bluuebunny/crossref_metadata_2025 huggingface dataset:
Monte Carlo simulations of electron thermalization in alkali iodide and alkaline-earth fluoride scintillators
Authors: Wang Zhiguo , Xie YuLong , Campbell Luke W. , Gao Fei , Kerisit Sebastien
Published: July 2012

A Monte Carlo model of electron thermalization in inorganic scintillators, which was developed and applied to CsI in a previous publication [Wang et al., J. Appl. Phys. 110, 064903 (2011)], is extended to another material of the alkali halide class, NaI, and to two materials from the alkaline-earth halide class, CaF2 and BaF2. This model includes electron scattering with both longitudinal optical (LO) and acoustic phonons as well as the effects of internal electric fields. For the four pure materials, a significant fraction of the electrons recombine with self-trapped holes and the thermalization distance distributions of the electrons that do not recombine peak between approximately 25 and 50 nm and extend up to a few hundreds of nanometers. The thermalization time distributions of CaF2, BaF2, NaI, and CsI extend to approximately 0.5, 1, 2, and 7 ps, respectively. The simulations show that the LO phonon energy is a key factor that affects the electron thermalization process. Indeed, the higher the LO phonon energy is, the shorter the thermalization time and distance are. The thermalization time and distance distributions show no dependence on the incident γ-ray energy. The four materials also show different extents of electron-hole pair recombination due mostly to differences in their electron mean free paths (MFPs), LO phonon energies, initial densities of electron-hole pairs, and static dielectric constants. The effect of thallium doping is also investigated for CsI and NaI as these materials are often doped with activators. Comparison between CsI and NaI shows that both the larger size of Cs+ relative to Na+, i.e., the greater atomic density of NaI, and the longer electron mean free path in NaI compared to CsI contribute to an increased probability for electron trapping at Tl sites in NaI versus CsI.
Sub-bandgap photocurrent effects on dynamic pyroelectric measurement in Pt/PbTiO3/Nb:SrTiO3 heterostructures
Authors: Takahashi R. , Tybell T. , Lippmaa M.
Published: July 2012

We have studied how sub-bandgap photocurrents affect dynamic pyroelectric measurements in ferroelectric Pt/PbTiO3/Nb:SrTiO3 heterostructures. Currents generated in the PbTiO3 capacitors under pulsed laser illumination were found to be a combination of pyroelectric and photoelectric signals. We show that time-domain measurements can be used to separate the two contributions and obtain accurate pyroelectric hysteresis loops. Photocurrents, also present for excitation laser photon energies below the bandgap of the PbTiO3 ferroelectric, were assigned to charge carriers generated at the electrode interfaces. Hysteresis loops were observed for both current components, indicating that photocarrier extraction from the ferroelectric heterostructure can be controlled by choosing a suitable domain polarity.
Strain dependent polarization and dielectric properties of epitaxial BaTiO3 from first-principles
Authors: Ong P. V. , Lee Jaichan
Published: July 2012

Using first-principles calculations, we investigated the strain dependences of the polarization and dielectric properties of epitaxial BaTiO3 crystals over a wide range of misfit strains. We predict stabilization of the monoclinic r-phase over a wide range of strained states in the epitaxial BaTiO3. The lowest energy [111] phonons in the r-phase become softened as the misfit strain approaches the transition boundaries towards the c- and aa-phases, but incomplete at the boundaries, in contrast to strained SrTiO3. The strain dependence of the dielectric constant shows broadened peaks and considerable deviation from the Curie-Weiss-type law near critical strains, which are attributed to the incomplete phonon softening.
Phonon thermal conductivity of GaN nanotubes
Authors: Zhou Gang , Li Liangliang
Published: July 2012

