bluuebunny/crossref_metadata_2025 huggingface dataset:
Seeding method with silicon powder for the formation of silicon spheres in the drop method
Authors: Liu Zhengxin , Nagai Takehiko , Masuda Atsushi , Kondo Michio , Sakai Kazutoshi , Asai Koichi
Published: May 2007

Silicon spheres with a size distribution around 1.0 mm diameter, which are applicable to spherical solar cells, were formed by dropping molten silicon through a nozzle in a free-fall tube, namely, the drop method. Here we show a seeding technique for the formation of silicon spheres. In this technique, pure silicon powders with a size distribution of 1−75 μm were ejected to the molten silicon droplets at a selected part of the free-fall tube using argon carrier gas. It was considered that the attached silicon powders on the droplets worked as nuclei and stimulated the solidification to occur at low undercooling from one place. Characterizations with scanning electron microscope, carrier lifetime, and photoluminescence measurements demonstrated that the crystallinity of silicon spheres were significant improved by the seeding method. The undercooling of molten silicon droplets at solidification was speculated to decrease from ∼250 °C to below 50 °C by seeding power ejection. This resulted in an increase of average minority carrier lifetime from <0.1 μs  to >1.0 μs.
Fano-Rashba effect in a double quantum dot Aharonov-Bohm interferometer
Authors: Chi Feng , Liu Jin-Long , Sun Lian-Liang
Published: May 2007

The interplay between the Fano and Rashba spin-orbit (RSO) effects in an Aharonov-Bohm (AB) interferometer containing two noninteracting quantum dots (QDs) in each of its arms is studied by employing the Green’s function equation of motion. When electrons flow through the upper and lower arms of the interferometer, the RSO interaction in the QDs induces a spin-dependent phase factor in the linewidth matrix elements. By the co-action of this phase factor and the magnetic flux penetrating the AB ring, an interesting spin-dependent Fano effect will arise. It is found that the Fano line shapes of the two spin components in the conductance spectra can be tuned either synchronously or individually with the help of the structure parameters relevant to the RSO coupling strength, magnetic flux, and the structure configuration. We focus our attention on the manipulation of the swap operation of the resonances centered at the bonding and antibonding energies, spin-flip processes, and the broadening of the resonances, which might have practical applications in spintronics devices. We also find that both the broadening of the resonances and the spin polarization efficiency can be controlled in terms of the dot-lead coupling strength.
Anisotropic nonadditive ab initio force field for noncovalent interactions of H2
Authors: Donchev A. G. , Galkin N. G. , Tarasov V. I.
Published: May 2007

A quantum mechanical polarizable force field (QMPFF) has been applied to the noncovalent interactions of molecular hydrogen as well as closed-shell monoatomic species (CSMS): rare gases, alkali cations, and halide anions. The importance of all the main energy components is demonstrated: electrostatics (including penetration effect), exchange repulsion, dispersion, and induction. As the MP2 level of quantum mechanics, which is used to parametrize QMPFF, significantly underestimates the H2–H2 dimer binding energy, the force field was refined using state-of-the-art CCSD(T) data. The approach demonstrates excellent transferability, which is confirmed by accurate reproduction of mixed H2-CSMS dimers and the second virial coefficient of hydrogen vapor.
High-speed picosecond pulse response GaNAsSb p-i-n photodetectors grown by rf plasma-assisted nitrogen molecular beam epitaxy
Authors: Tan K. H. , Yoon S. F. , Loke W. K. , Wicaksono S. , Lew K. L. , Stöhr A. , Ecin O. , Poloczek A. , Malcoci A. , Jäger D.
Published: May 2007

The authors report on picosecond pulse response GaNAsSb∕GaAs p-i-n photodetectors grown by molecular beam epitaxy in conjunction with a rf plasma-assisted nitrogen source. The 2μm thick GaNAsSb photoabsorption layer contains 3.3% of N and 8% of Sb resulting in a dc photoresponse up to 1380nm wavelength. Dark current densities at 0 and −5V are 1.6×10−5 and 13A∕cm2, respectively. The GaNAsSb photodiodes exhibit a record pulse response width of only 40.5ps (full width at half maximum) corresponding to a 4.5GHz bandwidth.
Microscopic origin of the humidity dependence of the adhesion force in atomic force microscopy
Authors: Jang Joonkyung , Yang Mino , Schatz George
Published: May 2007

Water condenses between an atomic force microscope (AFM) tip and a surface to form a nanoscale bridge that produces a significant adhesion force on the tip. As humidity increases, the water bridge always becomes wider but the adhesion force sometimes decreases. The authors show that the humidity dependence of the adhesion force is intimately related to the structural properties of the underlying water bridge. A wide bridge whose width does not vary much with tip-surface distance can increase its volume as distance is increased. In this case, the adhesion force decreases as humidity rises. Narrow bridges whose width decreases rapidly with increasing tip-surface distance give the opposite result. This connection between humidity dependence of the adhesion force and the structural susceptibility of the water bridge is illustrated by performing Monte Carlo simulations for AFM tips with various hydrophilicities.
365
nm
operation of n-nanowire/p-gallium nitride homojunction light emitting diodes
Authors: Motayed Abhishek , Davydov Albert V. , He Maoqi , Mohammad S. N. , Melngailis John
Published: May 2007

