bluuebunny/crossref_metadata_2025 huggingface dataset:
Methamphetamine exposure during brain development alters the brain acetylcholine system in adolescent mice
Authors: Siegel Jessica A. , Park Byung S. , Raber Jacob
Published: August 2011

J. Neurochem. (2011) 119, 89–99.

Children exposed to methamphetamine during brain development as a result of maternal drug use have long‐term hippocampus‐dependent cognitive impairments, but the mechanisms underlying these impairments are not understood. The acetylcholine system plays an important role in cognitive function and potential methamphetamine‐induced acetylcholine alterations may be related to methamphetamine‐induced cognitive impairments. In this study, we investigated the potential long‐term effects of methamphetamine exposure during hippocampal development on the acetylcholine system in adolescence mice on postnatal day 30 and in adult mice on postnatal day 90. Methamphetamine exposure increased the density of acetylcholine neurons in regions of the basal forebrain and the area occupied by acetylcholine axons in the hippocampus in adolescent female mice. In contrast, methamphetamine exposure did not affect the density of GABA cells or total neurons in the basal forebrain. Methamphetamine exposure also increased the number of muscarinic acetylcholine receptors in the hippocampus of adolescent male and female mice. Our results demonstrate for the first time that methamphetamine exposure during hippocampal development affects the acetylcholine system in adolescent mice and that these changes are more profound in females than males.
Anticoagulant management in the cardiovascular setting
Authors: Verheugt Freek W.A.
Published: August 2011

Vitamin K antagonists have been used as oral anticoagulants (OACs) for over five decades, yet their use in real‐world practice is problematic primarily because of their narrow therapeutic window, exacerbated by extensive food and drug interactions, necessitating regular coagulation monitoring and dose adjustment. Around half of patients receiving warfarin are within the therapeutic range, exposing them to the dangers of under‐anticoagulation (i.e. thrombosis formation) or over‐anticoagulation (i.e. bleeding). A new generation of OACs with improved pharmacology promises to revolutionize antithrombotic management. Rivaroxaban, apixaban (both oral direct Factor Xa inhibitors) and dabigatran (a direct thrombin inhibitor) all exhibit predictable anticoagulant responses and few drug–drug interactions and do not require routine coagulation monitoring.
Differences in foraging ecology determine variation in visual fields in ibises and spoonbills (Threskiornithidae)
Authors: MARTIN GRAHAM R. , PORTUGAL STEVEN J.
Published: August 2011

Variations in visual field topography among birds have been interpreted as adaptations to the specific perceptual challenges posed by the species’ foraging ecology. To test this hypothesis we determined visual field topography in four bird species which have different foraging ecologies but are from the same family: Puna Ibis Plegadis ridgwayi (probes for prey in the soft substrates of marsh habitats), Northern Bald Ibis Geronticus eremita (surface pecks for prey in dry terrestrial habitats), African Spoonbill Platalea alba and Eurasian Spoonbill Platalea leucorodia (bill‐sweeps for prey in shallow turbid waters). All four species employ tactile cues provided by bill‐tip organs for prey detection. We predicted that the visual fields of these species would show general features similar to those found in other birds whose foraging is guided by tactile cues from the bill (i.e. bill falling outside the frontal binocular field and comprehensive visual coverage of the celestial hemisphere). However, the visual fields of all four species showed general features characteristic of birds that take food directly in the bill under visual guidance (i.e. a narrow and vertically long binocular field in which the projection of the bill tip is approximately central and with a blind area above and behind the head). Visual fields of the two spoonbills were very similar but differed from those of the ibises, which also differed between themselves. In the spoonbills, there was a blind area below the bill produced by the enlarged spatulate bill tip. We discuss how these differences in visual fields are related to the perceptual challenges of these birds’ different foraging ecologies, including the detection, identification and ingestion of prey. In particular we suggest that all species need to see binocularly around the bill and between the opened mandibles for the identification of caught prey items and its transport to the back of the mouth. Our findings support the hypothesis that sensory challenges associated with differences in foraging ecology, rather than shared ancestry or the control of locomotion, are the main determinants of variation in visual field topography in birds.
Is there an underestimation of intima‐media thickness based on M‐mode ultrasound technique in the abdominal aorta?
Authors: Dahlén Elsa M. , Andreasson Thomas , Cinthio Magnus , Nystrom Fredrik H. , Östgren Carl Johan , Länne Toste
Published: August 2011