We theoretically investigated the phonon thermal conductivity of gallium nitride (GaN) nanotubes with diameters ranging from a few nanometers to 120 nanometers using the Boltzmann transport equation and took into account the phonon dispersion relations of the nanotubes and the influence of boundary scattering on the non-equilibrium phonon distribution. The calculation results show that the phonon thermal conductivity of GaN nanotubes is much lower than that of the bulk counterpart and it depends on the thickness, inner and outer diameters, and surface roughness of the nanotubes. A small thickness or a large surface roughness leads to a small thermal conductivity. The reduction of the phonon thermal conductivity of the nanotubes is mainly due to the decrease of the phonon group velocity, change of the phonon relaxation rate, and enhancement of phonon boundary scattering. The understanding and results on the thermal conductivity obtained in this work are important for the optoelectronic devices based on GaN nanotubes and nanowires, and the developed calculation method on the phonon thermal conductivity is generally applicable and can be used for other nanotube systems.
Minimal energy control of a nanoelectromechanical memory element
Authors: Khovanova N. A. , Windelen J.
Published: July 2012

The Pontryagin minimal energy control approach has been applied to minimise the switching energy in a nanoelectromechanical memory system and to characterise global stability of the oscillatory states of the bistable memory element. A comparison of two previously experimentally determined pulse-type control signals with Pontryagin control function has been performed, and the superiority of the Pontryagin approach with regard to power consumption has been demonstrated. An analysis of global stability shows how values of minimal energy can be utilized in order to specify equally stable states.
Acceleration of electrons to high energies in a standing wave generated by counterpropagating intense laser pulses with tilted amplitude fronts
Authors: Galkin A. L. , Korobkin V. V. , Romanovskiy M. Yu. , Trofimov V. A. , Shiryaev O. B.
Published: July 2012

The dynamics of an electron in a standing wave generated by two relativistically intense linearly polarized laser pulses with tilted amplitude fronts is studied. The analysis is based on solving numerically the relativistic Newton’s equation with the corresponding Lorentz force. A new scheme of laser acceleration of electrons by the direct action of the standing wave is proposed. It is shown that short bunches of electrons with energies reaching several GeV can be created for relativistic laser intensities.
Focused high frequency needle transducer for ultrasonic imaging and trapping
Authors: Hsu Hsiu-Sheng , Zheng Fan , Li Ying , Lee Changyang , Zhou Qifa , Kirk Shung K.
Published: July 2012

A miniature focused needle transducer (<1 mm) was fabricated using the press-focusing technique. The measured pulse-echo waveform showed the transducer had center frequency of 57.5 MHz with 54% bandwidth and 14 dB insertion loss. To evaluate the performance of this type of transducer, invitro ultrasonic biomicroscopy imaging on the rabbit eye was obtained. Moreover, a single beam acoustic trapping experiment was performed using this transducer. Trapping of targeted particle size smaller than the ultrasonic wavelength was observed. Potential applications of these devices include minimally invasive measurements of retinal blood flow and single beam acoustic trapping of microparticles.
Debye shielding in a dusty plasma with nonextensively distributed electrons and ions
Authors: Liu Y. , Liu S. Q. , Xu K.
Published: July 2012

The phenomenon of Debye shielding in dusty plasmas is investigated within the framework of nonextensively distributed electrons and ions. The effects of dust grain charge fluctuation are considered. It shows that the increase of the nonextensive parameters of electrons and ions will lead to the decrease of the shielding distance and it is due to that the effective temperature of nonextensively distributed particles drops with the increase of nonextensive parameters. There is a rather interesting result that the Debye shielding effects may vanish in a certain condition when the fluctuation of the dust grain charges is taken into account.
Generation of magnetized collisionless shocks by a novel, laser-driven magnetic piston
Authors: Schaeffer D. B. , Everson E. T. , Winske D. , Constantin C. G. , Bondarenko A. S. , Morton L. A. , Flippo K. A. , Montgomery D. S. , Gaillard S. A. , Niemann C.
Published: July 2012

