bluuebunny/crossref_metadata_2025 huggingface dataset:
Prevalence of Electrocardiographic Findings Suggestive of Sudden Cardiac Death Risk in 10,867 Apparently Healthy Young Korean Men
Authors: UHM JAE‐SUN , HWANG IL‐UNG , OH YONG‐SEOG , CHOI MIN‐SEOK , JANG SUNG‐WON , SHIN WOO‐SEUNG , KIM JI‐HOON , LEE MAN‐YOUNG , RHO TAI‐HO , KIM YOU‐HO , SUNG JUNG‐HOON , LEE YOUNG‐SOO , CHO JEONG‐GWAN , OH DONG‐JIN , KIM DAE‐KYEONG , NAMGUNG JUNE , PARK KYOUNG‐MIN , KIM YONG‐HOON , KIM YOON‐NYUN , LIM HONG‐EUY , CHA TAE‐JOON , ON YOUNG‐KEUN , SHIN DONG‐GU , PAK HUI‐NAM , KIM NAM‐HO
Published: February 2011

Background:
 The objective of this study was to determine the prevalence of electrocardiographic (ECG) findings suggestive of sudden cardiac death risk in apparently healthy young Korean men.

Methods:
 We administered questionnaires that elicited personal and family histories and performed ECGs on 10,867 male subjects (mean age, 20.9 years). The subjects with abnormal ECG findings underwent echocardiography, a treadmill test, Holter monitoring, a flecainide provocation test, or an electrophysiologic study (EPS) according to the ECG findings and histories.

Results:
 Of the subjects, 5.95% had left ventricular hypertrophy on ECG, but no subjects had hypertrophic cardiomyopathy by echocardiography. The percentage of subjects with a Brugada ECG pattern was 0.90%. We identified one subject with a positive result on the flecainide provocation test. The percentage of subjects with a preexcitation ECG was 0.17%. In two of the subjects, supraventricular tachycardia was induced in the EPS. Of the subjects, 0.05% had epsilon waves, but there were no subjects with arrhythmogenic right ventricular dysplasia/cardiomyopathy by echocardiography. The percentage of subjects with long QT intervals was 0.02%, but there were no arrhythmias on the treadmill test or Holter monitoring.

Conclusions:
 The prevalence of a Brugada ECG pattern in apparently healthy young men is higher in Korea than other countries. (PACE 2011; 717–723)
Chronic Mitral Regurgitation: Left Atrial Deformation Analysis by Two‐Dimensional Speckle Tracking Echocardiography
Authors: Cameli Matteo , Lisi Matteo , Giacomin Elisa , Caputo Maria , Navarri Romina , Malandrino Angela , Ballo Piercarlo , Agricola Eustachio , Mondillo Sergio
Published: February 2011

Background: Speckle tracking echocardiography (STE) is a novel method for the angle‐independent and objective quantification of myocardial deformation; it has recently evolved, enabling the quantification of longitudinal myocardial left atrial (LA) deformation dynamics. To investigate the effects of chronic mitral regurgitation (MR) on these functional atrial indices, we analyzed LA function by STE in a group of asymptomatic patients with chronic degenerative MR. Methods: The study population included 36 patients with mild MR, 38 with moderate MR, and 42 with severe MR. 52 age‐matched controls were also recruited. Global peak atrial longitudinal strain (global PALS) was measured in all subjects by averaging all atrial segments. Results: Age, gender, and LV ejection fraction in all pathological groups were comparable to those in the controls. Global PALS was higher in the mild MR group (46.7 ± 9.1%) in comparison with the controls (40.5 ± 6.2%; P < 0.001); instead global PALS was lower in the moderate MR group (25.7 ± 7.1%) and further reduced in the severe MR group (13.2 ± 5.2%) in comparison with the controls (40.5 ± 6.2%; overall P < 0.0001 by ANOVA, P < 0.05 for all pairwise comparisons). In multivariate analysis, E/Em ratio emerged as the principal independent determinant of global PALS. Conclusions: Our study provides new insight for the LA function analysis in response to different degrees of MR, showing that STE measurements of LA longitudinal strain may be considered a promising tool for the early detection of impairment of LA compliance in patients with asymptomatic chronic MR. (Echocardiography 2011;28:327‐334)
Contributing to the Synergistic Circulation of Knowledge
Authors: Sargsyan‐Pittman Nelli
Published: February 2011

[field notes, circulation, reflexivity, ethnicity, gender, Armenian American]
X-ray and optical observations of the closest isolated radio pulsar
Authors: Tiengo A. , Mignani R. P. , De Luca A. , Esposito P. , Pellizzoni A. , Mereghetti S.
Published: February 2011

With a parallactic distance of 170 pc, PSR J2144–3933 is the closest isolated radio pulsar currently known. It is also the slowest (P= 8.51 s) and least energetic ( erg s−1) radio pulsar; its radio emission is difficult to account for with standard pulsar models, since the position of PSR J2144−3933 in the period–period derivative diagram is far beyond the typical radio ‘death lines’. Here we present the first deep X-ray and optical observations of PSR J2144−3933, performed in 2009 with XMM–Newton and European Southern Observatory (ESO)/Very Large Telescope (VLT), from which we derive, assuming a blackbody emission spectrum, a surface temperature upper limit of 2.3 × 105 K for a 13 km radius neutron star, 4.4 × 105 K for a 500 m radius hotspot and 1.9 × 106 K for a 10 m radius polar cap. In addition, our non-detection of PSR J2144−3933 constrains its non-thermal luminosity to be <30 and <2 per cent of the pulsar rotational energy loss in the 0.5–2 keV X-ray band and in the B optical band, respectively.
Dating the formation of the counter-rotating stellar disc in the spiral galaxy NGC 5719 by disentangling its stellar populations
Authors: Coccato L. , Morelli L. , Corsini E. M. , Buson L. , Pizzella A. , Vergani D. , Bertola F.
Published: February 2011

