bluuebunny/crossref_metadata_2025_split huggingface dataset:
Terminal fall velocity and the FASTEX cyclones
Authors: Protat A. , Lemaîitre Y. , Bouniol D. 
Published: April 2003

AbstractKnowledge of water‐drop and ice‐crystal terminal velocities is particularly important for an adequate representation of particle sedimentation in cloud‐resolving and large‐scale models. In this paper, a new method is proposed to retrieve terminal fall velocity from airborne‐Doppler‐radar observations. To extract the terminal fall velocity from the Doppler information, which mixes the three wind components and the terminal fall velocity, statistical considerations are introduced, stating that for a long sampling time span (a whole aircraft mission, for instance) and for moderate storms such as stratiform precipitation, the mean vertical air motions should vanish with respect to the mean terminal fall velocity. Statistical power‐law relationships between terminal fall speed and radar reflectivity are then developed, as well as profiles of mean terminal fall velocity. This underlying hypothesis of the method is validated with in situ measurements of the vertical wind component, averages of convective‐scale retrievals of the vertical wind component, and terminal fall speed–radar reflectivity (VT–Z) relationships derived from in situ measurements of the drop size distribution. These comparisons all indicate that the vertical air motion can indeed be neglected with respect to the terminal fall speed.A detailed analysis of the statistical relationships obtained in liquid and ice phases for six frontal cyclones at different stages of development shows that a ‘universal’ VT–Z rain relationship can be proposed for North Atlantic frontal cyclones at mature stage. This result and further arguments developed in the paper suggest that the drop size distributions are ‘equilibrium’ distributions. In the ice phase, such a ‘universal’ relationship is not found. It is nevertheless suggested in this study that such a general relationship might be derived if the frontal cyclones are split into categories depending on their stage of development. These VT–Z ‘universal’ relationships can be introduced in large‐scale model parametrization schemes in order to better describe the sedimentation of ice and water and dynamical–microphysical interactions occurring within North Atlantic frontal cyclones.Finally, a procedure is proposed to estimate the most representative type of ice particle from 2D‐P in situ sensor and airborne‐Doppler‐radar measurements. It consists of calculating the mean flight‐level Z and the VT–Z relationships in the ice phase for several theoretical ice habits, and to identify the ice habit that reasonably reproduces both the radar‐derived mean flight‐level Z and VT–Z ice relationship. Copyright © 2003 Royal Meteorological Society
The influence of health care organisations on health system performance
Authors: Hauck Katharina , Rice Nigel , Smith Peter 
Published: April 2003

Objectives: The governments of many countries are undertaking initiatives to assess the extent to which health care organisations fulfil important objectives of health care, such as health improvement, fair access and efficiency. However, the extent to which these health care organisations can influence these objectives is unclear. The purpose of this study is to examine the potential influence of English National Health Service territorial health authorities on 14 indicators of system performance. Methods: The study uses performance data relating to approximately 5000 small geographical areas with average populations of 10 000. Multi-level statistical models are used to attribute variation in the indicators to three hierarchical levels - small areas, district health authorities and regional health authorities - after controlling for socio-demographic characteristics. Variations in indicators attributable to district or regional level give an indication of the extent to which health authorities may influence performance. Results: After adjusting for socio-demographic characteristics, the proportion of variation in performance attributable to district health authorities varies from about 8% (for standardised mortality ratios) to about 76% (for waiting time for elective surgery). Variation at the regional level is smaller than at the district level. Conclusions: There appear to be very large variations between indicators in the extent to which health care organisations can influence health system performance. Choice of performance indicators and the managerial incentive regime based on the indicators should recognise this variability, as it is highly dysfunctional to hold managers accountable for measures of performance that are beyond their control.
Does organisational culture influence health care performance? A review of the evidence
Authors: Scott Tim , Mannion Russell , Marshall Martin , Davies Huw 
Published: April 2003