Measuring intima‐media thickness (IMT) in the common carotid artery (CCA) is a valuable resource for the evaluation of subclinical atherosclerosis. The main objective of this study was to explore whether a B‐mode ultrasound technique, Philips ATL, and an M‐mode ultrasound technique, Wall Track System (WTS), show interchangeable results when measured in CCA and the abdominal aorta (AA). A total of 24 healthy, young subjects were examined. IMT and lumen diameter (LD) of the AA and the CCA were measured twice by two skilled ultrasonographers with two different ultrasound equipment B‐mode: (Philips, ATL and M‐mode: WTS).The intra‐observer variability of IMT in CCA and AA using B‐mode showed a coefficient of variation 8% and 9%, and with M‐mode 11% and 15%, respectively. Interobserver variability of IMT in CCA and AA using B‐mode was 6% and 12%, and with M‐mode 11% and 18%, respectively. CCA IMT was 0·53 ± 0·07 and 0·53 ± 0·09 mm using B‐mode and M‐mode, respectively. However, in AA, IMT was 0·61 ± 0·05 and 0·54 ± 0·10 mm using B‐mode and M‐mode, respectively. Thus, AA IMT was 11·5% thicker using B‐mode (P<0·01). We received adequate IMT readings from the carotid artery as well as the AA using two commonly used B‐mode and M‐mode techniques. B‐mode technique seems to show less variability, especially in the AA. More importantly, the two techniques measured different IMT thickness in the aorta, emphasizing the importance of using similar technique when comparing the impact of absolute values of IMT on cardiovascular disease.
The Accuracy of Present‐on‐Admission Reporting in Administrative Data
Authors: Goldman L. Elizabeth , Chu Philip W. , Osmond Dennis , Bindman Andrew
Published: August 2011

Objective

To test the accuracy of reporting present‐on‐admission (POA) and to assess whetherPOAreporting accuracy differs by hospital characteristics.

Data Sources

We performed an audit ofPOAreporting of secondary diagnoses in 1,059 medical records from 48California hospitals.

Study Design

We used patient discharge data (PDD) to select records with secondary diagnoses that are powerful predictors of mortality and could potentially represent comorbidities or complications among patients who either had a primary procedure of a percutaneous transluminal coronary angioplasty or a primary diagnosis of acute myocardial infarction, community‐acquired pneumonia, or congestive heart failure. We modeled the relationship between secondary diagnosesPOAreporting accuracy (over‐reporting and under‐reporting) and hospital characteristics.

Data Collection

We created a gold standard from blind reabstraction of the medical records and compared the accuracy of thePDDagainst the gold standard.

Principal Findings

ThePDDand gold standard agreed onPOAreporting in 74.3 percent of records, with 13.7 percent over‐reporting and 11.9 percent under‐reporting. For‐profit hospitals tended to overcode secondary diagnoses as present on admission (odds ratios [OR] 1.96; 95 percent confidence interval [CI] 1.11, 3.44), whereas teaching hospitals tended to undercode secondary diagnoses as present on admission (OR2.61; 95 percentCI1.36, 5.03).

Conclusions

POA reporting of secondary diagnoses is moderately accurate but varies by hospitals. Steps should be taken to improvePOAreporting accuracy before usingPOAin hospital assessments tied to payments.
Interaction of innovative small molecule drugs used for cancer therapy with drug transporters
Authors: Mandery K , Glaeser H , Fromm MF
Published: August 2011

Multiple new small molecules such as tyrosine kinase, mammalian target of rapamycin (mTOR) and proteasome inhibitors have been approved in the last decade and are a considerable progress for cancer therapy. Drug transporters are important determinants of drug concentrations in the systemic circulation. Moreover, expression of drug transporters in blood–tissue barriers (e.g. blood–brain barrier) can limit access of small molecules to the tumour (e.g. brain tumour). Finally, transporter expression and (up)regulation in the tumour itself is known to affect local drug concentrations in the tumour tissue contributing to multidrug resistance observed for multiple anticancer agents. This review summarizes the current knowledge on: (i) small molecules as substrates of uptake and efflux transporters; (ii) the impact of transporter deficiency in knockout mouse models on plasma and tissue concentrations; (iii) small molecules as inhibitors of uptake and efflux transporters with possible consequences for drug–drug interactions and the reversal of multidrug resistance; and (iv) on clinical studies investigating the association of polymorphisms in genes encoding drug transporters with pharmacokinetics, outcome and toxicity during treatment with the small molecules.
Temperature Dependence on Domain Switching Behavior in Lead Zirconate Titanate Under Electrical Load via In Situ Neutron Diffraction
Authors: Pojprapai Soodkhet , Simons Hugh , Studer Andrew J. , Luo Zhenhua , Hoffman Mark
Published: August 2011

The influence of temperature on the kinetics of domain switching in lead zirconate titanate was investigated by using in situ neutron diffraction. Samples were electrically loaded to 1 kV/mm at 30°C, 125°C, and 175°C, after which the diffracted patterns in the on‐ and off‐state were compared. The results demonstrated that the degree of domain switching increases with increased temperature. Corroboration with hysteresis measurements showed that while the coercive field decreases with increasing temperature, the degree of saturation increased significantly. According to Merz's model, it is therefore apparent that, due to increased switching rate at high temperature, domain switchability increases with temperature.
A Monte‐Carlo Approach for Modeling Glass Transition
Authors: Ruan H. H. , Zhang L. C.
Published: August 2011

