bluuebunny/crossref_metadata_2025 huggingface dataset:
Piezoelectric enhancement of giant magnetoresistance in spin-valves with different magnetic anisotropies
Authors: Rizwan Syed , Zhang S. , Yu Tian , Zhao Y. G. , Han X. F.
Published: January 2013

The phenomenon of giant magnetoresistance (GMR) in spin-valves under applied magnetic field is well established. We present piezoelectric control of the GMR ratio at room temperature for standard multilayered spin-valve structure fabricated on (011)-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) piezoelectric substrate. Four samples namely, S1, S2, S3, and S4 were, respectively, fabricated such that the magnetic easy axis makes an initial angle of 0°, 30°, 45°, and 60° with magnetic field applied during measurement. For S1, the GMR ratio decreases under electric field whereas it increases for the samples making progressively larger initial magnetization angles with the external field. We suggest that for S1, magnetic alignment between the two magnetic layers decreases due to the rotation of bottom free layer magnetization resulting in the decrease of antiparallel resistance as well as the GMR ratio under applied electric field whereas for the other samples, the antiparallel resistance increases due to improvement in antiparallel alignment between the two magnetic layers causing increase in the GMR ratio at room temperature. Our results establish new way to control and even enhance the magnetoresistance via converse piezoelectric effect in spin-valves with different magnetic anisotropies.
Thermally induced Ostwald ripening of mesoporous Ge nanostructures
Authors: Tutashkonko S. , Nychyporuk T. , Lysenko V. , Lemiti M.
Published: January 2013

Mesoporous germanium (Ge) is a new nanostructured material with a very high potential for numerous applications. Thermally induced structural evolution of this nanomaterial is a key point for many high-temperature processes, such as epitaxy, for example, in which it can be involved. In this work, we investigate these structural changes occurring during thermal annealing in vacuum in temperature range between 250 and 650 °C. The influences of the annealing temperature and time as well as of the initial porous layer thickness on the morphology reorganization of the mesoporous Ge layer are described in detail. The obtained results are discussed in terms of Lifshitz-Slyozov-Wagner theory.
Hall mobility and photoconductivity in TlGaSeS crystals
Authors: Qasrawi A. F. , Gasanly N. M.
Published: January 2013

In this work, the fundamental properties of the TlGaSeS single crystals are investigated by means of temperature dependent electrical resistivity and Hall mobility. The crystal photo-responsibility as function of illumination intensity and temperature is also tested in the temperature range of 350-160 K. The study allowed the determination of acceptor centers as 230 and 450 meV below and above 260 K, and recombination centers as 181, 363, and 10 meV at low, moderate, and high temperatures, respectively. While the temperature-dependent Hall mobility behaved abnormally, the photoconductivity analysis reflected an illumination intensity dependent recombination center. Namely, the recombination center increased from 10 to 90 meV as the light intensity increased from 27.9 to 76.7 mW cm−2, respectively. That strange behavior was attributed to the temporary shift in Fermi level caused by photoexcitation.
Enhanced external quantum efficiency in rectangular single nanowire solar cells
Authors: Li Xiaofeng , Zhan Yaohui
Published: January 2013

Single-nanowire solar cells (SNSCs) in lying configuration can have external quantum efficiency (EQE) over 100% but always in narrowbands with EQE peaks slightly exceeding unit. We presented a rectangular gallium arsenide (GaAs) SNSC, which provides light absorption efficiency (Qabs) and EQE far beyond 100% for both transverse electric and magnetic illuminations, by optimally engineering the nanowires and introducing an advanced nanoshell design. Electromagnetic and carrier transport calculations show that Qabs and EQE peaks of the designed SNSCs can both be over 200% with averaged EQE ∼ 150% in most of the active spectral band of GaAs.
Frame assisted H2O electrolysis induced H2 bubbling transfer of large area graphene grown by chemical vapor deposition on Cu
Authors: de la Rosa César J. Lockhart , Sun Jie , Lindvall Niclas , Cole Matthew T. , Nam Youngwoo , Löffler Markus , Olsson Eva , Teo Kenneth B. K. , Yurgens August
Published: January 2013

An improved technique for transferring large area graphene grown by chemical vapor deposition on copper is presented. It is based on mechanical separation of the graphene/copper by H2 bubbles during H2O electrolysis, which only takes a few tens of seconds while leaving the copper cathode intact. A semi-rigid plastic frame in combination with thin polymer layer span on graphene gives a convenient way of handling- and avoiding wrinkles and holes in graphene. Optical and electrical characterizations prove the graphene quality is better than that obtained by traditional wet etching transfer. This technique appears to be highly reproducible and cost efficient.
Interfacial bonding and electronic structure of HfO2/GaSb interfaces: A first principles study
Authors: Xiong K. , Wang W. , Zhernokletov D. M. , K. C. Santosh , Longo R. C. , Wallace R. M. , Cho K.
Published: January 2013

