bluuebunny/crossref_metadata_2025 huggingface dataset:
Photoresponse mechanisms of ultraviolet photodetectors based on colloidal ZnO quantum dot-graphene nanocomposites
Authors: Ick Son Dong , Yeon Yang Hee , Whan Kim Tae , Il Park Won
Published: January 2013

Ultraviolet (UV) photodetectors were fabricated using the wet spin-coating for ZnO quantum dots (QDs) and the transfer method for the graphene sheet. High-resolution transmission electron microscopy images showed that the ZnO QDs were uniformly distributed between the voids of the surface circumferences on the graphene layers. Current-voltage measurements on the UV photodetector at 300 K showed that the ratio of the photocurrent to the dark current was about 1.1 × 104. The rise and the decay times of the UV photodetector were approximately 2 and 1 s, respectively. The photoresponse mechanisms are described on the basis of the experimental results.
Metamaterial-based half Maxwell fish-eye lens for broadband directive emissions
Authors: Dhouibi Abdallah , Nawaz Burokur Shah , de Lustrac André , Priou Alain
Published: January 2013

The broadband directive emission from a metamaterial surface is numerically and experimentally reported. The metasurface, composed of non-resonant complementary closed ring structures, is designed to obey the refractive index of a half Maxwell fish-eye lens. A planar microstrip Vivaldi antenna is used as transverse magnetic polarized wave launcher for the lens. A prototype of the lens associated with its feed structure has been fabricated using standard lithography techniques. To experimentally demonstrate the broadband focusing properties and directive emissions, both the far-field radiation patterns and the near-field distributions have been measured. Measurements agree quantitatively and qualitatively with theoretical simulations.
Influence of Ga doping on the Cr valence state and ferromagnetism in Cr: ZnO films
Authors: Xiong Ze , Liu Xue-Chao , Zhuo Shi-Yi , Yang Jian-Hua , Shi Er-Wei , Yan Wen-Sheng , Yao Shu-De , Pan Hui-Ping
Published: January 2013

The Zn0.97−xCr0.03GaxO (0 ≤ x ≤ 0.03) films have been prepared by inductively coupled plasma enhanced physical vapor deposition and investigated by soft x-ray absorption spectroscopy. The soft x-ray absorption spectroscopy results indicate Ga doping can substantially transform Cr3+ to Cr2+ and improve the average magnetic moment of Cr ions. The strong localization of carriers suggests the bound magnetic polarons scenario, wherein the reduced localization radius of variable range hopping by the enhancement of high valence state Cr ions can suppress the hopping probability of carriers and stabilize the bound magnetic polarons, leading to a monotonic increase in saturation magnetization.
Orders of magnitude enhancement of optical nonlinearity in subwavelength metal-nonlinear dielectric gratings
Authors: Ironside Daniel J. , Shen Jung-Tsung
Published: January 2013

We show that the optical properties of a metal-nonlinear dielectric grating can be precisely described by a uniform nonlinear dielectric slab. Based upon such a metamaterial mapping, we show that the effective optical nonlinearity in a metal-dielectric grating can be enhanced by orders of magnitude higher than that of the underlying nonlinear dielectric material, is broadband, and can be operated at a low quality-factor regime so as to have an extremely short intrinsic temporal response of a few picoseconds. Furthermore, we demonstrate extraordinary harmonic generation efficiency enhancement and large threshold-power reduction in bistability.
Magnetic and magnetodielectric properties of erbium iron garnet ceramic
Authors: Maignan A. , Singh K. , Simon Ch. , Lebedev O. I. , Martin C. , Tan H. , Verbeeck J. , Van Tendeloo G.
Published: January 2013

An Er3Fe5O12 ceramic has been sintered in oxygen atmosphere at 1400 °C for dielectric measurements. Its structural quality at room temperature has been checked by combining transmission electron microscopy and X-ray diffraction. It crystallizes in the cubic space group Ia3d with a = 12.3488(1). The dielectric permittivity (ε′) and losses (tan δ) measurements as a function of temperature reveal the existence of two anomalies, a broad one between 110 K and 80 K, attributed to the Er3+ spin reorientation, and a second sharper feature at about 45 K associated to the appearance of irreversibility on the magnetic susceptibility curves. In contrast to the lack of magnetic field impact on ε′ for the former anomaly, a complex magnetic field effect has been evidenced below 45 K. The isothermal ε′(H) curves show the existence of positive magnetodielectric effect, reaching a maximum of 0.14% at 3 T and 10 K. Its magnitude decreases as H is further increased. Interestingly, for the lowest H values, a linear regime in the ε′(H) curve is observed. From this experimental study, it is concluded that the ε′ anomaly, starting above the compensation temperature Tc (75 K) and driven by the internal magnetic field, is not sensitive to an applied external magnetic field. Thus, below 45 K, it is the magnetic structure which is responsible for the coupling between spin and charge in this iron garnet.
Silicon surface texturing with a combination of potassium hydroxide and tetra-methyl ammonium hydroxide etching
Authors: Sridharan Sindhuja , Bhat Navakanta , Bhat K. N.
Published: January 2013