Glass transition is an important factor in the thermo‐forming of glass elements of precision geometries, such as optical glass lenses. Based on the theory of potential energy landscape, the master equations can be established to describe the slowdown of atomic motions in the glass transition range. However, the direct solution of these master equations is almost formidable as the hopping rates between basins vary in many orders of magnitude. To make use of the master equations in the finite element simulation of thermo‐forming process, this article develops a Metropolis stochastic process by assuming that the basin‐hopping probability at a given time interval depends only on the relative hopping rate between the target state and the present state. It was shown that with an infinitesimal time interval, this stochastic description degenerates to the master equations, and that with coarse time steps, the efficiency can be greatly improved with good accuracy. The advantage of this new method was demonstrated through the glass transition and thermo‐forming simulations of selenium by integrating the stochastic process with the finite element method via the constitutive description of the variation of volume and viscosity with temperature and time.
Retrospective Evaluation of Attention Deficit Hyperactivity Disorder with the Wender Utah Rating Scale in a Sample of Spanish Prison Inmates
Authors: Vegue‐González Milagros , Álvaro‐Brun Enrique , Santiago‐Sáez Andrés , Kanaan‐Kanaan Atef
Published: August 2011

Abstract:  The aim of this study is to determine the prevalence of childhood history of attention deficit hyperactivity disorder (ADHD) in a sample of prison inmates. This is a descriptive, cross‐sectional study, which consisted of a sample of 100 inmates from penitentiary centers in Madrid. The instruments used were the Wender Utah Rating Scale (WURS), the International Personality Disorder Examination, and a questionnaire of demographic, penitentiary, and toxicological data. For statistical analysis, the SPSS program was used with confidence interval estimation of 95%. The mean score of the WURS was 65.7 points. Fifty percent of the sample surpassed the cut‐off point of 32 for the 25 best discriminative items in the Spanish validated version. A significant association was found between a childhood history of ADHD and antisocial and borderline personality disorders. The disorder was also found to be associated with autoaggressive behavior, more probability to be sanctioned in prison, and have a history of substance dependence.
Selective feedback between dispersal distance and the stability of mutualism
Authors: Mack Keenan M. L.
Published: August 2011

The evolution and maintenance of mutually beneficial interactions has been one of the oldest problems for evolutionary theory. For cooperation to be stable, mechanisms such as spatial population structure must exist that prevent non‐cooperative individuals from invading cooperative groups. Selection for certain traits like increased dispersal can erode that structure. Here, I used a spatially explicit individual based dual lattice computer simulation to investigate how the evolution of dispersal interacts with the evolution of mutualism and how this interaction affects the stability of mutualism in the face of non‐mutualists. I ran simulations manipulating the self‐structuring phenotype, dispersal distance, over a range of environmental conditions, as well as letting both dispersal and mutualism evolve independently, with and without a cost of dispersal. I found that environmental productivity is negatively correlated with the stability of mutualism, and that the stability of mutualism relied on the ability of mutualists to evolve shorter dispersal distances than non‐mutualists. The inclusion of a dispersal cost essentially fixed the upper limit of dispersal, and therefore limits the ability of non‐mutualists to evolve higher average dispersal than mutualists, but as costs are relaxed, the differences are recovered. These results show how selection on seemingly unrelated traits can align suites of traits into holistic life history strategies.
Bergmann's rule encompasses mechanism: a reply to Olalla‐Tárraga (2011)
Authors: Watt Cortney , Salewski Volker
Published: August 2011

The many definitions of Bergmann's rule have resulted in confusion and debate over how and in what organisms to test the original rule. Watt et al. published a paper in 2010, based directly on Bergmann's original paper, in the hopes of clarifying the rule and presenting direct translations to resolve uncertainties. Recently, Olalla‐Tárraga has criticized our publication, stating that we assumed the rule was a causal law, which has narrowed our epistemological scope of the rule. We argue we did not assume the rule was a law and suggest that Olalla‐Tárraga has only focused on the observed pattern and has ignored the proposed mechanism, which is inherent in the definition. We also discuss the proposed mechanism and describe why it cannot apply to ectotherms. Despite this, we encourage a thorough investigation of the mechanisms responsible for maintaining Bergmann's pattern in ectotherms and support Olalla‐Tárraga's quest for a unifying mechanism to explain body size gradients in endotherms and ectotherms.
Mental health‐related learning needs of clinicians working in Australian emergency departments: A national survey of self‐reported confidence and knowledge
Authors: Sivakumar Sharanya , Weiland Tracey J , Gerdtz Marie F , Knott Jonathon , Jelinek George A
Published: August 2011

Objective: To identify the mental health‐related learning needs of doctors and nurses working in Australian EDs.

Methods: A purpose‐designed survey was developed, and face validity was verified by 12 doctors and nurses. A cross‐sectional survey of a national sample of nurses and senior doctors (registrars and consultants) working in EDs across Australia was then undertaken. The survey consisted of 130 items and required approximately 20 min for completion. The survey was delivered online through email invitation by the College of Emergency Nurses Australasia or the Australasian College for Emergency Medicine. A hardcopy format of the survey was also delivered at a national conference.