We present experiments on the Trident laser facility at Los Alamos National Laboratory which demonstrate key elements in the production of laser-driven, magnetized, laboratory-scaled astrophysical collisionless shocks. These include the creation of a novel magnetic piston to couple laser energy to a background plasma and the generation of a collisionless shock precursor. We also observe evidence of decoupling between a laser-driven fast ion population and a background plasma, in contrast to the coupling of laser-ablated slow ions with background ions through the magnetic piston. 2D hybrid simulations further support these developments and show the coupling of the slow to ambient ions, the formation of a magnetic and density compression pulses consistent with a collisionless shock, and the decoupling of the fast ions.
Recovery of epididymal spermatozoa from bull and red deer, stored at different times and temperatures before freezing - thawing
Authors: Malcotti V. , Pelufo V. , Bergamo N. , Aisen E.
Published: July 2012

In order to preserve male germoplasm, the recovery and cryopreservation of spermatozoa from the epididymides of hunted animals represents an accessible source of gametes. As a first experimental model, epididymal spermatozoa from slaughtered bulls were recovered at 30, 54, 78 and 102 h after death. The scrotal contents were stored at either 5 or 20°C. The sperm cells of each treatment (time + temperature combinations) were frozen with Triladyl (T) or Triladyl + Trehalose (TT) diluents. In order to assess sperm viability and integrity, post-thawing evaluation included individual motility, supravital stain, hyperosmotic swelling test (E+), acrosome status and sperm chromatin structure assay. Both at raw and post-refrigerated states, the sperm motility rate was higher in sperm obtained from epidydmes stored at 5°C, compared with those stored at 20°C for all collection times. Sperm collected at 102 h after death from epididymides stored at 5°C maintained a motility of 20% (120 h, raw state). When comparisons were carried out after thawing, motility was higher in the 5°C group, achieving the best results with TT diluent (7.5%) at 102 h. However, when supravital stain and E+ tests were observed, viability and membrane integrity were well preserved even at 102 h post mortem (30 and 36%, respectively, with TT diluent at 5°C). These results suggest that frozen-thawed epididymal spermatozoa could have a low motility rate while most of them remain alive. Acrosome status was not greatly affected by storage time.
In a second experiment, epididymal spermatozoa from hunted red deer stags (Cervus elaphus) were recovered at 4 and 30 h after death. The scrotal contents were stored at 20°C, because that temperature is closer to field and shipment conditions. The sperm cells were frozen with TT diluent. Post-thawing evaluation included the same parameters indicated for bull spermatozoa. The assessment of spermatozoa collected at 30 hours post mortem and then subsequently frozen and thawed indicated that at this time an acceptable motility rate (35%) and viability (39.7%) were achieved. Frozen and subsequently thawed epididymal spermatozoa showed 47.9% of membrane integrity, 59.3% of acrosome integrity and 26.5% of chromatin damage, using TT diluent. A preliminary in vivo trial demonstrated that the pregnancy rate in artificially inseminated deer decreased when sperm were obtained at 30 h post mortem. According to these results, it may be concluded that storage at 5°C is better than 20°C to obtain well preserved epididymal spermatozoa from bulls, and that TT could be a useful cryoprotectant to preserve viable and fertile sperm cells after the freezing–thawing process. Before these results can be applied to assisted reproduction programs in endangered deer species, some adaptations must be developed.
Factors affecting the number of STRO-1+ stem cells derived from regenerating antler and pedicle cells of red and fallow deer
Authors: Kužmová Erika , Kotrba Radim , Rolf Hans J. , Bartoš Luděk , Wiese K. Günter , Schulz Jutta , Bubenik George A.
Published: July 2012

