bluuebunny/crossref_metadata_2025_split huggingface dataset:
Competition in the sandbox: A test of the effects of preschool competition on educational outcomes
Authors: Henry Gary T. , Gordon Craig S. 
Published: November 2005

AbstractThe emergence of publicly subsidized preschool raises important policy questions about the role of market forces and, in places where competition to provide these services exists, presents a setting in which the effects of competition on educational outcomes can be tested. We test neo‐institutional hypotheses concerning the effects of competition to provide publicly‐funded prekindergarten (pre‐k) services on the performance of public schools and private organizations. We use student‐level data collected over a five‐year period on a large sample of children who attended publicly subsidized prekindergarten in Georgia. Overall, we find that more competition improves third grade reading and math test scores but does not significantly affect retention or school readiness ratings during elementary school. Not all children are equally affected by competition; for example, greater competition significantly decreases the likelihood of retention for children of the working poor. Contrary to the expectations of some theorists, both public schools and private organizations respond to increased competition in ways that improve test scores but not retention. However, children attending private prekindergarten have higher language arts scores and lower retention across the range of competition when compared with children who attended public school pre‐k. © 2006 by the Association for Public Policy Analysis and Management
The impact of kindergarten entrance age policies on the childcare needs of families
Authors: Datar Ashlesha 
Published: November 2005

AbstractThe past two decades have seen a rising trend in the minimum entrance age for kindergarten in the U.S. A little‐noticed, but potentially large, consequence of raising the minimum entrance age is that it imposes additional childcare costs for families whose children are forced to stay out of school for an additional year. This paper develops a model for parents' kindergarten entrance age decisions and examines the relationship between socio‐economic factors and parents' desired entrance age for their child using a nationally representative dataset on kindergartners in the U.S. The estimates from this model are used to simulate the impact of alternate changes in kindergarten entrance age policies on the number and characteristics of children affected by the policy change, and to estimate the additional childcare cost burden from the policy change. © 2006 by the Association for Public Policy Analysis and Management
Comparison of conventional to intensity modulated radiation therapy for abdominal neuroblastoma
Authors: Paulino Arnold C. , Ferenci Michele S. , Chiang Kuang‐Yueh , Nowlan Adam W. , Marcus Robert B. 
Published: November 2005

AbstractObjectiveTo compare three different techniques of irradiating abdominal neuroblastoma.Patients and MethodsSix children with a median age of 4.1 years underwent radiotherapy (RT) to the primary site as part of treatment for high‐risk neuroblastoma. Four had midline disease while two had well‐lateralized lesions. Three different RT techniques were compared. Technique A used parallel‐opposed AP/PA fields prescribed to the midplane of the patient. For Techniques B and C, intensity modulated radiation therapy (IMRT) plans were developed using inverse treatment planning with a sliding window or dynamic multileaf collimator approach, seven coplanar beams, and a 0.25 × 0.5 cm minimum beam resolution. The clinical target volume (CTV) included the tumor present prior to second look surgery but after induction chemotherapy with a 1.5 cm margin. The planning target volume (PTV) was the CTV with a 0.5 cm margin. The CTV was planned to receive 100% of the prescribed dose. For Technique C, the vertebral bodies adjacent to the tumor were included in the PTV to minimize heterogeneity of dose. Six MV photons were used for all techniques. Bilateral kidneys, liver, spine, spleen, stomach and bilateral iliac crests were contoured.ResultsDose to the PTV and CTV were not significantly different using the three techniques. In comparison to Technique A, Techniques B and C delivered a lower mean dose to the bilateral kidneys in the four children with midline tumors but not the two children with a lateralized tumor where the contralateral kidney received a higher mean dose. Dose to the spine was less homogeneous with Technique B compared to Techniques A and C. The spleen, liver and stomach mean doses were higher using Techniques B and C compared to Technique A.ConclusionAlthough Technique C was the best method of RT delivery in midline tumors with respect to kidney doses, this was at a cost of a higher mean dose to the liver, stomach, and spleen. This, together with the theoretical increase in secondary malignancies, should be considered when treating a child with IMRT techniques. IMRT was not found to be better than the conventional AP/PA field for lateralized tumors. Pediatr Blood Cancer © 2005 Wiley‐Liss, Inc.
Polyamide‐6/natural clay mineral nanocomposites prepared by solid‐state shear milling using pan‐mill equipment
Authors: Shao Weiguo , Wang Qi , Wang Feng , Chen Yinghong 
Published: November 2005

