bluuebunny/crossref_metadata_2025 huggingface dataset:
Diffusion of degenerate minority carriers in a p-type semiconductor
Authors: Weber C. P. , Kittlaus Eric A.
Published: February 2013

We report ultrafast transient-grating experiments on heavily p-type InP at 15 K. Our measurement reveals the dynamics and diffusion of photoexcited electrons and holes as a function of their density n in the range 2  ×  1016 to 6  ×  1017 cm−3. After the first few picoseconds, the grating decays primarily due to ambipolar diffusion. While, at low density, we observe a regime in which the ambipolar diffusion is electron-dominated and increases rapidly with n, it appears to saturate at 34 cm2/s at high n. We present a simple calculation that reproduces the main results of our measurements as well as of previously published measurements that had shown diffusion to be a flat or decreasing function of n. By accounting for effect of density on charge susceptibility, we show that, in p-type semiconductors, the regime we observe of increasing ambipolar diffusion is unique to heavy doping and low temperature, where both the holes and electrons are degenerate; in this regime, the electronic and ambipolar diffusion are nearly equal. The saturation is identified as a crossover to ambipolar diffusion dominated by the majority carriers, the holes. At short times, the transient-grating signal rises gradually. This rise reveals cooling of hot electrons and, at high photocarrier density, allows us to measure ambipolar diffusion of 110 cm2/s in the hot-carrier regime.
Insertion of lithium ions into TiO2 (rutile) crystals: An electron paramagnetic resonance study of the Li-associated Ti3+ small polaron
Authors: Brant A. T. , Giles N. C. , Halliburton L. E.
Published: February 2013

Electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) are used to identify a Ti3+-Li+ complex in TiO2 crystals having the rutile structure. This defect consists of an interstitial Li+ ion adjacent to a substitutional Ti3+ ion (the unpaired electron on the Ti3+ ion provides charge compensation for the Li+ ion). The neutral Ti3+-Li+ complex is best described as a donor-bound small polaron and is similar in structure to the recently reported neutral fluorine and hydrogen donors in TiO2 (rutile). Lithium ions are diffused into the crystals at temperatures near 450 °C. Following the diffusion, an EPR spectrum containing groups of four closely spaced lines is observed at 36 K without laser illumination. ENDOR data verify that the four lines within each group are due to a weak hyperfine interaction with one lithium nucleus. Spin-Hamiltonian parameters are obtained from the angular dependence of the EPR spectra. Principal values are 1.9688, 1.9204, and 1.9323 for the g matrix and –2.14, –2.20, and +3.44 MHz for the 7Li hyperfine matrix.
Electronic screening in stacked graphene flakes revealed by scanning tunneling microscopy
Authors: Feng Xiaofeng , Salmeron Miquel
Published: February 2013

Electronic doping and screening effects in stacked graphene flakes on Ru and Cu substrates have been observed using scanning tunneling microscopy (STM). The screening affects the apparent STM height of each flake in successive layers reflecting the density of states near the Fermi level and thus the doping level. It is revealed in this way that the strong doping of the first graphene layer on Ru(0001) is attenuated in the second one, and almost eliminated in the third and fourth layers. Similar effect is also observed in graphene flakes on Cu(111). In contrast, the strong doping effect is suppressed immediately by a water layer intercalated between the graphene and Ru.
Electrical transport properties of boron-doped single-walled carbon nanotubes
Authors: Li Y. F. , Wang Y. , Chen S. M. , Wang H. F. , Kaneko T. , Hatakeyama R.
Published: February 2013

The transport properties of B-doped single-walled carbon nanotubes (SWNTs) are studied from both experimental and theoretical standpoints. Experimentally, it is found that the semiconducting behavior of SWNTs is drastically changed after B-doping, and the unusual abrupt current drops are observed at low temperatures, which may imply the possibility of superconducting transition in B-doped SWNTs. Using the density-functional tight-binding calculation, it is observed that B-doping induces the presence of density of state peaks near the Fermi level which shifts toward the valence band region, showing a clear charge-transfer characteristic, which agrees well with the experimental observations.
Nanoparticles charge response from electrostatic force microscopy
Authors: Mottaghizadeh A. , Lang P. L. , Cui L. M. , Lesueur J. , Li J. , Zheng D. N. , Rebuttini V. , Pinna N. , Zimmers A. , Aubin H.
Published: February 2013

Electrostatic force microscopy (EFM) allows measurement of tiny changes in tip-sample capacitance. When nanoobjects are studied by EFM, they only contribute a very small fraction of the total capacitance between the tip and the sample. We show that the analysis of 3D maps of the EFM signal allows extracting the contribution of the nanomaterial to the total capacitance. This opens the way to applications of EFM as a measure of the dielectric coefficient of electrically insulating nanomaterials or the quantum capacitance of conducting nanomaterials. We apply this method to study the charge response of magnetite, Fe3O4, nanoparticles.
Shell-thickness-dependent photoinduced electron transfer from CuInS2/ZnS quantum dots to TiO2 films
Authors: Sun Jianhui , Zhao Jialong , Masumoto Yasuaki
Published: February 2013