Mesenchymal stem cells positive to surface antigen STRO-1 were isolated from regenerating antlers of red deer (Cervus elaphus) and fallow deer (Dama dama) using a magnetic-activated cell sorting (MACS) method. In this study we analysed factors potentially affecting the number of STRO-1+ cells in the cell cultures. With regard to the STRO-1 antigen, we evaluated data from 188 MACS separation procedures of cell cultures cultivated in Dulbecco’s Modified Eagle Medium and 10% fetal calf serum of four fallow deer males (130 procedures) and four red deer males (58 procedures). The analysed factors were the sampling site of the antler or the pedicle, cell passage and type of the cell culture (mixed or STRO-1 negative cell cultures). The percentage of obtained STRO-1+ cells varied greatly from 0.4 to 38.9% for fallow deer and from 1.8 to 16.5% for red deer. We have not found any significant influence of the sampling site. The passage and the type of culture were significant factors for both fallow and red deer cells. The highest numbers of STRO-1+ cells were obtained from the second passage from both fallow and red deer cell cultures (24.6 and 5.5%, respectively). Our experiment revealed that we can maximise the number of STRO-1+ cells in the cultures by manipulating the cultivation factors.
Assessing red deer antler density with a hydrostatic method versus a new parametric volume-modelling technique using 3D-CAD
Authors: Paramio M. A. R. , Muñoz-Cobo J. , Moro J. , Gutierrez R. , Oya A. , Tellado S. , Azorit C.
Published: July 2012

Two methods of volume measurement were compared, to develop a simple and reliable method for estimating the whole-antler density. We used 10 cast antlers, previously dried and weighed, from 10 different red deer (Cervus elaphus hispanicus) individuals. The volumes were determined by the traditional Archimedes method versus a new parametric volume-modelling technique using a ‘computer-aided design-three dimensions’ (3D-CAD), which is now being used in the biomedical industry in applications such as medical-implant design, tissue engineering and in developing a better understanding of anatomical functionality and morphological analysis. The process paths to follow in the generation of CAD models from cast antlers were described. The whole-antler density was estimated from the weight and volume measurement and a paired-sample comparison procedure was performed to assess differences between volumes as well as densities. Cast-antler weight ranged from 219.93 to 1857.9 g, and the volume estimated by the hydrostatic method was 732.45 ± 474.06 cm3 and by the CAD-3D method it was 730.65 ± 492.59 cm3. The DM density of the antler by the hydrostatic method (Density A) was 1.112 ± 0.120 g/cm3, ranging from 0.915 to 1.345 g/cm3 (Shapiro–Wilks, P = 0.449), and by the 3D-CAD method (Density B) it was 1.112 ± 0.158 g/cm3, ranging from 0.939 to 1.326 g/cm3 (Shapiro–Wilks, P = 0.751). There were no differences in the volume (t = 0.95, P = 0.37) or density (t = 0.54, P = 0.60) between the two methods and the correlation coefficient between Density A and Density B was 0.968. Both methods had similar reliability, although the computing process with the 3D-CAD system calculated antler volume faster than did the traditional hydrostatic weighing. 3D-CAD also avoided cast damage and the methodological problems with larger or smaller antlers or with floatability due to low density, which occur when using the hydrostatic method.
Regulation of aminopeptidases by the renin - angiotensin system: monitoring seasonal variations in red deer and fallow deer from a Mediterranean ecosystem
Authors: Galán-Ocaña A. , Ramírez-Expósito M. J. , Martínez-Martos J. M. , Tellado S. , Azorit C.
Published: July 2012