Results: Mental health presentations that involved a diagnosis of personality disorder, psychosis or behavioural disturbance, and the management of these conditions were patient factors that were considered problematic by up to 46.3% (118/255; 95% CI 40.26–52.40) of doctors and 66.1% (72/109; 95% CI 56.74–74.28) of nurses. Determining care plans, conducting mental status examinations, assessing risk of self‐harm, pharmacology for treatment and for chemical restraint, management of patient aggression or violence, and alcohol or drug intoxication were also found to be areas of knowledge deficit.

Conclusion: Doctors and nurses reported deficits in confidence and knowledge in tasks and patient presentations that they might frequently be expected to manage. These data can be used to inform future curricula at both undergraduate and postgraduate levels. Ultimately, this might pave the way for improved care and management of patients with mental health problems presenting to the ED.
Resolving the nuclear dust distribution of the Seyfert 2 galaxy NGC 3081
Authors: Ramos Almeida C. , Sánchez-Portal M. , Pérez García A. M. , Acosta-Pulido J. A. , Castillo M. , Asensio Ramos A. , González-Serrano J. I. , Alonso-Herrero A. , Rodríguez Espinosa J. M. , Hatziminaoglou E. , Coia D. , Valtchanov I. , Pović M. , Esquej P. , Packham C. , Altieri B.
Published: August 2011

We report far-infrared (FIR) imaging of the Seyfert 2 galaxy NGC 3081 in the range 70–500 µm, obtained with an unprecedented angular resolution, using the Herschel Space Observatory instruments PACS and SPIRE. The 11 kpc (∼70 arcsec) diameter star-forming ring of the galaxy appears resolved up to 250 µm. We extracted IR (1.6–500 µm) nuclear fluxes, that is active nucleus-dominated fluxes, and fitted them with clumpy torus models, which successfully reproduce the FIR emission with small torus sizes. Adding the FIR data to the near- and mid-IR spectral energy distribution (SED) results in a torus radial extent of Ro= 4+2− 1 pc, as well as in a flat radial distribution of the clouds (i.e. the q parameter). At wavelengths beyond 200 µm, cold dust emission at T= 28 ± 1 K from the circumnuclear star-forming ring of 2.3 kpc (∼15 arcsec) in diameter starts making a contribution to the nuclear emission. The dust in the outer parts of the galaxy is heated by the interstellar radiation field (19 ± 3 K).
Clastogenic Plasma Factors in Psoriasis—Comparison of Phototherapy and Anti–TNF‐α Treatments
Authors: Emerit Ingrid , Antunes Joana , Silva João Maia , Freitas João , Pinheiro Teresa , Filipe Paulo
Published: August 2011

As previously described, Psoralen plus UVA (PUVA) therapy induces chromosome damage in psoriatic patients. This study evaluates whether these effects are transitory or persistent. In addition, we studied these effects after narrowband UVB (nUVB) and anti‐tumor necrosis factor (TNF)‐α treatments. Among 40 responder patients, 10 received PUVA, 10 nUVB, 10 Infliximab and 10 Etanercept. Disease activity was determined with Psoriasis Area and Severity Index. Chromosomal breakage was evaluated by the clastogenic factor (CF) test. Potential clastogenic agents, malondialdehyde (MDA) and TNF‐α were measured. Before treatment, the plasma‐adjusted clastogenic scores (ACS) of patients were increased. During treatment, a further increase in ACS was observed in both phototherapy groups. Chromosome damage persisted for PUVA patients at week 32, while it diminished after nUVB to ACS values lower than before treatment. MDA and TNF‐α values were also increased at baseline. MDA decreased during treatment in all groups, but without reaching normal levels. Plasma TNF‐α remained unchanged in PUVA and nUVB but decreased in both anti–TNF‐α treatment groups. Psoriasis is accompanied by CF‐induced chromosomal breakage that increases during PUVA and nUVB treatments. Plasma clastogenic activity persisted in the follow‐up after PUVA, while after nUVB ACS returned to values even lower than baseline. Clastogenic activity during the induction phase with anti–TNF‐α remained unchanged.
Public Understanding of Cognitive Neuroscience Research Findings: Trying to Peer Beyond Enchanted Glass
Authors: Grotzer Tina A.
Published: August 2011

This article considers the appeal of cognitive neuroscience research to the general public within the context of the deep puzzles involved in using our minds to understand how our minds work. It offers a few promising examples of findings that illuminate the ways of the mind and reveal these workings to be counter‐intuitive with our subjective experience. However, this promise is tempered by the powerful role that perception, attention, and cognition play in how we reason about evidence. It argues that the interplay between what we believe about the nature of our minds and what the findings suggest constitutes a primary challenge in encouraging public understanding of cognitive neuroscience findings.
Histopathological changes after deep anterior lamellar keratoplasty using the ‘big‐bubble technique’
Authors: Braun Joachim M. , Hofmann‐Rummelt Carmen , Schlötzer‐Schrehardt Ursula , Kruse Friedrich E. , Cursiefen Claus
Published: August 2011

Purpose:  During deep anterior lamellar keratoplasty (DALK), endothelium and Descemet’s membrane are separated from the corneal stroma by intrastromal air injection (‘big‐bubble technique’). The aim of our study is to analyse histopathological changes in host corneal tissue caused by air insufflation in patients with keratoconus, their variability in 10 patients and their possible clinical implication.