We present the results of the VLT/VIMOS integral-field spectroscopic observations of the inner 28 × 28 arcsec2 (3.1 × 3.1 kpc2) of the interacting spiral NGC 5719, which is known to host two cospatial counter-rotating stellar discs. At each position in the field of view, the observed galaxy spectrum is decomposed into the contributions of the spectra of two stellar and one ionized-gas components. We measure the kinematics and the line strengths of the Lick indices of the two stellar counter-rotating components. We model the data of each stellar component with single stellar population models that account for the α/Fe overabundance. We also derive the distribution and kinematics of the ionized-gas disc, that is associated with the younger, less rich in metals, more α-enhanced, and less luminous stellar component. They are both counter rotating with respect the main stellar body of the galaxy. These findings prove the scenario where gas was accreted first by NGC 5719 on to a retrograde orbit from the large reservoir available in its neighbourhoods as a result of the interaction with its companion NGC 5713, and subsequently fuelled the in situ formation of the counter-rotating stellar disc.
Comparison of stochastic and fuzzy dynamic programming models for the operation of a multipurpose reservoir
Authors: Chandramouli Sangamreddi , Nanduri Umamahesh V.
Published: February 2011

Reservoir management is a highly complex problem, which includes the uncertainty in the inflows as well as in the objectives. Stochastic dynamic programming (SDP) has been widely used to develop the optimal operating policies of multipurpose reservoirs. In the recent years, fuzzy optimization has been used to incorporate the uncertainty caused due to the imprecise nature of objectives. In the present study, a comparison is made between a conventional SDP model and fuzzy dynamic programming models for optimal operation of a multipurpose reservoir. The two models are developed for Hirakud Reservoir on River Mahanadi in the State of Orissa in India. The performance of the reservoir is evaluated under the operating policies derived from these models through simulation. The results indicate that the fuzzy dynamic programming model performs better in achieving the flood control objective and thus in the overall performan1ce of reservoir.
The economic value of ecosystem services in the Great Barrier Reef: our state of knowledge
Authors: Stoeckl Natalie , Hicks Christina C. , Mills Morena , Fabricius Katharina , Esparon Michelle , Kroon Frederieke , Kaur Kamaljit , Costanza Robert
Published: February 2011

This article reviews literature relating to the Great Barrier Reef (GBR) and aims to assess the current state of knowledge about (1) the “value” of ecosystem services (ES) provided by the GBR and (2) the way in which activities that are carried out in regions adjacent to the GBR affect those values. It finds that most GBR valuation studies have concentrated on a narrow range of ES (e.g., tourism and fishing) and that little is known about other ES or about the social, temporal, and spatial distribution of those services. Just as the reef provides ES to humans and to other ecosystems, so too does the reef receive a variety of ES from adjoining systems (e.g., mangroves). Yet, despite the evidence that the reef's ability to provide ES has been eroded because of recent changes to adjoining ecosystems, little is known about the value of the ES provided by adjoining systems or about the value of recent changes. These information gaps may lead to suboptimal allocations of resource use within multiple realms.
Is steady‐state capitalism viable?
Authors: Lawn Philip
Published: February 2011

Most ecological economists believe that the transition to a steady‐state economy is necessary to ensure ecological sustainability and to maximize a nation's economic welfare. While some observers agree with the necessity of the steady‐state economy, they are nonetheless critical of the suggestion made by ecological economists—in particular, Herman Daly—that a steady‐state economy is compatible with a capitalist system. First, they believe that steady‐state capitalism is based on the untenable assumption that growth is an optional rather than in‐built element of capitalism. Second, they argue that capitalist notions of efficient resource allocation are too restrictive to facilitate the transition to an “ecological” or steady‐state economy. I believe these observers are outright wrong with their first criticism and, because they misunderstand Daly's vision of a steady‐state economy, are misplaced with their second criticism. The nature of a capitalist system depends upon the institutional framework that supports and shapes it. Hence, a capitalist system can exist in a wide variety of forms. Unfortunately, many observers fail to recognize that the current “growth imperative” is the result of capitalist systems everywhere being institutionally designed to grow. They need not be designed this way to survive and thrive. Indeed, because continued growth is both existentially undesirable and ecologically unsustainable, redesigning capitalist systems through the introduction of Daly‐like institutions would prove to be capitalism's savior. What's more, it would constitute humankind's best hope of achieving sustainable development.
Human‐induced morphological shifts in an island lizard
Authors: Marnocha Erin , Pollinger John , Smith Thomas B.
Published: February 2011