The authors report gallium nitride (GaN) nanoscale light emitting diodes utilizing n-GaN nanowire/p-GaN substrate homojunctions. Utilizing electric field assisted alignment, n-type gallium nitride nanowires were placed on the surface of a p-doped GaN thin film. Electroluminescence with 365nm peak wavelength and 25nm full width half maximum was observed from these p-n junctions. These nanowire/epilayer p-n junction diodes were passivated with a thin layer of SiO2 and did not exhibit any parasitic emission related to the bulk or surface defects. The present fabrication scheme, utilizing only batch fabrication techniques, yields reliable, electrically injected nanoscale ultraviolet light sources.
Optical characteristics of a-plane InGaN∕GaN multiple quantum wells with different well widths
Authors: Ko T. S. , Lu T. C. , Wang T. C. , Lo M. H. , Chen J. R. , Gao R. C. , Kuo H. C. , Wang S. C. , Shen J. L.
Published: May 2007

a -plane InGaN∕GaN multiple quantum wells of different widths ranging from 3to12nm were grown on r-plane sapphire by metal organic chemical vapor deposition for investigation. The peak emission intensity of the photoluminescence (PL) reveals a decreasing trend as the well width increases from 3to12nm. Low temperature (9K) time-resolved PL study shows that the sample with 3-nm-thick wells has a better optical property with a fast exciton decay time of 0.57ns. The results of cathodoluminescence and micro-PL scanning images for samples of different well widths further verify the more uniform and stronger luminescence intensity distribution observed for the samples of thinner quantum wells, indicating that the important growth parameters for a-plane InGaN∕GaN multiple quantum wells could be dominated by the In fluctuation and crystal quality during the epitaxial growth.
High-efficiency polymer photovoltaic devices from regioregular-poly(3-hexylthiophene-2,5-diyl) and [6,6]-phenyl-C61-butyric acid methyl ester processed with oleic acid surfactant
Authors: Wang Wenli , Wu HongBin , Yang CuiYing , Luo Chan , Zhang Yong , Chen JunWu , Cao Yong
Published: May 2007

Bulk heterojunction photovoltaic cells, comprised of regioregular-poly(3-hexylthiophene-2,5-diyl) (P3HT) and[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) in the presence of the surfactant, oleic acid (OA), have been studied. The device with OA after thermal annealing has a power conversion efficiency (ηe) of 4.3%, while the devices without OA after thermal annealing have ηe=3.1%. Based on atomic force microscopy, x-ray diffraction investigation found that with OA, the P3HT-PCBM films have better molecular local ordering after thermal annealing resulting in larger donor and acceptor interfaces and higher mobility, thereby higher performance of the photovoltaic cell.
Improvement of charge injection efficiency in organic-inorganic hybrid solar cells by chemical modification of metal oxides with organic molecules
Authors: Kudo Naomi , Honda Satoshi , Shimazaki Yuta , Ohkita Hideo , Ito Shinzaburo , Benten Hiroaki
Published: May 2007

The effect of chemical modification of metal oxide surface with dye molecules in organic-inorganic hybrid solid solar cells was studied by using double layered cells consisting of poly(3-hexylthiophene) (P3HT) and a flat layer of dense TiO2. The external quantum efficiency of the chemically modified cell was nearly double that expected from the photosensitizing effect of the dye molecules. The additional increase shows that the chemical modification with dye molecules can serve not only as a photosensitizer but mainly as an energy funnel and/or an electronic mediator to significantly improve the electron injection efficiency from P3HT to TiO2.
High-mobility double-gate organic single-crystal transistors with organic crystal gate insulators
Authors: Yamagishi M. , Takeya J. , Tominari Y. , Nakazawa Y. , Kuroda T. , Ikehata S. , Uno M. , Nishikawa T. , Kawase T.
Published: May 2007

High-mobility organic transistors are fabricated on both surfaces of approximately 1-μm-thick rubrene crystals, molecularly flat over an area of 10×10μm2. A thin platelet of 9,10-diphenylanthracene single crystal and surface-passivated SiO2 are used for the gate insulators. Because of the minimized densities of hole-trapping levels at the interfaces and in the rubrene crystal, the field-induced carriers do not necessarily reside near the interface but are distributed in the bulk of the semiconductor by adjusting the two gate voltages. Making use of the highly mobile carriers in the inner crystal, the mobility is maximized to ∼43cm2∕Vs.
Phenomenological model for the spontaneous polarization of GaN
Authors: Yan W. S. , Zhang R. , Xiu X. Q. , Xie Z. L. , Han P. , Jiang R. L. , Gu S. L. , Shi Y. , Zheng Y. D.
Published: May 2007

A phenomenological model is presented to determine the experimental value of the spontaneous polarization of GaN. The expression of the spontaneous polarization at room temperature is obtained. The electrostrictive coefficient M33 of a wurtzite GaN film is used to evaluate the experimental value of the spontaneous polarization of GaN. The exact experimental value of the spontaneous polarization of GaN can be obtained as long as the electrostrictive coefficient M33 of the single crystal zinc blende GaN film is measured. The phenomenological model can also be used to determine the experimental values of the spontaneous polarization in other III-V nitrides, AlN and InN.
High-temperature interband cascade lasers emitting at λ=3.6–4.3μm
Authors: Canedy C. L. , Bewley W. W. , Kim M. , Kim C. S. , Nolde J. A. , Larrabee D. C. , Lindle J. R. , Vurgaftman I. , Meyer J. R.
Published: May 2007

