bluuebunny/crossref_metadata_2025_split huggingface dataset:
A quantum-well superlattice solar cell for enhanced current output and minimized drop in open-circuit voltage under sunlight concentration
Authors: Sugiyama Masakazu , Wang Yunpeng , Fujii Hiromasa , Sodabanlu Hassanet , Watanabe Kentaroh , Nakano Yoshiaki 
Published: December 2012

Abstract
Insertion of quantum wells (QWs) extends the absorption edge to a longer wavelength than the value of a p-i-n cell without the QWs, which is preferable for the improved current matching of a InGaP/GaAs/Ge multijunction cell. The QWs, however, reduce the open-circuit voltage (V
oc) and degrade the fill factor; the latter is significant for a large number of QWs that are mandatory for sufficient light absorption. As a structure to minimize these drawbacks, a QW superlattice, a strain-balanced In0.13Ga0.86As (4.7 nm)/GaAs0.57P0.43 (3.1 nm) stack, was implemented by metalorganic vapour-phase epitaxy. It brought about an enhancement in short-circuit current density (3.0 mA cm−2) with a minimal drop in V
oc(0.03 V) compared with a p-i-n cell without the superlattice. The collection efficiency of photocarriers from the wells to an external circuit was evaluated: the efficiency was above 0.95 for the superlattice, while it was below 0.8 at a large forward bias for a conventional QW cell with thicker barriers. With the fast electron–hole separation in the superlattice owing to tunnelling transport, the superlattice cell exhibited a steeper increase in V
oc as a function of the sunlight concentration ratio than the conventional QW cell: at the concentration ratio of 50, the value of V
oc for the superlattice cell was almost equivalent to the value of the GaAs p-i-n cell without QWs. As a possible mechanism behind such an enhancement in V
oc, photocurrent generation by two-step photon absorption was observed, using the electron ground state of the superlattice as an intermediate state.
Sputter-grown Si quantum dot nanostructures for tandem solar cells
Authors: Huang Shujuan , Conibeer Gavin 
Published: December 2012

Abstract
Silicon quantum dot (QD)-based ‘all-silicon’ tandem solar cells have emerged as a promising third generation photovoltaic approach to realize high-efficiency and cost effective solar cells. This approach exploits the quantum confinement effect of silicon QDs embedded in a dielectric matrix to engineer the effective electronic bandgap of a solar cell material. Research work in our group has shown that such a Si QD solar cell can be fabricated by co-sputtering of thin layers of Si-rich dielectric sandwiched between stoichiometric dielectric layers which crystallize to form Si QDs of uniform size on annealing. The Si-richness in the Si-rich layer plays an important role in formation of uniform size and shape. The matrix and barrier layer materials also affect the formation of Si QDs. The bandgap tunability of such Si QD superlattice structures has been clearly demonstrated by photoluminescence and electroluminescence measurements. Doping of Si QD layers has been achieved by impurity incorporation of P, Sb or B in the Si-rich layers. Strong evidence of effective doping has been demonstrated from the enhanced conductivity, from the dopant concentrations extracted from MOS structures and from the formation of rectifying p–n junctions which give an open circuit voltage (V
oc) of 492 mV. The doping mechanism is more likely to be modified interface doping rather than direct doping to the Si QDs.
Simulations of ITER in the presence of ITB using the NTV intrinsic toroidal rotation model
Authors: Chatthong B. , Onjun T. 
Published: December 2012

Abstract
Simulations of a standard H-mode International Thermonuclear Experimental Reactor (ITER) scenario in the presence of internal transport barrier (ITB) are carried out using the 1.5D BALDUR integrated predictive modelling code. The intrinsic offset toroidal rotation, which can play an essential role in turbulent transport suppression that results in the ITB formation, is theoretically calculated using a model based on the neoclassical toroidal viscosity (NTV) concept. The core transport in this simulation is a combination of a mixed Bohm/gyro-Bohm anomalous transport model and an NCLASS neoclassical transport model. The boundary condition of the simulations is taken to be at the top of the pedestal where the pedestal value is calculated using the pedestal model based on a combination of pedestal width scaling determined by magnetic/flow shear stabilization and an infinite-n ballooning pressure gradient model. It is found that the predicted intrinsic rotation can result in the formation of ITB, locating mostly between r/a = 0.6 and 0.8 and having a strong impact on the plasma performance in ITER. It is also found that the variations of plasma density and heating power result in a minimal change in toroidal rotation; whereas the increase in plasma effective charge can considerably reduce the toroidal velocity peaking.
Stellarator optimization under several criteria using metaheuristics
Authors: Castejón F , Gómez-Iglesias A , Vega-Rodríguez M A , Jiménez J A , Velasco J L , Romero J A 
Published: December 2012