Understanding the evolutionary consequences of anthropogenic change is an emerging topic in evolutionary biology. While highly sensitive species may go extinct in response to anthropogenic habitat alteration, those with broader environmental tolerances may persist and adapt to the changes. Here, we use morphological data from the brown anole (Anolis sagrei), a lizard species that lives in both natural and human‐disturbed habitats, to examine the impact of anthropogenic habitat alteration. We find populations inhabiting disturbed habitats were significantly larger in snout‐vent length, hindspan, and mass and provide evidence that the observed divergence in hindspan is driven by human‐induced changes in habitat structure. Populations were found to be genetically distinct among islands but are not genetically differentiated between habitat types on islands. Thus, the observed pattern of intra‐island morphological differences cannot be explained by separate founding populations. Rather, our results are consistent with morphological differences between habitats having arisenin situon each island. Results underscore the significant impact anthropogenic change may have on evolutionary trajectories of populations that persist in human‐altered habitats.
BRAF mutations in cutaneous melanoma are independently associated with age, anatomic site of the primary tumor, and the degree of solar elastosis at the primary tumor site
Authors: Bauer Jürgen , Büttner Petra , Murali Rajmohan , Okamoto Ichiro , Kolaitis Nicholas A. , Landi Maria T. , Scolyer Richard A. , Bastian Boris C.
Published: February 2011

Oncogenic BRAF mutations are more frequent in cutaneous melanoma occurring at sites with little or moderate sun‐induced damage than at sites with severe cumulative solar ultraviolet (UV) damage. We studied cutaneous melanomas from geographic regions with different levels of ambient UV radiation to delineate the relative effects of cumulative UV damage, age, and anatomic site on the frequency of BRAF mutations. We show that BRAF‐mutated melanomas occur in a younger age group on skin without marked solar elastosis and less frequently affect the head and neck area, compared to melanomas without BRAF mutations. The findings indicate that BRAF‐mutated melanomas arise early in life at low cumulative UV doses, whereas melanomas without BRAF mutations require accumulation of high UV doses over time. The effect of anatomic site on the mutation spectrum further suggests regional differences among cutaneous melanocytes.
Introduction and clinical evaluation of servo‐controlled applanation resonance tonometry
Authors: Jóhannesson Gauti , Hallberg Per , Eklund Anders , Lindén Christina
Published: February 2011

Purpose:  In recent years, Applanation Resonance Tonometry (ART) has been suggested for intraocular pressure (IOP) measurements. The manual version of ART (ARTmanual) has been further developed, and to improve usability, an automatic servo‐controlled prototype (ARTservo) has been proposed. The aim of this study was to assess the limits of agreement (LoA) of ARTmanual and ARTservo as compared with the reference method, Goldmann Applanation Tonometry (GAT).

Methods:  This was a prospective single‐centre study on 152 eyes from 77 subjects. It was designed according to International Standard Organization’s (ISO) requirements for tonometers (ISO 2001). Intraocular pressure was measured six times/method in a standardized order. The ART technique has two available analysis procedures: a dynamic one that measures IOP during the indentation phase and a static one that causes a Goldmann‐like measurement during two seconds of full applanation. The 95% LoA was defined as ±1.96 × standard deviation of difference against GAT.

Results:  Mean IOP for GAT was 19.1 mmHg (range: 10–37 mmHg). The 95% LoA of ARTmanual was ±4.5 mmHg for both dynamic and static analyses. The 95% LoA of ARTservo was ±5.7 mmHg for dynamic and ±4.9 mmHg for static analyses.

Conclusions:  This study confirms that the ART methodology is feasible. The further developed ARTmanual fulfilled the ISO standard with both the dynamic and the static analysis techniques. ARTservo with static analysis was close to fulfilling the standard but failed to do so in the highest IOP range. ARTservo has the potential to greatly improve usability if further development is completed.
Relationship between Urological Disease and Inferior Vena Cava Reflux on Color Doppler Ultrasonography
Authors: SUGAYA Kimio , MATSUMURA Eiri , TASAKI Shinsuke , KIMURA Ryu , KIYUNA Asuka , NISHIJIMA Saori , KADEKAWA Katsumi
Published: February 2011

Objectives: The possible relationship between urological disease and inferior vena cava (IVC) reflux was examined.

Methods: Transabdominal color Doppler ultrasonography of the IVC was performed. The patient was placed supine and the convex probe was positioned in vertical to the upper abdominal wall. Then the extent of reflux in the IVC accompanying each heart beat was examined near the diaphragm. A total of 403 patients (202 males and 201 females aged 12–90 years) were studied. The relationship between the existence of IVC reflux or its severity and urological disease was examined.

Results: The 202 males included 104 and 98 subjects without and with IVC reflux, respectively, while the 201 females included 64 and 137 subjects without and with IVC reflux, respectively. The prevalence of IVC reflux was significantly higher in females than males. Chronic prostatitis (18/21 subjects) in males and stress incontinence (22/23 subjects) in females were significantly related to the existence of IVC reflux. Conversely, urolithiasis was related to lack of IVC reflux in females.

