bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of ionization and electron drift velocity profile to Rayleigh instability in a Hall thruster plasma
Authors: Singh Sukhmander , Malik Hitendra K.
Published: July 2012

Role of ionization to Rayleigh instability is clarified in a Hall thruster plasma under the variety of profiles of electron drift velocity, namely, step-like profile (SLP) and two different super-Gaussian profiles (SGP1 and SGP2). For this, a relevant Rayleigh equation is derived and solved numerically using fourth-order Runge-Kutta method. Interestingly, an upper cutoff frequency of oscillations ωmax is realized for the occurrence of the instability that shows dependence on the ionization rate α, electron drift velocity u0, electron cyclotron frequency Ω, azimuthal wave number ky, plasma density n0, density gradient ∂n0/∂x, ion (electron) thermal speed VthI(VthE), and ion (electron) plasma frequency ωpi(ωpe). The frequency ωmax follows the trend ωmax (for SGP2) >ωmax (for SLP) >ωmax (for SGP1) and shows a similar behaviour with ionization for all types of the velocity profiles. The instability is found to grow faster for the higher α and the ion temperature but it acquires lower rate under the effect of the higher electron temperature; the perturbed potential also varies in accordance with the growth rate. The electron temperature influences the growth rate and cutoff frequency less significantly in comparison with the ion temperature.
Determination of the thermal conductivity tensor of the n = 7 Aurivillius phase Sr4Bi4Ti7O24
Authors: Zurbuchen M. A. , Cahill D. G. , Schubert J. , Jia Y. , Schlom D. G.
Published: July 2012

A challenge in the preparation of advanced materials that exist only as thin films is to establish their properties, particularly when the materials are of low symmetry or the tensor properties of interest are of high rank. Using Sr4Bi4Ti7O24 as an example, we show how the preparation of oriented epitaxial films of multiple orientations enables the thermal conductivity tensor of this tetragonal material with a c-axis length of 64.7 Å to be measured. The thermal conductivity tensor coefficients k33 = 1.10 W m−1 K−1 and k11 = k22 = 1.80 W m−1 K−1 were determined by growing epitaxial Sr4Bi4Ti7O24 films on (100), (110), and (111) SrTiO3 substrates.
High operating temperature interband cascade midwave infrared detector based on type-II InAs/GaSb strained layer superlattice
Authors: Gautam Nutan , Myers S. , Barve A. V. , Klein Brianna , Smith E. P. , Rhiger D. R. , Dawson L. R. , Krishna S.
Published: July 2012

We report on an interband cascade mid-wave infrared (MWIR) detector based on type-II InAs/GaSb/AlSb strained layer superlattices (T2SL). The reported device has a seven-stage cascade region, each segment containing a MWIR absorber region, a graded T2SL transport region, and an interband tunneling region. Above room temperature spectral response was observed, with a cutoff wavelength of 7 μm at 420 K. Detailed radiometric measurements yielded a Johnson noise limited detectivity of 3.0 × 1011 cmHz1/2W−1 (8.9 × 108 cmHz1/2W−1) and a dark current density of 3.6 × 10−7 A/cm−2 (7.3 × 10−3 A/cm−2) near zero bias with a 100% cutoff wavelength of 5.2 μm and 6.2 μm at 77 K (295 K), respectively, with an estimated 36.2% QE.
Fluid-shear method to evaluate bacterial adhesion to glass surfaces
Authors: Zhou Yan , Torres Ashley , Chen Liangxian , Kong Ying , Cirillo Jeffrey D. , Liang H.
Published: July 2012

Adhered bacteria onto different surfaces cause infection that affects our health and environments. The understanding of the bacterial adhesive strength is crucial for better control and safe manufacturing in order to design adhesion resistant materials. The current evaluation methods lack precision and are often time consuming. In the present research, we developed a fluid-shear method to quantitatively evaluate bacterial adhesive strength on glass substrates. The glass was chosen based on its abundance in household, industrial, and medical environments. The fluid shear stress applied by a rheometer ranged from 0 to 3 Pa and the average surface roughness (Ra) of glass ranged from 1 to 23 nm. Bacterial adhesive stress was calculated based on the measurement of the critical radius. It was also found that the adhesive strength decreased with the increase of surface roughness, while the number of adhered bacteria increased when the surface become rougher. The fluid-shear method was proven to be effective in measure bacterial adhesion on a surface.
The ferromagnetic and antiferromagnetic phases in anion deficient La0.5−xPrxBa0.5CoO3−δ cobaltites
Authors: Troyanchuk I. O. , Karpinsky D. V. , Bushinsky M. V. , Sikolenko V. , Efimov V. , Cervellino A. , Raveau B.
Published: July 2012

Neutron powder diffraction studies of crystal and magnetic structures, magnetization and magnetotransport measurements have been performed for La0.5−xPrxBa0.5CoO3−δ (x≤0.375, δ<0.25) cobaltites. It has been found that the compositions (0≤x≤0.35) are cubic (Pm3m) whereas x=0.375 one is tetragonal (P4/mmm) due to an ordering of rare-earth and barium ions, while the oxygen vacancies are disordered. The oxygen content decrease leads to transformation of the magnetic structure from ferromagnetic to the G-type antiferromagnetic one through the mixed two-phase magnetic state. The compositions with antiferromagnetic component show structural phase separation, strong increase of the unit cell volume upon cooling, and anomalous magnetization behavior. It is suggested that these phenomena are associated with stabilization of Co3+ ions in high/low spin state at low temperature. The high/low spin state corresponds antiferromagnetic phase, whereas in the ferromagnetic one, the Co3+ and Co4+ ions adopt intermediate spin state.
Ultralow equivalent magnetic noise in a magnetoelectric Metglas/Mn-doped Pb(Mg1/3Nb2/3)O3-PbTiO3 heterostructure
Authors: Wang Yaojin , Gao Junqi , Li Menghui , Hasanyan D. , Shen Ying , Li Jiefang , Viehland D. , Luo Haosu
Published: July 2012

