bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural transitions of nanocrystalline domains in regioregular poly(3‐hexyl thiophene) thin films
Authors: Yang Hoichang , Joo Shin Tae , Bao Zhenan , Ryu Chang Y. 
Published: April 2007

AbstractThe effects of solution processing and thermal annealing on thin film morphology and crystalline structures of regioregular poly(3‐hexyl thiophene) (RR P3HT) are studied in terms of molecular weight (Mw). Using grazing‐incidence X‐ray diffraction, π‐conjugated planes in drop‐cast films from chloroform solutions are found to be preferentially oriented parallel to the substrates regardless of Mw. However, the mesoscale nanocrystalline morphology of the drop‐cast films is significantly affected by Mw, exhibiting a distinctive morphological transition from short nanorods to long nanofibrils above a critical number‐averaged Mw (∼ 3.6 kDa). This is probably due to the change in a conformation change from an extended‐chain to a folded‐chain, as Mw of RR P3HT increases. In contrast, spin‐casting of high Mw RR P3HT produces less ordered films with a lower crystallinity and mixed parallel/perpendicular orientations of π‐conjugated planes. The crystallinity and parallel π‐conjugated orientation of RR P3HT in spin‐cast films could be improved by thermal treatments at high‐temperatures either (1) above the glass transition temperature or (2) above the melting temperature of RR 3PHT followed by recrystallization upon cooling under vacuum. However, the charge mobility of the spin‐cast films for a field‐effect transistor application is still lower than that of the drop‐cast films. This would be attributed to the chain oxidation and the development of distinct grain boundaries between RR P3HT nanofibrils during the thermal treatments. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1303–1312, 2007
Structural aspects and the conduction mechanism of Ln(Ba2–xPrx)Cu3O7+δ (Ln = Tm, Lu)
Authors: Mokhtari Z. , Akhavan M. 
Published: April 2007

AbstractTmBa2–x Prx Cu3O7+δ and LuBa2–x Prx Cu3O7+δ samples with 0.0 < x ≤ 1.0 have been prepared by a solid‐state reaction technique. The occurrence of the orthorhombic to tetragonal phase transition, increasing of oxygen content with the increase of Pr doping, and the existence of solubility limit in both systems confirm the correct substitution of Pr at Ba sites. The solubility limit for Pr in the Lu‐based samples is less than 0.7, which is less than x = 0.90 for the Tm‐based samples. The Tc depression versus doping content in both systems shows that depression of superconductivity by Pr at Ba sites is mostly due to the hole‐filling/localization effects. Also, in the Tm‐based system, the metal–insulator transition occurs at xcMIT ≈ 0.30, and the superconductor–insulator transition occurs at xcSIT = 0.45, but in the Lu‐based system, xcMIT ≈ 0.35 and xcSIT = 0.50. In the normal state, for both systems with x < xcMIT, the Coulomb gap phase is dominant, whereas for the samples with Pr content xcMIT ≤ x < xccSIT, two‐dimensional variable‐range hopping, and for x > xcSIT, three‐dimensional variable‐range hopping are the dominant conduction mechanisms. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spin‐ and charge‐density excitations in quantum dots via Quantum Monte Carlo simulation
Authors: Colletti Leonardo , Pederiva Francesco , Lipparini Enrico , Umrigar Cyrus J. 
Published: April 2007

AbstractThe calculation of the polarizability provides a method of calculating the collective‐modes excitation energies of an electronic system. However, the polarizability is a correlated quantity, thus demanding a major effort when Monte Carlo methods are used for its evaluation. Nevertheless, Quantum Monte Carlo results represent the benchmark in most many‐body physics. We applied a correlated Variational and Diffusion Monte Carlo scheme to a GaAs–AlGaAs quantum dot. Comparison with Raman scattering experiments and previous calculations is considerable. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Role of localized donor states in transport and photoluminescence of InN revealed by hydrostatic pressure studies
Authors: Suski T. , Kamińska A. , Franssen G. , Teisseyre H. , Dmowski L. H. , Plesiewicz J. A. , Lu H. L. , Schaff W. J. , Kurouchi M. , Nanishi Y. 
Published: April 2007