A two step silicon surface texturing, consisting of potassium hydroxide (KOH) etching followed by tetra-methyl ammonium hydroxide etching is presented. This combined texturing results in 13.8% reflectivity at 600 nm compared to 16.1% reflectivity for KOH etching due to the modification of microstructure of etched pyramids. This combined etching also results in significantly lower flat-band voltage (VFB) (−0.19 V compared to −1.3 V) and interface trap density (Dit) (2.13 × 1012 cm−2 eV−1 compared to 3.2 × 1012 cm−2 eV−1).
Communication: Solute anisotropy effects in hydrated anion and neutral clusters
Authors: Wen Hui , Hou Gao-Lei , Kathmann Shawn M. , Valiev Marat , Wang Xue-Bin
Published: January 2013

Specific ion effects in solvation processes are often rationalized in terms of spherically symmetric models involving an ion's size, charge, and polarizability. The effects of permanent charge anisotropy, related to the polyatomic nature of complex solutes, are expected to play a role in solvation but the extent of their importance remains unexplored. In this work, we provide compelling experimental and theoretical evidence that the anisotropic nature of complex polyoxyanion solutes can have a critical influence on the solvation process. Combined photoelectron spectroscopy and theoretical modeling results show that the electron binding energy of IO3−(H2O)n (n = 0–12) clusters is characterized by an anomalous drop at n = 10. Such behavior is unprecedented for rigid solute molecules and is related to the anisotropy of the neutral iodate radical that displays a strong selectivity to solvent configurations generated by the charged anion complex. These results highlight the significance of solute anisotropy and its potential impact on ion specificity and selectivity in aqueous environments.
Formation of Si or Ge nanodots in Si3N4 with in-situ donor modulation doping of adjacent barrier material
Authors: König D. , Rudd J.
Published: January 2013

Conventional doping of small nanodots does not provide majority carriers due to self-purification effects and much increased ionisation energies of dopants presenting point defects. Adjacent barrier layers to Si-rich Si3N4 can be doped by excess Si in-situ with the segregation anneal for Si nanodot formation. Donor doping of AlxGa1−xN (0 ⩽ x ⩽ 1) with Si is an established process. Material properties and process compatibility of AlxGa1−xN render it suitable as barrier for Si nanodot superlattices. Ab-initio calculations showed that Ge also works as a donor in AlN, extending the material range to Ge and SiGe nanodots in Si3N4.
Synthesis of silver nanoparticle decorated multiwalled carbon nanotubes-graphene mixture and its heat transfer studies in nanofluid
Authors: Theres Baby Tessy , Sundara Ramaprabhu
Published: January 2013

The present study describes a novel synthesis procedure for a hybrid nanostructure consisting of multiwalled carbon nanotubes (MWNT), hydrogen exfoliated graphene (HEG) and silver nanoparticles. Moreover, synthesis of nanofluids using the above hybrid material and their heat transfer properties are discussed. The hybrid structure of MWNT and HEG (MWNT-HEG) has been synthesized by a simple mixing of MWNT and graphite oxide (GO) followed by exfoliation of this mixture in hydrogen atmosphere. The sample has been characterized with different experimental techniques. After surface functionalization, this hybrid material is decorated with silver nanoparticles (Ag/(MWNT-HEG)) and dispersed in ethylene glycol (EG) without any surfactant. The thermal conductivity and convective heat transfer properties are measured for different volume fractions. An enhancement of ∼8% in thermal conductivity is obtained for a volume fraction of 0.04% at 25°C. The convective heat transfer coefficient of these nanofluids is determined using an in-house fabricated setup. The enhancement in heat transfer coefficient is about 570% for 0.005% volume fraction at the entrance of the pipe for Re = 250.
Designing retrodirective reflector on a planar surface by transformation optics
Authors: Xiong Shuai , Feng Yijun , Jiang Tian , Zhao Junming
Published: January 2013

In this paper, we present the design of a retrodirective reflector with dielectric cover on a planar conducting plane based on the transformation optics. By employing a simple linear coordinate transformation, the retrodirective reflector can be achieved with dielectric cover constructed with homogeneous birefringent dielectric medium, which reduces the complexity of practical realization. Such simple design allows us to further realize the retrodirective reflector by alternative layers of normal dielectrics based on the effective medium theory. The proposed design and a practical realization at microwave regime have been validated by full wave electromagnetic simulation, which demonstrates a broadband retrodirective response range from 5 GHz to 10 GHz.
Alternating current magnetotransport in Sm0.1La0.6Sr0.3MnO3
Authors: Aparnadevi M. , Mahendiran R.
Published: January 2013

We report frequency dependent (f = 0.1 to 5 MHz) electrical resistivity in Sm0.1La0.6Sr0.3MnO3 in superimposed dc magnetic fields (H = 0–1 kOe). Resistive (ρ′) and reactive (ρ″) components of the complex resistivity (ρ = ρ′+iρ″) were measured simultaneously. With increasing f, both ρ′ and ρ′′ increase abruptly at the onset of ferromagnetic transition (Tc = 348 K) and exhibit an anomaly at T *≈ 147 K ≪ Tc in H = 0 kOe. The observed features in ρ′ and ρ′′ are depressed with increasing H leading to 35% magnetoresistance for ΔH = 300 Oe and f = 3 MHz. It is suggested that the frequency dependent magnetotransport is dominated by the field and frequency dependences of the ac permeability.
Lexical-grammatical patterns in spoken English
Authors: Nesselhauf Nadja , Römer Ute
Published: January 2013