The authors report the operating characteristics of ten-stage interband cascade lasers from two wafers with room-temperature wavelengths of 4.1 and 4.3μm. For 150-μm-wide stripes, the threshold current densities are as low as 4.8A∕cm2 at 78K (cw) and 1.15kA∕cm2 at room temperature (pulsed). At 78K, the cw wall-plug efficiency for an 11-μm-wide ridge with 0.5-mm-long cavity and coated facets is 27%, while a 3-mm-long cavity emits a maximum cw power of 200mW. Devices from the two wafers have maximum cw operating temperatures of 261K (λ≈4.0μm) and 243K (λ≈4.2μm).
Analysis of the x-ray refraction using an array-structured detector
Authors: Coan Paola , Bravin Alberto
Published: May 2007

A crystal-less method for analyzing the phase shifts of an x-ray beam passed through a sample is here presented. An array-structured detector is used both to record and analyze the refracted and scattered radiation. Experimental studies of simple phase objects confirmed that images show features similar or equivalent to the ones produced using an analyzer crystal with comparable signal-to-noise ratio values. Using a detector for analyzing the refraction presents evident advantages in terms of optical stability. In addition, with a single acquisition, several refraction angles can be simultaneously analyzed permitting a better exploitation of the dose delivered to the sample.
Epitaxial LaAlO3 thin film on silicon: Structure and electronic properties
Authors: Mi Y. Y. , Yu Z. , Wang S. J. , Lim P. C. , Foo Y. L. , Huan A. C. H. , Ong C. K.
Published: May 2007

Epitaxial LaAlO3 films have been grown on Si (001) by molecular beam epitaxy with an ultrathin SrTiO3 seed layer. High resolution x-ray diffraction and transmission electron microscopy show the high quality epitaxial structure of LaAlO3 films, and the epitaxial relationship of LaAlO3 with Si is LaAlO3(001)‖Si(001) and LaAlO3[100]‖Si[110]. The band gap of epitaxial LaAlO3 films was measured to be 6.5±0.1eV from O 1s loss spectra. Band offsets between crystalline LaAlO3 films and Si were determined to be partitioned equally with 2.86±0.05eV for valence-band offset and 2.52±0.1eV for conduction-band offset by using x-ray photoelectron spectroscopy.
Manipulation of magnetic particles on chip by magnetophoretic actuation and dielectrophoretic levitation
Authors: Liu Chengxun , Lagae Liesbet , Borghs Gustaaf
Published: May 2007

The prospect of using magnetic particles for biomedical purposes in lab-on-a-chip systems compels accurate and flexible particle manipulation. Toward such a goal we designed a microdevice comprising a pair of meander-shaped current carrying conductors, which enable simultaneous magnetophoresis and dielectrophoresis by generating both a traveling magnetic field and an ac electric field. Therefore, both the in-plane and out-of-plane movements of magnetic particles can be electrically controlled. A transport speed of tens of μm∕s was achieved with actuation forces at piconewton scale. The enhanced control of particle movement avoids the contact and nonspecific adhesion between the particle and device.
Optical and electronic properties of GaAs-based structures with columnar quantum dots
Authors: Motyka M. , Sęk G. , Ryczko K. , Andrzejewski J. , Misiewicz J. , Li L. H. , Fiore A. , Patriarche G.
Published: May 2007

The electronic properties of a structure with columnar quantum dots obtained by close stacking of InAs submonolayers have been investigated by contactless electroreflectance (CER) and photoluminescence. These dots have an almost ideally rectangular cross section and uniform composition, which is promising for polarization independent gain. After energy level calculations in the effective mass approximation using composition profiles obtained from cross-sectional transmission electron microscopy the part of the CER spectrum related to the two-dimensional surrounding layer has been explained and single heavy-hole-like and light-hole-like transitions related to the columnar dots identified, due to a single electron state confined in a shallow in-plane potential.
Nonvolatile low-temperature polycrystalline silicon thin-film-transistor memory devices with oxide-nitride-oxide stacks
Authors: Liu Po-Tsun , Huang C. S. , Chen C. W.
Published: May 2007

Nonvolatile memory devices with oxide-nitride-oxide stack structures were fabricated on glass substrates using low-temperature polycrystalline silicon technology. The Fowler-Nordheim tunneling scheme is more suitable than channel hot carrier injection for the programming of the polycrystalline silicon nonvolatile memory device. A memory window of 1.5V can be obtained at a programming voltage of 20V. After 104 programming/erasing cycles, a threshold voltage shift of 1.5V is maintained. Furthermore, the proposed memory device exhibits good retention for 50h at 60°C without a significant decline in the memory window.
Highly (110)- and (111)-oriented BiFeO3 films on BaPbO3 electrode with Ru or Pt∕Ru barrier layers
Authors: Lee Chia-Ching , Wu Jenn-Ming , Hsiung Chang-Po
Published: May 2007

Highly (110)- and (111)-oriented BiFeO3 (BFO) films were fabricated with BaPbO3 (BPO)∕Ru and BPO∕Pt∕Ru as electrode/barrier on Si substrates by rf-magnetron sputtering. The BPO∕Ru and BPO∕Pt∕Ru stacks both induce oriented BFO films and act as diffusion barriers. The (110)- and (111)-oriented BFO films possess excellent ferroelectric properties with only minor leakage. The values of remnant polarization are almost the same, about 42μC∕cm2, for (110)- and (111)-oriented BFO films. However, polarization measured under varying pulse widths demonstrates that the switching polarization in (111)-oriented BFO films is higher than in (110)-oriented films. Additionally, (111)-oriented BFO films exhibit better retention properties than (110)-oriented films.
Atomic force microscope nanolithography of polymethylmethacrylate polymer
Authors: Teixeira F. S. , Mansano R. D. , Salvadori M. C. , Cattani M. , Brown I. G.
Published: May 2007

