bluuebunny/crossref_metadata_2025 huggingface dataset:
New structure in cell puncture activities by aphid stylets: a dual‐mode EPG study
Authors: Tjallingii W. Fred , Garzo Elisa , Fereres Alberto
Published: April 2010

Intracellular punctures by aphid stylets appear as potential drop (pd) waveforms in DC electrical penetration graph (EPG) recordings. We used a dual‐EPG device that recorded in one channel the ‘full EPG’ with R‐plus emf‐components (i.e., the usual DC EPG) and concurrently in a second channel the ‘R‐EPG’ with R‐components only. The circuit of the latter channel was an optimised amplitude modulation (AM) version derived from early (before 1990) AC systems. We also made some ‘emf‐EPG’ recordings using a separate high input resistance ‘emf‐amplifier’ sensitive to emf‐components only. The intracellular pd waveforms have previously been divided into three subphases, and we aimed to distinguish and separate these subphases more accurately by the dual‐EPG recordings than with the normal full EPG only. In this study, we temporarily distinguished five subphases (α–ε), but unequivocal distinction of only a few of these appeared possible, in spite of the information coming from the two signals. The lack of clearly separable features in R‐EPG signals often provided serious difficulties in pd recognition without the concurrent full EPG, but once located, only subphase II‐2 features were clear and supported the II‐2 data from the full EPG. Consequently, we could not distinguish subphases of complete pd waveforms better with additional R‐EPG information during cell punctures by Aphis gossypii Glover (Hemiptera: Aphididae). In Brevicoryne brassicae (L.) (Hemiptera: Aphididae), however, distinguishing II‐2 subphases in the full EPG was sometimes a problem. Our detailed dual‐EPG observations showed some waveform continuity from halfway into the II‐1 subphase (start of the newly recognised subphase β) until the end of the pd, with a strong but variable emf origin. This waveform tended to overrule other subphase waveforms in B. brassicae more than in A. gossypii and Myzus persicae (Sulzer) (Hemiptera: Aphididae). Subphase waveforms in full EPGs were especially difficult to recognise when pd periods had been interrupted in a virus inoculation experiment and additional R‐EPG information could then be useful. This inoculation experiment showed again that only the first subphase (II‐1) contributes to virus (Cucumber mosaic virus) inoculation by A. gossypii. In B. brassicae, the benefit of concurrent R‐EPG information in such virus experiments is presently under further investigation. Apart from this special application to virus experiments, we do not recommend the routine use of the dual‐EPG device. Furthermore, we do not advocate the distinction of more than the previously recognised three intracellular pd subphases as a feasible option in future studies. Analysis of EPGs with concurrent R‐EPGs requires substantially more analysis work without yielding consistently useful additional insights. This confirms earlier dual‐EPG results from thrips.
Survival and growth responses of eight Everglades tree species along an experimental hydrological gradient on two tree island types
Authors: Stoffella Susana L. , Ross Michael S. , Sah Jay P. , Price Rene M. , Sullivan Pamela L. , Cline Eric A. , Scinto Leonard J.
Published: April 2010

Questions: How are the early survival and growth of seedlings of Everglades tree species planted in an experimental setting on artificial tree islands affected by hydrology and substrate type? What are the implications of these responses for broader tree island restoration efforts?

Location: Loxahatchee Impoundment Landscape Assessment (LILA), Boynton Beach, Florida, USA.

Methods: An experiment was designed to test hydrological and substrate effects on seedling growth and survivorship. Two islands – a peat and a limestone‐core island representing two major types found in the Everglades – were constructed in four macrocosms. A mixture of eight tree species was planted on each island in March of 2006 and 2007. Survival and height growth of seedlings planted in 2006 were assessed periodically during the next two and a half years.

Results: Survival and growth improved with increasing elevation on both tree island substrate types. Seedlings' survival and growth responses along a moisture gradient matched species distributions along natural hydrological gradients in the Everglades. The effect of substrate on seedling performance showed higher survival of most species on the limestone tree islands, and faster growth on their peat‐based counterparts.

Conclusions: The present results could have profound implications for restoration of forests on existing landforms and artificial creation of tree islands. Knowledge of species tolerance to flooding and responses to different edaphic conditions present in wetlands is important in selecting suitable species to plant on restored tree islands
Knowing God by reason alone: what Vatican I never said
Authors: Kerr Fergus
Published: April 2010

While the First Vatican Council (1869–70) decreed that for Catholics it is a dogma of faith that we can have certain knowledge of God by the natural light of reason it was only in the Anti-Modernist Oath (1910) that this knowledge was defined as rationally demonstrable by cosmological arguments.
Protein–protein interactions and selection: generation of molecule‐binding proteins on the basis of tertiary structural information
Authors: Umetsu Mitsuo , Nakanishi Takeshi , Asano Ryutaro , Hattori Takamitsu , Kumagai Izumi
Published: April 2010

