bluuebunny/crossref_metadata_2025 huggingface dataset:
Time‐Dependent Changes in B‐Type Natriuretic Peptide After Heart Transplantation: Correlation With Allograft Rejection and Function
Authors: Bader Feras M. , Rogers R. Kevin , Kfoury Abdallah G. , Gilbert Edward M. , Horne Ben D. , Stehlik Josef , Renlund Dale G.
Published: April 2009

Endomyocardial biopsy is the gold standard to diagnose cardiac allograft rejection, although a noninvasive modality such as brain natriuretic peptide (BNP) is attractive. The authors examined the correlation of BNP levels with rejection patterns and allograft function in cardiac allograft recipients followed up to 8 years. One hundred forty‐four consecutive patients underwent endomyocardial biopsy, right heart catheterization, and blood sampling. BNP levels decreased during the first 6 months after transplant but then reached a plateau. Time‐dependent correlations were made between BNP levels and allograft rejection, left ventricular ejection fraction, pulmonary capillary wedge pressure, right atrial pressure, and serum creatinine. BNP levels were not different between patients with any rejection pattern and no rejection prior to or after 6 months following transplant. BNP levels did not correlate with ejection fraction, pulmonary capillary wedge pressure, right atrial pressure, or creatinine in the first 6 months after transplant. Statistically significant correlations existed between BNP and these parameters after 6 months following transplant. In cardiac transplant recipients, BNP levels decrease in the first 6 months following transplant and then reach a plateau regardless of the presence, type, or severity of allograft rejection. BNP levels do predict allograft rejection but correlate with allograft function after 6 months following transplant.
Effect of Aldosterone Antagonism on Exercise Tolerance, Doppler Diastolic Function, and Quality of Life in Older Women With Diastolic Heart Failure
Authors: Daniel Kurt R. , Wells Gretchen , Stewart Kathryn , Moore Brian , Kitzman Dalane W.
Published: April 2009

Optimal therapy for diastolic heart failure (DHF), the most common form of heart failure in older persons, is unclear. To determine the effect of aldosterone antagonism in DHF, the authors conducted an open‐label preliminary trial of spironolactone 25 mg/d in 11 women with DHF. Cardiopulmonary exercise testing, Doppler echocardiography, and a quality‐of‐life survey were administered at baseline and after 4 months. Peak exercise VO2 increased by 8.3% (P=.001), the ratio of Doppler diastolic early filling velocity to mitral annulus velocity decreased by 25% (P=.02), quality‐of‐life score improved by 21% (P=.16 for trend), and median New York Heart Association class improved from class III to class II (P=.004). Findings from this preliminary study confirm the role of aldosterone in the pathophysiology of DHF and suggest that aldosterone antagonism may benefit such patients. These hypotheses are currently being tested in two separated National Institutes of Health–funded, randomized trials, the Spironolactone for Failure in the Elderly (SPIFFIE) and the Treatment of Preserved Cardiac Function Heart Failure With an Aldosterone Antagonist (TOPCAT) trials.
Optimal Left Ventricular Lead Position Predicts Reverse Remodeling and Survival After Cardiac Resynchronization Therapy
Authors: Tepper David , Harris Scott , Ip Randy
Published: April 2009

Abstract.  Objectives.  The aim of the current study was to evaluate echocardiographic parameters after 6 months of cardiac resynchronization therapy (CRT) as well as long‐term outcome in patients with the left ventricular (LV) lead positioned at the site of latest activation (concordant LV lead position) as compared with that seen in patients with a discordant LV lead position.

Background.  A nonoptimal LV pacing lead position may be a potential cause for nonresponse to CRT.

Methods.  The site of latest mechanical activation was determined by speckle tracking radial strain analysis and related to the LV lead position on chest x‐ray in 244 CRT candidates. Echocardiographic evaluation was performed after 6 months. Long‐term follow‐up included all‐cause mortality and hospitalizations for heart failure.

Results.  Significant LV reverse remodeling (reduction in LV end‐systolic volume from 189±83 mL to 134±71 mL, P<.001) was noted in the group of patients with a concordant LV lead position (n=153, 63%), whereas patients with a discordant lead position showed no significant improvements. In addition, during long‐term follow‐up (32±16 months), less events (combined for heart failure hospitalizations and death) were reported in patients with a concordant LV lead position. Moreover, a concordant LV lead position appeared to be an independent predictor of hospitalization‐free survival after long‐term CRT (hazard ratio: 0.22, P=.004).

Conclusions.  Pacing at the site of latest mechanical activation, as determined by speckle tracking radial strain analysis, resulted in superior echocardiographic response after 6 months of CRT and better prognosis during long‐term follow‐up.
Racial and Gender Trends in the Use of Implantable Cardioverter‐Defibrillators Among Medicare Beneficiaries Between 1997 and 2003
Authors: Chan Paul S. , Birkmeyer John D. , Krumholz Harlan M. , Spertus John A. , Nallamothu Brahmajee K.
Published: April 2009