We describe a nanolithography process for a polymethylmethacrylate (PMMA) surface using scanning contact atomic force microscopy. Parallel furrows were scribed with a pyramidal silicon tip using the same scan mechanism as used to image samples. The PMMA was first electron beam irradiated using a scanning electron microscope and developed. The topography formed is reproducible and predictable. Material from the region where the tip scribes is moved to nearby regions, and aligned, elongated PMMA fragments are seen to decorate the valleys between furrows.
Simultaneous enhancement of toughness, ductility, and strength of nanocrystalline ceramics at high strain-rates
Authors: Mo Yifei , Szlufarska Izabela
Published: May 2007

Molecular dynamics simulations of tensile testing have been performed on nc-SiC. Reduction of grain size promotes simultaneous enhancement of ductility, toughness, and strength. nc-SiC fails by intergranular fracture preceded by atomic level necking. Conventionally, high strain-rate deformations of ceramics are limited by diffusion time scales, since diffusion prevents premature cavitation and failure. The authors report a nondiffusional mechanism for suppressing premature cavitation, which is based on unconstrained plastic flow at grain boundaries. Based on the composite’s rule of mixture, they estimate Young’s modulus of random high-angle grain boundaries in nc-SiC to be about 130GPa.
The Occlusion Illusion: Partial Modal Completion or Apparent Distance?
Authors: Palmer Stephen E , Brooks Joseph L , Lai Kevin S
Published: May 2007

In the occlusion illusion, the visible portion of a partly occluded object (eg a semicircle partly hidden behind a rectangle) appears to be significantly larger than a physically identical region that is fully visible. This illusion may occur either because the visual system ‘fills in’ a thin strip along the occluded border (the partial-modal-completion hypothesis) or because the partly occluded object is perceived as farther away (the apparent-distance hypothesis). We measured the magnitude of the occlusion illusion psychophysically in several experiments to investigate its causes. The results of experiments 1–3 are consistent with the general proposal that the magnitude of the illusion varies with the strength of the evidence for occlusion, supporting the inference that it is due to occlusion. Experiment 4 provides a critical test between apparent-distance and partial-modal-completion explanations by determining whether the increase in apparent size of the occluded region results from a change in its perceived shape (due to the modal extension of the occluded shape along the occluding edge, as predicted by the partial-modal-completion hypothesis) or from a change in its perceived overall size (as predicted by the apparent-distance hypothesis). The results more strongly support the partial-modal-completion hypothesis.
Synthesis of glycerol phosphate lipoteichoic acid in
Staphylococcus aureus
Authors: Gründling Angelika , Schneewind Olaf
Published: May 2007

Lipoteichoic acid (LTA), a glycerol phosphate surface polymer, is a component of the envelope of Gram-positive bacteria. However, the molecular basis for its synthesis or function is not known. Here we report that
Staphylococcus aureus
LtaS synthesizes glycerol phosphate LTA. Construction of a mutant
S. aureus
strain with inducible
ltaS
expression revealed that LTA synthesis is required for bacterial growth and cell division. An
ltaS
homologue of
Bacillus subtilis
restored LTA synthesis and the growth of
ltaS
mutant staphylococci. Thus, LtaS inhibition can be used as a target to treat human infections caused by antibiotic-resistant
S. aureus
or other bacterial pathogens.
Identification of the Photorespiratory 2-Phosphoglycolate Phosphatase, PGLP1, in Arabidopsis
Authors: Schwarte Sandra , Bauwe Hermann
Published: May 2007

The chloroplastidal enzyme 2-phosphoglycolate phosphatase (PGLP), PGLP1, catalyzes the first reaction of the photorespiratory C2 cycle, a major pathway of plant primary metabolism. Thirteen potential PGLP genes are annotated in the Arabidopsis (Arabidopsis thaliana) genome; however, none of these genes has been functionally characterized, and the gene encoding the photorespiratory PGLP is not known. Here, we report on the identification of the PGLP1 gene in a higher plant and provide functional evidence for a second, nonphotorespiratory PGLP, PGLP2. Two candidate genes, At5g36700 (AtPGLP1) and At5g47760 (AtPGLP2), were selected by sequence similarity to known PGLPs from microorganisms. The two encoded proteins were overexpressed in Escherichia coli and both show PGLP activity. T-DNA knockout of one of these genes, At5g36700, results in very low leaf PGLP activity. The mutant is unviable in normal air but grows well in air enriched with 0.9% CO2. In contrast, deletion of At5g47760 does not result in a visible phenotype, and leaf PGLP activity is unaltered. Sequencing of genomic DNA from another PGLP-deficient mutant revealed a combined missense and missplicing point mutation in At5g36700. These combined data establish At5g36700 as the gene encoding the photorespiratory PGLP, PGLP1.
Lipopolysaccharide promotes and augments metal allergies in mice, dependent on innate immunity and histidine decarboxylase
Authors: Sato N. , Kinbara M. , Kuroishi T. , Kimura K. , Iwakura Y. , Ohtsu H. , Sugawara S. , Endo Y.
Published: May 2007

Background
Few adequate murine models exist for metal allergies, it being especially difficult to induce Ni allergy in mice.

Objective
We examined the effect of lipopolysaccharide (LPS) on allergies to Ni and other metals in mice.

