bluuebunny/crossref_metadata_2025 huggingface dataset:
Glass transition temperature and topological constraints of sodium borophosphate glass-forming liquids
Authors: Jiang Qi , Zeng Huidan , Liu Zhao , Ren Jing , Chen Guorong , Wang Zhaofeng , Sun Luyi , Zhao Donghui
Published: September 2013

Sodium borophosphate glasses exhibit intriguing mixed network former effect, with the nonlinear compositional dependence of their glass transition temperature as one of the most typical examples. In this paper, we establish the widely applicable topological constraint model of sodium borophosphate mixed network former glasses to explain the relationship between the internal structure and nonlinear changes of glass transition temperature. The application of glass topology network was discussed in detail in terms of the unified methodology for the quantitative distribution of each coordinated boron and phosphorus units and glass transition temperature dependence of atomic constraints. An accurate prediction of composition scaling of the glass transition temperature was obtained based on topological constraint model.
Easily implementable field programmable gate array-based adaptive optics system with state-space multichannel control
Authors: Chang Chia-Yuan , Ke Bo-Ting , Su Hung-Wei , Yen Wei-Chung , Chen Shean-Jen
Published: September 2013

In this paper, an easily implementable adaptive optics system (AOS) based on a real-time field programmable gate array (FPGA) platform with state-space multichannel control programmed by LabVIEW has been developed, and also integrated into a laser focusing system successfully. To meet the requirements of simple programming configuration and easy integration with other devices, the FPGA-based AOS introduces a standard operation procedure including AOS identification, computation, and operation. The overall system with a 32-channel driving signal for a deformable mirror (DM) as input and a Zernike polynomial via a lab-made Shack-Hartmann wavefront sensor (SHWS) as output is optimally identified to construct a multichannel state-space model off-line. In real-time operation, the FPGA platform first calculates the Zernike polynomial of the optical wavefront measured from the SHWS as the feedback signal. Then, a state-space multichannel controller according to the feedback signal and the identified model is designed and implemented in the FPGA to drive the DM for phase distortion compensation. The current FPGA-based AOS is capable of suppressing low-frequency thermal disturbances with a steady-state phase error of less than 0.1 π within less than 10 time steps when the control loop is operated at a frequency of 30 Hz.
High-temperature experiments using a resistively heated high-pressure membrane diamond anvil cell
Authors: Jenei Zsolt , Cynn Hyunchae , Visbeck Ken , Evans William J.
Published: September 2013

We describe a reliable high performance resistive heating method developed for the membrane diamond anvil cell. This method generates homogenous high temperatures at high pressure in the whole sample for extended operation period. It relies on two mini coil heaters made of Pt-Rh alloy wire mounted around the diamond anvils and gasket, while temperature is monitored by two K-type thermocouples mounted near the sample. The sample, diamonds, and tungsten-carbide seats are thermally insulated from the piston and cylinder keeping the cell temperature below 750 K while the sample temperature is 1200 K. The cell with the heaters is placed in a vacuum oven to prevent oxidation and unnecessary heat loss. This assembly allows complete remote operation, ideally suited for experiments at synchrotron facilities. Capabilities of the setup are demonstrated for in situ Raman and synchrotron x-ray diffraction measurements. We show experimental measurements from isothermal compression at 900 K and 580 K to 100 GPa and 185 GPa, respectively, and quasi-isobaric compression at 95 GPa over 1000 K.
The dielectric properties enhancement due to Yb incorporation into HfO2
Authors: Chen Shuai , Liu Zhengtang , Feng Liping , Che Xingsen , Zhao Xiaoru
Published: September 2013

The effects of Yb concentration and annealing temperature on the dielectric constant change of Yb-doped HfO2 thin film were investigated. The results show that the dielectric constant of Yb-doped HfO2 increased when doping with Yb after annealing. Compared with the undoped HfO2, the dielectric constant enhancement may result from the crystallographic change from monoclinic phase to the cubic phase. The Yb-doped HfO2 exhibited a lower leakage current than that of undoped HfO2 thin film. The electrical characteristics of Yb-doped HfO2 thin film illustrated that it is a promising gate dielectric layer for future high dielectric constant (high-k) gate dielectric applications.
High-amplitude dynamics of nanoelectromechanical systems fabricated on the basis of GaAs/AlGaAs heterostructures
Authors: Shevyrin A. A. , Pogosov A. G. , Budantsev M. V. , Bakarov A. K. , Toropov A. I. , Ishutkin S. V. , Shesterikov E. V. , Arakcheev A. S.
Published: September 2013

Nonlinear vibrations of nanoelectromechanical beam fabricated from the GaAs/AlGaAs heterostructure containing two-dimensional electron gas are investigated. The measurement of time-averaged conductance is shown to be a sensitive method for the nanomechanical motion detection. The possibilities to excite high-amplitude (up to 20 nm) mechanical vibrations and to effectively detect them using the simple conductance measurement make such systems promising for practical applications. High-amplitude vibrations of the beam are shown to demonstrate softening nonlinearity. This can be attributed to the bending of the beam due to Euler buckling instability caused by the compressive stress though GaAs/AlGaAs heterostructures are typically considered as stress-free.
Terahertz detection in zero-bias InAs self-switching diodes at room temperature
Authors: Westlund Andreas , Sangaré Paul , Ducournau Guillaume , Nilsson Per-Åke , Gaquière Christophe , Desplanque Ludovic , Wallart Xavier , Grahn Jan
Published: September 2013