AbstractA new algorithm based on metaheuristics has been developed to perform stellarator optimization. This algorithm, which is inspired by the behaviour of bees and is called distributed asynchronous bees, has been used for the optimization under three criteria: minimization ofB × grad(B) drift, Mercier and ballooning stability. This algorithm is tested by partially optimizing TJ-II and, afterwards, a three-period optimized configuration is found by performing a full optimization that starts from a three-period heliac.
Microbiota Separation and C‐reactive Protein Elevation in Treatment‐naïve Pediatric Granulomatous Crohn Disease
Authors: Kellermayer Richard , Mir Sabina A.V. , Nagy‐Szakal Dorottya , Cox Stephen B. , Dowd Scot E. , Kaplan Jess L. , Sun Yan , Reddy Sahna , Bronsky Jiri , Winter Harland S. 
Published: December 2012

ABSTRACTObjectives:In patients with inflammatory bowel diseases (IBDs), the presence of noncaseating mucosal granuloma is sufficient for diagnosing Crohn disease (CD) and may represent a specific immune response or microbial‐host interaction. The cause of granulomas in CD is unknown and their association with the intestinal microbiota has not been addressed with high‐throughput methodologies.Methods:The mucosal microbiota from 3 different pediatric centers was studied with 454 pyrosequencing of the bacterial 16S rRNA gene and the fungal small subunit (SSU) ribosomal region in transverse colonic biopsy specimens from 26 controls and 15 treatment‐naïve pediatric CD cases. Mycobacterium avium subspecies paratuberculosis (MAP) was tested with real‐time polymerase chain reaction. The correlation of granulomatous inflammation with C‐reactive protein was expanded to 86 treatment‐naïve CD cases.Results:The CD microbiota separated from controls by distance‐based redundancy analysis (P = 0.035). Mucosal granulomata found in any portion of the intestinal tract associated with an augmented colonic bacterial microbiota divergence (P = 0.013). The granuloma‐based microbiota separation persisted even when research center bias was eliminated (P = 0.04). Decreased Roseburia and Ruminococcus in granulomatous CD were important in this separation; however, principal coordinates analysis did not reveal partitioning of the groups. CRP levels >1 mg/dL predicted the presence of mucosal granulomata (odds ratio 28 [6–134.32]; 73% sensitivity, 91% specificity).Conclusions:Granulomatous CD associates with microbiota separation and C‐reactive protein elevation in treatment‐naïve children; however, overall dysbiosis in pediatric CD appears rather limited. Geographical/center bias should be accounted for in future multicenter microbiota studies.
Upper Gastrointestinal Histopathological Findings in Children and Adolescents With Nonulcer Dyspepsia With Helicobacter pylori Infection
Authors: Carvalho Mary Assis , Machado Nilton Carlos , Ortolan Erika Veruska Paiva , Rodrigues Maria Aparecida Marchesan 
Published: December 2012

