bluuebunny/crossref_metadata_2025 huggingface dataset:
Energy spectrum of argon ions emitted from Filippov type Sahand plasma focus
Authors: Mohammadnejad M. , Pestehe S. J. , Mohammadi M. A.
Published: July 2013

The energy and flux of the argon ions produced in Sahand plasma focus have been measured by employing a well-designed Faraday cup. The secondary electron emission effects on the ion signals are simulated and the dimensions of Faraday cup are optimized to minimize these effects. The measured ion energy spectrum is corrected for the ion energy loss and charge exchange in the background gas. The effects of the capacitor bank voltage and working gas pressure on the ion energy spectrum are also investigated. It has been shown that the emitted ion number per energy increases as the capacitor bank voltage increases. Decreasing the working gas pressure leads to the increase in the number of emitted ion per energy.
Langmuir probe diagnostics of plasma in high current electron cyclotron resonance proton ion source
Authors: Roychowdhury P. , Kewlani H. , Mishra L. , Patil D. S. , Mittal K. C.
Published: July 2013

A high current Electron Cyclotron Resonance (ECR) proton ion source has been developed for low energy high intensity proton accelerator at Bhabha Atomic Research Centre. Langmuir probe diagnostics of the plasma generated in this proton ion source is performed using Langmuir probe. The diagnostics of plasma in the ion source is important as it determines beam parameters of the ion source, i.e., beam current, emittance, and available species. The plasma parameter measurement in the ion source is performed in continuously working and pulsed mode using hydrogen as plasma generation gas. The measurement is performed in the ECR zone for operating pressure and microwave power range of 10−4–10−3 mbar and 400–1000 W. An automated Langmuir probe diagnostics unit with data acquisition system is developed to measure these parameters. The diagnostics studies indicate that the plasma density and plasma electron temperature measured are in the range 5.6 × 1010 cm−3 to 3.8 × 1011 cm−3 and 4–14 eV, respectively. Using this plasma, ion beam current of tens of mA is extracted. The variations of plasma parameters with microwave power, gas pressure, and radial location of the probe have been studied.
Interpretation of quasielastic scattering spectra of probe species in complex fluids
Authors: Phillies George D. J.
Published: July 2013

The objective of this paper is to correct an error in analyses of quasielastic scattering spectra. The error invokes a valid calculation under conditions in which its primary assumptions are incorrect, which results in misleading interpretations of spectra. Quasielastic scattering from dilute probes yields the incoherent structure factor g(1s)(q, t) = ⟨exp (iqΔx(t))⟩, with q being the magnitude of the scattering vector q and Δx(t) being the probe displacement parallel to q during a time interval t. The error is a claim that g(1s)(q, t) ∼ exp (−q2⟨(Δx(t))2⟩/2) for probes in an arbitrary solution, leading to the incorrect belief that ⟨(Δx(t))2⟩ of probes in complex fluids can be inferred from quasielastic scattering. The actual theoretical result refers only to monodisperse probes in simple Newtonian liquids. In general, g(1s)(q, t) is determined by all even moments ⟨(Δx(t))2n⟩, n = 1, 2, 3, … of the displacement distribution function P(Δx, t). Correspondingly, ⟨(Δx(t))2⟩ cannot in general be inferred from g(1s) (q, t). The theoretical model that ties g(1s)(q, t) to ⟨(Δx(t))2⟩ also quantitatively determines exactly how ⟨(Δx(t))2⟩/2) must behave, namely, ⟨(Δx(t))2⟩ must increase linearly with t. If the spectrum is not a single exponential in time, g(1s)(q, t) does not determine ⟨(Δx(t))2⟩.
Effect of crosslink formation on heat conduction in amorphous polymers
Authors: Kikugawa Gota , Desai Tapan G. , Keblinski Pawel , Ohara Taku
Published: July 2013

We performed molecular dynamics (MD) simulations on amorphous polyethylene (PE) and polystyrene (PS) in order to elucidate the effect of crosslinks between polymer chains on heat conduction. In each polymer system, thermal conductivities were measured for a range of crosslink concentration by using nonequilibrium MD techniques. PE comprised of 50 carbon atom long chains exhibited slightly higher conductivity than that of 250 carbon atom long chains at the standard state. In both cases for PE, crosslinking significantly increased conductivity and the increase was more or less proportional to the crosslink density. On the other hand, in the PS case, although the thermal conductivity increased with the crosslinking, the magnitude of change in thermal conductivity was relatively small. We attribute this difference to highly heterogeneous PS based network including phenyl side groups. In order to elucidate the mechanism for the increase of thermal conductivity with the crosslink concentration, we decomposed energy transfer into modes associated with various bonded and non-bonded interactions.
Efficient spin injection through a crystalline AlOx tunnel barrier prepared by the oxidation of an ultra-thin Al epitaxial layer on GaAs
Authors: Nishizawa N. , Munekata H.
Published: July 2013