The interfacial bonding and electronic structure of HfO2/GaSb interfaces has been investigated through first principles calculations. The calculated electronic structures of these interfaces reveal that some O-rich interfaces are semiconducting interfaces without any gap states. In contrast, for the interfaces with lower interfacial O content, gap states appear in the GaSb band gap, close to the conduction band. The valence band offsets are found to vary from 2.2 eV to 3.6 eV, depending on the interfacial O content. Our results suggest that GaSb is a suitable material to form high quality interface with HfO2.
Controlling interfacial states in amorphous/crystalline LaAlO3/SrTiO3 heterostructures by electric fields
Authors: Christensen D. V. , Trier F. , Chen Y. Z. , Smith A. , Nygård J. , Pryds N.
Published: January 2013

The tunable metal-insulator transition in crystalline LaAlO3/SrTiO3 heterostructures constitutes a central element in the range of remarkable interface properties that has made this oxide system subject to extensive research. Recently, metallic interfaces have also been realized when depositing amorphous LaAlO3 films on SrTiO3. Here, we present a non-volatile and reversible tuning of the interface conductivity by more than 3 orders of magnitude at room temperature by applying an electric field to such amorphous/crystalline heterostructures with amorphous LaAlO3 film thicknesses of ∼2 nm. We show that the tunability is strongly temperature dependent, and demonstrate a simple protocol for enhancing the tunability.
Landau-Lifshitz-Bloch-Slonczewski simulations of the spin-transfer-torque driven magnetization switching assisted by Joule heating
Authors: Oniciuc Eugen , Stoleriu Laurentiu , Stancu Alexandru
Published: January 2013

In this paper, we show that Landau-Lifshitz-Bloch-Slonczewski equation can be envisaged as one of the best options for the modeling of heat assisted spin transfer torque writing. The model is tested on a Joule assisted switching problem for a macrospin under a polarized current, with all the values for the parameters in the typical range used technologically. The switching diagram in the presence of the current is presented, explained, and the agreement with published experimental data is discussed.
Damping of CoxFe80−xB20 ultrathin films with perpendicular magnetic anisotropy
Authors: Devolder T. , Ducrot P.-H. , Adam J.-P. , Barisic I. , Vernier N. , Kim Joo-Von , Ockert B. , Ravelosona D.
Published: January 2013

We use vector network analyzer ferromagnetic resonance to study the perpendicularly magnetized CoFeB films. We report the dependence of the anisotropy, the g-factor, and the damping upon the Fe-Co compositional ratio in the amorphous and crystalline states. The damping and the anisotropy increase upon crystallization but vary little with composition on the Fe-rich side. At high cobalt content, the anisotropy lowers while the damping and the sample inhomogeneity increase. The compositional dependences seem to extrapolate from the properties of bulk CoFe alloys, with differences that can be understood from the correlated impacts of spin-orbit interaction on anisotropy, g-factor, and damping.
High current stress effects in amorphous-InGaZnO4 thin-film transistors
Authors: Mativenga Mallory , Hong Sejin , Jang Jin
Published: January 2013

Amorphous-InGaZnO4 (a-IGZO) thin-film transistors (TFTs) on glass undergo large positive threshold voltage shifts (ΔVTH) under high current stress (HCS)—a consequence of Joule heating of the active-layer. Here, we show that when the active layer is split into smaller parts, HCS induces negligible ΔVTH. When the active layer heats up during HCS, conducting electrons in the channel gain enough energy to surmount the energy barrier at the active-layer/gate-insulator interface and become trapped into deep states inside the gate-insulator. Splitting the active-layer into smaller parts increases the surface area for heat dissipation, resulting in the elimination of these self-heating effects.
Feedback-controlled electromigration for the fabrication of point contacts
Authors: Campbell J. M. , Knobel R. G.
Published: January 2013

Lithographically fabricated point contacts serve as important examples of mesoscopic conductors, as electrodes for molecular electronics, and as ultra-sensitive transducers for mechanical motion. We have developed a reproducible technique for fabricating metallic point contacts through electromigration. We employ fast analog feedback in a four-wire configuration in combination with slower computer controlled feedback to avoid catastrophic instability. This hybrid system allows electromigration to proceed while dissipating approximately constant power in the wire. We are able to control the final resistance of the point contact precisely below 5 kΩ and to within a factor of three when the target resistance approaches 12 kΩ where only a single conducting channel remains.
Lévy noise induced switch in the gene transcriptional regulatory system
Authors: Xu Yong , Feng Jing , Li JuanJuan , Zhang Huiqing
Published: January 2013

The study of random fluctuations in a gene transcriptional regulatory system is extended to the case of non-Gaussian Lévy noise, which can describe unpredictable jump changes of the random environment. The stationary probability densities are given to explore the key roles of Lévy noise in a gene transcriptional regulatory system. The results demonstrate that the parameters of Lévy noise, including noise intensity, stability index, and skewness parameter, can induce switches between distinct gene-expression states. A further concern is the switching time (from the high concentration state to the low concentration one or from the low concentration state to the high concentration one), which is a random variable and often referred to as the mean first passage time. The effects of Lévy noise on expression and degradation time are studied by computing the mean first passage time in two directions and a number of different peculiarities of non-Gaussian Lévy noise compared with Gaussian noise are observed.
Merging of high speed argon plasma jets
Authors: Case A. , Messer S. , Brockington S. , Wu L. , Witherspoon F. D. , Elton R.
Published: January 2013