Methods:  The excised anterior corneal lamellae of 10 patients with keratoconus having undergone DALK using the ‘big‐bubble technique’ were analysed by light and transmission electron microscopy as well as immunohistochemistry. In addition, intrastromal air accumulations were quantified morphometrically.

Results:  Intrastromal air was detected in all examined excised lamellae (8% of stromal volume), but with large variability (SD 8.8). It was detected preferentially in the inner layer of the corneal stroma and represented there up to 39% of the stromal volume. In addition, the air was predominantly located at one periphery of the excised lamellae. Intrastromal air bubbles were larger in the inner than in the superficial stromal layer and characterized by round shape and a CD68‐negative collagenous ‘pseudocapsule’. We detected no air‐injection‐induced alterations in Bowman’s layer and epithelium.

Conclusion:  Our results show that ‘big‐bubble DALK’ causes significant intrastromal air accumulations in the cornea. Pathologists should be conscious of this phenomenon and the high topographic variability. Intrastromal air in the recipient rim may be accompanied by a decrease in mechanical stability and could contribute to postoperative suture loosening.
Dental attendance of oral and oropharyngeal cancer patients in a public hospital in Western Australia
Authors: Frydrych AM , Slack‐Smith LM
Published: August 2011

Background:  Dentists have recently seen the introduction of devices which aim to facilitate early oral cancer detection, sparking interest in opportunistic oral cancer screening. However, concerns have been raised about the lack of regular dental attendance amongst high risk individuals. The purpose of this study was to obtain information pertaining to dental attendance of oral and oropharyngeal cancer patients.

Methods:  All records of patients referred to the Oral Medicine Clinic at the Oral Health Centre of Western Australia, between January 2005 and December 2009, from one major teaching hospital were examined. Information extracted included age, gender, smoking status, referral date, tumour type, tumour site, disease stage (TNM classification), and information on dental attendance. Outcomes measured included time (months) since the patient’s last dental visit and information concerning regularity of dental attendance.

Results:  No association was found between dental attendance and gender, smoking, disease stage or age at diagnosis. Most patients had not visited a dentist in the preceding 12 months. The mean date of last dental visit was 5.6 years prior.

Conclusions:  More should be done in Australia to encourage patients at high risk of oral cancer to attend the dentist and undergo annual oral soft tissue examination.
Pleomorphic adenoma of the buccal salivary gland: magnetic resonance imaging findings with differential diagnoses
Authors: Sharma Neeraj
Published: August 2011

The majority of minor salivary gland tumors are malignant. Of the benign tumors, pleomorphic adenomas are most common. The cheeks, lips, and gingiva are rarely sites of occurrence. A case of pleomorphic adenoma of the buccal salivary gland is presented here with a discussion of the importance of magnetic resonance imaging in demonstrating the extent of the lesion and establishing a differential diagnoses.
Conjugate Heat Transfer Within a Heterogeneous Hierarchical Structure
Authors: Catton Ivan
Published: August 2011

Optimization of heat exchangers (HE), compact heat exchangers (CHE) and microheat exchangers, by design of their basic structures is the focus of this work. Consistant models are developed to describe transport phenomena in a porous medium that take into account the scales and other characteristics of the medium morphology. Equation sets allowing for turbulence and two temperature or two concentration diffusion are obtained for nonisotropic porous media with interface exchange. The equations differ from known equations and were developed using a rigorous averaging technique, hierarchical modeling methodology, and fully turbulent models with Reynolds stresses and fluxes in the space of every pore. The transport equations are shown to have additional integral and differential terms. The description of the structural morphology determines the importance of these terms and the range of application of the closure schemes. A natural way to transfer from transport equations in a porous media with integral terms to differential equations with coefficients that could be experimentally or numerically evaluated and determined is described. The relationship between computational fluid dynamics, experiment and closure needed for the volume averaged equations is discussed. Mathematical models for modeling momentum and heat transport based on well established averaging theorems are developed. Use of a “porous media” length scale is shown to be very beneficial in collapsing complex data onto a single curve yielding simple heat transfer and friction factor correlations. The general transport equations developed for a single phase fluid in a heat exchange medium have many more integral and differential terms than the homogenized or classical continuum mechanics equations. Once these terms are dealt with by closure, the resulting equation set is relatively simple and their solution is obtained using simple numerical methods quickly enough for multiple parameter optimization using design of experiment or genetic algorithms. Current efforts to significantly improve the performance of an HE for electronic cooling, a two temperature problem, and of a finned tube heat exchanger, a three temperature problem, are described.
Lensed Plastic Optical Fiber with a Convexo-Concave Fiber Endface for Coupling Laser Diodes With Plastic Optical Fiber
Authors: Tseng Yih-Tun , Chang Shu-Ming , Huang Sheng-He , Cheng Wood-Hi
Published: August 2011