We report that an ultra-thin, post-oxidized aluminum epilayer grown on the AlGaAs surface works as a high-quality tunnel barrier for spin injection from a ferromagnetic metal to a semiconductor. One of the key points of the present oxidation method is the formation of the crystalline AlOx template layer without oxidizing the AlGaAs region near the Al/AlGaAs interface. The oxidized Al layer is not amorphous but show well-defined single crystalline feature reminiscent of the spinel γ-AlOx phase. A spin-light emitting diode consisting of a Fe layer, a crystalline AlOx barrier layer, and an AlGaAs-InGaAs double hetero-structure has exhibited circularly polarized electroluminescence with circular polarization of PEL ∼ 0.145 at the remnant magnetization state of the Fe layer, indicating the relatively high spin injection efficiency (≡2PEL/PFe) of 0.63.
Preparation and characterization of diamond-like carbon/oxides composite film on carbon steel by cathodic plasma electrolysis
Authors: Wu Jie , Xue Wenbin , Jin Xiaoyue , Wang Bin , Du Jiancheng , Wu Zhenglong
Published: July 2013

We employ cathodic plasma electrolysis method for the preparation of diamond-like carbon (DLC) and iron oxides composite film on T8 high-carbon steel. In our study, a continuous vapor envelope was broken down at a critical voltage, resulting in the plasma discharge at the near-cathode region. Active hydrogen, carbon, and oxygen species, decomposed from glycerol, were absorbed by cathode surface and then interacted to form DLC/oxides composite film. The composite film displays a high wear resistance. This method provides an approach for the fabrication of the DLC composite materials.
Electrowetting pixels with improved transmittance using dye doped liquid crystals
Authors: Wells G. G. , Matranga M. A. , Newton C. J. P , Taphouse T. S. , Baig S. A. , Kitson S. C.
Published: July 2013

Electrowetting display pixels have been created using a dye doped liquid crystal as the dielectric liquid in a simple electrowetting architecture. In addition to electrowetting, the dye doped liquid crystal reorients, giving two mechanisms to modulate the light. We show that realignment of the liquid crystal, due to the electric field, occurs both before and during electrowetting. The transmission of the pixel has been compared to the transmission of a pixel containing an isotropic liquid, using a simple mathematical model, and we show that electrical realignment of the LC improves the transmission of the pixel. We show a 6.8% gain in the transmission during electrowetting, and before electrowetting occurs.
Influence on ferromagnetic resonance signal of perpendicular magnetic anisotropic Co/Pt bilayer thin film due to microwave induced spin-Hall effect
Authors: Ahmad Saood , Shah Jyoti , Puri Nitin K. , Negi P. S. , Kotnala R. K.
Published: July 2013

Microwave induced spin-Hall effect has been investigated in sputtered Co/Pt bilayer thin film for its application in the field of spintronics. Measurements were carried out in the frequency range from 0.1 to 10.0 GHz at 10 mW power level with a sweeping magnetic field up to 0.2 T. The maximum dc voltage measured was 5.78 μV at 0.1 GHz in perpendicular applied magnetic field on the bilayer film. The direction of magnetic field, frequency, and power level influence the ferromagnetic resonance signal. Measurements confirm lower effective spin pumping due to a weak perpendicular anisotropy in the film.
Study on molecular devices with negative differential resistance
Authors: Mahmoud Ahmed , Lugli Paolo
Published: July 2013

This paper provides a first-principles study for the transport behavior of molecular devices exhibiting wide bias range of negative differential resistance (NDR). The devices are composed of a diphenyl-dimethyl connected to carbon chains from each side, which are then linked to gold electrodes through thiol-gold bond. The devices show an odd/even oscillating behavior: the NDR appears only for “odd” numbers of carbon atoms in the chain. We look at different device parameters in order to determine the sources of the NDR behavior. We attribute this behavior to a lack of electrons within the chain in case of “odd” number of carbon atoms.
High-vacuum adhesion and friction properties of sliding contact-mode micromachines
Authors: Xiang H. , Komvopoulos K.
Published: July 2013

The evolution of adhesion and friction in contact-mode micromachines operated in high vacuum was studied by tracking changes in the adhesive pressure, interfacial shear strength, and static coefficient of friction with accumulating sliding cycles. Low adhesion and high static friction observed during the initial stage of sliding were followed by monotonically intensifying adhesion and decreasing friction until reaching an equilibrium stage at steady-state sliding. This trend revealed the existence of two friction regimes in which asperity deformation and adhesion were the dominant friction mechanisms. Scanning electron microscopy and atomic force microscopy observations indicated that sliding resulted in physical and chemical surface changes. The evolution of the adhesion and friction properties with sliding cycles is attributed to the increase of both the real contact area and the work of adhesion due to nanoscale surface smoothening and the removal of contaminant adsorbents, respectively.
Energy level(s) of the dissociation product of the 1.014 eV photoluminescence copper center in n-type silicon determined by photoluminescence and deep-level transient spectroscopy
Authors: Nakamura Minoru , Murakami Susumu , Udono Haruhiko
Published: July 2013

The annealing behavior of copper centers in n-type silicon diffused with dilute copper was measured by photoluminescence (PL) and deep-level transient spectroscopy (DLTS) to investigate the energy level (or levels) of the dissociation product center of the 1.014 eV PL copper center. Among several DLTS peaks that appeared by the annealing, only the energy level at Ec − 0.16 eV (Ec: bottom energy of the conduction band) was suggested as the double acceptor level of the dissociation product center. From the disagreement between the measured energy levels of the dissociation product center and the estimated acceptor levels of substitutional copper (Cus), Cus was judged to be inappropriate for the origin of the product center.
Limiting thermomagnetic avalanches in superconducting films by stop-holes
Authors: Colauto F. , Vestgården J. I. , Andrade A. M. H. de , Oliveira A. A. M. , Ortiz W. A. , Johansen T. H.
Published: July 2013