The circulating renin–angiotensin system (RAS) is well known for its systemic role in the regulation of blood pressure, renal hemodynamics and fluid homeostasis. However, in mammals several organs also contain a local RAS, including male and female reproductive tissues. In the present study we analysed serum from a free-living population of red deer (Cervus elaphus hispanicus) and fallow deer (Dama dama) to determine the activity of four RAS-regulating aminopeptidases (aminopeptidase A, aspartyl aminopeptidase, aminopeptidase N and aminopeptidase B) as part of a study of annual cycles of growth and condition. Our aim was to detect seasonal variations in the activities of these aminopeptidases and their relationship to the reproductive behaviour of both species in a Mediterranean environment. In both males and females there was a maximum peak of activity in autumn. A second peak was detected in spring for males while in females activity was also higher in summer. These changes may be related to a different endocrine status according to their seasonal cycle, the decreased photoperiod in autumn and the normal timing of the seasonal growth cycle. Thus, changes in the activity of RAS-regulating aminopeptidases could reflect the functional role of angiotensins through the annual cycle of both species, also suggesting an important role of these peptide hormones in the regulation of these biological processes.
Platinum-Ruthenium Nanoparticles: Active and Selective Catalysts for Hydrogenation of Phenylacetylene
Authors: Ruzicka Jan-Yves , Anderson David P. , Gaw Sally , Golovko Vladimir B.
Published: July 2012

Bimetallic metal nanoparticles are often more catalytically active than their monometallic counterparts, due to a so-called ‘synergistic effect’. Atomically precise ruthenium-platinum clusters have been shown to be active in the hydrogenation of phenylacetylene to styrene (a reaction of importance to the polymer industry). However, the synthesis of these clusters is generally complex, and cannot be modified to produce clusters with differing metal compositions or ratios. Hence, any truly systematic study of compositional effects using such clusters is hindered by the inaccessibility of certain metal ratios. In this study, a series of larger bimetallic ruthenium-platinum colloids of varying metal ratios was synthesised in solution and immobilised on silica. Catalytic activity was evaluated by hydrogenation of phenylacetylene to styrene. Both bimetallic and monometallic colloids were active catalysts for the hydrogenation of phenylacetylene to styrene and further to ethylbenzene. Of those studied, a catalyst composed of 73 % platinum-27 % ruthenium (by moles) showed the highest activity. This suggests that synergistic effects play an important role in the catalysis of this reaction. To our knowledge this is the first systematic study of ruthenium-platinum nanoparticle catalytic activity on this reaction.
Parental diet-induced obesity leads to retarded early mouse embryo development and altered carbohydrate utilisation by the blastocyst
Authors: Binder Natalie K. , Mitchell Megan , Gardner David K.
Published: July 2012

Maternal obesity results in reproductive complications, whereas the impact of paternal obesity is unclear. In the present study, the effects of parental obesity on preimplantation embryo cell cycle length and carbohydrate utilisation were investigated. Maternal and paternal obesity were assessed independently by deriving zygotes from normal or obese C57BL/6 female mice mated with normal Swiss male mice (maternal obesity), or from normal Swiss female mice mated with normal or obese C57BL/6 male mice (paternal obesity). Zygotes were cultured in vitro and development was then assessed by time-lapse microscopy and metabolism determined using ultramicrofluorescence. Maternal obesity was associated with a significant delay in precompaction cell cycle kinetics from the 1-cell stage. A significant increase in glucose consumption by embryos from obese compared with normal females occurred after compaction, although glycolysis remained unchanged. Similarly, paternal obesity led to significant delays in cell cycle progression during preimplantation embryo development. However, this developmental delay was observed from the second cleavage stage onwards, following embryonic genome activation. Blastocysts from obese males showed disproportionate changes in carbohydrate metabolism, with significantly increased glycolysis. Overall, metabolic changes were not inhibitory to blastocyst formation; however, blastocyst cell numbers were significantly lower when either parent was obese. These data suggest that both maternal and paternal obesity significantly impacts preimplantation embryo physiology.
Unobserved time effects confound the identification of climate change impacts
Authors: Auffhammer Maximilian , Vincent Jeffrey R.
Published: July 2012