RF characterization of InAs self-switching diodes (SSDs) is reported. On-wafer measurements revealed no roll-off in responsivity in the range of 2–315 GHz. At 50 GHz, a responsivity of 17 V/W and a noise-equivalent power (NEP) of 150 pW/Hz½ was observed for the SSD when driven by a 50 Ω source. With a conjugately matched source, a responsivity of 34 V/W and an NEP of 65 pW/Hz½ were estimated. An antenna-coupled SSD demonstrated a responsivity of 0.7 V/W at 600 GHz. The results demonstrate the feasibility of zero-bias terahertz detection with high-electron mobility InAs SSDs up to and beyond 100 GHz.
Dynamics in hybrid complex systems of switches and oscillators
Authors: Taylor Dane , Fertig Elana J. , Restrepo Juan G.
Published: September 2013

While considerable progress has been made in the analysis of large systems containing a single type of coupled dynamical component (e.g., coupled oscillators or coupled switches), systems containing diverse components (e.g., both oscillators and switches) have received much less attention. We analyze large, hybrid systems of interconnected Kuramoto oscillators and Hopfield switches with positive feedback. In this system, oscillator synchronization promotes switches to turn on. In turn, when switches turn on, they enhance the synchrony of the oscillators to which they are coupled. Depending on the choice of parameters, we find theoretically coexisting stable solutions with either (i) incoherent oscillators and all switches permanently off, (ii) synchronized oscillators and all switches permanently on, or (iii) synchronized oscillators and switches that periodically alternate between the on and off states. Numerical experiments confirm these predictions. We discuss how transitions between these steady state solutions can be onset deterministically through dynamic bifurcations or spontaneously due to finite-size fluctuations.
Implementation of tetra-poly(ethylene glycol) hydrogel with high mechanical strength into microfluidic device technology
Authors: Takehara Hiroaki , Nagaoka Akira , Noguchi Jun , Akagi Takanori , Sakai Takamasa , Chung Ung-il , Kasai Haruo , Ichiki Takanori
Published: September 2013

Hydrogels have several excellent characteristics suitable for biomedical use such as softness, biological inertness and solute permeability. Hence, integrating hydrogels into microfluidic devices is a promising approach for providing additional functions such as biocompatibility and porosity, to microfluidic devices. However, the poor mechanical strength of hydrogels has severely limited device design and fabrication. A tetra-poly(ethylene glycol) (tetra-PEG) hydrogel synthesized recently has high mechanical strength and is expected to overcome such a limitation. In this research, we have comprehensively studied the implementation of tetra-PEG gel into microfluidic device technology. First, the fabrication of tetra-PEG gel/PDMS hybrid microchannels was established by developing a simple and robust bonding technique. Second, some fundamental features of tetra-PEG gel/PDMS hybrid microchannels, particularly fluid flow and mass transfer, were studied. Finally, to demonstrate the unique application of tetra-PEG-gel-integrated microfluidic devices, the generation of patterned chemical modulation with the maximum concentration gradient: 10% per 20 μm in a hydrogel was performed. The techniques developed in this study are expected to provide fundamental and beneficial methods of developing various microfluidic devices for life science and biomedical applications.
Impact of compressive in-plane strain on the ferroelectric properties of epitaxial NaNbO3 films on (110) NdGaO3
Authors: Wördenweber R. , Schwarzkopf J. , Hollmann E. , Duk A. , Cai B. , Schmidbauer M.
Published: September 2013

Epitaxial a-axis oriented NaNbO3 films are grown on (110) oriented NdGaO3 substrates. The lattice mismatch between substrate and film leads to compressive strain of ∼0.7% in the a-c plane. As a consequence, the in-plane permittivity and tunability are strongly enhanced compared to bulk NaNbO3, and a pronounced maximum in the temperature dependence of the permittivity occurs. Below the maximum at Tmax ≈ 250 K, ferroelectric behavior is observed that seems to vanish above Tmax. The pristine phase of the film at T < Tmax is antiferroelectric and is easily suppressed by small applied electric fields. The ferroelectric phase shows a relaxor type behavior.
Selection for increased muscling is not detrimental to maternal productivity traits in Angus cows
Authors: Cafe L. M. , McKiernan W. A. , Robinson D. L.
Published: September 2013