Based on a large set of data from one of the biggest available corpora of spoken British English (the 10-million word spoken component of the BNC), this article explores central lexical-grammatical aspects of progressive forms with future time reference. Among the phenomena investigated are verb preferences, adverbial co-selection, subject types, and negation. It is demonstrated that future time progressives in spoken British English are patterned to a considerable extent (for example that it is individual verbs, rather than semantic groups of verbs, that preferably occur in such constructions) and that actual language use often runs counter to claims that can be found in traditional grammatical descriptions of the construction. A number of general and often neglected issues in the analysis of lexical-grammatical patterns are also addressed, in particular the notion of pattern frequency.
A quantitative approach to compare collocational patterns in translated and non‑translated texts
Authors: Dayrell Carmen
Published: January 2013

The primary objective of this paper is to propose a corpus-based research methodology for comparing quantitative aspects of collocational patterning in translated and non-translated texts of the same language. The main issue under investigation is whether collocational patterns tend to be less diverse (i.e. reduced in range) in translated than non-translated texts. A pilot study is carried out with a view to examining the overall number of collocates and the distribution of collocations in relation to a given node in the translated and non-translated subcorpora. The data is drawn from a comparable corpus of Brazilian Portuguese which consists of two separate subcorpora: one made up of translated Brazilian Portuguese and the other consisting of non-translated Brazilian Portuguese. Both subcorpora are designed according to the same criteria and specifications and are of similar size.
Lexical repulsion between sense-related pairs
Authors: Renouf Antoinette , Banerjee Jayeeta
Published: January 2013

This paper builds on the groundwork and setting up of methods for an innovative approach to analysing text. We have proposed that there is a hitherto unexplored textual feature, which we call ‘repulsion’, which operates on the construction of meaning in an opposing way to that of word collocation. To illustrate, we do not say cheerfully happy even though we say blissfully happy. We focus on ‘lexical repulsion’, by which we mean the intuitively-observed tendency in conventional language use for certain pairs of words not to occur together, for no apparent reason other than convention. Our goal is to establish how repulsion as a whole operates and whether it can be assigned the status of an objectively measurable ‘force’. It is anticipated that this approach will have wide implications for corpus linguistics and NLP. In this paper, we take the particular case of repulsion between sense-related word pairs.
Revisiting the Second Russo-Iranian War (1826–28): Causes and Perceptions
Authors: Behrooz Maziar
Published: January 2013

This paper re-examines the causes of outbreak of Second Russo-Iranian War and the factors that played a role in its escalation into fully fledged war. The paper challenges the common perception that Qajar Iran played a major role in the outbreak of the war and proposes that the Qajar court took a defensive posture vis-à-vis aggressive Russian provocation originated in Tiflis and was merely reacting to it. The paper then examines policy differences between Tiflis and the court of St Petersburg as a contributing factor in the outbreak of the war. Finally, the paper examines two different and contradictory views of imperial Russia and its internal politics and military capabilities among Qajar Iran's decision makers during 1825–28. It is argued that the two perceptions eventually translated into two factions, each lobbying the shah for and against escalation of hostilities with Russia.
Counting problems in Apollonian packings
Authors: Fuchs Elena
Published: January 2013

An Apollonian circle packing is a classical construction which is made by repeatedly inscribing circles into the triangular interstices in a Descartes configuration of four mutually tangent circles. Remarkably, if the original four circles have integer curvature, all of the circles in the packing will have integer curvature, making the packings of interest from a number theoretic point of view. Many of the natural arithmetic problems have required new and sophisticated tools to solve them. The reason for this difficulty is that the study of Apollonian packings reduces to the study of a subgroup of

GL

4

(

Z

)

\textrm {GL}_4(\mathbb Z)

that is thin in a sense that we describe in this article, and arithmetic problems involving thin groups have only recently become approachable in broad generality. In this article, we report on what is currently known about Apollonian packings in which all circles have integer curvature and how these results are obtained. This survey is also meant to illustrate how to treat arithmetic problems related to other thin groups.
Effects of reducing inspired oxygen concentration for one hour in patients with chronic heart failure: implications for air travel
Authors: Hobkirk James P. , Damy Thibaud , Walters Mandy , Bennett Anna , Smith Sarah J. , Ingle Lee , Clark Andrew L. , Cleland John G.F.
Published: January 2013

Aims

The objective of this study was to establish the acute effects of hypoxia on clinical, spirometric, haemodynamic, and echocardiographic variables. Reducing inspired oxygen to 15%, as experienced during commercial air travel, decreases arterial oxygen saturation, increases respiratory rate and pulmonary artery pressure in healthy subjects. The effect on patients with chronic heart failure is unknown.

Methods and results

Seventy‐two patients with chronic heart failure and an LVEF <40%, in NYHA functional class II (74%) or III (26%), on stable treatment were studied and compared with 18 age‐matched controls (65 ± 11 vs. 62 ± 12 years, respectively). Clinical, spirometric, haemodynamic, and echocardiographic measurements were performed in patients and controls before and after one hour inspiring 15% oxygen. Inspired 15% oxygen for 1 h was tolerated in all subjects and caused no worsening of symptoms. Arterial oxygen saturation decreased to a similar extent in patients (from 97 ± 2% to 86 ± 4%) and controls (from 97 ± 2% to 86 ± 3%). Mean arterial pressure increased from 81 ± 13 mmHg to 87 ± 12 mmHg in patients, but did not change in controls. There was no effect on heart rate, but systolic pulmonary artery pressure rose from 30.2 ± 14.0mmHg to 34.0 ± 15.2 mmHg in patients, and from 22.4 ± 5.5 mmHg to 24.1 ± 6.9 mmHg in controls.

