bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatially dependent relative diffusion of nanoparticles in polymer melts
Authors: Yamamoto Umi , Schweizer Kenneth S.
Published: August 2013

We formulate and apply a microscopic statistical-mechanical theory for the non-hydrodynamic relative diffusion coefficient of a pair of spherical nanoparticles in entangled polymer melts based on a combination of Brownian motion, mode-coupling, and polymer physics ideas. The focus is on the mesoscopic regime where particles are larger than the entanglement spacing. The dependence of the non-hydrodynamic friction on interparticle separation, degree of entanglement, and tube diameter is systematically studied. The overall magnitude of the relative diffusivity is controlled by the ratio of the particle to tube diameter and the number of entanglements in a manner reminiscent of single-particle self-diffusion and Stokes-Einstein violations. A rich spatial separation dependence of mobility enhancement relative to the hydrodynamic behavior is predicted even for very large particles, and the asymptotic dependence is derived analytically in the small and large separation limits. Particle separations in excess of 100 nm are sometimes required to recover the hydrodynamic limit. The effects of local polymer-particle packing correlations are found to be weak, and the non-hydrodynamic effects are also small for unentangled melts.
An exact method to obtain effective electrostatic interactions from computer simulations: The case of effective charge amplification
Authors: González-Mozuelos P. , Guerrero-García G. I. , Olvera de la Cruz M.
Published: August 2013

We discuss here an exact method to determine the parameters regulating the screened Coulomb interactions among spherical macroions immersed in a simple electrolyte. This approach provides rigorous definitions for the corresponding screening length, effective permittivity, and renormalized charges, and can be employed for precise and reliable calculations of these parameters within any scheme. In particular, we introduce a simple procedure for extracting this information from computer simulations. The viability of this approach is demonstrated by applying it to a three-component model system which includes anionic nanoparticles and monovalent cations and anions. The mean forces between nanoparticles are determined directly from simulations with two macroions, plus small ions, inside a single cell with periodic boundary conditions. The values of the parameters of interest, on the other hand, are gathered from two separate sets of computer simulations: one set provides information about the short-range correlations among the small ions, which in turn determine the screening length and effective permittivity; the second set supplies the short-range components of the ionic distribution around one isolated macroion, which also determine its renormalized charge. The method presented here thus avoids the uncertain fitting of these parameters from the asymptotic tail of the mean force and allows us to investigate in detail this connection between the renormalized charge of the macroion and the short-range (virtual) part of the ionic cloud surrounding it. Using the standard prescription to extract an effective charge from the corresponding renormalized value, we then proceed to clarify the mechanisms behind the possibility of effective charge amplification (i.e., an effective charge larger than the bare macroion charge). Complementarily, we report results for the corresponding bridge functions too.
Site-site direct correlation functions for three popular molecular models of liquid water
Authors: Zhao Shuangliang , Liu Yu , Liu Honglai , Wu Jianzhong
Published: August 2013

Direct correlation functions (DCFs) play a pivotal role in the applications of classical density functional theory (DFT) to addressing the thermodynamic properties of inhomogeneous systems beyond the local-density or mean-field approximations. Whereas numerous studies have been dedicated to the radial distribution functions of liquid water – the most important solvent on earth, relatively little attention has been given to the site-site DCFs. The water DCFs are long-ranged and difficult to calculate directly by simulation, and the predictions from conventional liquid-state theories have been rarely calibrated. Here we report a computational procedure for accurate evaluation of the site-site DCFs of liquid water based on three popular molecular models (viz., SPC, SPC/E, and TIP3P). The numerical results provide a benchmark for calibration of conventional liquid-state theories and fresh insights into development of new DFT methods. We show that: (1) the long-range behavior of the site-site DCFs depends on both the molecular model and the thermodynamic condition; (2) the asymptotic limit of DCFs at large distance does not follow the mean-spherical approximation (MSA); (3) individual site-site DCFs are long ranged (∼40 nm) but a summation of all DCF pairs exhibits only short-range behavior (∼1 nm or a few water diameters); (4) the site-site bridge correlation functions behave as the DCFs, i.e., they are also long-ranged while the summation of all bridge correlation functions is short ranged. Our analytical and numerical analyses of the DCFs provide some simple strategies for possible improvement of the numerical performance of conventional liquid-state theories.
Interpair electron correlation by second-order perturbative corrections to PNOF5
Authors: Piris M.
Published: August 2013

An antisymmetrized product of strongly orthogonal geminals with the expansion coefficients explicitly expressed by the occupation numbers is used to generate the Piris natural orbital functional 5 (PNOF5). Second-order corrections to PNOF5 are derived and implemented using the multiconfigurational perturbation theory size consistent at second-order (SC2-MCPT). A modified version of the SC2-MCPT including only doubly excited determinants from different geminals is proposed to describe the dispersion interaction in the helium dimer, and to avoid the breakdown of curves in homolytic dissociations of FH, CO, and N2. Comparisons of calculated properties to experimental data are included to verify the accuracy of the formulation.
Numerical study of compressibility effects on the reversed shear Alfvén eigenmode in tokamak plasma
Authors: Yu Limin , Zhang Xianmei , Sheng Zheng-Mao
Published: August 2013