The aim of the present study was to assess the effect of selection for increased muscling on maternal productivity of a temperate beef cow herd. Cows of predominantly Angus breeding were selected using visual muscle score (1–15 scale, where 1 = lightest and 15 = heaviest muscling) into low- and high-muscled animals, and mated to Angus bulls with low or high muscularity. Initially, low-muscled cows were mated to low-muscled bulls to create the Low line, and high-muscled bulls and cows were mated to create the High line. On discovering that some High cattle carried the myostatin (821 del11) gene, a second High line was created to distinguish between cattle with no copies of the myostatin gene (High line) and those with one copy (HighHet line). Data from 12 breeding cycles, consisting of 2003 joining records, and 1713 resulting weaning records were analysed to assess maternal productivity. Cows from the three lines were similar in weight (547, 548 and 550 kg, P = 0.9), but varied in body composition – from Low to High to HighHet cows, muscling traits increased and fatness traits decreased (all P < 0.001). Compared with Low cows, High cows had a 4.4 units higher muscle score, 10% higher eye muscle area and 21% less fat, and HighHet cows had a 7.1 units higher muscle score, 17% higher eye muscle area and 45% less fat. There were no significant effects of selection for increased muscling on live birth or weaning rates, or weaning weight (all P > 0.1). Dystocia levels of Low and HighHet maidens or cows did not differ significantly, but High maidens or cows had less dystocia (P = 0.013). Low, High and HighHet cows weaned 218, 225 and 216 kg of calf/cow joined.year, indicating similar maternal productivity.
NF-κB inhibitor targeted to activated endothelium demonstrates a critical role of endothelial NF-κB in immune-mediated diseases
Authors: Sehnert Bettina , Burkhardt Harald , Wessels Johannes T. , Schröder Agnes , May Michael J. , Vestweber Dietmar , Zwerina Jochen , Warnatz Klaus , Nimmerjahn Falk , Schett Georg , Dübel Stefan , Voll Reinhard Edmund
Published: September 2013

Significance

The transcription factor NF-κB is crucially involved in the pathogenesis of inflammatory diseases and represents a target for treatment. However, a general blockade of NF-κB by small-molecule inhibitors is associated with serious side effects due to the importance of NF-κB in cellular survival and function of various organs. This paper demonstrates that cell type-specific NF-κB inhibition can be achieved using multi-modular fusion proteins, which exclusively target activated endothelial cells. Inhibition of NF-κB within activated endothelium potently ameliorated peritonitis and arthritis in mice, indicating that endothelial NF-κB might be a valid target in inflammatory diseases. Importantly, this strategy enables the targeting of other cell types and intracellular signaling pathways.
Preverbal infants expect members of social groups to act alike
Authors: Powell Lindsey J. , Spelke Elizabeth S.
Published: September 2013

Significance

Adults and children conform to members of their social groups and expect others to do the same, but the earlier development of this expectation is unknown. Through looking-time experiments with 7- to 12-month-old infants, we show that preverbal infants expect members of social groups to act alike. Our findings further reveal that this expectation is specific to social groups, as infants did not expect similar actions from socially unrelated individuals or from groups of inanimate objects. Thus, an expectation that social affiliates will share behaviors arises early in human development, prior to language or to extensive experience with different social groups.
Existence of an information unit as a postulate of quantum theory
Authors: Masanes Lluís , Müller Markus P. , Augusiak Remigiusz , Pérez-García David
Published: September 2013

Significance

Despite the enormous success of quantum theory, its significance and meaning are still being debated. In particular, the standard postulates of quantum theory are abstract mathematical statements in terms of complex vectors, self-adjoint operators, etc., and as such they lack a clear physical interpretation. For this reason, it is difficult to assess what they say about the structure of the physical world. In this article, we prove that quantum theory can be formulated through four very simple postulates, each having a direct physical and intuitive meaning. Also, our postulates unveil some connections between physics and information that remain hidden in the standard postulates, thus supporting Wheeler’s hypothesis “it from bit.”
Enhanced anticancer activity of nanopreparation containing an MMP2-sensitive PEG-drug conjugate and cell-penetrating moiety
Authors: Zhu Lin , Wang Tao , Perche Federico , Taigind Anton , Torchilin Vladimir P.
Published: September 2013

Significance

The clinical outcomes of anticancer drugs are compromised by their poor physicochemical properties, low tumor targeting, insufficient bioavailability, and side effects. Matrix metalloproteinase 2 (MMP2) has been found overexpressed in most cancers and responsible for tumor cell proliferation and metastasis. In this study, a self-assembling MMP2-sensitive paclitaxel-containing micellar nanopreparation was developed. Several major drug delivery strategies, including self-assembly, PEGylation, the enhanced permeability and retention effect, stimulus sensitivity, a cell-penetrating moiety, and the concept of prodrug, were used in a collaborative fashion to design this nanoparticle. The nanopreparation showed superior tumor targeting, cell internalization, and antitumor efficacy over its nonsensitive counterpart, free paclitaxel and conventional micelles. This uniquely engineered nanoparticle has potential for effective intracellular delivery of drug into cancer cells.
Phosphate release coupled to rotary motion of F
1
-ATPase
Authors: Okazaki Kei-ichi , Hummer Gerhard
Published: September 2013

Significance

F
1
-ATPase is the catalytic domain of F
o
F
1
-ATP synthase, the rotary molecular motor at the core of the energy transduction machinery in all of life. We use atomistic molecular dynamics simulations to study a key event in its catalytic cycle, the release of inorganic phosphate (P
i
) produced by the hydrolysis of ATP. We determine the timing, kinetics, and molecular mechanism of P
i
release and clarify its role in torque generation. We also obtain an atomically detailed structure of a crystallographically unresolved intermediate formed after the 40° substep. Our results help reconcile conflicting interpretations of earlier biochemical, crystallographic, and single-molecule studies; shed light on the functional requirements of efficient ATP synthesis; and establish connections to other motors such as myosin.
Chain conformations dictate multiscale charge transport phenomena in disordered semiconducting polymers
Authors: Noriega Rodrigo , Salleo Alberto , Spakowitz Andrew J.
Published: September 2013