It is demonstrated that circular holes in superconducting films of Nb can arrest the propagation of thermomagnetic avalanches. The effect was found over a range of temperatures where the material is susceptible to this instability. For other hole shapes, like square and triangular, the sharp corners provoke secondary avalanches, thus extending the breakdown. Making use of circular stop-holes can become a practical way to limit thermomagnetic breakdown in superconducting films.
Electron tunneling through graphene-based double barriers driven by a periodic potential
Authors: Ojeda-Collado H. P. , Rodríguez-Castellanos C.
Published: July 2013

Photon-assisted charge transport through a double barrier structure under a time periodic field in graphene is studied. Within the framework of the Floquet formalism and using the transfer matrix method, the transmission probabilities for the central band and sidebands are calculated. A critical phase difference between the harmonic potentials at the barriers, which cancels transmission through the inelastic sidebands due to quantum interference is found. This phenomenon could be of help to design graphene based filters and high-frequency radiation detectors. Quenching of resonant tunneling by the harmonic field applied to the barriers or the well is also discussed.
Physical evidence of predatory behavior in
Tyrannosaurus rex
Authors: DePalma Robert A. , Burnham David A. , Martin Larry D. , Rothschild Bruce M. , Larson Peter L.
Published: July 2013

Feeding strategies of the large theropod,
Tyrannosaurus rex
, either as a predator or a scavenger, have been a topic of debate previously compromised by lack of definitive physical evidence. Tooth drag and bone puncture marks have been documented on suggested prey items, but are often difficult to attribute to a specific theropod. Further, postmortem damage cannot be distinguished from intravital occurrences, unless evidence of healing is present. Here we report definitive evidence of predation by
T. rex
: a tooth crown embedded in a hadrosaurid caudal centrum, surrounded by healed bone growth. This indicates that the prey escaped and lived for some time after the injury, providing direct evidence of predatory behavior by
T. rex
. The two traumatically fused hadrosaur vertebrae partially enclosing a
T. rex
tooth were discovered in the Hell Creek Formation of South Dakota.
Export of submicron particulate organic matter to mesopelagic depth in an oligotrophic gyre
Authors: Close Hilary G. , Shah Sunita R. , Ingalls Anitra E. , Diefendorf Aaron F. , Brodie Eoin L. , Hansman Roberta L. , Freeman Katherine H. , Aluwihare Lihini I. , Pearson Ann
Published: July 2013

Sixty percent of the world ocean by area is contained in oligotrophic gyres [Longhurst A (1995)
Prog Oceanog
36:77–16], the biomass of which is dominated by picophytoplankton, including cyanobacteria and picoeukaryotic algae, as well as picoheterotrophs. Despite their recognized importance in carbon cycling in the surface ocean, the role of small cells and their detrital remains in the transfer of particulate organic matter (POM) to the deep ocean remains disputed. Because oligotrophic marine conditions are projected to expand under current climate trends, a better understanding of the role of small particles in the global carbon cycle is a timely goal. Here we use the lipid profiles, radiocarbon, and stable carbon isotopic signatures of lipids from the North Pacific Subtropical Gyre to show that in the surface ocean, lipids from submicron POM (here called extra-small POM) are distinct from larger classes of suspended POM. Remarkably, this distinct extra-small POM signature dominates the total lipids collected at mesopelagic depth, suggesting that the lipid component of mesopelagic POM primarily contains the exported remains of small particles. Transfer of submicron material to mesopelagic depths in this location is consistent with model results that claim the biological origin of exported carbon should be proportional to the distribution of cell types in the surface community, irrespective of cell size [Richardson TL, Jackson GA (2007)
Science
315:838–840]. Our data suggest that the submicron component of exported POM is an important contributor to the global biological pump, especially in oligotrophic waters.
The multimillennial sea-level commitment of global warming
Authors: Levermann Anders , Clark Peter U. , Marzeion Ben , Milne Glenn A. , Pollard David , Radic Valentina , Robinson Alexander
Published: July 2013

Global mean sea level has been steadily rising over the last century, is projected to increase by the end of this century, and will continue to rise beyond the year 2100 unless the current global mean temperature trend is reversed. Inertia in the climate and global carbon system, however, causes the global mean temperature to decline slowly even after greenhouse gas emissions have ceased, raising the question of how much sea-level commitment is expected for different levels of global mean temperature increase above preindustrial levels. Although sea-level rise over the last century has been dominated by ocean warming and loss of glaciers, the sensitivity suggested from records of past sea levels indicates important contributions should also be expected from the Greenland and Antarctic Ice Sheets. Uncertainties in the paleo-reconstructions, however, necessitate additional strategies to better constrain the sea-level commitment. Here we combine paleo-evidence with simulations from physical models to estimate the future sea-level commitment on a multimillennial time scale and compute associated regional sea-level patterns. Oceanic thermal expansion and the Antarctic Ice Sheet contribute quasi-linearly, with 0.4 m °C−1and 1.2 m °C−1of warming, respectively. The saturation of the contribution from glaciers is overcompensated by the nonlinear response of the Greenland Ice Sheet. As a consequence we are committed to a sea-level rise of approximately 2.3 m °C−1within the next 2,000 y. Considering the lifetime of anthropogenic greenhouse gases, this imposes the need for fundamental adaptation strategies on multicentennial time scales.
Reducing spread in climate model projections of a September ice-free Arctic
Authors: Liu Jiping , Song Mirong , Horton Radley M. , Hu Yongyun
Published: July 2013