Compressibility effects on the reversed shear Alfvén eigenmode in tokamak plasma are studied numerically. It is shown that compressibility is favorable for the existence of the reversed shear Alfvén eigenmode even without the pressure gradient, and the frequency of the reversed shear Alfvén eigenmode is modified by the geodesic frequency, which is consistent with an analytical theory.
Direct extraction of coherent mode properties from imaging measurements in a linear plasma column
Authors: Light A. D. , Thakur S. C. , Brandt C. , Sechrest Y. , Tynan G. R. , Munsat T.
Published: August 2013

Spectral properties of coherent waves in an argon plasma column are examined using fluctuation data from fast imaging. Visible light from ArII line emission is collected at high frame rates using a high-speed digital camera. A cross-spectral phase technique allows direct visualization of dominant phase structures as a function of frequency, as well as identification of azimuthal asymmetries present in the system. Experimental dispersion estimates are constructed from imaging data alone. Drift-like waves are identified by comparison with theoretical dispersion curves, and a tentative match of a low-frequency spectral feature to Kelvin-Helmholtz-driven waves is presented. Imaging measurements are consistent with previous results, and provide non-invasive, single-shot measurements across the entire plasma cross-section. Implications of the measured spectral properties for imaging measurements of mode dynamics are explored.
An ultrathin and broadband metamaterial absorber using multi-layer structures
Authors: Xiong Han , Hong Jin-Song , Luo Chao-Ming , Zhong Lin-Lin
Published: August 2013

An ultrathin and broadband absorber is investigated in this paper. The metamaterial absorber is composed of a periodic array of loop-dielectric multilayered structure. By tuning the scale factor of the loop and the height of every layer, a desirable refractive index dispersion spectrum is realized, which is the reason to realize a successive anti-reflection in a wide frequency range. The interference mechanism and resonance absorption are identified through analytical derivation and numerical simulations. Numerical results show that the absorption at normal incidence is above 90% in the frequency range of 8.37–21 GHz. Moreover, the structure has a thickness of 3.65 mm (only 0.10λ to 0.26λ at the lowest and highest frequencies, respectively). The explanation to the physical mechanism of the metamaterial absorber is presented and verified.
Easy measurement and analysis method of zeta potential and electrophoretic mobility of water-dispersed colloidal particles by using a self-mixing solid-state laser
Authors: Sudo S. , Ohtomo T. , Otsuka K.
Published: August 2013

We describe a highly sensitive method of measuring electrophoretic mobility and zeta potential of water-dispersed colloidal particles by using a self-mixing laser Doppler velocimeter with a laser-diode-pumped, thin-slice solid-state laser with extremely high optical sensitivity. The power spectra of laser output modulated by reinjected laser light scattered by the electrophoretic particles were observed. The power spectrum cannot be described by the well-known formula for translational motion or flowing Brownian motion, i.e., a combination of Doppler shift, diffusion, and translation. The power spectra shape is found to reflect the velocity distribution of electrophoretic particles in a capillary tube due to the electro-osmotic flow contribution. Not only evaluation of the electrophoretic mobility and zeta potential but also the particle diameter undergoing electrophoretic motion can be performed from the shape of the power spectrum.
Preliminary study of an angiographic and angio-tomographic technique based on K-edge filters
Authors: Golosio Bruno , Oliva Piernicola , Brunetti Antonio , Luca Masala Giovanni , Carpinelli Massimo , Meloni Francesco , Battista Meloni Giovanni
Published: August 2013

Digital Subtraction Angiography is commonly affected by artifacts due to the patient movements during the acquisition of the images without and with the contrast medium. This paper presents a preliminary study on an angiographic and angio-tomographic technique based on the quasi-simultaneous acquisition of two images, obtained using two different filters at the exit of an X-ray tube. One of the two filters (K-edge filter) contains the same chemical element used as a contrast agent (gadolinium in this study). This filter absorbs more radiation with energy just above the so called K-edge energy of gadolinium than the radiation with energy just below it. The other filter (an aluminium filter in this study) is simply used to suppress the low-energy contribution to the spectrum. Using proper calibration curves, the two images are combined to obtain an image of the contrast agent distribution. In the angio-tomographic application of the proposed technique two images, corresponding to the two filter types, are acquired for each viewing angle of the tomographic scan. From the two tomographic reconstructions, it is possible to obtain a three-dimensional map of the contrast agent distribution. The technique was tested on a sample consisting of a rat skull placed inside a container filled with water. Six small cylinders with 4.7 mm internal diameter containing the contrast medium at different concentrations were placed inside the skull. In the plain angiographic application of the technique, five out of six cylinders were visible, with gadolinium concentration down to 0.96%. In the angio-tomographic application, all six cylinders were visible, with gadolinium concentration down to 0.49%. This preliminary study shows that the proposed technique can provide images of the contrast medium at low concentration without most of the artifacts that are present in images produced by conventional techniques. The results encourage further investigation on the feasibility of a clinical implementation of the technique.
Generation of cavitation luminescence by laser-induced exothermic chemical reaction
Authors: Jung Park Han , Diebold Gerald J.
Published: August 2013

