bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation, characterization, and optical properties of nano- and submicron-sized Y2O3:Eu3+ phosphors
Authors: Ye Xinyu , Zhuang Weidong , Hu Yunsheng , He Tao , Huang Xiaowei , Liao Chunfa , Zhong Shengwen , Xu Zhifeng , Nie Huaping , Deng Gengfeng
Published: March 2009

Ultrafine Y2O3:Eu3+ phosphors were prepared by a modified solution combustion method. The as-prepared samples with sizes of 17.6–80 nm (nanophosphors) and 300 nm (submicron phosphors) were characterized by x-ray diffraction, transmission electron microscope, scanning electron microscopy, selected area electron diffraction, and energy dispersive x-ray spectroscopy. The emission spectra of the samples are unchanged in comparison with that of standard material. The excitation spectra show a redshift in the charge-transfer-state band and a blueshift in the host gap band. In relation to commercial sample, the relative luminescence intensities of nano- and submicron phosphors are increased sufficiently to 64.4% and 93.6%, respectively. Higher quenching concentration of the activator Eu3+ ion was observed in the nanophosphor than that in the phosphor synthesized by solid state reaction.
Size effects on heat transport in small systems: Dynamical phase transition from diffusive to ballistic regime
Authors: Vázquez F. , Márkus F.
Published: March 2009

The size effects on heat conduction in small systems are analyzed by using irreversible thermodynamics and Boltzmann equation derived heat transport models. The system’s size dependent group velocity of heat waves and thermal response of the system are studied in the diffusive-ballistic transition of heat transport. A critical range of values for the Knudsen number is found which features a dynamic phase transition between the diffusive and ballistic regimes. The transition system’s sizes range from 10 to 380 μm.
Synthesis and functionality of the storage phosphor BaFBr:Eu2+
Authors: Hesse S. , Zimmermann J. , von Seggern H. , Meng X. , Fasel C. , Riedel R.
Published: March 2009

The present paper relates to a method for synthesizing the photostimulable storage phosphor BaFBr:Eu2+ that features high stimulation characteristics for use in image plates. All previous synthesis routes consist of a multistep process whereas the presented route is a one-step synthesis. Starting compounds are BaCO3, NH4F, and NH4Br, as well as EuF3 where the ammonium compounds are highly volatile at temperatures below 300°C. Their reaction products initiate the decomposition of BaCO3 and form BaFBr. The incorporation of F-centers and europium ions occurs at temperature exceeding 550°C. The individual reaction steps are monitored by simultaneous thermal analysis (thermogravimetry/differential thermal analysis) and the gaseous reaction products are detected by in situ mass spectroscopy. Intermediate and final products are characterized by x-ray diffraction techniques to determine the involved phases. Photoluminescence spectra reveal the typical emission peak of Eu2+ accompanied by a redshifted emission band at 470nm, which was assigned to oxygen incorporated into the BaFBr lattice. The synthesized powders exhibit small grain sizes well suited for the use in image plates.
Efficient and accurate local approximations to coupled-electron pair approaches: An attempt to revive the pair natural orbital method
Authors: Neese Frank , Wennmohs Frank , Hansen Andreas
Published: March 2009

Coupled-electron pair approximations (CEPAs) and coupled-pair functionals (CPFs) have been popular in the 1970s and 1980s and have yielded excellent results for small molecules. Recently, interest in CEPA and CPF methods has been renewed. It has been shown that these methods lead to competitive thermochemical, kinetic, and structural predictions. They greatly surpass second order Møller–Plesset and popular density functional theory based approaches in accuracy and are intermediate in quality between CCSD and CCSD(T) in extended benchmark studies. In this work an efficient production level implementation of the closed shell CEPA and CPF methods is reported that can be applied to medium sized molecules in the range of 50–100 atoms and up to about 2000 basis functions. The internal space is spanned by localized internal orbitals. The external space is greatly compressed through the method of pair natural orbitals (PNOs) that was also introduced by the pioneers of the CEPA approaches. Our implementation also makes extended use of density fitting (or resolution of the identity) techniques in order to speed up the laborious integral transformations. The method is called local pair natural orbital CEPA (LPNO-CEPA) (LPNO-CPF). The implementation is centered around the concepts of electron pairs and matrix operations. Altogether three cutoff parameters are introduced that control the size of the significant pair list, the average number of PNOs per electron pair, and the number of contributing basis functions per PNO. With the conservatively chosen default values of these thresholds, the method recovers about 99.8% of the canonical correlation energy. This translates to absolute deviations from the canonical result of only a few kcal mol−1. Extended numerical test calculations demonstrate that LPNO-CEPA (LPNO-CPF) has essentially the same accuracy as parent CEPA (CPF) methods for thermochemistry, kinetics, weak interactions, and potential energy surfaces but is up to 500 times faster. The method performs best in conjunction with large and flexible basis sets. These results open the way for large-scale chemical applications.
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-vulnerabilities: A unified approach to network robustness
Authors: Criado Regino , Pello Javier , Romance Miguel , Vela-Pérez María
Published: March 2009

