bluuebunny/crossref_metadata_2025 huggingface dataset:
Motivation und Selbstreguliertes Lernen in SchülerInnengruppen mit unterschiedlicher Aggressionserfahrung
Authors: Bergsmann Evelyn Maria , Finsterwald Monika , Strohmeier Dagmar , Spiel Christiane
Published: May 2011

Zusammenfassung. Die vorliegende Studie beschäftigte sich in einem personenzentrierten Ansatz mit der Beziehung zwischen Täter-Opfer-Verhalten und Lernvariablen. Untersucht wurden Jugendliche, die stabil (über zwei Messzeitpunkte hinweg) als Täterinnen bzw. Täter, Opfer, Täter-Opfer und Unbeteiligte identifiziert werden konnten. Diese vier stabilen Gruppen wurden in der Geschlechterverteilung sowie in schulischer Motivation (Interesse und Selbstwirksamkeit) und im Selbstregulierten Lernen verglichen. Die Ausgangsstichprobe bestand aus 956 Schülerinnen und Schülern der sechsten und siebten Schulstufe, die zu zwei Messzeitpunkten einen Fragebogen zum Thema Aggression in der Schule beantworteten. 478 Jugendliche blieben in ihrer Gruppenzugehörigkeit stabil und wurden daher in die Studie aufgenommen. Zur Prüfung der Geschlechterverteilung wurde eine Konfigurationsfrequenzanalyse durchgeführt, die zeigte, dass sich unter den stabilen Unbeteiligten signifikant mehr Mädchen und unter den stabilen Täter-Opfern signifikant mehr Buben befinden. Der Gruppenvergleich bzgl. schulischer Motivation und Selbstreguliertem Lernen zeigte, dass insbesondere stabile Täterinnen Risikogruppen bezogen auf die untersuchten Lernvariablen darstellen, nicht jedoch stabile Opfer.
Structural restoration of thrusts at the toe of the Nankai Trough accretionary prism off Shikoku Island, Japan: Implications for dewatering processes
Authors: Moore Gregory F. , Saffer Demian , Studer Melody , Costa Pisani Patrizia
Published: May 2011

A three‐dimensional prestack depth‐migrated seismic reflection data volume acquired off Shikoku Island, Japan covers the seaward portion of the Nankai Trough accretionary prism. We calculate and interpret total horizontal shortening lengths along three cross‐sectional profiles through the volume, incorporating a technique addressing the significant amount of water volume sediments lose during accretion, constrained by porosity values derived from seismic interval velocities. The results reveal a total horizontal shortening of ∼40% within sediments of the first three thrust sheets in the wedge. This indicates that structural restorations applied to water‐saturated young sediments, or other domains displaying large tectonic‐induced porosity changes (e.g., accretionary prisms, subaerial and submarine fold and thrust belts), must account for the substantial amount of distributed compactive strain that affects the sediment during the initial stages of accretion. Our analysis of the porosity reduction also allows an estimate of dewatering rates across the outer accretionary wedge. We find that porosity loss and associated dewatering decrease with distance landward from the trench and correspond to a progressively decreasing contribution of diffuse compactive strain to the total shortening. We compute a dewatering rate of 10.5 km3/Ma (per km along strike) over the outer ∼7 km of the accretionary wedge. This relatively high rate of dewatering when compared to other well‐studied subduction systems probably reflects the large thickness of accreted sediment and high sediment permeability that allows efficient consolidation. These results highlight the importance of considering distributed compactive strain in structural restorations for any setting where deformation occurs in sediments.
Residence time distributions in surface transient storage zones in streams: Estimation via signal deconvolution
Authors: Gooseff Michael N. , Benson David A. , Briggs Martin A. , Weaver Mitchell , Wollheim Wilfred , Peterson Bruce , Hopkinson Charles S.
Published: May 2011

Little is known about the impact of surface transient storage (STS) zones on reach‐scale transport and the fate of dissolved nutrients in streams. Exchange with these locations may influence the rates of nutrient cycling often observed in whole‐stream tracer experiments, particularly because they are sites of organic matter collection and lower flow velocities than those observed in the thalweg. We performed a conservative stream tracer experiment (slug of dissolved NaCl) in the Ipswich River in northeastern Massachusetts and collected solute tracer data both in the thalweg and adjacent STS zones at three locations in a fifth‐order reach. Tracer time series observed in STS zones are an aggregate of residence time distributions (RTDs) of the upstream transport to that point (RTDTHAL) and that of the temporary storage within these zones (RTDSTS). Here we demonstrate the separation of these two RTDs to determine the RTDSTS specifically. Total residence times for these individual STS zones range from 4.5 to 7.5 h, suggesting that these zones have the potential to host important biogeochemical transformations in stream systems. All of the RTDSTS show substantial deviations from the ideal prescribed by the two‐state (mobile/immobile) mass transfer equations. The deviations indicate a model mismatch and that parameter estimation based on the mass transfer equations will yield misleading values.
Spatiotemporal scaling of hydrological and agrochemical export dynamics in a tile‐drained Midwestern watershed
Authors: Guan K. , Thompson S. E. , Harman C. J. , Basu N. B. , Rao P. S. C. , Sivapalan M. , Packman A. I. , Kalita P. K.
Published: May 2011