Absorption of high power laser radiation by aqueous carbon suspensions is known to result in the formation of highly compressed bubbles of hydrogen and carbon monoxide through the endothermic carbon-steam reaction. The bubbles expand rapidly, overreaching their equilibrium diameter, and then collapse tens to hundreds of microseconds after formation to give a flash of radiation. Here we report on the effects of laser-initiated exothermic chemical reaction on cavitation luminescence. Experiments with hydrogen peroxide added to colloidal carbon suspensions show that both the time of the light flash following the laser pulse and the intensity of luminescence increase with hydrogen peroxide concentration, indicating that large, highly energetic gas bubbles are produced. Additional experiments with colloidal carbon suspensions show the effects of high pressure on the luminescent intensity and its time of appearance following firing of the laser.
First-principles study of band gap engineering of ZnO by alloying with LiGaO2 for ultraviolet applications
Authors: Fang Li Qing , Kuo Jer-Lai
Published: August 2013

Structure and electronic properties of Zn(1-x)(LiGa)(0.5x)O are examined by first-principles methods. The calculations indicate that stable forms of Zn(1−x)(LiGa)(0.5x)O alloys may have different space groups with their parent materials. Our results show the orthorhombic lattices with Pm, Pmn21, and P1 structures have lower formation energies than the wurtzite lattices at a given (LiGa)0.5 composition. The band-gap energies of Zn(1−x)(LiGa)(0.5x)O in the wurtzite and orthorhombic structure are nearly identical and all compounds have direct band gaps. The gap widens as the (LiGa)0.5 concentration increases due to a weaker hybridization of O2 p and Zn 3d and stronger bonding–antibonding interaction between Zn 4 s (Ga 4 s, Li 2 s) and O 2p. Zn(1-x)(LiGa)(0.5x)O alloys have potential for applications such as ultraviolet (UV) light emitting devices and highly sensitive UV detectors to replace Zn1-xMgxO and Zn1-xBexO alloys due to the stable lattice structures and low band gap bowing.
Black tungsten for solar power generation
Authors: Ungaro Craig , Gray Stephen K. , Gupta Mool C.
Published: August 2013

The viability of micro/nano textured tungsten as an efficient solar absorber is explored via computational electrodynamics simulations. Pseudo-random structures are investigated, along with the effects of protective oxide coatings. These structures show extremely high absorption across the solar spectrum along with relaxed requirements for manufacturing, allowing them to be applied for power generation.
Solution-processed zinc-indium-tin oxide thin-film transistors for flat-panel displays
Authors: Kim Bo Sung , Taek Jeong Yeon , Lee Doohyoung , Choi TaeYoung , Jung Seung-Ho , Whan Choi June , Yang Chanwoo , Jo Kangmoon , Lee Byung-ju , Park Eunhye , Na Kim Doo , Kim Youngmin , Shin Sungtae
Published: August 2013

Highly uniform thin-films of zinc-indium-tin oxide (ZITO) semiconductors were formed using solution process with wet-annealing at a low temperature of 250 °C. The solution-processed ZITO thin-film transistors with a top-gate staggered structure were fabricated to exhibit field-effect mobility of 2.04 ± 0.28 cm2/Vs at saturation region, threshold voltage (Vth) of 2.15 ± 0.75 V, subthreshold slope of 0.27 ± 0.14 V/dec. and excellent reliability (ΔVth = −4.35 V) for negative bias temperature illumination stress. Based on the performance, a 10.1 in. full-color liquid crystal display was demonstrated by the optimized full photolithography process.
Engineering electromagnetic responses of bilayered metamaterials based on Fano resonances
Authors: Shi Jinhui , Liu Ran , Na Bo , Xu Yiqun , Zhu Zheng , Wang Yuekun , Ma Huifeng , Cui Tiejun
Published: August 2013

We numerically and experimentally demonstrate engineered electromagnetic responses from a single-peak Fano resonance to a fast roll-off behavior by using planar metamaterials, which are constructed by bilayered asymmetrically split rings (ASRs) with twist angles of 0° and 180°. Since each single-layer ASR metamaterial reveals a Fano-type resonance, the dramatic transmission properties are resulted from the hybridization of electromagnetic resonances due to the near-field coupling between two Fano resonances and the far-field retardation effect of the bilayered metamaterials. The surface currents and charges distributions provide an insight into deep understanding of in-phase and out-of-phase coupling of two Fano resonances. The measured and simulated results of bilayered metamaterials agree well to each other. Especially, the proposed metamaterials can be exploited to design metamaterial-based devices in the THz and optical ranges like filters and sensors.
Enhanced light extraction of Bi3Ge4O12 scintillator by graded-refractive-index antireflection coatings
Authors: Tong Fei , Liu Bo , Chen Hong , Zhu Zhichao , Gu Mu
Published: August 2013

A three-layer graded-refractive-index antireflection coating is designed and prepared on the one surface of the Bi3Ge4O12 scintillator by sol-gel technology. The emission intensity of the Bi3Ge4O12 with a graded-refractive-index antireflection coating exhibits a broadband and omnidirectional enhancement of 15.9% compared with the reference sample without coating. This significant enhancement is attributed to the decrease of Fresnel reflection, which is consistent with the measurement of transmission spectra. Additionally, it is evident that the graded-refractive-index coating is superior to the conventional quarter-wave coating due to the omnidirectionality advantage.
Depth Effect on Lightness Revisited: The Role of Articulation, Proximity and Fields of Illumination
Authors: Radonjić Ana , Gilchrist Alan L.
Published: August 2013