Conclusions

Inspiring 15% oxygen was tolerated and caused no worsening of symptoms despite reductions in arterial oxygen saturation and increases in mean arterial pressure and systolic pulmonary artery pressure.
Outcomes of Endoscopy and Novel pH‐Impedance Parameters in Children
Authors: van der Pol Rachel J. , Loots Clara M. , Peeters Laura , Vandenplas Yvan , Hauser Bruno , Devreker Thierry , Omari Taher I. , Benninga Marc A. , van Wijk Michiel P.
Published: January 2013

Objectives:

Discordance exists between outcomes of endoscopy, multichannel intraluminal impedance monitoring (pH‐MII), MII baselines, and gastroesophageal reflux symptoms. The aim of the present study was to determine the association between endoscopy, pH‐MII and MII baselines, in children with gastroesophageal reflux symptoms.

Methods:

Endoscopies were graded for reflux esophagitis (RE). Biopsies of the distal esophagus were assessed for signs suggestive of esophagitis. Reflux index (RI), symptom association probability (SAP), number of reflux episodes, and mean baseline values were calculated. pH‐MII was considered positive in children when RI was ≥3% and/or SAP was ≥95% and for infants when RI was ≥10% and/or SAP was ≥95%. Baselines were manually calculated and compared with an automated analysis. For MII baselines, patients were divided in 3 groups: normal endoscopy and negative overall pH‐MII; normal endoscopy and an overall positive pH‐MII; and RE.

Results:

A total of 26 children and 14 infants were included, median age: 26.5 months (2 months–16.2 years). Thirteen (32.5%) had RE. A significant negative association was found for RI and MII baselines (P = 0.009) and between SAP and RE (P = 0.039, odds ratio 1.018). MII baseline values were predictive for neither conventional pH‐MII parameters nor RE. Manual analysis and automated calculation of MII baselines showed a perfect correlation. Distal MII baselines were significantly lower in children with a positive overall pH‐MII outcome compared with the proximal esophagus (P = 0.049). No significant changes were found in baselines among the different groups 1 to 3.

Conclusions:

Acid‐related parameters are significantly related to MII baselines. A perfect correlation between manual‐ and automated analysis of MII baselines was found. Large prospective studies are needed to confirm the exact role of endoscopy and MII baselines.
Conservatism of lizard thermal tolerances and body temperatures across evolutionary history and geography
Authors: Grigg Joseph W. , Buckley Lauren B.
Published: January 2013

Species may exhibit similar thermal tolerances via either common ancestry or environmental filtering and local adaptation, if the species inhabit similar environments. We ask whether upper and lower thermal limits (critical thermal maxima and minima) and body temperatures are more strongly conserved across evolutionary history or geography for lizard populations distributed globally. We find that critical thermal maxima are highly conserved with location accounting for a higher proportion of the variation than phylogeny. Notably, thermal tolerance breadth is conserved across the phylogeny despite critical thermal minima showing little niche conservatism. Body temperatures observed during activity in the field show the greatest degree of conservatism, with phylogeny accounting for most of the variation. This suggests that propensities for thermoregulatory behaviour, which can buffer body temperatures from environmental variation, are similar within lineages. Phylogeny and geography constrain thermal tolerances similarly within continents, but variably within clades. Conservatism of thermal tolerances across lineages suggests that the potential for local adaptation to alleviate the impacts of climate change on lizards may be limited.
Does male reproductive effort increase with age? Courtship in fiddler crabs
Authors: Hayes Catherine L. , Booksmythe Isobel , Jennions Michael D. , Backwell Patricia R. Y.
Published: January 2013

Theory suggests that reproductive effort generally increases with age, but life-history models indicate that other outcomes are possible. Empirical data are needed to quantify variation in actual age-dependence. Data are readily attainable for females (e.g. clutch per egg size), but not for males (e.g. courtship effort). To quantify male effort one must: (i) experimentally control for potential age-dependent changes in female presence; and, crucially, (ii) distinguish between the likelihood of courtship being initiated, the display rate, and the total time invested in courting before stopping (‘courtship persistence’). We provide a simple experimental protocol, suitable for many taxa, to illustrate how to obtain this information. We studied courtship waving by male fiddler crabs,
Uca annulipes
. Given indeterminate growth, body size is correlated with age. Larger males were more likely to wave at females and waved more persistently. They did not, however, have a higher courtship rate (waves per second). A known female preference for males with higher display rates explains why, once waving is initiated, all males display at the same rate.
Sticking like sticky tape: tree frogs use friction forces to enhance attachment on overhanging surfaces
Authors: Endlein Thomas , Ji Aihong , Samuel Diana , Yao Ning , Wang Zhongyuan , Barnes W. Jon P. , Federle Walter , Kappl Michael , Dai Zhendong
Published: January 2013