Conclusions: IVC reflux may be positively or negatively related to the occurrence of some urological diseases. Pelvic congestion secondary to IVC reflux may be one of the factors contributing to chronic prostatitis and stress incontinence.
The active methanotrophic community in a wetland from the High Arctic
Authors: Graef Christiane , Hestnes Anne Grethe , Svenning Mette Marianne , Frenzel Peter
Published: February 2011

The dominant terminal process of carbon mineralization in most freshwater wetlands is methanogenesis. With methane being an important greenhouse gas, the predicted warming of the Arctic may provide a positive feedback. However, the amount of methane released to the atmosphere may be controlled by the activity of methane‐oxidizing bacteria (methanotrophs) living in the oxic surface layer of wetlands. Previously, methanotrophs have been isolated and identified by genetic profiling in High Arctic wetlands showing the presence of only a few genotypes. Two isolates from Solvatnet (Ny‐Ålesund, Spitsbergen; 79°N) are available: Methylobacter tundripaludum (type I) and Methylocystis rosea (type II), raising the question whether the low diversity is a cultivation effect. We have revisited Solvatnet applying stable isotope probing (SIP) with 13C‐labelled methane. 16S rRNA profiling revealed active type I methanotrophs including M. tundripaludum, while no active type II methanotrophs were identified. These results indicate that the extant M. tundripaludum is an active methane oxidizer at its locus typicus; furthermore, Methylobacter seems to be the dominant active genus. Diversity of methanotrophs was low as compared, e.g. to wetland rice fields in the Mediterranean. This low diversity suggests a high vulnerability of Arctic methanotroph communities, which deserves more attention.
How many adenocarcinoma lung cancers come from bronchioloalveolar carcinoma?
Authors: Wong Alvin S. , Seto Kar‐Yin , Ang Bertrand , Wong Eunice , Chin Tan‐Min , Nga Min‐En , Soo Ross A.
Published: February 2011

Background:  There is emerging evidence that bronchioloalveolar carcinoma (BAC) is the forerunner of peripheral adenocarcinoma lung cancers (ALC). Since advanced stage ALC is often diagnosed on cytology alone, we hypothesized that the incidence of BAC is underreported and that a large proportion of ALC in our population are part of the BAC‐adenocarcinoma sequence.

Methods:  We reviewed the pretreatment computed tomographic (CT) scans of 69 patients with ALC and looked for characteristic features of BAC.

Results:  The median patient age was 63, and the majority were of Chinese descent (75.4%). Women comprised 43.5% of the patients (30 patients) and never‐smokers comprised 47.8% (33 patients). Only 15 patients (21.7%) had surgical specimens. The presence of BAC components was reported in the pathology of 16 patients (23.2%). CT features classically associated with BAC were found in 35 patients (50.7%). These included air bronchograms or bubble‐like lucencies in 24 patients (34.8%), ground‐glass opacities in 19 (27.5%), consolidation or pneumonic picture in 11 (15.9%), diffuse small or miliary nodules in 10 (14.5%), and the CT angiogram sign in 4 (5.8%).

Conclusions:  We found provocative radiologic evidence that a large proportion of our ALC cases arise from BAC. The CT findings are consistent with current understanding of the likely pathogenesis of peripheral ALC.
Reducing Surgical Ward Congestion Through Improved Surgical Scheduling and Uncapacitated Simulation
Authors: Chow Vincent S. , Puterman Martin L. , Salehirad Neda , Huang Wenhai , Atkins Derek
Published: February 2011

High surgical bed occupancy levels often result in heightened staff stress, frequent surgical cancellations, and long surgical wait times. This congestion is in part attributable to surgical scheduling practices, which often focus on the efficient use of operating rooms but ignore resulting downstream bed utilization. This paper describes a transparent and portable approach to improve scheduling practices, which combines a Monte Carlo simulation model and a mixed integer programming (MIP) model. For a specified surgical schedule, the simulation samples from historical case records and predicts bed requirements assuming no resource constraints. The MIP model complements the simulation model by scheduling both surgeon blocks and patient types to reduce peak bed occupancies. Scheduling guidelines were developed from the optimized schedules to provide surgical planners with a simple and implementable alternative to the MIP model. This approach has been tested and delivered to planners in a health authority in British Columbia, Canada. The models have been used to propose new surgical schedules and to evaluate the impact of proposed system changes on ward congestion.
Blocking in Healthcare Operations: A New Heuristic and an Application
Authors: Bretthauer Kurt M. , Heese H. Sebastian , Pun Hubert , Coe Edwin
Published: February 2011

We consider the problem of optimal capacity allocation in a hospital setting, where patients pass through a set of units, for example intensive care and acute care (AC), or AC and post‐acute care. If the second stage is full, a patient whose service at the first stage is complete is blocked and cannot leave the first stage. We develop a new heuristic for tandem systems to efficiently evaluate the effects of such blocking on system performance and we demonstrate that this heuristic performs well when compared with exact solutions and other approaches presented in the literature. In addition, we show how our tandem heuristic can be used as a building block to model more complex multi‐stage hospital systems with arbitrary patient routing, and we derive insights and actionable capacity strategies for a real hospital system where such blocking occurs between units.
When Should a Firm Open its Source Code: A Strategic Analysis
Authors: Kort Peter M. , Zaccour Georges
Published: February 2011

Deciding to open the source code of a software product has advantages and disadvantages. The disadvantage is that the firm loses the revenue from the software. The advantage is that the users' network can contribute to the quality of the software code, which increases the demand for the software and for a complementary product. Demand for the complementary product also goes up, because demand for a product increases when the price of its complement decreases, and under open source, the price of the software product drops down to zero. This paper examines the strategic interactions at work here, within a duopoly framework, and tries to determine the circumstances under which it is optimal for a firm to open its code. We find that firms open the source code when there is a competitive software‐product market, a less competitive complementary‐product market, and when the complementary product is of high quality. Furthermore, it is more profitable for the firm to open the source code if its competitor also does so. When this happens the incentive to open the code can even be higher than in a monopoly situation. More intense competition induces symmetric equilibria in which both firms choose the same strategy.
Refusals in Chinese: How Do L1 and L2 Differ?
Authors: Hong Wei
Published: February 2011