We demonstrate the electron transfer (ET) processes from CuInS2/ZnS core/shell quantum dots (QDs) into porous anatase TiO2 films by time-resolved photoluminescence spectroscopy. The rate and efficiency of ET can be controlled by changing the core diameter and the shell thickness. It is found that the ET rates decrease exponentially at the decay constants of 1.1 and 1.4 nm–1 with increasing ZnS shell thickness for core diameters of 2.5 and 4.0 nm, respectively, in agreement with the electron tunneling model. This shows that optimized ET efficiency and QD stability can be realized by controlling the shell thickness.
Thermal analysis of amorphous oxide thin-film transistor degraded by combination of joule heating and hot carrier effect
Authors: Urakawa Satoshi , Tomai Shigekazu , Ueoka Yoshihiro , Yamazaki Haruka , Kasami Masashi , Yano Koki , Wang Dapeng , Furuta Mamoru , Horita Masahiro , Ishikawa Yasuaki , Uraoka Yukiharu
Published: February 2013

Stability is the most crucial issue in the fabrication of oxide thin-film transistors (TFTs) for next-generation displays. We have investigated the thermal distribution of an InSnZnO TFT under various gate and drain voltages by using an infrared imaging system. An asymmetrical thermal distribution was observed at a local drain region in a TFT depending on bias stress. These phenomena were decelerated or accelerated with stress time. We discussed the degradation mechanism by analyzing the electrical properties and thermal distribution. We concluded that the degradation phenomena are caused by a combination of Joule heating and the hot carrier effect.
Current crowding effects in superconducting corner-shaped Al microstrips
Authors: Adami O.-A. , Cerbu D. , Cabosart D. , Motta M. , Cuppens J. , Ortiz W. A. , Moshchalkov V. V. , Hackens B. , Delamare R. , Van de Vondel J. , Silhanek A. V.
Published: February 2013

The superconducting critical current of corner-shaped Al superconducting microstrips has been investigated. We demonstrate that the sharp turns lead to asymmetric vortex dynamics, allowing for easier penetration from the inner concave angle than from the outer convex angle. This effect is evidenced by a rectification of the voltage signal otherwise absent in straight superconducting strips. At low magnetic fields, an enhancement of the critical current with increasing magnetic field is observed for a particular combination of field and current polarity, confirming a theoretically predicted competing interplay of superconducting screening currents and applied currents at the inner side of the turn.
Nonlinear bleaching, absorption, and scattering of 532-nm-irradiated plasmonic nanoparticles
Authors: Liberman V. , Sworin M. , Kingsborough R. P. , Geurtsen G. P. , Rothschild M.
Published: February 2013

Single-pulse irradiation of Au and Ag suspensions of nanospheres and nanodisks with 532-nm 4-ns pulses has identified complex optical nonlinearities while minimizing material damage. For all materials tested, we observe competition between saturable absorption (SA) and reverse SA (RSA), with RSA behavior dominating for intensities above ∼50 MW/cm2. Due to reduced laser damage in single-pulse experiments, the observed intrinsic nonlinear absorption coefficients are the highest reported to date for Au nanoparticles. We find size dependence to the nonlinear absorption enhancement for Au nanoparticles, peaking in magnitude for 80-nm nanospheres and falling off at larger sizes. The nonlinear absorption coefficients for Au and Ag spheres are comparable in magnitude. On the other hand, the nonlinear absorption for Ag disks, when corrected for volume fraction, is several times higher. These trends in nonlinear absorption are correlated to local electric field enhancement through quasi-static mean-field theory. Through variable size aperture measurements, we also separate nonlinear scattering from nonlinear absorption. For all materials tested, we find that nonlinear scattering is highly directional and that its magnitude is comparable to that of nonlinear absorption. These results indicate methods to improve the efficacy of plasmonic nanoparticles as optical limiters in pulsed laser systems.
Paper pump for passive and programmable transport
Authors: Wang Xiao , Hagen Joshua A. , Papautsky Ian
Published: February 2013

In microfluidic systems, a pump for fluid-driving is often necessary. To keep the size of microfluidic systems small, a pump that is small in size, light-weight and needs no external power source is advantageous. In this work, we present a passive, simple, ultra-low-cost, and easily controlled pumping method based on capillary action of paper that pumps fluid through conventional polymer-based microfluidic channels with steady flow rate. By using inexpensive cutting tools, paper can be shaped and placed at the outlet port of a conventional microfluidic channel, providing a wide range of pumping rates. A theoretical model was developed to describe the pumping mechanism and aid in the design of paper pumps. As we show, paper pumps can provide steady flow rates from 0.3 μl/s to 1.7 μl/s and can be cascaded to achieve programmable flow-rate tuning during the pumping process. We also successfully demonstrate transport of the most common biofluids (urine, serum, and blood). With these capabilities, the paper pump has the potential to become a powerful fluid-driving approach that will benefit the fielding of microfluidic systems for point-of-care applications.
Design and numerical optimization of an easy-to-fabricate photon-to-plasmon coupler for quantum plasmonics
Authors: Kewes Günter , Schell Andreas W. , Henze Rico , Simon Schönfeld Rolf , Burger Sven , Busch Kurt , Benson Oliver
Published: February 2013