Objective: To review the evidence for a relationship between organisational culture and health care performance. Methods: Qualitative comprehensive review: all empirical studies exploring a relationship between organisational culture (broadly defined) and health care performance (broadly defined) were identified by a comprehensive search of the literature. Study methods and results were analysed qualitatively to provide a narrative review with integrative discussion. Results: Ten studies met the inclusion criteria. There was considerable variation in the design, study setting, quality of reporting and aspects of culture/performance considered. Four of the ten studies reviewed in detail claimed to have uncovered supportive evidence for the hypothesis that culture and performance are linked. All the other studies failed to find a link, though none provided strong evidence against the hypothesis. Conclusions: There is some evidence to suggest that organisational culture may be a relevant factor in health care performance, yet articulating the nature of that relationship proves difficult. Simple relationships such as 'strong culture leads to good performance' are not supported by this review. Instead, the evidence suggests a more contingent relationship, in that those aspects of performance valued within different cultures may be enhanced within organisations that exhibit those cultural traits. A striking finding is the difficulty in defining and operationalising both 'culture' and 'performance' as variables that are conceptually and practically distinct. Considerably greater methodological ingenuity will be required to unravel the relationship(s) between organisational culture(s) and performance(s). Current policy prescriptions, which seek service improvements through cultural transformation, are in need of a more secure evidential base.
Polymer precursor to diamondlike carbon prepared by the polymerization of α,α,α‐trichlorotoluene and acetonitrile
Authors: Ma Mingming , Shi Gaoquan , Xi Chanjuan 
Published: April 2003

AbstractA novel liquid/solid two‐phase reaction of α,α,α‐trichlorotoluene (PhCCl3) and acetonitrile (AN) has been discovered that produces a carbon‐based polymer with diamondlike structure at the atomic level. The solid phase is potassium hydroxide particles, and the liquid phase is a tetrahydrofuran solution of PhCCl3 and AN containing a certain amount of tetrabutylammonium bromide as a phase‐transfer catalyst. The structure of the carbon‐based polymer has been characterized by elemental analysis, Fourier transform infrared spectroscopy, and 1H‐ and 13C‐NMR spectroscopy. The pyrolysis of the carbon‐based polymer at 800°C under a nitrogen atmosphere leads to the formation of a diamondlike carbonaceous material according to the results of X‐ray photoelectron spectroscopy and Raman spectroscopy. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 16–23, 2003
The polycondensation of lithium 11–bromoundecanoate in aqueous media
Authors: Shigetomi Yasumasa , Kojima Takehiro 
Published: April 2003

AbstractTo obtain a biodegradable plastic, polycondensation, the substitution of bromine by carboxylate was carried out on lithium 11–bromoundecanoate. Using water as a solvent, the formation of a double bond was detected between 70 and 100°C, yielding a good quantity of polymer. Water is recommended as the best solvent for the reaction. Thermodynamic investigations were carried out by using ethylene glycol and water. The reaction is believed to proceed according to the SN2 mechanism. The ΔH and ΔG values for condensation in ethylene glycol were slightly higher than for those in water, but the reaction rate in water at 70°C was 7 times greater than that in ethylene glycol. The enhancement of dissociation accounts for the advantageous condensation in aqueous media. Furthermore, ΔS shows negative values and ΔG shows positive values, meaning that the reaction should proceed exothermically and not spontaneously. Experiments to condense 11–bromoundecanoate in aqueous media were carried out for ten days in a water bath, kept at 70°C, using 25 mL of 0.05M 11–bromoundecanoate. The degree of polymerization for the resulting polymer was found to be 23 by the end group assay for both bromine and carboxylate. Neither a melting point nor glass transition point for the product were observed. The polymer formed decomposes at 300°C and instantly disperses. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 130–134, 2003
Morphology of rubber‐modified vinyl ester resins cured at different temperatures
Authors: Auad María L. , Borrajo Julio , Aranguren Mirta I. 
Published: April 2003

