bluuebunny/crossref_metadata_2025 huggingface dataset:
Lingual Propulsive Pressures Across Consistencies Generated by the Anteromedian and Posteromedian Tongue by Healthy Young Adults
Authors: Gingrich Laura L. , Stierwalt Julie A. G. , Hageman Carlin F. , LaPointe Leonard L.
Published: January 2012

Purpose

In the present study, the authors investigated lingual propulsive pressures generated in the normal swallow by the anterior and posterior lingual segments for various consistencies and maximum isometric tasks.

Method

Lingual pressures for saliva, thin, and honey-thick liquid boluses were measured via the Iowa Oral Performance Instrument (IOPI Medical, Carnation, WA) at both anteromedian and posteromedian lingual segments of 62 healthy participants, ages 18–34 years (30 men, 32 women).

Results

A repeated-measures analysis of variance revealed that all lingual swallowing pressures were significantly greater at the anteromedian segment than at the posteromedian segment. Gender was not a significant factor; however, women exhibited greater swallowing pressures across all conditions. Lingual pressures increased as bolus viscosity increased. No significant interactions existed. Analysis of a subset of 30 participants revealed that men exhibited greater maximal isometric pressure at the anteromedian segment than women, with no significant gender difference at the posteromedian segment. A significantly higher percentage of maximum isometric tongue pressure was exerted by the posteromedian tongue than by the anteromedian tongue.

Conclusion

Findings suggest that greater amplitudes of lingual pressures are generated during normal swallowing at the anteromedian lingual segment; however, a greater percentage of maximum isometric tongue pressure was exerted by the posteromedian lingual segment, suggesting increased effort by the posterior tongue during bolus propulsion.
The Effect of Tongue Exercise on Serotonergic Input to the Hypoglossal Nucleus in Young and Old Rats
Authors: Behan Mary , Moeser Adam E. , Thomas Cathy F. , Russell John A. , Wang Hao , Leverson Glen E. , Connor Nadine P.
Published: January 2012

Purpose

Breathing and swallowing problems affect elderly people and may be related to age-associated tongue dysfunction. Hypoglossal motoneurons that innervate the tongue receive a robust, excitatory serotonergic (5HT) input and may be affected by aging. We used a rat model of aging and progressive resistance tongue exercise to determine whether age-related alterations in 5HT inputs to the hypoglossal nucleus can be modified. We hypothesized that tongue forces would increase with exercise, 5HT input to the tongue would decrease with age, and tongue exercise would augment 5HT input to the hypoglossal nucleus.

Method

Young (9–10 months), middle-aged (24–25 months), and old (32–33 months) male F344/BN rats received tongue exercise for 8 weeks. Immunoreactivity for 5HT was measured in digital images of sections through the hypoglossal nucleus using ImageJ software.

Results

Tongue exercise resulted in increased maximum tongue forces at all ages. There was a statistically significant increase in 5HT immunoreactivity in the hypoglossal nucleus in exercised, young rats but only in the caudal third of the nucleus and primarily in the ventral half.

Conclusion

Specificity found in serotonergic input following exercise may reflect the topographic organization of motoneurons in the hypoglossal nucleus and the tongue muscles engaged in the exercise paradigm.
Using Video Modeling Intervention and Speech Generating Devices To Teach Requesting Behaviors to Persons With Autism
Authors: Copple Karen , Koul Rajinder , Banda Devender , Frye Ellen
Published: January 2012

One of the instructional techniques reported in the literature to teach communication skills to persons with autism is video modeling (VM). VM is a form of observational learning that involves watching and imitating the desired target behavior(s) exhibited by the person on the videotape. VM has been used to teach a variety of social and communicative behaviors to persons with developmental disabilities such as autism. In this paper, we describe the VM technique and summarize the results of two single-subject experimental design studies that investigated the acquisition of spontaneous requesting skills using a speech generating device (SGD) by persons with autism following a VM intervention. The results of these two studies indicate that a VM treatment package that includes a SGD as one of its components can be effective in facilitating communication in individuals with autism who have little or no functional speech.
Experimentally investigation of the CCD binning option in particle imaging velocimetry measurements of laminar flows
Authors: Akselli B. , Teke I.
Published: January 2012

In this work we present an experimental investigation of the employment usage application of the vertical pixel binning (PB) option for PIV (particle image velocimetry) measurements. The PB option increases the speed of a CCD, at the cost of loosing spatial resolution. Consequently, it is expected that PB will positively impact the dynamic velocity range of the PIV measurements. In order to show the benefit of the CCD PB option in PIV measurements, we have carried out series of microPIV experiments on laminar flows, seeded with 1 μm fluorescent polystyrene microparticles and passing through a 200 μm × 200 μm × 50000μm microchannel. The flow images were recorded at normal, 2 × 1, and 3 × 1 vertical PB modes of a monochrome CCD camera. The experimentally obtained velocity profiles were calculated using the ensemble-averaged cross-correlation method and Gaussian sup-pixel interpolation and then compared with theoretically calculated velocity profiles. We found that the error introduced by the PB option did not exceed the inherent uncertainty of the PIV system used. For a particular PIV system CCD camera, using the PB option allowed an increase in the dynamic velocity range of a PIV system by more than a factor of two, without extra investments.
The Control of Hyperglycemia in Alloxan Treated Diabetic Mice through the Stimulation of Hepatic Insulin Synthesis due to the Production of Nitric Oxide
Authors: Ghosh R. , Jana P. , Sinha A.
Published: January 2012

The hepatocytes from the adult mice when stimulated by glucose had been reported to synthesize and secrete insulin. The feasibility of controlling hyperglycemia in alloxan induced diabetic mice through hepatic synthesis of insulin was studied.