Significance

Semiconducting polymers have promising applications in transistors, light-emitting diodes, and solar cells. These materials have microstructures that exhibit heterogeneity over multiple length scales, which obscures the relationship between properties, processing conditions, and device performance. Our work provides a theoretical framework to address the role of polymer conformations in electronic transport through disordered semiconducting polymers. We present a simple model that reconciles observations at the local scale with device-scale measurements of charge mobility (charges move quickly at short distances and slowly at long distances). The main features are the use of well-known models to describe the conformations of individual polymer chains and the inclusion of the kinetics of electronic transport between sites on a single polymer and between adjacent chains.
Robust increases in severe thunderstorm environments in response to greenhouse forcing
Authors: Diffenbaugh Noah S. , Scherer Martin , Trapp Robert J.
Published: September 2013

Significance

Severe thunderstorms are one of the primary causes of catastrophic loss in the United States. However, the response of such storms to elevated greenhouse forcing has remained highly uncertain. We use an ensemble of global climate model experiments to probe the severe thunderstorm response. We find that this ensemble exhibits robust increases in the occurrence of severe thunderstorm environments over the eastern United States. In addition, the simulated changes in the atmospheric environment indicate an increase in the number of days supportive of the spectrum of convective hazards, with the suggestion of a possible increase in the number of days supportive of tornadic storms. Given current vulnerabilities, such increases imply increasing risk of thunderstorm-related damage if global warming continues.
War, space, and the evolution of Old World complex societies
Authors: Turchin Peter , Currie Thomas E. , Turner Edward A. L. , Gavrilets Sergey
Published: September 2013

Significance

How did human societies evolve from small groups, integrated by face-to-face cooperation, to huge anonymous societies of today? Why is there so much variation in the ability of different human populations to construct viable states? We developed a model that uses cultural evolution mechanisms to predict where and when the largest-scale complex societies should have arisen in human history. The model was simulated within a realistic landscape of the Afroeurasian landmass, and its predictions were tested against real data. Overall, the model did an excellent job predicting empirical patterns. Our results suggest a possible explanation as to why a long history of statehood is positively correlated with political stability, institutional quality, and income per capita.
Nrf2 acts cell-autonomously in endothelium to regulate tip cell formation and vascular branching
Authors: Wei Yanhong , Gong Junsong , Thimmulappa Rajesh K. , Kosmider Beata , Biswal Shyam , Duh Elia J.
Published: September 2013

Significance

Angiogenesis, in which new blood vessels form via endothelial cell (EC) sprouting from existing vessels, is critical in embryonic development and multiple disease processes. The intracellular molecular mechanisms governing sprouting angiogenesis remain incompletely understood. We found that transcription factor NF-E2–related factor 2 (Nrf2), well-known for regulating the stress response in multiple pathologic settings, is a critical intracellular regulator in ECs for sprouting angiogenesis in vascular development through delta-like 4 (Dll4)/Notch signaling. Understanding the molecular mechanisms by which Nrf2 regulates angiogenesis could facilitate therapeutic strategies targeting Nrf2 to treat angiogenesis-related diseases, including tumorigenesis, proliferative diabetic retinopathy, atherosclerosis, and ischemic disorders.
Perturbation of the left inferior frontal gyrus triggers adaptive plasticity in the right homologous area during speech production
Authors: Hartwigsen Gesa , Saur Dorothee , Price Cathy J. , Ulmer Stephan , Baumgaertner Annette , Siebner Hartwig R.
Published: September 2013

Significance

The role of the right hemisphere in aphasia recovery is unclear. We demonstrate that a virtual lesion of left inferior frontal gyrus (IFG) decreased activity in the targeted area and increased activity in the contralateral homologous area during pseudoword repetition. This was associated with a stronger facilitatory drive from the right IFG to the left IFG. Importantly, responses became faster with increased influence of the right IFG on the left IFG. Our results shed new light on the dynamic regulation of interhemispheric interactions in the human brain. Particularly, these findings are of potential importance for understanding language recovery after left-hemispheric stroke, indicating that homologous right hemisphere areas actively contribute to language function after a left hemisphere lesion.
Social stress up-regulates inflammatory gene expression in the leukocyte transcriptome via β-adrenergic induction of myelopoiesis
Authors: Powell Nicole D. , Sloan Erica K. , Bailey Michael T. , Arevalo Jesusa M. G. , Miller Gregory E. , Chen Edith , Kobor Michael S. , Reader Brenda F. , Sheridan John F. , Cole Steven W.
Published: September 2013

Significance

Chronic exposure to adverse social environments is associated with increased risk of disease, and stress-related increases in the expression of proinflammatory genes appear to contribute to these effects. The present study identifies a biological mechanism of such effects in the ability of the sympathetic nervous system to up-regulate bone marrow production of immature, proinflammatory monocytes. These effects are mediated by β-adrenergic receptors and the myelopoietic growth factor GM-CSF, and suggest new targets for interventions to protect health in the context of chronic social stress.
Middle East respiratory syndrome coronavirus (MERS-CoV) causes transient lower respiratory tract infection in rhesus macaques
Authors: de Wit Emmie , Rasmussen Angela L. , Falzarano Darryl , Bushmaker Trenton , Feldmann Friederike , Brining Douglas L. , Fischer Elizabeth R. , Martellaro Cynthia , Okumura Atsushi , Chang Jean , Scott Dana , Benecke Arndt G. , Katze Michael G. , Feldmann Heinz , Munster Vincent J.
Published: September 2013