An ultralow equivalent magnetic noise of 6.2 pT/√Hz at 1 Hz was obtained in a bimorph heterostructure sensor unit consisting of longitudinal-magnetized Metglas layers and a transverse-poled 1 mol. % Mn-doped Pb(Mg1/3Nb2/3)O3-29PbTiO3 (PMN-PT) single crystal. Furthermore, the equivalent magnetic noise was ≤1 pT/√Hz at 10 Hz. Compared with previously reported multi-push-pull configuration Metglas/PMN-PT sensor units, the current heterostructure exhibits a higher magnetoelectric coefficient of 61.5 V/(cm × Oe), a similar equivalent magnetic noise at 1 Hz and a lower noise floor at several hertz range. The ultralow equivalent magnetic noise in this sensor unit is due to the low tangent loss and ultrahigh piezoelectric properties of Mn-doped PMN-PT single crystals.
Ambipolar acoustic transport in silicon
Authors: Barros A. D. , Batista P. D. , Tahraoui A. , Diniz J. A. , Santos P. V.
Published: July 2012

We have investigated the ambipolar transport of electrons and holes by electrically generated surface acoustic waves (SAWs) on silicon wafers coated with a piezoelectric ZnO film. The transport experiments were carried out by using a focused laser beam to optically excite carriers. The carriers are then captured by the moving SAW piezoelectric field and then transported towards a lateral p-i-n junction, where they are electrically detected. The piezoelectric modulation modifies the current vs. voltage characteristics of the lateral p-i-n junction. This behavior is accounted for by a simple model for the change of the junction potential by the SAW fields. We demonstrate that electrons and holes can be acoustically transported over distances approaching 100 μm, the transport efficiency being limited by the low mobility of holes in the material. These results open the way for silicon-based acousto-electric devices using ambipolar transport such as photo-detectors and solar cells.
Negative capacitance induced by redistribution of oxygen vacancies in the fatigued BiFeO3-based thin film
Authors: Ke Qingqing , Lou Xiaojie , Yang Haibo , Kumar Amit , Zeng Kaiyang , Wang John
Published: July 2012

The capacitance dispersion in La and Mg co-substituted BiFeO3 thin film has been studied at different stages of polarization switching. A negative capacitance (NC) behavior is observed in the sample that is fatigued above 109 switching cycles. The origin of the NC is investigated through analyzing relaxation processes and charge transport kinetics by admittance spectroscopy. An activation energy of ∼0.6 eV and a zero field mobility μ0=5.33±0.02×10−13m2/Vs are thus obtained. A physical mechanism is proposed to explain this behavior. It involves a redistribution of oxygen vacancies, which are trapped at the film/electrode interface during the fatigue process.
Structure refinement and dielectric relaxation of M-type Ba, Sr, Ba-Sr, and Ba-Pb hexaferrites
Authors: Ashima  , Sanghi Sujata , Agarwal Ashish , Reetu  , Ahlawat Neetu , Monica
Published: July 2012

M-type hexaferrites with compositions BaFe12O19 (BFO), SrFe12O19 (SFO), Ba0.5Sr0.5Fe12O19 (BSFO), and Ba0.5Pb0.5Fe12O19 (BPFO) were synthesized by commercial solid state reaction method. The Rietveld refinement of x-ray powder diffraction revealed a single hexagonal phase with space group P63/mmc for BFO, SFO, and BSFO samples, whereas BPFO sample contains hematite (α-Fe2O3) phase with space group R3c along with the M-type main phase. All the samples show dispersion in dielectric constant (ɛ′) and dielectric loss (tan δ) values with frequency. The values of ɛ′ and tan δ increase with increase in temperature due to increase in the number of charge carriers and their mobilities, which are thermally activated. The reciprocal temperature dependence of conductivity (σac) and the most probable relaxation time (τM″) satisfies the Arrhenius relation. A perfect overlapping of the normalized plots of modulus isotherms on a single “super curve” for all the studied temperatures reveals a temperature independence of dynamic processes involved in conduction and for relaxation. Further, the complex plots of M* (M″ vs M′) indicate that dc conductivity dominates in the region below the M″max point. Above M″max, the variations follow Jonscher power law (σ = Aωs) implying that ac conductivity is dominating in this region. Among the prepared samples, SFO hexaferrite has lowest values of σac, ɛ′, and tan δ making it suitable for use in microwave devices.
Thickness effects on the magnetic and electrical transport properties of highly epitaxial LaBaCo2O5.5+δ thin films on MgO substrates
Authors: Ma Chunrui , Liu Ming , Collins Gregory , Liu Jian , Zhang Yamei , Chen Chonglin , He Jie , Jiang Jiechao , Meletis Efstathios I.
Published: July 2012