We define a new general framework, the family of (ψ,p,q)-vulnerabilities, as a tool that produces many new vulnerability functions that measure the capacity of a network to maintain its functional performance under random damages or malicious attacks. This new framework comprises most of the vulnerability definitions appearing in the literature and allows to calculate some relationships between the different (ψ,p,q)-vulnerabilities in terms of their function ψ or their parameters p, q that improve several known results for the vulnerability functions. Some graphics of simulations are provided in order to show the sharpness of these relationships.
Quantum correction to Landau damping of electron plasma waves
Authors: Zhu Jun , Ji Peiyong , Lu Nan
Published: March 2009

It is often assumed that quantum effects will be significant only in the low temperature and high density plasmas. In this paper this assumption is challenged by considering the quantum contribution to the Landau damping of electron plasma waves in normal temperature and high density plasmas. Starting from the linearized Vlasov equation which contains the Bohm quantum potential, the dispersion relation of electron plasma waves propagating in a quantum plasma is derived. A linear Landau damping rate and equations for this process are also deduced. Result indicates that quantum effects enlarge effective frequency of plasmas, which is attributed to an increase in charge or number density of plasma electrons. As a result, Debye length is reduced, and the Debye screening effect becomes obvious. So the quantum behavior appears screening effect here. Landau damping rate is reduced by quantum effects and the exchange of energy between particles and waves is retarded.
Pulse width controlled resistivity switching at room temperature in Bi0.8Sr0.2MnO3
Authors: Rebello A. , Mahendiran R.
Published: March 2009

We report pulsed as well as direct current/voltage induced electroresistance in Bi0.8Sr0.2MnO3 at room temperature. It is shown that bilevel and multilevel resistivity switching can be induced by a sequence of pulses of varying pulse width at a fixed voltage amplitude. Resistivity increases abruptly (≈55% at 300 K) upon reducing pulse width from 100 to 25 ms for a fixed electric field (E=2 V/cm2) of 200 ms pulse period. The resistivity switching is accompanied by a periodic change in temperature, which alone cannot explain the magnitude of the resistivity change.
Hollow-pyramid based scanning near-field optical microscope coupled to femtosecond pulses: A tool for nonlinear optics at the nanoscale
Authors: Celebrano Michele , Biagioni Paolo , Zavelani-Rossi Margherita , Polli Dario , Labardi Massimiliano , Allegrini Maria , Finazzi Marco , Duò Lamberto , Cerullo Giulio
Published: March 2009

We describe an aperture scanning near-field optical microscope (SNOM) using cantilevered hollow pyramid probes coupled to femtosecond laser pulses. Such probes, with respect to tapered optical fibers, present higher throughput and laser power damage threshold, as well as greater mechanical robustness. In addition, they preserve pulse duration and polarization in the near field. The instrument can operate in two configurations: illumination mode, in which the SNOM probe is used to excite the nonlinear response in the near field, and collection mode, where it collects the nonlinear emission following far-field excitation. We present application examples highlighting the capability of the system to observe the nonlinear optical response of nanostructured metal surfaces (gold projection patterns and gold nanorods) with sub-100-nm spatial resolution.
Visible light photocatalytic properties of polymorphic brookite titania
Authors: Lee Burtrand I. , Kaewgun Sujaree , Kim Wooyul , Choi Wonyong , Lee Jae S. , Kim Eunsun
Published: March 2009

Visible light (VL) active titania was prepared via ambient condition sol process. The particles precipitated from titanium tetrachloride solution followed by lattice dehydroxylation using hot N-methylpyrrolidone (NMP) yielded a mixed crystal phase of brookite titania with anatase as the minor phase. The mixed phase titania exhibited superior photocatalytic activities for an organic dye and hydrogen evolution from an aqueous solution under 14W VL as compared with several other available reference titanias. The superior VL photocatalytic activity may be explained as the effective charge separation by the intercrystalline electron transport from brookite to anatase grains complemented by the strong VL absorption by the nitrogen species in NMP. The probable electron transport mechanism is illustrated.
The hydration of aniline: Analysis of spatial distribution functions
Authors: Plugatyr Andriy , Svishchev Igor M.
Published: March 2009

Molecular dynamics simulations of aniline in aqueous infinitely dilute solution are performed from ambient to supercritical conditions. Spatial hydration structures of aniline are examined along the liquid branch of the liquid-vapor coexistence curve of the simple point charge/extended water model at 298, 373, 473, and 573 K and in the supercritical region at 633, 733, and 833 K with density fixed at 0.3 g/cm3. The coordination and H-bond numbers of aniline are calculated. The self-diffusion coefficient of aniline is also evaluated. At room temperature the solvation shell of aniline is comprised of ∼32 water molecules. At 298 K, the amino group is hydrated by three water molecules with which it forms one strong and two weak (0.6) H bonds acting as an acceptor and donor, respectively. In addition, ∼1.5 water molecules are identified as π-coordinated, forming close to 0.75 H bonds with the aromatic ring of aniline. The features of the hydration shell structure of aniline diminish with temperature and decreasing density. The disappearance of π-coordinated water molecules is noted at around 473 K, whereas the loss of the hydrophobic solvent cage is observed near the critical point of water. At supercritical conditions aniline is hydrated by approximately eight water molecules with the amino group coordinated to roughly two of them, forming less than one H bond in total.
Path integral evaluation of H diffusion on Ni(100) surface based on the quantum instanton approximation
Authors: Wang Wenji , Zhao Yi
Published: March 2009