AbstractThe morphologies of styrene (St) crosslinked divinylester resins (DVER) modified with elastomers were analyzed. The primary focus of this study was on the effect of the molecular weight of the resins, the reactivity of the elastomeric modifiers, and the temperature of curing. All of these variables have a strong influence on both the miscibility and the viscosity of the system, affecting the phase‐separation process that takes place in the unreacted and the reacting mixture. The selected liquid rubbers were carboxyl‐terminated poly(butadiene‐co‐acrylonitrile) (CTBN), a common toughening agent for epoxy resins, and an almost unreactive rubber with the DVER; and St comonomers and vinyl‐terminated poly(butadiene‐co‐acrylonitrile (VTBN), a reactive rubber. Different morphologies potentially appear in these systems: structures formed by DVER–St nodules surrounded by elastomer and spanning the whole sample; dual cocontinuous micron‐size domains formed by elastomer‐rich or resin‐rich domains; and a continuous DVER–St‐rich phase with included complex nodular domains. These microstructures can be varied by just changing the nature and concentration of the elastomer, the molecular weight of the resin, or the curing temperature. The appearance of these morphologies is discussed as a function of the above variables. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 274–283, 2003
IR spectra of cytochrome c denatured with deuterated guanidine hydrochloride show increase in β sheet
Authors: Speare Jonathan O. , Rush Thomas S. 
Published: April 2003

AbstractAttenuated total reflectance Fourier transform IR (ATR‐FTIR) spectra are obtained for horse heart ferricytochrome c in solutions of 0–7M guanidine hydrochloride and deuterated guanidine hydrochloride. Substitutions of deuterium for hydrogen in both the denaturant and protein provide resolvable amide I spectra over a wide range of denaturant concentrations. Deuteration enhances the ability to measure the true protein IR spectrum in the amide I region in which the secondary structure can be deduced, because spectra in D2O are less prone to spectral distortion upon background denaturant subtraction than spectra in H2O. Other investigators studying equilibrium unfolded cytochrome c were limited to guanidine concentrations below 3.0M because of detector saturation. Detector saturation is avoided with the use of ATR‐FTIR spectroscopy, allowing one to obtain protein spectra at high denaturant concentrations. Second derivative spectra of samples show reductions in α helix and increases in β sheet at high denaturant concentrations, contrary to expectations of finding primarily a random coil secondary structure. Using this new technique, the protein was estimated to consist of 51% β sheet and only 15% random coil in the presence of 6.6M deuterated guanidine hydrochloride. © 2003 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 72: 193–204, 2003
Artbildung im Mikrokosmos
Authors: Kronberg Inge 
Published: April 2003

AbstractParasiten wird eine bedeutende Rolle bei der Erhöhung der genetischen Vielfalt ihrer Wirtspopulation zugesprochen, die schließlich im Laufe der Evolution zu der Bildung neuer Arten führen kann. Wegen der langen Generationszeiten und unkalkulierbarer Wechselwirkungen sind solche Effekte im natürlichen Lebensraum kaum messbar. In einem künstlichen Mikrokosmos lassen sich dagegen Umwelt und genetische Variation kontrollieren.
Der große Wurf der frühen Jäger: Nachbau altsteinzeitlicher Speere
Authors: Rieder Hermann 
Published: April 2003

AbstractDie sensationellen Speerfunde aus Schöningen werden in Bauart und Leistungsfähigkeit experimentell untersucht. Der Homo heidelbergensis vor 400.000 Jahren war zur Gruppenjagd auf Großwild fähig. Dabei halfen ihm Speere, die sowohl von der Wurfweite, als auch von der Zielsicherheit und der Eindringtiefe her den heutigen Speeren ebenbürtig sind. Es zeichnet sich eine Kulturgeschichte des Werfens ab mit den Kapiteln Jagd, Krieg und Sport.
Plateau's problem for parametric double integrals: I. Existence and regularity in the interior
Authors: Hildebrandt Stefan , von der Mosel Heiko 
Published: April 2003