Differences in the use of implantable cardioverter‐defibrillators (ICDs) have been reported, but the extent to which they have widened after the publication of major clinical trials supporting their use is unclear. Using data on Medicare beneficiaries, the authors determined annual age‐standardized population‐based utilization rates of ICDs for white men, black men, white women, and black women from 1997 to 2003. During the study period, overall use of ICDs increased most for white men (81.7–254.7 procedures per 100,000 from 1997 to 2003) and black men (38.0–151.7 procedures per 100,000), with white women (28.9–98.4 procedures per 100,000) and black women (18.2–77.3 procedures per 100,000) showing smaller increases in comparison. After adjustment with multivariable regression models, differences in utilization rates between whites and men widened compared with blacks and women between 1997 and 2003, a period when indications for ICD therapy have expanded.
Avian influenza at both ends of a migratory flyway: characterizing viral genomic diversity to optimize surveillance plans for North America
Authors: Pearce John M. , Ramey Andrew M. , Flint Paul L. , Koehler Anson V. , Fleskes Joseph P. , Franson J. Christian , Hall Jeffrey S. , Derksen Dirk V. , Ip Hon S.
Published: April 2009

Although continental populations of avian influenza viruses are genetically distinct, transcontinental reassortment in low pathogenic avian influenza (LPAI) viruses has been detected in migratory birds. Thus, genomic analyses of LPAI viruses could serve as an approach to prioritize species and regions targeted by North American surveillance activities for foreign origin highly pathogenic avian influenza (HPAI). To assess the applicability of this approach, we conducted a phylogenetic and population genetic analysis of 68 viral genomes isolated from the northern pintail (Anas acuta) at opposite ends of the Pacific migratory flyway in North America. We found limited evidence for Asian LPAI lineages on wintering areas used by northern pintails in California in contrast to a higher frequency on breeding locales of Alaska. Our results indicate that the number of Asian LPAI lineages observed in Alaskan northern pintails, and the nucleotide composition of LPAI lineages, is not maintained through fall migration. Accordingly, our data indicate that surveillance of Pacific Flyway northern pintails to detect foreign avian influenza viruses would be most effective in Alaska. North American surveillance plans could be optimized through an analysis of LPAI genomics from species that demonstrate evolutionary linkages with European or Asian lineages and in regions that have overlapping migratory flyways with areas of HPAI outbreaks.
Neurotrophins in chronic cough: association with asthma but not with cough severity
Authors: Koskela Heikki Olavi , Purokivi Minna Katariina , Romppanen Jarkko
Published: April 2009

Background and Aims:  Chronic cough is associated with an enhanced excitability of airway cough receptors, possibly due to action of neurotrophins. The present study aimed to compare the neurotrophin levels between healthy subjects and patients with chronic cough and to analyze the factors associated with these levels.

Methods:  Serum and sputum levels of nerve growth factor (NGF), serum levels of brain‐derived neurotrophic factor (BDNF), and neurotrophin‐3 (NT‐3) were analyzed by enzyme immunoassay in 19 healthy subjects and 47 patients with chronic cough. In addition, cough sensitivity to hypertonic saline was assessed, cough diary was kept, Leicester Cough Questionnaire was filled in, peak flow was monitored and spirometry, skin prick tests, exhaled nitric oxide measurement and histamine challenge were performed.

Results:  The NGF levels did not differ between the healthy subjects and the patients with chronic cough and were not associated with any index describing cough severity. However, these levels in both serum (P = 0.01) and sputum (P = 0.025) samples were associated with asthma. There was a statistically significant association between serum and sputum NGF levels (R = 0.45, P = 0.026). The serum BDNF levels did not differ between the groups and were not associated with any of the background characteristics. The serum NT‐3 levels were below the detection limit in most subjects and therefore these data were not analyzed.

Conclusions:  Neither chronic cough nor its severity is associated with abnormal neurotrophin levels. High NGF levels among some patients with chronic cough may indicate a presence of asthma.

Please cite this paper as: Koskela HO, Purokivi MK and Romppanen J. Neurotrophins in chronic cough: association with asthma but not with cough severity. The Clinical Respiratory Journal 2009; DOI:10.1111/j.1752‐699X.2009.00143.x.
Inhibition of Protein 4.1 R and NuMA Interaction by Mutagenization of Their Binding‐Sites Abrogates Nuclear Localization of 4.1 R
Authors: Mattagajasingh Subhendra N. , Huang Shu‐Ching , Benz Edward J.
Published: April 2009

Protein 4.1R(4.1R) is a multifunctional structural protein recently implicated in nuclear assembly and cell division. We earlier demonstrated that 4.1R forms a multiprotein complex with mitotic spindle and spindle pole organizing proteins, such as NuMA, dynein, and dynactin, by binding to residues 1788–1810 of NuMA through amino acids encoded by exons 20 and 21 in 24 kD domain. Employing random‐and site‐directed mutagenesis combined with glycine‐ and alanine‐scanning, we have identified amino acids of 4.1 R and NuMA that sustain their interaction, and have analyzed the effect of mutating the binding sites on their intracellular colocalization. We found that V762, V765, and V767 of 4.1 R, and 11800, 11801,11803, Tl 804, and M1805 of NuMA are necessary for their interaction. GST‐fusion peptides of the 4.1R24 kD domain bound to residues 1785–2115 of NuMA in in vitro binding assays, but the binding was inhibited by alanine substitutions of V762, V765, and V767 of 4.1 R, or residues 1800–1805 of NuMA. Additionally, expression of variants of 4.1 R or NuMA that inhibit their in vitro binding also abrogated nuclear localization of 4.1 Rand colocalization with NuMA. Our findings suggest a crucial role of 4.1 R/NuMA interaction in localization and function of 4.1 R in the nucleus.
An Operational Perspective of Challenging Statistical Dogma While Establishing a Modern, Secure Distributed Data Management and Imaging Transport System: The Pediatric Brain Tumor Consortium Phase I Experience
Authors: Onar Arzu , Ramamurthy Uma , Wallace Dana , Boyett James M.
Published: April 2009