To live and clamber about in an arboreal habitat, tree frogs have evolved adhesive pads on their toes. In addition, they often have long and slender legs to facilitate not only long jumps, but also to bridge gaps between leaves when climbing. Both adhesive pads and long limbs are used in conjunction, as we will show in this study. Previous research has shown that tree frogs change from a crouched posture (where the limbs are close to the body) to a sprawled posture with extended limbs when clinging on to steeper inclines such as vertical or overhanging slopes. We investigated this change in posture in White's tree frogs (Litoria caerulea) by challenging the frogs to cling onto a tiltable platform. The platform consisted of an array of 24 three-dimensional force transducers, which allowed us to measure the ground reaction forces of the frogs during a tilt. Starting from a crouched resting position, the normal forces on the forelimbs changed sign and became increasingly negative with increasing slope angle of the platform. At about 106°±12°, tilt of the platform the frogs reacted by extending one or two of their limbs outwards. At a steeper angle (131°±11°), the frogs spread out all their limbs sideways, with the hindlimbs stretched out to their maximum reach. Although the extension was strongest in the lateral direction, limbs were significantly extended in the fore–aft direction as well. With the extension of the limbs, the lateral forces increased relative to the normal forces. The large contribution of the in-plane forces helped to keep the angle between the force vector and the platform small. The Kendall theory for the peeling of adhesive tape predicts that smaller peel angles lead to higher attachment forces. We compare our data with the predictions of the Kendall model and discuss possible implications of the sliding of the pads on the surface. The forces were indeed much larger for smaller angles and thus can be explained by peeling theory.
Spatial stochastic modelling of the Hes1 gene regulatory network: intrinsic noise can explain heterogeneity in embryonic stem cell differentiation
Authors: Sturrock Marc , Hellander Andreas , Matzavinos Anastasios , Chaplain Mark A. J.
Published: January 2013

Individual mouse embryonic stem cells have been found to exhibit highly variable differentiation responses under the same environmental conditions. The noisy cyclic expression of Hes1 and its downstream genes are known to be responsible for this, but the mechanism underlying this variability in expression is not well understood. In this paper, we show that the observed experimental data and diverse differentiation responses can be explained by a spatial stochastic model of the Hes1 gene regulatory network. We also propose experiments to control the precise differentiation response using drug treatment.
How do variations in seasonality affect population cycles?
Authors: Taylor Rachel A. , White Andrew , Sherratt Jonathan A.
Published: January 2013

Seasonality is an important component in many population systems, and factors such as latitude, altitude and proximity to the coastline affect the extent of the seasonal fluctuations. In this paper, we ask how changes in seasonal fluctuations impact on the population cycles. We use the Fennoscandian vole system as a case study, focusing on variations in the length of the breeding season. We use a predator–prey model that includes generalist and specialist predation alongside seasonal forcing. Using a combination of bifurcation analysis and direct simulations, we consider the effects of varying both the level of generalist predation and the length of the breeding season; these are the main changes that occur over a latitudinal gradient in Fennoscandia. We predict that varying the breeding season length leads to changes in the period of the multi-year cycles, with a higher period for shorter breeding season lengths. This concurs with the gradient of periodicity found in Fennoscandia. The Fennoscandian vole system is only one of many populations that are affected by geographical and temporal changes in seasonality; thus our results highlight the importance of considering these changes in other population systems.
Extreme climatic event drives range contraction of a habitat-forming species
Authors: Smale Dan A. , Wernberg Thomas
Published: January 2013

Species distributions have shifted in response to global warming in all major ecosystems on the Earth. Despite cogent evidence for these changes, the underlying mechanisms are poorly understood and currently imply gradual shifts. Yet there is an increasing appreciation of the role of discrete events in driving ecological change. We show how a marine heat wave (HW) eliminated a prominent habitat-forming seaweed,
Scytothalia dorycarpa
, at its warm distribution limit, causing a range contraction of approximately 100 km (approx. 5% of its global distribution). Seawater temperatures during the HW exceeded the seaweed's physiological threshold and caused extirpation of marginal populations, which are unlikely to recover owing to life-history traits and oceanographic processes.
Scytothalia dorycarpa
is an important canopy-forming seaweed in temperate Australia, and loss of the species at its range edge has caused structural changes at the community level and is likely to have ecosystem-level implications. We show that extreme warming events, which are increasing in magnitude and frequency, can force step-wise changes in species distributions in marine ecosystems. As such, return times of these events have major implications for projections of species distributions and ecosystem structure, which have typically been based on gradual warming trends.
FGF7 is a functional niche signal required for stimulation of adult liver progenitor cells that support liver regeneration
Authors: Takase Hinako M. , Itoh Tohru , Ino Seitaro , Wang Ting , Koji Takehiko , Akira Shizuo , Takikawa Yasuhiro , Miyajima Atsushi
Published: January 2013