Antibodies and their fragments are attractive binding proteins because their high binding strength is generated by several hypervariable loop regions, and because high‐quality libraries can be prepared from the vast gene clusters expressed by mammalian lymphocytes. Recent explorations of new genome sequences and protein structures have revealed various small, nonantibody scaffold proteins. Accurate structural descriptions of protein–protein interactions based on X‐ray and NMR analyses allow us to generate binding proteins by using grafting and library techniques. Here, we review approaches for generating binding proteins from small scaffold proteins on the basis of tertiary structural information. Identification of binding sites from visualized tertiary structures supports the transfer of function by peptide grafting. The local library approach is advantageous as a go‐between technique for grafted foreign peptide sequences and small scaffold proteins. The identification of binding sites also supports the construction of efficient libraries with a low probability of denatured variants, and, in combination with the design for library diversity, opens the way to increasing library density and randomized sequence lengths without decreasing density. Detailed tertiary structural analyses of protein–protein complexes allow accurate description of epitope locations to enable the design of and screening for multispecific, high‐affinity proteins recognizing multiple epitopes in target molecules.
MicroRNAs and the regulation of fibrosis
Authors: Jiang Xiaoying , Tsitsiou Eleni , Herrick Sarah E. , Lindsay Mark A.
Published: April 2010

MicroRNAs (miRNAs) are small, noncoding RNAs of 18–25 nucleotides that are generally believed to either block the translation or induce the degradation of target mRNA. miRNAs have been shown to play fundamental roles in diverse biological and pathological processes, including cell proliferation, differentiation, apoptosis and carcinogenesis. Fibrosis results from an imbalance in the turnover of extracellular matrix molecules and is a highly debilitating process that can eventually lead to organ dysfunction. A growing body of evidence suggests that miRNAs participate in the fibrotic process in a number of organs including the heart, kidney, liver and lung. In this review, we summarize our current understanding of the role of miRNAs in the development of tissue fibrosis and their potential as novel drug targets.
Continuing Medical Education: Urogenital Complaints and Female Sexual Dysfunction (Part 1) (CME)
Authors: Wehbe Salim A. , Whitmore Kristene , Kellogg-Spadt Susan
Published: April 2010

Introduction

Sexual dysfunction and dyspareunia are common complaints in women with urological disorders.

Aim

To provide a comprehensive review of sexual dysfunction related to common hypersensitive/hyperactive urogenital disorders including interstitial cystitis/painful bladder syndrome (IC/PBS), overactive bladder (OAB) with and without incontinence, and high-tone pelvic floor muscle dysfunction and the appropriate treatment strategies.

Methods

A medical literature search using several related terms including sexual dysfunction, dyspareunia, IC/PBS, OAB, urinary incontinence pelvic floor dysfunction, and levator ani muscle spasm.

Main Outcome Measures

Review of the medical literature to identify relation between sexual dysfunction and common urological disorders in women and to describe appropriate treatment strategies to improve the women’s quality of life.

Results

A thorough review of sexual dysfunction in urological disorders and their related treatments modalities including: behavioral, pharmacological, and nonpharmacological therapies.

Conclusions

Sexual dysfunction is a common, underestimated, and untreated complaint in women with urologic disorders. Identifying sexual complaints and treating the underlying etiologies can result in significant improvement in a woman’s quality of life. This process requires a focused, multidisciplinary approach tailored to meet the needs of women with urogenital complaints.
A cost‐effective, simple and high‐throughput method for DNA extraction from insects
Authors: Lagisz Malgorzata , Port Gordon , Wolff Kirsten
Published: April 2010

Abstract  We present a high‐throughput cost‐effective method to extract DNA suitable for polymerase chain reaction (PCR) from insect tissue. The method uses standard 200 μL‐deep 96‐well plates in which samples are ground, digested and subsequently purified. The test extraction using four different insect species and controlling for potential contamination showed that the method yields good‐quantity and quality DNA. PCR with mitochondrial and nuclear primers was reliable. The proposed extraction protocol combines the speed of commercial 96‐well plate methods with the economies associated with readily available and cheap laboratory chemicals, consumables and equipment. Therefore, this method is particularly suitable for low‐budget research projects and for laboratories with only basic equipment present.
Toleration
Authors: Haefeli Evan
Published: April 2010

Toleration has become a much discussed and studied topic in recent years, revealing a new degree of ambivalence about its meaning and significance. This essay explores how toleration is being studied and suggests the difficulties and limitations involved in approaching this dynamic topic as a stable, consistent idea. It concludes by suggesting that there is no perfect or single ideal of toleration. Rather, toleration involves a variety of relationships across time and space in which different groups benefit (or do not) in different ways. The ambivalence reflects a developing awareness of this complicated character of toleration.
Prognostic Value of Subdivisions of Nighttime Blood Pressure Fall in Hypertensives Followed Up for 8.2 Years. Does Nondipping Classification Need to Be Redefined?
Authors: Bastos José Mesquita , Bertoquini Susana , Polónia Jorge
Published: April 2010

J Clin Hypertens(Greenwich). 2010;12:508–515. © 2010 Wiley Periodicals, Inc.