ABSTRACTObjectives:The aim of the study was to investigate the histopathological lesions in the upper gastrointestinal mucosa associated with Helicobacter pylori infection in children with nonulcer dyspepsia.Methods:A cross‐sectional case‐control study was performed on 185 Brazilian children and adolescents (4–17 years, mean 9.5 ± 2.7 years), 63.2% girls, submitted to upper gastrointestinal endoscopy. The histopathological lesions of the esophageal and gastric mucosa were analyzed in biopsy samples.Results:H pylori infection was identified in 96 children (51.8%). Moderate to severe chronic active gastritis was present in antrum (70.5%) and corpus (45.2%), with higher grading in antrum than in corpus (P < 0.05). The topographic distribution of inflammation was pangastritis (61.9%), followed by antral (32.1%) and corpus (5.9%). H pylori density was higher in antrum than in corpus. Intestinal metaplasia was not found in the H pylori–infected group, nor was significant gastric atrophy. The scores for esophagitis were significantly higher (P < 0.05) in the noninfected group (1.4 ± 0.8) than in the H pylori–infected group (1.07 ± 0.9), with significant negative correlation (r = 0.29; P < 0.05) with the scores of gastric inflammation.Conclusions:The prevalence of H pylori infection was high among children with dyspepsia and associated with moderate/severe degrees of gastric inflammation. The high scores of esophagitis in the noninfected group point to 2 distinct groups of pathological conditions sharing similar clinical patterns.
Evaluation of the Presence of Hereditary and Acquired Thrombophilias in Brazilian Children and Adolescents With Diagnoses of Portal Vein Thrombosis
Authors: Menezes Ferri Priscila , Rodrigues Ferreira Alexandre , Tavares Fagundes Eleonora Druve , Guerra Xavier Sandra , Dias Ribeiro Daniel , Fernandes Ana Paula , Gomes Borges Karina Braga , Liu Shinfay Maximilian , de Melo Maria do Carmo Barros , Roquete Mariza Leitão Valadares , Penna Francisco José 
Published: December 2012

ABSTRACTObjective:The aim of this study was to describe the prevalence of main hereditary thrombophilias, Janus kinase 2 (JAK2) V617F mutation, antiphospholipid antibody syndrome (APS), and hyperhomocysteinemia in Brazilian children and adolescents diagnosed with portal vein thrombosis (PVT) without associated hepatic disease.Methods:A cross‐sectional study was carried out with 32 children with PVT in accompaniment at Hospital das Clínicas of the Universidade Federal de Minas Gerais from January 1990 to July 2011. Laboratory evaluation of thrombophilias was performed from September 2010 to July 2011.Results:Thirty‐two patients were evaluated; 59% were boys. Median age at diagnosis was 2.4 years. Mean time of patients' accompaniment was between 4.7 and 5.2 years. The presence of hereditary and acquired thrombophilias occurred in 34.4% of patients, and 9 of them also showed other risk factors in the previous history evaluation. Risk factors were absent in the previous history of 18 patients (56.3%). Two patients showed persistent high titres of anticardiolipin antibodies. Hyperhomocysteinemia was not observed. One patient was heterozygous for factor V Leiden and prothrombin G20210A mutation (3.1%). Eleven patients (34.4%) showed heterozygous methylenetetrahydrofolate reductase (MTHFR) C677T, and no patient had the JAK2V617F mutation.Conclusions:Even after investigation of main hereditary and acquired thrombophilia, PVT remains without apparent cause in most patients. Nevertheless, association of local and systemic risk factors seems to be important also in the pediatric age group. Therefore, despite the low prevalence, a complete investigation, which includes both hereditary and acquired thrombophilias, may be necessary.
Predictors of Proctocolectomy in Children With Ulcerative Colitis
Authors: Kelley‐Quon Lorraine I. , Jen Howard C. , Ziring David A. , Gupta Neera , Kirschner Barbara S. , Ferry George D. , Cohen Stanley A. , Winter Harland S. , Heyman Melvin B. , Gold Benjamin D. , Shew Stephen B. 
Published: December 2012

ABSTRACTObjectives:Few clinical predictors are associated with definitive proctocolectomy in children with ulcerative colitis (UC). The purpose of the present study was to identify clinical predictors associated with surgery in children with UC using a disease‐specific database.Methods:Children diagnosed with UC at age <18 years were identified using the Pediatric Inflammatory Bowel Disease Consortium (PediIBDC) database. Demographic and clinical variables from January 1999 to November 2003 were extracted alongside incidence and surgical staging.Results:Review of the PediIBDC database identified 406 children with UC. Approximately half were girls (51%) with an average age at diagnosis of 10.6 ± 4.4 years in both boys and girls. Average follow‐up was 6.8 (±4.0) years. Of the 57 (14%) who underwent surgery, median time to surgery was 3.8 (interquartile range 4.9) years after initial diagnosis. Children presenting with weight loss (hazard ratio [HR] 2.55, 99% confidence interval [CI] 1.21–5.35) or serum albumin <3.5 g/dL (HR 6.05, 99% CI 2.15–17.04) at time of diagnosis and children with a first‐degree relative with UC (HR 1.81, 99% CI 1.25–2.61) required earlier surgical intervention. Furthermore, children treated with cyclosporine (HR 6.11, 99% CI 3.90–9.57) or tacrolimus (HR 3.66, 99% CI 1.60–8.39) also required earlier surgical management. Other symptoms, laboratory tests, and medical therapies were not predictive for need of surgery.Conclusion:Children with UC presenting with hypoalbuminemia, weight loss, a family history of UC, and those treated with calcineurin inhibitors frequently require restorative proctocolectomy for definitive treatment. Early identification and recognition of these factors should be used to shape treatment goals and initiate multidisciplinary care at the time of diagnosis.
Reduction of image noise in low tube current dynamic CT myocardial perfusion imaging using HYPR processing: A time‐attenuation curve analysis
Authors: Speidel Michael A. , Bateman Courtney L. , Tao Yinghua , Raval Amish N. , Hacker Timothy A. , Reeder Scott B. , Van Lysel Michael S. 
Published: December 2012