Conceptualizing catchments as physicochemical filters is an appealing way to link streamflow discharge and concentration time series to hydrological and biogeochemical processing in hillslopes and drainage networks. Making these links explicit is challenging in complex watersheds but may be possible in highly modified catchments where hydrological and biogeochemical processes are simplified. Linking hydrological and biogeochemical filtering in highly modified watersheds is appealing from a water quality perspective in order to identify the major controls on chemical export at different spatial and temporal scales. This study investigates filtering using a 10 year data set of hydrological and biogeochemical export from a small (<500 km2) agricultural watershed in Illinois, the Little Vermilion River (LVR) Watershed. A number of distinct scaling regimes were identified in the Fourier power spectrum of discharge and nitrate, phosphate, and atrazine concentrations. These scaling regimes were related to different runoff pathways and spatial scales throughout the catchment (surface drainage, tile drains, and channel flow in the river). Wavelet analysis indicated increased coupling between discharge and in‐stream concentrations at seasonal‐annual time scales. Using a multiresolution analysis, nitrate, phosphate, and atrazine loads exported at annual scales were found to exhibit near‐linear scaling with annual streamflow, suggesting that at these scales the export dynamics could be approximated as chemostatic responses. This behavior was pronounced for nitrate and less so for phosphate and atrazine. The analysis suggests that biogeochemical inputs built up legacy loads, leading to the emergence of chemostatic behavior at annual time scales, even at the relatively small scale of the LVR.
Determination of the friction law parameters of the Mw 6.7 Michilla earthquake in northern Chile by dynamic inversion
Authors: Ruiz Sergio , Madariaga Raul
Published: May 2011

We perform a full dynamic inversion at low frequencies of the 16 December 2007 (Mw = 6.7) northern Chile earthquake that we model as a simple elliptical patch. We use two different stress‐friction end‐member models: asperities and barriers, finding similar results. The inversions are performed for strong motion data filtered between 0.02 and 0.5 Hz. Eleven geometrical and stress and friction parameters are inverted using the neighbourhood algorithm. The optimum solutions have relative errors lower than 0.21. The earthquake rupture has duration of less than 5 s and propagates at sub‐shear speed. The rupture area is similar to that of the aftershock distribution and the seismic moment is 0.95 · 1019 Nm. We derive the friction law parameters from the models situated close to the optimum solution using a Monte Carlo technique. The results show a strong trade‐off between applied stress and frictional resistance. We find that the distribution of friction models collapses into a finite zone of the space of moment and non‐dimensional parameter κ. We conclude that it is possible to determine the friction law from near field seismograms, but there is a strong trade‐off between friction and initial stress.
Electrical properties of polycrystalline methane hydrate
Authors: Du Frane Wyatt L. , Stern Laura A. , Weitemeyer Karen A. , Constable Steven , Pinkston John C. , Roberts Jeffery J.
Published: May 2011

Electromagnetic (EM) remote‐sensing techniques are demonstrated to be sensitive to gas hydrate concentration and distribution and complement other resource assessment techniques, particularly seismic methods. To fully utilize EM results requires knowledge of the electrical properties of individual phases and mixing relations, yet little is known about the electrical properties of gas hydrates. We developed a pressure cell to synthesize gas hydrate while simultaneously measuring in situ frequency‐dependent electrical conductivity (σ). Synthesis of methane (CH4) hydrate was verified by thermal monitoring and by post run cryogenic scanning electron microscope imaging. Impedance spectra (20 Hz to 2 MHz) were collected before and after synthesis of polycrystalline CH4 hydrate from polycrystalline ice and used to calculate σ. We determined the σ of CH4 hydrate to be 5 × 10−5 S/m at 0°C with activation energy (Ea) of 30.6 kJ/mol (−15 to 15°C). After dissociation back into ice, σ measurements of samples increased by a factor of ∼4 and Ea increased by ∼50%, similar to the starting ice samples.
A new model for the evolution of La Réunion volcanic complex from complete marine geophysical surveys
Authors: Le Friant Anne , Lebas Elodie , Clément Valentin , Boudon Georges , Deplus Christine , de Voogd Béatrice , Bachèlery Patrick
Published: May 2011

Results from recent marine geophysical surveys offer a new perspective for characterizing the evolution processes of volcanic islands. In 2006, cruises FOREVER and ERODER 1 investigated the submarine flanks and the surrounding abyssal plain of La Réunion (Indian Ocean) to obtain for the first time a complete geophysical survey of the area. Combined analyses of these data reveal major differences in the evolution of the two emerged volcanoes, Piton des Neiges and Piton de la Fournaise. We show that debris avalanche deposits extend on the abyssal plain only offshore the active Piton de la Fournaise volcano attesting the occurrence of large flank‐collapse events. The absence of such deposits offshore Piton des Neiges and the presence of compressive structures within the sedimentary unit below the edifice support a mechanism of slow deformation of this volcano, such as sliding or spreading. The slow deformation of Piton des Neiges has led to numerous secondary submarine slope instabilities and favored some unconfined turbidity flows which generated large sediment waves running downward all around the island. This study proposes a new model using the most complete marine data set available: slow deformation controls the evolution of Piton des Neiges whereas Piton de la Fournaise (formed on the flanks of a pre‐existing edifice) experienced catastrophic, large flank‐collapse events.
Tumour suppressor SIRT3 deacetylates and activates manganese superoxide dismutase to scavenge ROS
Authors: Chen Yaohui , Zhang Jinye , Lin Yan , Lei Qunying , Guan Kun‐Liang , Zhao Shimin , Xiong Yue
Published: May 2011