Methods
Ten days after sensitization with a metal salt and LPS, the ears were challenged with the same metal salt.

Results
LPS+NiCl2 (1 mm) was effective at sensitizing mice to Ni, LPS being effective at very low concentrations whether injected intradermally or intraperitoneally. The ear‐swelling response to Ni was more severe and more rapid in C57BL/6 mice than in BALB/c mice. In mast‐cell‐deficient mice, TNF‐α‐deficient mice, and interestingly even in nude (T cell deficient) mice, NiCl2+LPS induced a Ni allergy similar in degree to that in the respective control mice, but it induced Ni allergy only weakly in TLR4‐mutant mice, macrophage‐depleted mice, and IL‐1‐deficient mice. The activity of the histamine‐forming enzyme histidine decarboxylase (HDC) in the ears increased in parallel with ear swelling, and HDC‐deficient mice were resistant to ear swelling. Challenge with NiCl2+LPS augmented ear swelling (vs. NiCl2 alone). LPS induced effective sensitization to other metals (Cr, Co, Pd, or Ag).

Conclusions
These results indicate that in mice, LPS is a very important inducer of metal allergies, and potently promotes them (dependent on both innate immunity and HDC induction in cells other than mast cells). We discussed the idea that the bacterial environment is important for the establishment of metal allergies and for their provocation, and that the current thinking (including the contribution of T cells) should be reappraised in future studies.
Overexpression of suppressor of cytokine signalling‐5 augments eosinophilic airway inflammation in mice
Authors: Ohshima M. , Yokoyama A. , Ohnishi H. , Hamada H. , Kohno N. , Higaki J. , Naka T.
Published: May 2007

Background
Enhanced expression of the suppressor of cytokine signalling (SOCS)‐5 might be of therapeutic benefit for T‐helper type 2 (Th2) dominant diseases, as its expression is reported to result in a reduction of Th2 differentiation in vitro due to the inhibition of IL‐4 signalling.

Objective
To investigate the regulatory role of SOCS‐5 in vivo, we explored the phenotype of an experimental asthma model developed in SOCS‐5 transgenic (Tg) mice.

Methods
The SOCS‐5 Tg mice or wild‐type (WT) mice were sensitized and repeatedly challenged with ovalbumin (OVA). We examined bronchoalveolar lavage fluid (BALF), lung specimens, and airway hyperresponsiveness (AHR) to methacholine.

Results
The production of IFN‐γ by CD4+ T cells from unprimed SOCS‐5 Tg mice was significantly increased in comparison with unprimed wild‐type mice, indicating that SOCS‐5 Tg mice have a Th1‐polarizing condition under natural conditions. However, in an asthma model, significantly more eosinophils in the airways and higher levels of IL‐5 and IL‐13 in BALF were observed in the SOCS‐5 Tg than the wild‐type mice. AHR in the asthma model of SOCS‐5 Tg was also more enhanced than that of wild‐type mice. OVA‐stimulated CD4+ T cells from the primed SOCS‐5 Tg mice produced significantly more IL‐5 and IL‐13 than CD4+ T cells from wild‐type mice.

Conclusion
Our results demonstrate that the overexpression of SOCS‐5 does not inhibit Th2 response, but rather augments the phenotype of the asthma model in vivo. This finding throws into question the therapeutic utility of using enhancement of SOCS‐5 expression for Th2‐dominant disease.
Turnover of passerine birds on islands in the Aegean Sea (Greece)
Authors: Foufopoulos Johannes , Mayer Gregory C.
Published: April 2007

Aim We wish to determine the effect of migratory status on turnover rates in island birds. Because turnover is influenced by factors other than migratory status, we also considered the influence of body size and physical characteristics of the islands inhabited on the probabilities of extinction and immigration.

Location The Mediterranean islands of Delos, Astypalea, Paros, Naxos and Lesvos in the Aegean Sea, Greece.

Methods The passerine birds of these islands were surveyed between 1954 and 1961 by G.E. Watson, and were resurveyed between 1988 and 1992. The effects of migratory status and body size on the probabilities of extinction and immigration were examined byG‐tests of linear trend in proportion, and analysis of variance, respectively. A combined analysis of migratory status, body size and physical characteristics of the islands was carried out using logistic regressions of the probabilities of extinction and immigration on these factors.

Results Species number on each island changed little between surveys, with no island's species number changing by more than one species. Twelve population extinctions and 11 immigrations were recorded. The smallest island, Delos (6 km2), had the highest annualized relative turnover rate (1.08), while the four larger islands (96–1614 km2) had lower and mutually similar rates (0.21–0.27). Populations on higher elevation islands were less likely to go extinct. There is no evidence for an effect of body size on the probabilities of extinction or immigration. Migratory status affected extinction and immigration probabilities differently: migratory species were more likely to immigrate, but less likely to go extinct.

Main conclusions The position of the Aegean islands along a major north–south flyway may account for the observed effects of migratory status. The annual passage of large numbers of migrants may, via the rescue effect, decrease the chances of extinction, while at the same time increasing the chances of colonization of unoccupied islands. The likelihood of both extinction and immigration involves a complex interaction between life‐history traits and island characteristics. The effects of migratory status will depend not only on consideration of vagility, vulnerability and stochasticity identified by previous authors, but also upon the location of the islands in relationship to migratory pathways.
Resilient forest faunal communities in South Africa: a legacy of palaeoclimatic change and extinction filtering?
Authors: Lawes Michael J. , Eeley Harriet A. C. , Findlay Nicola J. , Forbes Dale
Published: April 2007

Aim To examine the influence of climatic extinction filtering during the last glacial maximum (LGM;c.18,000 yrbp) and of the subsequent recolonization of forest faunas on contemporary assemblage composition in southern African forests.