Abstract:This article reports on an empirical study of refusal strategies in Chinese by native speakers (NS) and nonnative Chinese learners (NNS). Sixty subjects (perceived as “students”) were to refuse an invitation by “the professor” to a Chinese New Year's party. The study found that the NS group produced 10 strategies, whereas the NNS group produced seven strategies. Among the total number of strategies, both groups favored the use of “apology” and “explanation” with similar frequency while differing in the choice of other strategies and their usage frequency. In direct refusals, the author noticed negative L1 (English) pragmatic transfer of NNS. The study found that L1 and L2 refusals in Chinese present fewer similarities and more differences, presumably due to the lack of L1 intercultural knowledge of L2 learners.
Narration and Narrative in L2 Speakers of Russian
Authors: Robin Richard M.
Published: February 2011

Abstract: The researcher examined 54 oral proficiency interviews (OPIs) with L2 Russian speakers ranging from Intermediate High through Superior (predominantly Advanced Mid) for narrative as defined by Labov. Descriptors adapted from episodic analysis were also used. While the author found that OPIs provided relatively weak prompts for narrative, Superior speakers provided complex episodes more readily than did speakers at lower levels. While the author found paragraphed narration throughout the Advanced range, narrative episodes consisted largely of stative accounts of events, often accompanied by evaluation, rather than punctual actions. Attempts at complete episodic narration at Advanced Mid and lower levels sometimes resulted in evidence of additional cognitive load or breakdown. The researcher concluded that narrative, as opposed to narration, is an emerging skill at the Advanced level.
The lunar rock and mineral characterization consortium: Deconstruction and integrated mineralogical, petrologic, and spectroscopic analyses of mare basalts
Authors: ISAACSON Peter J. , SARBADHIKARI Amit BASU , PIETERS Carlé M. , KLIMA Rachel L. , HIROI Takahiro , LIU Yang , TAYLOR Lawrence A.
Published: February 2011

Abstract–

The lunar rock and mineral characterization consortium (LRMCC) has conducted coordinated mineralogy/petrography/spectroscopy analyses of a suite of pristine lunar basalts. Four basalt slabs (two low‐Ti, two high‐Ti) and paired thin sections were analyzed. Thin sections were analyzed for mineralogy/petrography, while the slabs were used to prepare particulate separates of major mineral phases and bulk samples. Mineral separates and particulate bulk samples were crushed to controlled grain sizes and their reflectance spectra measured in the NASA RELAB at Brown University. The resulting data set provides an essential foundation for spectral mixing models, offers valuable endmember constraints for space weathering analyses, and represents critical new ground truth results for lunar science and exploration efforts.
Baby massage – what's not to like?
Authors: Huntley A , Procianoy RS , Mandes EW , Silveira RC
Published: February 2011

Procianoy RS, Mendes EW, Silverira RC.

Massage therapy improves neurodevelopment outcome at two years corrected for very low birth weight infants.

Early Hum Dev 2010; 86: 7–11.
Does acupuncture improve allergic symptoms in adults with atopic eczema?
Authors: Liu J
Published: February 2011

Pfab F, Huss‐Marp J, Gatti A Fuqin J, Athanasiadis GI, Irnich D, Raap U, Schober W, Behrendt H, Ring J, Darsow U.

Influence of acupuncture on type I hypersensitivity itch and the wheal and flare response in adults with atopic eczema – a blinded, randomized, placebo‐controlled, crossover trial.

Allergy 2010; 65: 903–10.
Glucosamine and chondroitin for osteoarthritis of the hip or knee
Authors: Ernst E
Published: February 2011

Wandel S, Jüni P, Tendal B, Nüesch E, Villiger PM, Welton NJ, Reichenbach S, Trelle S.

Effects of glucosamine, chondroitin, or placebo in patients with osteoarthritis of hip or knee: network meta‐analysis.

BMJ 2010; 341: c4675.
Glucosamine does not help those with back pain
Authors: Ernst E , Wilkens P
Published: February 2011

Wilkens P, Scheel IB, Grundnes O Hellum C, Storheim K.

Effect of glucosamine on pain‐related disability in patients with chronic low back pain and degenerative lumbar osteoarthritis: a randomized controlled trial.

JAMA 2010; 304: 45–52.
Acupressure may relieve pain, delivery time and oxytocin use during labour
Authors: Melchart D , Jack M , Kashanian M
Published: February 2011

Kashanian M, Shahali S.

Effects of acupressure at the Sanyinjiao point (SP6) on the process of active phase of labor in nulliparas women.

J Matern Fetal Neonatal Med 2010; 23: 638–1.
Therapeutic touch appears to reduce pain and fatigue in cancer patients
Authors: O'Mathúna DP
Published: February 2011

Aghabati N, Mohammadi E, Esmaiel ZP.

The effect of therapeutic touch on pain and fatigue of cancer patients undergoing chemotherapy.