AbstractThe polyamide‐6 (PA6)/natural clay mineral nanocomposites were successfully prepared by solid‐state shear milling method without any treatment of clay mineral and additives. PA6/clay mixture was pan‐milled to produce PA6/clay compounding powder, using pan‐mill equipment. The obtained powder as master batch was diluted with neat PA6 to prepare composites by a twin‐screw extruder. The clay silicate layers were found to be partially exfoliated and dispersed homogeneously at nanometer level in PA6 matrix. The rheological measurements and mechanical properties of nanocomposites were characterized. The shear viscosities of nanocomposites were higher than that of pure PA6, and tensile strength and tensile modulus increased, but Izod impact strength decreased, with increasing concentration of clay. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 249–255, 2006
Peptide fragment studies on the folding elements of dihydrofolate reductase from Escherichia coli
Authors: Arai Munehito , Iwakura Masahiro 
Published: November 2005

AbstractOne of the necessary conditions for a protein to be foldable is the presence of a complete set of “folding elements” (FEs) that are short, contiguous peptide segments distributed over an amino acid sequence. The FE‐assembly model of protein folding has been proposed, in which the FEs play a role in guiding structure formation through FE–FE interactions early in folding. However, two major issues remain to be clarified regarding the roles of the FEs in determining protein foldability. Are the FEs AFUs that can form nativelike structures in isolation? Is the presence of only the FEs without mutual connections a sufficient condition for a protein to be foldable? Here, we address these questions using peptide fragments corresponding to the FEs of DHFR from Escherichia coli. We show by CD measurement that the FE peptides are unfolded under the native conditions, and some of them have the propensities toward non‐native helices. MD simulations also show the non‐native helical propensities of the peptides, and the helix contents estimated from the simulations are well correlated with those estimated from the CD in TFE. Thus, the FEs of DHFR are not AFUs, suggesting the importance of the FEs in nonlocal interactions. We also show that equimolar mixtures of the FE peptides do not induce any structural formation. Therefore, mutual connections between the FEs, which should strengthen the nonlocal FE–FE interactions, are also one of the necessary conditions for a protein to be foldable. Proteins 2006. © 2005 Wiley‐Liss, Inc.
Determination of the enantiomer fraction of PBB 149 by gas chromatography/electron capture negative ionization tandem mass spectrometry in the selected reaction monitoring mode
Authors: von der Recke Roland , Mariussen Espen , Berger Urs , Götsch Arntraut , Herzke Dorte , Vetter Walter 
Published: November 2005

AbstractEnantioselective determination of the atropisomers of 2,2′,3,4′,5′,6‐hexabromobiphenyl (PBB 149) in a purified sample from a bird egg was attempted in this work. By application of the classic method for PBB determination, i.e. gas chromatography coupled to electron capture negative ionization mass spectrometry (GC/ECNI‐MS) using the bromide ions, the enantiomers interfered with another brominated compound. Subsequent measurements clarified that this interference did not occur in the mass chromatogram of the molecular ion of PBB 149. Therefore, a GC/ECNI tandem mass spectrometry (MS/MS) method was developed, based on the fragmentation of [M]−. A suitable precursor‐product ion transition was found for m/z 627.5 → 80 ± 1.5, representing the most abundant ion trace of the molecular ion and the bromide ions. Optimization of the ion source temperature, the methane gas pressure, and the collision voltages resulted in a robust method that could solve the problem. Subsequent injections of a technical PBB product (Firemaster BP‐6®) resulted in the anticipated racemic proportion (enantiomer fraction (EF) = 0.50 ± 0.02 (n = 8)). By contrast, the EF in the purified extract of a bird egg was found to be 0.42 ± 0.02 (n = 10), indicative of a significant enantioenrichment of the second eluting atropisomer. Additional measurements were performed on a non‐chiral column. These measurements allowed for the detection of 16 hexabromobiphenyls (hexa‐BBs) in Firemaster BP‐6®. These comparisons verified that PBB 149 enantiomers did not interfere with an isomer that could falsify the enantiomer fraction in the sample. The novel method using GC/ECNI‐MS/MS in the selected reaction monitoring (SRM) mode was eight times more sensitive than application of conventional GC/ECNI‐MS selected ion monitoring (SIM) analysis of the molecular ion. Copyright © 2005 John Wiley & Sons, Ltd.
Who competes with whom? A demand‐based perspective for identifying and representing asymmetric competition
Authors: DeSarbo Wayne S. , Grewal Rajdeep , Wind Jerry 
Published: November 2005