The coplanar ratio principle proposes that when the luminance range in an image is larger than the canonical reflectance range of 30:1, the lightness of a target surface depends on the luminance ratio between that target and its adjacent coplanar neighbor (Gilchrist, 1980). This conclusion is based on experiments in which changes in the perceived target depth produced large changes in its perceived lightness without significantly altering the observers' retinal image. Using the same paradigm, we explored how this depth effect on lightness depends on display complexity (articulation), proximity of the target to its highest coplanar luminance and spatial distribution of fields of illumination. Importantly, our experiments allowed us to test differing predictions made by the anchoring theory (Gilchrist et al., 1999), the coplanar ratio principle, as well as other models. We report three main findings, generally consistent with anchoring theory predictions: (1) Articulation can substantially increase the depth effect. (2) Target lightness depends not on the adjacent luminance but on the highest coplanar luminance, irrespective of its position relative to the target. (3) When a plane contains multiple fields of illumination, target lightness depends on the highest luminance in its field of illumination, not on the highest coplanar luminance.
e-Mental health in South Australia: impact of age, gender and region of residence
Authors: Keane Miriam C. , Roeger Leigh S. , Allison Stephen , Reed Richard L.
Published: August 2013

Respondents to the 2008 South Australian Health Omnibus survey (n = 2996) indicated whether, in the previous 12 months, they had searched for information on the Internet relating to emotional issues such as depression, anxiety or relationship problems. Logistic regression was used to examine the penetration of e-mental health in rural and metropolitan areas (region of residence), and determine if other demographic variables (age group, gender) also impacted on the likelihood of an individual reporting that they had used the Internet to obtain such information. Overall, 9% of respondents reported that they had used the Internet for this purpose. The multivariate model was significant, F(11, 2985) = 4.82, P < 0.0001, with middle-aged rural females most likely to report doing so (18.1%), whereas older rural males were least likely to report doing so (2.2.%). These findings have important implications for the design of e-mental health promotional programs that provide information and interventions to improve mental health.
Soil texture and salinity effects on calibration of TDR300 dielectric moisture sensor
Authors: Kargas George , Ntoulas Nikolaos , Nektarios Panayiotis A.
Published: August 2013

Newly developed sensors have simplified real-time determination of soil water content (θm). Although the TDR300 is one of the most recent dielectric sensors, little is known with regard to the accuracy and dependency of its measurements of soil type and other environmental factors. In this study, the performance of TDR300 was investigated using liquids of known dielectric properties and a set of porous media with textures ranging from sandy to clayey. The experiments were conducted in the laboratory by mixing different amounts of water with each soil to obtain a sufficient range of soil water contents. For sand, the calculated permittivity values (εr) correlated adequately with Topp’s equation derived for time domain reflectometry. However, for the remaining inorganic porous media, εr values were overestimated compared with those resulting from Topp’s equation, especially for water contents exceeding 0.2 cm3/cm3. The results suggested that the relationship between θm and √εr was strongly linear (0.953< r2 <0.998). The most accurate results were provided by soil-specific calibration equations, which were obtained by the multi-point calibration equation. However, two-point calibration equations determined water content in all tested soils reasonably well, except for clay soil. A linear regression equation was developed that correlated the slope of the relationship θm–√εr with bulk soil electrical conductivity (EC). The regression slope was influenced more by soil EC than by soil texture. Also, TDR300 response was investigated in bi-layered systems (liquid–air and saturated porous media–air). In a bi-layered sensing volume characterised by strongly contrasting dielectric values, the appropriate bulk permittivity values for water and loam soil were determined by arithmetic rather than refractive index averaging, while for butanol and sand these values remained somewhere between the two averaging schemes, indicating that the upward infiltration calibration technique is inappropriate for the TDR300 sensor. Soil solute EC, as determined by measurements conducted in liquids and sand, significantly affected permittivity values at much lower levels than the limit of EC <2 dS/m, as suggested by the manufacturer. However, the relationship θm–√εr remained linear up to EC 2 dS/m, which corresponded to a bulk soil EC value of 0.6 dS/m. By contrast, for EC values >2 dS/m, the relationship θm–√εr was not linear, and, thus the TDR300 device calibration became increasingly difficult. Therefore, rather than operating as a time domain device, TDR300 operates as a water content reflectometer type device.
Interleukin-1 receptor antagonist prevents murine bronchopulmonary dysplasia induced by perinatal inflammation and hyperoxia
Authors: Nold Marcel F. , Mangan Niamh E. , Rudloff Ina , Cho Steven X. , Shariatian Nikeh , Samarasinghe Thilini D. , Skuza Elizabeth M. , Pedersen John , Veldman Alex , Berger Philip J. , Nold-Petry Claudia A.
Published: August 2013