Significance

The Middle East respiratory syndrome coronavirus (MERS-CoV) is the latest emerged coronavirus causing severe respiratory disease with a high case fatality rate in humans. To better understand the disease caused by MERS-CoV, we developed a rhesus macaque model. Infection of rhesus macaques with MERS-CoV resulted in the rapid development of a transient pneumonia, with MERS-CoV replication largely restricted to the lower respiratory tract. This affinity of MERS-CoV for the lungs partly explains the severity of the disease observed in humans. The MERS-CoV rhesus macaque model will be instrumental in developing and testing vaccine and treatment options for an emerging viral pathogen with pandemic potential.
Electron transfer precedes ATP hydrolysis during nitrogenase catalysis
Authors: Duval Simon , Danyal Karamatullah , Shaw Sudipta , Lytle Anna K. , Dean Dennis R. , Hoffman Brian M. , Antony Edwin , Seefeldt Lance C.
Published: September 2013

Significance

Biological reduction of dinitrogen (N
2
) to ammonia (NH
3
) occurs in a select group of bacteria that contain the metalloenzyme nitrogenase. To catalyze this difficult reaction, nitrogenase requires electrons, protons, and ATP. From the earliest studies of nitrogenase, it was realized that ATP hydrolysis is coupled to delivery of electrons and reduction of N
2
, yet the order of ATP hydrolysis and electron transfer, which determines the nature of the coupling, was never established. In this work, we establish the order of all the key events during one catalytic cycle of electron delivery in nitrogenase, showing that ATP hydrolysis follows electron transfer. These findings guide future studies aimed at understanding what roles ATP binding and hydrolysis play in the nitrogenase mechanism.
Properties of Slo1 K
+
channels with and without the gating ring
Authors: Budelli Gonzalo , Geng Yanyan , Butler Alice , Magleby Karl L. , Salkoff Lawrence
Published: September 2013

Significance

High-conductance Slo1 (BK) K
+
channels are synergistically activated by Ca
2+
, voltage, Mg
2+
, and additional factors to modulate membrane excitability in many key physiological processes. Slo1 channels are of modular design with allosteric interactions between the core transmembrane modules and a large cytoplasmic gating ring module, providing a model system to study allosteric principles in channel gating and protein function. To examine the allosteric interactions, we developed constructs that replace the large gating ring module with short peptides and then characterized the altered properties of the gating. Our studies, which provide insight into functional and allosteric interactions between the core and the gating ring, may be useful in understanding the disease processes associated with Slo1-channel dysfunction.
Historical warming reduced due to enhanced land carbon uptake
Authors: Shevliakova Elena , Stouffer Ronald J. , Malyshev Sergey , Krasting John P. , Hurtt George C. , Pacala Stephen W.
Published: September 2013

Significance

This article provides estimates of the climate benefits due to CO
2
fertilization of the terrestrial biosphere. Without these benefits, the atmospheric CO
2
concentration would have risen by ∼200 ppm since the preindustrial period instead of the observed ∼115 ppm (an 80% increase), and the global climate would have warmed by an additional 0.31 ± 0.06 °C (a 40% increase). These findings were obtained with a National Oceanic and Atmospheric Administration/Geophysical Fluid Dynamics Laboratory comprehensive Earth System Model ESM2G.
Precocious cerebellum development and improved motor functions in mice lacking the astrocyte cilium-, patched 1-associated Gpr37l1 receptor
Authors: Marazziti Daniela , Di Pietro Chiara , Golini Elisabetta , Mandillo Silvia , La Sala Gina , Matteoni Rafaele , Tocchini-Valentini Glauco P.
Published: September 2013

Significance

A new mouse mutant strain carrying a genetic deletion of the G-protein–coupled receptor 37l1 (Gpr37l1) was established and characterized. Null mutant animals exhibit specific alterations of postnatal cerebellar development, with premature down-regulation of granule neuron proliferation, precocious Bergmann glia, and Purkinje neuron maturation and layer formation. The postnatal expression of several components of the sonic hedgehog protein mitogenic pathway is consistently changed in cerebellar samples from Gpr37l1 knock-out mice. These alterations are associated with precocious juvenile motor abilities and improved adult motor learning and coordination. The Gpr37l1 and patched 1 proteins are found to colocalize and interact in Bergmann glia cells during cerebellar development. The reported experimental data indicate that Gpr37l1 participates in the regulation of sonic hedgehog signaling during postnatal cerebellar development.
Broad domain generality in focal regions of frontal and parietal cortex
Authors: Fedorenko Evelina , Duncan John , Kanwisher Nancy
Published: September 2013

Significance

One of the oldest debates in cognitive neuroscience concerns the degree of functional specialization present in the human brain. Prior work has discovered several highly specialized components dedicated to particular mental functions, like face recognition or motion perception. However, our cognitive versatility suggests the additional existence of more general-purpose machinery. Building on prior neuroimaging evidence, along with neurophysiological evidence from non-human primates, we searched for such domain-general brain regions in humans. Seven diverse demanding cognitive tasks produced overlapping activation at the individual-subject level in a number of frontal and parietal brain regions. Thus, human cognition arises from hardware that includes not only specialized components, but also very general-purpose ones that plausibly enable us to solve novel problems.
Strong cross-system interactions drive the activation of the QseB response regulator in the absence of its cognate sensor
Authors: Guckes Kirsten R. , Kostakioti Maria , Breland Erin J. , Gu Alice P. , Shaffer Carrie L. , Martinez Charles R. , Hultgren Scott J. , Hadjifrangiskou Maria
Published: September 2013