The liver is a unique organ with a remarkably high potential to regenerate upon injuries. In severely damaged livers where hepatocyte proliferation is impaired, facultative liver progenitor cells (LPCs) proliferate and are assumed to contribute to regeneration. An expansion of LPCs is often observed in patients with various types of liver diseases. However, the underlying mechanism of LPC activation still remains largely unknown. Here we show that a member of the fibroblast growth factor (FGF) family, FGF7, is a critical regulator of LPCs. Its expression was induced concomitantly with LPC response in the liver of mouse models as well as in the serum of patients with acute liver failure. Fgf7-deficient mice exhibited markedly depressed LPC expansion and higher mortality upon toxin-induced hepatic injury. Transgenic expression of FGF7 in vivo led to the induction of cells with characteristics of LPCs and ameliorated hepatic dysfunction. We revealed that Thy1+ mesenchymal cells produced FGF7 and appeared in close proximity to LPCs, implicating a role for those cells as the functional LPC niche in the regenerating liver. These findings provide new insights into the cellular and molecular basis for LPC regulation and identify FGF7 as a potential therapeutic target for liver diseases.
Perirhinal and postrhinal, but not lateral entorhinal, cortices are essential for acquisition of trace eyeblink conditioning
Authors: Suter Eugénie E. , Weiss Craig , Disterhoft John F.
Published: January 2013

The acquisition of temporal associative tasks such as trace eyeblink conditioning is hippocampus-dependent, while consolidated performance is not. The parahippocampal region mediates much of the input and output of the hippocampus, and perirhinal (PER) and entorhinal (EC) cortices support persistent spiking, a possible mediator of temporal bridging between stimuli. Here we show that lesions of the perirhinal or postrhinal cortex severely impair the acquisition of trace eyeblink conditioning, while lateral EC lesions do not. Our findings suggest that direct projections from the PER to the hippocampus are functionally important in trace acquisition, and support a role for PER persistent spiking in time-bridging associations.
Genetic, Hormonal, and Physiological Analysis of Late Maturity α-Amylase in Wheat
Authors: Barrero Jose M. , Mrva Kolumbina , Talbot Mark J. , White Rosemary G. , Taylor Jennifer , Gubler Frank , Mares Daryl J.
Published: January 2013

Late maturity α-amylase (LMA) is a genetic defect that is commonly found in bread wheat (Triticum aestivum) cultivars and can result in commercially unacceptably high levels of α-amylase in harvest-ripe grain in the absence of rain or preharvest sprouting. This defect represents a serious problem for wheat farmers, and apart from the circumstantial evidence that gibberellins are somehow involved in the expression of LMA, the mechanisms or genes underlying LMA are unknown. In this work, we use a doubled haploid population segregating for constitutive LMA to physiologically analyze the appearance of LMA during grain development and to profile the transcriptomic and hormonal changes associated with this phenomenon. Our results show that LMA is a consequence of a very narrow and transitory peak of expression of genes encoding high-isoelectric point α-amylase during grain development and that the LMA phenotype seems to be a partial or incomplete gibberellin response emerging from a strongly altered hormonal environment.
The ArabidopsisTUMOR PRONE5Gene Encodes an Acetylornithine Aminotransferase Required for Arginine Biosynthesis and Root Meristem Maintenance in Blue Light
Authors: Frémont Nathalie , Riefler Michael , Stolz Andrea , Schmülling Thomas
Published: January 2013

Arginine is an essential amino acid necessary for protein synthesis and is also a nitrogen storage compound. The genes encoding the enzymes of arginine biosynthesis in plants are not well characterized and have mainly been predicted from homologies to bacterial and fungal genes. We report the cloning and characterization of the TUMOR PRONE5 (TUP5) gene of Arabidopsis (Arabidopsis thaliana) encoding an acetylornithine aminotransferase (ACOAT), catalyzing the fourth step of arginine biosynthesis. The free arginine content was strongly reduced in the chemically induced recessive mutant tup5-1, root growth was restored by supplementation with arginine and its metabolic precursors, and a yeast (Saccharomyces cerevisiae) ACOAT mutant was complemented by TUP5. Two null alleles of TUP5 caused a reduced viability of gametes and embryo lethality, possibly caused by insufficient Arg supply from maternal tissue. TUP5 expression is positively regulated by light, and a TUP5-green fluorescent protein was localized in chloroplasts. tup5-1 has a unique light-dependent short root phenotype. Roots of light-grown tup5-1 seedlings switch from indeterminate growth to determinate growth with arresting cell production and an exhausted root apical meristem. The inhibitory activity was specific for blue light, and the inhibiting light was perceived by the root. Thus, tup5-1 reveals a novel role of amino acids and blue light in regulating root meristem function.
SrRietveld: a program for automating Rietveld refinements for high-throughput powder diffraction studies
Authors: Tian P. , Zhou W. , Liu J. , Shang Y. , Farrow C. L. , Juhás P. , Billinge S. J. L.
Published: January 2013

SrRietveldis a highly automated software toolkit for Rietveld refinement. Compared to traditional refinement programs, it is more efficient to use and easier to learn. It is designed for modern high-throughput diffractometers and is capable of processing large numbers of data sets with minimal effort. The software currently uses conventional Rietveld refinement engines, automatingGSASandFullProfrefinements. However, as well as automating and extending many tasks associated with these programs, it is designed in a flexible and extensible way so that in the future these engines can be replaced with new refinement engines as they become available.SrRietveldis an open-source software package developed in Python.
Resonant X-ray scattering studies of epitaxial complex oxide thin films
Authors: Perret Edith , Park Changyong , Fong Dillon D. , Chang Kee-Chul , Ingram Brian J. , Eastman Jeffrey A. , Baldo Peter M. , Fuoss Paul H.
Published: January 2013

