUCLEUS SCATTERING TO MEASURE THE NUCLEAR NEUTRON FORM FACTOR
Authors: PATTON KELLY M. , MCLAUGHLIN GAIL C. , SCHOLBERG KATE
Published: May 2013

We review the prospects of using coherent elastic neutrino-nucleus scattering (CENNS) to measure the nuclear neutron form factor. The merits and limitations of several potential neutrino sources are discussed. The effects of detector shape uncertainty and detector size on a measurement of the neutron RMS radius are also considered. We find that the detector spectral shape uncertainty is the important limiting factor on a measurement of the neutron RMS radius. In order to measure the neutron RMS radius to 5%, the spectral shape uncertainty of the detector needs to be known to 1% or better.
MONOTONICITY OF PRICES IN HESTON MODEL
Authors: OULD ALY S. M.
Published: May 2013

In this article, we study the price monotonicity in the parameters of the Heston model for a contract with a convex pay-off function; in particular we consider European put options. We show that the price is increasing in the constant term in the drift of the variance process and decreasing in the coefficient of the linear term in the drift of variance process. We also show that the price is increasing in the correlation for small values of the stock and decreasing for the large values.
INFLUENCE OF A VOLUMETRIC CHEMICAL REACTION ON THE CONVECTIVE MASS TRANSFER NEAR A DROP
Authors: AKHMETOV RUSTYAM , KUTLUEV RUSLAN
Published: May 2013

The problem of steady convective mass transfer between a spherical drop and a flow with distributed chemical reaction is considered. It is investigated in case where both Peclet number and the rate constant of the chemical reaction tend to infinity. The quantity of rate constant of the chemical reaction and Peclet number is assumed to have a constant value. It is a boundary value problem for a quasilinear partial elliptical equation with a small parameter multiplying in higher derivatives. In the neighborhood of the saddle point the additional boundary layer arises. The asymptotics of solution is constructed in the neighborhood of the saddle point. The leading term of the asymptotic expansion of solution is constructed in the boundary layer near the rear stagnation point of the drop as the solution for the quasilinear ordinary differential equation.
MODELING AND ANALYSIS OF THERMAL PROCESSES IN MECHANICAL FRICTION CLUTCH — NUMERICAL AND EXPERIMENTAL INVESTIGATIONS
Authors: AWREJCEWICZ JAN , GRZELCZYK DARIUSZ
Published: May 2013

Thermal processes occurring in the mechanical clutch or brake systems have a great influence on the strength of elements of these systems as well as on their dynamics. The contact problems exhibited by such systems include heat generated by dry friction contact surfaces. The contact dynamics in general depends on many system parameters, and it attracted attention of many researches focused on analysis of the mentioned phenomena in different kinds of mechanical systems like clutches, brakes, and others. In this work a mathematical model describing the processes of heat generation and its propagation in the mechanical friction clutch is presented. The presented model takes into account the unequal distribution of flux density of produced heat in the clutch, the thermal conductivity of materials of friction linings, and the heat transfer between the friction linings of clutch and its environments. The analyzed object is described by a set of algebraic linear homo- and heterogeneous equations, and it is derived using a computer numerical method. Many interesting numerical and experimental results are obtained, illustrated and discussed. Presented numerical results coincide with experimental data.
THE DYNAMICS OF THE FOREST CRANE DURING THE LOAD CARRYING
Authors: POSIADALA BOGDAN , WARYS PAWEL , CEKUS DAWID , TOMALA MATEUSZ
Published: May 2013

In this paper, the theoretical and calculation model of the forest crane and the lifted load is presented. The model enables the simulation of the motion of the load carried by a forest crane while taking into account the elastic deformations of the boom. The lifted load has been modeled as a 3D rigid body. The application of such a load model enables the simplification and enhancement of the calculation algorithm. The equations describing the coupled motion of the system load and machine elements are presented. The kinematic model enables the analysis of the basic motion of the load as a response of the system to operational control of the forest crane. In order to determine the motion parameters it was assumed that all system elements are rigid. The lifted load is also treated as a rigid body and its motion is the result of the movement of the load suspension point and the dynamic interactions generated during the motion of the system. The presented sample results from the numerical calculations were obtained from the Matlab system. The initial problem has been solved by the Runge–Kutta method. The numerical program has been developed on the basis of the presented model which allows analyzing the motion of load arising from crane operating mechanisms.
HOW CAN SOCIAL HERDING ENHANCE COOPERATION?
Authors: SCHWEITZER FRANK , MAVRODIEV PAVLIN , TESSONE CLAUDIO J.
Published: May 2013