Location South Africa, Mozambique, Swaziland, Zimbabwe.

Methods Data comprised presence/absence by quarter‐degree grid cell for forest‐dependent and forest‐associated birds, non‐volant mammals and frogs. Twenty‐one forest subregions were assigned to one of three previously identified forest types: Afrotemperate, scarp, and Indian Ocean coastal belt. Differences among forest types were examined through patterns and gradients of species richness and endemism, assemblage similarity, species turnover, and coefficients of species dispersal direction. The influence of contemporary environment on assemblage composition was investigated using partial canonical correspondence analysis. Several alternative biogeographical hypotheses for the recolonization of forest faunas were tested.

Results Afrotemperate faunas are relatively species‐poor, have low species turnover, and are unsaturated and infiltrated by generalist species. In northern and central regions, communities are supplemented by recolonization from scarp forest refugia, and among frogs by autochthanous speciation in localized refugia. Scarp faunas are relatively species‐rich, contain many forest‐dependent species, have high species turnover, and overlap with coastal and Afrotemperate faunas. Coastal forests are relatively species‐rich with high species turnover.

Main conclusions Afrotemperate communities were affected most by climatic extinction filtering events. Scarp forests were Afrotemperate refugia during the LGM and are a contemporary overlap zone between Afrotemperate and coastal forest. Coastal faunas derive from post‐LGM colonization along the eastern seaboard from tropical East African refugia. The greatest diversity is achieved in scarp and coastal forest faunas in northern KwaZulu–Natal province. This historical centre of diversity has influenced the faunal diversity of nearly all other forests in South Africa. The response of vertebrate taxa to large‐scale, historical processes is dependent on their relative mobility: forest birds best illustrate patterns resulting from post‐glacial faunal dispersal, while among mammals and frogs the legacy of climatic extinction filtering remains stronger.
Severe cold agglutinin disease caused by recurrent monomorphic Epstein–Barr virus (EBV)‐associated post‐transplant lymphoproliferative disorder (PTLD), clonally related to an EBV‐negative plasmacytic hyperplasia in a pediatric multivisceral organ transplant recipient
Authors: Brunner Barbara , Kropshofer Gabriele , Ellemunter Helmut , Brunner Andrea , Mueller Thomas , Margreiter Raimund , Tzankov Alexandar
Published: April 2007

Abstract:  PTLD represent major post‐transplant complications. The major etiologic factor is EBV. Association with cold agglutinin disease has not been described so far. We report a three‐yr‐old girl who developed oligoclonal EBV‐negative plasmacytic hyperplasia as well as Coombs test‐positive anemia one yr after multivisceral organ transplantation, performed after subtotal bowel resection for colointestinal aganglionosis and liver cirrhosis resulting from long‐term parenteral nutrition. The patient was treated for plasmacytic hyperplasia with cyclophosphamide and prednisolone and achieved clinical remission. One yr later PTLD progressed possibly driven by EBV to DLBCL. The migration patterns of the amplified Ig heavy chain genes demonstrated a probable clonal relationship of the DLBCL to a clone almost present in the plasmacytic hyperplasia. This progression was accompanied by a rapid rise of cold agglutinin titers with symptoms of severe cold agglutinin disease, leading to right femoral and extern iliac vein thromboses requiring partial leg amputation. After four cycles of rituximab, cyclophosphamide, and prednisolone, the patient achieved complete PTLD remission and the cold agglutinins disappeared. Summarizing, PTLD may be accompanied by cold agglutinin disease, and both may be successfully treated by immuno‐chemotherapy. The appearance of cold agglutinins in transplant patients may indicate PTLD development.
Allogeneic hematopoietic stem cell transplantation in pediatric chronic myelogenous leukemia cases: Hacettepe experience
Authors: Unal Sule , Fidan Gulin , Tavil Betul , Çetin Mualla , Çetinkaya Duygu Uçkan
Published: April 2007

Abstract:  Recently, there are emerging reports on the beneficial effect of imatinib mesylate for pediatric CML patients; however, the general recommendation is that high‐risk CML patients with a human leukocyte antigen‐identical donor should be transplanted within the first 12 months after diagnosis. Herein, the data of 16 allogeneic HSCT in 14 children with CML were analyzed retrospectively. In the present study, three‐yr EFS was 54.1 ± 10.8% and three‐yr OS was found as 80.7 ± 12.5%.
Gene expression profile analysis of Drosophila melanogaster selected for resistance to environmental stressors
Authors: SØRENSEN J. G. , NIELSEN M. M. , LOESCHCKE V.
Published: April 2007