Resonant anomalous X-ray reflectivity (RAXR) is a powerful technique for measuring element-specific distribution profiles across surfaces and buried interfaces. Here, the RAXR technique is applied to characterize a complex oxide heterostructure, La0.6Sr0.4Co0.2Fe0.8O3−δ, on NdGaO3, and the effects of data sampling and model-dependent fitting procedures on the extracted elemental distribution profile are evaluated. The strontium profile through a 3.5 nm-thick film at 973 K and at an oxygen partial pressure of 150 Torr (1 Torr = 133.32 Pa) was determined from the measured RAXR spectra. The results demonstrate thatin situRAXR measurements can provide key insights into temperature- and environment-dependent elemental segregation processes, relevant, for example, in assessing the cathode performance of solid oxide fuel cells.
Short-range and long-range order of phyllomanganate nanoparticles determined using high-energy X-ray scattering
Authors: Manceau Alain , Marcus Matthew A. , Grangeon S. , Lanson M. , Lanson B. , Gaillot A.-C. , Skanthakumar S. , Soderholm L.
Published: January 2013

High-energy X-ray scattering (HEXS) is used to explore the pH-dependent structure of randomly stacked manganese oxide nanosheets of nominal formula δ-MnO2. Data are simulated in real space by pair distribution function (PDF) analysis and in reciprocal space by both the Bragg-rod method and the Debye equation in order to maximize the information gained from the total scattering measurements. The essential new features of this triple-analysis approach are (1) the use of a two-dimensional supercell in PDF modeling to describe local distortions around Mn layer vacancies, (2) the implementation in Bragg-rod calculations of a lognormal crystal size distribution in the layer plane and an empirical function for the effect of strain, and (3) the incorporation into the model used with the Debye equation of an explicit elastic deformation of the two-dimensional nanocrystals. The PDF analysis reveals steady migration at acidic pH of the Mn atoms from layer to interlayer sites, either above or below the Mn layer vacancies, and important displacement of the remaining in-layer Mn atoms toward vacancies. The increased density of the vacancy–interlayer Mn pairs at low pH causes their mutual repulsion and results in short-range ordering. The layer microstructure, responsible for the long-range lateral disorder, is modeled with spherically and cylindrically bent crystallites having volume-averaged radii of 20–40 Å. Thebunit-cell parameter from the hexagonal layer has different values in PDF, Bragg-rod and Debye equation modeling, because of the use of different weighting contributions from long-range and short-range distances in each method. The PDFbparameter is in effect a measure of the average inlayer Mn...Mn distance and consistently deviates from the average structure value determined by the Bragg-rod method by 0.02 Å at low pH, as a result of the local relaxation induced by vacancies. The layer curvature increases the Bragg-rod value by 0.01–0.02 Å with the cylindrical model and as much as 0.04–0.05 Å with the spherical model. Therefore, in principle, the diffraction alone can unambiguously determine with good accuracy only a volume-averaged apparent layer dimension of the manganese oxide nanosheets. Thebparameter is model dependent and has no single straightforward interpretation, so comparison ofbbetween different samples only makes sense if done in the context of a single specified model.
Thermal equilibration of samples for neutron scattering
Authors: Herman Tobias K. , Parks Sarah C. , Scherschligt Julia
Published: January 2013

Temperature relaxation and equilibration of samples for neutron scattering was investigated in a selection of samples and sample cells within the range of 5–300 K. A simple model was developed that relates thermal relaxation time constants to material properties of the sample and sample cell. This model should facilitate extension of this study to prediction of thermal behavior in other systems.
ABSORB-7andABSORB-GUIfor single-crystal absorption corrections
Authors: Angel Ross , Gonzalez-Platas Javier
Published: January 2013

ABSORBis a program to calculate and apply absorption corrections to single-crystal X-ray intensity data from any source, any detector type and any instrument configuration. A new version,ABSORB-7, contains several significant new features.ABSORB-GUIhas been developed to allow much easier specification of standard experiments and to enable experimental information to be imported from diffractometer software. The program that calculates the absorption calculations has been reconfigured to allow it to be called directly from other commercial and non-commercial software packages. In addition, a number of new features have been introduced to allow more flexibility in the way the experimental configuration is described and to correct synchrotron diffraction data collected with beams smaller than the sample crystal.
Improvement of crystal quality for tetragonal hen egg white lysozyme crystals under application of an external alternating current electric field
Authors: Koizumi H. , Uda S. , Fujiwara K. , Tachibana M. , Kojima K. , Nozawa J.
Published: January 2013

X-ray diffraction rocking-curve measurements were performed on tetragonal hen egg white lysozyme (HEWL) crystals grown with and without application of an external alternating current (AC) electric field, and then the crystal quality was assessed by the FWHMs of each rocking-curve profile. The FWHMs for HEWL crystals grown with an external electric field were smaller than those for crystals grown without. In particular, the average FWHM for the 12 12 0 reflection with an external electric field (0.0034°) was significantly smaller than that without (0.0061°). This indicates that the crystal quality of HEWL crystals was improved by application of the external AC electric field. This crystallization technique can be expected to enhance the resolution of protein molecule structure analysis by X-ray diffraction.
On the determination of the helical structure parameters of amyloid protofilaments by small-angle neutron scattering and atomic force microscopy
Authors: Avdeev Mikhail V. , Aksenov Victor L. , Gazová Zuzana , Almásy László , Petrenko Viktor I. , Gojzewski Hubert , Feoktystov Artem V. , Siposova Katarina , Antosova Andrea , Timko Milan , Kopcansky Peter
Published: January 2013