We study a system in which N agents have to decide between two strategies θi(i ∈ 1 … N), for defection or cooperation, when interacting with other n agents (either spatial neighbors or randomly chosen ones). After each round, they update their strategy responding nonlinearly to two different information sources: (i) the payoff ai(θi, fi) received from the strategic interaction with their n counterparts, (ii) the fraction fi of cooperators in this interaction. For the latter response, we assume social herding, i.e., agents adopt their strategy based on the frequencies of the different strategies in their neighborhood, without taking into account the consequences of this decision. We note that fi already determines the payoff, so there is no additional information assumed. A parameter ζ defines to what level agents take the two different information sources into account. For the strategic interaction, we assume a Prisoner's Dilemma game, i.e., one in which defection is the evolutionary stable strategy. However, if the additional dimension of social herding is taken into account, we find instead a stable outcome where cooperators are the majority. By means of agent-based computer simulations and analytical investigations, we evaluate the critical conditions for this transition toward cooperation. We find that, in addition to a high degree of social herding, there has to be a nonlinear response to the fraction of cooperators. We argue that the transition to cooperation in our model is based on less information, i.e., on agents which are not informed about the payoff matrix, and therefore rely on just observing the strategy of others, to adopt it. By designing the right mechanisms to respond to this information, the transition to cooperation can be remarkably enhanced. Our results are obtained in an evolutionary PD game with fixed payoffs and a fixed four-player neighborhood, where agents follow a stochastic better response dynamics.
(Invited) Thermal Transport in Graphene and Graphene-based Composites
Authors: Hu Jiuning , Park Wonjun , Ruan Xiulin , Chen Yong P.
Published: May 2013

We theoretically and experimentally studied the thermal transport properties in various graphene-based systems. Firstly, we review our previous works of molecular dynamics simulations to study the thermal transport in graphene nanoribbons (GNRs). We also studied negative differential thermal conductance (NDTC) at large temperature biases in GNRs. We extended our study of NDTC in the diffusive limit into general one-dimensional thermal transport and found that NDTC is possible if thermal junctions are introduced. These findings are useful for future applications of controlling heat at nanoscale. Secondly, we describe our experimental work of synthesized graphene-based composites with fillers of reduced graphene oxide and polymers. We used 3ω method to measure the thermal conductivity and found that the thermal conductivity can be tuned dramatically by the graphene filler concentration. Graphene-based composites are potentially promising as thermal interface materials, which have become increasingly important in modern heat management in many industrial applications.
(Invited) Recent Advances in Graphene RF Electronics: Opportunities
Authors: Moon Jeong-sun , Gaskill D.K. , Asbeck Peter
Published: May 2013

We will present recent progress in graphene material, graphene FETs, heterostructures, graphene NEMS, and potentially disruptive RF applications of graphene FETs such as linear efficient mixers and high dynamic range radiometers. Development of emerging graphene and graphene heterostructure would potentially improve RF systems with or without integration with standard Si/III-V RFICs.
Transfer-Free Bilayer Graphene FETs: Application as Memory Devices
Authors: Wessely Pia Juliane , Schwalke Udo
Published: May 2013

In this paper we report on the application of in-situ CCVD grown bilayer graphene transistors (BiLGFETs) suitable as memory devices. By means of catalytic chemical vapor deposition (CCVD) the BiLGFETs are realized directly on oxidized silicon substrate without transfer. These BiLGFETs possess unipolar p-type device characteristics with a high on/off-current ratio between 1x105 and 1x107 at room temperature. The hysteresis of BiLGFETs depends on the cycling range of the applied backgate voltage VBG while the sub-threshold slope is uniform for varied temperatures and varied cycling ranges of the backgate voltage. Based on the observed properties of BiLGFETs it is possible to use BiLGFETS as memory devices.
(Invited) III-V/High-k Defects: DIGS vs. Border Traps
Authors: Hinkle Christopher L. , Galatage Rohit V. , Dong Hong , Anwar Sarkar R. M. , Brennan Barry , Wallace Robert M. , Vogel Eric M.
Published: May 2013