To evaluate the long‐term prognostic significance of different ranges of the percentage fall in nighttime blood pressure (BP) of the nondipping pattern, 1200 hypertensive patients (645 women, age 51±12 years) underwent ambulatory BP monitoring under stabilized therapy. The occurrence of cardiovascular (CV) events was followed for 9833 patient‐years and analyzed by the Cox hazard model. There were 152 CV fatal/nonfatal events (79 strokes, 51 coronary events, 22 others) during the 15.2 years of follow‐up. According to nighttime BP fall (%) the authors noted: <0% (reverse‐dippers [RD], n=83); 0%–4.9% (nondippers 1 [ND1], n=207); 5%–9.9% (nondippers 2 [ND2], n=311), 10%–19.9% (dippers [D], n=523); and ≥20% (extreme dippers [ED], n=76). After adjustment for confounding variables, hazard ratios (95% confidence interval) of CV event and stroke in RD vs D were 2.29 (1.31–3.99) and 2.46 (1.11–5.49); of ND1 vs D were 1.42 (1.12–1.79) and 1.62 (1.17–2.23); and of ND1 vs ND2 were 2.24 (1.33–3.75) and 2.30 (1.15–4.58). No differences were found in RD vs ND1 and ND2 vs D. Nondippers have a higher CV risk than dippers but only for a nighttime BP fall <5% suggesting that the limits for nondipping should be redefined for a stratification of CV risk.
The Association Between C‐Reactive Protein Levels and Insulin Therapy in Obese vs Nonobese Veterans With Type 2 Diabetes Mellitus
Authors: Khatana Sameed Ahmed M. , Taveira Tracey H. , Dooley Andrea G. , Wu Wen‐Chih
Published: April 2010

J Clin Hypertens (Greenwich). 2010;12:462–468. ©2010 Wiley Periodicals, Inc.

The authors studied the association between insulin use and C‐reactive protein (CRP) levels in obese (body mass index ≥30 kg/m2) and nonobese (body mass index <30 kg/m2) patients with type 2 diabetes at the Providence Veterans Affairs Medical Center. There were 64 nonobese participants (insulin use and average daily dose, 23.4% and 7.0±18.2 units at baseline and 27.1% and 9.3±21.0 units at follow‐up, respectively) and 106 obese participants (insulin use and daily dose, 39.6% and 28.2±47.3 units at baseline and 43.0% and 28.7±47.7 units at follow‐up, respectively). Both use and daily dose of insulin were modeled with CRP levels of participants upon discharge from an intensive cardiac risk management clinic and at a 1‐year follow‐up visit using a linear mixed effects model for repeated measures. There was a significant direct association between log CRP and both insulin use and daily dose for nonobese participants (β=0.3, P=.03 and β=0.01, P=.02, respectively) but not for obese participants (P=.8 and P=.5, respectively). Due to the association between insulin therapy and CRP in nonobese patients, these results may aid clinicians in deciding on the initiation of insulin therapy for nonobese diabetic patients when noninsulin alternatives are available.
Coenzyme Q10 prevents human lens epithelial cells from light‐induced apoptotic cell death by reducing oxidative stress and stabilizing BAX / Bcl‐2 ratio
Authors: Kernt Marcus , Hirneiss Christoph , Neubauer Aljoscha S. , Ulbig Michael W. , Kampik Anselm
Published: April 2010

Background:  Cataract is one of the most prevalent eye disease and a major cause for legal blindness in the world. Beside others, cumulative light‐exposure and apoptotic cell death are significantly associated with cataract development. In contrast, supplementation with antioxidants has been suggested to prevent premature cataractogenesis. This study investigates possible protective effects of Coenzyme Q10 (CoQ10) regarding light‐induced stress and apoptotic cell death in human lens epithelial cells (LEC).

Methods:  Human LEC were either pre‐incubated with CoQ10 or not and then exposed to white light. After 10–40 min of irradiation viability, induction of intracellular reactive oxygen species (ROS), apoptosis and cell death was determined. Expression of apoptotic BAX and anti‐apoptotic Bcl‐2 protein and their mRNA were determined by RT‐PCR and Western blot analysis.

Results:  Light exposure decreased LEC viability and Bcl‐2 expression and increased intracellular ROS, apoptotic cell death, and BAX expression in a time‐of‐irradiation‐dependent manner. Phototoxic cell death and apoptosis, as well as decrease of Bcl‐2 and increase in BAX expression was significantly reduced, when cells were pre‐incubated with CoQ10.

Conclusions:  In this study, CoQ10 significantly reduced light‐induced LEC‐damage and attenuated phototoxic effects on BAX and Bcl‐2 expression. Therefore, CoQ10 supplementation might also be useful in preventing LEC death and consecutive cataract formation in vivo.
Assessment of the safety of Qin Kai Ling injection: a systematic review
Authors: Hao Yuan , Kong Xiangyu , Wu Taixiang
Published: April 2010

Objective Qin Kai Ling (QKL) injection, which is based upon the traditional Chinese medicine formulation ‘An Gong Niu Huang Wan’, is widely used in treatment of many diseases. This review aims to assess the safety of QKL.

Methods We searched Chinese databases CNKI and VIP for articles published between January 1987 and April 2009.

Results A total of 1486 cases were included in this review. We were unable to determine the frequency of ADR/AE induced by QKL due to the lack of complete production and market information. We estimate, based on the limited data, that the risk of ADR/AE from QKL use should be low. We found some ADR/AE may have been induced by incorrect use of QKL, such as use in infants, or use with incompatible drugs, and some places may not suite for use of QKL, for example, four of seven patients died in private clinics or patient's home. We unable to distinguish whether incidents were ADRs or AEs because the poor reports.