A recent study by Feng et al. [Feng S, Krueger A, Oppenheimer M (2010)
Proc Natl Acad Sci USA
107:14257–14262] in PNAS reported statistical evidence of a weather-driven causal effect of crop yields on human migration from Mexico to the United States. We show that this conclusion is based on a different statistical model than the one stated in the paper. When we correct for this mistake, there is no evidence of a causal link.
A phenomenological explanation for the anomalous ion heating observed in the JET alpha-heating experiment of 1997
Authors: Testa D. , Albergante M.
Published: July 2012

In the so-called ‘alpha-heating’ experiment performed on the JET tokamak during the deuterium–tritium campaign of 1997, the ion temperature was found to be far exceeding (both in absolute value and in its rise time) the level that could have been expected from direct collisional heating by the fusion-born alpha particles themselves and energy equipartition with the electrons. To date, no explanation has been put forward for this long standing puzzle, despite much work having been performed on this subject in the early 2000s.

Two analysis methods that have recently become available have been employed to re-analyse these observations of an anomalous ion heating. First, an algorithm based on the sparse representation of signals has been used to analyse magnetic, reflectometry and electron-cyclotron emission measurements of the turbulence spectra in the drift-wave range of frequencies. This analysis has then been complemented with turbulence simulations performed with the GENE code.

We find, both experimentally and in the simulations, that the presence of a minority, but sufficiently large, population of fusion-born alpha particles that have not yet fully thermalized stabilizes the turbulence in the ion-drift direction, but practically does not affect the turbulence in the electron-drift direction. We link such stabilization of the ion-drift-wave turbulence to the increase in the ion temperature above the level achieved in similar discharges that did not have (at all or enough) alpha particles. When the fusion-born alpha particles have fully thermalized, the turbulence spectrum in the ion-drift direction reappears at somewhat larger amplitudes, which we link to the ensuing reduction in the ion temperature. This phenomenological dynamics fully corresponds to the actual experimental observations. By taking into account an effect of the alpha particles that had not been previously considered, our new analysis finally presents a phenomenological explanation for the so-far-unexplained anomalous ion heating observed in the JET alpha-heating experiment of 1997.

Through the formulation of an empirical criterion for ion-drift-wave turbulence stabilization by fusion-born alpha particles, we also show why similar observations were not made in the other deuterium–tritium experiments run so far in JET and TFTR. This allows assessing the operational domain for this stabilization mechanism for ion-drift-wave turbulence in future burning plasma experiments such as ITER, which may open a new path towards the sustainment of a high energy gain in such forthcoming devices.
Gemma: a resource for the reuse, sharing and meta-analysis of expression profiling data
Authors: Zoubarev Anton , Hamer Kelsey M. , Keshav Kiran D. , McCarthy E. Luke , Santos Joseph Roy C. , Van Rossum Thea , McDonald Cameron , Hall Adam , Wan Xiang , Lim Raymond , Gillis Jesse , Pavlidis Paul
Published: July 2012

Summary: Gemma is a database, analysis software system and web site for genomics data re-use and meta-analysis. Currently, Gemma contains analyzed data from over 3300 expression profiling studies, yielding hundreds of millions of differential expression results and coexpression patterns (correlated expression) for retrieval and visualization. With optional registration users can save their own data and securely share it with other users. Web services and integration with third-party resources further increase the scope of the tools, which include a Cytoscape plugin.

Availability:  http://chibi.ubc.ca/Gemma, Apache 2.0 license.

Contact:  paul@chibi.ubc.ca
Prognostic importance of exercise brain natriuretic peptide in asymptomatic degenerative mitral regurgitation
Authors: Magne Julien , Mahjoub Haifa , Pibarot Philippe , Pirlet Charles , Pierard Luc A. , Lancellotti Patrizio
Published: July 2012

Aim

The exercise Doppler echocardiographic stress test can be of interest in the management of asymptomatic patients with primary mitral regurgitation (MR). The resting brain natriuretic peptide (BNP) level is a good surrogate marker of the consequences of MR and is a powerful predictor of outcome. The incremental prognostic value of BNP response during exercise is unknown. We aimed to identify the determinants of exercise BNP level and to evaluate its prognostic value in asymptomatic patients with primary MR.