The diffusion coefficients for hydrogen on Ni(100) surface are calculated by using the quantum instanton approximation, together with path integral Monte Carlo and adaptive umbrella sampling techniques. The model includes 163 atoms in which the motions of the hydrogen and 25 Ni atoms are treated quantum mechanically and the left Ni atoms are considered classically. At high temperature, the predicted diffusion coefficients are in good agreement with experiments. As temperature decreases to 80 K the hydrogen tunneling begins to dominate the diffusive process and the transition temperature is found to be 70 K under which the diffusion coefficient is nearly independent of temperature. The calculations also indicate that the quantum motions of surface atoms hinder the diffusive process compared to the rigid surface and purely classical motions of surface atoms. The underlying mechanisms are extensively investigated.
Solid phase epitaxy of amorphous Ge on Si in N2 atmosphere
Authors: Lieten R. R. , Degroote S. , Leys M. , Posthuma N. E. , Borghs G.
Published: March 2009

We demonstrate a straightforward and economical way to obtain smooth germanium layers of high quality on silicon. Thin amorphous germanium layers deposited by plasma enhanced chemical vapor deposition on Si(111) substrates are transformed into single crystalline and smooth layers by solid phase epitaxy in N2 atmosphere. The crystal orientation of the substrate has a clear influence on the crystal quality. This is most likely due to a different growth mode, namely, layer-by-layer for Si(111) and three-dimensional growth for Si(001). The amorphous germanium layer can roughen during annealing due to mobile atoms on the surface. This can be effectively suppressed by annealing in N2 ambient. Electrical measurements show high charge mobility.
Generation of spin-wave pulse trains by current-controlled magnetic mirrors
Authors: Serga A. A. , Neumann T. , Chumak A. V. , Hillebrands B.
Published: March 2009

The evolution of a packet of long-wavelength, dipole-dominated spin waves trapped between two direct current-carrying wires placed on the surface of a ferrite film is observed by Brillouin light scattering. The wires act as semitransparent mirrors confining the packet. Because the spin-wave energy partially passes through these mirrors, trains of spin-wave packets are generated outside the trap. A numerical model is presented and applied to the case when the current in the wires is dynamically controlled. The dynamic control of the mirror reflectivity provides new functionalities interesting for the field of spin-wave logic like that of a spin-wave memory cell.
Magnetic domain-wall motion by propagating spin waves
Authors: Han Dong-Soo , Kim Sang-Koog , Lee Jun-Young , Hermsdoerfer Sebastian J. , Schultheiss Helmut , Leven Britta , Hillebrands Burkard
Published: March 2009

We found by micromagnetic simulations that the motion of a transverse wall (TW)–type domain wall in magnetic thin-film nanostripes can be manipulated via interaction with spin waves (SWs) propagating through the TW. The velocity of the TW motion can be controlled by changes of the frequency and amplitude of the propagating SWs. Moreover, the TW motion is efficiently driven by specific SW frequencies that coincide with the resonant frequencies of the local modes existing inside the TW structure. The use of propagating SWs, whose frequencies are tuned to those of the intrinsic TW modes, is an alternative approach for controlling TW motion in nanostripes.
Energy dependent saturation width of swift heavy ion shaped embedded Au nanoparticles
Authors: Kluth P. , Giulian R. , Sprouster D. J. , Schnohr C. S. , Byrne A. P. , Cookson D. J. , Ridgway M. C.
Published: March 2009

The transformation of Au nanoparticles (NPs) embedded in SiO2 from spherical to rod-like shapes induced by swift heavy ion irradiation has been studied. Irradiation was performed with A197u ions at energies between 54 and 185 MeV. Transmission electron microscopy and small angle x-ray scattering measurements reveal an energy dependent saturation width of the NP rods as well as a minimum size required for the NPs to elongate. The NP saturation width is correlated with the ion track diameter in the SiO2. NP melting and in-plane strain in the irradiated SiO2 are discussed as potential mechanisms for the observed deformation.
GaN quantum dots as optical transducers for chemical sensors
Authors: Weidemann O. , Kandaswamy P. K. , Monroy E. , Jegert G. , Stutzmann M. , Eickhoff M.
Published: March 2009

Ga N ∕ Al N quantum dots were investigated as optical transducers for field effect chemical sensors. The structures were synthesized by molecular-beam epitaxy and covered by a semitransparent catalytic Pt top contact. Due to the thin (3nm) AlN barriers, the variation of the quantum dot photoluminescence with an external electric field along the [0001] axis is dominated by the tunneling current rather than by the quantum confined Stark effect. An increasing field results in a blueshift of the luminescence and a decreasing intensity. This effect is used to measure the optical response of quantum dot superlattices upon exposure to molecular hydrogen.
Superheterodyne detection of laser generated acoustic waves
Authors: Bramhavar Suraj , Pouet Bruno , Murray Todd W.
Published: March 2009