Conclusion Current evidence, while weak, indicates that QKL carries a low risk of ADR/AE, and some adverse events that do occur may be ascribed to improper use of the drug. Reporting of ADR/AEs needs to be greatly improved, and should follow the ‘Recommendations for reporting traditional Chinese medicine adverse drug reaction”.
Temporary storage of fresh frozen plasma above −30°C has no negative impact on the quality of clotting factors and inhibitors
Authors: MOOG RAINER , KNOP DIETMAR , WENZEL FOLKER
Published: April 2010

Fresh frozen plasma (FFP) should be stored at temperatures > −30°C according to national and international guidelines to maintain the stability of clotting factors and inhibitors. In the present report, FFP was accidentally stored at < −30°C due to icing of the freezer. To ensure the quality of the FFPs a battery of tests of clotting factors and inhibitors was performed. Our data demonstrate that temporary storage of FFP at temperature < −30°C does not negatively affect the quality of FFPs. The European requirement of 70% activity of factor VIII was met by all units.
On the Feasibility of Catastrophic Cutting Tool Fracture Prediction Via Acoustic Emission Analysis
Authors: Rice J. A. , Wu S. M.
Published: April 2010

The prediction of catastrophic cutting tool fracture is explored through monitoring the acoustic emission (AE) from a cutting process. A prediction parameter is derived which combines the AE signal with a physical model of a cracked tool to form an estimate of the spatial energy release rate. Monitoring the energy release rate is found to be largely dependent on the detection of crack advancement. Experiments were performed with both new and artificially cracked inserts during interrupted cutting. Epoches denoting crack advancement were detected through high time homomorphic analysis of the acquired AE signals. AE bursts prior to and leading up to fracture were analyzed for crack advancement. The calculated energy release rate was found to exponentially increase as fracture was approached. Crack advancement could be feasibly detected approximately six cuts prior to fracture.
Effects of Feedrate and Chisel Edge on Delamination in Composites Drilling
Authors: Jain S. , Yang D. C. H.
Published: April 2010

Delamination accompanied with the drilling of composite laminates has been recognized as a major problem. An analytical model is established to predict critical thrust force and critical feedrate at which the delamination crack begins to propagate. For unidirectional composites, the delamination zone is modeled as an elliptical plate, with clamped edges and subjected to a central load. Based on fracture mechanics, laminated plate theory and cutting mechanics, expressions are developed for critical thrusts and critical feedrates at which delamination is initiated at different ply locations. This model has been verified by experiments. A variable feedrate strategy is formulated based on this model, which avoids delamination while drilling in a time-optimal fashion. In addition, the need to modify tool geometry to avoid delamination is highlighted. Chisel edge width has been identified as an important factor contributing to the thrust force and hence delamination.
Optimal Rough Machining of Sculptured Parts on a CNC Milling Machine
Authors: Dong Z. , Li H. , Vickers G. W.
Published: April 2010

An optimal approach to the rough machining of sculptured parts with least machining time is presented. The contour map cutting method is used to generate CNC tool paths based on the CAD model of sculptured parts. The part and stock geometry related parameters, including the number of cutting layers and the distributions of cutting depth, and the process parameters of feed rate and depth of cut, are optimized. The method can automate CNC programming for sculptured part rough machining, considerably improve productivity, and lower production costs. Two examples are used to illustrate the approach and its advantages.
A Study of the Vibrational Dynamics of an Endrill Clamped by Side-Locking
Authors: Rahman M. , Matin M. A. , Seah K. H. W.
Published: April 2010

An endrill is clamped by a side-locking device. The shape of a hole obtained by such a drill is found to be of a distorted oval shape. Fourier analysis of the process reveals that the out-of-roundness of the hole is due to the harmonic variation of the centrifugal force developed on the drill-bit. The chattering ranges of the spindle speed are also shown in a stability chart representing the frequency response of the system.
Establishing a Methodology for Resolving Convective Heat Transfer From Complex Geometries
Authors: Ostanek Jason K. , Prausa J. , Van Suetendael A. , Thole Karen A.
Published: April 2010

Current turbine airfoils must operate at extreme temperatures, which are continuously driven higher by the demand for high output engines. Internal cooling plays a key role in the longevity of gas turbine airfoils. Ribbed channels are commonly used to increase heat transfer by generating turbulence and to provide a greater convective surface area. Because of the increasing complexity in airfoil design and manufacturing, a methodology is needed to accurately measure the convection coefficient of a rib with a complex shape. Previous studies that have measured the contribution to convective heat transfer from the rib itself have used simple rib geometries. This paper presents a new methodology to measure convective heat transfer coefficients on complex ribbed surfaces. The new method was applied to a relatively simple shape so that comparisons could be made with a commonly accepted method for heat transfer measurements. A numerical analysis was performed to reduce experimental uncertainty and to verify the lumped model approximation used in the new methodology. Experimental measurements were taken in a closed-loop channel using fully rounded discontinuous skewed ribs oriented 45 deg to the flow. The channel aspect ratio was 1.7:1 and the ratio of rib height to hydraulic diameter was 0.075. Heat transfer augmentation levels relative to a smooth channel were measured to be between 4.7 and 3 for Reynolds numbers ranging from 10,000 to 100,000.
Efficient Finite Element Analysis/Computational Fluid Dynamics Thermal Coupling for Engineering Applications
Authors: Sun Zixiang , Chew John W. , Hills Nicholas J. , Volkov Konstantin N. , Barnes Christopher J.
Published: April 2010