The transport properties of double perovskite LaBaCo2O5.5+δ thin films with different thicknesses were systemically studied. A thin (7 nm in thickness), disordered LaBaCo2O5.5+δ layer was formed at the interface between the film and substrate. The films had a typical semiconductor behavior with antiferromagnetic and ferromagnetic behavior coexisting at low temperature. Although the Curie temperature was independent of the film thickness, the coercive fields and magnetizations increase with increasing the film thickness. An ultra large magnetoresistance effect value of about 44% was obtained at 60 K for the film of 82 nm.
Fully automatized quantum cascade laser design by genetic optimization
Authors: Bismuto A. , Terazzi R. , Hinkov B. , Beck M. , Faist J.
Published: July 2012

Using a transport model based on the density matrix formalism, a fully automatized technique to design quantum cascade structures in the mid-infrared is presented that implements a genetic algorithm where the wallplug efficiency has been used as merit factor. Starting from a reference design, the model converges after few generations on an optimized design that presents a better carrier injection in the upper lasing state. Both the designs have been fabricated using buried heterostructure process and the optimized design shows a pronounced increase in the laser operation range and higher output powers. In good agreement with the simulations, the laser efficiency increases from 5% to 12%.
Atomic and electronic structures of Zr-(Co,Ni,Cu)-Al metallic glasses
Authors: Yuan C. C. , Shen X. , Cui J. , Gu L. , Yu R. C. , Xi X. K.
Published: July 2012

The atomic and electronic structures of transition metal-metalloid based Zr60Co(Ni,Cu)28Al12 bulk metallic glasses (MGs) are probed by 27Al nuclear magnetic resonance (NMR) spectroscopy. The magnitude and evolution of 27Al isotropic shifts indicate that the Fermi level moves toward a minimum upon transition metal 3d sub-band filling and provides experimental evidence for pd hybridization bonding mechanism, which is further supported by the observation of Co L23 edges, and the prepeaks near Al L23 and K edges in electron energy loss spectroscopy. This investigation provides insight into the bonding mechanisms in MGs, which are relevant for understanding of their mechanical behaviors.
Directional anemometer based on an anisotropic flat-clad tapered fiber Michelson interferometer
Authors: Lee Cheng-Ling , Lee Chung-Fen , Li Chai-Ming , Chiang Tsai-Ching , Hsiao Ying-Li
Published: July 2012

This work demonstrates a sensitive directional anemometer that is based on a pendulum-type of anisotropic flat-clad tapered fiber Michelson interferometer (AFCTFMI). The AFCTFMI is fabricated by tapering an anisotropic flat-cladding fiber to establish structural anisotropy, and enables the sensing of the direction and magnitude of flowing air (wind). Wavelength shifts and fringes visibility of the measured interference fringes are correlated with the magnitude and furthermore the direction of the wind. Experimental results agree closely with the theoretical analysis. The directional anemometer can simultaneously and effectively indicate the direction, and sensitively measure the magnitude of wind.
Negative refraction and partial focusing with a crossed wire mesh: Physical insights and experimental verification
Authors: Morgado Tiago A. , Marcos João S. , Maslovski Stanislav I. , Silveirinha Mário G.
Published: July 2012

We experimentally verify that a flat metamaterial lens formed by nonconnected crossed metallic wires enables the partial focusing of electromagnetic waves, as a consequence of the phenomenon of all-angle broadband negative refraction in such media. We prove that the strength of the negative refraction effect can be controlled by adjusting the angle between the crossed wires.
Terahertz intracavity generation from output coupler consisting of stacked GaP plates
Authors: Zhao Pu , Ragam Srinivasa , Ding Yujie J. , Zotova Ioulia B.
Published: July 2012

We demonstrate intracavity terahertz generation from an output coupler of a compact dual-frequency solid state laser. The output coupler consisting of unbonded and stacked GaP plates is used as a second-order nonlinear medium where the difference-frequency generation takes place. When quasi-phase matching is achieved within the alternatively rotated GaP plates, terahertz output power is significantly enhanced compared with that for the corresponding external-cavity configuration.
Long minority carrier lifetime in Au-catalyzed GaAs/AlxGa1−xAs core-shell nanowires
Authors: Jiang N. , Parkinson P. , Gao Q. , Breuer S. , Tan H. H. , Wong-Leung J. , Jagadish C.
Published: July 2012

GaAs/AlxGa1−xAs core-shell nanowires were grown by metal organic chemical vapor deposition with optimized AlxGa1−xAs shell and twin-free Au-catalyzed GaAs cores. Time-resolved photoluminescence measurements were carried out on single nanowires at room temperature, revealing minority carrier lifetimes of 1.02 ± 0.43 ns, comparable to self-assisted nanowires grown by molecular beam epitaxy. The long minority carrier lifetimes are mainly attributed to improvement of the GaAs/AlxGa1−xAs interface quality. The upper limit of surface recombination velocity of the structure is calculated to be 1300 cm/s with the AlxGa1−xAs shell grown at 750 °C, which is comparable with planar double heterostructures.
Time resolved optical emission images of an atmospheric pressure plasma jet with transparent electrodes
Authors: Puač N. , Maletić D. , Lazović S. , Malović G. , Đorđević A. , Petrović Z. Lj.
Published: July 2012

We study development of plasma packages in atmospheric pressure plasma jet from their formation as a discharge close to the instantaneous cathode, following their motion between and inside the electrodes up to their emergence at the edge of the glass tube and formation of a plasma bullet. Inside both electrodes, plasma is concentrated close to the walls and is bright, while outside it is located at the axis. This paper opens issues of the geometry of electrodes, fields, and atomic processes, allowing some predictions to be made about pertinent mechanisms.
Transport, thermoelectric, and magnetic properties of a dense Cr2S3 ceramic
Authors: Maignan A. , Bréard Y. , Guilmeau E. , Gascoin F.
Published: July 2012