This paper addresses the specter of a September ice-free Arctic in the 21st century using newly available simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5). We find that large spread in the projected timing of the September ice-free Arctic in 30 CMIP5 models is associated at least as much with different atmospheric model components as with initial conditions. Here we reduce the spread in the timing of an ice-free state using two different approaches for the 30 CMIP5 models: (i) model selection based on the ability to reproduce the observed sea ice climatology and variability since 1979 and (ii) constrained estimation based on the strong and persistent relationship between present and future sea ice conditions. Results from the two approaches show good agreement. Under a high-emission scenario both approaches project that September ice extent will drop to ∼1.7 million km2in the mid 2040s and reach the ice-free state (defined as 1 million km2) in 2054–2058. Under a medium-mitigation scenario, both approaches project a decrease to ∼1.7 million km2in the early 2060s, followed by a leveling off in the ice extent.
Crystallization of CO
2
ice and the absence of amorphous CO
2
ice in space
Authors: Escribano Rafael M. , Muñoz Caro Guillermo M. , Cruz-Diaz Gustavo A. , Rodríguez-Lazcano Yamilet , Maté Belén
Published: July 2013

Carbon dioxide (CO
2
) is one of the most relevant and abundant species in astrophysical and atmospheric media. In particular, CO
2
ice is present in several solar system bodies, as well as in interstellar and circumstellar ice mantles. The amount of CO
2
in ice mantles and the presence of pure CO
2
ice are significant indicators of the temperature history of dust in protostars. It is therefore important to know if CO
2
is mixed with other molecules in the ice matrix or segregated and whether it is present in an amorphous or crystalline form. We apply a multidisciplinary approach involving IR spectroscopy in the laboratory, theoretical modeling of solid structures, and comparison with astronomical observations. We generate an unprecedented highly amorphous CO
2
ice and study its crystallization both by thermal annealing and by slow accumulation of monolayers from the gas phase under an ultrahigh vacuum. Structural changes are followed by IR spectroscopy. We also devise theoretical models to reproduce different CO
2
ice structures. We detect a preferential in-plane orientation of some vibrational modes of crystalline CO
2
. We identify the IR features of amorphous CO
2
ice, and, in particular, we provide a theoretical explanation for a band at 2,328 cm
−1
that dominates the spectrum of the amorphous phase and disappears when the crystallization is complete. Our results allow us to rule out the presence of pure and amorphous CO
2
ice in space based on the observations available so far, supporting our current view of the evolution of CO
2
ice.
Reptin/Ruvbl2 is a Lrrc6/Seahorse interactor essential for cilia motility
Authors: Zhao Lu , Yuan Shiaulou , Cao Ying , Kallakuri Sowjanya , Li Yuanyuan , Kishimoto Norihito , DiBella Linda , Sun Zhaoxia
Published: July 2013

Primary ciliary dyskinesia (PCD) is an autosomal recessive disease caused by defective cilia motility. The identified PCD genes account for about half of PCD incidences and the underlying mechanisms remain poorly understood. We demonstrate that Reptin/Ruvbl2, a protein known to be involved in epigenetic and transcriptional regulation, is essential for cilia motility in zebrafish. We further show that Reptin directly interacts with the PCD protein Lrrc6/Seahorse and this interaction is critical for the in vivo function of Lrrc6/Seahorse in zebrafish. Moreover, whereas the expression levels of multiple dynein arm components remain unchanged or become elevated, the density of axonemal dynein arms is reduced in
reptin

hi2394

mutants. Furthermore, Reptin is highly enriched in the cytosol and colocalizes with Lrrc6/Seahorse. Combined, these results suggest that the Reptin-Lrrc6/Seahorse complex is involved in dynein arm formation. We also show that although the DNA damage response is induced in
reptin

hi2394

mutants, it remains unchanged in cilia biogenesis mutants and
lrrc6/seahorse
mutants, suggesting that increased DNA damage response is not intrinsic to ciliary defects and that in vertebrate development, Reptin functions in multiple processes, both cilia specific and cilia independent.
Cell–cell contacts confine public goods diffusion inside
Pseudomonas aeruginosa
clonal microcolonies
Authors: Julou Thomas , Mora Thierry , Guillon Laurent , Croquette Vincent , Schalk Isabelle J. , Bensimon David , Desprat Nicolas
Published: July 2013

The maintenance of cooperation in populations where public goods are equally accessible to all but inflict a fitness cost on individual producers is a long-standing puzzle of evolutionary biology. An example of such a scenario is the secretion of siderophores by bacteria into their environment to fetch soluble iron. In a planktonic culture, these molecules diffuse rapidly, such that the same concentration is experienced by all bacteria. However, on solid substrates, bacteria form dense and packed colonies that may alter the diffusion dynamics through cell–cell contact interactions. In
Pseudomonas aeruginosa
microcolonies growing on solid substrate, we found that the concentration of pyoverdine, a secreted iron chelator, is heterogeneous, with a maximum at the center of the colony. We quantitatively explain the formation of this gradient by local exchange between contacting cells rather than by global diffusion of pyoverdine. In addition, we show that this local trafficking modulates the growth rate of individual cells. Taken together, these data provide a physical basis that explains the stability of public goods production in packed colonies.
Inhibiting the HSP90 chaperone slows cyst growth in a mouse model of autosomal dominant polycystic kidney disease
Authors: Seeger-Nukpezah Tamina , Proia David A. , Egleston Brian L. , Nikonova Anna S. , Kent Tatiana , Cai Kathy Q. , Hensley Harvey H. , Ying Weiwen , Chimmanamada Dinesh , Serebriiskii Ilya G. , Golemis Erica A.
Published: July 2013