Insulin synthesis was determined by in vitro translation of mRNA and by immunohistochemistry of the hepatocytes and assayed by enzyme linked immunosorbent assay (ELISA). Dermcidin isoform 2 (dermcidin) was measured by ELISA. Nitric oxide was measured by methemoglobin method. Insulin synthesis was quantitated by immunoblot technique and the expression of proinsulin genes I and II in the hepatocytes was quantitated by cDNA synthesis

It was found that in contrast to normal hepatocytes, the hepatocytes from the diabetic mice showed impaired insulin synthesis in the presence of glucose that was related to the inhibition of nitric oxide synthesis through the synthesis of dermcidin, a potent competitive inhibitor of nitric oxide synthase. The increase of systemic NO synthesis either by oral use of 0.7 mM acetyl salicylic acid (aspirin) or by dermal application of 0.28 mmol sodium nitroprusside in saline soaked in cotton pad was found to decrease blood glucose level from 600 mg/dL to 120 mg/dL with concomitant increase of plasma insulin level from 5 µunits/dL to 38 µunits/dL. And subsequently normalized dermcidin level from 80 nM to 4.5 nM within 24 h (p<0.001; n=10).

Our studies suggested the possibility of controlling hyperglycemia in alloxan induced diabetic mice by the stimulation of the hepatic insulin synthesis through the systemic stimulation of NO production in the hepatocytes.
Fast magneto-optical spectrometry by spectrometer
Authors: Du G. X. , Saito S. , Takahashi M.
Published: January 2012

Time efficient measurement of the spectroscopic magneto-optical (MO) activity of materials has always been desirable. In conventional MO systems, the monochromator produces quasi-monochromatic light in a narrow wavelength window. Therefore, to measure the spectroscopic MO activity, a large number of measurements over the full spectra is required to obtain satisfactory wavelength resolution and thus is very time consuming. Here, we develop a novel system that is capable of fast measurement of the MO activity by only one white light source, two polarizers, one achromatic quarter-wave plate, and one spectrometer. This system is flexible from UV to IR region, only depending on the power spectra of light source and sensitivity of the detector at the corresponding wavelengths. As examples, we measured the intriguing optic and MO activity in glass, ferromagnetic thin film, and bulk GaAs in the visible to near infrared region. The results of glass demonstrated a minimum resolvable Faraday rotation angle of 0.004° by the currently equipped system.
Four degree of freedom liquid dispenser for direct write capillary self-assembly with sub-nanoliter precision
Authors: Beroz Justin , Bedewy Mostafa , Reinker Michael , Chhajer Vipul , Awtar Shorya , Hart A. John
Published: January 2012

Capillary forces provide a ubiquitous means of organizing micro- and nanoscale structures on substrates. In order to investigate the mechanism of capillary self-assembly and to fabricate complex ordered structures, precise control of the meniscus shape is needed. We present a precision instrument that enables deposition of liquid droplets spanning from 2 nl to 300 μl, in concert with mechanical manipulation of the liquid-substrate interface with four degrees of freedom. The substrate has sub-100 nm positioning resolution in three axes of translation, and its temperature is controlled using thermoelectric modules. The capillary tip can rotate about the vertical axis while simultaneously dispensing liquid onto the substrate. Liquid is displaced using a custom bidirectional diaphragm pump, in which an elastic membrane is hydraulically actuated by a stainless steel syringe. The syringe is driven by a piezoelectric actuator, enabling nanoliter volume and rate control. A quantitative model of the liquid dispenser is verified experimentally, and suggests that compressibility in the hydraulic line deamplifies the syringe stroke, enabling sub-nanoliter resolution control of liquid displacement at the capillary tip. We use this system to contact-print water and oil droplets by mechanical manipulation of a liquid bridge between the capillary and the substrate. Finally, we study the effect of droplet volume and substrate temperature on the evaporative self-assembly of monodisperse polymer microspheres from sessile droplets, and demonstrate the formation of 3D chiral assemblies of micro-rods by rotation of the capillary tip during evaporative assembly.
An energy decomposition analysis for intermolecular interactions from an absolutely localized molecular orbital reference at the coupled-cluster singles and doubles level
Authors: Azar R. Julian , Head-Gordon Martin
Published: January 2012