The capacitance-voltage (C-V) response of III-V MOS devices has been a subject of increased research and debate over the past decade. Attempts to correlate chemical states to the observed electrical response in addition to simulation and modeling have led to great advances in the understanding of these systems. Here, we present our observations on the electrical and physical characteristics of III-V based devices. The C-V response is fundamentally different than that of Si-based devices owing to the tunneling of charge carriers into distributed trap states. Our investigations suggest that these trap states are caused by a disordered chemical region associated with the III-V semiconductor (Disorder Induced Gap States, DIGS) and not due to defects in the high-k dielectric (border traps).
Tensor Evaluation of Stress Relaxation Profile in Strained SiGe Nanostructures on Si Substrate
Authors: Tomita Motohiro , Kosemura Daisuke , Usuda Koji , Ogura Atsushi
Published: May 2013

A strained SiGe layer will be used in next-generation transistors to improve device performance along with device scaling. However, the stress relaxation of SiGe layer may be inevitable in nanodevices, because the SiGe layer is processed into nanostructure. In this study, we evaluated the stress relaxation profiles in mesa-shaped strained SiGe layers on Si substrate by electron back scattering pattern (EBSP), super-resolution Raman spectroscopy (SRRS) measurements, and finite element method (FEM) simulation. As a result, the stress relaxation profiles with high spatial resolution were obtained by each measurement. The range of σxx stress relaxation is mostly 100 nm from edge. The drastically σxx stress relaxation was over than approximately 25 percent in that range. Thus, the stress relaxation is inevitable in nanostructure with less than 200 nm scale. Moreover, there is a good correlation between the results of EBSP, SRRS measurements, and FEM simulation. The spatial resolution of EBSP and SRRS measurements were estimated less than 100 nm. Thus, super-resolution algorithm improved the spatial resolution of Raman spectroscopy from approximately 400 nm to sub-100 nm. It is prospective to evaluate the precise stress relaxation profile the sub-100 nm order structures by EBSP and SRRS measurements, respectively. Moreover, the complement of FEM simulation is important to verify the results of EBSP and SRRS. We believe that EBSP, SRRS measurements, and FEM simulation will be indispensable to for evaluating stress in future MOSFETs with high spatial resolution, which will surely surpass the present ones in complexity.
Identification of Deep Levels Associated with Extended and Point Defects in GeSn Epitaxial Layers Using DLTs
Authors: Gupta Somya , Simoen Eddy , Vrielinck Henk , Merckling Clement , Vincent Benjamin , Gencarelli Federica , Loo Roger , Heyns Marc
Published: May 2013

Deep levels associated with extended and point defects in MOS capacitors fabricated on unintentionally doped GeSn epitaxial layers on Ge-on-Si substrates have been studied by Deep Level Transient Spectroscopy (DLTS). A 9nm layer of Al2O3 is deposited as high-k gate dielectric by Molecular Beam Epitaxy. The trap kinetics and origin of defect states is discussed. Also, it is shown that the dislocation cores in relaxed p-Ge are associated with band-like donor-like states in the lower half of forbidden band gap, and act as carrier trapping and recombination centers. In addition, slow and fast oxide interface traps are observed.
ALD HfO2 and Al2O3 as MIM Capacitor Dielectric for GaAs HBT Technology
Authors: Yota Jiro
Published: May 2013