Here, we report a detailed analysis of changes in gene expression in Drosophila melanogaster selected for ecologically relevant environmental stress resistance traits. We analysed females from seven replicated selection regimes and one control regime using whole genome gene expression arrays. When compared with gene expression profiles of control lines, we were able to detect consistent selection responses at the transcript level in each specific selection regime and also found a group of differentially expressed genes that were changed among all selected lines. Replicated selection lines showed similar changes in gene expression (compared with controls) and thus showed that 10 generations of artificial selection give a clear signal with respect to the resulting gene expression profile. The changes in gene expression in lines selected for increased longevity, desiccation and starvation resistance, respectively, showed high similarities. Cold resistance‐selected lines showed little differentiation from controls. Different methods of heat selection (heat survival, heat knock down and constant 30 °C) showed little similarity verifying that different mechanisms are involved in high temperature adaptation. For most individual selection regimes, and in the comparison of all selected lines and controls, the gene expression changes were exclusively in one direction, although the different selection regimes varied in the direction of response. The responses to selection restricted to individual selection regimes can be interpreted as stress specific, whereas the response shared among all selected lines can be considered as a general stress response. Here, we identified genes belonging to both types of responses to selection for stress resistance.
Development of Prey Capture in the Indian False Vampire BatMegaderma Lyra
Authors: Raghuram Hanumanthan , Marimuthu Granapathy
Published: May 2007

We studied development of prey capture, under captive conditions, on five newly weaned Indian false vampire batsMegaderma lyra. We tested the hypothesis that the young bats are able to improve the ability of hunting by trial and error. An additional hypothesis was that their rate of prey consumption and method of handling prey improve with age. We separated the juveniles from their mothers and observed them individually at different ages. At 58 d of age,M. lyraroosted 2 m above floor level, flew down only towards moving frogs, landed >1 m away from them and returned to roosts without showing attempt to capture. At day 60, bats roosted at 50‐cm heights, landed approx. 1 m away from frogs and moved towards them. Although bats intercepted frogs, their attempts to capture were still unsuccessful. At day 62, bats landed <1 m from frogs, made similar attempts and most of them were successful. Bats carried frogs, roosted at heights of 100 cm and started consuming. Numbers of jumps made by frogs and attempts made by bats during successful captures decreased with increase in age of bats. Furthermore, the distance between landing sites of bats and places where frogs stayed during landings decreased with advancement of age. Until 75 d of age,M. lyradevoured frogs with legs‐first on significantly more occasions. After 75 d, most of the consumptions started with heads of frogs, similar to adults. Duration of feeding on single frogs was significantly longer compared with that of mothers until young were 75‐d old. The study revealed that juveniles were inefficient on localization, rate of consumption, and handling prey at earlier ages (e.g. 60 d). They became efficient on these behavioural components at later age, i.e. after 75 d. Thus, the results were in accordance with both the hypotheses. Bats did not respond to stationary frogs.
Use of vegetation chemical signals for digging orientation in the subterranean rodent Ctenomys talarum (Rodentia: Ctenomyidae)
Authors: Schleich Cristian E. , Zenuto Roxana
Published: May 2007

Sensory modalities involved in the localization and selection of food represent critical information for understanding the foraging behavior of subterranean rodents. The objective of this study was to determine if a subterranean rodent that forages on aboveground plant parts, Ctenomys talarum, is able to detect the presence of odorous chemicals released by the plants into the soil to guide its excavation, as has been shown for subterranean species that forage on roots and bulbs. Individuals were introduced into an artificial Y‐maze, whose arms were filled with sandy soil in which plants either had or had not been growing (control). Digging activity exhibited in each soil type was recorded. The following plant species, present in the natural habitat of C. talarum, were used: Panicum racemosum (three different concentrations), Cortadeira sp., Margiricarpus pignatus, Ambrosia sp. and Raphanus sativus. The individuals allocated more time to excavation in the soil in which vegetation had been growing in comparison with the control for the five analysed plant species, except in the case of P. racemosum at its lowest concentration. The number of individuals that completed excavation in the tube‐containing soil in which plants had been growing was significantly higher than in the tube‐containing soil in which no plants had been growing, with the exception of P. racemosum at its lowest concentration and R. sativus. The results of the present study suggest that C. talarum have the ability to use olfaction to orient their digging while foraging even though members of this species consume mainly aboveground plant parts.
Inhibitory effect of Hemidesmus indicus and its active principle 2‐hydroxy 4‐methoxy benzoic acid on ethanol‐induced liver injury
Authors: Saravanan Nadana , Nalini Namasivayam
Published: May 2007

The study evaluates the inhibitory activity of ethanolic root extract of Hemidesmus indicus (H. indicus) and its active principle 2‐hydroxy 4‐methoxy benzoic acid (HMBA) on liver fibrotic markers and characteristics such as collagen content, matrix metalloproteinases (MMPs) 2 and 9 in ethanol‐fed rats. Experimental groups were control, H. indicus (500 mg/kg body weight every day during the last 30 days), HMBA (200 μg/kg body weight every day during the last 30 days), alcohol (5 g/kg body weight by intragastric intubation everyday, i.e. throughout the experimental period of 60 days), alcohol plus H. indicus and alcohol plus HMBA. Ethanol administration significantly increased the levels of liver collagen and hydroxy proline content, cross‐linked fluorescence, shrinkage temperature and lipid peroxidation and significantly decreased the solubility of liver collagen and the ascorbic acid content when compared with control rats. On treatment with H. indicus and HMBA the ethanol‐fed rats showed significantly reduced levels of liver collagen and hydroxyproline content, cross‐linked fluorescence, shrinkage temperature and lipid peroxidation and enhanced solubility of liver collagen and ascorbic acid levels when compared with untreated ethanol‐fed rats. MMPs were extracted from the liver of control, H. indicus‐treated, HMBA‐treated, ethanol‐administered, ethanol with H. indicus‐coadministered and ethanol with HMBA‐coadministered rats. The inhibition was analyzed by gelatin zymography and the percentage of expression was determined by a gel documentation system. The activities of MMPs 2 and 9 were significantly increased in ethanol‐supplemented rats. Cotreatment of H. indicus/HMBA with ethanol showed significantly decreased activities of these enzymes when compared with those of the untreated rats. H. indicus/HMBA alone treatment showed no such significant alterations. Thus, our present study reveals the strong inhibitory activity of H. indicus and HMBA on the quantitative and qualitative properties of hepatic collagen and also MMPs involved in the extracellular matrix degradation during ethanol intoxication.
Sympathetic control of short‐term heart rate variability and its pharmacological modulation
Authors: Elghozi Jean‐Luc , Julien Claude
Published: May 2007