Formation of an imploding plasma liner for the plasma liner experiment (PLX) requires individual plasma jets to merge into a quasi-spherical shell of plasma converging on the origin. Understanding dynamics of the merging process requires knowledge of the plasma phenomena involved. We present results from the study of the merging of three plasma jets in three dimensional geometry. The experiments were performed using HyperV Technologies Corp. 1 cm Minirailguns with a preionized argon plasma armature. The vacuum chamber partially reproduces the port geometry of the PLX chamber. Diagnostics include fast imaging, spectroscopy, interferometry, fast pressure probes, B-dot probes, and high speed spatially resolved photodiodes, permitting measurements of plasma density, temperature, velocity, stagnation pressure, magnetic field, and density gradients. These experimental results are compared with simulation results from the LSP 3D hybrid PIC code.
Resonance mixing of alternating current magnetic fields in a multiferroic composite
Authors: Burdin D. A. , Chashin D. V. , Ekonomov N. A. , Fetisov Y. K. , Fetisov L. Y. , Sreenivasulu G. , Srinivasan G.
Published: January 2013

Theory for nonlinear mixing of harmonic magnetic fields in a ferromagnetic-ferroelectric composite structure has been developed and compared with data. In the voltage response of the composite, the model predicts a dc voltage proportional to the magnetostriction λ and its second derivative p with respect to the bias field H, an ac voltage due to linear magnetoelectric effect that is proportional to the piezomagnetic coefficient q, and a third term due to nonlinear mixing of the ac magnetic fields that is proportional to p. Doubling of the frequency and generation of voltages with sum and difference frequencies are expected due to nonlinearity of λ (H). The theoretically predicted effects are investigated in a sample of amorphous ferromagnetic film FeBSiC and a bimorph of lead zirconate titanate. Both the efficiency of frequency doubling and nonlinear mixing of the ac magnetic fields are found to be proportional to p. The effects discussed here are of interest for magnetic field sensors and signal processing devices such as mixers, frequency doublers, frequency dividers, and modulators.
Photoinduced scalar and vectorial optical phenomena in nano-dimensional glassy chalcogenide films and their liquid crystal photoalignment
Authors: Klebanov M. , Lyubin V. , Gelbaor Kirzhner M. , Abdulhalim I.
Published: January 2013

Photoinduced (PI) scalar and vectorial optical phenomena in chalcogenide glassy films' early studies were performed on films thicker than 0.5–l μm. Recent finding of nano-dimensional (ND) As2S3 films possibility to act as a photoalignment layer for nematic liquid crystals (LCs) made careful investigation of PI anisotropy and other PI phenomena in nano-dimensional (<100 nm thick) chalcogenide films of different composition. Results of such investigation are considered in this paper. The scalar and vectorial PI phenomena having many similar characteristics are shown to exist in all studied (ND) As-containing chalcogenide glassy films both stoichiometric and non-stoichiometric. The ND Ge-containing chalcogenide glassy films are shown to have very different optical characteristics. We demonstrated that ND chalcogenide glassy films of different compositions are able to act as photoalignment layers for nematic LCs under irradiation with linearly polarized light.
Electron mobility of ultrathin InN on yttria-stabilized zirconia with two-dimensionally grown initial layers
Authors: Okubo Kana , Kobayashi Atsushi , Ohta Jitsuo , Oshima Masaharu , Fujioka Hiroshi
Published: January 2013

An In-polar InN ultrathin film with high electron mobility was grown on an insulating yttria-stabilized zirconia (YSZ) (111) substrate via precise control of growth conditions for initial monolayers. It was found that the first several monolayers of InN on YSZ can be grown in a two-dimensional mode using extremely N-rich (ex-N-rich) conditions. Although the growth of more than several InN monolayers under these conditions results in rough surfaces, probably because of the suppressed migration of In atoms on the surface, the combination of ex-N-rich growth for the first few monolayers with subsequent conventional In-rich growth leads to the successful formation of InN films with smooth surfaces. The electron mobility of 11-nm-thick InN on YSZ with two-dimensionally grown initial layers was 170 cm2 V−1 s−1, which is much higher than the best reported value for InN ultrathin layers grown on GaN substrates. These results indicate that the structural quality of the InN/YSZ heterointerface and a smooth surface are inherently important for obtaining InN ultrathin films with good transport properties.
Nitrogen-passivated dielectric/InGaAs interfaces with sub-nm equivalent oxide thickness and low interface trap densities
Authors: Chobpattana Varistha , Son Junwoo , Law Jeremy J. M. , Engel-Herbert Roman , Huang Cheng-Ying , Stemmer Susanne
Published: January 2013

We report on the electrical characteristics of HfO2 and HfO2/Al2O3 gate dielectrics deposited on n-In0.53Ga0.47As by atomic layer deposition, after in-situ hydrogen or nitrogen plasma surface cleaning procedures, respectively. It is shown that alternating cycles of nitrogen plasma and trimethylaluminum prior to growth allow for highly scaled dielectrics with equivalent oxide thicknesses down to 0.6 nm and interface trap densities that are below 2.5 × 1012 cm−2 eV−1 near midgap. It is shown that the benefits of the nitrogen plasma surface cleaning procedure are independent of the specific dielectric.
Single-shot 35 fs temporal resolution electron shadowgraphy
Authors: Scoby C. M. , Li R. K. , Threlkeld E. , To H. , Musumeci P.
Published: January 2013