By using the spark plasma sintering technique, a dense Cr2S3−x ceramic, crystallizing in the trigonal P3¯1c space group of Cr2S3, has been prepared by starting from a powder of R3¯ Cr2S3 precursor. The Cr and S contents of the densified sample deviate from the 2/3 ratio, indicating the presence of extra Cr at the level of the deficient “Cr1/3S” layer of the Cr2S3 structure, thus leading to the Cr2S2.8 formula. In contrast to the large magnetoresistance associated to the ferromagnetic-like component in the stoichiometric rhombohedral precursor, no significant negative magnetoresistance could be measured in the trigonal, sulfur deficient, Cr2S3. However, the non stoichiometry and the densification induce a higher charge carrier concentration and a reduced contribution of the grain boundaries, respectively. This explains the low resistivity value, ρ300 K = 2.65 mΩ · cm. With the thermal conductivity remaining below 2 W · m−1K−1 up to 700 K, a thermoelectric figure of merit reaching zT = 0.12 at 675 K is achieved.
High power microwave generation from the low-impedance transit-time oscillator without foils
Authors: Cao Yibing , He Juntao , Zhang Jiande , Zhang Qiang , Ling Junpu
Published: July 2012

A low-impedance transit-time oscillator without foils (LITTO) has been proposed in our previous work. Recently, the experiment is carried out on an intense relativistic electron beam (IREB) generator, which is capable of producing a 50 ns duration electron beam in the voltage range of 0.4-1 MV. With a 600 kV, 24 kA electron beam guided by an external magnetic field of 0.5 T, a radiation power of 2.7 GW at 1.64 GHz has been achieved and the corresponding power conversion efficiency is 18.75%. With the similar voltage and current parameters, the experimental results are reexamined and confirmed by the particle-in-cell (PIC) simulation.
Field-aligned accelerations by plasma shocks propagating through interstellar magnetic fields
Authors: Takeuchi Satoshi
Published: July 2012

A kinetic model of particle acceleration by plasma shocks is analyzed theoretically and with numerical calculations. The shocks are propagating through weakly magnetized background plasmas, namely interstellar magnetic fields (IMFs). Particles located at the shock front are accelerated parallel to the magnetic field of the shock; this is defined as the field-aligned acceleration (FAA). The cross angle between IMF and the magnetic field of the shock plays an important role in creating the magnetic neutral sheet at the shock front. A test particle trapped by the neutral sheet obtains enormous energy due to the FAA. A reasonable formula for the highest energy gain is derived from theoretical analysis of the relativistic equations of motion. A possible configuration of the electric and magnetic fields in supernova remnants is also proposed by way of example.
Does carcass suspension technique influence reindeer (Rangifer tarandus tarandus) meat quality attributes?
Authors: Wiklund E. , Finstad G. , Aguiar G. , Bechtel P. J.
Published: July 2012

In total, eight reindeer steers (ages 3–6 years old) were used in the study to evaluate the effects of carcass suspension technique on meat tenderness, colour and water-holding capacity (WHC). Carcasses were split along the spine and sides were randomly allocated to pelvic suspension (hung using a butcher hook through the obturator foramen) or normal Achilles tendon suspension (control treatment). From all 16 carcass halves, meat samples were collected from the loin (M. longissimus), inside (M. semimembranosus) and shoulder (M. triceps brachii) for sensory evaluation and measurements of shear force (tenderness). Loin samples were also evaluated for meat colour at 1 day after slaughter and for purge (WHC) after vacuum-packaged chilled storage (+2°C) for 1, 2 and 3 weeks. No significant effects of carcass suspension technique were found for reindeer meat colour and WHC (purge). Shear force values for loin samples from pelvic-suspended carcasses were significantly (P = 0.001) lower than those from Achilles tendon-suspended carcasses, and there was a similar trend for inside samples, although this was not significant (P = 0.06). There was no effect of carcass suspension technique for shear force values of the shoulder samples. The trained panel judged loin and inside samples from pelvic-suspended carcasses to be more tender (P ≤ 0.001) while no effect of carcass suspension technique on tenderness was found in the shoulder samples. Juiciness was not affected by carcass suspension. The present study demonstrated that pelvic suspension improved tenderness in the most valuable cuts from the reindeer carcass (loin and inside).
Effects of dietary protein levels on production performance and serum insulin-like growth factor-1 levels in sika deer
Authors: Yang Fuhe , Gao Xiuhua , Li Guangyu
Published: July 2012

The purpose of this study was to investigate the influence of dietary protein levels on the performance of sika deer. Twenty-four male sika deer were randomly assigned into three treatments, where they were fed a diet containing either 12, 16 or 20% crude protein (CP). During the antler growth period the average bodyweight gain in 12, 16 and 20% CP levels was 17.3, 19.9 and 14.4 kg, respectively; antler yield was 2224, 2518 and 2246 g, respectively. A significant positive relationship (P < 0.01) was found between serum insulin-like growth factor (IGF)-I concentration and bodyweight gain (P < 0.01) and antler yield (P < 0.01), using the regression equations: bodyweight gain (kg) = 0.06IGF-1 (ng/mL) – 52.14 (R2 = 0.69, n = 8) and antler yield (g) = 3.55IGF-1 (ng/mL) – 1659.4 (R2 = 0.77, n = 8), respectively. We concluded that 16% dietary protein was optimal for bodyweight gain and antler yield during the antler growth period in the sika deer.
An optimal habitat model for the white-tailed deer (Odocoileus virginianus) in central Veracruz, Mexico
Authors: Bolívar-Cimé B. , Gallina S.
Published: July 2012