Mitochondria manganese superoxide dismutase (SOD2) is an important antioxidant enzyme, deficiency of which is associated with various human diseases. The known primary regulation of SOD2 is through transcriptional activation. Here, we report that SOD2 is acetylated at Lys 68 and that this acetylation decreases SOD2 activity. Mitochondrial deacetylase SIRT3 binds to, deacetylates and activates SOD2. Increase of reactive oxygen species (ROS) levels stimulates SIRT3 transcription, leading to SOD2 deacetylation and activation. SOD2‐mediated ROS reduction is synergistically increased by SIRT3 co‐expression, but is cancelled by SIRT3 depletion. These results reveal a new post‐translational regulation of SOD2 by means of acetylation and SIRT3‐dependent deacetylation in response to oxidative stress.
c‐di‐AMP reports DNA integrity during sporulation in Bacillus subtilis
Authors: Oppenheimer‐Shaanan Yaara , Wexselblatt Ezequiel , Katzhendler Jehoshua , Yavin Eylon , Ben‐Yehuda Sigal
Published: May 2011

The bacterium Bacillus subtilis produces the DNA integrity scanning protein (DisA), a checkpoint protein that delays sporulation in response to DNA damage. DisA scans the chromosome and pauses at sites of DNA lesions. Structural analysis showed that DisA synthesizes the small molecule cyclic diadenosine monophosphate (c‐di‐AMP). Here, we demonstrate that the intracellular concentration of c‐di‐AMP rises markedly at the onset of sporulation in a DisA‐dependent manner. Furthermore, exposing sporulating cells to DNA‐damaging agents leads to a global decrease in the level of this molecule. This drop was associated with stalled DisA complexes that halt c‐di‐AMP production and with increased levels of the c‐di‐AMP‐degrading enzyme YybT. Reduced c‐di‐AMP levels cause a delay in sporulation that can be reversed by external supplementation of the molecule. Thus, c‐di‐AMP acts as a secondary messenger, coupling DNA integrity with progression of sporulation.
Exorcising ghostwriting…
Authors: Bosch Xavier
Published: May 2011

Ghostwriting violates the ethical standards of scientific research and publishing and can be dangerous to the public where medicine is concerned. Journals, funders and research organizations must adopt stricter procedures for ‘ghostbusting’.
The nature of intestinal stem cells' nurture
Authors: Roth Sabrina , Fodde Riccardo
Published: May 2011

Mustata et al demonstrate in this issue of EMBO reports that Lgr4 expression in the stem cells and transit amplifying cells of the intestinal crypts is required for the establishment of the stem cell niche and also for the maintenance of intestinal stem cells in ex vivo organoid cultures.
Consequences of suboptimal priming are apparent for low‐avidity T‐cell responses
Authors: Venturi Vanessa , Davenport Miles P , Swan Natasha G , Doherty Peter C , Kedzierska Katherine
Published: May 2011

The emergence of the novel reassortant A(H1N1)‐2009 influenza virus highlighted the threat to the global population posed by an influenza pandemic. Pre‐existing CD8+ T‐cell immunity targeting conserved epitopes provides immune protection against newly emerging strains of influenza virus, when minimal antibody immunity exists. However, the occurrence of mutations within T‐cell antigenic peptides that enable the virus to evade T‐cell recognition constitutes a substantial issue for virus control and vaccine design. Recent evidence suggests that it might be feasible to elicit CD8+ T‐cell memory pools to common virus mutants by pre‐emptive vaccination. However, there is a need for a greater understanding of CD8+ T‐cell immunity towards commonly emerging mutants. The present analysis focuses on novel and immunodominant, although of low pMHC‐I avidity, CD8+ T‐cell responses directed at the mutant influenza DbNP366 epitope, DbNPM6A, following different routes of infection. We used a C57BL/6J model of influenza to dissect the effectiveness of the natural intranasal (i.n.) versus intraperitoneal (i.p.) priming for generating functional CD8+ T cells towards the DbNPM6A epitope. In contrast to comparable CD8+ T‐cell responses directed at the wild‐type epitopes, DbNP366 and DbPA224, we found that the priming route greatly affected the numbers, cytokine profiles and TCR repertoire of the responding CD8+ T cells directed at the DbNPM6A viral mutant. As the magnitude, polyfunctionality, and T‐cell repertoire diversity are potential determinants of the protective efficacy of CD8+ T‐cell responses, our data have implications for the development of vaccines to combat virus mutants.
Can ABC be Used for Model Selection?
Authors: Didelot Xavier , Everitt Rich , Johansen Adam , Lawson Dan
Published: May 2011

Over the past ten years, Approximate Bayesian Computation (ABC) has become hugely popular to estimate the parameters of a model when the likelihood function cannot be computed in a reasonable amount of time. ABC can in principle be used also to perform Bayesian model comparison, but this raises the question of which summary statistic should be used for such applications. Here we present a general method for constructing a summary statistic that is sufficient for the model choice problem. We apply this construction to models from the exponential family. Unfortunately, in more complex models, our construct often results in statistics with too high dimensionality to use in ABC. We therefore discuss the possibility of applying ABC with non-sufficient statistics.
Clioquinol induces cytoplasmic clearance of the X-linked inhibitor of apoptosis protein (XIAP): therapeutic indication for prostate cancer
Authors: Cater Michael A. , Haupt Ygal
Published: May 2011