Evid Based Complement Alternat Med 2010; 7: 375–81.
Computational Modeling of Three-Dimensional Endwall Flow Through a Turbine Rotor Cascade With Strong Secondary Flows
Authors: Ho Y.-H. , Lakshminarayana B.
Published: February 2011

A steady, three-dimensional Navier–Stokes solver that utilizes a pressure-based technique for incompressible flows is used to simulate the three-dimensional flow field in a turbine cascade. A new feature of the numerical scheme is the implementation of a second-order plus fourth-order artificial dissipation formulation, which provides a precise control of the numerical dissipation. A low-Reynolds-number form of a two-equation turbulence model is used to account for the turbulence effects. Comparison between the numerical predictions and the experimental data indicates that the numerical model is able to capture most of the complex flow phenomena in the endwall region of a turbine cascade, except the high gradient region in the secondary vortex core. The effects of inlet turbulence intensity and turbulence length scale on secondary vortices, total pressure loss, and turbulence kinetic energy inside the passage are presented and interpreted. It is found that higher turbulence intensity energizes the vortical motions and tends to move the passage vortex away from the endwall. With a larger turbulence length scale, the secondary flow inside the passage is reduced. However, the total pressure loss increases due to higher turbulence kinetic energy production.
Investigation of the Flow Field Downstream of a Turbine Trailing Edge Cooled Nozzle Guide Vane
Authors: Sieverding C. H. , Arts T. , De´nos R. , Martelli F.
Published: February 2011

A trailing edge cooled low aspect ratio transonic turbine guide vane is investigated in the VKI Compression Tube Cascade Facility at an outlet Mach number M2, is = 1.05 and a coolant flow rate m˙c/m˙g = 3 percent. The outlet flow field is surveyed by combined total-directional pressure probes and temperature probes. Special emphasis is put on the development of low blockage probes. Additional information is provided by oil flow visualizations and numerical flow visualizations with a three-dimensional Navier–Stokes code. The test results describe the strong differences in the axial evolution of the hub and tip endwall and secondary flows and demonstrate the self-similarity of the midspan wake profiles. According to the total pressure and temperature profiles, the wake mixing appears to be very fast in the near-wake but very slow in the far-wake region. The total pressure wake profile appears to be little affected by the coolant flow ejection.
A Design Study of Radial Inflow Turbines With Splitter Blades in Three-Dimensional Flow
Authors: Tjokroaminata W. D. , Tan C. S. , Hawthorne W. R.
Published: February 2011

An inverse design technique to design turbomachinery blading with splitter blades in three-dimensional flow is developed. It is based on the use of Clebsch transformation, which allows the velocity field to be written as a potential part and a rotational part. It is shown that the rotational part can be expressed in terms of the mean swirl schedule (the circumferential average of the product of radius and tangential velocity) and the blade geometry that includes the main blade as well as the splitter blade. This results in an inverse design approach, in which both the main and the splitter blade geometry are determined from a specification of the swirl schedule. Previous design study of a heavily loaded radial inflow turbine, without splitter blades, for a rather wide variety of specified mean swirl schedules results in a blade shape with unacceptable nonradial blade filament; the resulting reduced static pressure distribution yields an “inviscid reverse flow region” covering almost the first half of the blade pressure surface. When the inverse design technique is applied to the design study of the turbine wheel with splitter blades, the results indicate that the use of splitter blades is an effective means for making the blade filament at an axial location more radial as well as a potential means for eliminating any “inviscid reverse flow” region that may exist on the pressure side of the blades.
Detailed Stress Tensor Measurements in a Centrifugal Compressor Vaneless Diffuser
Authors: Pinarbasi A. , Johnson M. W.
Published: February 2011

Detailed flow measurements have been made in the vaneless diffuser of a large low-speed centrifugal compressor using hot-wire anemometry. The three time mean velocity components and full stress tensor distributions have been determined on eight measurement planes within the diffuser. High levels of Reynolds stress result in the rapid mixing out of the blade wake. Although high levels of turbulent kinetic energy are found in the passage wake, they are not associated with strong Reynolds stresses and hence the passage wake mixes out only slowly. Low-frequency meandering of the wake position is therefore likely to be responsible for the high kinetic energy levels. The anisotropic nature of the turbulence suggests that Reynolds stress turbulence models are required for CFD modeling of diffuser flows.
Thermal Management and Rotordynamic Performance of a Hot Rotor-Gas Foil Bearings System—Part I: Measurements
Authors: San Andrés Luis , Ryu Keun , Kim Tae Ho
Published: February 2011

Implementation of gas foil bearings (GFBs) into micro gas turbines requires careful thermal management with accurate measurements verifying model predictions. This two-part paper presents test data and analytical results for a test rotor and GFB system operating hot (157°C maximum rotor outer diameter (OD) temperature). Part I details the test rig and measurements of bearing temperatures and rotor dynamic motions obtained in a hollow rotor supported on a pair of second generation GFBs, each consisting of a single top foil (38.14 mm inner diameter) uncoated for high temperature operation and five bump strip support layers. An electric cartridge (maximum of 360°C) loosely installed inside the rotor (1.065 kg, 38.07 mm OD, and 4.8 mm thick) is a heat source warming the rotor-bearing system. While coasting down from 30 krpm to rest, large elapsed times (50–70 s) demonstrate rotor airborne operation, near friction free, and while traversing the system critical speed at ∼13 krpm, the rotor peak motion amplitude decreases as the system temperature increases. In tests conducted at a fixed rotor speed of 30 krpm, while the shaft heats, a cooling gas stream of increasing strength is set to manage the temperatures in the bearings and rotor. The effect of the cooling flow, if turbulent in character, is most distinctive at the highest heater temperature. For operation at a lower heater temperature condition, however, the cooling flow stream demonstrates a very limited effectiveness. The measurements demonstrate the reliable performance of the rotor-GFB system when operating hot. The test results, along with full disclosure on the materials and geometry of the test bearings and rotor, serve to benchmark a predictive tool. A companion paper (Part II) compares the measured bearing temperatures and the rotor response amplitudes to predictions.
Thermal Management and Rotordynamic Performance of a Hot Rotor-Gas Foil Bearings System—Part II: Predictions Versus Test Data
Authors: San Andrés Luis , Ryu Keun , Kim Tae Ho
Published: February 2011