Modelling wildlife habitat availability for animal species has important implications for explaining the distribution of the animals in the wild, their effective management and conservation. In this study we evaluated an Optimal Habitat Model based on the Habitat Suitability Index (HSI) for the white-tailed deer (Odocoileus virginianus) in central Veracruz, Mexico. We generated a GIS-based model from the main habitat requirements that influence the presence of white-tailed deer. Six variables were used for modelling the optimal habitat. With these data layers we calculated the HSI for deer in the study area. Two strip transects (500 by 2 m) were set up at 18 sites where all signs of white-tailed deer were recorded. The HSI for the study area ranged from –0.667 to 0.905, with the lowest values associated with poor habitat quality. Eighty-six percent of the study area’s surface was habitat of intermediate and low quality. Seventy percent of the deer signs were found in intermediate habitat quality. White-tailed deer frequently used oak forest, tropical deciduous forest and pastures. A Classification Tree Analysis indicated that temperature and aspect were the main habitat features influencing white-tailed deer presence. Although anthropogenic pressure in the region is high, forest patches help maintain some suitable habitat for small populations of this species. Conservation and restoration of the vegetation cover is recommended to promote the recovery of deer populations in central Veracruz, Mexico.
Seasonal and specific diet variations in sympatric red and fallow deer of southern Spain: a preliminary approach to feeding behaviour
Authors: Azorit C. , Tellado S. , Oya A. , Moro J.
Published: July 2012

We studied the diet composition and diet overlap in sympatric red deer (Cervus elaphus hispanicus) and fallow deer (Dama dama) throughout a whole year in order to determine variation due to season, species, sex and age class by analysing rumen contents samples of 81 red and 69 fallow deer shot monthly during 2008–09 in Sierra de Andújar Natural Park, southern Spain. We assessed diet similarity and possible inter- and intra-specific foraging competition. We found different foraging strategies for both species and sexes during constraint periods, and several theoretical considerations of specific interactions and behaviour are discussed with respect to the Mediterranean environment. In both species an annual diet dominated by grasses was recorded, peaking in spring. Browses were an important food resource at the end of winter and at the end of summer, and fruit more in autumn and winter. Red deer ingested a higher proportion of browse than fallow deer, which consumed more acorns and for a longer time showed a better ability to compensate for nutritional constraint periods. An overall decline in diet similarity in summer and at the end of winter led us to assume that exploitative competition between red and fallow deer and even between sexes was probable. Red deer females showed low diet similarity to other deer, while there was a great diet overlap between red deer males and fallow deer females at the end of summer. Differences detected between both two species and sexes do not always support predictions deriving from specific body size and morpho-physiological characteristics, but can probably be explained as a consequence of different metabolic demands. The relationship between plant nutritional attributes and food selection according to reproductive or physiological status and seasonal demands for both sexes and species should be researched in order to perform a better assessment of deer feeding behaviour.
Tmem100
, an ALK1 receptor signaling-dependent gene essential for arterial endothelium differentiation and vascular morphogenesis
Authors: Somekawa Satoshi , Imagawa Keiichi , Hayashi Hisaki , Sakabe Masahide , Ioka Tomoko , Sato Genki E. , Inada Ken , Iwamoto Takaaki , Mori Toshio , Uemura Shiro , Nakagawa Osamu , Saito Yoshihiko
Published: July 2012

Members of the transforming growth factor-β superfamily play essential roles in various aspects of embryonic development and physiological organ function. Among them, bone morphogenetic protein (BMP) 9 and BMP10 regulate embryonic vascular development by activating their endothelial receptor ALK1 (activin receptor-like kinase 1, also called Acvrl1). ALK1-mediated intracellular signaling is implicated in the etiologies of human diseases, but their downstream functional proteins are largely unknown. In this study, we identified
Tmem100
, a gene encoding a previously uncharacterized intracellular transmembrane protein, to be an embryonic endothelium-enriched gene activated by BMP9 and BMP10 through the ALK1 receptor.
Tmem100
null mice showed embryonic lethality due to impaired differentiation of arterial endothelium and defects of vascular morphogenesis, which phenocopied most of the vascular abnormalities observed with the
Acvrl1/Alk1
deficiency. The activity of Notch- and Akt-mediated signaling, which is essential for vascular development, was down-regulated in
Tmem100
null mice.
Cre
-mediated deletion of
Tmem100
in endothelial cells was sufficient to recapitulate the null phenotypes. These data indicated that TMEM100 may play indispensable roles downstream of BMP9/BMP10-ALK1 signaling during endothelial differentiation and vascular morphogenesis.
Modeling huanglongbing transmission within a citrus tree
Authors: Chiyaka Christinah , Singer Burton H. , Halbert Susan E. , Morris J. Glenn , van Bruggen Ariena H. C.
Published: July 2012