AbstractA host of strategic management and marketing issues, including competitive analysis and strategic decision making, hinges on accurately identifying and representing competitive market structures. It is readily acknowledged that competitive market structures are typically asymmetric; namely, one firm may actively compete with another in a given market but not vice versa. However, empirical efforts to assess these competitive asymmetries have been lacking in the strategy literature. We propose a new spatial methodology to identify and represent asymmetric competitive market structures. Specifically, we devise a new stochastic multidimensional scaling procedure that is calibrated from actual consumer consideration/choice sets to estimate and uncover competitive asymmetries. The proposed methodology can be effectively employed in the analysis of appropriate data from either demand‐ or supply‐side approaches to assess competitive market structure. We illustrate our proposed methodology with survey data collected from two different commercial applications: one from the U.S. luxury automobile market and the other from the U.S. portable telephone market. We contrast the findings of the proposed methodology against traditional symmetric approaches for identifying and representing competitive market structures, and discuss the respective strategic insights. Copyright © 2005 John Wiley & Sons, Ltd.
Open for innovation: the role of openness in explaining innovation performance among U.K. manufacturing firms
Authors: Laursen Keld , Salter Ammon 
Published: November 2005

AbstractA central part of the innovation process concerns the way firms go about organizing search for new ideas that have commercial potential. New models of innovation have suggested that many innovative firms have changed the way they search for new ideas, adopting open search strategies that involve the use of a wide range of external actors and sources to help them achieve and sustain innovation. Using a large‐scale sample of industrial firms, this paper links search strategy to innovative performance, finding that searching widely and deeply is curvilinearly (taking an inverted U‐shape) related to performance. Copyright © 2005 John Wiley & Sons, Ltd.
Alkaliisocyanacetate. Synthese und Struktur von [K(18‐Krone‐6)](O2CCH2NC)
Authors: Fehlhammer Wolf Peter , Schrölkamp Stephan , Hoyer Michael , Hartl Hans , Beck Wolfgang 
Published: November 2005

AbstractAlkali‐isocyanoacetates. Synthesis and Structure of [K(18‐crown‐6)](O2CCH2NC)The alkali isocyanoacetates M+[O2CCH2NC]− (M = Li,Na,K,Cs) (1a‐d) are synthesized by reaction of ethyl isocyanoacetate with the respective alkali hydroxides in ethanol and characterized by IR, NMR (1H, 13C), and mass spectrometry (FAB). In alcoholic solution as well as in the gas phase ion pairs and higher aggregated species are observed. In contrast, [K(18‐crown‐6)][O2CCH2NC] (2) which is obtained from 1c and 18‐crown‐6, turns out to be a 1:1 electrolyte in solution (acetone); in the solid, the isocyanoacetate anion binds to K+ via the two carboxylate oxygen atoms resulting in an O8‐coordinated metal atom.
Crystal Structure of Guanylurea Sulphate Hydrate [H2NC(=O)NHC(NH2)2]2SO4 · 2 H2O
Authors: Lotsch Bettina V. , Schnick Wolfgang 
Published: November 2005

AbstractSingle crystals of guanylurea (1–carbamoylguanidinium) sulphate hydrate (C 2/c, a = 30.353(6), b = 6.6162(13), c = 21.204(4) Å, β = 99.37(3)°, V = 4201.4(14) Å3, T = 200 K) were obtained from a neutral aqueous solution containing guanylurea sulphate. By analogy with previously reported simple molecular guanylurea salts, the title compound builds up an array of mutually linked chains of cations and anions, with the crystal packing being largely controlled by an extensive hydrogen bonding network.
Syntheses and Structural Characterization of Two Nitrilotriacetate Cobalt Complexes: [{CoK2(NTA)(Hmta)(H2O)3}NO3]n and [{Co(4,4′‐bpy)2(H2O)4}{Co2(NTA)2(4,4′‐bpy)(H2O)2}]
Authors: Chen Zilu , Liang Fupei , Tang Xingfu , Chen Mansheng , Song Lihua , Hu Ruixiang 
Published: November 2005