Bronchopulmonary dysplasia (BPD) is a common lung disease of premature infants, with devastating short- and long-term consequences. The pathogenesis of BPD is multifactorial, but all triggers cause pulmonary inflammation. No therapy exists; therefore, we investigated whether the anti-inflammatory interleukin-1 receptor antagonist (IL-1Ra) prevents murine BPD. We precipitated BPD by perinatal inflammation (lipopolysaccharide injection to pregnant dams) and rearing pups in hyperoxia (65% or 85% O
2
). Pups were treated daily with IL-1Ra or vehicle for up to 28 d. Vehicle-injected animals in both levels of hyperoxia developed a severe BPD-like lung disease (alveolar number and gas exchange area decreased by up to 60%, alveolar size increased up to fourfold). IL-1Ra prevented this structural disintegration at 65%, but not 85% O
2
. Hyperoxia depleted pulmonary immune cells by 67%; however, extant macrophages and dendritic cells were hyperactivated, with CD11b and GR1 (Ly6G/C) highly expressed. IL-1Ra partially rescued the immune cell population in hyperoxia (doubling the viable cells), reduced the percentage that were activated by up to 63%, and abolished the unexpected persistence of IL-1α and IL-1β on day 28 in hyperoxia/vehicle-treated lungs. On day 3, perinatal inflammation and hyperoxia each triggered a distinct pulmonary immune response, with some proinflammatory mediators increasing up to 20-fold and some amenable to partial or complete reversal with IL-1Ra. In summary, our analysis reveals a pivotal role for IL-1α/β in murine BPD and an involvement for MIP (macrophage inflammatory protein)-1α and TREM (triggering receptor expressed on myeloid cells)-1. Because it effectively shields newborn mice from BPD, IL-1Ra emerges as a promising treatment for a currently irremediable disease that may potentially brighten the prognosis of the tiny preterm patients.
isomiRID: a framework to identify microRNA isoforms
Authors: de Oliveira Luiz Felipe Valter , Christoff Ana Paula , Margis Rogerio
Published: August 2013

Summary: MicroRNAs (miRNAs) have been extensively studied owing to their important regulatory roles in genic expression. An increasingly number of reports are performing extensive data mining in small RNA sequencing libraries to detect miRNAs isoforms and also 5′ and 3′ post-transcriptional nucleotide additions, as well as edited miRNAs sequences. A ready to use pipeline, isomiRID, was developed to standardize and automatize the search for miRNAs isoforms in high-throughput small RNA sequencing libraries.

Availability: isomiRID is a command line Python script available at http://www.ufrgs.br/RNAi/isomiRID/.

Contact:  rogerio.margis@ufrgs.br

Supplementary information:  Supplementary Date are available at Bioinformatics online.
omiRas: a Web server for differential expression analysis of miRNAs derived from small RNA-Seq data
Authors: Müller Sören , Rycak Lukas , Winter Peter , Kahl Günter , Koch Ina , Rotter Björn
Published: August 2013

Summary: Small RNA deep sequencing is widely used to characterize non-coding RNAs (ncRNAs) differentially expressed between two conditions, e.g. healthy and diseased individuals and to reveal insights into molecular mechanisms underlying condition-specific phenotypic traits. The ncRNAome is composed of a multitude of RNAs, such as transfer RNA, small nucleolar RNA and microRNA (miRNA), to name few. Here we present omiRas, a Web server for the annotation, comparison and visualization of interaction networks of ncRNAs derived from next-generation sequencing experiments of two different conditions. The Web tool allows the user to submit raw sequencing data and results are presented as: (i) static annotation results including length distribution, mapping statistics, alignments and quantification tables for each library as well as lists of differentially expressed ncRNAs between conditions and (ii) an interactive network visualization of user-selected miRNAs and their target genes based on the combination of several miRNA–mRNA interaction databases.

Availability and Implementation: The omiRas Web server is implemented in Python, PostgreSQL, R and can be accessed at: http://tools.genxpro.net/omiras/.

Contact:  rotter@genxpro.de

Supplementary Information:  Supplementary data are available at Bioinformatics online.
Radio properties of the magnetar near Sagittarius A* from observations with the Australia Telescope Compact Array
Authors: Shannon R. M. , Johnston S.
Published: August 2013

We have carried out observations of the newly discovered magnetar in the direction of Sagittarius A* using the Australia Telescope Compact Array (ATCA) in four frequency bands from 4.5 to 20 GHz. Radio pulsations are clearly detected at all frequencies. We measure the pulsar's dispersion measure to be 1650 ± 50 cm−3 pc, the highest of any of the known pulsars. Once Faraday rotation has been taken into account, the pulse profile is more than 80 per cent linearly polarized at all frequencies and has a small degree (5 per cent) of circular polarization. The rotation measure of −67000 ± 500 rad m−2 is the largest (in magnitude) ever measured for a pulsar but still a factor of 8 smaller than Sgr A* itself. The combination of the dispersion and rotation measures implies an integrated magnetic field strength of −50 μG along the line of sight. The flux density appears to have increased by about a factor of 2 between observations made 30 d apart. This object therefore joins the small class of radio emitting magnetars.
Managerial Miscalibration*
Authors: Ben-David Itzhak , Graham John R. , Harvey Campbell R.
Published: August 2013