The citrus disease huanglongbing (HLB), associated with an uncultured bacterial pathogen, is threatening the citrus industry worldwide. A mathematical model of the transmission of HLB between its psyllid vector and citrus host has been developed to characterize the dynamics of the vector and disease development, focusing on the spread of the pathogen from flush to flush (a newly developing cluster of very young leaves on the expanding terminal end of a shoot) within a tree. This approach differs from that of prior models for vector-transmitted plant diseases where the entire plant is the unit of analysis. Dynamics of vector and host populations are simulated realistically as the flush population approaches complete infection. Model analysis indicates that vector activity is essential for initial infection but is not necessary for continued infection because infection can occur from flush to flush through internal movement in the tree. Flush production, within-tree spread, and latent period are the most important parameters influencing HLB development. The model shows that the effect of spraying of psyllids depends on time of initial spraying, frequency, and efficacy of the insecticides. Similarly, effects of removal of symptomatic flush depend on the frequency of removal and the time of initiation of this practice since the start of the epidemic. Within-tree resistance to spread, possibly affected by inherent or induced resistance, is a major factor affecting epidemic development, supporting the notion that alternate routes of transmission besides that by the vector can be important for epidemic development.
Comparing Multiple Predictors of Energy Content in Juvenile Bluefish
Authors: Morley James W. , Buckel Jeffrey A. , Lankford Thomas E.
Published: July 2012

The need to estimate energetic status in fish is common, but determining energy content is costly. We examined the relationship between the energy density of wild juvenile bluefish Pomatomus saltatrix (115–310 mm) and multiple indicators of energetic status to develop regression models for predicting bluefish energy content. Energy density was strongly related to the percent dry mass of whole fish (r2 = 0.99) but poorly related to residual wet mass (r2 = 0.33), a commonly used condition index. Energy density was related to three hepatosomatic indices: liver wet mass (r2 = 0.45), liver dry mass (r2 = 0.64), and liver energy content (r2 = 0.70). Energy density was nonlinearly related to percent dry weight in muscle tissue (r2 = 0.93) and energy density in muscle tissue (r2 = 0.83). A biphasic pattern of lipid storage was found in muscle tissue, with very little lipid stored until after a threshold in percent dry weight is exceeded. Using our predictive equation, the energy content in whole bluefish can be determined using the percent dry weight of muscle tissue. However, our predictive model should only be used for wild‐caught bluefish because laboratory‐held fish exhibited higher lipid : protein ratios in muscle tissue.
Effect of externally applied resonant magnetic perturbations on resistive tearing modes
Authors: Hu Qiming , Yu Q. , Rao Bo , Ding Yonghua , Hu Xiwei , Zhuang Ge
Published: July 2012

Static resonant magnetic perturbations (RMPs) generated by saddle coil current have been applied in J-TEXT tokamak experiments in order to study their effects on tearing mode instabilities. With increasing RMP amplitude in time during the discharge, the mode stabilization is first observed, but a large locked mode follows if the RMP amplitude is increased to a very large value, indicating that the RMP amplitude is important in determining the plasma response and the tearing mode behaviour. By careful adjustment of the RMP amplitude, the (partial) stabilization of the m/n = 2/1 tearing mode by RMPs of moderate amplitude has been achieved without causing mode locking (m and n are the poloidal and toroidal mode numbers). To compare with experimental results, nonlinear numerical modelling based on reduced MHD equations has been carried out. With experimental parameters as input, both the mode locking and mode stabilization by RMPs are also obtained from numerical modelling. Further calculations have been carried out to study the plasma parameters affecting the mode stabilization by RMPs, including the plasma rotation frequency, viscosity, Alfvén velocity and the RMP amplitude. It is found that the suppression of the tearing mode by RMPs of moderate amplitude is possible for a sufficiently high ratio of plasma rotation velocity to the Alfvén speed. A larger plasma viscosity enhances the mode stabilization.
How Package Design and Packaged‐based Marketing Claims Lead to Overeating
Authors: Chandon Pierre
Published: July 2012

Because packaging reaches consumers at the critical moments of purchase and consumption, it has become an important marketing tool for food manufacturers and retailers. In this paper, I first review how the marketing, health and nutrition claims made on packaging create “health halos” that make foods appear healthier than they are, thereby leading to higher consumption yet lower perceived calorie intake. I then show how packaging design (cues, shapes, and sizes) biases people's perception of quantity and increases their preference for supersized packages and portions that appear smaller than they are. Finally, I examine the extent to which mandatory nutrition labels, stricter regulation of package claims, public promotion of mindful eating, and mindless eating nudges could limit the biasing effects of packaging on food perceptions and preferences.
CytoSPADE: high-performance analysis and visualization of high-dimensional cytometry data
Authors: Linderman Michael D. , Bjornson Zach , Simonds Erin F. , Qiu Peng , Bruggner Robert V. , Sheode Ketaki , Meng Teresa H. , Plevritis Sylvia K. , Nolan Garry P.
Published: July 2012

Motivation: Recent advances in flow cytometry enable simultaneous single-cell measurement of 30+ surface and intracellular proteins. CytoSPADE is a high-performance implementation of an interface for the Spanning-tree Progression Analysis of Density-normalized Events algorithm for tree-based analysis and visualization of this high-dimensional cytometry data.

Availability: Source code and binaries are freely available at http://cytospade.org and via Bioconductor version 2.10 onwards for Linux, OSX and Windows. CytoSPADE is implemented in R, C++ and Java.

Contact:  michael.linderman@mssm.edu

Supplementary Information: Additional documentation available at http://cytospade.org.
Heart failure in severe aortic valve stenosis: prognostic impact of left ventricular ejection fraction and mean gradient on outcome after transcatheter aortic valve implantation
Authors: Gotzmann Michael , Rahlmann Pia , Hehnen Tobias , Müller Patrick , Lindstaedt Michael , Mügge Andreas , Ewers Aydan
Published: July 2012

Aims

This prospective study aimed to evaluate the prognostic impact of left ventricular ejection fraction (LVEF) and aortic mean gradient patterns on outcome after transcatheter aortic valve implantation (TAVI).