AbstractTwo nitrilotriacetate cobalt complexes {[CoK2(NTA)(Hmta)(H2O)3]NO3}n (1) and [{Co(4,4′‐bpy)2(H2O)4}{Co2(NTA)2(4,4′‐bpy)(H2O)2}] (2) (NTA = nitrilotriacetate anion, Hmta = hexamethylenetetramine and 4,4′‐bpy = 4,4′‐bipyridine) were prepared and characterized by IR, elemental analysis and single crystal X‐ray diffraction study. The influence of the neutral ancillary ligands on the formation of the complexes with different structures in the Co‐NTA system was discussed. The coordination of NTA and Hmta to Co2+ ions only resulted in the formation of mononuclear [Co(NTA)(Hmta)]− ions which are further connected by K+ ions and water molecules to form a three‐dimensional network. The use of 4,4′‐bpy as ancillary ligand in 2 led to the formation of separate mononuclear [Co(4,4′‐bpy)2(H2O)4]2+ and dinuclear [Co2(NTA)2(4,4′‐bpy)(H2O)2]2− which are further connected by hydrogen bonds to form a supramolecular three‐dimensional network. In these cases it seems to suggest that the addition of neutral ancillary ligand into the Co‐NTA system leads to the formation of lower dimensional structures when the contribution of alkali ions to the structural dimensionality is neglected.
Pt6Cl12·(1,2,4‐C6H3Cl3), a Structurally Characterized Cocrystallization Product of Pt6Cl12
Authors: Gorlov Mikhail , Fischer Andreas , Kloo Lars 
Published: November 2005

AbstractThe reaction of platinum(II) chloride with 1,2,4‐trichlorobenzene gives the novel platinum complex Pt6Cl12·(1,2,4‐C6H3Cl3). It is the first example of an cocrystallization product of platinum(II) chloride and organic molecules whose crystal structure has been established.
Grid‐like Cobalt(II) Layered Complex with an Unprecedented Double 1,2‐Bis(1,2,4‐triazole‐1‐yl)methane Bridges
Authors: Chen Xiao‐Yan , Cheng Peng , Yan Shi‐Ping , Liao Dai‐Zheng , Jiang Zong‐Hui 
Published: November 2005

AbstractA novel two‐dimensional cobalt complex, [Co(btrm)2(dca)]ClO4 (1, btrm = 1,2‐bis(1,2,4‐triazole‐1‐yl)methane, dca = dicyanamide), was synthesized and characterized. X‐ray diffraction analyses reveal that the title complex crystallizes in the monoclinic space group C2/m with a = 29.507(13)Å, b = 17.804(8) Å, c = 14.709(7) Å, β = 119.916(7)°, Z = 12, and R1 = 0.0784, wR2 = 0.2041. The cobalt atom involves a six‐coordinated CoN6 environment, with a distorted octahedral coordination. Two btrm ligands connect the CoII atoms with the exodentate nitrogen atoms on the 4‐position of triazole rings to form a sixteen‐membered rhombic grid. The unprecedented double btrm bridges and μ1,5‐dca bridge connect the cobalt atoms to form a two‐dimensional grid‐like layered structure. The spectroscopic and magnetic properties have also been investigated.
The association between suicide and the socio-economic characteristics of geographical areas: a systematic review
Authors: REHKOPF DAVID H. , BUKA STEPHEN L. 
Published: November 2005