The Pediatric Brain Tumor Consortium (PBTC) is a multidisciplinary cooperative research organization devoted to the study of correlative tumor biology and new therapies for primary central nervous system (CNS) tumors of childhood. The PBTC was created in 1999 to conduct early‐phase studies in a rapid fashion in order to provide sound scientific foundation for the Children's Oncology Group to conduct definitive trials. The Operations and Biostatistics Center (OBC) of the PBTC is responsible for centrally administering study design and trial development, study conduct and monitoring, data collection and management as well as various regulatory and compliance processes. The phase I designs utilized for the consortium trials have accommodated challenges unique to pediatric trials such as body surface area (BSA)‐based dosing in the absence of pediatric formulations of oral agents. Further during the past decade, the OBC has developed and implemented a state‐of‐the‐art secure and efficient internet‐based paperless distributed data management system. Additional web‐based systems are also in place for tracking and distributing correlative study data as well as neuroimaging files. These systems enable effective communications among the members of the consortium and facilitate the conduct and timely reporting of multi‐institutional early‐phase clinical trials.
Marcus Gunn (jaw‐winking) phenomenon: a case report
Authors: McNamara Clare , Hartnett C. , McNamara CM.
Published: April 2009

While Marcus Gunn phenomenon (MGP) is well documented in the medical literature, little data exist within the dental literature. This is a case report of an adolescent with MGP who presented for orthodontic treatment and required bite‐opening in order to treat her malocclusion. No operative complications were experienced and orthodontic treatment has been uneventful. Although MGP may be uncommon in a dental context, dentists and other oral health professionals can play a significant part in its detection and diagnosis.
Dental health of patients with Parkinson's disease in Iceland
Authors: Einarsdóttir Erna Rún , Gunnsteinsdóttir Hallfrídur , Hallsdóttir Margrét Huld , Sveinsson Sigurjón , Jónsdóttir Sonja Rut , Olafsson Vilhelm Grétar , Bragason Thorvaldur Halldór , Sæmundsson Sigurdur Rúnar , Holbrook William Peter
Published: April 2009

The oral and dental health of patients with Parkinson's disease (PD) has not been well documented and the findings are conflicting. Patients with PD were invited to take part in a clinical and radiographic examination together with a comparison control group of persons who were a spouse or family member. Subjects (n = 67) and controls (n = 55) were examined and compared. Subjects with PD had more missing teeth, caries, dental plaque, and poorer periodontal health. Counts of cariogenic bacteria in saliva were significantly higher for subjects with PD. They did not consume more sweets or sugar, did not brush less frequently, used dental floss more than controls, and visited the dentist at least as often. Salivary flow levels were comparable between subjects with PD and controls. The lack of muscular control may explain the poorer oral health of patients with PD. Dentists and patients with PD may be reluctant to embark on complex dental procedures, and this may explain the increased number of missing teeth in persons with PD in this study.
Laser as a therapy for dry mouth symptoms in a patient with Sjögren's syndrome: a case report
Authors: Simões Alyne , Platero Maira Duque , Campos Luana , Aranha Ana Cecília , Eduardo Carlos de Paula , Nicolau José
Published: April 2009

This clinical case study reports on dry mouth symptoms in a patient with Sjögren's syndrome (SS) who was treated with laser phototherapy (LPT). A 60‐year‐old woman diagnosed with SS was referred to the laboratory for lasers in dentistry to treat her severe xerostomia. A diode laser (780 nm, 3.8 J/cm2, 15 mW) was used to irradiate the parotid, submandibular, and sublingual glands, three times per week, for a period of 8 months. The salivary flow rate and xerostomia symptoms were measured before, during, and after LPT. Dry mouth symptoms improved during LPT. After LPT, the parotid salivary gland pain and swelling were no longer present. Treatment with LPT was an effective method to improve the quality of life of this patient with SS.
Periodontal management of a patient with severe aplastic anemia: a case report
Authors: Agnihotri Rupali , Bhat Khandige Mahalinga , Bhat Giliyar Subraya , Pandurang Pratibha
Published: April 2009

This article describes the periodontal management of a patient with severe aplastic anemia. A 51‐year‐old female patient was hospitalized with aplastic anemia and was referred for the management of her cyclosporine‐induced gingival enlargement and bleeding from her gums. She also complained of pain in the palatal area and the mandibular anterior region. The patient was managed successfully with supra‐ and subgingival instrumentation, local drug delivery (LDD), electrosurgery, repeated oral hygiene instruction, and constant supervision. The treatment resulted in dramatic improvement in the patient's oral health and quality of life. This report highlights the importance of nonsurgical therapy followed by electrosurgery for the management of residual gingival enlargement.
Inventory Management for Customers with Alternative Lead Times
Authors: Wang Haifeng , Yan Houmin
Published: April 2009