The helical structure of amyloid protofilaments of hen egg white lysozyme was analyzed by small-angle neutron scattering (SANS) and atomic force microscopy (AFM). The structure of these formations in bulk solutions was adequately described by SANS in terms of a simplified model of a helix with spherical structural units. The found main helix parameters (pitch and effective diameter) are consistent with the results of AFM analysis for amyloid fibrils adsorbed on a mica surface. Both methods reveal a strong isotope effect on the structure of amyloid fibrils with respect to the substitution of heavy for light water in the solvent. Specific details responsible for the structural differences when comparing SANS and AFM data are discussed from the viewpoint of methodological aspects, the influence of different (native and adsorbed) amyloid states and sample preparation.
Scherrer grain-size analysis adapted to grazing-incidence scattering with area detectors. Erratum
Authors: Smilgies Detlef-M.
Published: January 2013

A poor divergence value in the paper by Smilgies [J. Appl. Cryst.(2009),42, 1030–1034] is corrected.
Adverse events following statin–fenofibrate therapy versus statin alone: A meta‐analysis of randomized controlled trials
Authors: Geng Qiang , Ren Jingyi , Chen Hong , Lee Chongyou , Liang Wenqing
Published: January 2013

The combination of fenofibrate with statins is a beneficial therapeutic option for patients with mixed dyslipidaemia, but concerns about adverse events (AEs) make physicians reluctant to use this combination therapy.

Medline, Embase and the Cochrane Library were searched to identify 13 randomized controlled trials, involving 7712 patients, of statin–fenofibrate therapy versus statin alone for review.

There were significant decreases in low‐density lipoprotein–cholesterol, triglycerides and total cholesterol and increases in high‐density lipoprotein–cholesterol in patients receiving combination therapy compared with statin therapy alone. The incidence of aminotransferase elevations in the fenofibrate–statin therapy group was significantly higher than in the statin monotherapy group (odds ratio (OR), 1.66; 95% confidence interval (CI) 1.17–2.37; P < 0.05). The incidence of elevated creatine kinase levels (OR 0.88; 95% CI 0.63–1.23; P > 0.05), muscle‐associated AEs (OR 0.98; 95% CI 0.88–1.09; P > 0.05) and withdrawals attributed to liver and muscle dysfunction did not differ significantly between the two groups. The efficacy of fenofibrate + standard‐dose statin and incidence of AEs in the fenofibrate + standard‐dose statin group were almost identical to those in the fenofibrate–statin group.

In conclusion, combination therapy improves the blood lipid profile of patients. Fenofibrate–statin combination therapy appears to be as well tolerated as statin monotherapy. Physicians should consider fenofibrate–statin combination therapy in patients but monitor aminotransferase levels to avoid hepatic complications.
Jaundice and life‐threatening hemobilia: An uncommon presentation of choledochal cyst
Authors: Koh Peng Soon , Yoong Boon Koon , Vijayananthan Anushya , Nawawi Ouzreiah , Mahadeva Sanjiv
Published: January 2013

Hemobilia with jaundice as a result of cholestasis and bleeding from choledochal cyst is uncommon. Ascertaining the diagnosis is often challenging and delayed diagnosis can lead to significant consequences due to hemodynamic instability, particularly in elderly patients. Although surgery remains the definitive treatment modality, interventional radiology for hemostasis has been increasingly recognized as an option. In this manuscript, we described two Malaysian cases of jaundice and hemobilia associated with choledochal cysts and the challenges related with clinical diagnosis and management.
Cognitive endophenotypes in a family with bipolar disorder with a risk locus on chromosome 4
Authors: Drysdale Emma , Knight Helen M , McIntosh Andrew M , Blackwood Douglas HR
Published: January 2013

Objectives:  We studied cognitive function in high‐risk relatives belonging to a single extended family showing linkage of bipolar disorder to a locus on chromosome 4. High‐risk relatives were defined as those that carried the risk haplotype of polymorphic markers, identified in a previous linkage study. This family provided a rare opportunity to characterize a neuropsychological endophenotype in a homogeneous sample of relatives with a common genetic risk factor.

Methods:  Fifteen family members carrying the risk haplotype (eight diagnosed with bipolar disorder or depression and seven with no psychiatric diagnosis), unrelated patients with bipolar disorder (n = 36) and major depressive disorder (n = 40), and healthy control subjects (n = 33) were administered the California Verbal Learning Test, Verbal Fluency Test, Hayling Sentence Completion Test, and Brixton Spatial Anticipation Test to assess verbal memory, verbal fluency, and executive function.

Results:  Compared with healthy controls, family members carrying the risk haplotype were impaired in indices of memory and executive function. There were no significant differences between unaffected and affected haplotype‐carrying family members in any cognitive measure. Pronounced deficits in the encoding stage of verbal memory and category verbal fluency were evident in individuals with the risk haplotype.

Conclusions:  Verbal learning and semantic verbal fluency impairments may represent a cognitive endophenotype for both bipolar disorder and major depression in relatives of bipolar disorder patients, as impairment was also present in high‐risk relatives who had not developed any affective disorder symptoms. These findings suggest that impairment in semantic organization may be linked to the genetic aetiology of bipolar disorder.