We propose a wave function-based method for the decomposition of intermolecular interaction energies into chemically-intuitive components, isolating both mean-field- and explicit correlation-level contributions. We begin by solving the locally-projected self-consistent field for molecular interactions equations for a molecular complex, obtaining an intramolecularly polarized reference of self-consistently optimized, absolutely-localized molecular orbitals (ALMOs), determined with the constraint that each fragment MO be composed only of atomic basis functions belonging to its own fragment. As explicit inter-electronic correlation is integral to an accurate description of weak forces underlying intermolecular interaction potentials, namely, coordinated fluctuations in weakly interacting electronic densities, we add dynamical correlation to the ALMO polarized reference at the coupled-cluster singles and doubles level, accounting for explicit dispersion and charge-transfer effects, which map naturally onto the cluster operator. We demonstrate the stability of energy components with basis set extension, follow the hydrogen bond-breaking coordinate in the Cs-symmetry water dimer, decompose the interaction energies of dispersion-bound rare gas dimers and other van der Waals complexes, and examine charge transfer-dominated donor-acceptor interactions in borane adducts. We compare our results with high-level calculations and experiment when possible.
Nuclear motion captured by the slow electron velocity imaging technique in the tunnelling predissociation of the S1 methylamine
Authors: Ahn Doo-Sik , Lee Jeongmook , Choon Park Young , Sup Lee Yoon , Kyu Kim Sang
Published: January 2012

Predissociation dynamics of methylamines (CH3NH2 and CH3ND2) on the first electronically excited states are studied using the slow-electron velocity imaging method to unravel the multi-dimensional nature of the N–H(D) chemical bond dissociation reaction which occurs via tunnelling. The nearly free internal rotation around the C–N bond axis is found to be strongly coupled to the reaction pathway, revealing nuclear motions actively involved in the tunnelling process on the S1 potential energy surfaces. The vibrational state-resolved energy and angular distributions of photoelectron, ejected from the ionization mediated by the metastable intermediate S1 state provide a unique way for mapping the predissociative potential energy surfaces.
On the polarized emission from exciton complexes in GaN quantum dots
Authors: Amloy S. , Karlsson K. F. , Andersson T. G. , Holtz P. O.
Published: January 2012

The optical linear polarization properties of exciton complexes in asymmetric Stranski-Krastanov grown GaN quantum dots have been investigated experimentally and theoretically. It is demonstrated that the polarization angle and the polarization degree can be conveniently employed to associate emission lines in the recorded photoluminescence spectra to a specific dot. The experimental results are in agreement with configuration interaction computations, which predict similar polarization degrees for the exciton and the biexciton (within 10%) in typical GaN quantum dots. The theory further predicts that the polarization degree can provide information about the charge state of the dot.
Work-function-tuned multilayer graphene as current spreading electrode in blue light-emitting diodes
Authors: Chandramohan S. , Hye Kang Ji , Katharria Y. S. , Han Nam , Seon Beak Yun , Bok Ko Kang , Bae Park Jong , Kyu Kim Hyun , Suh Eun-Kyung , Hong Chang-Hee
Published: January 2012

This letter reports on the implementation of multilayer graphene (MLG) as a current spreading electrode in GaN-based blue light-emitting diodes. We demonstrate two facile strategies to maneuver the electrical coupling between p-GaN layer and MLG. Using a work-function-tuned MLG and a thin gold (Au) metal interlayer, the current spreading and thus the device forward voltage are considerably improved. We attribute these improvements to the diminution in work function difference between p-GaN and MLG, the decrease of specific contact resistance, and the enhancement in the conductivity of MLG film as a result of doping. In addition, rapid thermal annealing at elevated temperature is found to provide additional pathway for enhanced carrier injection.
Noncatalytic chemical vapor deposition of graphene on high-temperature substrates for transparent electrodes
Authors: Sun Jie , Cole Matthew T. , Lindvall Niclas , Teo Kenneth B. K. , Yurgens August
Published: January 2012

A noncatalytic chemical vapor deposition mechanism is proposed, where high precursor concentration, long deposition time, high temperature, and flat substrate are needed to grow large-area nanocrystalline graphene using hydrocarbon pyrolysis. The graphene is scalable, uniform, and with controlled thickness. It can be deposited on virtually any nonmetallic substrate that withstands ∼1000 °C. For typical examples, graphene grown directly on quartz and sapphire shows transmittance and conductivity similar to exfoliated or metal-catalyzed graphene, as evidenced by transmission spectroscopy and transport measurements. Raman spectroscopy confirms the sp2-C structure. The model and results demonstrate a promising transfer-free technique for transparent electrode production.
Tuning the Schottky barrier height at MgO/metal interface
Authors: Jaouen T. , Jézéquel G. , Delhaye G. , Lépine B. , Turban P. , Schieffer P.
Published: January 2012

We present an experimental investigation of the interface electronic structure of thin MgO films epitaxially grown on Ag(001) by x-ray and ultraviolet photoemission spectroscopy as a function of the oxide growth conditions. It is shown that the Schottky barrier height at MgO/metal interface can be tuned over 0.7 eV by a modification of the oxygen partial pressure or the sample temperature. These experimental results are explained in the framework of the extended Schottky-Mott model and the MgO-induced polarization effect by Mg enrichment of the silver surface region.
Effects of scandium on the bandgap and location of Ce3+ levels in Lu1−xScxBO3:Ce scintillators
Authors: Wu Yuntao , Ren Guohao , Ding Dongzhou , Yang Fan , Pan Shangke
Published: January 2012

Transparent Lu1−xScxBO3:Ce (x = 0.3, 0.5, 0.7, 0.8) scintillation crystals were grown by Czochralski method. Vacuum ultraviolet excitation spectra and thermoluminescence glow curves revealed the narrowing of bandgap and the redshift of the first electric dipole-allowed fd transition of Ce3+ with the increase of Sc content. The ionization energy evaluated from the photoluminescence decays as a function of temperature indicated that, with increasing Sc content, the thermal ionization probability occurring from 5d1 relaxed state of Ce3+ was enhanced, which degraded the scintillation efficiency of Lu1−xScxBO3:Ce crystals.
An ultrashort-duration, high-repetition-rate pulse source for laser ionization/mass spectrometry
Authors: Uchimura T. , Nakamura N. , Imasaka T.
Published: January 2012