A superheterodyne approach to the detection of laser generated acoustic waves is presented. An amplitude modulated laser source is used to generate high frequency, narrow bandwidth acoustic waves, and the resulting surface displacement is detected using a stabilized Michelson interferometer. The detection laser used in the interferometer is amplitude modulated at a frequency that is offset from the generation laser modulation frequency by a fixed amount, allowing for the optical down-conversion of the high frequency intensity modulation associated with acoustic wave propagation to a low and fixed intermediate frequency, thereby obviating the need for high frequency detection electronics. Results are presented demonstrating the approach for the detection of bulk and surface acoustic waves at frequencies of up to 1 GHz.
Electric field controlled formation and dissociation of multiwalled carbon nanotube conductive pathways in a polymer melt
Authors: Zhang Cheng , Zhu Jun , Ouyang Mi , Ma Chun-an
Published: March 2009

Electric field controlled formation and dissociation of multiwalled carbon nanotube (MWCNT) conductive pathways in a polycarbonate (PC) melt are investigated by the dynamic percolation measurement. The results show that field-induced MWCNT alignment causes the decrease in the activation energy of conductive pathway formation. The directional or disordered alignment of MWCNTs in the PC melt results in the transition from a conductor to an insulator as the electric field changes from 500 to 1 V/cm. This electric-controllable directional or disordered alignment technology is promising for the fabrication of low-dimensional conductive materials and applications of voltage-switch devices.
Identification of Chaetoviridin E from a Cultured Microfungus, Chaetomium sp. and Structural Reassignment of Chaetoviridins B and D
Authors: Kingsland Sally R. , Barrow Russell A.
Published: March 2009

Chaetoviridins E (1) and B (2) are antibiotic active components isolated from the mycelial extract of an elicited laboratory-cultured coprophilous fungus, Chaetomium sp. obtained from the scat of an emu. The structure of chaetoviridin E was determined to be diastereomeric with the known compound chaetoviridin A, whereas a structure revision of chaetoviridins B and D (10) is proposed, reassigning them to be bicyclic lactol-lactones. The structures of chaetoviridins B and E were determined by detailed spectroscopic analysis, while the revision of chaetoviridin D is through analogy.
Microwave-Assisted Synthesis of Vinyl Esters through Ruthenium-Catalyzed Addition of Carboxylic Acids to Alkynes
Authors: Nicks François , Libert Lionel , Delaude Lionel , Demonceau Albert
Published: March 2009

A rapid and efficient method is described for the selective synthesis of enol esters via the microwave-accelerated addition of carboxylic acids to terminal alkynes. The method employs the readily available [RuCl2(p-cymene)(PPh3)] complex as catalyst without the need of bases, and reactions are complete in 20 min.
Microwave-Assisted Chemistry: a Closer Look at Heating Efficiency
Authors: Hoogenboom Richard , Wilms Tom F. A. , Erdmenger Tina , Schubert Ulrich S.
Published: March 2009

Nowadays, microwave heating has evolved into a common tool for chemists based on its numerous advantages over conventional conductive heating. Surprisingly, the efficiency of microwave-assisted heating is still rather unexplored. In this contribution, we report our investigations concerning the heating efficiency of a variety of solvents including polar and apolar substances. Moreover, the effects of adding salt or passive heating elements on the microwave heating efficiency will be addressed. Finally, the heating efficiency of demineralized water is discussed at different volumes and with different microwave power levels in both monomode and multimode microwave synthesizers, demonstrating maximum average heating efficiencies of 10% for small-scale vessels (5 mL), 20% for medium-scale (50 mL), and 30% for large-scale microwave heating (400 mL).
Comparison of the responses of two Indian mustard (Brassica juncea L.) genotypes to post-flowering soil water deficit with the response of canola (B. napus L.) cv. Monty
Authors: Gunasekera C. P. , French R. J. , Martin L. D. , Siddique K. H. M.
Published: March 2009

The responses to water stress during the post-flowering period of two mustard breeding lines (887.1.6.1 and Muscon) and a commercial canola cv. Monty were tested in the field at Merredin in the low-rainfall Mediterranean-type environment of Western Australia. Three water-stress treatments were imposed using supplemental irrigation and a rain-exclusion shelter. Increasing water stress in the post-flowering period significantly reduced dry matter production and seed yields. Harvest index was slightly increased by mild stress, but reduced back to control levels by severe stress. Pods/plant, seeds/pod, and 1000-seed weight were all reduced by water stress. Dry matter production was higher in mustard than in canola, due to its greater water use and radiation interception. Water-use efficiency (WUE) for dry matter production and radiation-use efficiency (RUE) were higher in mustard than in canola. WUE for dry matter production and RUE were insensitive to the levels of water stress in mustard in this experiment, but declined significantly in canola. The greater water use in mustard and insensitivity of WUE for dry matter production and RUE to water stress were attributed to significantly higher levels of osmotic adjustment in mustard, although osmotic adjustment was also observed in canola.
Despite this, canola seed yield was not significantly lower than the seed yield of the better mustard genotype, although stress caused a significantly greater percentage yield reduction in canola. This is because canola had a higher harvest index, which also meant it had higher WUE than mustard for grain production under mild stress. Mustard’s poorer harvest index was due to more of the dry matter being invested in stem and, in the case of cv. Muscon, to a short reproductive duration and a low proportion of pod weight allocated to seed.
Canola had significantly higher seed oil concentration than mustard, which meant that it produced higher total oil yield despite sometimes producing lower seed yield. However, its oil concentration was reduced more by stress than mustard’s, so under the most severe stress conditions, both mustard genotypes produced higher total oil yield. Mustard has potential as an oil-producing crop in the low-rainfall Mediterranean-type environments of Western Australia, but improved genotypes, greater harvest index, and greater seed yield are required.
Efficacy of metformin supplementation during ovarian stimulation of lean PCOS patients undergoing in vitro fertilization
Authors: KUMBAK BANU , KAHRAMAN SEMRA
Published: March 2009