We obtain single-shot time-resolved shadowgraph images of the electromagnetic fields resulting from the interaction of a high intensity ultrashort laser pulse with a metal surface. Using a high brightness relativistic electron beam and a high streaking speed radiofrequency deflector, we report <35 fs temporal resolution enabling a direct visualization of the retarded-time dominated field evolution which follows the laser-induced charge emission. A model including the finite signal propagation speed well reproduces the data and yields measurements of fundamental parameters in short pulse laser-matter interaction such as the amount of emitted charge and the emission time scale.
Small amplitude nonlinear electron acoustic solitary waves in weakly magnetized plasma
Authors: Dutta Manjistha , Ghosh Samiran , Roychoudhury Rajkumar , Khan Manoranjan , Chakrabarti Nikhil
Published: January 2013

Nonlinear propagation of electron acoustic waves in homogeneous, dispersive plasma medium with two temperature electron species is studied in presence of externally applied magnetic field. The linear dispersion relation is found to be modified by the externally applied magnetic field. Lagrangian transformation technique is applied to carry out nonlinear analysis. For small amplitude limit, a modified KdV equation is obtained, the modification arising due to presence of magnetic field. For weakly magnetized plasma, the modified KdV equation possesses stable solitary solutions with speed and amplitude increasing temporally. The solutions are valid upto some finite time period beyond which the nonlinear wave tends to wave breaking.
Evidence of ultra-low-k dielectric material degradation and nanostructure alteration of the Cu/ultra-low-k interconnects in time-dependent dielectric breakdown failure
Authors: Lam Jeffrey C. K. , Huang Maggie Y. M. , Hau Ng Tsu , Khalid Bin Dawood Mohammed , Zhang Fan , Du Anyan , Sun Handong , Shen Zexiang , Mai Zhihong
Published: January 2013

Ultra-low-k time-dependent dielectric breakdown (TDDB) is one of the most important reliability issues in Cu/low-k technology development due to its weaker intrinsic breakdown strength compared to SiO2 dielectrics. With continuous technology scaling, this problem is further exacerbated for Cu/ultra-low-k interconnects. In this letter, the TDDB degradation behavior of ultra-low-k dielectric in Cu/ultra-low-k interconnects will be investigated by a method consisting of a combination of Raman with Fourier transform infrared vibrational microscopes. In TDDB tests on Cu/low-k interconnect, it was found that intrinsic degradation of the ultra-low-k dielectric would first occur under electrical field stress. Upon further electrical field stress, the ultra-low-k dielectric degradation would be accelerated due to Ta ions migration from the Ta/TaN barrier bi-layer into the ultra-low-k dielectrics. In addition, no out-diffusion of Cu ions was observed in our investigation on Cu/Ta/TaN/SiCOH structures.
Temperature and Co thickness dependent sign change of the anomalous Hall effect in Co/Pd multilayers: An experimental and theoretical study
Authors: Keskin V. , Aktaş B. , Schmalhorst J. , Reiss G. , Zhang H. , Weischenberg J. , Mokrousov Y.
Published: January 2013

The anomalous Hall effect in ultra-thin {Co0.3 nm/Pd0.5 nm}n multilayers has been investigated recently with respect to surface and interface contributions [Guo et al., Phys. Rev. B 86, 104433 (2012)]. In this work, we observe a Co thickness and temperature dependent sign change also for {Co0.20–0.55 nm/Pd1.5nm or 1.8 nm}9x multilayers, e.g., in layer stacks with considerably thicker Pd layers and hence lower resistivity. The thickness dependent behavior can be reproduced by ab initio calculations of the Hall conductivity, for which only interfacial and bulk contributions play a role.
Potential of low pressure agricultural waste briquettes: An alternative energy source for cooking in Nigeria
Authors: Kuhe A. , Ibiang F. A. , Igbong D. I.
Published: January 2013

In this study, the variation of steady-state combustion rate (otherwise called normalized burn rate, NBR) with the density, moisture content, and geometry of sawdust, palm fibre and rice husk briquettes, burned in free air was investigated. The quest for alternative fuel for heating and cooking as a result of depletion of fossil fuel and environmental pollution associated with its burning has necessitated the need to improve on the use of loose agro-waste as alternative in Nigeria. Cylindrical briquettes were used through out the experiment except for the effect of geometry where cylindrical briquettes with central hole and cylindrical solid briquettes were used. The briquettes were formed by compression of the pulp in the mould with an Instron compression test machine at a pressure range between 1.5 and 7.5 N mm−2 which formed briquettes with densities between 200 and 500 kg m−3. The results show that the NBR for the three selected briquette samples: wood sawdust, palm fibre, and rice husk, respectively, was found to decrease as the density and moisture content increases. It was observed that hollow briquette had a higher NBR than that of solid briquette of the same pressure and relaxed diameter with sawdust having the highest variation and rice husk the least. The results show that briquettes could be a viable alternative to fuel wood.
Continuous Flow Synthesis of Difluoroamine Systems by Direct Fluorination
Authors: McPake Christopher B. , Murray Christopher B. , Sandford Graham
Published: January 2013