Hafnium dioxide (HfO2) and aluminum oxide (Al2O3) films have been deposited using atomic layer deposition (ALD) method and have been evaluated and used as metal-insulator-metal (MIM) capacitor dielectric in GaAs hetero-junction bipolar transistor (HBT) technology. The results show that the capacitor with 62 nm of ALD HfO2 resulted in a capacitance density of 2.73 fF/mm2, while that with 59 nm of ALD Al2O3 resulted in a capacitance density of 1.55 fF/mm2. This capacitance density increased, when the temperature was increased from 25 to 150oC. There was no significant change in capacitance density of these ALD films, when the applied voltage was varied from -5 to +5 V and when the frequency was increased from 1 kHz to 1 MHz. The breakdown voltage of the ALD hafnium dioxide and aluminum oxide films was measured to be at 34 V and 41 V, respectively. As the temperature was increased from 25 to 150oC, the breakdown voltage of both films decreased, while the leakage current increased. These results show that both ALD HfO2 and Al2O3 are compatible with, and suitable as MIM capacitor dielectric in GaAs HBT technology and can be adjusted to meet the specific application and requirements of the GaAs devices and designs.
Charateristics of Low Temperature High Quality Silicon Oxide by Plasma Enhanced Atomic Layer Deposition with In Situ Plasma Densification Process
Authors: Kim Haiwon , Zaretskiy Sergey N. , Shin Seungwoo , Jung Wooduck , Hwang Ryong , Jeong Choonsik , Park Seongjin , Hwang Hanna , Chung Ilsub
Published: May 2013

We have researched low temperature silicon oxide (SiO2) with improved electrical properties and excellent film step-coverage. In-situ O2 plasma densification (DENSIFICATION) effect on SiO2 that has been deposited by PE-ALD at temperature (<400°C) was investigated. The wet etch rate was controllable as a function of DENSIFICAION time due to repairing of the SiO2 network defects by the oxygen radicals. Angle Resolved X-ray Photoelectron Spectroscopy (AR-XPS) analysis was carried out to observe the core-level binding energies shifts (chemical shifts) in the different SiO2 films. The characteristics of wet etch rate of high quality low temperature SiO2 demonstrated lower than high temperature LP-CVD SiO2 values. Compared to LP-CVD SiO2, PE-ALD SiO2 with DENSIFICATION showed excellent I-V characteristics with lower leakage current and similar to the thermal SiO2 carrier transport plot.
Cathodoluminescence Studies of InGaN/GaN Multiple Quantum Well Structure Grown by Metal Organic Chemical Vapor Deposition
Authors: Li Ying , Lu Frank , Ramos Frank , Stokes E. B.
Published: May 2013

Scanning Electron Microscope (SEM) - Cathodoluminescence (CL) system is applied to blue emission InGaN/GaN Multiple Quantum Well (MQW) structure grown by Metal Organic Chemical Vapor Deposition (MOCVD) to study the luminescence properties of v-pit features and surface compositional variations. Emission from MQW layer and bulk n-GaN layer beneath are captured at various electron beam voltages and show that the luminescence efficiency of latter grown MQW layer may be related to that of the former grown n-GaN layer. Emission intensity variations are observed at v-pit free areas in the CL images, and it is observed that areas with higher emission intensity always show a red shift in emission wavelength. It may therefore indicate that high resolution CL system is able to image the indium inhomogeneities formed during the epitaxial growth process in nanoscale.
Low Leakage Current GaN MIS-HEMT with SiNx Gate Insulator using N2 Plasma Treatment
Authors: Liu Shih-Chien , Wang Huan-Chung , Chang Edward Yi
Published: May 2013

In this work, an effective N2 plasma treatment for suppressing leakage current in GaN MIS-HEMT has been demonstrated. We observed an important issue of leakage current from the SiNx/GaN interface. To investigate the leakage current mechanisms, we measured the leakage current from all the possible paths in the device structure, such as gate, mesa isolation, and drain leakage. The current−voltage measurement results reveal a severe leakage path at the SiNx/GaN interface after SiNx deposited on the GaN surface without N2 plasma treatment. By using N2 plasma treatment, we succeed in suppressing the leakage current and effectively improve breakdown voltage. A significant performance improvement of GaN MIS-HEMTs with very low leakage current has been achieved through the N2 plasma treatment.
Thickness Dependent Electrical Characteristics of InAlN/GaN-On-Si MOSHEMTs with Y2O3 Gate Dielectric and Au-Free Ohmic Contact
Authors: Bera Milan Kumar , Liu Yi , Kyaw Lwin Min , Ngoo Yi Jie , Chor Eng Fong
Published: May 2013