Clioquinol (5-chloro-7-iodo-8-quinolinol) is a copper ionophore that was used primarily during the 1950–1970s as an oral antimicrobial agent. It has been established that clioquinol displays toxicity towards malignant cells, inducing caspase-dependent apoptosis. In the present study we therefore investigated the effect of clioquinol on the XIAP [X-linked IAP (inhibitor of apoptosis protein)], as one of its primary functions is to hinder caspase activity and suppress apoptotic cell death. Clioquinol treatment caused cytoplasmic XIAP to rapidly relocate to the nucleus in multiple human transformed (hyperplasic and carcinoma) prostate lines. Clioquinol also caused the cytoplasmic clearance of other IAP family members (cIAP1 and cIAP2). Copper, and no other relevant bivalent metal (e.g. zinc or iron), was exclusively required for clioquinol to elicit an effect on XIAP. We further demonstrated that clioquinol selectively targets and rapidly destroys transformed prostate lines without harming primary prostate epithelial cells. The toxicity of clioquinol was copper-dependent, positively correlated with the level of extracellular copper and could be abrogated by using the copper chelator TTM (tetrathiomolybdate). Clioquinol forced the profound accumulation of intracellular copper with ensuing toxicity influenced by key regulators of cellular copper homoeostasis. Taken together, our results provide significant insight into clioquinol toxicity and reveal an exciting therapeutic approach for the treatment of prostate cancer.
Reversible membrane reorganizations during photosynthesis in vivo: revealed by small-angle neutron scattering
Authors: Nagy Gergely , Posselt Dorthe , Kovács László , Holm Jens K. , Szabó Milán , Ughy Bettina , Rosta László , Peters Judith , Timmins Peter , Garab Győző
Published: May 2011

In the present study, we determined characteristic repeat distances of the photosynthetic membranes in living cyanobacterial and eukaryotic algal cells, and in intact thylakoid membranes isolated from higher plants with time-resolved small-angle neutron scattering. This non-invasive technique reveals light-induced reversible reorganizations in the seconds-to-minutes time scale, which appear to be associated with functional changes in vivo.
Substrate binding disrupts dimerization and induces nucleotide exchange of the chloroplast GTPase Toc33
Authors: Oreb Mislav , Höfle Anja , Koenig Patrick , Sommer Maik S. , Sinning Irmgard , Wang Fei , Tews Ivo , Schnell Danny J. , Schleiff Enrico
Published: May 2011

GTPases act as molecular switches to control many cellular processes, including signalling, protein translation and targeting. Switch activity can be regulated by external effector proteins or intrinsic properties, such as dimerization. The recognition and translocation of pre-proteins into chloroplasts [via the TOC/TIC (translocator at the outer envelope membrane of chloroplasts/inner envelope membrane of chloroplasts)] is controlled by two homologous receptor GTPases, Toc33 and Toc159, whose reversible dimerization is proposed to regulate translocation of incoming proteins in a GTP-dependent manner. Toc33 is a homodimerizing GTPase. Functional analysis suggests that homodimerization is a key step in the translocation process, the molecular functions of which, as well as the elements regulating this event, are largely unknown. In the present study, we show that homodimerization reduces the rate of nucleotide exchange, which is consistent with the observed orientation of the monomers in the crystal structure. Pre-protein binding induces a dissociation of the Toc33 homodimer and results in the exchange of GDP for GTP. Thus homodimerization does not serve to activate the GTPase activity as discussed many times previously, but to control the nucleotide-loading state. We discuss this novel regulatory mode and its impact on the current models of protein import into the chloroplast.
The Importance of Accurate, Early Bony Reconstruction in Orbital Injuries with Globe Loss
Authors: Birgfeld Craig , Gruss Joseph
Published: May 2011

Patients who sustain facial fractures frequently suffer from visual disturbance. Additionally, orbital fractures often involve ocular injury, which, not infrequently, may require enucleation. Yet an anophthalmic orbit does not obviate the need for aggressive orbital fracture treatment. In fact, treatment of the sequelae of the anophthalmic orbit can be difficult and require multiple surgeries. Intraoperative use of a conformer after accurate bony reduction and orbital reconstruction with bone grafts or orbital implants are essential steps to allow for prosthetic rehabilitation of the anophthalmic orbit.
High speed heterodyne infrared thermography applied to thermal diffusivity identification
Authors: Pradere C. , Clerjaud L. , Batsale J. C. , Dilhaire S.
Published: May 2011

We have combined InfraRed thermography and thermal wave techniques to perform microscale, ultrafast (microsecond) temperature field measurements. The method is based on an IR camera coupled to a microscope and synchronized to the heat source by means of phase locked function generators. The principle is based on electronic stroboscopic sampling where the low IR camera acquisition frequency facq (25 Hz) undersamples a high frequency thermal wave. This technique permits the measurement of the emissive thermal response at a (microsecond) short time scale (microsecond) with the full frame mode of the IR camera with a spatial thermal resolution of 7 μm. Then it becomes possible to study 3D transient heat transfer in heterogeneous and high thermal conductive thin layers. Thus it is possible for the first time in our knowledge to achieve temperature field measurements in heterogeneous media within a wide range of time domains. The IR camera is now a suitable instrument for multiscale thermal analysis.
Mechanism for THz generation from InN micropyramid emitters
Authors: Xu Guibao , Sun Guan , Ding Yujie J. , Zotova Ioulia B. , Jamil Muhammad , Ferguson Ian T.
Published: May 2011