We design an on-chip single mode photon to surface-plasmon coupler. Our coupler consists of a tapered dielectric waveguide and a V-shaped plasmonic part. In contrast to other concepts designated to minimized-loss coupling into long-ranging waveguides, we focus on an easy-to-fabricate structure working in the visible spectral range. The air-cladded design provides full experimental access to the evanescent fields emerging from the plasmonic stripe guide. An adaptive finite element method for full three dimensional simulations is used combined with the Taguchi method for optimization, which makes our procedure extremely time-efficient and executable on standard personal computers.
Portable optical-resolution photoacoustic microscopy with a pulsed laser diode excitation
Authors: Zeng Lvming , Liu Guodong , Yang Diwu , Ji Xuanrong
Published: February 2013

Optical-resolution photoacoustic microscopy (OR-PAM) has been significantly improved in terms of spatial resolution, detection sensitivity, imaging speed, and penetration depth. However, the popular producibility of OR-PAM system is still limited by the size and cost of solid-state laser excitation. Here, we developed a portable laser-diode-based OR-PAM (LD-OR-PAM) system using a pulsed semiconductor laser source, which was operated at 905 ± 15 nm with a pulse energy as low as 4.9 μJ. The measured lateral resolution has been improved to ∼1.5 μm from hundreds of microns. The compact and inexpensive natures of LD-OR-PAM would promote the potential clinical applications such as in dermatology.
Ultra-thin Co/Pd multilayers with enhanced high-temperature annealing stability
Authors: Gottwald M. , Lee K. , Kan J. J. , Ocker B. , Wrona J. , Tibus S. , Langer J. , Kang S. H. , Fullerton E. E.
Published: February 2013

Understanding the thermal budget of perpendicular materials is crucial for the potential application perpendicular magnetic tunnel junctions. In this paper, we study the effects of high-temperature rapid thermal annealing on the structural and magnetic properties of ultra-thin Co/Pd multilayers deposited at room temperature. It is shown that perpendicular magnetic anisotropy of ultra-thin Co/Pd multilayers improves with increasing annealing temperature up to 425 °C. This property of ultra-thin Co/Pd multilayers provides increased thermal budgets for CMOS-integrated magnetic devices.
Enhanced InAs nanopillar electrical transport by in-situ passivation
Authors: Lin A. , Shapiro J. N. , Scofield A. C. , Liang B. L. , Huffaker D. L.
Published: February 2013

We investigate the effects of in-situ passivation on the electrical transport of InAs nanopillars (NPs) grown on InAs (111)B substrates via selective-area epitaxy. Before passivation, the transport properties of InAs NPs, studied by single-NP field-effect transistors, are highly dependent on NP dimensions. With diameters ranging from 70 nm to 200 nm, we find significant differences in resistivity and extracted field-effect mobility (μeff). Growing a 6 nm InP shell for in-situ passivation significantly enhances these transport properties of InAs channel with diameter-independent μeff as high as 6900 cm2/V s. Such heterostructures have the potential as future high electron mobility transistors.
Origin of the colossal dielectric properties in double-perovskite Sr2CoNbO6
Authors: Wang G. J. , Wang C. C. , Huang S. G. , Sun X. H. , Lei C. M. , Li T. , Liu L. N.
Published: February 2013

Sr2CoNbO6 ceramics were prepared via the solid-state reaction route. The dielectric properties of Sr2CoNbO6 ceramics were investigated as a function of temperature (90–330 K) in the frequency range from 20 Hz to 10 MHz. Our results reveal that the dielectric properties of Sr2CoNbO6 are closely linked with the conductivity of the sample. The conductivity is dominated by hopping localized carriers. The hopping process not only produces considerable conductivity followed the universal dielectric response behavior, but also gives rise to dipolar effects leading to the polaron relaxation in intermediate-temperature range. At low enough temperatures, the hopping process is frozen-in and the low-temperature Maxwell-Wagner relaxation due to frozen carriers featuring the nearly constant loss behavior appears. At higher temperatures, the long-distance transportation of the carriers becomes remarkable. These carriers are easily blocked by various interfaces resulting in space charge therein and the conventional Maxwell-Wagner relaxation in the high-temperature range. Our results demonstrate that a multirelaxation mechanism instead of a single relaxation underlies the colossal dielectric properties of Sr2CoNbO6.
Understanding Urban Traffic-Flow Characteristics: A Rethinking of Betweenness Centrality
Authors: Gao Song , Wang Yaoli , Gao Yong , Liu Yu
Published: February 2013

In this study we estimate urban traffic flow using GPS-enabled taxi trajectory data in Qingdao, China, and examine the capability of the betweenness centrality of the street network to predict traffic flow. The results show that betweenness centrality is not a good predictor variable for urban traffic flow, which has, theoretically, been pointed out in existing literature. With a critique of the betweenness centrality as a predictor, we further analyze the characteristics of betweenness centrality and point out the ‘gap’ between this centrality measure and actual flow. Rather than considering only the topological properties of a street network, we take into account two aspects, the spatial heterogeneity of human activities and the distance-decay law, to explain the observed traffic-flow distribution. The spatial distribution of human activities is estimated using mobile phone Erlang values, and the power law distance decay is adopted. We run Monte Carlo simulations to generate trips and predict traffic-flow distributions, and use a weighted correlation coefficient to measure the goodness of fit between the observed and the simulated data. The correlation coefficient achieves the maximum (0.623) when the exponent equals 2.0, indicating that the proposed model, which incorporates geographical constraints and human mobility patterns, can interpret urban traffic flow well.
The significance and vulnerability of Australian saltmarshes: implications for management in a changing climate
Authors: Saintilan Neil , Rogers Kerrylee
Published: February 2013