An efficient finite element analysis/computational fluid dynamics (FEA/CFD) thermal coupling technique has been developed and demonstrated. The thermal coupling is achieved by an iterative procedure between FEA and CFD calculations. Communication between FEA and CFD calculations ensures continuity of temperature and heat flux. In the procedure, the FEA simulation is treated as unsteady for a given transient cycle. To speed up the thermal coupling, steady CFD calculations are employed, considering that fluid flow time scales are much shorter than those for the solid heat conduction and therefore the influence of unsteadiness in fluid regions is negligible. To facilitate the thermal coupling, the procedure is designed to allow a set of CFD models to be defined at key time points/intervals in the transient cycle and to be invoked during the coupling process at specified time points. To further enhance computational efficiency, a “frozen flow” or “energy equation only” coupling option was also developed, where only the energy equation is solved, while the flow is frozen in CFD simulation during the thermal coupling process for specified time intervals. This option has proven very useful in practice, as the flow is found to be unaffected by the thermal boundary conditions over certain time intervals. The FEA solver employed is an in-house code, and the coupling has been implemented for two different CFD solvers: a commercial code and an in-house code. Test cases include an industrial low pressure (LP) turbine and a high pressure (HP) compressor, with CFD modeling of the LP turbine disk cavity and the HP compressor drive cone cavity flows, respectively. Good agreement of wall temperatures with the industrial rig test data was observed. It is shown that the coupled solutions can be obtained in sufficiently short turn-around times (typically within a week) for use in design.
Suction-Side Gill
Region Film Cooling: Effects of Hole Shape and Orientation on Adiabatic Effectiveness and Heat
Transfer Coefficient
Authors: Chappell Justin , Ligrani Phil , Sreekanth Sri , Lucas Terry
Published: April 2010

The performance of suction-side gill region film cooling is investigated using the University of Utah transonic wind tunnel and a simulated turbine vane in a two-dimensional cascade. The effects of film cooling hole orientation, shape, and number of rows, and their resulting effects on thermal film cooling characteristics, are considered for four different hole configurations: round axial (RA), shaped axial (SA), round radial (RR), and round compound (RC). The mainstream Reynolds number based on axial chord is 500,000, the exit Mach number is 0.35, and the tests are conducted using the first row of holes only, second row of holes only, or both rows of holes at blowing ratios of 0.6 and 1.2. Carbon dioxide is used as the injectant to achieve density ratios of 1.73 to 1.92 similar to values present in operating gas turbine engines. A mesh grid is used to give a magnitude of longitudinal turbulence intensity of 5.7% at the inlet of the test section. Results show that the best overall protection over the widest range of blowing ratios and streamwise locations is provided by either the RC holes or the RR holes. This result is particularly significant because the RR hole arrangement, which has lower manufacturing costs compared with the RC and SA arrangements, produces better or equivalent levels of performance in terms of magnitudes of adiabatic film cooling effectiveness and heat transfer coefficient. Such improved performance (relative to RA and SA holes) is most likely a result of compound angles, which increases lateral spreading. As such, the present results indicate that compound angles appear to be more effective than hole shaping in improving thermal protection relative to that given by RA holes.
Interaction of Wheelspace Coolant and Main Flow in a New Aeroderivative Low Pressure Turbine
Authors: Montomoli F. , Massini M. , Maceli N. , Cirri M. , Lombardi L. , Ciani A. , D’Ercole M. , De Prosperis R.
Published: April 2010

Increased computational capabilities make available for the aero/thermal designers new powerful tools to include more geometrical details, improving the accuracy of the simulations and reducing design costs and time. In the present work, a low-pressure turbine was analyzed, modeling the rotor-stator including the wheel space region. Attention was focused on the interaction between the coolant and the main flow in order to obtain a more detailed understanding of the behavior of the angel wings, to evaluate the wall heat flux distribution, and to prevent hot gas ingestion. Issues of component reliability related to thermal stress require accurate modeling of the turbulence and unsteadiness of the flow field. To satisfy this accuracy requirement, a full 3D URANS simulation was carried out. A reduced count ratio technique was applied in order to decrease numerical simulation costs. The study was carried out to investigate a new two-stage low-pressure turbine from GE Infrastructure Oil & Gas to be coupled to a new aeroderivative gas generator (the LM2500+G4) developed by GE Infrastructure, Aviation.
On the Numerical Determination of Shrinkage Stresses
Authors: Bauer F. , Reiss E. L.
Published: April 2010

An iterative method is employed to obtain numerical solutions of a two-dimensional mixed boundary-value problem for rectangular elastic plates. The theory of plane stress is used. This problem is encountered when the edge of a uniformly heated plate is bonded to a rigid body and then allowed to cool. The numerical results are compared with two formal asymptotic expansions of the solution. They correspond to the limiting cases of a thin strip and a long strip. The development of boundary layers near the edges of the plate is observed. The numerically determined stresses achieve their largest values at the corner of the bonded edge.
Transient Motion of an Elastic Half Space Due to a Semi-Infinite Surface Line Load
Authors: Gakenheimer D. C.
Published: April 2010

A method is described for obtaining an exact transient solution to the problem of an elastic half space whose surface is excited by a semi-infinite line load. The load acts normal to the surface of the half space and it has impulsive time-dependence. The resulting displacement field is discussed.
An Expansion Bellows Problem
Authors: Clark R. A.
Published: April 2010

An elastic bellows consisting of a shell of revolution with deep, periodic, circumferential corrugations is analyzed by a method of asymptotic integration. Approximate formulas are obtained for the stresses and axial deflection due to an axial load.
Applications of Holography to Dynamics: High-Frequency Vibrations of Beams
Authors: Aprahamian R. , Evensen D. A.
Published: April 2010