Thickness dependent electrical properties of Y2O3 gate dielectric based metal-oxide-semiconductor high electron mobility transistors (MOSHEMTs) on In0.18Al0.82N/GaN-on-Si are reported. A Au-free Ti/Al/Ni/W (25/200/40/50 nm) ohmic contact compatible for Si fab industry has been developed, which demonstrates a contact resistance of 0.56 Ω.mm and a specific contact resistivity of 1.45×10-6 Ω.cm2, obtained after annealing at 900 oC in vacuum for 60 sec. A positive shift in threshold voltage with decreasing Y2O3 film thickness is demonstrated while an improved MOSHEMTs transconductance and maximum saturation drain current have been obtained for thicker one. Besides, Y2O3 film thickness and annealing dependent interfacial properties have been investigated.
Development of Reclaimed Pattern Sapphire Substrates Technologies for GaN-Based LEDs
Authors: Huang Shih-Yung
Published: May 2013

The behavior of thermal decomposition of GaN epilayers was studied experimentally using different flow rates of hydrogen gas at elevated temperature. The GaN decomposition reactions rise with increasing annealing temperature and gas-flow rates. The GaN epilayers is complete dissociation and has a GaO2H reactant on surface of an exposed PSS. The GaN-based LEDs epilayers was grew on reclaiming substrates after GaO2H removed successfully. The optical and electrical performances of the regrown GaN-based LEDs on reclaimed-PSS agree with that of the original LEDs.
Si-Passivation of Epitaxial SiGe: Kinetics and Impact on Morphology
Authors: Seiss Birgit , Dutartre Didier
Published: May 2013

In this work a process was developed to passivate epitaxial SiGe on Si (001) substrates by a very thin Si layer. The Si-passivation was characterized in terms of deposition kinetics and of impact on the SiGe morphology during annealing. Different passivation durations allowed determining the time-dependence of the deposited thickness. A non-linear behavior was found resulting in a non-constant growth rate which decreases rapidly during the first seconds of passivation. Concerning the morphology of annealed SiGe, we showed that it can be strongly influenced by Si-passivation. The undulations appearing due to strain relaxation decrease in amplitude with increasing passivation duration until disappearance. In contrast, the morphology observed at the pattern edge, caused by thermal rounding, was not stabilized with similar passivation and annealing conditions.
(Electronics & Photonics Division Award Presentation) Si-SiO2 Interface to High-K-Ge/III-V Interface: Passivation and Reliability
Authors: Misra D.
Published: May 2013

The Si-SiO2 interface is one of the most important semiconductor-dielectric interfaces that has been studied extensively over many decades. The understanding and control of structural and electronic properties of Si-SiO2 interfaces has provided many clues for technological advancement. The article discusses how the Si-SiO2 interface migrated through the technological landscape like plasma processing damage, hot carrier effects and negative bias temperature instability (NBTI) and subsequent passivation techniques using hydrogen to nitrogen. Introduction of high-k gate dielectrics brought significant attention to the interface between silicon and high-k dielectrics but Si-SiO2 interface continued to be important because of the presence of a SiO2-based interfacial layer. With deposition of high-k gate dielectrics high carrier mobility substrates (Ge/III-V) are currently being considered as the channel materials. To obtain a high quality interface between the high-k dielectrics and the high mobility substrates some issues like deposition process, precise selection of deposition parameters, predeposition surface treatments, appropriate passivation techniques and subsequent annealing temperatures are also outlined.
(Invited) III-V/Ge CMOS Device Technologies for High Performance Logic Applications
Authors: Takagi Shinichi , Yokoyama Masafumi , Kim Sang-Hyeon , Zhang Rui , Suzuki Rena , Taoka Noriyuki , Takenaka Mitsuru
Published: May 2013