It is common for suppliers operating in batch‐production mode to deal with patient and impatient customers. This paper considers inventory models in which a supplier provides alternative lead times to its customers: a short or a long lead time. Orders from patient customers can be taken by the supplier and included in the next production cycle, while orders from impatient customers have to be satisfied from the on‐hand inventory. We denote the action to commit one unit of on‐hand inventory to patient or impatient customers as the inventory‐commitment decision, and the initial inventory stocking as the inventory‐replenishment decision. We first characterize the optimal inventory‐commitment policy as a threshold type, and then prove that the optimal inventory‐replenishment policy is a base‐stock type. Then, we extend our analysis to models to consider cases of a multi‐cycle setting, a supply‐capacity constraint, and the on‐line charged inventory‐holding cost. We also evaluate and compare the performances of the optimal inventory‐commitment policy and the inventory‐rationing policy. Finally, to further investigate the benefits and pitfalls of introducing an alternative lead‐time choice, we use the customer‐choice model to study the demand gains and losses, known as demand‐induction and demand‐cannibalization effects, respectively.
Geometric Optimization of Spatial Compliant Mechanisms Using Three-Dimensional Wide Curves
Authors: Zhou Hong , Ting Kwun-Lon
Published: April 2009

A three-dimensional wide curve is a spatial curve with variable cross sections. This paper introduces a geometric optimization method for spatial compliant mechanisms by using three-dimensional wide curves. In this paper, every material connection in a spatial compliant mechanism is represented by a three-dimensional wide curve and the whole spatial compliant mechanism is modeled as a set of connected three-dimensional wide curves. The geometric optimization of a spatial compliant mechanism is considered as the generation and optimal selection of the control parameters of the corresponding three-dimensional parametric wide curves. The deformation and performance of spatial compliant mechanisms are evaluated by the isoparametric degenerate-continuum nonlinear finite element procedure. The problem-dependent objectives are optimized and the practical constraints are imposed during the optimization process. The optimization problem is solved by the MATLAB constrained nonlinear programming algorithm.
Design of Perfectly Statically Balanced One-DOF Planar Linkages With Revolute Joints Only
Authors: Lin Po-Yang , Shieh Win-Bin , Chen Dar-Zen
Published: April 2009

A systematic methodology for the design of a statically balanced, single degree-of-freedom planar linkage is presented. This design methodology is based on the concept of conservation of potential energy, formulated by the use of complex number notations as link vectors of the linkage. By incorporating the loop closure equations and the kinematic constraints, the gravitational potential energy of the system can be formulated as the function of the vectors of all ground-adjacent links. The balance of the gravitational potential energy of the system is then accomplished by the elastic potential energy of a zero free-length spring on each ground-adjacent link of the linkage. As a result, spring constants and installation configurations of the ground-attached springs are obtained. Since the variation in the gravitational potential energy of the linkage at all configurations can be fully compensated by that of the elastic potential energy of the ground-attached springs, this methodology provides an exact solution for the design of a general spring balancing mechanism without auxiliary parallel links. Illustrations of the methodology are successfully demonstrated by the spring balancing designs of a general Stephenson-III type six-bar linkage and a Watt-I type six-bar linkage with parallel motion.
Novel Third-Order Correction for a Helical Gear Shaping Cutter Made by a Lengthwise-Reciprocating Grinding Process
Authors: Huang Chin-Lung , Fong Zhang-Hua , Chen Shi-Duang , Chang Kuang-Rong
Published: April 2009

Although the Isoform® lengthwise-reciprocating grinding process is considered as one of the most accurate methods for generating the tooth profile geometry of a helical gear shaping cutter, the tooth profile accuracy produced by the Isoform® with a straight cone grinding wheel is not accurate enough for high precision requirement. That is why the shaper cutter is used as a rough cutting tool for most cases. A third-order profile correction to the cone grinding wheel is proposed to increase the accuracy of the work gear profile. A novel topography is developed to schematically show the work gear tooth profile accuracy cut by a resharpened shaping cutter. The profile errors corresponding to the varied resharpening depth are shown in the topography with information of true involute form diameter and semitopping depth. The usable resharpening depth of the shaping cutter can be determined by this topography. The numerical result indicates that third-order correction reduces the profile error of the major cutter enveloping gear to submicro and extends the resharpening depth.
A Reactive Fe-YSZ Coated Foam Device for Solar Two-Step Water Splitting
Authors: Kodama Tatsuya , Hasegawa Tomoki , Nagasaki Ayumi , Gokon Nobuyuki
Published: April 2009