Significance

Bacteria use regulatory modules called two-component systems to respond to changes in their surrounding environment. Bacteria have evolved ways to insulate each two-component system, thereby preventing unwanted cross-talk. Here we describe an example where partners of distinct two-component systems show remarkable cross-specificity for each other. Loss of the quorum-sensing
Escherichia coli
(Qse)BC sensor QseC leads to robust cross-interaction of its cognate partner QseB with the polymyxin resistance (Pmr)AB two-component system. This cross-interaction in the absence of the cognate sensor is detrimental, severely attenuating pathogen virulence. Our findings suggest that (
i
) robust cross-talk between noncognate partners is possible and (
ii
) this interaction can be manipulated for developing antivirulence strategies against uropathogenic
E. coli
and potentially other QseBC−PmrAB-bearing pathogens.
On reversible H
2
loss upon N
2
binding to FeMo-cofactor of nitrogenase
Authors: Yang Zhi-Yong , Khadka Nimesh , Lukoyanov Dmitriy , Hoffman Brian M. , Dean Dennis R. , Seefeldt Lance C.
Published: September 2013

Significance

Biological reduction of dinitrogen (N
2
) to two ammonia (NH
3
) is catalyzed by the metalloenzyme, nitrogenase. A central aspect of nitrogenase function is an apparently obligatory formation of one H
2
per N
2
reduced, with a resulting “waste” of the energy required to deliver two electrons/protons, obtained from hydrolysis of four ATP. We here report experiments that confirm the essential mechanistic role for H
2
formation, and hence a limiting stoichiometry for biological nitrogen fixation of eight electrons/protons, not six as in the equation N
2
+ 3H
2
→ 2NH
3
. These experiments were devised to test our recently proposed “reductive elimination” mechanism for H
2
formation and the activation of nitrogenase for ammonia production. Our findings provide direct experimental support for that mechanism.
Short-term synaptic plasticity in the deterministic Tsodyks–Markram model leads to unpredictable network dynamics
Authors: Cortes Jesus M. , Desroches Mathieu , Rodrigues Serafim , Veltz Romain , Muñoz Miguel A. , Sejnowski Terrence J.
Published: September 2013

Significance

Short-term synaptic plasticity contributes to the balance and regulation of brain networks from milliseconds to several minutes. In this paper we report the existence of a route to chaos in the Tsodyks and Markram model of short-term synaptic plasticity. The chaotic region corresponds to what in mathematics is called Shilnikov chaos, an unstable manifold that strongly modifies the shape of trajectories and induces highly irregular transient dynamics, even in the absence of noise. The interplay between the Shilnikov chaos and stochastic effects may give rise to some of the complex dynamics observed in neural systems such as transitions between up and down states.
Visual Intelligence and Mood in Visual Communication Design
Authors: Mejía G. Mauricio
Published: September 2013

Human-centered design approaches are intended to provide designers with tools to improve the interaction between design objects and their human users. Often, the design principles of these approaches try to cover broad human requirements, but not particular human differences relevant to use and communication. This paper is a study of visual intelligence and mood as two of the major hypothesized human differences for visual communication design. Evidence shows that visual intelligence predicts adequate interaction patterns and that two dimensions of mood – high tense arousal and anger/frustration – negatively affect the interaction with visual information. The data also suggests that mood change might be negatively associated with interaction experience, showing that mood effects have the potential to be used as a measurement of interaction design quality.
Cyclin B1 mRNA translation is temporally controlled through formation and disassembly of RNA granules
Authors: Kotani Tomoya , Yasuda Kyota , Ota Ryoma , Yamashita Masakane
Published: September 2013

Temporal control of messenger RNA (mRNA) translation is an important mechanism for regulating cellular, neuronal, and developmental processes. However, mechanisms that coordinate timing of translational activation remain largely unresolved. Full-grown oocytes arrest meiosis at prophase I and deposit dormant mRNAs. Of these, translational control of cyclin B1 mRNA in response to maturation-inducing hormone is important for normal progression of oocyte maturation, through which oocytes acquire fertility. In this study, we found that dormant cyclin B1 mRNA forms granules in the cytoplasm of zebrafish and mouse oocytes. Real-time imaging of translation revealed that the granules disassemble at the time of translational activation during maturation. Formation of cyclin B1 RNA granules requires binding of the mRNA to Pumilio1 protein and depends on actin filaments. Disruption of cyclin B1 RNA granules accelerated the timing of their translational activation after induction of maturation, whereas stabilization hindered translational activation. Thus, our results suggest that RNA granule formation is critical for the regulation of timing of translational activation.
The formin FHOD1 and the small GTPase Rac1 promote vaccinia virus actin–based motility
Authors: Alvarez Diego E. , Agaisse Hervé
Published: September 2013