The relatively new experimental technique of holographic interferometry is described, and time-average holography is discussed. Time-average holography has been applied to study high-frequency transverse vibrations of a uniform cantilever beam. Modes from the 5th through the 34th were identified and recorded on holograms, the corresponding resonant frequencies ranged from 500–25,665 cps. In addition, the 77th mode was recorded at 99,395 cps, which demonstrates that the technique is workable at frequencies on the order of 100 kc. The experimental mode shapes and frequencies show good correlation with the Timoshenko beam theory. Other applications of holography to dynamics are briefly discussed.
Elastoplastic Wave Propagation in a Rate-Sensitive Finite Rod Having a Thermal Gradient
Authors: Francis P. H.
Published: April 2010

In this paper, the problem of one-dimensional wave propagation in a bar of a thermally sensitive viscoplastic material is considered. A constitutive equation is developed which explicitly accounts for the thermal state in both the elastic and inelastic components of the strain rate. A computational technique is proposed for solving the governing hyperbolic system of equations. This technique is a synthesis of the finite-difference method and the method of characteristics, and utilizes the most attractive features of both for solving nonlinear problems involving the propagation of strong discontinuities. Some results are shown for the propagation of waves through both decreasing and increasing temperature fields.
Stress-Wave Generation in a Temperature-Dependent Absorbing Solid by Impulsive Electromagnetic Radiation
Authors: Hegemier G. A. , Tzung F.
Published: April 2010

An elastic, partially transparent solid, occupying the half space x > 0, is subjected to uniform impulsive electromagnetic radiation at the surface x = 0. The deposition of radiant energy over a finite absorption depth gives rise to a distributed heat source within the solid (thermal shock) which, in turn, dilatates the medium and generates a stress wave. In this paper, the nature of the stress-wave buildup in the absorption layer is studied for the case of a temperature-dependent solid, i.e., when material properties vary with temperature. The mathematical problem is one of wave propagation in a nonhomogeneous medium. An approximate solution to the posed problem is developed which readily exhibits the influence of temperature. Error bounds are provided. The results are illustrated by a numerical example.
Scattering of Stress Waves by a Circular Elastic Cylinder Embedded in an Elastic Medium
Authors: Ko W. L.
Published: April 2010

Scattering of stress waves by a circular elastic cylinder embedded in an elastic medium is investigated. The axis of the scatterer is perpendicular to the propagation vector of the incident plane compressional stress pulse wave. Making use of modified Kirchhoff’s integral formulas developed for elastodynamics by Ko [1], wave-front stresses and displacements during the early stage of interaction are obtained for both interior and exterior fields, and for the scatterer-medium interface. The solutions are valid for the whole spectrum of material properties of the scatterer ranging from void to infinitely dense materials. It is found that Kirchhoff’s method of retarded potentials predicts singular wave-front response at caustics as does the geometrical acoustics. The basic integral equations presented are applicable to a scatterer of arbitrary shape and do not only give the wave-front solution, but also the solutions after the arrival of the wave front.
A General Formulation of the Optimal Frame Problem
Authors: Grierson D. E. , Cohn M. Z.
Published: April 2010

Optimal design techniques have been extensively applied to steel structures and, to a lesser degree, to reinforced concrete structures. In the latter case, for given geometry and preassigned stiffnesses, optimal designs have been found which simultaneously satisfy (a) limit equilibrium (plastic limit stage), (b) serviceability (elastic limit stage), and (c) optimality (minimum material consumption). The limitations to these designs are: 1. A subsequent check of plastic compatibility may invalidate the design. 2. The resulting member stiffnesses may differ appreciably from the preassigned values. 3. A different geometry may result in a better solution while still satisfying all design criteria. The present paper attempts to eliminate these limitations through a more general formulation of the optimal frame problem wherein design plastic moments, member stiffnesses, and frame geometry are all treated as variables and are found for simultaneous satisfaction of (a) optimality, (b) limit equilibrium, (c) serviceability, (d) plastic compatibility, and (e) elastic compatibility. With some simplifying assumptions to linearize the problem, the general formulation is illustrated for a reinforced concrete continuous beam example. The resulting optimal design is compared with conventional elastic and plastic designs with respect to safety, serviceability, compatibility, and efficiency.
On Extending the Range of Applicability of the Limit Theorems
Authors: McLaughlin P. V. , Batterman S. C.
Published: April 2010

It is commonly thought that the limit theorems of ideal plasticity are restricted to perfectly plastic material or structural behavior and to the requirement of no essential change in geometry. The present paper shows that the limit theorems are applicable to a broader class of phenomena and that the no essential geometry change requirement can be unduly restrictive. In particular, constant load elastic buckling and pullout of fibers from composite materials are both admissible limit phenomena and can be handled within the framework of limit analysis.
Eigenstructure of First-Order Velocity-Stress Equations for Waves in Elastic Solids of Trigonal 32 Symmetry
Authors: Yang Lixiang , Chen Yung-Yu , Yu S.-T. John
Published: April 2010