AbstractWe study Plateau's problem for two‐dimensional parametric integrals

the Lagrangian F(x, z) of which is positive definite and at least semi‐elliptic. It turns out that there always exists a conformally para‐me‐trized minimizer. Any such minimizer X is seen to be Hölder‐continuous in the parameter domain B and continuous up to its boundary. If F possesses a perfect dominance function G of class C2, we can establish higher regularity of X in the interior. In fact, we prove X ⊆ Hloc2,2(B, ℝn) ∩ C1,σ(B, ℝn) for some σ > 0. Finally, we discuss the existence of perfect dominance functions.
Laparoscopic radiofrequency ablation of the liver in proximity to major vasculature: Effect of the Pringle maneuver
Authors: Shen Perry , Fleming Shawn , Westcott Carl , Challa Venkat 
Published: April 2003

AbstractBackground and ObjectivesThe Pringle maneuver has been shown to increase ablation size during radiofrequency ablation (RFA). Efficacy of laparoscopic Pringle in proximity to major vasculature has not been well described. Laparoscopic RFA was performed in proximity to major hepatic vessels to examine effects of the Pringle on ablation size and vascular damage.MethodsLaparoscopic RFA was performed in 10 pigs. Each underwent ablation of a peripheral site, and sites adjacent to the portal and hepatic veins. Ultrasound was used to position the RFA adjacent to vascular structures. US flow characteristics verified occlusion of blood flow. Five pigs underwent laparoscopic RFA with Pringle and five underwent laparoscopic RFA alone. Animals were then sacrificed for gross and microscopic evaluation.ResultsPeripheral, hepatic, and portal vein ablations showed no significant differences in volume between non‐Pringle and Pringle lesions, though the median ablation volume for the peripheral site in the Pringle group was approximately twice that of the non‐Pringle group. Pringle group overall median time to target temperature was significantly shorter (P = 0.047). Histologic examination revealed no evidence of endothelial damage or thermal‐induced intravascular thrombosis of the hepatic or portal veins.ConclusionsLaparoscopic RFA with Pringle in proximity to major vascular structures does not significantly increase ablation size, or cause acute vascular damage. Further studies are necessary to determine the utility of the Pringle in proximity to major intrahepatic blood vessels. J. Surg. Oncol. 2003;83:36–41. © 2003 Wiley‐Liss, Inc.
Contributions of side groups to the water diffusion in cured epoxy resins (2) study on physical aging
Authors: Liu Mojun , Ding Yifu , Wang Minghai , Li Shanjun , Liu Weihua , Wang Bo 
Published: April 2003

AbstractNovolac epoxy resins cured with novolac resin, novolac acetate resin, novolac butyrate resin, and novolac phenylacetate resin named as EP, EPA, EPB, and EPP, respectively, were prepared. Their physical aging behavior at a Tg‐30 °C (30 °C below glass‐transition temperature) was examined by positron annihilation lifetime spectroscopy and differential scanning calorimetry. The ortho‐positronium annihilation lifetime τ3 variation extent of EP is less apparent than that of the other three esterified samples during physical aging. The time dependence of ops intensity I3 agreed with the Kohlrausch‐Williams‐Watts (KWW) equation. The relaxation time (τ0) and nonexponential parameter were calculated. The free volume and enthalpy relaxation rate characterized by the reciprocal of τ0 and ∂ΔH/∂logt, respectively, exhibit the same order—EPP > EPB > EPA > EP. These results suggest that the extend and rate of relaxation are not only related to the frozen free volume produced by quenching but also significantly influenced by segmental mobility of the network that attributed to the side‐group flexibility and their interaction with networks. This work also supports the fact that side‐group flexibility and the free‐volume fraction and distribution act in concert to control the water‐diffusion behavior in epoxy networks. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1135–1142, 2003
Surface polarity of cellulose derivates observed by coumarin 151 and 153 as solvatochromic and fluorochromic probes
Authors: Fischer Kristin , Prause Silvio , Spange Stefan , Cichos Frank , Von Borczyskowski Christian 
Published: April 2003