AbstractPressure‐dependent transport and photoluminescence (PL) measurements were performed on InN. In the transport measurements on the sample with a low electron concentration (ne lower than about 1018 cm–3) a Localized Donor State (LDS) was seen to cross the Fermi level at elevated pressure magnitude. It was accompanied by the transfer of electrons from the Conduction Band to the LDS and a significant increase in electron mobility. In a sample with a higher concentration of electrons no transport anomaly was observed. Application of pressure helps to confirm that the disputed photoluminescence mechanism in InN consists in band‐to‐band recombination. No evidence of the participation of this LDS in radiative recombination processes was found in the pressure‐dependent PL measurements. On the contrary, the dependence of the PL intensity on excitation power suggested the involvement of the LDS in nonradiative recombination processes. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Preface: phys. stat. sol. (b) 244/5
Authors: Zakrzewski Adam J. 
Published: April 2007

AbstractThe Symposium F of the 2006 E‐MRS Fall Meeting (held in Warsaw, Poland, on 4–8 September 2006) was organized to cover many important aspects of basic and applied research of wide‐bandgap II–VI compounds and their alloys. Emphasis was given to new technological and application concepts concerning both bulk crystals and various quantum structures with reduced dimensionality, ranging from zero (quantum dots) to two (quantum well structures) dimensions. The presented results on application‐oriented materials were mostly focused on light emitting structures, light and X‐ray detectors, as well as materials for spintronics. Special attention was given to technological aspects and challenges: growth techniques, defect control and structure optimization, doping procedures, optical properties and degradation processes. Relevant experimental techniques employed in these studies were also discussed. Experimental results were compared with theoretical calculations giving deeper insight into many problems of modern material science. Over 60 researchers from all over the world participated at this Symposium giving in all 9 invited lectures, 20 oral talks, and 50 poster presentations.
Modified atmosphere packaging of fresh meats–sudden partial adaptation caused an increase in sustainability of dutch supply chains of fresh meats
Authors: Thoden van Velzen E. U. , Linnemann A.R. 
Published: April 2007

AbstractIn the past decade, a major transition evolved in the Dutch fresh meat industry with ramifications for the entire meat business. In 1995, more than 95% of all fresh meat products for consumers were either sold loose or packed in the traditional way, i.e. on a white styrofoam tray with stretch wrap. Almost a decade later, about half of the meat industry has adapted the modified atmosphere packaging (MAP) technology. Strikingly, the first trials with this technology had already been conducted in The Netherlands in 1964, but it took four decades for the technology to conquer the Dutch meat industry. This paper argued that the partial adaptation of MAP diminished the product losses in fresh meat sales and hence the environmental impact of meat production and consumption. Copyright © 2007 John Wiley & Sons, Ltd.
New index functions for storing Gaunt coefficients
Authors: Pinchon Didier , Hoggan Philip E. 
Published: April 2007

AbstractGaunt coefficients express angular momentum conservation rules. They are therefore required in the combination of atomic orbitals. In this case, the angular factors are spherical harmonics and the Gaunt coefficients appear when their products are linearized. The Gaunt coefficients may be pre‐calculated and stored. This work describes new index functions for storing and retrieving the required Gaunt coefficients that are (almost) all nonzero. This strategy is closely related to that of Rasch and Yu, who have compared retrieval to that using recurrence relations and found it to be at least 20 times faster. Some improvements to their work will be found here and the index functions used are different. Only a few arithmetic operations are required to generate the index; therefore, its evaluation and handling takes a negligible time compared to its applications, notably molecular electronic integral evaluation. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
Second‐order sliding mode control of underactuated mechanical systems II: Orbital stabilization of an inverted pendulum with application to swing up/balancing control
Authors: Santiesteban Raul , Floquet Thierry , Orlov Yury , Riachy Samer , Richard Jean‐Pierre 
Published: April 2007