A thermochemical two-step water-splitting cycle using a redox system of iron-based oxides or ferrites is one of the promising processes for converting solar energy into clean hydrogen in sunbelt regions. An iron-containing yttrium-stabilized zirconia (YSZ) or Fe-YSZ is a promising working redox material for the two-step water-splitting cycle. Fe2+-YSZ is formed by a high-temperature reaction between YSZ and Fe3O4 supported on the YSZ at 1400°C in an inert atmosphere. Fe2+-YSZ reacts with steam and generates hydrogen at 1000–1100°C to form Fe3+-YSZ that is reactivated by thermal reduction in a separate step at temperatures above 1400°C under an inert atmosphere. In the present study, ceramic foam coated with Fe-YSZ particles is examined as the thermochemical water-splitting device to be used in a solar directly irradiated receiver/reactor system. The Fe-YSZ particles were coated on an Mg-partially stabilized zirconia foam disk, and the foam device was tested during the two-step water-splitting cycle; this was performed alternately at temperatures between 1100°C and 1400°C. The foam device was irradiated by concentrated visible light from a sun simulator at a peak flux density of 925 kW/m2 and an average flux density of 415 kW/m2 (total power input on the surface of the foam was 0.296 kW) in a N2 gas stream; subsequently, it was reacted with steam at 1100°C while heating by an infrared furnace. Hydrogen successfully continued to be produced in the repeated cycles.
Stable Cu-Based Back Contacts for CdTe Thin Film Photovoltaic Devices
Authors: Enzenroth R. A. , Barth K. L. , Sampath W. S. , Manivannan V. , Kirkpatrick A. T. , Noronha P.
Published: April 2009

Cadmium telluride (CdTe) thin film photovoltaic devices fabricated in a-line process developed at Colorado State University (CSU) have shown stability during long-term (over a 5 year period) accelerated stress testing. These devices have a copper (Cu) containing back contact. The Cu profile as measured by secondary ion mass spectrometry characterization shows, for the maximum stressed device (23,399 h), that there is a significant (two times) change in the concentration of secondary Cu ions in the bulk of the material; however, the Cu concentration gradient at the back of the device has no significant change, and the CdS layer has no significant Cu concentration increase at open-circuit bias and 65°C temperature conditions. This indicates that with a proper CdCl2 treatment, Cu can be used to form the back contact for CdTe devices with acceptable stability. These devices have a projected field lifetime of greater than 60 years.
Comparison of Predicted to Measured Photovoltaic Module Performance
Authors: Fanney A. Hunter , Dougherty Brian P. , Davis Mark W.
Published: April 2009

To accurately predict the electrical performance of photovoltaic modules computer simulation models are essential. Without such models, potential purchasers of photovoltaic systems have insufficient information to judge the relative merits and cost effectiveness of photovoltaic systems. The purpose of this paper is to compare the predictions of a simulation model, developed by Sandia National Laboratories, to measurements from photovoltaic modules installed in a vertical wall façade in Gaithersburg, MD. The photovoltaic modules were fabricated using monocrystalline, polycrystalline, tandem-junction amorphous, and copper-indium diselenide cells. Polycrystalline modules were constructed using three different glazing materials: 6 mm low-iron glass, 0.05 mm ethylene-tetrafluoroethylene copolymer, and 0.05 mm polyvinylidene fluoride. In order to only assess the simulation model’s ability to predict photovoltaic module performance, measured solar radiation data in the plane of the modules is initially used. Additional comparisons are made using horizontal radiation measurements. The ability of the model to accurately predict the temperature of the photovoltaic cells is investigated by comparing predicted energy production using measured versus predicted photovoltaic cell temperatures. The model was able to predict the measured annual energy production of the photovoltaic modules, with the exception of the tandem-junction amorphous modules, to within 6% using vertical irradiance measurements. The model overpredicted the annual energy production by approximately 14% for the tandem-junction amorphous panels. Using measured horizontal irradiance as input to the simulation model, the agreement between measured and predicted annual energy predictions varied between 1% and 8%, again with the exception of the tandem-junction amorphous silicon modules. The large difference between measured and predicted results for the tandem-junction modules is attributed to performance degradation. Power measurements of the tandem-junction amorphous modules at standard reporting conditions prior to and after exposure revealed a 12% decline. Supplying post exposure module parameters to the model resulted in energy predictions within 5% of measured values.
A Novel Design for a Cheap High Temperature Solar Collector: The Rotating Solar Boiler
Authors: van Luijtelaer Jeroen P. H. , Kroon Maaike C.
Published: April 2009

In this work a novel type of high temperature solar collector is designed: the rotating solar boiler. This rotating solar boiler consists of two concentric tubes. The inner tube, called absorber, absorbs sunlight and boils water. The outer transparent tube, called cover, is filled with air. The boiler rotates to completely prevent convection in the insulating air layer in between the tubes. In this way, the heat loss is reduced considerably resulting in a solar collector that is more efficient than conventional flat plate solar collectors. The prototype built measured 1.20 m length and 0.50 m diameter (illuminated area is 0.60 m2) for the copper absorber with high performance sputtered coating. The cover with a diameter of 0.90 m was made of transparent polyvinylchloride film. The rotation speed was 60 rpm. The efficiency was 61% and the boiler delivered 0.34 kW of 100°C steam at an ambient temperature of 7°C. A model was developed to predict the performance of the prototype. The model predicts an efficiency of 62%, which is in agreement with the measured experimental efficiency. An economical analysis was performed as well. The rotating solar boiler is much cheaper than conventional evacuated tube collectors, especially because the rotating solar boiler is lightweight.
Infrared-Reflective Coating on Fused Silica for a Solar High-Temperature Receiver
Authors: Röger Marc , Rickers Christoph , Uhlig Ralf , Neumann Frank , Polenzky Christina
Published: April 2009