Objective. To evaluate the effect of metformin addition during ovarian hyperstimulation on cycle parameters and outcome of in vitro fertilization (IVF) treatment in polycystic ovary syndrome (PCOS) patients with a body mass index (BMI) <28 kg/m2. Design. Retrospective review of patients’ records. Setting. Istanbul Memorial Hospital Assisted Reproductive Treatment Unit. Population. A total of 339 non‐obese PCOS patients undergoing IVF were evaluated according to the supplementation of metformin. Methods. Cycle parameters and IVF outcomes of 220 patients given metformin were compared to those of 119 patients treated without metformin. Main outcome measures. Implantation and pregnancy rates. Results. Metformin co‐treatment led to significantly lower peak E2 levels (3,481 pg/ml vs. 4,192 pg/ml; p <0.0001). However, gonadotropin consumption, stimulation duration, numbers of total and mature oocytes retrieved, fertilization rate, and ratio of grade I embryos developed were similar in both groups. In the metformin administered group, significantly higher implantation (25% vs. 18%; p = 0.003) and pregnancy rates (58% vs. 45%; p = 0.04) were achieved. Abortion and moderate–severe ovarian hyperstimulation syndrome rates were found to be similar in both groups. Conclusions. Although metformin use was especially and strongly recommended in obese PCOS cases, its supplementation during IVF in PCOS patients with a BMI <28 kg/m2 was observed to be beneficial and efficacious.
Correlation between Aurora‐A expression and the prognosis of cervical carcinoma patients
Authors: ZHANG WEI , WANG JIAN , LIU SHU‐JUAN , HUA WEI , XIN XIAO‐YAN
Published: March 2009

Objective. Aurora‐A, a novel member of the serine/threonine kinase family, has been reported to be correlated with tumorigenesis. Our aim was to investigate whether Aurora‐A expression correlates with clinicopathologic factors and prognosis of cervical carcinoma patients. Design/setting. Retrospective study. Population. Seventy‐four cervical carcinoma patients, between 1996 and 2002. Methods. Reverse transcription‐polymerase chain reaction and Western blot assays were performed to detect the expression of Aurora‐A gene in cervical carcinoma cells and paired cancerous and corresponding noncancerous tissues from 74 cervical carcinoma patients. The expression of Aurora‐A protein in tissues was also determined by immunohistochemistry. The relationships of Aurora‐A expression with clinical factors and prognosis of patients were evaluated by statistical analysis. Results. The expression of Aurora‐A mRNA and protein was significantly higher in cervical carcinoma cells than in normal cervical epithelial cell (p <0.05). The expression of Aurora‐A mRNA in cancerous tissues was significantly higher than that in corresponding noncancerous tissues (p<0.001). The expression of Aurora‐A protein was also increased in tumor tissues by immunochemistry. Aurora‐A transcript expression was correlated with FIGO stage (p = 0.018), tumor differentiation (p = 0.014), parametrial invasion (p = 0.024), lymphnode or hematogenous metastasis (p = 0.005 or 0.019), but not other clinicopathological factors. Patients with high Aurora‐A expression had a poorer disease‐free survival and overall survival rates than patients with low Aurora‐A expression. Multivariate analysis showed that high Aurora‐A mRNA expression was an independent prognostic factor (risk ratio: 2.88; p = 0.005). Conclusions. Aurora‐A might be used as a prognostic marker for cervical carcinoma patients.
Jordanian obstetricians’ personal preference regarding mode of delivery
Authors: LATAIFEH ISAM , ZAYED FAHEEM , AL‐KURAN OQBA , AL‐MEHAISEN LAMA , KHRIESAT WADAH , KHADER YOUSEF
Published: March 2009

The personal preference of Jordanian obstetricians regarding mode of delivery in uncomplicated pregnancy with singleton cephalic presentation at term was surveyed by an anonymous structured questionnaire distributed at five conferences/scientific meetings on obstetrics and gynecology held in Jordan in 2007. The response rate was 70% (n = 315), and 22 (7%) of the respondents chose elective cesarean section (CS). Respondents <45 years seemed to be more in favor of elective CS than those ≥55 years (14.1% vs. 3.7%). In multivariate analysis, increased age was inversely associated with the odds of choosing elective CS (OR = 0.93, 95% CI: 0.88–0.99, p = 0.024) after adjusting for gender, sector, and duration of practice. The main reasons for preferring abdominal delivery were the fear of long‐term sequel (stress incontinence and anal sphincter damage) and the wish to preserve sexual function (86.4 and 50.0%, respectively). The majority of Jordanian obstetricians and gynecologists preferred vaginal delivery in uncomplicated pregnancy for themselves or their wives.
Composite material stent comprising metallic wire and polylactic acid fibers, and its mechanical strength and retrievability
Authors: Shomura Y. , Tanigawa N. , Tokuda T. , Kariya S. , Kojima H. , Komemushi A. , Sawada S.
Published: March 2009

Background: Although metallic stents are characterized by strong expanse of force, thin walls, and easy stent deployment, their removal from the body is usually difficult or impossible due to the difficulty of unraveling their mesh structure. A stent built of a composite material comprising a metallic wire and a polylactic acid (PLA) fiber, in which the metallic wire component could be unraveled after PLA fiber degradation in the body, should allow easy stent removal.