We have investigated characteristics of THz waves generated by using a regenerative amplifier in InN micropyramids. Our experimental results indicate that when the density of the micropyramids becomes sufficiently high, the THz output power is dramatically enhanced. In comparison, the PL intensity stays more or less a constant regardless of the density. By measuring the dependences of the THz output power and polarization on the incident angle and pump polarization angle, we have deduced the contributions to the THz output powers from optical rectification and photocurrent surge.
Note: Development of a high resolution six-degrees-of-freedom optical vibrometer for precision stage
Authors: Hsieh Tung Hsien , Jywe Wen Yuh , Chen Shang Liang , Liu Chien Hung , Huang Hsueh Liang
Published: May 2011

A high resolution six degrees of freedom (6-DOF) optical vibrometer is proposed. 6-DOF vibrations can be simultaneously measured using the proposed optical vibrometer, which reduces measurement time and number. The performance of the proposed vibrometer is verified by experiments. The results show that the accuracy of the proposed optical vibrometer is ±30 nm/200 nm and ±0.04 arcsec/0.1 arcsec at 1000 Hz.
Enhancement of light absorption using high-k dielectric in localized surface plasmon resonance for silicon-based thin film solar cells
Authors: Li Hua-Min , Zhang Gang , Yang Cheng , Lee Dae-Yeong , Lim Yeong-Dae , Shen Tian-Zi , Yoo Won Jong , Park Young Jun , Kim Hyunjin , Nam Cha Seung , Kim Jong Min
Published: May 2011

The application of high-dielectric-constant (k) materials, e.g., Si3N4, ZrO2, and HfO2, to localized surface plasmon resonance (LSPR) excited by a Au nanoparticle structure has been investigated and simulated for the enhancement of light absorption in Si-based thin film solar cells by using Mie theory and three-dimensional finite-difference time-domain computational simulations. As compared to a conventional SiO2 dielectric spacing layer, the high-k dielectrics have significant advantages, such as (i) a polarizability over two times higher, (ii) an extinction cross-section 4.1 times larger, (iii) a 5.6% higher transmission coefficient, (iv) a maximal 39.9% and average 25.0% increase in the transmission of the electromagnetic field, (v) an absorption of the transmitted electromagnetic field that is a maximum of 2.8 times and an average of 1.4 times greater, and (vi) increased absorption efficiency and extended cover range. Experimental results show that the average absorptance in the visible spectrum using high-k enhanced LSPR was maximally 31.1% higher than that using SiO2, demonstrating that the high-k dielectrics can be used as a potential spacing layer for light absorption in Au nanoparticle excited LSPR in Si-based thin film solar cells.
Measurement of the refractive index dispersion of As2Se3 bulk glass and thin films prior to and after laser irradiation and annealing using prism coupling in the near- and mid-infrared spectral range
Authors: Carlie N. , Anheier N. C. , Qiao H. A. , Bernacki B. , Phillips M. C. , Petit L. , Musgraves J. D. , Richardson K.
Published: May 2011

The prism coupling technique has been utilized to measure the refractive index in the near- and mid-IR spectral region of chalcogenide glasses in bulk and thin film form. A commercial system (Metricon model 2010) has been modified with additional laser sources, detectors, and a new GaP prism to allow the measurement of refractive index dispersion over the 1.5–10.6 μm range. The instrumental error was found to be ±0.001 refractive index units across the entire wavelength region examined. Measurements on thermally evaporated AMTIR2 thin films confirmed that (i) the film deposition process provides thin films with reduced index compared to that of the bulk glass used as a target, (ii) annealing of the films increases the refractive index of the film to the level of the bulk glass used as a target to create it, and (iii) it is possible to locally increase the refractive index of the chalcogenide glass using laser exposure at 632.8 nm.
Interlayer couplings in a differential dual spin valve
Authors: Han G. C. , Wang C. C. , Qiu J. J. , Luo P. , Ko V.
Published: May 2011

As a differential dual spin valve (DDSV) consists of two SVs separated by a gap layer, in addition to the interlayer couplings between the free layer (FL) and its reference layer in each SV, it is important to understand the interaction between the two FLs and its effect on reading performances. Systematical studies on FL’s switching behavior have been performed in both thin films and small devices. For thin-film samples, FL’s switching is governed by interlayer couplings while for a patterned DDSV device it is dominated by the strong magnetostatic edge coupling of the two FLs.
Superoleophobicity under vacuum
Authors: Liu Xinjie , Wang Xiaolong , Liang Yongmin , Bell Steven E. J. , Liu Weimin , Zhou Feng
Published: May 2011

By using superoleophobic alumina and low vapor pressure oils we have been able to study wetting behavior at high vacuum. Here, we show that a superoleophobic state can exist for some probe liquids, even under high vacuum. However, with other liquids the surfaces are only superoloephobic because air is trapped beneath the droplet and the contact angle decreases dramatically (150°–120°) if this air is removed. These observations open up the possibility of designing materials which fully exploit the potential of physically trapped air to achieve extreme oleophobicity and/or hydrophobicity.
Martensite transformation of epitaxial Ni–Ti films
Authors: Buschbeck J. , Kawasaki J. K. , Kozhanov A. , James R. D. , Palmstrøm C. J.
Published: May 2011

The structure and phase transformations of thin Ni–Ti shape memory alloy films grown by molecular beam epitaxy are investigated for compositions from 43 to 56 at. % Ti. Despite the substrate constraint, temperature dependent x-ray diffraction and resistivity measurements reveal reversible, martensitic phase transformations. The results suggest that these occur by an in-plane shear which does not disturb the lattice coherence at interfaces.
Energy efficient microcavity lasers with 20 and 40 Gb/s data transmission
Authors: Tan F. , Wu C. H. , Feng M. , Holonyak N.
Published: May 2011