In concentrating solar power, high-temperature solar receivers can provide heat to highly efficient cycles for electricity or chemical production. Excessive heating of the fused-silica window and the resulting recrystallization are major problems of high-temperature receivers using windows. Excessive window temperatures can be avoided by applying an infrared-reflective solar-transparent coating on the fused-silica window inside. Both glass temperatures and receiver losses can be reduced. An ideal coating reflects part of the thermal spectrum (λ>2.5 μm) of the hot absorber (1100°C) back onto it without reducing solar transmittance. Extensive radiation simulations were done to screen different filter types. The examined transparent conductive oxides involve a high solar absorptance, inhibiting their use in high-concentration solar systems. Although conventional dielectric interference filters have a low solar absorption, the reflection of solar radiation, which comes from various directions, is too high. It was found that only rugate filters fulfill the requirements for operation under high-flux solar radiation with different incident angles. A thermodynamic qualification simulation of the rugate coating on a window of a flat-plate receiver showed a reduction of almost 175 K in mean window temperature and 11% in receiver losses compared with an uncoated window. For the configuration of a pressurized receiver (REFOS type), the temperature could be reduced by 65 K with slightly reduced receiver losses. Finally, a 25 μm thick rugate filter was manufactured and optically characterized. The measured spectra fitted approximately the design spectra, except for two absorption peaks, which can be avoided in future depositions by changing the deposition geometry and by using in situ monitoring. The issue of this paper is to share the work done on the choice of filter type, filter design, thermodynamic evaluation, and deposition experiments.
Design and Construction of an Air Cooled Ammonia Absorber
Authors: Velázquez Nicolás , Sauceda Daniel , Quintero-Núñez Margarito , Best Roberto
Published: April 2009

This paper presents the design criteria, methodology. and results of the basic and detailed engineering for a descending film ammonia absorber using air cooled finned tubes, which is part of an advanced absorption cooling system (solar generator absorber heat exchange cycle). The design consists in determining all the construction parameters for the air cooled ammonia absorption unit, starting with the operating conditions defined by a thermodynamical simulation of the process considering both physical and operational design restrictions. The chosen option was based on a comparison between the advantages and disadvantages of each possible array, type, and geometry. After performing the operational simulation, thermal and mechanical designs, and the consistency analysis, it was found that an absorption unit using 29 5/8 NPT 14 (BWG) steel carbon ASTM A-179 tubes, with pure SB-234 aluminum fins was the best option. The tubes are arranged in an equilateral triangle fashion, with crossed air flow cooling.
Multiphase Stirling Engines
Authors: Der Minassians Artin , Sanders Seth R.
Published: April 2009

Analysis, design, fabrication, and experimental assessment of a symmetric three-phase free-piston Stirling engine system is discussed in this paper. The system is designed to operate with moderate-temperature heat input that is consistent with solar-thermal collectors. Diaphragm pistons and nylon flexures are considered for this prototype to eliminate surface friction and to provide appropriate seals. In addition, low loss diaphragm pistons, etched and woven-wire screen heat exchangers, and plastic flexures, as the main components of the system, are outlined. The experimental results are presented and compared with design analysis. Experiments successfully confirm the design models for heat exchanger flow friction losses and gas spring hysteresis dissipation. Furthermore, it is revealed that gas spring hysteresis loss is an important dissipation phenomenon for low-power Stirling engines and should be carefully addressed in design. Analysis shows that the gas hysteresis dissipation is reduced drastically by increasing the number of phases in a multiphase Stirling engine system. It is further shown that for an even number of phases, half of the engine chambers could be eliminated by utilizing a reversing mechanism within the multiphase system. The mathematical formulation and modal analysis of multiphase Stirling engine system are then extended to a system that incorporates a reverser. By introducing a reverser to the fabricated prototype, the system successfully operates in engine mode. The system proves its self-starting capability and validates the computed start-up temperature.
Analysis Model of Mismatch Power Losses in PV Systems
Authors: Chouder A. , Silvestre S.
Published: April 2009

A novel procedure to extract and analyze the power losses, mainly due to mismatch effects, in a photovoltaic (PV) system is presented. The developed model allows the extraction of the main PV module and PV array parameters from I-V characteristics, as well as in dynamic behavior under real conditions of work. The method allows a good estimation of the mismatch effect on the total PV system power losses.
Comparison of Stratification in a Water Tank and a PCM-Water Tank
Authors: Castell A. , Solé C. , Medrano M. , Nogués M. , Cabeza L. F.
Published: April 2009

Most of the thermal energy storage systems available on the market use water as a storage medium. The improvement of the storage efficiency results in a higher performance of the whole system, and thermal stratification is commonly used for this purpose. On the other hand, in applications with small temperature changes, phase change materials (PCMs) provide high energy density since the latent heat is much larger than the sensible heat. This is the case of stratified hot water tanks, where the temperature change in the top layer is small as it is held close to the usage temperature. The benefits of using PCMs in a water tank, in terms of energy storage density, have been demonstrated before. The time with available hot water is increased because of the energy stored in the PCMs. The aim of this work is to demonstrate that the use of PCMs in the upper part of a water tank holds or improves the benefit of the stratification phenomenon. Two tanks with the same dimensions were compared during charging and discharging processes. One of them is a traditional water tank and the other is a PCM-water tank (a water tank with a phase change material placed at the top).
Modeling of a Multitube High-Temperature Solar Thermochemical Reactor for Hydrogen Production
Authors: Haussener S. , Hirsch D. , Perkins C. , Weimer A. , Lewandowski A. , Steinfeld A.
Published: April 2009