We review the distribution, status and ecology of Australian saltmarshes and the mechanisms whereby enhanced atmospheric carbon dioxide and associated climate change have influenced and will influence the provision of ecosystem goods and services. Research in temperate and subtropical saltmarsh has demonstrated important trophic contributions to estuarine fisheries, mediated by the synchronised mass-spawning of crabs, which feed predominantly on the C4 saltmarsh grass Sporobolus virginicus and microphytobenthos. Saltmarshes also provide unique feeding and habitat opportunities for several species of threatened microbats and birds, including migratory shorebirds. Saltmarshes increased in extent relative to mangrove in Australia in both tide- and wave-dominated geomorphic settings through the latter Holocene, although historic trends have seen a reversal of this trend. Australian saltmarshes have some capacity to maintain elevation with respect to rising sea level, although in south-eastern Australia, the encroachment of mangrove and, in Tasmania, conversion of shrubland to herbfield in the past half-century are consistent with changes in relative sea level. Modelling of the impacts of projected sea-level rise, incorporating sedimentation and other surface-elevation drivers, suggests that the survival of saltmarsh in developed estuaries will depend on the flexible management of hard structures and other impediments to wetland retreat.
Critical regulation of miR-200/ZEB2 pathway in Oct4/Sox2-induced mesenchymal-to-epithelial transition and induced pluripotent stem cell generation
Authors: Wang Guiying , Guo Xudong , Hong Wujun , Liu Qidong , Wei Tingyi , Lu Chenqi , Gao Longfei , Ye Dan , Zhou Yi , Chen Jie , Wang Jianmin , Wu Minjuan , Liu Houqi , Kang Jiuhong
Published: February 2013

Fibroblasts can be reprogrammed to induced pluripotent stem cells (iPSCs) by application of transcription factors octamer-binding protein 4 (Oct4), SRY-box containing gene 2 (Sox2), Kruppel-like factor 4 (Klf4), and c-Myelocytomatosis oncogene (c-Myc) (OSKM), but the underlying mechanisms remain unclear. Here, we report that exogenous Oct4 and Sox2 can bind at the promoter regions of mir-141/200c and mir-200a/b/429 cluster, respectively, and induce the transcription activation of miR-200 family during the OSKM-induced reprogramming. Functional suppression of miR-200s with specific inhibitors significantly represses the OSKM-caused mesenchymal-to-epithelial transition (MET, an early event in reprogramming of fibroblasts to iPSCs) and iPSC generation, whereas overexpression of miR-200s promotes the MET and iPSC generation. Mechanistic studies showed that miR-200s significantly repress the expression of zinc finger E-box binding homeobox 2 (ZEB2) through directly targeting its 3′ UTR and direct inhibition of ZEB2 can mimic the effects of miR-200s on iPSC generation and MET process. Moreover, the effects of miR-200s during iPSC generation can be blocked by ZEB2 overexpression. Collectively, our findings not only reveal that members of the miR-200 family are unique mediators of the reprogramming factors Oct4/Sox2, but also demonstrate that the miR-200/ZEB2 pathway as one critical mechanism of Oct4/Sox2 to induce somatic cell reprogramming at the early stage.
On the upper semicontinuity of pullback attractors for multi-valued processes
Authors: Wang Yejuan
Published: February 2013

This paper is concerned with the asymptotical behavior of multi-valued processes. First, we establish some stability results of pullback attractors for multi-valued processes and display new methods to check the continuity condition. Then we consider the effects of small time delays on the asymptotic stability of multi-valued nonautonomous functional parabolic equations. Finally, we give some new estimates of solutions and prove the existence of minimal pullback attractors in

H
0
1

(
Ω
)

H_0^1(\Omega )

for nonautonomous nonclassical diffusion equations with polynomial growth nonlinearity of arbitrary order and without the uniqueness of solutions. In particular, the upper semicontinuity of pullback attractors for nonclassical diffusion equations with singular and nonautonomous perturbations is addressed.
Critical residues in the PMEL/Pmel17 N-terminus direct the hierarchical assembly of melanosomal fibrils
Authors: Leonhardt Ralf M. , Vigneron Nathalie , Hee Jia Shee , Graham Morven , Cresswell Peter
Published: February 2013

PMEL (also called Pmel17 or gp100) is a melanocyte/melanoma-specific glycoprotein that plays a critical role in melanosome development by forming a fibrillar amyloid matrix in the organelle for melanin deposition. Although ultimately not a component of mature fibrils, the PMEL N-terminal region (NTR) is essential for their formation. By mutational analysis we establish a high-resolution map of this domain in which sequence elements and functionally critical residues are assigned. We show that the NTR functions in cis to drive the aggregation of the downstream polycystic kidney disease (PKD) domain into a melanosomal core matrix. This is essential to promote in trans the stabilization and terminal proteolytic maturation of the repeat (RPT) domain–containing MαC units, precursors of the second fibrillogenic fragment. We conclude that during melanosome biogenesis the NTR controls the hierarchical assembly of melanosomal fibrils.
Seasonal variation in telomere length of a hibernating rodent
Authors: Turbill Christopher , Ruf Thomas , Smith Steve , Bieber Claudia
Published: February 2013