Microcavity lasers (μCLs), reduced-size (≲3 μm aperture) vertical cavity surface-emitting lasers (VCSELs) defined by the buried-oxide process for current and field confinement (thus wide mode spacing), are demonstrated with low threshold current, sharp turn-on L-I characteristics, and wide bandwidth operation. Due to the enhanced spontaneous recombination rate at reduced mode and improved photon density, μCLs exhibit lower charge-field resonance peaks at a modulation bandwidth f−3 dB=18.7 GHz, thus permitting open-“eye” operation at 20 and 40 Gb/s data rates (I≲3 mA). The energy efficiency for 20 Gb/s data transmission is measured to be 4.84 Gb/s/mW, which is eight times better than 7 μm aperture VCSELs.
Single-step direct measurement of amyloid fibrils stiffness by peak force quantitative nanomechanical atomic force microscopy
Authors: Adamcik Jozef , Berquand Alexandre , Mezzenga Raffaele
Published: May 2011

We present an original application of a new atomic force microscopy mode called peak force tapping for the investigation of the mechanical properties of β-lactoglobulin amyloid fibrils. The values of Young’s modulus obtained by this technique are in perfect agreement with the indirect evaluation of fibrils stiffness obtained by combining polymer physics and topological statistical analysis on fibrils’ structural conformations. This technique shows great promise in the estimation of the elastic properties of nanostructured objects relevant in biology, soft matter, and nanotechnology.
Single-electron counting statistics of shot noise in nanowire Si metal-oxide-semiconductor field-effect transistors
Authors: Nishiguchi Katsuhiko , Ono Yukinori , Fujiwara Akira
Published: May 2011

Shot noise in the transport of single electrons in a Si metal-oxide-semiconductor field-effect transistor is monitored by real-time measurement with a high-charge-sensitivity electrometer. In the current range between zepto and attoamperes, the current characteristics are found to be divided into two regimes: a temperature-independent regime in the lower current range and a temperature-dependent one in the higher current range. A time-domain analysis reveals that, for both regimes, the single-electron transport obeys a pure Poisson process with the Fano factor’s being nearly unity, while the shot noise is suppressed with reduced Fano factors around the boundary.
Copper oxide transistor on copper wire for e-textile
Authors: Han Jin-Woo , Meyyappan M.
Published: May 2011

A Cu2O-based field effect transistor was fabricated on Cu wire. Thermal oxidation of Cu forms Cu–Cu2O core-shell structure, where the metal-semiconductor Schottky junction was used as a gate barrier with Pt Ohmic contacts for source and drain. The device was coated with polydimethylsiloxane (PDMS) to protect from contamination and demonstrated as a humidity sensor. The cylindrical structure of the Cu wire and the transistor function enable embedding of simple circuits into textile which can potentially offer smart textile for wearable computing, environmental sensing, and monitoring of human vital signs.
Religion versus ethnicity as predictors of unprotected vaginal intercourse among young adults
Authors: James Carolyn A. , Hart Trevor A. , Roberts Karen E. , Ghai Amrita , Petrovic Bojana , Lima Michael D.
Published: May 2011

Background
Young adults in North America are at increasing risk for contracting HIV and sexually transmissible infections (STI). Racial differences in HIV or STI risk are well documented, but other cultural and demographic factors contributing to HIV or STI risk are poorly understood. Although religion may play an important role in sexual behaviour, little research has explored its association with sexual attitudes, beliefs and practices. The present study examined how ethnicity, religion, HIV knowledge and attitudes, and other demographic factors are associated with engaging in unprotected vaginal intercourse (UVI) in a diverse sample of unmarried young adults. Methods: A cross-sectional study of 666 unmarried university students was conducted from 2005 to 2007, with participants completing an anonymous questionnaire on sexual attitudes and health for course credit. Results: Approximately 50% of the respondents had engaged in any vaginal intercourse and 32.2% had engaged in UVI in the past 6 months. Multivariable analyses showed that increasing age, being in a relationship for more than 6 months, greater HIV knowledge, stronger attitudes supporting the use of condoms, and religion (but not ethnicity) were associated with engaging in UVI. Among the sexually active subset of the sample (n = 332), religion was the only predictor of engaging in UVI. Conclusion: Ethnicity, which is often considered an important variable in sexual health research, does not appear to be associated with UVI when taking into account other demographic variables, particularly religion. Consideration of religion may be important in devising HIV prevention interventions, in order to implement them in accordance with particular religious beliefs.
Enteric commensal bacteria potentiate epithelial restitution via reactive oxygen species-mediated inactivation of focal adhesion kinase phosphatases
Authors: Swanson Phillip A. , Kumar Amrita , Samarin Stanislav , Vijay-Kumar Matam , Kundu Kousik , Murthy Niren , Hansen Jason , Nusrat Asma , Neish Andrew S.
Published: May 2011