This paper describes a sample inlet system with several advantages over other pulsed valves, as applied to resonance-enhanced multiphoton ionization/time-of-flight mass spectrometry. The nozzle is based on online concentration by analyte adsorption/laser desorption (online COLD), where a capillary column with a narrowly synthesized tip is employed for sample introduction. The analyte molecules adsorbed at the tip are desorbed by a pulsed laser and are injected into a mass spectrometer as a packet. The online COLD nozzle can produce very short gas pulses on the order of 1 μs. Moreover, this nozzle is capable of operating over a wide range of repetition rates from 1 Hz to 1 kHz. In addition, this nozzle intrinsically possesses several unique characteristics; for instance, it can be heated to very high temperatures and has nearly zero dead volume. Therefore, the present sample introduction technique offers an ideal and versatile nozzle for laser ionization/mass spectrometry.
Ultrafast dynamics of the Mn3+ d-d transition and spin-lattice interaction in YMnO3 film
Authors: Jin Zuanming , Ma Hong , Li Gaofang , Xu Yue , Ma Guohong , Cheng Zhenxiang
Published: January 2012

We investigate the photo-induced carrier dynamics and spin-lattice interaction in hexagonal YMnO3 film by the temperature-dependent femtosecond pump-probe spectroscopy. The spin-lattice interaction is identified from the slow component of the transient transmittance change with the excitation energies tuned to 1.7 eV and 2.0 eV, which are close to Mn3+ ions d(xz),(yz)→d(z2) and d(x2-y2),(xy)→d(z2) transition, respectively. Temperature dependences of the spin-lattice relaxation parameters demonstrate that the spin-lattice interaction is strongly connected with the d-d transition within Mn3+ ions and enhanced by spin ordering.
Nutritional and flock management options to reduce methane output and methane per unit product from sheep enterprises
Authors: Hegarty R. S. , Alcock D. , Robinson D. L. , Goopy J. P. , Vercoe P. E.
Published: January 2012

The daily methane output of sheep is strongly affected by the quantity and digestibility of feed consumed. There are few widely applicable technologies that reduce the methane output of grazing ruminants without limiting feed intake per head or animal numbers. In contrast, there are many opportunities to increase the amount of animal product generated per unit of feed eaten. These include improving growth and reproductive rates of livestock and will reduce methane emission per unit of product (called emissions intensity) for individual animals. Producer responses to such improvements through changes to stocking rate and total area grazed will have a major effect on the total emission and profitability of the enterprise. First mating of ewes as lambs (~7 months of age) rather than as hoggets (~19 months of age) reduces the emissions intensity of self-replacing flocks but not that of flocks for which replacement ewes are purchased. Selection of sheep for improved residual feed intake reduces emissions intensity at the individual animal level as well as at the enterprise level. At present, emissions policies that motivate farm managers to consider generating fewer emissions rather than more profit or product are lacking.
Measuring fabric handle to define luxury: an overview of handle specification in next-to-skin knitted fabrics from Merino wool
Authors: Mahar T. J. , Wang H.
Published: January 2012

An examination is presented of the relevance of luxury to the wool textile and garment supply chain. This examination leads to a review of the concept and importance of fabric handle as a means of defining important aspects of fabric quality. Examples are given for woven fabrics of the general relationships between subjectively assessed fabric handle attributes such as fabric softness and smoothness and measured low stress, generally high deformation, fabric properties such as fabric bending rigidity and extensibility. A brief overview is presented of the development of a system for predicting a set of subjectively assessed handle attributes for next-to-skin knitted fabrics from measurable fabric properties. Seven handle attributes selected by experienced assessors as being important for defining tactile sensations associated with next-to-skin knitted fabrics were: fabric smoothness, hairiness, softness, tightness, dryness, warmth and weight. Subjective assessments on a 1–10 scale of these seven attributes, plus an assessment of overall handle, were conducted by 12 experienced assessors on 74 next-to-skin knitted fabrics. The precision of the mean assessment of the 12 assessors ranged between 0.8 and 1.1, indicating that there was sufficient consensus on key fabric handle assessments to justify development of a method for predicting them from measurements of the physical properties of fabrics. All fabrics were tested using the PhabrOmeter fabric evaluation system, which records the force exerted during insertion of a fabric into and through an orifice. Geometric parameters were derived to describe the PhabrOmeter force-displacement curve results, and statistical models were developed to predict the average handle assessments of the 12 assessors. The precision of the models in predicting the handle intensities of eight fabric attributes on an independent validation set of 22 fabrics was significantly better than the precision of an individual assessor (confidence limits = 1.4–2.6 and 2.5–3.8, for predicted and assessed ratings, respectively). A case is made that this technology has the potential to assist in the growth of new markets for Merino wool products.
Opportunities for genetic improvement of lamb survival
Authors: Brien F. D. , Hebart M. L. , Smith D. H. , Edwards J. E. Hocking , Greeff J. C. , Hart K. W. , Refshauge G. , Bird-Gardiner T. L. , Gaunt G. , Behrendt R. , Robertson M. W. , Hinch G. N. , Geenty K. G. , van der Werf J. H. J.
Published: January 2012