Methods and results

From 2008 to 2011, 202 consecutive patients with severe symptomatic aortic valve stenosis (aortic valve area <1.0 cm2) were submitted to TAVI. Patients were divided into four groups according to LVEF (>50% vs. ≤50%) and aortic mean pressure gradient (>40 mmHg vs. ≤40 mmHg): group 1, preserved LVEF/high gradient (n = 86); group 2, preserved LVEF/low gradient (n = 27); group 3, reduced LVEF/high gradient (n = 45); and group 4, reduced LVEF/low gradient (n = 44). A CoreValve prosthesis (Medtronic, Minneapolis, MN, USA) was inserted retrogradely. Echocardiography was performed before and 1 year after TAVI. The primary study endpoint (1‐year all‐cause mortality) was reached in 47 patients (23%). All‐cause mortality was lowest in group 1 (14%), intermediate in group 2 (22%) and group 3 (27%), and highest in group 4 (39%) (P = 0.007). In survivors, aortic mean gradient decreased in all patients (baseline 48 ± 13 mmHg vs. 10 ± 4 mmHg at 1 year, P < 0.001). LVEF improved in group 3 and group 4 (baseline 42 ± 8% vs. 51 ± 11% at 1 year, P < 0.001).

Conclusion

Severe aortic stenosis with low gradient and/or reduced LVEF is associated with worse outcome after TAVI compared with aortic stenosis with preserved LVEF/high gradient. The evaluation of these haemodynamic parameters may help to improve risk stratification in patients undergoing TAVI.
First Report of Raspberry bushy dwarf virus Infecting Grapevine in Hungary
Authors: Pleško I. Mavrič , Marn M. Viršček , Nyerges K. , Lázár J.
Published: July 2012

Raspberry bushy dwarf virus (RBDV) is the sole member of genus Idaeovirus and naturally infects Rubus species worldwide. It can be experimentally transmitted to many dicotyledonous plant species from different families. In Slovenia it has been reported to naturally infect grapevine, the first known non-Rubus natural host (3). However, RBDV from red raspberry and grapevine were found to be different in biological, serological, and molecular characteristics (4). From 2007 to 2010, grapevine (Vitis vinifera L.) vineyards were sampled in different parts of Hungary and tested for RBDV infection by double antibody sandwich (DAS)-ELISA using commercial reagents (Bioreba, Reinach, Switzerland). Overall, 181 samples were collected from 10 vineyards around Csörnyeföld, Badacsony, Eger, Tolcsva (Orémus), and Nagyréde. Samples were taken randomly unless plants showing virus-like symptoms were present, which were preferentially included in the survey. Two samples collected in 2010, each consisting of five leaves from five individual plants, tested positive by DAS-ELISA. They originated from a small private vineyard of Italian Riesling, Pinot Gris, and Rhein Riesling in the southwestern part of Hungary near Csörnyeföld where 29 samples were collected. All leaves were asymptomatic. Total RNA was extracted from positive samples using a RNeasy Plant Mini Kit (Qiagen, Hilden, Germany). cDNA was synthesized using primer RNA12 as described (4) and further amplified by PCR using primers RBDVUP1/RBDVLO4 that amplified an 872-bp fragment of RBDV coat protein and 3′ non-translated region (2). Amplification products from both samples were directly sequenced (Macrogen, Seoul, Korea). The sequences showed 98.6% identity between each other and were deposited in GenBank (Accession Nos. JQ928628 and JQ928629). Sequences were also compared with RBDV sequences deposited in GenBank. They showed 97.7 to 99.3% identity with RBDV sequences from grapevine from Slovenia and 94.2 to 96.1% with RBDV sequences from Rubus sp. Natural infection of grapevine with RBDV was first reported from Slovenia in 2003 (3) and was recently reported also from Serbia (1). To our knowledge, this is the first report of RBDV infection of grapevine in Hungary and suggests a wider presence of the virus in the region.

References: (1) D. Jevremovic and S. Paunovic. Pestic. Phytomed. (Belgrade) 26:55, 2011. (2) H. I. Kokko et al. BioTechniques 20:842, 1996. (3) I. Mavric Pleško et al. Plant Dis. 87:1148, 2003. (4) I. Mavric Pleško et al. Eur. J. Plant Pathol. 123:261, 2009.
Climate change and marine life
Authors: Richardson Anthony J. , Brown Christopher J. , Brander Keith , Bruno John F. , Buckley Lauren , Burrows Michael T. , Duarte Carlos M. , Halpern Benjamin S. , Hoegh-Guldberg Ove , Holding Johnna , Kappel Carrie V. , Kiessling Wolfgang , Moore Pippa J. , O'Connor Mary I. , Pandolfi John M. , Parmesan Camille , Schoeman David S. , Schwing Frank , Sydeman William J. , Poloczanska Elvira S.
Published: July 2012

A Marine Climate Impacts Workshop was held from 29 April to 3 May 2012 at the US National Center of Ecological Analysis and Synthesis in Santa Barbara. This workshop was the culmination of a series of six meetings over the past three years, which had brought together 25 experts in climate change ecology, analysis of large datasets, palaeontology, marine ecology and physical oceanography. Aims of these workshops were to produce a global synthesis of climate impacts on marine biota, to identify sensitive habitats and taxa, to inform the current Intergovernmental Panel on Climate Change (IPCC) process, and to strengthen research into ecological impacts of climate change.
Proof of principle study of ultrasonic particle manipulation by a circular array device
Authors: Grinenko Alon , Wilcox Paul D. , Courtney Charles R. P. , Drinkwater Bruce W.
Published: July 2012