Purpose: To evaluate the mechanical strength and retrievability of a composite material stent comprising a metallic wire and a PLA fiber.

Material and Methods: We produced a composite material stent comprising a metallic wire and a biodegradable fiber (hybrid stent). As the metallic wire is not cross-linked with itself, but with the PLA fibers only, the hybrid stent can be easily unraveled after PLA fiber degradation. This stent was built with a 0.2-mm stainless-steel wire and a 0.23-mm PLA fiber knitted in the same textile as an Ultraflex stent. For comparison, an identical stent was built using PLA fiber only (PLA stent). The mechanical strength of these stents was tested by the radial expansive force response against circumferential shrinkage stress load. Change in radial force due to PLA fiber degradation was estimated by adding an artificial PLA degeneration process, by immersing each stent in a water bath at 80°C for 48 hours. Retrievability of the hybrid stent after PLA degeneration was examined by hooking and pulling out the residual stainless-steel wire from a silicon tube.

Results: The hybrid stent exhibited a linear response in radial expansive force within the range of 15% diameter reduction. The PLA stent did not exhibit linear response at over 15% diameter reduction. Decrease of radial expansive force after PLA degradation was within 5% of the original force in the hybrid stent, but the PLA stent did not create effective radial expansive force. Hybrid stents, even after PLA degradation, exhibited a linear response in radial expansive force, within the range of 15% diameter reduction. The metallic component of the heat-processed hybrid stent was easily unraveled by pulling out the wire.

Conclusion: The hybrid stent comprising a stainless-steel wire and a PLA fiber appears to provide effective radial expansive force and retrievability.
Involvement of the proximal tibiofibular joint in ankylosing spondylitis
Authors: Hong Hyun Pyo , Chung Hye Won , Choi Byeong-Kyoo , Yoon Young Cheol , Choi Sang Hee
Published: March 2009

Background: Ankylosing spondylitis (AS) may affect peripheral joints, with the shoulder, hip, and knee being well known involved sites. However, involvement of the proximal tibiofibular (PTF) joint has not yet been investigated.

Purpose: To evaluate PTF joint abnormalities in patients with AS.

Material and Methods: From July 1997 to June 2005, 16 patients (15 male, one female; mean age 25 years), who were clinically diagnosed with AS, underwent magnetic resonance imaging (MRI) to evaluate knee pain. All patients also underwent plain radiographs of the knee, lumbar spine, and pelvis. Twenty knee MRIs (bilateral in four patients) and 16 sets of knee, lumbar spine, and pelvic radiographs were retrospectively reviewed in order to evaluate possible AS involvement. The presence of abnormalities suggesting AS involvement were recorded separately in the sacroiliac joints, lumbar spine, hip, and femorotibial and PTF joints. If the PTF joint showed any pathologic findings, the radiologic findings were recorded.

Results: Three of 16 patients (18.7%) had pathologic features of the PTF joint observed by plain radiographs or MRI. One of these three patients showed bilateral involvement of the PTF joints on plain radiographs, while the other two patients showed unilateral involvement on MRI. Subchondral sclerosis, cartilage abnormality, erosion, and abnormal bone marrow signal intensity were identified on MRI. Plain radiographs of two patients revealed subchondral sclerosis and spur formation in the PTF joint. The frequencies of involvement of other joints in the 16 patients were as follows: lumbar spine, n=5 (31%), hip joint, n=1 (6%) (identified by plain radiographs), and femorotibial joints, n=10 (62.5%) (identified by knee MRI).

Conclusion: MR imaging of the PTF joint can depict synovial changes and their effect on joint structures in patients with AS. The MRI findings of AS involving the PTF joints are subchondral sclerosis, cartilage abnormality, erosion, and abnormal bone marrow signal intensity.
Speech On Fire
Authors: Chobanoglu Shahvalad , Axundov Yusif
Published: March 2009

Shahvalad Chobanoglu reports on the brutal tactics used to silence the press in Azerbaijan and calls for international action
I Know It When I See It
Authors: Fordyce Tom
Published: March 2009

A timeline of legislation and notable cases
Orthographic Facilitation in Oral Vocabulary Acquisition
Authors: Ricketts Jessie , Bishop Dorothy V. M. , Nation Kate
Published: March 2009

An experiment investigated whether exposure to orthography facilitates oral vocabulary learning. A total of 58 typically developing children aged 8–9 years were taught 12 nonwords. Children were trained to associate novel phonological forms with pictures of novel objects. Pictures were used as referents to represent novel word meanings. For half of the nonwords children were additionally exposed to orthography, although they were not alerted to its presence, nor were they instructed to use it. After this training phase a nonword–picture matching posttest was used to assess learning of nonword meaning, and a spelling posttest was used to assess learning of nonword orthography. Children showed robust learning for novel spelling patterns after incidental exposure to orthography. Further, we observed stronger learning for nonword–referent pairings trained with orthography. The degree of orthographic facilitation observed in posttests was related to children's reading levels, with more advanced readers showing more benefit from the presence of orthography.
Success of an Infection Control Program to Reduce the Spread of Carbapenem-Resistant Klebsiella pneumoniae
Authors: Kochar Sandeep , Sheard Timothy , Sharma Roopali , Hui Alan , Tolentino Elaine , Allen George , Landman David , Bratu Simona , Augenbraun Michael , Quale John
Published: March 2009

Objective.