Data on lamb survival and associated traits involving records from 15 192 lambs, 6308 dams and 284 sires from the Sheep CRC’s Information Nucleus were studied. Lamb survival to 3 days of age and to weaning was 85 and 80%, respectively, and heritability (±s.e.) was 0.014 ± 0.010 and 0.010 ± 0.010, respectively. Of the 14 traits recorded at birth, time taken for the lamb to bleat, rectal temperature and crown–rump length had the highest genetic correlations with lamb survival to weaning (–0.43 ± 0.32, 0.56 ± 0.33 and –0.38 ± 0.36, respectively). Under selection for a multi-trait objective including net reproduction rate (but not lamb survival), survival was predicted to decline genetically by 0.25 lambs weaned per 100 lambs born.year, although this was reversed to a gain of 0.20 lambs weaned per 100 lambs born.year by including the trait in the breeding objective and using 50 half-sib and 50 progeny records per selection candidate. Accuracy of selection for lamb survival was improved to 0.735 with a selection index of lamb survival to weaning, lamb ease, birth coat score, time taken to bleat, rectal temperature and crown–rump length, with the addition of 50 half-sibs and 50 progeny records per candidate. Our results suggest that unless actively incorporated into breeding objectives, lamb survival may genetically decline; however, gains are possible with direct selection using half-sib and progeny records. The addition of indirect selection criteria for lamb survival can further improve accuracy, up to 93.4%, but requires further investigation.
Betacellulin promotes cell proliferation in the neural stem cell niche and stimulates neurogenesis
Authors: Gómez-Gaviro María Victoria , Scott Charlotte E. , Sesay Abdul K. , Matheu Ander , Booth Sarah , Galichet Christophe , Lovell-Badge Robin
Published: January 2012

Neural stem cells (NSCs) reside in specialized niches in the adult mammalian brain, including the subventricular zone and the dentate gyrus, which act to control NSC behavior. Among other cell types within these niches, NSCs are found in close proximity to blood vessels. We carried out an analysis of the interaction between endothelial cells and NSCs, and show that betacellulin (BTC), a member of the EGF family and one of several signaling molecules made by the former, induces NSC proliferation and prevents spontaneous differentiation in culture. When infused into the lateral ventricle, BTC induces expansion of NSCs and neuroblasts, and promotes neurogenesis in the olfactory bulb and dentate gyrus, whereas specific blocking antibodies reduce the number of stem/progenitor cells. BTC-null mice are less able to regenerate neuroblast numbers compared with WT littermates following depletion of proliferating cells using cytosine-β-
d
-arabinofuranoside. BTC acts via both the EGF receptor, located on NSCs, and ErbB4, located on neuroblasts, with the latter explaining why its effects are distinct from those of EGF itself. Our results suggest that BTC could be a good candidate to aid regenerative therapies.
Brain structure in healthy adults is related to serum transferrin and the H63D polymorphism in theHFEgene
Authors: Jahanshad Neda , Kohannim Omid , Hibar Derrek P. , Stein Jason L. , McMahon Katie L. , de Zubicaray Greig I. , Medland Sarah E. , Montgomery Grant W. , Whitfield John B. , Martin Nicholas G. , Wright Margaret J. , Toga Arthur W. , Thompson Paul M.
Published: January 2012

Control of iron homeostasis is essential for healthy central nervous system function: iron deficiency is associated with cognitive impairment, yet iron overload is thought to promote neurodegenerative diseases. Specific genetic markers have been previously identified that influence levels of transferrin, the protein that transports iron throughout the body, in the blood and brain. Here, we discovered that transferrin levels are related to detectable differences in the macro- and microstructure of the living brain. We collected brain MRI scans from 615 healthy young adult twins and siblings, of whom 574 were also scanned with diffusion tensor imaging at 4 Tesla. Fiber integrity was assessed by using the diffusion tensor imaging-based measure of fractional anisotropy. In bivariate genetic models based on monozygotic and dizygotic twins, we discovered that partially overlapping additive genetic factors influenced transferrin levels and brain microstructure. We also examined common variants in genes associated with transferrin levels,TFandHFE, and found that a commonly carried polymorphism (H63D at rs1799945) in the hemochromatoticHFEgene was associated with white matter fiber integrity. This gene has a well documented association with iron overload. Our statistical maps reveal previously unknown influences of the same gene on brain microstructure and transferrin levels. This discovery may shed light on the neural mechanisms by which iron affects cognition, neurodevelopment, and neurodegeneration.
Osmotic spreading of
Bacillus subtilis
biofilms driven by an extracellular matrix
Authors: Seminara Agnese , Angelini Thomas E. , Wilking James N. , Vlamakis Hera , Ebrahim Senan , Kolter Roberto , Weitz David A. , Brenner Michael P.
Published: January 2012