One of the ultimate CMOS structures can be the combination of III-V nMOSFETs and Ge pMOSFETs . In order to realize III-V/Ge CMOS, common gate stack and S/D formation technologies are important. Here, an ALD Al2O3 gate insulator and Ta metal gate were used for common gate stacks for InGaAs and Ge. This is because ALD Al2O3 can provide good MOS interfaces with InGaAs as well as Ge with post ECR plasma oxidation. Also, self-align Ni-Ge and Ni-InGaAs, which can be formed simultaneously for InGaAs nMOSFETs and Ge pMOSFETs, were used as the metal source/drain (S/D) regions. By utilizing these technologies, we have demonstrated successful integration of InGaAs-OI nMOSFETs and Ge p-MOSFETs on a same wafer and their superior device performance. We have found good transistor operation in both devices. High Ion/Ioff ratio of ~1e6 was obtained for InGaAs-OI nMOSFETs. The high electron and hole mobility of 1800 and 260 cm2/Vs and the mobility enhancement against Si of 3.5× and 2.3× have been demonstrated for InGaAs-OI nMOSFETs and Ge pMOSFETs, respectively.
(Invited) A Brief Review of Doping Issues in III-V Semiconductors
Authors: Jones Kevin S , Lind Aaron G. , Hatem Chris , Moffatt Steve , Ridgeway Mark C.
Published: May 2013

A brief review of n-type doping of GaAs, InGaAs and InP using ion implantation is presented. While the diffusion of the amphoteric dopant Si is not a significant issue its activation is limited to around 1×1019/cm3. This has prompted many studies into factors that might affect dopant activation including co-implantation to force site selection, damage and amorphization effects, elevated temperature implants and capping effects. A summary of these results is discussed. With interest in using III-V materials for n-channel devices in future sub 15 nm devices there is also an increasing interest in low energy implants. This suggests the role of surface degradation upon annealing will become even more important. Recent results along these lines are presented.
Limiting Factors of Channel Mobility in III-V/Ge MOSFETs
Authors: Takagi Shinichi , Kim Sang-Hyeon , Zhang Rui , Taoka Noriyuki , Yokoyama Masafumi , Takenaka Mitsuru
Published: May 2013

MOSFETs using III-V/Ge channels have been regarded as strongly important for obtaining high current drive and low supply voltage CMOS under sub 10 nm regime. However, fundamental device physics on electrical properties of III-V/Ge MOSFETs such as mobility has not been fully clarified yet. In this paper, we address key issues for enhancing channel mobility in InGaAs/Ge MOSFETs. We have confirmed in Ge p-MOSFETs with ultrathin GeOx interfacial layers formed by plasma post oxidation that the GeOx thickness can control the peak mobility in a low Ns region. This fact is attributed to lower Dit near Ev, estimated from the S factor, in thicker GeOx. The relation between the peak mobility and the interface formation technologies is addressed. As for InGaAs nMOSFETs, we point out that the trapping of free electrons into interface states or slow states within the conduction band also significantly lowers electron mobility in InGaAs MOSFETs. As another critical factor for the electron mobility reduction, the influence of the body thickness on channel mobility is introduced. The thickness fluctuation scattering can be worse for III-V MOSFETs with lower effective mass and wider inversion-layer thickness. Thus, we have proposed MOS interface buffer channel structure, where InGaAs buffer layers sandwich InGaAs channels with higher In content. Actually, we have observed the significant mobility enhancement in the In0
.3Ga0
.7As/In0
.7Ga0
.3As/ In0
.3Ga0
.7As-OI structure over single In0
.7Ga0
.3As-OI structures.
(Invited) Commercial CMOS-Integrated RF-MEMS
Authors: Morris Art , Cunningham Shawn
Published: May 2013

RF-MEMS are an enabling technology for high performance tunable and reconfigurable communications and radar applications. In this paper, we describe the successful integration of RF-MEMS with a 0.18 µm, high voltage RF-CMOS process that is fabricated on 200 mm wafers. The RF-MEMS device is hermetically encapsulated at the wafer level at the conclusion of the process. The RF-MEMS device is a switchable capacitor arrayed to form tunable capacitor arrays that can be used in various applications such as tunable matching networks, tunable filters, tunable power amplifiers, or tunable front ends more generally. The CMOS-integrated, hermetic encapsulated RF-MEMS can be moved through any final back end of line (BEOL) packaging and assembly process to deliver flip-chip or wafer level chip scale packaged devices. The commercial CMOS-integrated RF-MEMS process and product qualification are imminent at the preparation of this paper
RACK1 interacts with filamin-A to regulate plasma membrane levels of the cystic fibrosis transmembrane conductance regulator
Authors: Smith Laura , Litman Paul , Kohli Ekta , Amick Joseph , Page Richard C. , Misra Saurav , Liedtke Carole M.
Published: May 2013