Vaccinia virus dissemination relies on the N-WASP–ARP2/3 pathway, which mediates actin tail formation underneath cell-associated extracellular viruses (CEVs). Here, we uncover a previously unappreciated role for the formin FHOD1 and the small GTPase Rac1 in vaccinia actin tail formation. FHOD1 depletion decreased the number of CEVs forming actin tails and impaired the elongation rate of the formed actin tails. Recruitment of FHOD1 to actin tails relied on its GTPase binding domain in addition to its FH2 domain. In agreement with previous studies showing that FHOD1 is activated by the small GTPase Rac1, Rac1 was enriched and activated at the membrane surrounding actin tails. Rac1 depletion or expression of dominant-negative Rac1 phenocopied the effects of FHOD1 depletion and impaired the recruitment of FHOD1 to actin tails. FHOD1 overexpression rescued the actin tail formation defects observed in cells overexpressing dominant-negative Rac1. Altogether, our results indicate that, to display robust actin-based motility, vaccinia virus integrates the activity of the N-WASP–ARP2/3 and Rac1–FHOD1 pathways.
Sustained Improvement in Hand Hygiene Adherence: Utilizing Shared Accountability and Financial Incentives
Authors: Talbot Thomas R. , Johnson James G. , Fergus Claudette , Domenico John Henry , Schaffner William , Daniels Titus L. , Wilson Greg , Slayton Jennifer , Feistritzer Nancye , Hickson Gerald B.
Published: September 2013

Objective.

To evaluate the impact of an institutional hand hygiene accountability program on healthcare personnel hand hygiene adherence.

Design.

Time-series design with correlation analysis.

Setting.

Tertiary care academic medical center, including outpatient clinics and procedural areas.

Participants.

Medical center healthcare personnel.

Methods.

A comprehensive hand hygiene initiative was implemented in 2 major phases starting in July 2009. Key facets of the initiative included extensive project planning, leadership buy-in and goal setting, financial incentives linked to performance, and use of a system-wide shared accountability model. Adherence was measured by designated hand hygiene observers. Adherence rates were compared between baseline and implementation phases, and monthly hand hygiene adherence rates were correlated with monthly rates of device-associated infection.

Results.

A total of 109,988 observations were completed during the study period, with a sustained increase in hand hygiene adherence throughout each implementation phase (P<.0001) as well as from one phase to the next (P< .0001), such that adherence greater than 85% has been achieved since January 2011. Medical center departments were able to reclaim some rebate dollars allocated through a self-insurance trust, but during the study period, departments did not achieve full reimbursement. Hand hygiene adherence rates were inversely correlated with device-associated standardized infection ratios (R2= 0.70).

Conclusions.

Implementation of this multifaceted, observational hand hygiene program was associated with sustained improvement in hand hygiene adherence. The principles of this program could be applied to other medical centers pursuing improved hand hygiene adherence among healthcare personnel.
Hand Hygiene Behavior: Translating Behavioral Research into Infection Control Practice
Authors: Eiamsitrakoon Thanee , Apisarnthanarak Anucha , Nuallaong Winitra , Khawcharoenporn Thana , Mundy Linda M.
Published: September 2013

Background.

In 2009, the World Health Organization (WHO) recommended “My Five Moments for Hand Hygiene” (5MHH) to optimize hand hygiene (HH). Uptake of these recommendations by healthcare workers (HCWs) remains uncertain.

Methods.

We prospectively observed HCW compliance to 5MHH. After observations, eligible HCWs who consented to interviews completed surveys on factors associated with HH compliance based on constructs from the transtheoretical model of behavioral change (TTM) and the theory of planned behavior (TPB). Survey results were compared with observed HCW behaviors.

Results.

There were 968 observations among 123 HCWs, of whom 110 (89.4%) were female and 63 (51.3%) were nurses. The mean HH compliance for all 5MHH was 23.2% (95% confidence interval [CI], 18.1%-28.3%) by direct observation versus 82.4% (95% CI, 79.9%-84.9%) by self report. The HCW 5MHH compliance was associated with critical care unit encounters (P < .05), medicine unit encounters (P = 0.08, P <.001), immunocompromised patient encounters (P <. 05), and HCW prioritized patient advocacy (P <.001). Self-reported TTM stages of action or maintenance (P = .08) and the total TPB behavior score correlated with observed 5MHH (r = 0.21, P = .02) and with self-reported 5MHH compliance (r = 0.53, P < .001).

Conclusion.

Observed HCW compliance to 5MHH was associated with the type of hospital unit, type of provider-patient encounter, and theory-based behavioral measures of 5MHH commitment.
Mathematical Modeling of Pathogen Trajectory in a Patient Care Environment
Authors: Hewlett Angela L. , Whitney Scott E. , Gibbs Shawn G. , Smith Philip W. , Viljoen Hendrik J.
Published: September 2013

Objective.

Minimizing healthcare worker exposure to airborne infectious pathogens is an important infection control practice. This study utilized mathematical modeling to evaluate the trajectories and subsequent concentrations of particles following a simulated release in a patient care room.

Design.

Observational study.

Setting.

Biocontainment unit patient care room at a university-affiliated tertiary care medical center.

Methods

. Quantitative mathematical modeling of airflow in a patient care room was achieved using a computational fluid dynamics software package. Models were created on the basis of a release of particles from various locations in the room. Computerized particle trajectories were presented in time-lapse fashion over a blueprint of the room. A series of smoke tests were conducted to visually validate the model.

Results.