AbstractOrbital stabilization of an underactuated cart–pendulum system is under study. The quasihomogeneous control synthesis is utilized to design a second‐order sliding mode controller that drives the actuated cart to a periodic reference orbit in finite time, while the non‐actuated pendulum produces bounded oscillations. A modified Van der Pol oscillator is introduced into the synthesis as an asymptotic generator of the periodic motion. The resulting closed‐loop system is capable of moving from one orbit to another by simply changing the parameters of the Van der Pol modification. Performance issues of the proposed synthesis are illustrated in numerical and experimental studies of the swing up/balancing control problem of moving a pendulum, located on an actuated cart, from its stable downward position to the unstable inverted position and stabilizing it about the vertical. Copyright © 2007 John Wiley & Sons, Ltd.
Teachers' perceptions of policy influences on science instruction with culturally and linguistically diverse elementary students
Authors: Shaver Annis , Cuevas Peggy , Lee Okhee , Avalos Mary 
Published: April 2007

AbstractThis study asked elementary school teachers how educational policies affected their science instruction with a majority of English language learners. The study employed a questionnaire followed by focus group interviews with 43 third and fourth grade teachers from six elementary schools in a large urban school district with high populations of English language learners in the southeastern United States. Results indicate that teachers' opinions concerning all areas of policy evolved as the state enforced stronger measures of accountability during the 2‐year period of the study. Although relatively positive regarding standards, their opinions became increasingly negative regarding statewide assessment, and even more so toward accountability measured by reading, writing, and mathematics. The results suggest that it is important to understand how teachers perceive the influence of policies, particularly those relating to English language learners, as science accountability becomes more imminent across the states. © 2007 Wiley Periodicals, Inc. J Res Sci Teach 44: 725–746, 2007
Decolonizing methodologies and indigenous knowledge: The role of culture, place and personal experience in professional development
Authors: Chinn Pauline W.U. 
Published: April 2007

AbstractThis study reports findings from a 10‐day professional development institute on curricular trends involving 19 secondary mathematics and science teachers and administrators from Japan, Malaysia, Indonesia, Thailand, Korea, Philippines, the United States, and People's Republic of China. Participants explored the roles of culture, place, and personal experience in science education through writings and group discussions. Initially, Asian participants tended to view indigenous knowledge and practices more negatively than U.S. peers. After a presentation on indigenous Hawaiian practices related to place and sustainability, they evaluated indigenous practices more positively and critiqued the absence of locally relevant science and indigenous knowledge in their national curricula. They identified local issues of traffic, air, and water quality they would like to address, and developed lessons addressing prior knowledge, place, and to a lesser extent, culture. These findings suggested critical professional development employing decolonizing methodologies articulated by indigenous researchers Abbott and Smith has the potential to raise teachers' awareness of the connections among personal and place‐based experiences, cultural practices and values, and teaching and learning. An implication was the development of a framework for professional development able to shift science instruction toward meaningful, culture, place, and problem‐based learning relevant to environmental literacy and sustainability. © 2007 Wiley Periodicals, Inc. J Res Sci Teach 44: 1247–1268, 2007
Impact of Preoperative Planning Using Virtual Segmental Volumetry on Liver Resection for Hepatocellular Carcinoma
Authors: Yamanaka Junichi , Saito Shinichi , Fujimoto Jiro 
Published: April 2007

AbstractBackgroundAccurate assessment of resection volume and vascular anatomy is mandatory in preoperative planning for safe and curative hepatectomy to treat cancer. Accordingly, we examined feasibility and accuracy of a preoperative three‐dimensional (3D) computed tomography (CT) scan based simulation in patients with impaired liver function undergoing hepatectomy for hepatocellular carcinoma (HCC).MethodsHepatectomy simulation software was programmed to reconstruct detailed 3D vascular structure and calculate liver volume based on hepatic circulation. In 113 patients with HCC, liver resection volume was estimated preoperatively by both simulation and conventional planimetry. For validation, predicted resection volumes were compared with actual resected specimen weights. The resection margin as estimated by the simulation was compared with the margin in the specimen.ResultsSimulation showed higher correlation and smaller discrepancy (r = 0.96; 9.3 ml) between predicted and actual liver resection volume than conventional planimetry (r = 0.74; 174 ml). Simulation showed correlation (p < 0.01) between estimated and actual segmental volume, which was not measurable by planimetry. Simulation showed a correlation (r = 0.84) between predicted and actual margin, with a difference of 1.6 mm.ConclusionsHepatectomy simulation in 3D predicted segmental liver volume and the resection margin accurately. This virtual method should contribute to preoperative planning to achieve safe, curative resection in HCC patients, whose hepatic function is compromised.
Extranodal Tumor Extension to Adjacent Organs Predicts a Worse Cause‐specific Survival in Patients with Papillary Thyroid Carcinoma
Authors: Ito Yasuhiro , Hirokawa Mitsuyoshi , Jikuzono Tomoo , Higashiyama Takuya , Takamura Yuuki , Miya Akihiro , Kobayashi Kaoru , Matsuzuka Fumio , Kuma Kanji , Miyauchi Akira 
Published: April 2007