To assess the effect of enhanced infection control measures with screening for gastrointestinal colonization on limiting the spread of carbapenem-resistant Klebsiella pneumoniae in a New York City hospital endemic for this pathogen.

Design.

Retrospective observational study with pre- and postinterventional phases.

Methods.

Beginning in 2006, a comprehensive infection control program was instituted in a 10-bed medical and surgical intensive care unit at a university-based medical center. In addition to being placed in contact isolation, all patients colonized or infected with carbapenem-resistant gram-negative bacilli, vancomycin-resistant Enterococcus, or methicillin-resistant Staphylococcus aureus were cohorted to one end of the unit. Improved decontamination of hands and environmental surfaces was encouraged. In addition, routine rectal surveillance cultures were screened for the presence of carbapenem-resistant pathogens. The number of patients per quarter with clinical cultures positive for carbapenem-resistant K. pneumoniae was compared during the approximately 2-year periods before and after the intervention.

Results.

The mean number ( ± SD) of new patients per 1,000 patient-days per quarter with cultures yielding carbapenem-resistant K. pneumoniae decreased from 9.7 ± 2.2 before the intervention to 3.7 ± 1.6 after the intervention (P< .001 ). There was no change in the mean number of patient-days or the mean number of patients per quarter with cultures yielding methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, or carbapenem-resistant Acinetobacter baumannii or Pseudomonas aeruginosa after the intervention. There was no association between antibiotic usage patterns and carbapenem-resistant K. pneumoniae.

Conclusions.

The comprehensive intervention that combined intensified infection control measures with routine rectal surveillance cultures was helpful in reducing the incidence of carbapenem-resistant K. pneumoniae in an intensive care unit where strains producing the carbapenemase KPC were endemic.
Community diversity reduces
Schistosoma mansoni
transmission, host pathology and human infection risk
Authors: Johnson Pieter T.J , Lund Peder J , Hartson Richard B , Yoshino Timothy P
Published: March 2009

Global biodiversity loss and disease emergence are two of the most challenging issues confronting science and society. Recently, observed linkages between species-loss and vector-borne infections suggest that biodiversity may help reduce pathogenic infections in humans and wildlife, but the mechanisms underlying this relationship and its applicability to a broader range of pathogens have remained speculative. Here, we experimentally evaluated the effects of host community structure on transmission of the human pathogen,
Schistosoma mansoni
, which alternates between snail intermediate hosts and vertebrate definitive hosts. By manipulating parasite exposure and community diversity, we show that heterospecific communities cause a 25–50 per cent reduction in infection among snail hosts (
Biomphalaria glabrata
). Infected snails raised alongside non-host snails (
Lymnaea
or
Helisoma
sp.) also produced 60–80 per cent fewer cercariae, suggesting that diverse communities could reduce human infection risk. Because focal host density was held constant during experiments, decreases in transmission resulted entirely from diversity-mediated pathways. Finally, the decrease in infection in mixed-species communities led to an increase in reproductive output by hosts, representing a novel example of parasite-mediated facilitation. Our results underscore the significance of community structure on transmission of complex life-cycle pathogens, and we emphasize enhanced integration between ecological and parasitological research on the diversity–disease relationship.
Female offspring desertion and male-only care increase with natural and experimental increase in food abundance
Authors: Eldegard Katrine , Sonerud Geir A
Published: March 2009

In species with biparental care, one parent may escape the costs of parental care by deserting and leaving the partner to care for the offspring alone. A number of theoretical papers have suggested a link between uniparental offspring desertion and ecological factors, but empirical evidence is scarce. We investigated the relationship between uniparental desertion and food abundance in a natural population of Tengmalm's owl
Aegolius funereus
, both by means of a 5-year observational study and a 1-year experimental study. Parents and offspring were fitted with radio-transmitters in order to reveal the parental care strategy (i.e. care or desert) of individual parents, and to keep track of the broods post-fledging. We found that 70 per cent of the females from non-experimental nests deserted, while their partner continued to care for their joint offspring alone. Desertion rate was positively related to natural prey population densities and body reserves of the male partner. In response to food supplementation, a larger proportion of the females deserted, and females deserted the offspring at an earlier age. Offspring survival during the post-fledging period tended to be lower in deserted than in non-deserted broods. We argue that the most important benefit of deserting may be remating (sequential polyandry).
The apolipoprotein L family of programmed cell death and immunity genes rapidly evolved in primates at discrete sites of host–pathogen interactions
Authors: Smith Eric E. , Malik Harmit S.
Published: March 2009