This work presents a novel lensed plastic optical fiber (POF), efficiently coupled with a light source. A convexo-concave plastic lens (CCPL) was bound to a flat-end plastic optical fiber using laser transmission welding (LTW) to form a convexo-concave-shaped fiber endface (CCSFE). The novel lensed plastic optical fiber has a longer working distance and a higher coupling efficiency than conventional lensed plastic optical fibers. 850 nm fiber is often used in high-power 2.5 Gb/s transmission rate. Experimental POF is perfluorinated POF, 62.5–500 μm diameter, 850∼1300 μm wavelength, 10 dB/km power loss rate, 2.5 Gb/s transmission rate. Because of the small diameter of POF, it is difficult to couple between the light source and POF. Therefore, it is important to develop a lensed fiber structure to increase the coupling efficiency. Experiments indicate that the coupling efficiency between a laser diode at a wavelength of 850 nm and a graded-index POF is as high as 85% with a long working distance of 250 μm. The measured tolerance, in relation to the lateral and vertical displacements and tilt, are satisfactory for practical active alignment.
Experimental
Investigation of Fouling Behavior of 90/10 Cu/Ni Tube by Heat Transfer Resistance Monitoring
Method
Authors: Izadi M. , Aidun D.
K. , Marzocca P. , Lee H.
Published: August 2011

This paper describes an advanced monitoring system for fouling phenomenon in a wide range of tubular heat exchangers such as condensers and intercoolers. First, a mathematical model of fouling resistance in tubular heat exchangers is adapted. The model is based on the applied thermal power, the inside heat transfer coefficient, and geometrical characteristics of the heat exchanger under consideration. The resulting model is a function of measured quantities such as water and tube wall temperatures, fluid flow velocity, and some physical properties of the fluid flowing inside the tubes, such as viscosity, conductivity, and density. Second, an on-line fouling monitoring system was prepared, and the heat transfer resistance for selected solutions was measured in real time by this system. The effect of concentration and chemical reactions on fouling was studied experimentally using contaminants such as sodium bicarbonate, sodium chloride, calcium chloride, and a mixture of sodium bicarbonate and calcium chloride. Experimental results provide quantitative information of liquid-side fouling on heat transfer surfaces, and its effects on the thermal efficiency. Experimental data are critical for heat exchanger design and for planning operating and cleaning schedules of the heat exchanger. Uncertainty analysis shows that the experimental results are acceptable and the experimental setup is appropriate for measuring fouling resistance in industrial applications.
An Investigation of a Tunable Magnetomechanical Thermal Switch
Authors: Bulgrin Katherine E. , Ju Y. Sungtaek , Carman Greg P. , Lavine Adrienne S.
Published: August 2011

We propose a new device-level concept for a thermal switch that exploits the temperature dependence of the magnetization of a ferromagnetic material oscillating between a hot and a cold surface. A numerical model is constructed to examine the operation of the thermal switch. The switch turn-on temperature can be readily tuned by adjusting physical parameters of the device, such as the gap between the hot and cold surfaces and the spring constant of the structure supporting the ferromagnet. Experimentally determined oscillation frequencies are consistent with the model predictions. Additionally, it is shown that the thermal contact conductance has a large influence on the device performance. The time-averaged heat flux and effective conductance compare favorably to existing thermal switch technologies over a range of hot surface temperatures.
Characterization and Modeling of the Heat Transfer Performance of Nanostructured Cu Micropost Wicks
Authors: Nam Youngsuk , Sharratt Stephen , Cha Gilhwan , Ju Y. Sungtaek
Published: August 2011

Micro heat pipes incorporating advanced wicks are promising for the thermal management of power electronics. We report the heat transfer performance of superhydrophilic Cu micropost wicks fabricated on thin silicon substrates using electrochemical deposition and controlled chemical oxidation. For a fixed post diameter, the interpost spacing and hence solid fraction is found to be a main design factor affecting the effective heat transfer coefficient and critical heat flux. The effective heat transfer coefficient >10 W/cm2 K and the critical heat flux >500 W/cm2 over 2 mm × 2 mm heating areas are demonstrated. Copper oxide nanostructures formed on the micropost surfaces significantly enhance the critical heat flux without compromising the effective heat transfer coefficient. An approximate numerical model is developed to help interpret the experimental data. A surface energy minimization algorithm is used to predict the static equilibrium shape of a liquid meniscus, which is then imported into a finite element model to predict the effective heat transfer coefficient. The advanced wick structures and experimental and modeling approaches developed in this work will help develop thin and lightweight thermal management solutions for high-power-density semiconductor devices.
Heat Transfer and Flow Resistance Characteristics of Louver Fin Geometry for Automobile Applications
Authors: Chan Kang Hie , Jun Gil Woong
Published: August 2011