Small hibernating rodents have greater maximum lifespans and hence appear to age more slowly than similar-sized non-hibernators. We tested for a direct effect of hibernation on somatic maintenance and ageing by measuring seasonal changes in relative telomere length (RTL) in the edible dormouse
Glis glis
. Average RTL in our population did not change significantly over the hibernation season, and a regression model explaining individual variation in post-hibernation RTL suggested a significant negative effect of the reduction in body mass over the inactive hibernation period (an index of time spent euthermic), supporting the idea that torpor slows ageing. Over the active season, RTL on average decreased in sub-adults but increased in adults, supporting previous findings of greater telomere shortening at younger ages. Telomere length increase might also have been associated with reproduction, which occurred only in adults. Our study reveals how seasonal changes in physiological state influence the progress of life-history traits, such as somatic maintenance and ageing, in a small hibernating rodent.
Infectious disease transmission as a forensic problem: who infected whom?
Authors: Teunis Peter , Heijne Janneke C. M. , Sukhrie Faizel , van Eijkeren Jan , Koopmans Marion , Kretzschmar Mirjam
Published: February 2013

Observations on infectious diseases often consist of a sample of cases, distinguished by symptoms, and other characteristics, such as onset dates, spatial locations, genetic sequence of the pathogen and/or physiological and clinical data. Cases are often clustered, in space and time, suggesting that they are connected. By defining kernel functions for pairwise analysis of cases, a matrix of transmission probabilities can be estimated. We set up a Bayesian framework to integrate various sources of information to estimate the transmission network. The method is illustrated by analysing data from a multi-year study (2002–2007) of nosocomial outbreaks of norovirus in a large university hospital in the Netherlands. The study included 264 cases, the norovirus genotype was known in approximately 60 per cent of the patients. Combining all the available data allowed likely identification of individual transmission links between most of the cases (72%). This illustrates that the proposed method can be used to accurately reconstruct transmission networks, enhancing our understanding of outbreak dynamics and possibly leading to new insights into how to prevent outbreaks.
A laboratory study of wave crest statistics and the role of directional spreading
Authors: Latheef M. , Swan C.
Published: February 2013

This paper concerns the crest height statistics arising in sea states that are broad banded in both frequency and direction. A new set of laboratory observations are presented and the results compared with the commonly applied statistical distributions. Taken as a whole, the data confirm that the crest-height distributions are critically dependent upon the directionality of the sea state. Although nonlinear effects arising at third order and above are most pronounced in uni-directional seas, the present data show that they are also important in directionally spread seas, provided the seas are sufficiently steep and not too short crested. The data also highlight the limiting effects of wave breaking. With individual breaking events dependent upon the local wave steepness, the directionality of the sea state again plays a significant role. Indeed, the present observations confirm that the two competing processes of nonlinear amplification and wave breaking can have a profound influence on the crest-height distributions leading to significant departures from established theory. In such cases, the key parameters are the sea state steepness and directional spread; the latter acting to counter the former in terms of nonlinear changes in the crest-height distributions.
Four barriers to the global understanding of biodiversity conservation: wealth, language, geographical location and security
Authors: Amano Tatsuya , Sutherland William J.
Published: February 2013

Global biodiversity conservation is seriously challenged by gaps and heterogeneity in the geographical coverage of existing information. Nevertheless, the key barriers to the collection and compilation of biodiversity information at a global scale have yet to be identified. We show that wealth, language, geographical location and security each play an important role in explaining spatial variations in data availability in four different types of biodiversity databases. The number of records per square kilometre is high in countries with high per capita gross domestic product (GDP), high proportion of English speakers and high security levels, and those located close to the country hosting the database; but these are not necessarily countries with high biodiversity. These factors are considered to affect data availability by impeding either the activities of scientific research or active international communications. Our results demonstrate that efforts to solve environmental problems at a global scale will gain significantly by focusing scientific education, communication, research and collaboration in low-GDP countries with fewer English speakers and located far from Western countries that host the global databases; countries that have experienced conflict may also benefit. Findings of this study may be broadly applicable to other fields that require the compilation of scientific knowledge at a global level.
Adaptive thermogenesis in adipocytes: Is beige the new brown?
Authors: Wu Jun , Cohen Paul , Spiegelman Bruce M.
Published: February 2013

One of the most promising areas in the therapeutics for metabolic diseases centers around activation of the pathways of energy expenditure. Brown adipose tissue is a particularly appealing target for increasing energy expenditure, given its amazing capacity to transform chemical energy into heat. In addition to classical brown adipose tissue, the last few years have seen great advances in our understanding of inducible thermogenic adipose tissue, also referred to as beige fat. A deeper understanding of the molecular processes involved in the development and function of these cell types may lead to new therapeutics for obesity, diabetes, and other metabolic diseases.
A Large-Scale Identification of Direct Targets of the Tomato MADS Box Transcription Factor RIPENING INHIBITOR Reveals the Regulation of Fruit Ripening
Authors: Fujisawa Masaki , Nakano Toshitsugu , Shima Yoko , Ito Yasuhiro
Published: February 2013