Using a unique 10-year panel that includes more than 13,300 expected stock market return probability distributions, we find that executives are severely miscalibrated, producing distributions that are too narrow: realized market returns are within the executives’ 80% confidence intervals only 36% of the time. We show that executives reduce the lower bound of the forecast confidence interval during times of high market uncertainty; however, ex post miscalibration is worst during periods of high uncertainty. We also find that executives who are miscalibrated about the stock market show similar miscalibration regarding their own firms’ prospects. Finally, firms with miscalibrated executives seem to follow more aggressive corporate policies: investing more and using more debt financing.
Cell-Specific Transcriptional Profiling Reveals Candidate Mechanisms Regulating Development and Function of Uterine Epithelia in Mice
Authors: Filant Justyna , Spencer Thomas E.
Published: August 2013

All mammalian uteri have luminal (LE) and glandular epithelia (GE) in their endometrium. The LE mediates uterine receptivity and blastocyst attachment for implantation, and the GE synthesize and secrete or transport bioactive substances involved in blastocyst implantation, uterine receptivity, and stromal cell decidualization. However, the mechanisms governing uterine epithelial development after birth and their function in the adult are not fully understood. Here, comprehensive microarray analysis was conducted on LE and GE isolated by laser capture microdissection from uteri on Postnatal Day 10 (PD 10) and day of pseudopregnancy (DOPP) 2.5 and 3.5. This data was integrated with analysis of uteri from gland-containing control and aglandular progesterone-induced uterine gland knockout mice from PD 10 and DOPP 3.5. Many genes were expressed in both epithelia, but there was greater expression of genes in the LE than in the GE. In the neonate, GE-expressed genes were enriched for morphogenesis, development, migration, and retinoic acid signaling. In the adult, LE-expressed genes were enriched for metabolic processes and steroid biosynthesis, whereas retinoid signaling, tight junction, extracellular matrix, and regulation of kinase activity were enriched in the GE. The transcriptome differences in the epithelia support the idea that each cell type has a distinct and complementary function in the uterus. The candidate genes and regulatory networks identified here provide a framework to discover new mechanisms regulating development of epithelia in the postnatal uterus and their functions in early pregnancy.
Pathophysiology of neonatal acute bacterial meningitis
Authors: Barichello Tatiana , Fagundes Glauco D. , Generoso Jaqueline S. , Elias Samuel Galvão , Simões Lutiana R. , Teixeira Antonio Lucio
Published: August 2013

Neonatal meningitis is a severe acute infectious disease of the central nervous system and an important cause of morbidity and mortality worldwide. The inflammatory reaction involves the meninges, the subarachnoid space and the brain parenchymal vessels and contributes to neuronal injury. Neonatal meningitis leads to deafness, blindness, cerebral palsy, seizures, hydrocephalus or cognitive impairment in approximately 25–50 % of survivors. Bacterial pathogens can reach the blood–brain barrier and be recognized by antigen-presenting cells through the binding of Toll-like receptors. They induce the activation of NFκB or mitogen-activated protein kinase pathways and subsequently upregulate leukocyte populations and express numerous proteins involved in inflammation and the immune response. Many brain cells can produce cytokines, chemokines and other pro-inflammatory molecules in response to bacterial stimuli, and polymorphonuclear leukocytes are attracted, activated and released in large amounts of superoxide anion and nitric oxide, leading to peroxynitrite formation and generating oxidative stress. This cascade leads to lipid peroxidation, mitochondrial damage and breakdown of the blood–brain barrier, thus contributing to cell injury during neonatal meningitis. This review summarizes information on the pathophysiology and adjuvant treatment of acute bacterial meningitis in neonates.
Difference in Abscisic Acid Perception Mechanisms between Closure Induction and Opening Inhibition of Stomata
Authors: Yin Ye , Adachi Yuji , Ye Wenxiu , Hayashi Maki , Nakamura Yoshimasa , Kinoshita Toshinori , Mori Izumi C. , Murata Yoshiyuki
Published: August 2013

Abscisic acid (ABA) induces stomatal closure and inhibits light-induced stomatal opening. The mechanisms in these two processes are not necessarily the same. It has been postulated that the ABA receptors involved in opening inhibition are different from those involved in closure induction. Here, we provide evidence that four recently identified ABA receptors (PYRABACTIN RESISTANCE1 [PYR1], PYRABACTIN RESISTANCE-LIKE1 [PYL1], PYL2, and PYL4) are not sufficient for opening inhibition in Arabidopsis (Arabidopsis thaliana). ABA-induced stomatal closure was impaired in the pyr1/pyl1/pyl2/pyl4 quadruple ABA receptor mutant. ABA inhibition of the opening of the mutant’s stomata remained intact. ABA did not induce either the production of reactive oxygen species and nitric oxide or the alkalization of the cytosol in the quadruple mutant, in accordance with the closure phenotype. Whole cell patch-clamp analysis of inward-rectifying K+ current in guard cells showed a partial inhibition by ABA, indicating that the ABA sensitivity of the mutant was not fully impaired. ABA substantially inhibited blue light-induced phosphorylation of H+-ATPase in guard cells in both the mutant and the wild type. On the other hand, in a knockout mutant of the SNF1-related protein kinase, srk2e, stomatal opening and closure, reactive oxygen species and nitric oxide production, cytosolic alkalization, inward-rectifying K+ current inactivation, and H+-ATPase phosphorylation were not sensitive to ABA.
Literacy components model for at‐risk young adults enrolled in career and technical education
Authors: Mellard Daryl F. , Woods Kari L. , McJunkin Linette
Published: August 2013