The present work was conducted to investigate the air-side pressure drop and heat transfer performance of the louver fin-tube heat exchanger for automobile applications. Fourteen kinds of louver fin geometries with different louver pitches and angles were tested in the present work. The f and j factors for plane and louver fin configurations were compared experimentally and numerically. The heat transfer and pressure drop characteristics of the plane fin showed the combined mode of the developing flow on a flat plate and the fully developed flow in the rectangular channel. The heat transfer coefficient of the louver fin was about twice as high as that of the plane fin. Empirical correlations proposed by previous researchers were compared with the present experimental data. Correlations of j and f factors were proposed for the present experimental data. The j and f factors were simply expressed as functions of the average louver pitch, fin pitch, louver angle, and Reynolds number based on the louver pitch. The present correlations of the heat transfer and pressure drop agreed well with the experimental data.
Analysis of Residual Stresses in Sustainable Cryogenic Machining of Nickel Based Alloy—Inconel 718
Authors: Kenda Jani , Pusavec Franci , Kopac Janez
Published: August 2011

In machining processes, surface integrity is a major quality-related performance output. In the case of difficult-to-cut materials, this frequently relates to residual stresses induced in the machined surface and subsurface. As cryogenic machining presents a sustainable alternative to conventional machining processes, in this work, cryogenic machining and the influence of cooling/lubrication conditions on the surface integrity generated during turning of Inconel 718 are presented. The results show that the cryogenic machining process generates larger compressive residual stresses, and prevail at deeper levels beneath the machined surface, thus resulting in improved product quality and performance characteristics in terms of fatigue life and wear resistance.
Predicting the Effects of Cutting Parameters and Tool Geometry on Hard Turning Process Using Finite Element Method
Authors: Zhang Xueping , Wu Shenfeng , Wang Heping , Liu C. Richard
Published: August 2011

To explore the effects of cutting speed, feed rate and rake angle on chip morphology transition, a thermomechanical coupled orthogonal (2-D) finite element (FE) model is developed, and to determine the effects of tool nose radius and lead angle on hard turning process, an oblique (3-D) FE model is further proposed. Three one-factor simulations are conducted to determine the evolution of chip morphology with feed rate, rake angle, and cutting speed, respectively. The chip morphology evolution from continuous to saw-tooth chip is described by means of the variations of chip dimensional values, saw-tooth chip segmental degree and frequency. The results suggest that chip morphology transits from continuous to saw-tooth chip with increasing feed rate and cutting speed, and changing a tool’s positive rake angle to negative rake angle. There exists a critical cutting speed at which the chip morphology transfers from continuous to saw-tooth chip. The saw-tooth chip segmental frequency decreases as the feed rate and the tool negative rake angle value increases; however, it increases almost linearly with the cutting speed. The larger negative rake angle, the larger feed rate and higher cutting speed dominate saw-tooth chip morphology while positive rake angle, small feed rate and low cutting speed combine to determine continuous chip morphology. The 3-D FE model considers tool nose radii of 0.4 mm and 0.8 mm, respectively, with tool lead angels of 0 deg and 7 deg. The model successfully simulates 3-D saw-tooth chip morphology generated by periodic adiabatic shear and demonstrates the continuous and saw-tooth chip morphology, chip characteristic line and the material flow direction between chip-tool interfaces. The predicted chip morphology, cutting temperature, plastic strain distribution, and cutting forces agree well with the experimental data. The oblique cutting process simulation reveals that a bigger lead angle results in a severer chip deformation, the maximum temperature on the chip-tool interface reaches 1289 deg, close to the measured average temperature of 1100 deg; the predicted average tangential force is 150N, with 7% difference from the experimental data. When the cutting tool nose radius increases to 0.8 mm, the chip’s temperature and strain becomes relatively higher, and average tangential force increases 10N. This paper also discusses reasons for discrepancies between the experimental measured cutting force and that predicted by finite element simulation.
Experimental demonstration of hybrid CMOS-single electron transistor circuits
Authors: Prager Aaron A. , George Hubert C. , Orlov Alexei O. , Snider Gregory L.
Published: August 2011

This article presents a proof-of-concept integration of single electron transistors (SETs) and CMOS devices on a single substrate. Two different complementary metal-oxide-semiconductor (CMOS) voltage amplifiers were designed and fabricated for SET readout: a p-type metal-oxide-semiconductor (PMOS) linear amplifier with off-chip source and drain resistors, and a CMOS inverter, which provides gain with no external components. In both cases, the amplifier was coupled to a SET situated on the same substrate and tested at 1.1 K. The amplifiers must have minimal power dissipation to avoid overheating of the SET. Testing of both the linear and CMOS amplifiers demonstrated amplification of the voltage output of an SET/resistor voltage divider. Coulomb blockade of current in the I-V characteristic of SET and Coulomb blockade oscillations were observed with these amplifiers, demonstrating proof-of-concept of the use of CMOS and SETs together. This may enable future integration of CMOS technology with quantum-dot cellular automata or other novel device and logic types that use SETs for readout.
Image noise in helium lithography
Authors: Roy Ananya , Craver Barry , Ocola Leonidas E. , Wolfe John C.
Published: August 2011