This paper reports the eigenstructure of a set of first-order hyperbolic partial differential equations for modeling waves in solids with a trigonal 32 symmetry. The governing equations include the equation of motion and partial differentiation of the elastic constitutive relation with respect to time. The result is a set of nine, first-order, fully coupled, hyperbolic partial differential equations with velocity and stress components as the unknowns. Shown in the vector form, the model equations have three 9×9 coefficient matrices. The wave physics are fully described by the eigenvalues and eigenvectors of these matrices; i.e., the nontrivial eigenvalues are the wave speeds, and a part of the corresponding left eigenvectors represents wave polarization. For a wave moving in a certain direction, three wave speeds can be identified by calculating the eigenvalues of the coefficient matrix in a rotated coordinate system. In this process, without using the plane-wave solution, we recover the Christoffel matrix and thus validate the formulation. To demonstrate this approach, two- and three-dimensional slowness profiles of quartz are calculated. Wave polarization vectors for wave propagation in several compression directions as well as noncompression directions are discussed.
Engineering of threshold voltages in molecular beam epitaxy-grown Al2O3∕Ga2O3(Gd2O3)∕In0.2Ga0.8As
Authors: Wu Y. D. , Lin T. D. , Chiang T. H. , Chang Y. C. , Chiu H. C. , Lee Y. J. , Hong M. , Lin C. A. , Kwo J.
Published: April 2010

The metal-oxide-semiconductor (MOS) capacitors of Al2O3∕Ga2O3(Gd2O3) on n- and p-type In0.2Ga0.8As with different metal gates exhibited excellent capacitance-voltage (C-V) characteristics and remarkable thermodynamic stability after rapid thermal annealing up to 850°C. The flat-band voltage (Vfb), flat-band voltage shift (ΔVfb), threshold voltage (Vth), and frequency dispersion of the MOS capacitors with different metal gates were extracted from the C-V curves. The Vth values of Al2O3∕Ga2O3(Gd2O3)∕p-In0.2Ga0.8As were calculated to be about 0.04V (Al gate) and 1.15V (Ni gate) and those of Al2O3∕Ga2O3(Gd2O3)∕n-In0.2Ga0.8As −1.94V (Al gate) and −0.88V (Ni gate). The correlation between flat-band voltage and different metal gates indicates unpinned Fermi levels at the metal/dielectric interfaces.
Suppression of surface leakage currents using molecular beam epitaxy-grown unipolar barriers
Authors: Savich G. R. , Pedrazzani J. R. , Maimon S. , Wicks G. W.
Published: April 2010

The performance of many electronic devices and materials is limited by surface leakage. These currents are conventionally inhibited by post-epitaxy deposition of a surface passivation layer. This work presents the use of epitaxial, unipolar barriers to limit surface leakage currents, which are a more effective and less expensive approach to control surface current than surface passivation. The concept is illustrated with molecular beam epitaxy-grown InAs photodiodes. The dark current in a conventional InAs photodiode is dominated by surface conduction at temperatures below 150 K, whereas the unipolar barrier InAs photodiode exhibits no detectable surface leakage.
Optical study of strongly coupled CdSe quantum dots
Authors: Zhang S. K. , Myint Thander , Wang W. B. , Das B. B. , Perez-Paz Noemi , Lu H. , Tamargo M. C. , Shen A. , Alfano R. R.
Published: April 2010

Electronic coupling of vertically stacked CdSe quantum dots is investigated by photoluminescence (PL), time-resolved photoluminescence (t-PL) techniques and Raman techniques. Five samples with each containing 30 layers of self-assembled CdSe quantum dots were grown over InP substrate by molecular beam epitaxy method. The nominal deposition thickness of CdSe layers is 3 ML (monolayer) for all samples. The barrier layers, ZnCdMgSe with MgSe fraction of 59%, were grown with different deposition times to produce different thicknesses of 14, 15, 20, 22, and 25 Å. Strong scattering from lomgitudinal-optical phonons of CdSe quantum dots was observed at 228 cm-1 in Ramen spectroscopy. Photoluminescence spectra and time-resolved photoluminescence spectra were measured at 77 K. With decreasing of barrier thickness, the PL peak shifts to low energy side. This indicates that thinner spacing barrier results in stronger interdot coupling. The lifetime of electrons for each sample was determined by fitting the t-PL data. With the reduction in barrier thickness, the lifetime of electrons increases accordingly. The strong coupling of dots hinders carriers from escaping from quantum dots, thus prolonging carrier lifetime.
Tip-sample interactions on graphite studied in the thermal oscillation regime
Authors: Malegori Giovanna , Ferrini Gabriele
Published: April 2010

Thermal noise is caused by random thermal excitations that result in positional fluctuations of the cantilever, thereby setting a lower limit on the force resolution of an atomic force microscope (AFM). However, thermal noise can also be utilized for measurement purposes. Here, the authors present three different approaches to exploit the information contained in the cantilever thermal motion (frequency shift, Brownian motion, and thermal mean square displacement) and some results concerning the characterization of the AFM system in the thermal driving regime.
Structural analysis of thin epitaxial Y2O3 films on sapphire
Authors: Webster S. E. , Kumaran R. , Penson S. , Tiedje T.
Published: April 2010

High structural quality yttrium oxide films have been grown on R-plane sapphire by molecular beam epitaxy. X-ray diffraction measurements showed clear pendellösung fringes and sharp peaks. X-ray measurements indicate that the films grow nearly perfectly up to a critical thickness with x-ray peak widths as low as 7 arc sec. This critical thickness increases with decreasing growth rate up to 7 nm at 10 nm/h. The optimal growth temperature was found to be 800 °C. Evidence of short range (<10 nm) surface diffusion is presented.
Study of rapid thermal annealing effect on CdZnO thin films grown on Si substrate
Authors: Li L. , Yang Z. , Zuo Z. , Kong J. Y. , Liu J. L.
Published: April 2010