The mechanisms by which enteric commensal microbiota influence maturation and repair of the epithelial barrier are relatively unknown. Epithelial restitution requires active cell migration, a process dependent on dynamic turnover of focal cell-matrix adhesions (FAs). Here, we demonstrate that natural, commensal bacteria stimulate generation of reactive oxygen species (ROS) in intestinal epithelia. Bacteria-mediated ROS generation induces oxidation of target cysteines in the redox-sensitive tyrosine phosphatases, LMW-PTP and SHP-2, which in turn results in increased phosphorylation of focal adhesion kinase (FAK), a key protein regulating the turnover of FAs. Accordingly, phosphorylation of FAK substrate proteins, focal adhesion formation, and cell migration are all significantly enhanced by bacterial contact in both in vitro and in vivo models of wound closure. These results suggest that commensal bacteria regulate cell migration via induced generation of ROS in epithelial cells.
Solar composition from the Genesis Discovery Mission
Authors: Burnett D. S. , Team Genesis Science
Published: May 2011

Science results from the Genesis Mission illustrate the major advantages of sample return missions. (
i
) Important results not otherwise obtainable except by analysis in terrestrial laboratories: the isotopic compositions of O, N, and noble gases differ in the Sun from other inner solar system objects. The N isotopic composition is the same as that of Jupiter. Genesis has resolved discrepancies in the noble gas data from solar wind implanted in lunar soils. (
ii
) The most advanced analytical instruments have been applied to Genesis samples, including some developed specifically for the mission. (
iii
) The N isotope result has been replicated with four different instruments.
Variation in individual walking behavior creates the impression of a Lévy flight
Authors: Petrovskii Sergei , Mashanova Alla , Jansen Vincent A. A.
Published: May 2011

Many animal paths have an intricate statistical pattern that manifests itself as a power law-like tail in the distribution of movement lengths. Such distributions occur if individuals move according to a Lévy flight (a mode of dispersal in which the distance moved follows a power law), or if there is variation between individuals such that some individuals move much farther than others. Distinguishing between these two mechanisms requires large quantities of data, which are not available for most species studied. Here, we analyze paths of black bean aphids (
Aphis fabae
Scopoli) and show that individual animals move in a predominantly diffusive manner, but that, because of variation at population level, they collectively appear to display superdiffusive characteristics, often interpreted as being characteristic for a Lévy flight.
Tracking brain states under general anesthesia by using global coherence analysis
Authors: Cimenser Aylin , Purdon Patrick L. , Pierce Eric T. , Walsh John L. , Salazar-Gomez Andres F. , Harrell Priscilla G. , Tavares-Stoeckel Casie , Habeeb Kathleen , Brown Emery N.
Published: May 2011

Time and frequency domain analyses of scalp EEG recordings are widely used to track changes in brain states under general anesthesia. Although these analyses have suggested that different spatial patterns are associated with changes in the state of general anesthesia, the extent to which these patterns are spatially coordinated has not been systematically characterized. Global coherence, the ratio of the largest eigenvalue to the sum of the eigenvalues of the cross-spectral matrix at a given frequency and time, has been used to analyze the spatiotemporal dynamics of multivariate time-series. Using 64-lead EEG recorded from human subjects receiving computer-controlled infusions of the anesthetic propofol, we used surface Laplacian referencing combined with spectral and global coherence analyses to track the spatiotemporal dynamics of the brain's anesthetic state. During unconsciousness the spectrograms in the frontal leads showed increasing α (8–12 Hz) and δ power (0–4 Hz) and in the occipital leads δ power greater than α power. The global coherence detected strong coordinated α activity in the occipital leads in the awake state that shifted to the frontal leads during unconsciousness. It revealed a lack of coordinated δ activity during both the awake and unconscious states. Although strong frontal power during general anesthesia-induced unconsciousness—termed anteriorization—is well known, its possible association with strong α range global coherence suggests highly coordinated spatial activity. Our findings suggest that combined spectral and global coherence analyses may offer a new approach to tracking brain states under general anesthesia.
Binding of α-thrombin to surface-anchored platelet glycoprotein Ibα sulfotyrosines through a two-site mechanism involving exosite I
Authors: Zarpellon Alessandro , Celikel Reha , Roberts James R. , McClintock Richard A. , Mendolicchio G. Loredana , Moore Kevin L. , Jing Hua , Varughese Kottayil I. , Ruggeri Zaverio M.
Published: May 2011

The involvement of exosite I in α-thrombin (FIIa) binding to platelet glycoprotein Ibα (GPIbα), which could influence interactions with other substrates, remains undefined. To address the problem, we generated the GPIbα amino terminal domain (GPIbα-N) fully sulfated on three tyrosine residues and solved the structure of its complex with FIIa. We found that sulfotyrosine (Tys) 278 enhances the interaction mainly by establishing contacts with exosite I. We then evaluated how substituting tyrosine with phenylalanine, which cannot be sulfated, affects FIIa binding to soluble or surface-immobilized GPIbα-N. Mutating Tyr
276
, which mostly contacts exosite II residues, markedly reduced FIIa interaction with both soluble and immobilized GPIbα-N; mutating Tyr
278
or Tyr
279
, which mostly contact exosite I residues, reduced FIIa complexing in solution by 0–20% but affinity for immobilized GPIbα-N 2 to 6-fold, respectively. Moreover, three exosite I ligands—aptamer HD1, hirugen, and lepirudin—did not interfere with soluble FIIa complexing to GPIbα-N, excluding that their binding caused allosteric effects influencing the interaction; nonetheless, all impaired FIIa binding to immobilized GPIbα-N and platelet GPIb nearly as much as aptamer HD22 and heparin, both exosite II ligands. Bound HD1 and hirugen alter Trp
148
orientation in a loop near exosite I preventing contacts with the sulfate oxygen atoms of Tys
279
. These results support a mechanism in which binding occurs when the two exosites of one FIIa molecule independently interact with two immobilized GPIbα molecules. Through exosite engagement, GPIbα may influence FIIa-dependent processes relevant to hemostasis and thrombosis.
Bidirectional autoregulatory mechanism of metastasis-associated protein 1-alternative reading frame pathway in oncogenesis
Authors: Li Da-Qiang , Pakala Suresh B. , Reddy Sirigiri Divijendra Natha , Ohshiro Kazufumi , Zhang Jun-Xiang , Wang Lei , Zhang Yanping , Moreno de Alborán Ignacio , Pillai M. Radhakrishna , Eswaran Jeyanthy , Kumar Rakesh
Published: May 2011