A solar reactor consisting of a cavity-receiver containing an array of tubular absorbers is considered for performing the ZnO-dissociation as part of a two-step H2O-splitting thermochemical cycle using concentrated solar energy. The continuity, momentum, and energy governing equations that couple the rate of heat transfer to the Arrhenius-type reaction kinetics are formulated for an absorbing-emitting-scattering particulate media and numerically solved using a computational fluid dynamics code. Parametric simulations were carried out to examine the influence of the solar flux concentration ratio (3000–6000 suns), number of tubes (1–10), ZnO mass flow rate (2–20 g/min per tube), and ZnO particle size (0.06–1 μm) on the reactor’s performance. The reaction extent reaches completion within 1 s residence time at above 2000 K, yielding a solar-to-chemical energy conversion efficiency of up to 29%.
An Optimum Design of Crowned Cylindrical Roller Bearings Using Genetic Algorithms
Authors: Kumar K. Sunil , Tiwari Rajiv , Prasad P. V. V. N.
Published: April 2009

The long fatigue life is the one of the most important criterion for the design of rolling bearings, however, due to complex and diverse internal geometries, each type of rolling bearings require a different design formulation. To increase the life of cylindrical roller bearings, the profile (or the crowning) of the roller plays an important role. A flat profile of the rolling element results in the edge stress concentrations at roller ends. A circular crowning of roller eliminates the edge stress concentration at the lower and moderate loads only; however, it develops edge stress concentrations at heavy loads. The logarithmic profile of the roller results in no edge stress concentration at the low, medium, and heavy loads; distribution of contact stresses is also nearly uniform along the length of the roller. A design methodology for the optimum design of cylindrical roller bearings with the logarithmic profile has been outlined. A nonlinear constrained optimization problem has been formulated for the design of cylindrical roller bearings with logarithmic profiles and is optimized by using real-coded genetic algorithms. The change in roller profile has not been accounted for explicitly in the standard definition of the dynamic capacity; hence, for the present case directly the Lundberg–Palmgren life equation has been chosen as an objective function. Design variables include four bearing geometrical parameters and the two logarithmic profile generating parameters are considered. In addition to these, another five design constraint constants are also included, which indirectly affect the fatigue life of cylindrical roller bearings. The five design constraint constants have been given bounds based on the parametric studies through initial optimization runs. The effective length of the roller is taken corresponding to the standard roller diameter, which has standard discrete dimensions. Constraint violation study has been performed to have an assessment of the effectiveness of each of the constraints. A convergence study has been carried out to ensure the global optimum point in the design. A sensitivity analysis of various geometric design parameters has been performed using the Monte Carlo simulation technique, in order to see changes in the fatigue life of the bearing. Illustrations show that the multiplier of the logarithmic profile deviation parameter has more effect on the fatigue life as compared with other geometric parameters.
Electrical properties of metal-ferroelectric (PbZr0.53Ti0.47O3)-polysilicon-insulator (Y2O3)-silicon capacitors and field-effect transistors
Authors: Chan Po-Chin , Shih Wen-Chieh , Chang Ingram Yin-Ku , Lee Joseph Ya-min
Published: April 2009

In this work, Al∕PbZr0.53Ti0.47O3(PZT)∕n+-polysilicon/Y2O3∕Si (MFPIS) capacitors and transistors were fabricated. A n+-polysilicon floating gate was used to reduce the depolarization field of the ferroelectric layer. The gate leakage current density was as low as 1.68×10−10A∕cm2 at 5V. The IDS-VGS memory window shows a maximum of 2.5V at a sweeping VGS voltage range of 9V. The subthreshold slope is 169mV∕decade. The IDS-VGS on and off ratio of MFPIS field effect transistor was about 104. The MFPIS field effect transistors maintained a threshold voltage window of about 1.6V after an elapsed time of 104s.
Tunable optical filters with nanostructured suspended gratings
Authors: Ye Jia-Sheng , Kobayashi Takashi , Kanamori Yoshiaki , Hu Fang-Ren , Hane Kazuhiro
Published: April 2009

In this article, the authors report a kind of nanostructured suspended grating (NSG), whose grating beams are connected with narrow mechanical springs at the center. Using an electrostatic comb drive actuator, the period of the fabricated silicon NSG is tuned from 1.20to1.43μm. With the increase in grating period, experimental results reveal that the resonant interference wavelengths are increased, while the resonant interference peaks are decreased. The reflectance interference resonance is associated with a leaky-mode resonance. Theoretical simulations based on a rigorous coupled-wave method are carried out for comparison, from which the resonant interference wavelength shift induced by the tuning grating period can be predicted. It is believed that the NSG should have practical applications in micro-optical systems, such as tunable optical filters.
Contrast reversal effect in scanning electron microscopy due to charging
Authors: Abe H. , Babin S. , Borisov S. , Hamaguchi A. , Kadowaki M. , Miyano Y. , Yamazaki Y.
Published: April 2009