AbstractBackgroundWe previously reported that massive extrathyroid extension has an independent prognostic value in patients with thyroid papillary carcinoma. However, tumor extension to adjacent organs can be observed not only in primary tumor but also in metastatic nodes. In this study we investigated the clinical significance of extranodal tumor extension to adjacent organs (nodal ex) in papillary thyroid carcinoma.MethodsWe classified all cases into three categories based on the degree of nodal ex: nodal ex0, no apparent extranodal tumor extension; nodal ex1, hard metastatic nodes with perinodal growth extending to adjacent organs, which require separation of the nodes from the organs; and nodal ex2, metastatic nodes with perinodal growth completely invading the adjacent organs and requiring excision of nodes together with these organs. We investigated the clinical significance of each grade in 1,692 patients who underwent initial surgery for papillary carcinoma between 1987 and 1995.ResultsThe presence of nodal ex was significantly linked to various clinicopathological features such as male gender, N1b, large number of metastatic nodes, pT4a, and distant metastasis. On univariate analysis, patients with either nodal ex1 or ex2 showed significantly worse disease‐free and cause‐specific survival rates, although these rates did not differ between patients with nodal ex1 and those with nodal ex2. Furthermore, multivariate analysis demonstrated that nodal ex independently predicts worse cause‐specific survival of these patients.ConclusionsPresence of nodal ex significantly reflects the biologically aggressive behaviors of papillary carcinoma and has a prognostic value, especially for cause‐specific survival of patients.
Study of Efficacy of Bilayer Mesh Device versus Conventional Polypropelene Hernia System in Inguinal Hernia Repair: Early Results
Authors: Chauhan Ashutosh , Tiwari Sangeeta , Gupta Ashok 
Published: April 2007

AbstractBackgroundThe Prolene hernia system (PHS) is a three‐dimensional mesh device that combines three approaches to hernia repair, but its high cost precludes its widespread use in developing countries. We describe our experience with an indigenous bilayer mesh device that works on a similar principle, and compare its efficacy with conventional PHS.Materials and MethodsA total of 84 patients with unilateral/bilateral primary uncomplicated inguinal hernia were recruited for the study over a 1‐year period and randomized into two groups. Group 1, which consisted of 40 patients, received the indigenous device, and group 2, 44 patients, received conventional PHS. Mean operative time and the patients’ visual assessment scores (VAS) for pain were primary outcome measures. Patient were reviewed in out patients department at intervals of 3 months, and the incidence of complications and recurrence was noted. This was the secondary outcome measure.ResultsThe two group were comparable in terms of age, type of hernia, and mean duration of follow‐up. The mean operative time was 32.1 min (± 5.5) and 33.25 (± 5.3) in groups 1 and 2, respectively, and the mean VAS score was 2.25 and 2.27 in the respective groups. There was no statistically significant difference. Similarly, the was no significant difference in incidence of complications noted between the two groups (3/40 versus 4/44, respectively). There were no recurrences noted during the period of observation.ConclusionsThe indigenous bilayer device described in this study combines the advantages of two well‐publicized techniques of hernia repair: inlay repair and onlay repair. It offers the benefits of conventional PHS repair but is far less expensive and is quite suitable for routine use in centers like ours in a developing nation, where financial resources are a constraint.
Genetic approaches to human renal agenesis/hypoplasia and dysplasia
Authors: Sanna-Cherchi Simone , Caridi Gianluca , Weng Patricia L. , Scolari Francesco , Perfumo Francesco , Gharavi Ali G. , Ghiggeri Gian Marco 
Published: April 2007