The fruit ripening developmental program is specific to plants bearing fleshy fruits and dramatically changes fruit characteristics, including color, aroma, and texture. The tomato (Solanum lycopersicum) MADS box transcription factor RIPENING INHIBITOR (RIN), one of the earliest acting ripening regulators, is required for both ethylene-dependent and -independent ripening regulatory pathways. Recent studies have identified two dozen direct RIN targets, but many more RIN targets remain to be identified. Here, we report the large-scale identification of direct RIN targets by chromatin immunoprecipitation coupled with DNA microarray analysis (ChIP-chip) targeting the predicted promoters of tomato genes. Our combined ChIP-chip and transcriptome analysis identified 241 direct RIN target genes that contain a RIN binding site and exhibit RIN-dependent positive or negative regulation during fruit ripening, suggesting that RIN has both activator and repressor roles. Examination of the predicted functions of RIN targets revealed that RIN participates in the regulation of lycopene accumulation, ethylene production, chlorophyll degradation, and many other physiological processes. Analysis of the effect of ethylene using 1-methylcyclopropene revealed that the positively regulated subset of RIN targets includes ethylene-sensitive and -insensitive transcription factors. Intriguingly, ethylene is involved in the upregulation of RIN expression during ripening. These results suggest that tomato fruit ripening is regulated by the interaction between RIN and ethylene signaling.
Combined effects of arthropod herbivores and phytopathogens on plant performance
Authors: Hauser Thure P. , Christensen Stina , Heimes Christine , Kiær Lars P.
Published: February 2013

Many plants are simultaneously attacked by arthropod herbivores and phytopathogens. These may affect each other directly and indirectly, enhancing or reducing the amount of plant resources they each consume. Ultimately, this may reduce or enhance plant performance relative to what should be expected from the added impacts of herbivore and pathogen when they attack alone.

Previous studies have suggested synergistic and antagonistic impacts on plant performance from certain combinations of arthropods and pathogens, for example, synergistic impacts from necrotrophic pathogens together with wounding arthropods because of facilitated infection and antagonistic impacts from induction of pathogen resistance by sucking herbivores.

We compiled published studies on the impact of plant–herbivore–pathogen interactions on plant performance and used meta‐analysis to search for consistent patterns of impacts among plant, herbivore and pathogen characteristics and experimental conditions, and to test the suggested hypotheses on synergistic or antagonistic impacts.

None of the hypotheses based on proximate interactions between arthropods and pathogens were supported by our analysis; in contrast, the patterns we found were related to plant traits and experimental conditions.

Our results suggest that immediate loss of resources from interactions between arthropod herbivores and pathogens is generally moderated by compensation to an extent where there are no interactive effects on plant performance. However, as interactive impacts also differed among environments and parasite manipulation methods, this suggests that the ability of plants to compensate such losses may depend on environmental conditions and probably also overall infection load.
Characterisation of two wheat enolase cDNA showing distinct patterns of expression in leaf and crown tissues of plants exposed to low temperature
Authors: Sharma P. , Ganeshan S. , Fowler D.B. , Chibbar R.N.
Published: February 2013

Seasonal low temperature (LT) adversely affects growth of plants. The onset of LT in temperate zones also entails the process of cold acclimation, preparing the plants to withstand freezing temperatures. During this process of cold acclimation a number of physiological, biochemical and molecular changes occur. A differentially expressed enolase gene in wheat plants exposed to LT was previously identified by cDNA‐amplified fragment length polymorphism. In this study, two wheat enolase cDNA, TaENO‐a and TaENO‐b amplified by 5′,3′ rapid amplification of cDNA end (RACE)‐PCR (polymerase chain reaction), were isolated and characterised. Quantitative real‐time PCR (QPCR) was done to assess their expression patterns in leaf and crown tissues of wheat plants exposed to LT. BLAST searches and bioinformatic analyses were done to determine the structure, domains and phylogeny of the cloned sequences. The two cDNA sequences differed mostly in the 5′ and 3′ untranslated regions. Deduced amino acid sequence showed high identity to bacteria, yeast, fungi, human and plant enolases with conserved putative DNA‐binding and repressor domains. A genomic clone containing 17 exons distributed over 4.5 kb structurally shared a high degree of similarity to rice enolase. QPCR revealed combined effects of LT and ageing on expression of TaENO‐a and TaENO‐b. Down‐regulation of TaENO‐a was observed with age in the crown tissues upon exposure to LT, but in leaf initial up‐regulation was followed by down‐regulation. Expression of TaENO‐b was similar to expression patterns previously reported for cold‐regulated (COR) genes in wheat, wherein the recessive vrnA‐1 allele influenced its expression in the leaf and genetic background determines its expression in the crown.
Decidual Regulatory T Cells in Placental Pathology and Pregnancy Complications
Authors: Quinn Kristen H. , Parast Mana M.
Published: February 2013

Regulatory T cells (Tregs) have been identified as immunomodulatory cells, which induce tolerance. Evidence from numerous recent studies implicates these cells as critical for maternal tolerance to the fetal‐derived placenta, proper functioning of which is required for normal gestation and growth and development of the fetus in utero. This review focuses on the recent studies of Tregs at the maternal–fetal interface in pregnancy complications, as well as their identification in specific inflammatory lesions in the placenta.
Understanding Autism and understanding my child with Autism: An evaluation of a group parent education program in rural Australia
Authors: Farmer Judy , Reupert Andrea
Published: February 2013

Objective

To describe and evaluate a six‐session program provided to parents of children with Autism in rural Australia. The program was designed to improve parent's knowledge and understanding of Autism, improve their confidence in managing their child and decrease parental anxiety.