Bacterial biofilms are organized communities of cells living in association with surfaces. The hallmark of biofilm formation is the secretion of a polymeric matrix rich in sugars and proteins in the extracellular space. In
Bacillus subtilis
, secretion of the exopolysaccharide (EPS) component of the extracellular matrix is genetically coupled to the inhibition of flagella-mediated motility. The onset of this switch results in slow expansion of the biofilm on a substrate. Different strains have radically different capabilities in surface colonization: Flagella-null strains spread at the same rate as wild type, while both are dramatically faster than EPS mutants. Multiple functions have been attributed to the EPS, but none of these provides a physical mechanism for generating spreading. We propose that the secretion of EPS drives surface motility by generating osmotic pressure gradients in the extracellular space. A simple mathematical model based on the physics of polymer solutions shows quantitative agreement with experimental measurements of biofilm growth, thickening, and spreading. We discuss the implications of this osmotically driven type of surface motility for nutrient uptake that may elucidate the reduced fitness of the matrix-deficient mutant strains.
Decoupling of deforestation and soy production in the southern Amazon during the late 2000s
Authors: Macedo Marcia N. , DeFries Ruth S. , Morton Douglas C. , Stickler Claudia M. , Galford Gillian L. , Shimabukuro Yosio E.
Published: January 2012

From 2006 to 2010, deforestation in the Amazon frontier state of Mato Grosso decreased to 30% of its historical average (1996–2005) whereas agricultural production reached an all-time high. This study combines satellite data with government deforestation and production statistics to assess land-use transitions and potential market and policy drivers associated with these trends. In the forested region of the state, increased soy production from 2001 to 2005 was entirely due to cropland expansion into previously cleared pasture areas (74%) or forests (26%). From 2006 to 2010, 78% of production increases were due to expansion (22% to yield increases), with 91% on previously cleared land. Cropland expansion fell from 10 to 2% of deforestation between the two periods, with pasture expansion accounting for most remaining deforestation. Declining deforestation coincided with a collapse of commodity markets and implementation of policy measures to reduce deforestation. Soybean profitability has since increased to pre-2006 levels whereas deforestation continued to decline, suggesting that antideforestation measures may have influenced the agricultural sector. We found little evidence of direct leakage of soy expansion into cerrado in Mato Grosso during the late 2000s, although indirect land-use changes and leakage to more distant regions are possible. This study provides evidence that reduced deforestation and increased agricultural production can occur simultaneously in tropical forest frontiers, provided that land is available and policies promote the efficient use of already-cleared lands (intensification) while restricting deforestation. It remains uncertain whether government- and industry-led policies can contain deforestation if future market conditions favor another boom in agricultural expansion.
Homeostatic plasticity mechanisms are required for juvenile, but not adult, ocular dominance plasticity
Authors: Ranson Adam , Cheetham Claire E. J. , Fox Kevin , Sengpiel Frank
Published: January 2012

Ocular dominance (OD) plasticity in the visual cortex is a classic model system for understanding developmental plasticity, but the visual cortex also shows plasticity in adulthood. Whether the plasticity mechanisms are similar or different at the two ages is not clear. Several plasticity mechanisms operate during development, including homeostatic plasticity, which acts to maintain the total excitatory drive to a neuron. In agreement with this idea, we found that an often-studied substrain of C57BL/6 mice, C57BL/6JOlaHsd (6JOla), lacks both the homeostatic component of OD plasticity as assessed by intrinsic signal imaging and synaptic scaling of mEPSC amplitudes after a short period of dark exposure during the critical period, whereas another substrain, C57BL/6J (6J), exhibits both plasticity processes. However, in adult mice, OD plasticity was identical in the 6JOla and 6J substrains, suggesting that adult plasticity occurs by a different mechanism. Consistent with this interpretation, adult OD plasticity was normal in TNFα knockout mice, which are known to lack juvenile synaptic scaling and the homeostatic component of OD plasticity, but was absent in adult α-calcium/calmodulin-dependent protein kinase II;T286A (αCaMKII
T286A
) mice, which have a point mutation that prevents autophosphorylation of αCaMKII. We conclude that increased responsiveness to open-eye stimulation after monocular deprivation during the critical period is a homeostatic process that depends mechanistically on synaptic scaling during the critical period, whereas in adult mice it is mediated by a different mechanism that requires αCaMKII autophosphorylation. Thus, our study reveals a transition between homeostatic and long-term potentiation–like plasticity mechanisms with increasing age.
The take-it-or-leave-it option allows small penalties to overcome social dilemmas
Authors: Sasaki Tatsuya , Brännström Åke , Dieckmann Ulf , Sigmund Karl
Published: January 2012

Self-interest frequently causes individuals engaged in joint enterprises to choose actions that are counterproductive. Free-riders can invade a society of cooperators, causing a tragedy of the commons. Such social dilemmas can be overcome by positive or negative incentives. Even though an incentive-providing institution may protect a cooperative society from invasion by free-riders, it cannot always convert a society of free-riders to cooperation. In the latter case, both norms, cooperation and defection, are stable: To avoid a collapse to full defection, cooperators must be sufficiently numerous initially. A society of free-riders is then caught in a social trap, and the institution is unable to provide an escape, except at a high, possibly prohibitive cost. Here, we analyze the interplay of (a) incentives provided by institutions and (b) the effects of voluntary participation. We show that this combination fundamentally improves the efficiency of incentives. In particular, optional participation allows institutions punishing free-riders to overcome the social dilemma at a much lower cost, and to promote a globally stable regime of cooperation. This removes the social trap and implies that whenever a society of cooperators cannot be invaded by free-riders, it will necessarily become established in the long run, through social learning, irrespective of the initial number of cooperators. We also demonstrate that punishing provides a “lighter touch” than rewarding, guaranteeing full cooperation at considerably lower cost.
High-yield maize with large net energy yield and small global warming intensity
Authors: Grassini Patricio , Cassman Kenneth G.
Published: January 2012