Implementation of gas foil bearings (GFBs) in microgas turbines relies on physics based computational models anchored to test data. This two-part paper presents test data and analytical results for a test rotor and GFB system operating hot. A companion paper (Part I) describes a test rotor-GFB system operating hot to 157°C rotor OD temperature, presents measurements of rotor dynamic response and temperatures in the bearings and rotor, and includes a cooling gas stream condition to manage the system temperatures. The second part briefs on a thermoelastohydrodynamic (TEHD) model for GFBs performance and presents predictions of the thermal energy transport and forced response, static and dynamic, in the tested gas foil bearing system. The model considers the heat flow from the rotor into the bearing cartridges and also the thermal expansion of the shaft and bearing cartridge and shaft centrifugal growth due to rotation. Predictions show that bearings’ ID temperatures increase linearly with rotor speed and shaft temperature. Large cooling flow rates, in excess of 100 l/min, reduce significantly the temperatures in the bearings and rotor. Predictions, agreeing well with recorded temperatures given in Part I, also reproduce the radial gradient of temperature between the hot shaft and the bearings ID, largest (37°C/mm) for the strongest cooling stream (150 l/min). The shaft thermal growth, more significant as the temperature grows, reduces the bearings operating clearances and also the minimum film thickness, in particular, at the highest rotor speed (30 krpm). A rotor finite element structural model and GFB force coefficients from the TEHD model are used to predict the test system critical speeds and damping ratios for operation at increasing shaft temperatures. In general, predictions of the rotor imbalance show good agreement with shaft motion measurements acquired during rotor speed coastdown tests. As the shaft temperature increases, the rotor peak motion amplitudes decrease and the system rigid-mode critical speed increases. The computational tool, benchmarked by the measurements, furthers the application of GFBs in high temperature oil-free rotating machinery.
Application of Negligible Creep Criteria to Candidate Materials for HTGR Pressure Vessels
Authors: Jetter R. I. , Sham T.-L. , Swindeman R. W.
Published: February 2011

Two of the proposed high temperature gas reactors (HTGRs) under consideration for a demonstration plant have the design object of avoiding creep effects in the reactor pressure vessel during normal operation. This work addresses the criteria for negligible creep in subsection NH, Division 1 of the ASME Boiler and Pressure Vessel Code, Sec. III, other international design codes, and some currently suggested criteria modifications and their impact on permissible operating temperatures for various reactor pressure vessel materials. The goal of negligible creep could have different interpretations depending on what failure modes are considered and associated criteria for avoiding the effects of creep. It is shown that for the materials of this study, consideration of localized damage due to cycling of peak stresses results in a lower temperature for negligible creep than consideration of the temperature at which the allowable stress is governed by the creep properties. In assessing the effect of localized cyclic stresses, it is also shown that consideration of cyclic softening is an important effect that results in a higher estimated temperature for the onset of significant creep effects than would be the case if the material were cyclically hardening. There are other considerations for the selection of vessel material besides avoiding creep effects. Of interest for this review are (1) the material’s allowable stress level and impact on the wall thickness (the goal being to minimize the required wall thickness) and (2) ASME code approval (inclusion as a permitted material in the relevant section and subsection of interest) to expedite regulatory review and approval. The application of negligible creep criteria to two of the candidate materials, SA533 and Mod 9Cr–1Mo (also referred to as Grade 91), and to a potential alternate, normalized and tempered 214 Cr–1Mo, is illustrated, and the relative advantages and disadvantages of the materials are discussed.
Vapor Phase Deposition Using a Plasma Spray Process
Authors: von Niessen Konstantin , Gindrat Malko
Published: February 2011