Continuous flow methodology for the synthesis of perfluoroaryl difluoroamine derivatives by reaction of fluorine gas with an appropriate perfluoroaniline substrate is described, further demonstrating the efficient use of flow regimes for reactions involving highly reactive and toxic reagents.
Centennial-scale fluctuations and regional complexity characterize Pacific salmon population dynamics over the past five centuries
Authors: Rogers Lauren A. , Schindler Daniel E. , Lisi Peter J. , Holtgrieve Gordon W. , Leavitt Peter R. , Bunting Lynda , Finney Bruce P. , Selbie Daniel T. , Chen Guangjie , Gregory-Eaves Irene , Lisac Mark J. , Walsh Patrick B.
Published: January 2013

Observational data from the past century have highlighted the importance of interdecadal modes of variability in fish population dynamics, but how these patterns of variation fit into a broader temporal and spatial context remains largely unknown. We analyzed time series of stable nitrogen isotopes from the sediments of 20 sockeye salmon nursery lakes across western Alaska to characterize temporal and spatial patterns in salmon abundance over the past ∼500 y. Although some stocks varied on interdecadal time scales (30- to 80-y cycles), centennial-scale variation, undetectable in modern-day catch records and survey data, has dominated salmon population dynamics over the past 500 y. Before 1900, variation in abundance was clearly not synchronous among stocks, and the only temporal signal common to lake sediment records from this region was the onset of commercial fishing in the late 1800s. Thus, historical changes in climate did not synchronize stock dynamics over centennial time scales, emphasizing that ecosystem complexity can produce a diversity of ecological responses to regional climate forcing. Our results show that marine fish populations may alternate between naturally driven periods of high and low abundance over time scales of decades to centuries and suggest that management models that assume time-invariant productivity or carrying capacity parameters may be poor representations of the biological reality in these systems.
Frequency and intensity of productivity regime shifts in marine fish stocks
Authors: Vert-pre Katyana A. , Amoroso Ricardo O. , Jensen Olaf P. , Hilborn Ray
Published: January 2013

Fish stocks fluctuate both in abundance and productivity (net population increase), and there are many examples demonstrating that productivity increased or decreased due to changes in abundance caused by fishing and, alternatively, where productivity shifted between low and high regimes, entirely unrelated to abundance. Although shifts in productivity regimes have been described, their frequency and intensity have not previously been assessed. We use a database of trends in harvest and abundance of 230 fish stocks to evaluate the proportion of fish stocks in which productivity is primarily related to abundance vs. those that appear to manifest regimes of high or low productivity. We evaluated the statistical support for four hypotheses: (i) the abundance hypothesis, where production is always related to population abundance; (ii) the regimes hypothesis, where production shifts irregularly between regimes that are unrelated to abundance; (iii) the mixed hypothesis, where even though production is related to population abundance, there are irregular changes in this relationship; and (iv) the random hypothesis, where production is random from year to year. We found that the abundance hypothesis best explains 18.3% of stocks, the regimes hypothesis 38.6%, the mixed hypothesis 30.5%, and the random hypothesis 12.6%. Fisheries management agencies need to recognize that irregular changes in productivity are common and that harvest regulation and management targets may need to be adjusted whenever productivity changes.
Toll-like receptor 4 stimulation with the detoxified ligand monophosphoryl lipid A improves Alzheimer’s disease-related pathology
Authors: Michaud Jean-Philippe , Hallé Maxime , Lampron Antoine , Thériault Peter , Préfontaine Paul , Filali Mohammed , Tribout-Jover Pascale , Lanteigne Anne-Marie , Jodoin Rachel , Cluff Christopher , Brichard Vincent , Palmantier Rémi , Pilorget Anthony , Larocque Daniel , Rivest Serge
Published: January 2013

Alzheimer’s disease (AD) is the most common cause of dementia worldwide. The pathogenesis of this neurodegenerative disease, currently without curative treatment, is associated with the accumulation of amyloid β (Aβ) in brain parenchyma and cerebral vasculature. AD patients are unable to clear this toxic peptide, leading to Aβ accumulation in their brains and, presumably, the pathology associated with this devastating disease. Compounds that stimulate the immune system to clear Aβ may therefore have great therapeutic potential in AD patients. Monophosphoryl lipid A (MPL) is an LPS-derived Toll-like receptor 4 agonist that exhibits unique immunomodulatory properties at doses that are nonpyrogenic. We show here that repeated systemic injections of MPL, but not LPS, significantly improved AD-related pathology in APP
swe
/PS1 mice. MPL treatment led to a significant reduction in Aβ load in the brain of these mice, as well as enhanced cognitive function. MPL induced a potent phagocytic response by microglia while triggering a moderate inflammatory reaction. Our data suggest that the Toll-like receptor 4 agonist MPL may be a treatment for AD.
Acidocalcisomes of
Trypanosoma brucei
have an inositol 1,4,5-trisphosphate receptor that is required for growth and infectivity
Authors: Huang Guozhong , Bartlett Paula J. , Thomas Andrew P. , Moreno Silvia N. J. , Docampo Roberto
Published: January 2013