In semiconductor manufacturing, accurate measurement of shapes and sizes of fabricated features is required. These measurements are carried out using critical dimension scanning electron microscope (CD-SEM). Positions of edges are often unclear because of charging. Depending on the SEM setup and the pattern under measurement, the effect of charging varies. The influence of measurement conditions can be simulated and optimized. A Monte Carlo electron beam simulation tool was developed, which takes into account electron scattering and charging. CD-SEM imaging of silicon dioxide lines on silicon was studied. In the experiment, changes in the beam voltage were found to result in contrast tone reversal. The same effect was also found in simulations considering charging. The time dependence of contrast variation was studied. A good agreement between simulation and measurement was found. The simulation software proved reliable in predicting SEM images, which makes it an important instrument to optimize settings of electron beam systems.
DEFORMED HARMONIC OSCILLATOR AND NONLINEAR COHERENT STATES: NONCOMMUTATIVE QUANTUM SPACE APPROACH
Authors: NADERI MOHAMMAD HOSSEIN , SOLTANOLKOTABI MAHMOOD , ROKNIZADEH RASOUL
Published: April 2009

In this paper, by using the Wess–Zumino formalism of noncommutative differential calculus, we show that the concept of nonlinear coherent states originates from noncommutative geometry. For this purpose, we first formulate the differential calculus on a GL p, q(2) quantum plane. By using the commutation relations between coordinates and their interior derivatives, we then construct the two-parameter (p, q)-deformed quantum phase space together with the associated deformed Heisenberg commutation relations. Finally, by applying the obtained results for the quantum harmonic oscillator we construct the associated coherent states, which can be identified as nonlinear coherent states. Furthermore, we show that some of the well-known deformed (nonlinear) coherent states, such as two-parameter (p, q)-deformed coherent states, Maths-type q-deformed coherent states, Phys-type q-deformed coherent states and Quesne deformed coherent states, can be easily obtained from our treatment.
DIQUARK FORMATION IN ANGULAR-MOMENTUM-EXCITED BARYONS
Authors: ANTUNES ANTONIO CARLOS BAPTISTA , ANTUNES LEILA JORGE
Published: April 2009

Diquarks, or metastable clusters of two quarks inside baryons, are shown to be produced by angular momentum excitation. In baryons with a light quark and two heavy quarks with large angular momentum (L>2), the centrifugal barrier that appears in the rotation frame of the two heavy quarks prevents the light quark from passing freely between the two heavy quarks. The light quark must tunnelize through this potential barrier, which gives rise to the clusters of a light and a heavy quark.
INTEGRABLE THEORIES AND LOOP SPACES: FUNDAMENTALS, APPLICATIONS AND NEW DEVELOPMENTS
Authors: ALVAREZ ORLANDO , FERREIRA L. A. , SÁNCHEZ-GUILLÉN J.
Published: April 2009

We review our proposal to generalize the standard two-dimensional flatness construction of Lax–Zakharov–Shabat to relativistic field theories in d+1 dimensions. The fundamentals from the theory of connections on loop spaces are presented and clarified. These ideas are exposed using mathematical tools familiar to physicists. We exhibit recent and new results that relate the locality of the loop space curvature to the diffeomorphism invariance of the loop space holonomy. These result are used to show that the holonomy is Abelian if the holonomy is diffeomorphism invariant.

These results justify in part and set the limitations of the local implementations of the approach which has been worked out in the last decade. We highlight very interesting applications like the construction and the solution of an integrable four-dimensional field theory with Hopf solitons, and new integrability conditions which generalize BPS equations to systems such as Skyrme theories. Applications of these ideas leading to new constructions are implemented in theories that admit volume-preserving diffeomorphisms of the target space as symmetries. Applications to physically relevant systems like Yang–Mills theories are summarized. We also discuss other possibilities that have not yet been explored.
THE INFLUENCE OF SPUTTERING BIAS-VOLTAGE ON LaB6 FILM'S CHARACTERISTICS
Authors: XU JING , MIN GUANGHUI , ZHAO XIAOHUA , HU LIJIE , YU HUASHUN
Published: April 2009

The deposition of lanthanum boride ( LaB 6) thin films by the DC magnetron sputtering were studied. XRD, AFM and Stylus Profiler were used to characterize the properties of the deposited films. The XRD was used to study the crystallinity. The results of the XRD showed that the dominant crystal face is the (100) face. The crystallinity decreased with the increased bias-voltage value, but the influence of bias-voltage on the films is different on different crystal faces. The intensity (100) face was influenced by the bias-voltage more obviously than other faces except the influence of thickness. The diffraction peak maximal intensity of the (100) face changed from 1256 (on 0 V) to 580 (on -150 V), but the intensity of (110) face changed from 614 (on 0 V) to 486 (on -150 V). The rel. int (100%) of the (110) face changed from 38.70 to 74.52. The deposition rate decreased with the increased bias-voltage value, but the decrease was not obvious. The maximum and minimum of the deposition ratio were 17.53 nm and 13.75 nm respectively. Surface morphology of the films was studied by the AFM. The crystallite of the films was less than 50 nm. The maximal roughness of the films decreased first and increased afterward, and the maximum was obtained on the -50 V bias-voltage.
PHASE SPACE MEASURE CONCENTRATION FOR AN IDEAL GAS
Authors: CREACO ANTHONY J. , KALOGEROPOULOS NIKOS
Published: April 2009

We point out that a special case of an ideal gas exhibits concentration of the volume of its phase space, which is a sphere, around its equator in the thermodynamic limit. The rate of approach to the thermodynamic limit is determined. Our argument relies on the spherical isoperimetric inequality of Lévy and Gromov.