A distinctive feature of resist exposure by energetic helium ions or neutral atoms is that critical exposure densities are very low, about 100 times smaller than for electrons. Thus, particle distributions are sparse, leading to significant statistical fluctuations in the deposited energy density even in polymethylmethacrylate (PMMA), a relatively insensitive, nonchemically amplified resist. The impact is first seen as roughness in the region of partial exposure on a feature’s edge where the bunching of just a few particles may cause the energy density to shift above or below the resist development threshold. As feature size is reduced, however, fluctuations in the total number of particles (shot noise) become larger as a fraction of average dose, potentially causing over- and underexposure of the entire feature. This article presents an integrated study of image noise in helium lithography that compares shape variations in neutral particle mask images with the predictions of a Monte Carlo model. The model accounts for the following: (1) Poisson statistics of the particle emission process, (2) the variable spatial distribution of the particles within the aerial image, (3) the effect of scattering on the particle distribution at various depths in the resist, and (4) smoothing of the deposited energy distribution by exposure and development processes. Proximity lithography experiments were carried out using 10 keV neutral helium atoms in 20 nm thick PMMA resist under conditions of 12.7 nm [full width at half maximum (FWHM)] penumbral image blur. The energy smoothing function is assumed, based on previous experiments, to be Gaussian and its standard deviation σ treated as a free parameter. Model predictions of the power spectral density of line edge roughness agree with experiment for σ=5.0±0.5 nm. The model predicts that using a resist with a critical dose 20 times higher than PMMA and reducing penumbra to 0.5 nm (FWHM), for example by reducing the proximity gap, would reduce shape fluctuations to less than 0.5 nm (FWHM) for dense 10 nm dot arrays.
Simulation studies of the dielectric layer effect on the discharge characteristics of the shadow mask plasma display panel
Authors: Zhang Panpan , Tu Yan , Yang Lanlan
Published: August 2011

The shadow mask plasma display panel, developed from the alternating current matrix plasma display panel, possesses several interesting features such as a simple manufacturing process, low cost, and short response time. The discharge process in cells with different dielectric layer thicknesses and relative permittivities at the same driving voltage was simulated based on a particle-in-cell/Monte Carlo collision model. It was found that the discharge characteristics were improved with an increase in the relative permittivity and a reduction in the dielectric layer thickness. The mechanism used in this phenomenon was analyzed theoretically and verified further by simulation, using different driving voltages. The results imply that the luminous efficacy can be improved either by reducing the relative permittivity or by increasing the thickness of the dielectric layer.
Low fluctuation and drift of field emission currents emitted from Pd/W nanotips
Authors: Akamine Yuta , Fujiwara Kazuto , Oshima Chuhei , Cho Boklae
Published: August 2011

The authors have observed the fluctuation and drift of field emission (FE) current from nanotips fabricated by the deposition of Pd under extreme high vacuum and subsequent annealing at ∼1000 K. Observed fluctuations of 0.02%–1% for 100 h at ∼10 nA were extremely low when compared with those of conventional FE guns (a few percent). From a practical point of view, drifts in FE current were negligible over several hours. When the Pd layer had been removed by repeated heating and FE operation, Pd redeposition on the tip apex was necessary for their restoration.
Interface stability in stressed solid-phase epitaxial growth
Authors: Morarka S. , Jin S. , Rudawski N. G. , Jones K. S. , Law M. E. , Elliman R. G.
Published: August 2011

The role of applied stress on interface stability during Si solid-phase epitaxial growth was investigated. Transmission electron microscopy observations of growth interface evolution revealed in-plane uniaxial compression (tension) led to interface instability (stability). Additionally, level set simulations revealed that the stress-influenced interface instability was accurately modeled by adjusting the strength of the linear dependence of local interface velocity (rate of change of interface position with respect to time) on local interface curvature proposed in previous work. This behavior is explained in terms of tension in the growth interface controlling interface stability during growth; it is argued that compressive (tensile) stress tends to reduce (enhance) interfacial tension and results in interfacial instability (stability) during growth.
Kelvin probe force microscopy-based characterization techniques applied for electrostatic MEMS/NEMS devices and bare dielectric films to investigate the dielectric and substrate charging phenomena
Authors: Zaghloul Usama , Bhushan Bharat , Coccetti Fabio , Pons Patrick , Plana Robert
Published: August 2011

In this study, two different characterization techniques based on Kelvin probe force microscopy (KPFM) have been used to investigate the dielectric and substrate charging in electrostatic micro- and nano-electromechanical systems (MEMS and NEMS). The first technique (KPFM-MEMS) has been employed to study the discharging process on a microscopic scale in a charged MEMS dielectric film. This has been performed by monitoring the surface potential decay with time of charged PECVD silicon nitride films implemented in electrostatic capacitive MEMS switches. The second methodology, KPFM-thin films (KPFM-TF), has been applied to investigate the charging/discharging processes in bare SiNx films as well as the substrate charging phenomenon. It makes use of the atomic force microscope tip to simulate charge injection through a single asperity, and then measure the induced surface potential. The influence of the SiNx film thickness and deposition conditions has been studied. Moreover, the impact of bias amplitude and bias polarity applied during charge injection has been explored. Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy material characterization techniques have been used to determine the chemical bonds and compositions, respectively, of the SiNx films being investigated. The nanoscale KPFM results obtained in this study reveal an accurate understanding of both the dielectric charging and the substrate charging that take place in electrostatic MEMS/NEMS devices.