Little is known about literacy skills of an important adult population: educationally and economically disadvantaged young adults. This exploratory study used principal components analysis of 33 measures of reading subskills, spelling, maths, memory and other cognitive processes among 335 at‐risk 16‐ to 24‐year‐olds enrolled in a career and technical education programme. The analysis yielded a five‐component model explaining 69% of the variance in the data. Most of this variance was attributed to two components: element and word skills (including spelling) and language comprehension (including vocabulary). Using these components, models predicting two performance criterion measures yielded different results. A model using all five components predicted 51% of functional reading measured by the Comprehensive Adult Student Assessment System. A three‐component model with element and word skills, language comprehension and processing speed predicted 55% of variance in reading comprehension measured by the Test of Adult Basic Education. Implications of these findings for further research are discussed.
Crisis Politics in Authoritarian Regimes: How Crises Catalyse Changes under the State–Society Interactive Framework
Authors: Chan Hin‐yeung
Published: August 2013

Most studies and research on crisis management and government crises focus on nations that are advanced and democratic. Through the institutionalized mechanism of voting, the public can respond to a government's handling of a crisis without destabilizing the democratic system of government. However, the consequences of crises, particularly governance crises, in authoritarian regimes have not been adequately addressed. Drawing upon different frameworks in the field, this paper proposes a heuristic crisis development ladder and a state–society interactive framework more relevant for studying crisis management in authoritarian nations such as China. By focusing on the catalytic effect of crisis that accelerates reforms and changes, this paper argues that critical crises are politically powerful and decisive in authoritarian systems, especially in the context of an increasingly proactive civil society. This paper illustrates the crisis provoking politics that influences decision‐making under non‐democratic rule.
Liver X receptor activation increases hepatic fatty acid desaturation by the induction of SCD1 expression through an LXRα‐SREBP1c‐dependent mechanism (肝X受体活化可通过LXRα‐SREBP1c依赖的机制诱导SCD1表达来增加肝脏脂肪酸不饱和度)
Authors: Zhang Xiaoyan , Liu Jia , Su Wen , Wu Jing , Wang Chunjiong , Kong Xiaomu , Gustafsson Jan‐Åke , Ding Jie , Ma Xiaosong , Guan Youfei
Published: August 2013

Background

Liver X receptors (LXRs) including LXRα and LXRβ are members of the nuclear hormone receptor superfamily of ligand activated transcription factors, which serve as lipid sensors to regulate expression of genes controlling many aspects of cholesterol and fatty acid metabolism. The liver is the central organ in controlling lipid metabolism. In the present study, we aimed at elucidating the role of LXR activation in hepatic fatty acid homeostasis.

Methods

We treated C57BL/6 mice with a synthetic non‐selective LXR agonist TO901317. Fatty acid profile of lipid esters in the livers was analyzed by gas‐liquid chromatography. Real‐time polymerase chain reaction (PCR) and western blot were used to determine the expression of SREBP1c and SCD1 in TO901317‐treated livers and HepG2 cells.

Results

Oral administration of TO901317 resulted in increased fatty acid desaturation in the liver, with concomitant increase in hepatic stearoyl CoA desaturase‐1 (SCD1) expression. TO901317‐induced SCD1 expression was observed in LXRβ‐/‐ mice, but not in LXRα‐/‐ mice. Furthermore, TO901317 significantly increased expression of sterol regulatory element‐binding protein 1c (SREBP1c), the deficiency of which almost completely abolished the induction of SCD1 by TO901317. This drug induced both SREBP1c and SCD1 expression in HepG2 cells. Overexpression of SREBP1c resulted in a significant increase in SCD1 promoter activity and expression.

Conclusions

Taken together, the present studies demonstrate that pan‐LXR activation increases hepatic fatty acid desaturation via the induction of SCD1 expression in an LXRα‐dependent and SREBP1c‐mediated manner.
Exposure (mAs) optimisation of a multi‐detector CT protocol for hepatic lesion detection: Are thinner slices better?
Authors: Dobeli Karen Leigh , Lewis Sarah Jane , Meikle Steven Richard , Thiele David Lewis , Brennan Patrick Christopher
Published: August 2013

Introduction

The purpose of this work was to determine the exposure‐optimised slice thickness for hepatic lesion detection with CT.

Methods

A phantom containing spheres (diameter 9.5, 4.8 and 2.4 mm) with CT density 10 HU below the background (50 HU) was scanned at 125, 100, 75 and 50 mAs. Data were reconstructed at 5‐, 3‐ and 1‐mm slice thicknesses. Noise, contrast‐to‐noise ratio (CNR), area under the curve (AUC) as calculated using receiver operating characteristic analysis and sensitivity representing lesion detection were calculated and compared.

Results

Compared with the 125 mAs/5 mm slice thickness setting, significant reductions in AUC were found for 75 mAs (P < 0.01) and 50 mAs (P < 0.05) at 1‐ and 3‐mm thicknesses, respectively; sensitivity for the 9.5‐mm sphere was significantly reduced for 75 (P < 0.05) and 50 mAs (P < 0.01) at 1‐mm thickness; sensitivity for the 4.8‐mm sphere was significantly lower for 100, 75 and 50 mAs at all three slice thicknesses (P < 0.05). The 2.4‐mm sphere was rarely detected. At each slice thickness, noise at 100, 75 and 50 mAs exposures was approximately 10, 30 and 50% higher, respectively, than that at 125 mAs exposure. CNRs decreased in an irregular manner with reductions in exposure and slice thickness.