AbstractSolvent‐dependent ultraviolet–visible (UV–vis) absorption and Stokes shifts including strong hydrogen‐bond‐donating (HBD) solvents such as 2,2,2‐trifluoroethanol and 1,1,1,3,3,3‐hexafluoro‐2‐propanol of two coumarine dyes (Co 151 and Co 153) were analyzed with multiple‐square analyses of linear solvation energy relationships and the Kamlet–Taft solvent parameter set to α (HBD capacity), β (hydrogen‐bond‐accepting capacity), and π* (dipolarity/polarizability). The UV–vis absorption and emission spectra of Co 151 and Co 153 were measured when adsorbed on various polysaccharides such as different cellulose batches, carboxymethylcelluloses with different degrees of substitution, and chitine. As a result of this evaluation, Co 153 is recommended as an alternative UV–vis probe for evaluating the dipolarity/polarizability of cellulose and cellulose derivates. Multiple adsorption of Co 153 on Linters cellulose took place indicating a wide‐surface polarity distribution, which makes the determination of a rigid polarity parameter questionable. Thus, fluorescence measurements of adsorbed Co 153 are suitable to detect inhomogenities on a surface but not for the determination of empirical polarity parameters. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1210–1218, 2003
Realization of the universal‐NOT gate and of the universal quantum cloning
Authors: Sias C. , Sciarrino F. , De Martini F. 
Published: April 2003

AbstractAn arbitrary quantum state cannot be “cloned” perfectly, i.e. reproduced with “fidelity” F = 1 into M > 1 states identical to the original by any conceivable physical device. The main root of this impossibility resides in the linearity of quantum mechanics. A second “quantum impossibility” process, based on the complete positivity character of any quantum operation and conceivably subtly related to the first one, forbids the realization of a universal NOT gate i.e. one that flips exactly any input qubit into an orthogonal one. A detailed investigation of these results, representing the most fundamental difference between classical and quantum information, indeed can reveal the detailed structure of the latter one. We report an experimental demonstration of the process of cloning of N = 1 input qubit into M = 2 output qubits by a quantum‐injected optical parametric amplifier OPA. By the same apparatus the realization of a universal NOT gate is also demonstrated. The two processes will be found to be “universal” and optimal, i.e. the measured fidelity of both processes F < 1 will be found close to the theoretical values.
Single trapped ions interacting with low‐ and high‐finesse optical cavities
Authors: Eschner J. , Raab C. , Mundt A. , Kreuter A. , Becher C. , Schmidt‐Kaler F. , Blatt R. 
Published: April 2003

AbstractThe presence of mirrors modifies both the coherent coupling of an atom to a light mode and its spontaneous emission into the mode [1]. We study such cavity QED effects experimentally with single ions and optical cavities. We focus on two examples which are equally interesting as fundamental systems and for application in quantum information processing. (i) By retroreflecting the fluorescence of a single trapped Ba+ ion with a mirror 25 cm away, we observe inhibition and enhancement of the atom's spontaneous emission. When two ions are trapped, the distant mirror creates super‐ and subradiance. (ii) With a single trapped Ca+ ion we demonstrate coherent coupling of its narrow S1/2 – D5/2 “qubit” transition to a mode of a high‐finesse optical cavity. We also achieve deterministic coupling of the cavity standing wave to the ion's vibrational state by controlling the ion's position with nanometer‐precision and selectively exciting vibrational state‐changing transitions.
Quantum interferometry with intense optical pulses
Authors: Leuchs G. , Silberhorn C. , Glöckl O. , Marquardt C. , Korolkova N. 
Published: April 2003

AbstractFor intense optical pulses the optical Kerr interaction in matter such as an optical fiber is large enough to generate quantum states of light with significant non‐classical properties. On this basis pairs of entangled light pulses have been generated. This entanglement can be used for novel schemes in high precision interferometry and for quantum communication protocols such as quantum dense coding.
About the use of entanglement in the optical implementation of quantum information processing
Authors: Paris M.G.A. , D'Ariano G.M. , Lo Presti P. , Perinotti P. 
Published: April 2003

AbstractWe review some applications of entanglement to improve quantum measurements and communication, with the main focus on the optical implementation of quantum information processing. The evolution of continuos variable entangled states in active optical fibers is also analyzed.