Autosomal dominant polycystic kidney disease (ADPKD) is a progressive genetic syndrome with an incidence of 1:500 in the population, arising from inherited mutations in the genes for polycystic kidney disease 1 (
PKD1
) or polycystic kidney disease 2 (
PKD2
). Typical onset is in middle age, with gradual replacement of renal tissue with thousands of fluid-filled cysts, resulting in end-stage renal disease requiring dialysis or kidney transplantation. There currently are no approved therapies to slow or cure ADPKD. Mutations in the
PKD1
and
PKD2
genes abnormally activate multiple signaling proteins and pathways regulating cell proliferation, many of which we observe, through network construction, to be regulated by heat shock protein 90 (HSP90). Inhibiting HSP90 with a small molecule, STA-2842, induces the degradation of many ADPKD-relevant HSP90 client proteins in
Pkd1

−
/
−

primary kidney cells and in vivo. Using a conditional Cre-mediated mouse model to inactivate
Pkd1
in vivo, we find that weekly administration of STA-2842 over 10 wk significantly reduces initial formation of renal cysts and kidney growth and slows the progression of these phenotypes in mice with preexisting cysts. These improved disease phenotypes are accompanied by improved indicators of kidney function and reduced expression and activity of HSP90 clients and their effectors, with the degree of inhibition correlating with cystic expansion in individual animals. Pharmacokinetic analysis indicates that HSP90 is overexpressed and HSP90 inhibitors are selectively retained in cystic versus normal kidney tissue, analogous to the situation observed in solid tumors. These results provide an initial justification for evaluating HSP90 inhibitors as therapeutic agents for ADPKD.
Stone tools and foraging in northern Madagascar challenge Holocene extinction models
Authors: Dewar Robert E. , Radimilahy Chantal , Wright Henry T. , Jacobs Zenobia , Kelly Gwendolyn O. , Berna Francesco
Published: July 2013

Past research on Madagascar indicates that village communities were established about AD 500 by people of both Indonesian and East African heritage. Evidence of earlier visits is scattered and contentious. Recent archaeological excavations in northern Madagascar provide evidence of occupational sites with microlithic stone technologies related to foraging for forest and coastal resources. A forager occupation of one site dates to earlier than 2000 B.C., doubling the length of Madagascar’s known occupational history, and thus the time during which people exploited Madagascar’s environments. We detail stratigraphy, chronology, and artifacts from two rock shelters. Ambohiposa near Iharana (Vohémar) on the northeast coast, yielded a stratified assemblage with small flakes, microblades, and retouched crescentic and trapezoidal tools, probably projectile elements, made on cherts and obsidian, some brought more that 200 km.
14
C dates are contemporary with the earliest villages. No food remains are preserved. Lakaton’i Anja near Antsiranana in the north yielded several stratified assemblages. The latest assemblage is well dated to A.D. 1050–1350, by
14
C and optically stimulated luminescence dating and pottery imported from the Near East and China. Below is a series of stratified assemblages similar to Ambohiposa.
14
C and optically stimulated luminescence dates indicate occupation from at least 2000 B.C. Faunal remains indicate a foraging pattern. Our evidence shows that foragers with a microlithic technology were active in Madagascar long before the arrival of farmers and herders and before many Late Holocene faunal extinctions. The differing effects of historically distinct economies must be identified and understood to reconstruct Holocene histories of human environmental impact.
Self-organized vascular networks from human pluripotent stem cells in a synthetic matrix
Authors: Kusuma Sravanti , Shen Yu-I , Hanjaya-Putra Donny , Mali Prashant , Cheng Linzhao , Gerecht Sharon
Published: July 2013

The success of tissue regenerative therapies is contingent on functional and multicellular vasculature within the redeveloping tissue. Although endothelial cells (ECs), which compose the vasculature’s inner lining, are intrinsically able to form nascent networks, these structures regress without the recruitment of pericytes, supporting cells that surround microvessel endothelium. Reconstruction of typical in vivo microvascular architecture traditionally has been done using distinct cell sources of ECs and pericytes within naturally occurring matrices; however, the limited sources of clinically relevant human cells and the inherent chemical and physical properties of natural materials hamper the translational potential of these approaches. Here we derived a bicellular vascular population from human pluripotent stem cells (hPSCs) that undergoes morphogenesis and assembly in a synthetic matrix. We found that hPSCs can be induced to codifferentiate into early vascular cells (EVCs) in a clinically relevant strategy amenable to multiple hPSC lines. These EVCs can mature into ECs and pericytes, and can self-organize to form microvascular networks in an engineered matrix. These engineered human vascular networks survive implantation, integrate with the host vasculature, and establish blood flow. This integrated approach, in which a derived bicellular population is exploited for its intrinsic self-assembly capability to create microvasculature in a deliverable matrix, has vast ramifications for vascular construction and regenerative medicine.
Refining the pathovar paradigm via phylogenomics of the attaching and effacing
Escherichia coli
Authors: Hazen Tracy H. , Sahl Jason W. , Fraser Claire M. , Donnenberg Michael S. , Scheutz Flemming , Rasko David A.
Published: July 2013