Apolipoprotein L1 (APOL1) is a human protein that confers immunity toTrypanosoma bruceiinfections but can be countered by a trypanosome-encoded antagonist SRA.APOL1belongs to a family of programmed cell death genes whose proteins can initiate host apoptosis or autophagic death. We report here that all six members of theAPOLgene family (APOL1-6) present in humans have rapidly evolved in simian primates.APOL6, furthermore, shows evidence of an adaptive sweep during recent human evolution. In eachAPOLgene tested, we found rapidly evolving codons in or adjacent to the SRA-interacting protein domain (SID), which is the domain of APOL1 that interacts with SRA. InAPOL6, we also found a rapidly changing 13-amino-acid cluster in the membrane-addressing domain (MAD), which putatively functions as a pH sensor and regulator of cell death. We predict thatAPOLgenes are antagonized by pathogens by at least two distinct mechanisms: SID antagonists, which include SRA, that interact with the SID of various APOL proteins, and MAD antagonists that interact with the MAD hinge base of APOL6. These antagonists either block or prematurely cause APOL-mediated programmed cell death of host cells to benefit the infecting pathogen. These putative interactions must occur inside host cells, in contrast to secreted APOL1 that trafficks to the trypanosome lysosome. Hence, the dynamicAPOLgene family appears to be an important link between programmed cell death of host cells and immunity to pathogens.
THIS ARTICLE HAS BEEN RETRACTED Epstein–Barr virus‐encoded latent membrane protein 1 activates β‐catenin signaling in B lymphocytes
Authors: Tomita Mariko , Dewan Md. Zahidunnabi , Yamamoto Naoki , Kikuchi Akira , Mori Naoki
Published: March 2009

The Epstein–Barr virus‐encoded latent membrane protein 1 is considered the Epstein–Barr virus oncogene based on its importance in Epstein–Barr virus‐induced B‐lymphocyte transformation. β‐Catenin is a potential oncogene, and its accumulation has been implicated in a variety of human cancers. Here, we found that β‐catenin protein was highly expressed in Epstein–Barr virus‐immortalized B‐cell lines compared with peripheral blood mononuclear cells from healthy donors. β‐Catenin expression in Epstein–Barr virus‐immortalized B‐cell line decreased following treatment with LY294002, an inhibitor of phosphatidylinositol 3‐kinase. Treatment with LY294002 or knockdown of β‐catenin by small interfering RNA reduced the growth of Epstein–Barr virus‐immortalized B‐cell line. Transient transfection of latent membrane protein 1 expression plasmid increased β‐catenin protein expression and β‐catenin‐dependent transcription. Latent membrane protein 1 deletions mutants lacking the carboxyl‐terminal activating region 1 domain failed to enhance β‐catenin protein expression and β‐catenin‐dependent transcriptional activity. They also failed to increase phosphorylated AKT expression. Dominant‐negative AKT suppressed latent membrane protein 1‐induced β‐catenin‐dependent transcriptional activity. These results suggest that latent membrane protein 1 activates β‐catenin through the phosphatidylinositol 3‐kinase/AKT signaling pathway. Activation of the β‐catenin pathway by Epstein–Barr virus may contribute to the lymphoproliferation characteristic of Epstein–Barr virus‐infected B‐cells. (Cancer Sci 2009; 100: 807–812)
Traditional kinship foster care in northern Ghana: the experiences and views of children, carers and adults in Tamale
Authors: Kuyini Ahmed Bawa , Alhassan Abdul Razak , Tollerud Inga , Weld Hanne , Haruna Iddi
Published: March 2009

Surveys were employed to explore the experiences of children in care and their carers about traditional fostering. They also examined the perspectives of randomly selected adults in the community about the practice of traditional foster care in the Tamale area of northern Ghana. The 74 participants responded to closed‐ and open‐ended interview questions about traditional foster care. Frequencies and thematic grouping of qualitative responses showed that the need to keep family ties alive was the key reason for placement of children with family and kin. Majority of the children expressed satisfaction with living in foster care, even though they had experienced physical and emotional abuse and intimidation. Although most carers were not formally employed and had little personal income, they were positive about having the care role, but faced challenges in providing for many children in a difficult economic situation. The report highlights the role of reciprocity, altruistic and socio‐cultural factors in quality of care, and the potential for the traditional kinship foster care to provide suitable avenues of placement for children as recommended by the Ghana child rights law. It also identifies the need for education for carers around children's needs and Ghana's child rights law.
A longitudinal study of autism spectrum disorders in individuals diagnosed with a developmental language disorder as children
Authors: Mouridsen S. E. , Hauschild K‐M.
Published: March 2009

Background  A number of studies have shown that the diagnosis of developmental language disorder (DLD) can be unstable over time, such that young children with a diagnosis of DLD may show symptoms more characteristics of autism spectrum disorder (ASD) at a later date.

Method  To estimate the types and prevalence of ASD 469 individuals with a DLD, consecutively assessed in the same clinic during a period of 10 years, and 2345 controls from the general population were screened for ASD through the nationwide Danish Psychiatric Central Register (DPCR). The mean length of observation was 34.7 years, and the mean age at follow‐up 35.8 (range: 28.3–46.7) years.

Results  At follow‐up, 10 (2.1%) in the DLD group and two (0.09%) in the comparison group were known in the DPCR with a diagnosis of any ASD (P < 0.0001; odds ratio = 25.5; 95% confidence interval 5.5–116.9).

Conclusion  Our results provide additional support to the notion that DLD is a marker of increased vulnerability to the development of ASD.