Although metastasis-associated protein 1 (MTA1), a component of the nucleosome remodeling and histone deacetylation complex, is widely up-regulated in human cancers and correlates with tumor metastasis, its regulatory mechanism and related signaling pathways remain unknown. Here, we report a previously unrecognized bidirectional autoregulatory loop between MTA1 and tumor suppressor alternative reading frame (ARF). MTA1 transactivates
ARF
transcription by recruiting the transcription factor c-Jun onto the
ARF
promoter in a p53-independent manner. ARF, in turn, negatively regulates MTA1 expression independently of p53 and c-Myc. In this context, ARF interacts with transcription factor specificity protein 1 (SP1) and promotes its proteasomal degradation by enhancing its interaction with proteasome subunit regulatory particle ATPase 6, thereby abrogating the ability of SP1 to stimulate
MTA1
transcription. ARF also physically associates with MTA1 and affects its protein stability. Thus, MTA1-mediated activation of
ARF
and ARF-mediated functional inhibition of MTA1 represent a p53-independent bidirectional autoregulatory mechanism in which these two opposites act in concert to regulate cell homeostasis and oncogenesis, depending on the cellular context and the environment.
Object decoding with attention in inferior temporal cortex
Authors: Zhang Ying , Meyers Ethan M. , Bichot Narcisse P. , Serre Thomas , Poggio Tomaso A. , Desimone Robert
Published: May 2011

Recognizing objects in cluttered scenes requires attentional mechanisms to filter out distracting information. Previous studies have found several physiological correlates of attention in visual cortex, including larger responses for attended objects. However, it has been unclear whether these attention-related changes have a large impact on information about objects at the neural population level. To address this question, we trained monkeys to covertly deploy their visual attention from a central fixation point to one of three objects displayed in the periphery, and we decoded information about the identity and position of the objects from populations of ∼200 neurons from the inferior temporal cortex using a pattern classifier. The results show that before attention was deployed, information about the identity and position of each object was greatly reduced relative to when these objects were shown in isolation. However, when a monkey attended to an object, the pattern of neural activity, represented as a vector with dimensionality equal to the size of the neural population, was restored toward the vector representing the isolated object. Despite this nearly exclusive representation of the attended object, an increase in the salience of nonattended objects caused “bottom-up” mechanisms to override these “top-down” attentional enhancements. The method described here can be used to assess which attention-related physiological changes are directly related to object recognition, and should be helpful in assessing the role of additional physiological changes in the future.
B cells within germinal centers migrate preferentially from dark to light zone
Authors: Beltman Joost B. , Allen Christopher D. C. , Cyster Jason G. , de Boer Rob J.
Published: May 2011

One of the main questions in the field of imaging immune cell migration in living tissues is whether cells fulfill their functionality via random or nonrandom migration processes. For some applications, this issue has remained controversial even after publication of various imaging studies. A prime example is B-cell migration in germinal centers (GCs) where somatic hypermutation and clonal selection of B cells are thought to occur within morphologically distinct regions termed dark zone (DZ) and light zone (LZ). Here, we reanalyze a previously published dataset on GC B-cell migration, applying a sensitive analysis technique to detect directed migration and using a procedure to correct for a number of artifacts that frequently occur in time-lapse imaging experiments. Although B cells roughly perform a persistent random walk, we present evidence that they have a small preference (of on average about 0.2−0.3 μm min
−1
) to migrate from DZ to LZ, which is consistent with classical views of the GC reaction. This preference is most pronounced among a large subset of almost half of the B-cell population migrating along relatively straight tracks. Using a computational model to generate long-lasting B-cell tracks based on the experimental motility data (including the small directional preference), we predict a time course to travel from DZ to LZ of a few hours. This is consistent with experimental observations, and we show that at the observed cellular motility such a time course cannot be explained without the small preferential migration from DZ to LZ.
Age-related memory deficits linked to circuit-specific disruptions in the hippocampus
Authors: Yassa Michael A. , Mattfeld Aaron T. , Stark Shauna M. , Stark Craig E. L.
Published: May 2011

Converging data from rodents and humans have demonstrated an age-related decline in pattern separation abilities (the ability to discriminate among similar experiences). Several studies have proposed the dentate and CA3 subfields of the hippocampus as the potential locus of this change. Specifically, these studies identified rigidity in place cell remapping in similar environments in the CA3. We used high-resolution fMRI to examine activity profiles in the dentate gyrus and CA3 in young and older adults as stimulus similarity was incrementally varied. We report evidence for “representational rigidity” in older adults’ dentate/CA3 that is linked to behavioral discrimination deficits. Using ultrahigh-resolution diffusion imaging, we quantified both the integrity of the perforant path as well as dentate/CA3 dendritic changes and found that both were correlated with dentate/CA3 functional rigidity. These results highlight structural and functional alterations in the hippocampal network that predict age-related changes in memory function and present potential targets for intervention.