The attaching and effacing
Escherichia coli
(AEEC) are characterized by the presence of a type III secretion system encoded by the locus of enterocyte effacement (LEE). Enterohemorrhagic
E. coli
(EHEC) are often identified as isolates that are LEE+ and carry the Shiga toxin (
stx
)-encoding phage, which are labeled Shiga toxin-producing
E. coli
; whereas enteropathogenic
E. coli
(EPEC) are LEE+ and often carry the EPEC adherence factor plasmid-encoded bundle-forming pilus (
bfp
) genes. All other LEE+
/bfp−/stx−
isolates have been historically designated atypical EPEC. These groups have been defined based on the presence or absence of a limited number of virulence factors, many of which are encoded on mobile elements. This study describes the comparative analysis of the genomes of 114 LEE+
E. coli
isolates. Based on a whole-genome phylogeny and analysis of type III secretion system effectors, the AEEC are divided into five distinct genomic lineages. The LEE+
/stx+/bfp−
genomes were primarily divided into two genomic lineages, the O157/O55 EHEC1 and non-O157 EHEC2. The LEE
+/bfp+/stx−
AEEC isolates sequenced in this study separated into the EPEC1, EPEC2, and EPEC4 genomic lineages. A multiplex PCR assay for identification of each of these AEEC genomic lineages was developed. Of the 114 AEEC genomes analyzed, 31 LEE
+
isolates were not in any of the known AEEC lineages and thus represent unclassified AEEC that in most cases are more similar to other
E. coli
pathovars than to text modification AEEC. Our findings demonstrate evolutionary relationships among diverse AEEC pathogens and the utility of phylogenomics for lineage-specific identification of AEEC clinical isolates.
Structure and function of CarD, an essential mycobacterial transcription factor
Authors: Srivastava Devendra B. , Leon Katherine , Osmundson Joseph , Garner Ashley L. , Weiss Leslie A. , Westblade Lars F. , Glickman Michael S. , Landick Robert , Darst Seth A. , Stallings Christina L. , Campbell Elizabeth A.
Published: July 2013

CarD, an essential transcription regulator in
Mycobacterium tuberculosis
, directly interacts with the RNA polymerase (RNAP). We used a combination of in vivo and in vitro approaches to establish that CarD is a global regulator that stimulates the formation of RNAP-holoenzyme open promoter (RPo) complexes. We determined the X-ray crystal structure of
Thermus thermophilus
CarD, allowing us to generate a structural model of the CarD/RPo complex. On the basis of our structural and functional analyses, we propose that CarD functions by forming protein/protein and protein/DNA interactions that bridge the RNAP to the promoter DNA. CarD appears poised to interact with a DNA structure uniquely presented by the RPo: the splayed minor groove at the double-stranded/single-stranded DNA junction at the upstream edge of the transcription bubble. Thus, CarD uses an unusual mechanism for regulating transcription, sensing the DNA conformation where transcription bubble formation initiates.
Species–fragmented area relationship
Authors: Hanski Ilkka , Zurita Gustavo A. , Bellocq M. Isabel , Rybicki Joel
Published: July 2013

The species–area relationship (SAR) gives a quantitative description of the increasing number of species in a community with increasing area of habitat. In conservation, SARs have been used to predict the number of extinctions when the area of habitat is reduced. Such predictions are most needed for landscapes rather than for individual habitat fragments, but SAR-based predictions of extinctions for landscapes with highly fragmented habitat are likely to be biased because SAR assumes contiguous habitat. In reality, habitat loss is typically accompanied by habitat fragmentation. To quantify the effect of fragmentation in addition to the effect of habitat loss on the number of species, we extend the power-law SAR to the species–fragmented area relationship. This model unites the single-species metapopulation theory with the multispecies SAR for communities. We demonstrate with a realistic simulation model and with empirical data for forest-inhabiting subtropical birds that the species–fragmented area relationship gives a far superior prediction than SAR of the number of species in fragmented landscapes. The results demonstrate that for communities of species that are not well adapted to live in fragmented landscapes, the conventional SAR underestimates the number of extinctions for landscapes in which little habitat remains and it is highly fragmented.
Tumor suppressor gene
Rb
is required for self-renewal of spermatogonial stem cells in mice
Authors: Hu Yueh-Chiang , de Rooij Dirk G. , Page David C.
Published: July 2013