Background. Despite an extensive literature, there have been widely divergent findings regarding the direction of the association between area socio-economic characteristics and area suicide rates, with high-quality studies finding either a direct relation (higher rates of suicide in higher socio-economic areas), an inverse relation (lower rates of suicide in higher socio-economic areas) or no association.Method. We performed a systematic review of the literature dating from 1897 to 2004 and identified 86 publications with 221 separate analyses that met our inclusion criteria. We examined the percent of direct, inverse and null findings stratified by key study characteristics including size of aggregated area, socio-economic measure used, region of study, control variables and study design.Results. Analyses at the community level are significantly more likely to demonstrate lower rates of suicide among higher socio-economic areas than studies using larger areas of aggregation. Measures of area poverty and deprivation are most likely to be inversely associated with suicide rates and median income is least likely to be inversely associated with suicide rates. Analyses using measures of unemployment and education and occupation were equally likely to demonstrate inverse associations. Study results did not vary significantly by gender or by study design.Conclusions. The heterogeneity of associations is mostly accounted for by study design features that have largely been neglected in this literature. Enhanced attention to size of region and measurement strategies provide a clearer picture of how suicide rates vary by region. Resources for suicide prevention should be targeted to high poverty/deprivation and high unemployment areas.
SHOULD CITIZENS OF A WELFARE STATE BE TRANSFORMED INTO “QUEENS”?
Authors: RISSE MATHIAS 
Published: November 2005

Motivation, agency, and public policy: of knights and knaves, pawns and queens, by Julian Le Grand, Oxford University Press, 2003, 230 pages.Julian Le Grand offers an account of public policy that arranges views along two axes: a motivational axis, along which individuals can be knights or knaves, and an agency axis, along which they can be pawns or queens. Knaves are concerned to further their self-interest, understood broadly in terms of whatever people may care about. Following Hume, Le Grand calls such characters “knaves,” but this has no automatic connotations with illegal activities. Knights, on the other hand, are motivated to help others for no private reward, even to the detriment of their interests. Pawns, like the pieces on the chess board, are passive victims of circumstances, unable to make responsible choices. Queens do make such choices: they are empowered agents responsible for their fates.
Cilnidipine, a slow‐acting Ca2+channel blocker, induces relaxation in porcine coronary artery: role of endothelial nitric oxide and [Ca2+]i
Authors: Leung Hok Sum , Yao Xiaoqiang , Leung Fung Ping , Ko Wing Hung , Chen Zhen‐Yu , Gollasch Maik , Huang Yu 
Published: November 2005

Cilnidipine is a dual blocker of L‐type voltage‐gated Ca2+channels in vascular smooth muscle and N‐type Ca2+channels in sympathetic nerve terminals that supply blood vessels. However, the clinical benefits of cilnidipine and underlying mechanisms are incompletely understood. This study was designed to compare the time course of relaxant responses to cilnidipine and nifedipine, and to examine the role of endothelial NO and [Ca2+]iin the vasorelaxation.Porcine left circumflex coronary arteries were isolated and isometric tension was measured with Grass force transducers. Endothelial [Ca2+]iin intact arteries was determined by a calcium fluorescence imaging technique. The free radical scavenging capacity was also assayed.Cilnidipine and nifedipine induced concentration‐dependent relaxations in high KCl‐precontracted artery rings, while the former‐induced relaxation was slower as compared to the latter. Treatment withL‐NAME or ODQ reduced relaxations to cilnidipine or nifedipine to the same extent as in rings without endothelium. Indomethacin orω‐conotoxin had no effects.L‐Arginine antagonized the effect ofL‐NAME on cilnidipine‐induced relaxations. Cilnidipine did not affect sodium nitroprusside‐induced relaxation in rings with and without endothelium.Cilnidipine and nifedipine caused extracellular Ca2+‐dependent increases in endothelial [Ca2+]iin intact arteries and cilnidipine's action had a slower onset, similar to that of cilnidipine‐induced relaxation.Neither cilnidipine nor nifedipine exhibited a free radical scavenging property.The present results demonstrate that cilnidipine can produce endothelium‐dependent relaxation in porcine coronary arteriesin vitroin addition to blocking Ca2+channels. Like short‐acting nifedipine, cilnidipine‐dependent relaxation, albeit to a slower onset, is partly mediated by endothelial NO but not by prostacyclin. The increased release or bioavailability of NO may causally result from elevated endothelial [Ca2+]iin arteries. The Ca2+channel‐independent effect suggests the usefulness of cilnidipine in the treatment of cardiovascular diseases associated with diminished NO release, such as atherosclerosis.British Journal of Pharmacology(2006)147, 55–63. doi:10.1038/sj.bjp.0706450