Conclusion

This study demonstrated no advantage to using slices below 5 mm thickness, and consequently thinner slices are not necessarily better.
Reflections on a participatory documentary process: constructing territorial histories of dispossession among Afro‐descendant youth in Colombia
Authors: Vélez‐Torres Irene
Published: August 2013

This paper seeks to discuss the use of a participatory documentary process (PDP) in human geography as a method of constructing critical visual information on territorial histories of dispossession. The process was also used to enhance social change both in conjunction with local communities and within the communities themselves. The project involved 14 local young participants and four professionals who collectively produced a documentary on the rural context of violence in La Toma District, Colombia. By enabling the reflections and intentions of young participants in the research process, PDP gave special value to their social and political commitment to supporting community social organisation, and provided fresh research insights into comprehending territorial conflict. The paper concludes that this method amplifies participatory and action research approaches in geography by producing knowledge that is academically and socially relevant. Such collective, emancipatory and anti‐hegemonic visual representations and actions for social change in PDP are especially pertinent in spaces of conflict and violence.
‘Running a studio's a silly business’: work and employment in the contemporary recording studio sector
Authors: Watson Allan
Published: August 2013

This paper is concerned with work and employment in the recording studio sector of the contemporary musical economy. More specifically, it aims to begin to address the lack of attention paid to the issue of individual subjectivity in the cultural workplace, through an empirically informed account of how the changing economic conditions in the recording studio sector are impacting on work as seen from the perspective of those working in the sector. The sector is one marked by a continued move towards more temporary and flexible forms of project working, as seen in the comparatively recent development of a freelance project‐based model for recording. For record producers and studio engineers, these developments have impacted negatively on employment relations, working conditions and job security. Recent developments in digital technologies, which have resulted in a crisis of reproduction in the musical economy, have further heightened the importance of these issues. Drawing on qualitative interviews with record producers and engineers working in recording studios in London, the paper highlights how the rise of freelance work has resulted in a precarious work environment that has shifted the pressure of obtaining work, and the financial risk of not doing so, on to individual producers and engineers, and at the same time resulted in exhausting yet bulimic work regimes. Both for new and experienced producers and engineers, the sector is revealed as an increasingly difficult one in which to find and maintain gainful employment; for many, it is an increasingly exploitive one. Yet, the individuality afforded to producers and engineers by digital technologies, and the potential symbolic and financial rewards on offer to those who can successfully follow a career in music production, means that it remains an attractive and much sought‐after career.
Variations in landform definition: a quantitative assessment of differences between five maps of glacial cirques in the Ţarcu Mountains (Southern Carpathians, Romania)
Authors: Ardelean Florina , Drăguţ Lucian , Urdea Petru , Török‐Oance Marcel
Published: August 2013

Geomorphological mapping is an important tool in geomorphology and related disciplines, yet it depends on the expertise and experience of the practitioner. The reliability of the technique and its products has not been subject to sufficient quantitative evaluation. In this study, we evaluated the magnitudes of differences in mapping glacial cirques between five maps in a mountainous area in the Southern Carpathians in Romania and attempted to identify the causes of the differences observed and possible solutions for obtaining more objective geomorphological mapping. We found notable differences between maps (in paired sample comparisons in all cases for the total values in each dataset) in the number of cirques, the total area and in headwall crest lengths. Statistically significant differences were found between datasets based on different semantic models of glacial cirques. Differences in mapping arise mainly from differences in conceptualising glacial cirques. When mapping relied on an explicit semantic model (a geomorphometric approach), differences were significantly smaller. Therefore, explicit semantic models of landforms based on land surface variables can result in more similar maps and further facilitate the transition from manual delineation to automated recognition of landforms from Digital Elevation Models (DEMs).
Homeless people and the city of abstract machines: Assemblage thinking and the performative approach to homelessness
Authors: Lancione Michele
Published: August 2013

The paper focuses on one central point of the ‘performative’ approach to homelessness that is still inadequately explored by the current literature: the conceptualisation of the relational entanglements between homeless people and the city. The argument is that only through a critical attention to these fluid and more‐than‐human details will we be able to re‐imagine a different politics of homelessness. The paper, engaging with the work of Deleuze and Guattari as well as with critical assemblages thinking, proposes two concepts that are considered to be fundamental in this sense. First, assemblage, as a concept able to render the hybrid constituency of the individual within the city; and second, abstract machines, as a way to take into account the fluidity of power in affecting one's own experience of homelessness. The approach proposed in the paper is illustrated through the presentations of original ethnographic material derived from ten months of ethnographic fieldwork in Turin, Italy. The paper concludes by suggesting that the abstract machine of homelessness can be tackled in at least two ways. First, re‐working the institutional assemblages of care that produce stigmatising discourses and deep emotional effects. Second, liberating homeless people's capacities and resources, which are currently poorly accounted by canonical literature and policies.