Acidocalcisomes are acidic calcium stores rich in polyphosphate and found in a diverse range of organisms. The mechanism of Ca
2+
release from these organelles was unknown. Here we present evidence that
Trypanosoma brucei
acidocalcisomes possess an inositol 1,4,5-trisphosphate receptor (TbIP
3
R) for Ca
2+
release. Localization studies in cell lines expressing
TbIP

3

R
in its endogenous locus fused to an epitope tag revealed its partial colocalization with the vacuolar proton pyrophosphatase, a marker of acidocalcisomes. IP
3
was able to stimulate Ca
2+
release from a chicken B-lymphocyte cell line in which the genes for all three vertebrate IP
3
Rs have been stably ablated (DT40-3KO) and that were stably expressing
TbIP

3

R
, providing evidence of its function. IP
3
was also able to release Ca
2+
from permeabilized trypanosomes or isolated acidocalcisomes and photolytic release of IP
3
in intact trypanosomes loaded with Fluo-4 elicited a transient Ca
2+
increase in their cytosol. Ablation of
TbIP

3

R
by RNA interference caused a significant reduction of IP
3
-mediated Ca
2+
release in trypanosomes and resulted in defects in growth in culture and infectivity in mice. Taken together, the data provide evidence of the presence of a functional IP
3
R as a Ca
2+
release channel in acidocalcisomes of trypanosomes and suggest that a Ca
2+
signaling pathway that involves acidocalcisomes is required for growth and establishment of infection.
Generation of functional eggs and sperm from cryopreserved whole testes
Authors: Lee Seungki , Iwasaki Yoshiko , Shikina Shinya , Yoshizaki Goro
Published: January 2013

The conservation of endangered fish is of critical importance. Cryobanking could provide an effective backup measure for use in conjunction with the conservation of natural populations; however, methodology for cryopreservation of fish eggs and embryos has not yet been developed. The present study established a methodology capable of deriving functional eggs and sperm from frozen type A spermatogonia (ASGs). Whole testes taken from rainbow trout were slowly frozen in a cryomedium, and the viability of ASGs within these testes did not decrease over a 728-d freezing period. Frozen-thawed ASGs that were intraperitoneally transplanted into sterile triploid hatchlings migrated toward, and were incorporated into, recipient genital ridges. Transplantability of ASGs did not decrease after as much as 939 d of cryopreservation. Nearly half of triploid recipients produced functional eggs or sperm derived from the frozen ASGs and displayed high fecundity. Fertilization of resultant gametes resulted in the successful production of normal, frozen ASG-derived offspring. Feasibility and simplicity of this methodology will call for an immediate application for real conservation of endangered wild salmonids.
Using model-based functional MRI to locate working memory updates and declarative memory retrievals in the fronto-parietal network
Authors: Borst Jelmer P. , Anderson John R.
Published: January 2013

In this study, we used model-based functional MRI (fMRI) to locate two functions of the fronto-parietal network: declarative memory retrievals and updating of working memory. Because regions in the fronto-parietal network are by definition coherently active, locating functions within this network is difficult. To overcome this problem, we applied model-based fMRI, an analysis method that uses predictions of a computational model to inform the analysis. We applied model-based fMRI to five previously published datasets with associated computational cognitive models, and subsequently integrated the results in a meta-analysis. The meta-analysis showed that declarative memory retrievals correlated with activity in the inferior frontal gyrus and the anterior cingulate, whereas updating of working memory corresponded to activation in the inferior parietal lobule, as well as to activation around the inferior frontal gyrus and the anterior cingulate.
Cognitive therapy for depression: Coping style matters
Authors: Renaud Jesse , Dobson Keith S. , Drapeau Martin
Published: January 2013

Aim: The finding by Jacobson and colleagues that there was no difference in treatment outcome for individuals treated with a complete cognitive therapy (CT) package and those receiving behavioural activation raised serious concerns about the mediational role of cognition in depression. The present study was designed to test whether the interaction between coping and cognition predicts changes in depressive symptomatology. Method: The sample (N=30) was derived from the full CT condition of the study conducted by Jacobson and colleagues. Therapy transcripts from the third session were rated to assess cognitive errors and coping. Change in depression scores from pre‐treatment to post‐treatment was computed. Findings: Analyses demonstrated that engagement in self‐reliance and not engaging in escape coping predicted greater decreases in levels of depression after CT. Implications for practice: These findings suggest that engaging in specific types of adaptive coping strategies and avoiding maladaptive coping may be important in predicting decreases in depression for individuals who have high levels of certain cognitive errors.
Effects of age, sex and activity level on counter‐movement jump performance in children and adolescents
Authors: Focke Anne , Strutzenberger Gerda , Jekauc Darko , Worth Annette , Woll Alexander , Schwameder Hermann
Published: January 2013

The aim of this study was to investigate counter‐movement jump performance and its reliability in children and adolescents with respect to age, sex and activity level. We tested 1835 children and adolescents aged between 4 and 17 years. All participants performed three counter‐movement jumps on a force platform with arms akimbo. The participants were divided into six age groups and subdivided by sex within each group, to analyse age and sex effects. Subsequently, jumping performance of active and sedentary participants was compared. Jump height was calculated and the highest jump out of three was used for the calculations of peak force and peak rate of force development. Variability of all parameters was quantified using the coefficient of variation over all jumps. Jump height increased significantly with increasing age while peak rate of force development decreased. Peak force was similar for all age groups. Jump height was significantly higher in male participants and peak force and peak rate of force development was significantly lower in male participants. Variability of jump height and peak force decreased significantly with increasing age leading to reliable data above the age of 10 years. Peak rate of force development showed a high variability and, therefore, should be interpreted with caution. This could be useful information for coaches as they need to know from which age onwards the counter‐movement jump is applicable in performance diagnostics and which parameters are sensible for interpretation. Finally, the present study provides data to be used as normative references.
Islamic Feminism: a new feminist movement or a strategy by women for acquiring rights?
Authors: Grami Amal
Published: January 2013