Design

A self‐constructed questionnaire administered pre‐ and post‐intervention.

Setting

An early intervention centre in a large town in rural Victoria.

Participants

Ninety‐eight parents (or family members) of young children primarily aged 2–6 years of age, diagnosed with Autism.

Interventions

A ‘multi‐stranded content’ program was offered over six evenings. Ten programs were conducted over six years.

Results

The pre‐ versus post‐session analysis using a paired t‐test on matched person‐to‐person parental responses (n = 92) showed significant increases in parental understanding of Autism and understanding of their own child (P < 0.001), and in understanding the communication, sensory, social, learning and behavioural features of Autism (P < 0.001). Significant increases in parental confidence and a significant reduction in parental anxiety were also shown (P < 0.001). Qualitative data indicated that parents valued learning about the general nature of Autism and sensory processing, and reported feeling less alone.

Conclusions

The six‐week program was successful in terms of its aims. Parent feedback indicated that ongoing parent education sessions at regular intervals would enhance the impact of the program.
Commentary: Eyes wide shut in transnational science and aid
Authors: REDFIELD PETER
Published: February 2013

Responding to the problem of unknowing in the contemporary pursuit of knowledge, my commentary on Wenzel Geissler's article extends its themes to a parallel, overlapping domain of humanitarianism. The provision of medical aid shares the preference of research trials for an egalitarian style and similarly avoids recognizing the very inequities that structure its relations. The humanitarian embrace of exception and moral discourse likewise parallels the manner in which research partnerships elide obligation, emphasizing responsibility in terms of ethical regulation. When actors share a stake in not knowing, it complicates the critical task, requiring something other than simple unveiling.
Proxy citizenship and transnational advocacy: Colombian activists from Putumayo to Washington, DC
Authors: TATE WINIFRED
Published: February 2013

Proxy citizenship is the mechanism through which certain rights of citizenship—the ability to make claims for redress to a state—are conferred on activists through relationships with NGOs. Focusing on advocacy from within the policy process, U.S. and Colombian NGOs channeled political legitimacy and rights of access to Colombians, whose claims emerge from the experience of governance as articulated through testimony. This process, and its roots within the shared history of the Putumayo region of Colombia and Washington, DC, reveals emerging practices of citizenship claims and transnational political participation.
Living dangerously: Biopolitics and urban citizenship in Bogotá, Colombia
Authors: ZEIDERMAN AUSTIN
Published: February 2013

What happens when the rights of urban citizens are reconfigured by the biopolitical imperative to protect life from threats? I examine such situations by focusing on how the emergence of risk as a technique of government shapes urban politics in Bogotá, Colombia. Investigating the frames of political engagement within which claims for recognition, inclusion, and entitlement are made, I argue that it is within the domain of biopolitical security that poor and vulnerable populations engage in relationships with the state.
Bird flu biopower: Strategies for multispecies coexistence in Việt Nam
Authors: PORTER NATALIE
Published: February 2013

Outbreaks of SARS, swine flu, and avian influenza have prompted a “One Health” effort to control diseases transmitted between species. Using ethnographic observations from Việt Nam, I reveal how avian flu transforms strategies for living in light of human vulnerability to animals. Positing a multispecies approach to biopower, I argue that techniques for safeguarding human–animal collectivities confront heterogeneous moral codes surrounding animals’ role in knowledge hierarchies, village economies, and notions of individual worth. This analysis provides a framework for reconceptualizing biopower in relation to emerging diseases and reenvisions the role of animals in the politics of life itself.
Genetic variation and cognitive dysfunction one year after cardiac surgery
Authors: Stewart A. , Katznelson R. , Kraeva N. , Carroll J. , Pickworth T. , Rao V. , Djaiani G.
Published: February 2013

Various studies have implicated a potential association between candidate gene polymorphisms and postoperative cognitive dysfunction, yet corroborative studies are lacking. We investigated the variants in genes encoding platelet glycoprotein‐IIIa and apolipoprotein‐E and their relationship with postoperative cognitive dysfunction one year after cardiac surgery. A total of 155 patients were studied; neuropsychological testing demonstrated cognitive dysfunction in 31 (20%) patients at one‐year follow‐up. No differences were detected with respect to baseline characteristics, pre‐operative variables and surgical data between the patients with and without cognitive dysfunction. The PlA2‐allele of the platelet glycoprotein‐IIIa gene was present in 13 (42%) and 25 (20%) patients with and without cognitive dysfunction, respectively, p = 0.012. The apolipoprotein E‐ε4 allele was present in 9 (29%) and 24 (19%) patients with and without cognitive dysfunction, respectively, p = 0.24. Both the PlA2 and apolipoprotein‐ε4 alleles were present together in 6 (19%) and 5 (4%) patients with and without cognitive dysfunction, respectively, p = 0.003. Validation of these findings is required in age‐adjusted non‐surgical controls.
Neonatal alloimmune thrombocytopenia: pathogenesis, diagnosis and management
Authors: Peterson Julie A. , McFarland Janice G. , Curtis Brian R. , Aster Richard H.
Published: February 2013