Most particles released from the head of the bed initially rose to the ceiling and then spread across the ceiling and throughout the room. The highest particle concentrations were observed at the head of the bed nearest to the air return vent, and the lowest concentrations were observed at the foot of the bed.

Conclusions.

Mathematical modeling provides clinically relevant data on the potential exposure risk in patient care rooms and is applicable in multiple healthcare delivery settings. The information obtained through mathematical modeling could potentially serve as an infection control modality to enhance the protection of healthcare workers.
Comparison of Visual versus Microscopic Methods to Detect Blood Splatter from an Intravascular Catheter with Engineered Sharps Injury Protection
Authors: Ansari Aiysha , Ramaiah Padmaja , Collazo Lillian , Salihu Hamisu M. , Haiduven Donna
Published: September 2013

Objective.

To determine whether retractable intravenous devices produced blood splatter and whether blood splatter frequency differed between visual and microscopy detection methods.

Methods.

In this laboratory-based experiment, 105 venipunctures were performed in a simulated brachial vein containing mock venous blood. The retraction mechanism was activated in a testing chamber with precut fabric filters, placed at 3 different locations, to capture blood splatter. Differences in filter mass, visual inspection, and microscopic analysis for presence of blood on filters were the units of analysis. Descriptive statistics, paired Student t tests, and k statistics were used for data analysis.

Results.

Blood splatter was detected visually and microscopically as follows: filter A, 70% and 71%, respectively; filter B, 12% and 9%, respectively; and filter C, 13% and 10%, respectively. A statistically significant difference was observed in the mean mass of filter A between before and after activation when confirmed by the naked eye (P = .014) and microscopically (P = .0092). Substantial agreement between methods was observed for filter A (k = 0.78 [95% confidence interval, 0.64-0.92]), filter B (k = 0.73 [95% confidence interval, 0.51-0.95]), and filter C (k = 0.75 [95% confidence interval, 0.55-0.96]). However, blood was detected by microscopy and not by the naked eye in 7 instances (7%).

Conclusions.

Our findings demonstrate that splatter, which can potentially expose healthcare workers (HCWs) to bloodborne pathogens, is associated with the activation of intravascular catheters with retraction mechanisms. HCWs may not detect this splatter when it occurs and may not report a splash to mucous membranes or nonintact skin. The need to wear personal protective equipment when using such devices is reinforced.
αE-catenin actin-binding domain alters actin filament conformation and regulates binding of nucleation and disassembly factors
Authors: Hansen Scott D. , Kwiatkowski Adam V. , Ouyang Chung-Yueh , Liu HongJun , Pokutta Sabine , Watkins Simon C. , Volkmann Niels , Hanein Dorit , Weis William I. , Mullins R. Dyche , Nelson W. James
Published: September 2013

The actin-binding protein αE-catenin may contribute to transitions between cell migration and cell–cell adhesion that depend on remodeling the actin cytoskeleton, but the underlying mechanisms are unknown. We show that the αE-catenin actin-binding domain (ABD) binds cooperatively to individual actin filaments and that binding is accompanied by a conformational change in the actin protomer that affects filament structure. αE-catenin ABD binding limits barbed-end growth, especially in actin filament bundles. αE-catenin ABD inhibits actin filament branching by the Arp2/3 complex and severing by cofilin, both of which contact regions of the actin protomer that are structurally altered by αE-catenin ABD binding. In epithelial cells, there is little correlation between the distribution of αE-catenin and the Arp2/3 complex at developing cell–cell contacts. Our results indicate that αE-catenin binding to filamentous actin favors assembly of unbranched filament bundles that are protected from severing over more dynamic, branched filament arrays.
From simple to detailed models for cell polarization
Authors: Edelstein-Keshet Leah , Holmes William R. , Zajac Mark , Dutot Meghan
Published: September 2013

Many mathematical models have been proposed for the process of cell polarization. Some of these are ‘functional models’ that capture a class of dynamical behaviour, whereas others are derived from features of signalling molecules. Some mechanistic models are detailed, and therefore complex, whereas others are simplified. Each type contributes to our understanding of cell polarization. However, the huge variety at different levels of detail makes comparisons challenging. Here, we provide examples of both elementary and more detailed models for polarization. We also display how a recent mathematical method, local perturbation analysis, can provide an appropriate tool for such comparisons. This technique simplifies and speeds up the model development process by revealing the effect of model extensions, parameter variations and
in silico
manipulations such as knock-out or over-expression of key molecules. Finally, simulations in both one dimension and two dimensions, and particularly in deforming two-dimensional ‘cells’, can highlight behaviour not captured by traditional simulation methods.
Cell polarity in morphogenesis and metastasis
Authors: Macara Ian G. , McCaffrey Luke
Published: September 2013

Most human cancers arise either from epithelial cells or their progenitors. Epithelial cells possess a distinctive apical–basal polarity and loss of polarity is frequently assumed to be a common feature of cancer progression. In particular, cancer cell dissemination to ectopic sites, and metastatic growth at those sites, is often considered to require a mesenchymal transition in which the transformed epithelial cells lose their apical–basal polarity. However, many cancers retain epithelial characteristics, and until recently there has been little conclusive evidence for an involvement of the cell polarity machinery in tumour growth and metastasis. In this article, we discuss evidence that polarity proteins can be potent invasion suppressors but that loss of epithelial character is not essential either for tumour growth and invasion, or metastatic colonization.