The retinoblastoma tumor suppressor gene
Rb
is essential for maintaining the quiescence and for regulating the differentiation of somatic stem cells. Inactivation of
Rb
in somatic stem cells typically leads to their overexpansion, often followed by increased apoptosis, defective terminal differentiation, and tumor formation. However,
Rb
’s roles in germ-line stem cells have not been explored. We conditionally disrupted the
Rb
gene in mouse germ cells in vivo and discovered unanticipated consequences for GFRa1-protein-expressing A
single
(GFRa1
+
A
s
) spermatogonia, the major source of male germ-line stem cells.
Rb
-deficient GFRa1
+
A
s
spermatogonia were present at normal density in testes 5 d after birth, but they lacked the capacity for self-renewal, resulting in germ cell depletion by 2 mo of age.
Rb
deficiency did not affect the proliferative activity of GFRa1
+
A
s
spermatogonia, but their progeny were exclusively transit-amplifying progenitor spermatogonia and did not include GFRa1
+
A
s
spermatogonia. In addition,
Rb
deficiency caused prolonged proliferation of progenitor spermatogonia, transiently enlarging this population. Despite these defects,
Rb
deficiency did not block terminal differentiation into functional sperm; offspring were readily obtained from young males whose germ cell pool was not yet depleted. We conclude that
Rb
is required for self-renewal of germ-line stem cells, but contrary to its critical roles in somatic stem cells, it is dispensable for their proliferative activity and terminal differentiation. Thus, this study identifies an unexpected function for
Rb
in maintaining the stem cell pool in the male germ line.
Metaphoric cognition as social activity
Authors: Gibbs Raymond W.
Published: July 2013

Metaphoric thought is often viewed as a property of individual minds that is quite separate from people’s social, communicative actions with metaphoric language and gesture. My goal in this article is to argue that metaphoric cognition is fundamentally linked to human social activities. I defend this idea by focusing not only on metaphor use in overt communicative situations, but by suggesting ways that individual metaphoric cognition is implicitly social. Many of the experimental tasks used in psychology to demonstrate the psychological reality of conceptual metaphors reflect intricate couplings between cognitive and social processes. This argument demands a reorientation in how metaphor scholars interpret empirical findings related to conceptual metaphor theory, and more broadly aims to dissolve the long-standing theoretical divide between metaphoric cognition and metaphoric communication.
¿Qué diciendo nomás?
Authors: Lipski John M.
Published: July 2013

In Quechua-dominant Spanish interlanguage in the Andean region the gerund is frequently found instead of finite verb forms typical of monolingual Spanish. Using data collected among Quichua-Spanish bilinguals in northern Ecuador, this study challenges claims that direct transfer of the Quichua subordinator -s(h)pa — often called a “gerund” — is the immediate source of the Andean Spanish gerund. Quichua-dominant bilinguals produce Spanish gerunds mostly in subordinate clauses, reflecting the general pattern of Quechua. However, in a Quichua-to-Spanish translation task, -shpa was most frequently translated as a gerund by school children who had received Quichua language classes, and least frequently by traditional Quichua-dominant speakers. An examination of historical documents suggests that the gerund was used in Spanish foreigner talk directed at indigenous speakers. The ultimate source of the -s(h)pa = Spanish gerund equation is traced to 16th and 17th century Quechua grammars written in the Latinate tradition, and to Spanish priests’ and missionaries’ (mis)appropriation of this grammatical interpretation in their interaction with indigenous speakers in the Andean zone.
The phonological and semantic bifurcation of the functions of an articulator
Authors: Göksel Aslı , Kelepir  Meltem
Published: July 2013

In this article, we analyse the role of the head in content questions and polar questions in Turkish Sign Language (Türk İşaret Dili — TİD). We claim that the head not only robustly marks the difference between these two types, but in addition marks an utterance as having interrogative mood. We show that the two functions, the overarching category interrogative mood and the subtypes of interrogatives, have separate phonological exponents, both of which are expressed simultaneously by a single articulator, the head.
“German speakers, step forward!”
Authors: Wolf Michaela
Published: July 2013

In Nazi concentration camps the prisoners were frequently of 30 to 40 different nationalities, and German and Polish Jews were in the majority. With German as the only official language in the lager, communication was vital for the prisoners’ survival. In the last few decades, there has been extensive research on the language inmates used (referred to as “lagerszpracha,” “lagerjargon,” or “Krematorium-Esperanto”); investigation, however, of the mediating role of interpreters between SS guards and prisoners, on the one hand, and among inmates, on the other, has been nearly inexistent. This paper claims that the different kinds of interpreting activities shaped the everyday life in concentration camps considerably. In what way has interpreting contributed to the survival of the deported? Did interpreting have an impact on the hierarchical order imposed on the prisoners? What metaphors can best describe the interpreting activity in order to convey the extreme terror the lager prisoners experienced? These questions will be explored through a series of survivor accounts.
Crowdsourcing, corpus use, and the search for translation naturalness
Authors: Jiménez-Crespo Miguel A.
Published: July 2013

This paper argues that corpus use in translation and the Facebook non-professional crowdsourcing model both aim to create more natural-sounding translations. A number of studies on corpus use support this hypothesis, but, to date, there have been no empirical studies on whether crowdsourcing translations produces texts that comply with the conventions users expect, consequently appearing more natural. After a theoretical discussion on how corpus use and Facebook crowdsourcing both intend to achieve more naturally sounding translations, the empirical study contrasts the crowdsourced Peninsular Spanish version of Facebook to original Spanish social networking sites. The methodology is based on a comparable corpus (Baker 1995) and compares all the interactive segments, such as navigation menus and dialog boxes, in this version of Facebook to a similar corpus extracted from the top 25 social networks locally produced in Spain. The contrastive analyses focus on verbal use and terminological conventions. The results confirm that the linguistic features examined in Facebook and produced through a crowdsourced non-professional model match those found in the corpus of non-translated networking sites.
“Somebody has to be in charge of a session”
Authors: Zimányi Krisztina
Published: July 2013