Mutations in cystic fibrosis transmembrane regulator (CFTR), a chloride channel in the apical membranes of secretory epithelial cells, underlie the fatal genetic disorder cystic fibrosis. Certain CFTR mutations, including the common mutation ΔF508-CFTR, result in greatly decreased levels of active CFTR at the apical membrane. Direct interactions between CFTR and the cytoskeletal adaptors filamin-A (FlnA) and Na+/H+ exchanger regulatory factor 1 (NHERF1) stabilize the expression and localization of CFTR at the plasma membrane. The scaffold protein receptor for activated C kinase 1 (RACK1) also stabilizes CFTR surface expression; however, RACK1 does not interact directly with CFTR and its mechanism of action is unknown. In the present study, we report that RACK1 interacts directly with FlnA in vitro and in a Calu-3 airway epithelial cell line. We mapped the interaction between RACK1 and FlnA to the WD4 and WD6 repeats of RACK1 and to a segment of the large rod domain of FlnA, consisting of immunoglobulin-like repeats 8–15. Disruption of the RACK1-FlnA interaction causes a reduction in CFTR surface levels. Our results suggest that a novel RACK1-FlnA interaction is an important regulator of CFTR surface localization.
Skeletal muscle interleukin-6 regulation in hyperthermia
Authors: Welc Steven S. , Judge Andrew R. , Clanton Thomas L.
Published: May 2013

We previously reported that IL-6 production is acutely elevated in skeletal muscles exposed to ≥41°C, but the regulatory pathways are poorly understood. The present study characterizes the heat-induced transcriptional control of IL-6 in C2C12 muscle fibers. Hyperthermia exposure (42°C for 1 h) induced transcription from an IL-6 promoter-luciferase reporter plasmid. Heat shock factor-1 (HSF-1), a principal mediator of the heat shock response, was then tested for its role in IL-6 regulation. Overexpression of a constitutively active HSF-1 construct increased basal (37°C) promoter activity, whereas overexpression of a dominant negative HSF-1 reduced IL-6 promoter activity during basal and hyperthermia conditions. Since hyperthermia also induces stress-activated protein kinase (SAPK) signaling, we tested whether mutation of a transcription site downstream of SAPK, (i.e., activator protein-1, AP-1) influences IL-6 transcription in hyperthermia. The mutation had no effect on baseline reporter activity but completely inhibited heat-induced activity. We then tested whether pharmacologically induced states of protein stress, characteristic of cellular responses to hyperthermia and known to induce SAPKs and HSF-1, would induce IL-6 production in the absence of heat. The proteasome was inhibited with MG-132 in one set of experiments, and the unfolded protein response was stimulated with dithiothreitol, thapsigargin, tunicamycin, or castanospermine in other experiments. All treatments stimulated IL-6 protein secretion in the absence of hyperthermia. These studies demonstrate that IL-6 regulation in hyperthermia is directly controlled by HSF-1 and AP-1 signaling and that the IL-6 response in C2C12 myotubes is sensitive to categories of protein stress that reflect accumulation of damaged or unfolded proteins.
Expression of lipogenic genes is upregulated in the heart with exercise training-induced but not pressure overload-induced left ventricular hypertrophy
Authors: Dobrzyn Pawel , Pyrkowska Aleksandra , Duda Monika K. , Bednarski Tomasz , Maczewski Michal , Langfort Jozef , Dobrzyn Agnieszka
Published: May 2013