Purpose:This study describes a HighlY constrained backPRojection (HYPR) image processing method for the reduction of image noise in low tube current time‐resolved CT myocardial perfusion scans. The effect of this method on myocardial time‐attenuation curve noise and fidelity is evaluated in an animal model, using varying levels of tube current.Methods:CT perfusion scans of four healthy pigs (42–59 kg) were acquired at 500, 250, 100, 50, 25, and 10 mA on a 64‐slice scanner (4 cm axial coverage, 120 kV, 0.4 s/rotation, 50 s scan duration). For each scan a sequence of ECG‐gated images centered on 75% R‐R was reconstructed using short‐scan filtered back projection (FBP). HYPR processing was applied to the scans acquired at less than 500 mA using parameters designed to maintain the voxel noise level in the 500‐mA FBP images. The processing method generates a series of composite images by averaging over a sliding time window and then multiplies the composite images by weighting images to restore temporal fidelity to the image sequence. HYPR voxel noise relative to FBP noise was measured in AHA myocardial segment numbers 1, 5, 6, and 7 at each mA. To quantify the agreement between HYPR and FBP time‐attenuation curves (TACs), Bland‐Altman analysis was performed on TACs measured in full myocardial segments. The relative degree of TAC fluctuation in smaller subvolumes was quantified by calculating the root mean square deviation of a TAC about the gamma variate curve fit to the TAC data.Results:HYPR image sequences were produced using 2, 7, and 20 beat composite windows for the 250, 100, and 50 mA scans, respectively. At 25 and 10 mA, all available beats were used in the composite (41–60; average 50). A 7‐voxel‐wide 3D cubic filter kernel was used to form weighting images. The average ratio of HYPR voxel noise to 500‐mA FBP voxel noise was 1.06, 1.10, 0.97, 1.11, and 2.15 for HYPR scans at 250, 100, 50, 25, and 10 mA. The average limits‐of‐agreement between HYPR and FBP TAC values measured 0.02+/−0.91, 0.04+/−1.92, 0.19+/−1.59, 1.13+/−4.22, and 1.07+/−6.37 HU (mean difference +/−1.96 SD). The HYPR image subvolume that yielded a fixed level of TAC fluctuations was smaller, on average, than the FBP subvolume determined at the same mA.Conclusions:HYPR processing is a feasible method for generating low noise myocardial perfusion data from a low‐mA time‐resolved CT myocardial perfusion scan. The method is applicable to current clinical scanners and uses conventional image reconstructions as input data.
Renal Sympathetic Denervation for Treatment of Drug-Resistant Hypertension
Authors: Esler Murray D. , Krum Henry , Schlaich Markus , Schmieder Roland E. , Böhm Michael , Sobotka Paul A. 
Published: December 2012

Background—
Renal sympathetic nerve activation contributes to the pathogenesis of hypertension. Symplicity HTN-2, a multicenter, randomized trial, demonstrated that catheter-based renal denervation produced significant blood pressure lowering in treatment-resistant patients at 6 months after the procedure compared with control, medication-only patients. Longer-term follow-up, including 6-month crossover results, is now presented.