CdZnO thin films were grown on Si (100) substrates by plasma-assisted molecular beam epitaxy. As-grown samples show near band edge emissions at 1.87, 2.03, and 2.16 eV, respectively, while the emission peak energy dramatically increases to up to ultraviolet region with increasing rapid thermal annealing temperature. Room temperature photoluminescence (PL), and temperature dependent PL show phase separations in the samples after the annealing process. Secondary ion mass spectroscopy measurements show redistribution of Cd in the as-annealed sample, which is believed to be the reason of PL peaks shift.
Ultraviolet light emissions in MgZnO/ZnO double heterojunction diodes by molecular beam epitaxy
Authors: Kong Jieying , Li Lin , Yang Zheng , Liu Jianlin
Published: April 2010

ZnO double heterojunction structure was grown by molecular beam epitaxy. 100 nm MgZnO/ZnO/MgZnO well was inserted between Ga-doped ZnO and Sb-doped ZnO layers. X-ray diffraction spectrum confirmed the preferential growth along c-direction and secondary ion mass spectroscopy measurements showed a clear double heterojunction profile of this structure. Thin MgZnO layers made no difficulties for electrons and holes to get into active intrinsic ZnO layer. Dominant ultraviolet electroluminescence was observed at the injection currents from 40 to 80 mA at room temperature. The output power was 7.3 times as that from p-n homojunction diode at the same driving current due to a good confinement of electrons and holes in the intrinsic ZnO layer.
SU‐DD‐A1‐03: Beam's‐Eye‐View Dosimetrics Guided Inverse Planning for Aperture Modulated Arc Therapy
Authors: Ma Y , Xing L
Published: April 2010

Purpose: To utilize angular beam's‐eye‐view dosimetrics (BEVD) information to improve the computational efficiency and plan quality of inverse planning of aperture modulated arc therapy (AMAT). Materials & Methods: In BEVD‐guided inverse planning, the angular space spanned by a rotational arc is represented by a large number of fixed‐gantry beams with angular spacing of ∼2.5°. Each beam is assigned with an initial aperture shape determined by the beam's‐eye‐view (BEV) projection of the planning target volume (PTV) and an initial weight. Instead of setting the beam weights arbitrarily, which slows down the subsequent optimization process and may result in a sub‐optimal solution, a‐priori knowledge about the quality of the beam directions derived from a BEVD is adopted to initialize the weights. In the BEVD calculation, a higher score is assigned to directions that allow more dose to be delivered to the PTV without exceeding the dose tolerances of the organs at risk (OARs), and vice versa. Simulated annealing is then utilized to optimize the segment shapes and weights. The BEVD‐guided inverse planning is demonstrated by using a pancreatic case and the results are compared with conventional approach without BEVD guidance. Results: An a‐priori knowledge guided inverse planning scheme for AMAT is established. The inclusion of BEVD guidance significantly improves the convergence behavior of AMAT inverse planning and results in much better OAR sparing as compared to the conventional approach. Conclusions: BEVD‐guidance facilitates AMAT treatment planning and provides a comprehensive tool to maximally utilize the technical capacity of the new arc therapeutic modality.
SU‐DD‐A1‐06: RapidArc Patient Specific Quality Assurance: Comparison with DMLC IMRT
Authors: Popple R , Brezovich I , Duan J , Shen S , Wu X
Published: April 2010

Purpose: To compare RapidArc (Varian Medical Systems) intensity modulated arc therapy and dynamic multileaf collimated IMRT (DMLC) delivery accuracy using patient specific quality assurance measurements. Method and Materials: We selected 6 cases (head and neck, para‐aortic lymph nodes, and 4 prostates) that were treated using both DMLC and RapidArc. The DMLC and RapidArc plans were equivalent with respect to target and critical structure dosimetry. Absolute dose measurements were made with an ionization chamber in a custom acrylic phantom, which was positioned such that the chamber was located in a high‐dose, low‐gradient region of the dose distribution. Film was used to obtain the dose distribution in a coronal plane at the level of the ionization chamber. A 2D ionization chamber array (Matrixx, IBA Dosimetry) was used to obtain a second measurement in the same coronal plane. The gamma index was calculated for both the film and 2D array measurements using the criteria of 3%/3mm. Results: The mean difference between the ionization chamber measurements and the calculations was 1.0% for both RapidArc and DMLC. The ranges were 0.6% to 1.6% and 0.0% to 2.3%, respectively. The mean fraction of pixels with gamma > 1 for the film was 4.3% (range 0.8% to 6.9%) for RapidArc and 10.4% (range 5.4% to 17.3%) for DMLC. For the 2D array the mean fraction of pixels with gamma > 1 was 0.5% (range 0.0% to 1.1%) for RapidArc and 1.6% (range 0.5% to 4.1%) for DMLC. Conclusion: The results demonstrate that RapidArc delivery is at least as accurate as that for DMLC. The mean fraction of pixels with gamma >1 and the range of fractions for both film and the 2D chamber array suggests that RapidArc may be modestly more accurate than DMLC.

Conflict of Interest: Research sponsored by Varian Medical Systems.