Interpreting between a minority language speaker or user (a service user or client) and a representative of an authority (service provider) is frequently referred to as Community Interpreting. One of the challenges of such triadic communication between linguistically and culturally diverse participants is to establish who may speak for how long in order to maintain meaningful communication without any loss of information. At first glance, the service provider emerges as the apparent figure of authority, while the client often provides significant input concerning the content of the encounter. Nevertheless, the final responsibility for the information transfer rests with the interpreter. This article reports on how participants of a study conducted in the area of interpreting in mental healthcare in Dublin, Ireland viewed the issue of communication control. Interview respondents of the research, who comprised mental health professionals and interpreters working in mental healthcare, revealed that there is a constantly fluctuating delicate balance regarding the control of the communication flow when an interpreter is involved in an encounter between a service user and a service provider.
The English School and the concept of ‘empire’: theoretical and practical/political implications
Authors: Stivachtis Yannis A.
Published: July 2013

The English School (ES) of International Relations is mainly associated with the idea of ‘international society’ defined as a group of states bound by a common set of rules in their relations with one another and sharing in the working of common institutions. However, the idea of ‘empire’ has posed some challenges to ES thinking. Consequently, some ES scholars have viewed ‘empire’ as a form of statehood and, therefore, as constituting one of the units in an international society. Some others have considered ‘empire’ as a form of an international society in itself while others have treated it as a form of a ‘world society’. Because the ideas of ‘international’ and ‘world society’ are associated with particular, norms, rules, practices, and policies, the present article aims at addressing this controversy within the ES and examining the political implications stemming from the various ES usages of the concept of ‘empire’.
CEP120 interacts with CPAP and positively regulates centriole elongation
Authors: Lin Yi-Nan , Wu Chien-Ting , Lin Yu-Chih , Hsu Wen-Bin , Tang Chieh-Ju C. , Chang Ching-Wen , Tang Tang K.
Published: July 2013

Centriole duplication begins with the formation of a single procentriole next to a preexisting centriole. CPAP (centrosomal protein 4.1–associated protein) was previously reported to participate in centriole elongation. Here, we show that CEP120 is a cell cycle–regulated protein that directly interacts with CPAP and is required for centriole duplication. CEP120 levels increased gradually from early S to G2/M and decreased significantly after mitosis. Forced overexpression of either CEP120 or CPAP not only induced the assembly of overly long centrioles but also produced atypical supernumerary centrioles that grew from these long centrioles. Depletion of CEP120 inhibited CPAP-induced centriole elongation and vice versa, implying that these proteins work together to regulate centriole elongation. Furthermore, CEP120 was found to contain an N-terminal microtubule-binding domain, a C-terminal dimerization domain, and a centriolar localization domain. Overexpression of a microtubule binding–defective CEP120-K76A mutant significantly suppressed the formation of elongated centrioles. Together, our results indicate that CEP120 is a CPAP-interacting protein that positively regulates centriole elongation.
Kinesin-1–syntaphilin coupling mediates activity-dependent regulation of axonal mitochondrial transport
Authors: Chen Yanmin , Sheng Zu-Hang
Published: July 2013

Axonal mitochondria are recruited to synaptic terminals in response to neuronal activity, but the mechanisms underlying activity-dependent regulation of mitochondrial transport are largely unknown. In this paper, using genetic mouse model combined with live imaging, we demonstrate that syntaphilin (SNPH) mediates the activity-dependent immobilization of axonal mitochondria through binding to KIF5. In vitro analysis showed that the KIF5–SNPH coupling inhibited the motor adenosine triphosphatase. Neuronal activity further recruited SNPH to axonal mitochondria. This motor-docking interplay was induced by Ca2+ and synaptic activity and was necessary to establish an appropriate balance between motile and stationary axonal mitochondria. Deleting snph abolished the activity-dependent immobilization of axonal mitochondria. We propose an “Engine-Switch and Brake” model, in which SNPH acts both as an engine off switch by sensing mitochondrial Rho guanosine triphosphatase-Ca2+ and as a brake by anchoring mitochondria to the microtubule track. Altogether, our study provides new mechanistic insight into the molecular interplay between motor and docking proteins, which arrests axonal mitochondrial transport in response to changes in neuronal activity.
The actin-binding ERM protein Moesin binds to and stabilizes microtubules at the cell cortex
Authors: Solinet Sara , Mahmud Kazi , Stewman Shannon F. , Ben El Kadhi Khaled , Decelle Barbara , Talje Lama , Ma Ao , Kwok Benjamin H. , Carreno Sébastien
Published: July 2013

Ezrin, Radixin, and Moesin (ERM) proteins play important roles in many cellular processes including cell division. Recent studies have highlighted the implications of their metastatic potential in cancers. ERM’s role in these processes is largely attributed to their ability to link actin filaments to the plasma membrane. In this paper, we show that the ERM protein Moesin directly binds to microtubules in vitro and stabilizes microtubules at the cell cortex in vivo. We identified two evolutionarily conserved residues in the FERM (4.1 protein and ERM) domains of ERMs that mediated the association with microtubules. This ERM–microtubule interaction was required for regulating spindle organization in metaphase and cell shape transformation after anaphase onset but was dispensable for bridging actin filaments to the metaphase cortex. These findings provide a molecular framework for understanding the complex functional interplay between the microtubule and actin cytoskeletons mediated by ERM proteins in mitosis and have broad implications in both physiological and pathological processes that require ERMs.