Cardiac hypertrophy is accompanied by molecular remodeling that affects different cellular pathways, including fatty acid (FA) utilization. In the present study, we show that cardiac lipid metabolism is differentially regulated in response to physiological (endurance training) and pathological [abdominal aortic banding (AAB)] hypertrophic stimuli. Physiological hypertrophy was accompanied by an increased expression of lipogenic genes and the activation of sterol regulatory element-binding protein-1c and Akt signaling. Additionally, FA oxidation pathways regulated by AMP-activated protein kinase (AMPK) and peroxisome proliferator activated receptor-α (PPARα) were induced in trained hearts. Cardiac lipid content was not changed by physiological stimulation, underlining balanced lipid utilization in the trained heart. Moreover, pathological hypertrophy induced the AMPK-regulated oxidative pathway, whereas PPARα and expression of its downstream targets, i.e., acyl-CoA oxidase and carnitine palmitoyltransferase I, were not affected by AAB. In contrast, pathological hypertrophy leads to cardiac triglyceride (TG) and diacylglycerol (DAG) accumulation, although the expression of lipogenic genes and the levels of FA transport proteins (CD36 and FATP) were not changed or reduced compared with the sham group. A possible explanation for this phenomenon is a decrease in lipolysis, as evidenced by the increased content of adipose triglyceride lipase inhibitor G0S2, the increased phosphorylation of hormone-sensitive lipase at Ser565, and the decreased protein levels of DAG lipase that attenuate TG and DAG contents. The increased TG and DAG accumulation observed in AAB-induced hypertrophy might have lipotoxic effects, thereby predisposing to cardiomyopathy and heart failure in the future.
Endothelium-dependent relaxations in the aorta from K2p6.1 knockout mice
Authors: Lloyd Eric E. , Pandit Lavannya M. , Crossland Randy F. , Marrelli Sean P. , Bryan Robert M.
Published: May 2013

K 2P 6.1 or TWIK-2, a two-pore domain K channel, is an important regulator of cardiovascular function. K 2P 6.1 is highly expressed in vascular smooth muscle and endothelium. Mice (8–12 wk) lacking functional K 2P 6.1 ( K 2P 6.1−/−) are hypertensive and have enhanced vascular contractility. It is not known whether the lack of functional K 2P 6.1 in endothelium has a role in the vascular dysfunction in K 2P 6.1−/− mice. We tested the hypothesis: K 2P 6.1−/− mice have impaired endothelium-dependent relaxations. K 2P 6.1−/− mice were ∼35 mmHg more hypertensive than WT mice at both 8–12 wk (young adult) and 20–24 wk (mature mice, P < 0.01; n = 8–10). Endothelium-dependent relaxations of the thoracic aorta were evaluated by isometric myography after contraction with phenylephrine (10−6 M). Maximal ACh-dependent relaxations were increased from 65 ± 1% to 73 ± 1% in the aorta from young adult ( P < 0.01; n = 6) and from 45 ± 1% to 74 ± 1% in the aorta from mature ( P < 0.001; n = 5) K 2P 6.1−/− mice compared with K 2P 6.1+/+ littermates. However, in the aorta from young adult and mature K 2P 6.1+/+ mice, 10−5 M indomethacin, a cyclooxygenase inhibitor, increased maximal ACh relaxations to knockout levels. Enhanced relaxation was also seen with ATP, a P 2Y purinergic agonist, and A23187, a nonreceptor-based agonist in mature K 2P 6.1−/− mice. Mature adult aorta from K 2P 6.1−/− showed an attenuated ACh-mediated contraction in the presence of nitro-l-arginine methyl ester (l-NAME) and without precontraction of 0.97 mN vs. 7.5 mN in K 2P 6.1−/− and K 2P 6.1+/+ ( P < 0.001; n = 5). In summary, K 2P 6.1−/− mice, which are hypertensive, have enhanced endothelium-dependent relaxations in the aorta due to the suppression of an indomethacin-sensitive constrictor component.
Role of collecting duct renin in blood pressure regulation
Authors: Ramkumar Nirupama , Kohan Donald E.
Published: May 2013

Numerous studies indicate that renin is synthesized and secreted by the collecting duct (CD). CD-derived renin may act directly on intercalated and/or principal cells through direct interaction with prorenin receptors and/or through cleavage of proximal tubule-derived angiotensinogen to ultimately produce angiotensin II and activate AT1 receptors. Preliminary studies suggest that the net effect of CD renin would be to increase distal nephron salt reabsorption and increase blood pressure. CD renin production is markedly increased in diabetes and angiotensin II-induced hypertension, suggesting that this system may exert pathophysiological effects. In this brief review, we summarize the current literature on synthesis and regulation of CD renin and consider potential mechanisms by which it regulates blood pressure.