A feasibility study of a circular ultrasonic array device for acoustic particle manipulation is presented. A general approach based on Green's function is developed to analyse the underlying properties of a circular acoustic array. It allows the size of a controllable device area as a function of the number of array elements to be established and the array excitation required to produce a desired field distribution to be determined. A set of quantitative parameters characterizing the complexity of the pressure landscape is suggested, and relation to the number of array elements is found. Next, a finite-element model of a physically realizable circular piezo-acoustic array device is employed to demonstrate that the trapping capability can be achieved in practice.
Mistletoe as a keystone resource: an experimental test
Authors: Watson David M. , Herring Matthew
Published: July 2012

Various entities have been designated keystone resources, but few tests have been attempted and we are unaware of any experimental manipulations of purported keystone resources. Mistletoes (Loranthaceae) provide structural and nutritional resources within canopies, and their pervasive influence on diversity led to their designation as keystone resources. We quantified the effect of mistletoe on diversity with a woodland-scale experiment, comparing bird diversities before and after all mistletoe plants were removed from 17 treatment sites, with those of 11 control sites and 12 sites in which mistletoe was naturally absent. Three years after mistletoe removal, treatment woodlands lost, on average, 20.9 per cent of their total species richness, 26.5 per cent of woodland-dependent bird species and 34.8 per cent of their woodland-dependent residents, compared with moderate increases in control sites and no significant changes in mistletoe-free sites. Treatment sites lost greater proportions of birds recorded nesting in mistletoe, but changes in species recorded feeding on mistletoe did not differ from control sites. Having confirmed the status of mistletoe as a keystone resource, we suggest that nutrient enrichment via litter-fall is the main mechanism promoting species richness, driving small-scale heterogeneity in productivity and food availability for woodland animals. This explanation applies to other parasitic plants with high turnover of enriched leaves, and the community-scale influence of these plants is most apparent in low productivity systems.
Superinfection and the evolution of resistance to antimalarial drugs
Authors: Klein Eili Y. , Smith David L. , Laxminarayan Ramanan , Levin Simon
Published: July 2012

A major issue in the control of malaria is the evolution of drug resistance. Ecological theory has demonstrated that pathogen superinfection and the resulting within-host competition influences the evolution of specific traits. Individuals infected with
Plasmodium falciparum
are consistently infected by multiple parasites; however, while this probably alters the dynamics of resistance evolution, there are few robust mathematical models examining this issue. We developed a general theory for modelling the evolution of resistance with host superinfection and examine: (i) the effect of transmission intensity on the rate of resistance evolution; (ii) the importance of different biological costs of resistance; and (iii) the best measure of the frequency of resistance. We find that within-host competition retards the ability and slows the rate at which drug-resistant parasites invade, particularly as the transmission rate increases. We also find that biological costs of resistance that reduce transmission are less important than reductions in the duration of drug-resistant infections. Lastly, we find that random sampling of the population for resistant parasites is likely to significantly underestimate the frequency of resistance. Considering superinfection in mathematical models of antimalarial drug resistance may thus be important for generating accurate predictions of interventions to contain resistance.
Split‐dose administration of thiopurine drugs: a novel and effective strategy for managing preferential 6‐MMP metabolism
Authors: Shih D. Q. , Nguyen M. , Zheng L. , Ibanez P. , Mei L. , Kwan L. Y. , Bradford K. , Ting C. , Targan S. R. , Vasiliauskas E. A.
Published: July 2012

Background

Mercaptopurine and azathioprine (AZA) are efficacious in treating IBD. 6‐tioguanine (6‐TGN) levels correlate with therapeutic efficacy, whereas high 6‐methylmercaptopurine (6‐MMP) levels are associated with hepatotoxicity and myelotoxicity. Some IBD patients exhibit dose‐limiting preferential 6‐MMP production, which may lead to undesired side effects and impact efficacy.

Aim

To review the outcomes of thiopurine split‐dosing in patients with preferential 6‐MMP metabolism.

Methods

A retrospective chart review of 179 IBD patients treated at the Cedars‐Sinai IBD Center with AZA or mercaptopurine was performed. Preferential 6‐MMP metabolisers with 6‐MMP levels greater than 7000 pmol/8 × 108 erythrocytes who underwent split‐dosing were identified and assessed for biochemical and clinical responses to these dose modifications.

Results

A total of 20 of 179 patients met the criteria for preferential 6‐MMP metabolism and underwent thiopurine split‐dosing. Dividing the total daily thiopurine dose led to a reduction in 6‐MMP levels (11785 vs. 5324 pmol/8 × 108 erythrocytes; P < 0.0001) without negatively affecting clinical disease activity or 6‐TGN levels (239 vs. 216 pmol/8 × 108 erythrocytes; P = N.S.) and led to resolution of 6‐MMP associated side effects (elevated transaminases, leucopenia and flu‐like symptoms) in all but two patients. After mean follow‐up of 36 months, 12 patients remained in clinical remission on split‐dose mercaptopurine. Five of the remaining eight patients escalated to anti‐TNF therapy, two progressed to surgery, and one switched to tioguanine therapy.

Conclusion

Split‐dose administration of mercaptopurine/AZA represents an alternative option in IBD patients with preferential 6‐MMP metabolism who might otherwise require steroid exposure or escalation of therapy.