AbstractCongenital abnormalities of the kidney and urinary tract are frequently observed in children and represent a significant cause of morbidity and mortality. These conditions are phenotypically variable, often affecting several segments of the urinary tract simultaneously, making clinical classification and diagnosis difficult. Renal agenesis/hypoplasia and dysplasia account for a significant portion of these anomalies, and a genetic contribution to its cause is being increasingly recognized. Nevertheless, overlap between diseases and challenges in clinical diagnosis complicate studies attempting to discover new genes underlying this anomaly. Most of the insights in kidney development derive from studies in mouse models or from rare, syndromic forms of human developmental disorders of the kidney and urinary tract. The genes implicated have been shown to regulate the reciprocal induction between the ureteric bud and the metanephric mesenchyme. Strategies to find genes causing renal agenesis/hypoplasia and dysplasia vary depending on the characteristics of the study population available. The approaches range from candidate gene association or resequencing studies to traditional linkage studies, using outbred pedigrees or genetic isolates, to search for structural variation in the genome. Each of these strategies has advantages and pitfalls and some have led to significant discoveries in human disease. However, renal agenesis/hypoplasia and dysplasia still represents a challenge, both for the clinicians who attempt a precise diagnosis and for the geneticist who tries to unravel the genetic basis, and a better classification requires molecular definition to be retrospectively improved. The goal appears to be feasible with the large multicentric collaborative groups that share the same objectives and resources.
Space–time patterns during the establishment of a nonindigenous species
Authors: Tobin Patrick C. 
Published: April 2007

AbstractIncreasing rates of global trade and travel have the invariable consequence of an increase in the likelihood of nonindigenous species arrival, and some new arrivals are successful in establishing themselves. Quantifying the pattern of establishment of nonindigenous species across both spatial and temporal scales is paramount in early detection efforts, yet very difficult to accomplish. Previous work in epidemiology has proposed methods for assessing the space–time properties of emerging infectious diseases by quantifying the degree of space–time clustering between individual cases. I tested the applicability of one such method commonly used in epidemiology, the Knox test for space–time interaction, to analyze rare abundance data from an isolated, newly‐establishing gypsy moth,Lymantria dispar, population in Minnesota, USA, and incorporated a bootstrap approach to quantify the space–time pattern in a random process that can be used to compare with results from empirical data. The use of the Knox test in assessing the establishment phase of biological invasions could potentially serve as an early warning system against new invaders, particularly for those with a known history of a repeated number of arrivals.
A systems framework for understanding social settings
Authors: Tseng Vivian , Seidman Edward 
Published: April 2007

AbstractIn this paper, we argue that attempts to change social settings have been hindered by lack of theoretical advances in understanding key aspects of social settings and how they work in a dynamic system. We present a systems framework for understanding youths' social settings. We focus on three aspects of settings that represent intervention targets: social processes (i.e., patterns of transactions between two or more people or groups of people), resources (i.e., human, economic, physical, temporal resources), and organizationof resources (i.e., how resources are arranged and allocated). We postulate that these setting aspects are in dynamic transaction with each other, resulting in setting outcomes. Discussion focuses on the implications of our theoretical framework for setting intervention.
Developing operating principles for systems change
Authors: Behrens Teresa R. , Foster-Fishman Pennie G. 
Published: April 2007

AbstractBased on an analysis of the articles in this special issue, the authors propose five operating principles for systems change work. These principles are: clarifying the purpose of the systems change; identifying whether the change is one to an existing system or the change is to create a new system; conceptualize the work as systems change from the beginning; use an eclectic approach; and be open to opportunities that emerge while also undertaking forma analysis to identify leverage points. The authors argue that the time is now ripe to develop such principles and encourage community change agents to engage in a dialogue to explore, revise, eliminate or expand on these principles.