This article focuses on the phenomenon of Islamic feminism. It provides a detailed summary of the defining theories and objectives of the movement and its role in contributing to raising awareness and as an agent for change as well. It highlights the expanding boundaries of the phenomenon and the implications this has had on its content, orientation, and role in a world where globalization and Islamophobia are affecting the process of developing Islamic feminism. The article traces the factors that contributed to the rise of Islamic feminism and explores how these interacted to produce the phenomenon in the changing contexts. It analyses the inherent problems in the movement and its argument from a critical point of view. The article concludes by asking a number of questions that help in understanding the nature and the limitations of Islamic feminism, its role, social, religious, political and academic implications.
Poststructuralist theory and women in the Middle East: going in circles?
Authors: Lazreg Marnia
Published: January 2013

This article examines the effects of the uncritical use of the poststructuralist Foucauldian theoretical approach on studies of Middle Eastern women and gender. Focusing on the twin concepts of ‘empowerment’ and ‘resistance’ as they have been applied to account for the re-veiling trend among Muslim countries and communities, it explores the epistemic transformation of the explanation of this trend into its justification. It further provides an example of a historicized application of Michel Foucault’s conception of power.
Chromosomal gain promotes formation of a steep RanGTP gradient that drives mitosis in aneuploid cells
Authors: Hasegawa Keisuke , Ryu Sung Jin , Kaláb Petr
Published: January 2013

Many mitotic factors were shown to be activated by Ran guanosine triphosphatase. Previous studies in Xenopus laevis egg extracts and in highly proliferative cells showed that mitotic chromosomes were surrounded by steep Ran guanosine triphosphate (GTP) concentration gradients, indicating that RanGTP-activated factors promote spindle assembly around chromosomes. However, the mitotic role of Ran in normal differentiated cells is not known. In this paper, we show that although the steep mitotic RanGTP gradients were present in rapidly growing cell lines and were required for chromosome congression in mitotic HeLa cells, the gradients were strongly reduced in slow-growing primary cells, such as HFF-1 fibroblasts. The overexpression of RCC1, the guanine nucleotide exchange factor for Ran, induced steeper mitotic RanGTP gradients in HFF-1 cells, showing the critical role of RCC1 levels in the regulation of mitosis by Ran. Remarkably, in vitro fusion of HFF-1 cells produced cells with steep mitotic RanGTP gradients comparable to HeLa cells, indicating that chromosomal gain can promote mitosis in aneuploid cancer cells via Ran.
Findings of the International Nosocomial Infection Control Consortium (INICC), Part III Effectiveness of a Multidimensional Infection Control Approach to Reduce Central Line—Associated Bloodstream Infections in the Neonatal Intensive Care Units of 4 Developing Countries
Authors: Rosenthal Victor Daniel , Dueñas Lourdes , Sobreyra-Oropeza Martha , Ammar Khaldi , Navoa-Ng Josephine Anne , Casares Ana Conceptión Bran de , Machuca Lilian de Jesús , Ben-Jaballah Nejla , Hamdi Asma , Villanueva Victoria D. , Tolentino María Corazon V.
Published: January 2013

Objective.

To analyze the impact of the International Nosocomial Infection Control Consortium (INICC) multidimensional infection control approach to reduce central line-associated bloodstream infection (CLABSI) rates.

Setting.

Four neonatal intensive care units (NICUs) of INICC member hospitals from El Salvador, Mexico, Philippines, and Tunisia.

Patients.

A total of 2,241 patients hospitalized in 4 NICUs for 40,045 bed-days.

Methods.

We conducted a before-after prospective surveillance study. During Phase 1 we performed active surveillance, and during phase 2 the INICC multidimensional infection control approach was implemented, including the following practices: (1) central line care bundle, (2) education, (3) outcome surveillance, (4) process surveillance, (5) feedback of CLABSI rates, and (6) performance feedback of infection control practices. We compared CLABSI rates obtained during the 2 phases. We calculated crude stratified rates, and, using random-effects Poisson regression to allow for clustering by ICU, we calculated the incidence rate ratio (IRR) for each follow-up time period compared with the 3-month baseline.

Results.

During phase 1 we recorded 2,105 CL-days, and during phase 2 we recorded 17,117 CL-days. After implementation of the multidimensional approach, the CLABSI rate decreased by 55%, from 21.4 per 1,000 CL-days during phase 1 to 9.7 per 1,000 CL-days during phase 2 (rate ratio, 0.45 [95% confidence interval, 0.33–0.63]). The IRR was 0.53 during the 4–12-month period and 0.07 during the final period of the study (more than 45 months).

Conclusions.