Plasma spray-physical vapor deposition (PS-PVD) is a low pressure plasma spray technology recently developed by Sulzer Metco AG (Switzerland) to deposit coatings out of the vapor phase. PS-PVD is developed on the basis of the well established low pressure plasma spraying technology. In comparison to conventional vacuum plasma spraying and low pressure plasma spraying, these new processes use a high energy plasma gun operated at a work pressure below 2 mbar. This leads to unconventional plasma jet characteristics, which can be used to obtain specific and unique coatings. An important new feature of PS-PVD is the possibility to deposit a coating not only by melting the feed stock material, which builds up a layer from liquid splats, but also by vaporizing the injected material. Therefore, the PS-PVD process fills the gap between the conventional PVD technologies and standard thermal spray processes. The possibility to vaporize feedstock material and to produce layers out of the vapor phase results in new and unique coating microstructures. The properties of such coatings are superior to those of thermal spray and electron beam-physical vapor deposition (EB-PVD) coatings. In contrast to EB-PVD, PS-PVD incorporates the vaporized coating material into a supersonic plasma plume. Due to the forced gas stream of the plasma jet, complex shaped parts like multi-airfoil turbine vanes can be coated with columnar thermal barrier coatings using PS-PVD. Even shadowed areas and areas, which are not in the line-of-sight to the coating source, can be coated homogeneously. This paper reports on the progress made by Sulzer Metco to develop a thermal spray process to produce coatings out of the vapor phase. Columnar thermal barrier coatings made of yttria stabilized zircona are optimized to serve in a turbine engine. This includes coating properties like strain tolerance and erosion resistance but also the coverage of multiple air foils.
Stirling Engines for Distributed Low-Cost Solar-Thermal-Electric Power Generation
Authors: Der Minassians Artin , Sanders Seth R.
Published: February 2011

Due to their high relative cost, solar-electric energy systems have yet to be exploited on a widespread basis. It is believed in the energy community that a technology similar to photovoltaics, but offered at about $1/W, would lead to widespread deployment at residential and commercial sites. This paper addresses the feasibility study of a low-cost solar-thermal electricity generation technology, suitable for distributed deployment. Specifically, we discuss a system based on nonimaging solar concentrators, integrated with free-piston Stirling engine devices incorporating integrated electric generation. We target concentrator collector operation at moderate temperatures, in the range of 120°C to 150°C. This temperature range is consistent with the use of optical concentrators with low-concentration ratios, wide angles of radiation acceptance which are compatible with no diurnal tracking and no or only a few seasonal adjustments. Therefore, costs and reliability hazards associated with tracking hardware systems are avoided. This paper further outlines the design, fabrication, and test results of a single-phase free-piston Stirling engine prototype. A very low loss resonant displacer piston is designed for the system using a very linear magnetic spring. The power piston, which is not mechanically linked to the displacer piston, forms a mass-spring resonating subsystem with the gas spring, and has a resonant frequency matched to that of the displacer. The design of heat exchangers is discussed, with an emphasis on their low fluid friction losses. Only standard low-cost materials and manufacturing methods are required to realize such a machine. The fabricated engine prototype is successfully tested as an engine, and the experimental results are presented and discussed. Extensive experimentation on individual component subsystems confirms the theoretical models and design considerations. Based on the experimental results and the verified component models, an appropriately dimensioned Stirling engine candidate is discussed.
A Finite Element Analysis of Single-Walled Carbon Nanotube Deformation
Authors: Fang Chao , Kumar Ajeet , Mukherjee Subrata
Published: February 2011

Chandraseker et al. (2009, “An Atomistic-Continuum Cosserat Rod Model of Carbon Nanotubes,” J. Mech. Phys. Solids, 57, pp. 932–958), in a 2009 JMPS paper, proposed an atomistic-continuum model, based on Cosserat rod theory, for deformation of a single-walled carbon nanotube (SWNT). This model allows extension and twist, as well as shear and bending (in two directions) of a SWNT. This present paper proposes a finite element method (FEM) implementation of the above mentioned Cosserat rod model for a SWNT, subjected, in general, to axial and transverse loads, as well as bending moments and torques. The resulting FEM implementation includes both geometric and material nonlinearities. Numerical results for several examples are presented in this paper. Finally, a recent experimental paper on SWNTs (Xu, Y-.Q., et al., 2009, “Bending and Twisting of Suspended Single-Walled Carbon Nanotubes in Solution,” ASAP Nano Lett., 9, pp. 1609–1614) is revisited herein. It is pointed out in the present paper that Xu et al. attempted to determine the bending stiffness of a SWNT from an experiment in which the dominant mode of deformation is stretching, not bending. (Their model, Euler–Bernoulli beam bending, should perhaps have been extended to include stretching.) As a result, their measured deflection is nearly insensitive to the bending modulus.
SiN membranes with submicrometer hole arrays patterned by wafer-scale nanosphere lithography
Authors: Klein Mona J. K. , Montagne Franck , Blondiaux Nicolas , Vazquez-Mena Oscar , Heinzelmann Harry , Pugin Raphael , Brugger Juergen , Savu Veronica
Published: February 2011

In this work, nanosphere lithography was integrated with standard microfabrication for the wafer-scale fabrication of silicon nitride (SiN) membranes with arrays of submicrometer holes. A monolayer of polystyrene (PS) beads with a mean diameter of 428 or 535 nm was spin coated onto the front side of a (100)-silicon wafer double-side coated with 100 nm of low-stress SiN. The size of the deposited PS beads was reduced by oxygen plasma reactive ion etching. This allowed to tune the hole size in the released SiN membrane while maintaining the hole array periodicity. Using the size-reduced PS beads as a lift-off template in a standard nanosphere lithography lift-off procedure, a 20 nm thick chromium hole etch mask was realized. This hole mask was patterned by UV photolithography, thus allowing for the local dry-etching of holes into the SiN layer. The holey areas were released from the backside in a combined Si dry- and wet-etch process. During the final wet etch, the wafer front side was protected with a KOH-resistant polymeric coating (ProTEK®). In this way, holey SiN membranes with side lengths ranging from 400 μm up to 2.4 mm were fabricated. Preliminary application specific experiments show the membranes’ suitability for microfiltration and stencil applications.