Addressing concerns about future food supply and climate change requires management practices that maximize productivity per unit of arable land while reducing negative environmental impact. On-farm data were evaluated to assess energy balance and greenhouse gas (GHG) emissions of irrigated maize in Nebraska that received large nitrogen (N) fertilizer (183 kg of N⋅ha
−1
) and irrigation water inputs (272 mm or 2,720 m
3
ha
−1
). Although energy inputs (30 GJ⋅ha
−1
) were larger than those reported for US maize systems in previous studies, irrigated maize in central Nebraska achieved higher grain and net energy yields (13.2 Mg⋅ha
−1
and 159 GJ⋅ha
−1
, respectively) and lower GHG-emission intensity (231 kg of CO
2
e⋅Mg
−1
of grain). Greater input-use efficiencies, especially for N fertilizer, were responsible for better performance of these irrigated systems, compared with much lower-yielding, mostly rainfed maize systems in previous studies. Large variation in energy inputs and GHG emissions across irrigated fields in the present study resulted from differences in applied irrigation water amount and imbalances between applied N inputs and crop N demand, indicating potential to further improve environmental performance through better management of these inputs. Observed variation in N-use efficiency, at any level of applied N inputs, suggests that an N-balance approach may be more appropriate for estimating soil N
2
O emissions than the Intergovernmental Panel on Climate Change approach based on a fixed proportion of applied N. Negative correlation between GHG-emission intensity and net energy yield supports the proposition that achieving high yields, large positive energy balance, and low GHG emissions in intensive cropping systems are not conflicting goals.
Quasi-liquid layers on ice crystal surfaces are made up of two different phases
Authors: Sazaki Gen , Zepeda Salvador , Nakatsubo Shunichi , Yokomine Makoto , Furukawa Yoshinori
Published: January 2012

Ice plays crucially important roles in various phenomena because of its abundance on Earth. However, revealing the dynamic behavior of quasi-liquid layers (QLLs), which governs the surface properties of ice crystals at temperatures near the melting point, remains an experimental challenge. Here we show that two types of QLL phases appear that exhibit different morphologies and dynamics. We directly visualized the two types of QLLs on ice crystal surfaces by advanced optical microscopy, which can visualize the individual 0.37-nm-thick elementary steps on ice crystal surfaces. We found that they had different stabilities and different interactions with ice crystal surfaces. The two immiscible QLL phases appeared heterogeneously, moved around, and coalesced dynamically on ice crystal surfaces. This picture of surface melting is quite different from the conventional picture in which one QLL phase appears uniformly on ice crystal surfaces.
Systematic identification of interactions between host cell proteins and E7 oncoproteins from diverse human papillomaviruses
Authors: White Elizabeth A. , Sowa Mathew E. , Tan Min Jie Alvin , Jeudy Sheila , Hayes Sebastian D. , Santha Sreevidya , Münger Karl , Harper J. Wade , Howley Peter M.
Published: January 2012

More than 120 human papillomaviruses (HPVs) have now been identified and have been associated with a variety of clinical lesions. To understand the molecular differences among these viruses that result in lesions with distinct pathologies, we have begun a MS-based proteomic analysis of HPV–host cellular protein interactions and have created the plasmid and cell line libraries required for these studies. To validate our system, we have characterized the host cellular proteins that bind to the E7 proteins expressed from 17 different HPV types. These studies reveal a number of interactions, some of which are conserved across HPV types and others that are unique to a single HPV species or HPV genus. Binding of E7 to UBR4/p600 is conserved across all virus types, whereas the cellular protein ENC1 binds specifically to the E7s from HPV18 and HPV45, both members of genus alpha, species 7. We identify a specific interaction of HPV16 E7 with ZER1, a substrate specificity factor for a cullin 2 (CUL2)-RING ubiquitin ligase, and show that ZER1 is required for the binding of HPV16 E7 to CUL2. We further show that ZER1 is required for the destabilization of the retinoblastoma tumor suppressor RB1 in HPV16 E7-expressing cells and propose that a CUL2–ZER1 complex functions to target RB1 for degradation in HPV16 E7-expressing cells. These studies refine the current understanding of HPV E7 functions and establish a platform for the rapid identification of virus–host interactions.
Structural basis for membrane targeting by the MVB12-associated β-prism domain of the human ESCRT-I MVB12 subunit
Authors: Boura Evzen , Hurley James H.
Published: January 2012