Implementation of a multidimensional infection control approach was associated with a significant reduction in CLABSI rates in NICUs.
Finitely Suslinian models for planar compacta with applications to Julia sets
Authors: Blokh Alexander , Curry Clinton , Oversteegen Lex
Published: January 2013

A compactum

X
⊂

C

X\subset \mathbb {C}

is unshielded if it coincides with the boundary of the unbounded component of

C

∖
X

\mathbb {C}\setminus X

. Call a compactum

X
X

finitely Suslinian if every collection of pairwise disjoint subcontinua of

X
X

whose diameters are bounded away from zero is finite. We show that any unshielded planar compactum

X
X

admits a topologically unique monotone map

m
X

:
X
→

X

F
S

m_X:X \to X_{FS}

onto a finitely Suslinian quotient such that any monotone map of

X
X

onto a finitely Suslinian quotient factors through

m
X

m_X

. We call the pair

(

X

F
S

,

m
X

)

(X_{FS},m_X)

(or, more loosely,

X

F
S

X_{FS}

) the finest finitely Suslinian model of

X
X

.

If

f
:

C

→

C

f:\mathbb {C}\to \mathbb {C}

is a branched covering map and

X
⊂

C

X \subset \mathbb {C}

is a fully invariant compactum, then the appropriate extension

M
X

M_X

of

m
X

m_X

monotonically semiconjugates

f
f

to a branched covering map

g
:

C

→

C

g:\mathbb {C}\to \mathbb {C}

which serves as a model for

f
f

. If

f
f

is a polynomial and

J
f

J_f

is its Julia set, we show that

m
X

m_X

(or

M
X

M_X

) can be defined on each component

Z
Z

of

J
f

J_f

individually as the finest monotone map of

Z
Z

onto a locally connected continuum.
Rab1b overexpression modifies Golgi size and gene expression in HeLa cells and modulates the thyrotrophin response in thyroid cells in culture
Authors: Romero Nahuel , Dumur Catherine I. , Martinez Hernán , García Iris A. , Monetta Pablo , Slavin Ileana , Sampieri Luciana , Koritschoner Nicolas , Mironov Alexander A. , De Matteis Maria Antonietta , Alvarez Cecilia
Published: January 2013

Rab1b belongs to the Rab-GTPase family that regulates membrane trafficking and signal transduction systems able to control diverse cellular activities, including gene expression. Rab1b is essential for endoplasmic reticulum–Golgi transport. Although it is ubiquitously expressed, its mRNA levels vary among different tissues. This work aims to characterize the role of the high Rab1b levels detected in some secretory tissues. We report that, in HeLa cells, an increase in Rab1b levels induces changes in Golgi size and gene expression. Significantly, analyses applied to selected genes, KDELR3, GM130 (involved in membrane transport), and the proto-oncogene JUN, indicate that the Rab1b increase acts as a molecular switch to control the expression of these genes at the transcriptional level, resulting in changes at the protein level. These Rab1b-dependent changes require the activity of p38 mitogen-activated protein kinase and the cAMP-responsive element-binding protein consensus binding site in those target promoter regions. Moreover, our results reveal that, in a secretory thyroid cell line (FRTL5), Rab1b expression increases in response to thyroid-stimulating hormone (TSH). Additionally, changes in Rab1b expression in FRTL5 cells modify the specific TSH response. Our results show, for the first time, that changes in Rab1b levels modulate gene transcription and strongly suggest that a Rab1b increase is required to elicit a secretory response.
Serum 25‐hydroxyvitamin D and left ventricular systolic function in a non‐smoking population: the Tromsø Study
Authors: Kamycheva Elena , Wilsgaard Tom , Schirmer Henrik , Jorde Rolf
Published: January 2013

Aims

The myocardium is considered to be an important target organ for parathyroid hormone and 1,25‐dihydroxyvitamin D, the active metabolite of vitamin D. Vitamin D inadequacy has also been linked to cardiovascular morbidity. We aimed to evaluate the relationship between serum 25‐hydroxyvitamin D [25(OH)D] and LV systolic function in a general population.

Methods and results

In the fourth Tromsø Study, M‐mode echocardiography was performed in 2504 subjects with available serum 25(OH)D measurements. Measurements of EF and LV mass indexed by height (LVMH) were obtained. Only non‐smoking men (n = 790) and women (n = 944) were included in the final analysis. Linear regression was used to assess the association between serum 25(OH)D and measurements of systolic function, and logistic regression was applied to assess the effect of serum 25(OH)D on the lowest quartile of EF (yes/no) and LV hypertrophy (LVH) (yes/no). We found no significant associations between vitamin D concentrations and measures of LV systolic function, when adjusted for other risk factors and the season when 25(OH)D sampling was performed [β –0.03, 95% confidence interval (CI) –0.08 to 0.03, and β –0.01, 95% CI –0.07 to 0.06 for LVMH and EF in men; and β 0.02, 95% CI –0.03 to 0.07, and β 0.01, 95% CI –0.05 to 0.07 for LVMH and EF in women]. Serum 25(OH)D did not predict EF and/or LVH in both genders.

Conclusions

In our population‐based study, increased serum 25(OH)D was not associated with better LV systolic function, when adjusted for other risk factors and for season of vitamin D sampling.