The static relationship between heart rate (HR) and the activity of either vagal or sympathetic nerves is roughly linear within the physiological range of HR variations. The dynamic control of HR by autonomic nerves is characterized by a fixed time delay between the onset of changes in nerve activity and the onset of changes in HR. This delay is much longer for sympathetically than for vagally mediated changes in HR. In addition, the kinetics of the HR responses shows the properties of a low‐pass filter with short (vagal) and long (sympathetic) time constants. These differences might be secondary to differences in nervous conduction times, width of synaptic cleft, kinetics of receptor activation and post‐receptor events. Because of the accentuated low‐pass filter characteristics of the HR response to sympathetic modulation, sympathetic influences are almost restricted to the very‐low‐frequency component of HR variability, but the chronotropic effects of vagal stimulation usually predominate over those of sympathetic stimulation in this frequency band. Oscillations in cardiac sympathetic nerve activity are not involved in respiratory sinus arrhythmia (high‐frequency component) and make a minor contribution to HR oscillations of approximately 10‐s period (low‐frequency component of approximately 0.1 Hz), at least in the supine position. In the latter case, HR oscillations are derived mainly from a baroreflex, vagally mediated response to blood pressure Mayer waves. Beta‐blockers and centrally acting sympathoinhibitory drugs share the ability to improve the baroreflex control of HR, possibly through vagal facilitation, which might be beneficial in several cardiovascular diseases.
Mortality of Department of Veterans Affairs Patients Undergoing Coronary Revascularization in Private Sector Hospitals
Authors: Vaughan‐Sarrazin Mary S. , Wakefield Bonnie , Rosenthal Gary E.
Published: April 2007

Objective. A limitation of studies comparing outcomes of Veterans Affairs (VA) and private sector hospitals is uncertainty about the methods of accounting for risk factors in VA populations. This study estimates whether use of VA services is a marker for increased risk by comparing outcomes of VA users and other patients undergoing coronary revascularization in private sector hospitals.

Data Sources. Males 67 years and older undergoing coronary artery bypass graft (CABG; n=687,936) surgery or percutaneous coronary intervention (PCI; n=664,124) during 1996–2002 were identified from Medicare administrative data. Patients using VA services during the 2 years preceding the Medicare admission were identified using VA administrative files.

Study Design. Thirty‐, 90‐, and 365‐day mortality were compared in patients who did and did not use VA services, adjusting for demographic and clinical risk factors using generalized estimating equations and propensity score analysis.

Results. Adjusted mortality after CABG was higher (p<.001) in VA users compared with nonusers at 30, 90, and 365 days: odds ratio (OR)=1.07 (95 percent confidence interval [CI], 1.03–1.11), 1.07 (95 percent CI, 1.04–1.10), and 1.09 (95 percent CI, 1.06–1.12), respectively. For PCI, mortality at 30 and 90 days was similar (p>.05) for VA users and nonusers, but was higher at 365 days (OR=1.09; 95 percent CI, 1.06–1.12). The increased risk of death in VA users was limited to patients with service‐connected disabilities or low incomes. Odds of death for VA users were slightly lower using samples matched by propensity scores.

Conclusions. A small difference in risk‐adjusted outcomes for VA users and nonusers undergoing revascularization in private sector hospitals was found. This difference reflects unmeasured severity in VA users undergoing revascularization in private sector hospitals.
The Effect of Three‐Tier Formulary Adoption on Medication Continuation and Spending among Elderly Retirees
Authors: Huskamp Haiden A. , Deverka Patricia A. , Landrum Mary Beth , Epstein Robert S. , McGuigan Kimberly A.
Published: April 2007

Objective. To assess the effect of three‐tier formulary adoption on medication continuation and spending among elderly members of retiree health plans.

Data Sources. Pharmacy claims and enrollment data on elderly members of four retiree plans that adopted a three‐tier formulary over the period July 1999 through December 2002 and two comparison plans that maintained a two‐tier formulary during this period.

Study Design. We used a quasi‐experimental design to compare the experience of enrollees in intervention and comparison plans. We used propensity score methods to match intervention and comparison users of each drug class and plan. We estimated repeated measures regression models for each class/plan combination for medication continuation and monthly plan, enrollee, and total spending. We estimated logit models of the probability of nonpersistent use, medication discontinuation, and medication changes.

Data Collection/Extraction Methods. We used pharmacy claims to create person‐level drug utilization and spending files for the year before and year after three‐tier adoption.

Principal Findings. Three‐tier formulary adoption resulted in shifting of costs from plan to enrollee, with relatively small effects on medication continuation. Although implementation had little effect on continuation on average, a small minority of patients were more likely to have gaps in use and discontinue use relative to comparison patients.

Conclusions. Moderate cost sharing increases from three‐tier formulary adoption had little effect on medication continuation among elderly enrolled in retiree health plans with relatively generous drug coverage.