MVB12-associated β-prism (MABP) domains are predicted to occur in a diverse set of membrane-associated bacterial and eukaryotic proteins, but their existence, structure, and biochemical properties have not been characterized experimentally. Here, we find that the MABP domains of the MVB12A and B subunits of ESCRT-I are functional modules that bind in vitro to liposomes containing acidic lipids depending on negative charge density. The MABP domain is capable of autonomously localizing to subcellular puncta and to the plasma membrane. The 1.3-Å atomic resolution crystal structure of the MVB12B MABP domain reveals a β-prism fold, a hydrophobic membrane-anchoring loop, and an electropositive phosphoinositide-binding patch. The basic patch is open, which explains how it senses negative charge density but lacks stereoselectivity. These observations show how ESCRT-I could act as a coincidence detector for acidic phospholipids and protein ligands, enabling it to function both in protein transport at endosomes and in cytokinesis and viral budding at the plasma membrane.
Hypoxic regulation of the cerebral microcirculation is mediated by a carbon monoxide-sensitive hydrogen sulfide pathway
Authors: Morikawa Takayuki , Kajimura Mayumi , Nakamura Tomomi , Hishiki Takako , Nakanishi Tsuyoshi , Yukutake Yoshinori , Nagahata Yoshiko , Ishikawa Mami , Hattori Katsuji , Takenouchi Toshiki , Takahashi Takao , Ishii Isao , Matsubara Kazuko , Kabe Yasuaki , Uchiyama Shinichiro , Nagata Eiichiro , Gadalla Moataz M. , Snyder Solomon H. , Suematsu Makoto
Published: January 2012

Enhancement of cerebral blood flow by hypoxia is critical for brain function, but signaling systems underlying its regulation have been unclear. We report a pathway mediating hypoxia-induced cerebral vasodilation in studies monitoring vascular disposition in cerebellar slices and in intact mouse brains using two-photon intravital laser scanning microscopy. In this cascade, hypoxia elicits cerebral vasodilation via the coordinate actions of H2S formed by cystathionine β-synthase (CBS) and CO generated by heme oxygenase (HO)-2. Hypoxia diminishes CO generation by HO-2, an oxygen sensor. The constitutive CO physiologically inhibits CBS, and hypoxia leads to increased levels of H2S that mediate the vasodilation of precapillary arterioles. Mice with targeted deletion of HO-2 or CBS display impaired vascular responses to hypoxia. Thus, in intact adult brain cerebral cortex of HO-2–null mice, imaging mass spectrometry reveals an impaired ability to maintain ATP levels on hypoxia.
Activation-induced cytidine deaminase (AID)-dependent somatic hypermutation requires a splice isoform of the serine/arginine-rich (SR) protein SRSF1
Authors: Kanehiro Yuichi , Todo Kagefumi , Negishi Misaki , Fukuoka Junji , Gan Wenjian , Hikasa Takuya , Kaga Yoshiaki , Takemoto Masayuki , Magari Masaki , Li Xialu , Manley James L. , Ohmori Hitoshi , Kanayama Naoki
Published: January 2012

Somatic hypermutation (SHM) of Ig variable region (
IgV
) genes requires both
IgV
transcription and the enzyme activation-induced cytidine deaminase (AID). Identification of a cofactor responsible for the fact that
IgV
genes are much more sensitive to AID-induced mutagenesis than other genes is a key question in immunology. Here, we describe an essential role for a splice isoform of the prototypical serine/arginine-rich (SR) protein SRSF1, termed SRSF1-3, in AID-induced SHM in a DT40 chicken B-cell line. Unexpectedly, we found that SHM does not occur in a DT40 line lacking SRSF1-3 (DT40-ASF), although it is readily detectable in parental DT40 cells. Strikingly, overexpression of AID in DT40-ASF cells led to a large increase in nonspecific (off-target) mutations. In contrast, introduction of SRSF1-3, but not SRSF1, into these cells specifically restored SHM without increasing off-target mutations. Furthermore, we found that SRSF1-3 binds preferentially to the
IgV
gene and inhibits processing of the
Ig
transcript, providing a mechanism by which SRSF1-3 makes the
IgV
gene available for AID-dependent SHM. SRSF1 not only acts as an essential splicing factor but also regulates diverse aspects of mRNA metabolism and maintains genome stability. Our findings, thus, define an unexpected and important role for SRSF1, particularly for its splice variant, in enabling AID to function specifically on its natural substrate during SHM.
Digoxin inhibits development of hypoxic pulmonary hypertension in mice
Authors: Abud Edsel M. , Maylor Julie , Undem Clark , Punjabi Arjun , Zaiman Ari L. , Myers Allen C. , Sylvester J. T. , Semenza Gregg L. , Shimoda Larissa A.
Published: January 2012

Chronic hypoxia is an inciting factor for the development of pulmonary arterial hypertension. The mechanisms involved in the development of hypoxic pulmonary hypertension (HPH) include hypoxia-inducible factor 1 (HIF-1)–dependent transactivation of genes controlling pulmonary arterial smooth muscle cell (PASMC) intracellular calcium concentration ([Ca
2+
]
i
) and pH. Recently, digoxin was shown to inhibit HIF-1 transcriptional activity. In this study, we tested the hypothesis that digoxin could prevent and reverse the development of HPH. Mice were injected daily with saline or digoxin and exposed to room air or ambient hypoxia for 3 wk. Treatment with digoxin attenuated the development of right ventricle (RV) hypertrophy and prevented the pulmonary vascular remodeling and increases in PASMC [Ca
2+
]
i
, pH, and RV pressure that occur in mice exposed to chronic hypoxia. When started after pulmonary hypertension was established, digoxin attenuated the hypoxia-induced increases in RV pressure and PASMC pH and [Ca
2+
]
i
. These preclinical data support a role for HIF-1 inhibitors in the treatment of HPH.