Methods and Results—

Eligible patients were on ≥3 antihypertensive drugs and had a baseline systolic blood pressure ≥160 mm Hg (≥150 mm Hg for type 2 diabetics). After the 6-month primary end point was met, renal denervation in control patients was permitted. One-year results on patients randomized to immediate renal denervation (n=47) and 6-month postprocedure results for crossover patients are presented. At 12 months after the procedure, the mean fall in office systolic blood pressure in the initial renal denervation group (−28.1 mm Hg; 95% confidence interval, −35.4 to −20.7;
P
<0.001) was similar to the 6-month fall (−31.7 mm Hg; 95% confidence interval, −38.3 to −25.0;
P
=0.16 versus 6-month change). The mean systolic blood pressure of the crossover group 6 months after the procedure was significantly lowered (from 190.0±19.6 to 166.3±24.7 mm Hg; change, −23.7±27.5;
P
<0.001). In the crossover group, there was 1 renal artery dissection during guide catheter insertion, before denervation, corrected by renal artery stenting, and 1 hypotensive episode, which resolved with medication adjustment.

Conclusions—
Control patients who crossed over to renal denervation with the Symplicity system had a significant drop in blood pressure similar to that observed in patients receiving immediate denervation. Renal denervation provides safe and sustained reduction of blood pressure to 1 year.

Clinical Trial Registration—

URL:
http://www.clinicaltrials.gov
. Unique identifier: NCT00888433.
Cirrus Cloud Properties and the Large-Scale Meteorological Environment: Relationships Derived from A-Train and NCEP–NCAR Reanalysis Data
Authors: Berry Elizabeth , Mace Gerald G. 
Published: December 2012

AbstractEmpirical knowledge of how cirrus cloud properties are coupled with the large-scale meteorological environment is a prerequisite for understanding the role of microphysical processes in the life cycle of cirrus cloud systems. Using active and passive remote sensing data from the A-Train, relationships between cirrus cloud properties and the large-scale dynamics are examined. Mesoscale cirrus events from along the A-Train track from 1 yr of data are sorted on the basis of vertical distributions of radar reflectivity and on large-scale meteorological parameters derived from the NCEP–NCAR reanalysis using a K-means cluster-analysis algorithm. With these defined regimes, the authors examine two questions: Given a cirrus cloud type defined by cloud properties, what are the large-scale dynamics? Vice versa, what cirrus cloud properties tend to emerge from large-scale dynamics regimes that tend to form cirrus? From the answers to these questions, the links between the large-scale dynamics regimes and the genre of cirrus that evolve within these regimes are identified. It is found that, to a considerable extent, the large-scale environment determines the bulk cirrus properties and that, within the dynamics regimes, cirrus cloud systems tend to evolve through life cycles, the details of which are not necessarily explained by the large-scale motions alone. These results suggest that, while simple relationships may be used to parameterize the gross properties of cirrus, more sophisticated parameterizations are required for representing the detailed structure and radiative feedbacks of these clouds.
Modulation of the Diurnal Cycle of Warm-Season Precipitation by Short-Wave Troughs
Authors: Tuttle John D. , Davis Chris A. 
Published: December 2012

Abstract
Traveling deep tropospheric disturbances of wavelengths ~1500 km (short waves) have long been known to play an important role in the initiation and maintenance of warm-season convection. To date, relatively few studies have formally documented the climatology of short waves and their relationship to the diurnal heating cycle, the topography, and the diurnal cycle of precipitation. Those that did had to rely on low-resolution global analyses and often could not track short waves across mountain barriers. In this study, 10 yr of the (32 km) NCEP North American Regional Reanalysis (NARR) are used to objectively identify and track short waves in the North American domain. Statistics of short-wave span, duration, phase speed, latitudinal extent, and locations of preferred intensification/decay are presented. Some of the key findings from the climatology include that the lee (windward) of mountain barriers are preferred regions of intensification (decay) and short waves show little evidence of a diurnal cycle and can pass a given point at any time of the day. The second part of the study focuses on the role that short waves play in modulating the diurnal cycle of propagating convection east of the Rocky Mountains. Depending on the timing of short-wave passage, short waves may either significantly enhance the precipitation above the mean or completely disrupt the normal diurnal cycle, causing precipitation to develop at times and locations where it normally does not. While short waves play an important role in modulating the mean precipitation patterns their role is considered to be secondary in nature. The diurnal precipitation signature is prominent even when short waves are not present.