Neonatal alloimmune thrombocytopenia, (NAIT) is caused by maternal antibodies raised against alloantigens carried on fetal platelets. Although many cases are mild, NAIT is a significant cause of morbidity and mortality in newborns and is the most common cause of intracranial haemorrhage in full‐term infants. In this report, we review the pathogenesis, clinical presentation, laboratory diagnosis and prenatal and post‐natal management of NAIT and highlight areas of controversy that deserve the attention of clinical and laboratory investigators.
TCTP increases stability of hypoxia‐inducible factor 1α by interaction with and degradation of the tumour suppressor VHL
Authors: Chen Ke , Chen Shuliang , Huang Chunhua , Cheng Hanhua , Zhou Rongjia
Published: February 2013

Background Information

The translationally controlled tumour protein (TCTP) plays an important role in maintaining cell proliferation and its high expression is associated with many tumours. The tumour suppressor von Hippel–Lindau protein (VHL) has been shown to function as an E3 ubiquitin ligase. Although great progress has been made, biological roles of these factors and relevant molecular mechanisms remain largely unknown.

Results

In this study, we have shown that TCTP specifically binds to VHL through its β domain and competes with hypoxia‐inducible factor‐1α (HIF1α). TCTP over‐expression decreased the protein level of VHL and the inhibition of TCTP expression by miRNA resulted in an increase of the VHL protein level. Moreover, TCTP over‐expression promoted the K48‐linked ubiquitination of VHL, thus degradation through the ubiquitin–proteasome pathway. In addition, we showed that TCTP increased the protein level of HIF1α, which promoted both vascular endothelial growth factor–hypoxic response element‐promoter‐driven luciferase reporter and endogenous VEGF expression.

Conclusions

These data have demonstrated that TCTP binds to the β domain of VHL through competition with HIF1α, which promotes VHL degradation by the ubiquitin–proteasome system and HIF1α stability.
Mosaicism in von Hippel–Lindau disease with severe renal manifestations
Authors: Wu P , Zhang N , Wang X , Li T , Ning X , Bu D , Gong K
Published: February 2013

von Hippel–Lindau (VHL) disease is an inheritable multisystem tumor syndrome characterized by multiple benign and malignant tumors affecting multiple organs. VHL is the result of a germline mutation in the VHL tumor suppressor gene. Molecular genomic analysis routinely confirms the clinical diagnosis. However, the use of molecular diagnostic methods can often be insufficient for the detection of mosaic germline VHL mutations, making the diagnosis of some cases of VHL difficult. Here, we report the case of a VHL mosaic patient with bilateral renal lesions in the absence of other VHL‐associated lesions. A VHL mutation was not originally detected by routine molecular testing. Nonetheless, the detection of a heterozygous c.194C>G (p.Ser65Trp) VHL mutation in the patient's daughter prompted further genetic assessment and eventually resulted in the finding of a mosaic c.194C>G (p.Ser65Trp) VHL mutation in the patient. The mutation rate was 18.8 ± 3.84% in peripheral leukocytes. As the frequency of VHL mosaicism remains underdetermined, the possibility of a diagnosis of mosaic VHL should be considered in patients with both typical and atypical VHL‐associated manifestations.
Liberty and the Post‐utilitarian Society
Authors: Saint‐Paul Gilles
Published: February 2013

Utilitarian foundations for limited government are shaky insofar as they assume rational and consistent individuals. Recently economists’ assumption of rational actors has come under sustained attack. Behavioural economics has suggested that people are plagued by irrational biases and inconsistencies. These developments have led to a post‐utilitarianism which is held to justify paternalistic interventions by the state via ‘sin taxes’, direct bans or new obligations. Individual responsibility is seriously undermined, as is faith in markets. Supporters of individual freedom need to move away from utilitarian reasoning, reassert core values of autonomy and responsibility, and define strict limits on the scope of government intervention.
International Terrorism, Domestic Political Instability, and the Escalation Effect
Authors: Campos Nauro F. , Gassebner Martin
Published: February 2013

What are the main causes of international terrorism? Despite the meticulous examination of various candidate explanations, existing estimates still diverge in sign, size, and significance. This article puts forward a novel explanation and supporting evidence. We argue that domestic political instability provides the learning environment needed to successfully execute international terror attacks. Using a yearly panel of 123 countries over 1973–2003, we find that the occurrence of civil wars increases fatalities and the number of international terrorist acts by 45%. These results hold for alternative indicators of political instability, estimators, subsamples, subperiods, and accounting for competing explanations.
The Effect of Political Alignment on Transfers to Portuguese Municipalities
Authors: Migueis Marco
Published: February 2013

I investigate if political alignment between central and local governments brings financial benefit to local governments, using financial data from Portuguese municipalities (1992–2005). I use regression discontinuity design to determine the effect of political alignment per se on transfers to municipalities. Municipalities aligned with the central government receive 19% more targetable transfers than unaligned municipalities. I test for electoral motivation of this transfer bias: extra transfers increase the vote share of incumbents in local elections for one of the two Portuguese major parties; however, municipal incumbency does not lead to better results in national elections.