Methods and results

Comprehensive resting and exercise transthoracic Doppler echocardiography was performed in 113 consecutive asymptomatic patients with moderate to severe degenerative MR and preserved left ventricular (LV) function. Blood samples were collected both at rest and during exercise. The BNP level significantly increased from rest to exercise (P < 0.0001). The independent determinants of exercise BNP were resting E/Ea ratio (P = 0.043), indexed left atrial volume (P = 0.022), and exercise LV global longitudinal strain (P = 0.001). There was a significant graded relationship between increasing BNP level at exercise (according to tertiles) and increased incidence of cardiac events (death, heart failure, mitral valve surgery driven by symptoms, or LV dilatation/dysfunction onset) (1 year, 11 ± 5% vs. 14 ± 6% vs. 43.5 ± 9%; 2 years, 21 ± 7% vs. 40 ± 8% vs. 67 ± 9%; in tertiles 1, 2 and 3, respectively). On multivariable analysis, after adjustment for demographic and echocardiographic data and for resting BNP level, exercise BNP remained significantly associated with increased risk of cardiac events during the follow‐up (hazard ratio 2.8 and 3.4, P = 0.041 and 0.023, for tertiles 2 and 3, as compared with tertile 1).

Conclusions

In asymptomatic patients with primary MR, exercise BNP level provides incremental prognostic value beyond what is achieved by demographic and echocardiographic data and resting BNP level. Patients with elevated exercise BNP should be considered at high risk of reduced cardiac event‐free survival.
A Unified Effort to Fight an Enemy of Wheat and Barley: Fusarium Head Blight
Authors: McMullen Marcia , Bergstrom Gary , De Wolf Erick , Dill-Macky Ruth , Hershman Don , Shaner Greg , Van Sanford Dave
Published: July 2012

Wheat and barley are critical food and feed crops around the world. Wheat is grown on more land area worldwide than any other crop. In the United States, production of wheat and barley contributes to domestic food and feed use, and contributes to the export market and balance of trade. Fifteen years ago, Plant Disease published a feature article titled “Scab of wheat and barley: A re-emerging disease of devastating impact”. That article described the series of severe Fusarium head blight (FHB) epidemics that occurred in the United States and Canada, primarily from 1991 through 1996, with emphasis on the unparalleled economic and sociological impacts caused by the 1993 FHB epidemic in spring grains in the Northern Great Plains region. Earlier publications had dealt with the scope and damage caused by this disease in the United States, Canada, Europe, and China. Reviews published after 1997 further described this disease and its impact on North American grain production in the 1990s. This article reviews the disease and documents the information on U.S. FHB epidemics since 1997. The primary goal of this article is to summarize a sustained, coordinated, and collaborative research program that was put in place shortly after the 1993 epidemic, a program intended to quickly lead to improved management strategies and outreach implementation. This program serves as a model to deal with other emerging plant disease threats.
First Report of the Cereal Cyst Nematode Heterodera filipjevi on Wheat in Serbia
Authors: Oro V. , Živković S. , Ivanović Ž. , Waeyenberge L.
Published: July 2012

The most globally recognized and economically important nematode on wheat is the cereal cyst nematode (CCN) complex (1). One of the most important species of this group is Heterodera filipjevi (Madžidov, 1981) Mulvey and Golden, 1983. During regular soil quarantine control in September 2010, Heterodera sp. cysts were found in soil samples originating from a wheat field in Gunaroš, Vojvodina Province, in northern Serbia. The wheat was a winter crop grown in a dryland production system and had an average cyst density of 2.50/100 cm3 of soil. Morphologically, the cysts were golden brown and lemon shaped with a posterior protuberance. The vulval cone was bifenestrate with horseshoe-shaped semifenestra, bullae, and underbridge. Cyst measurements (n = 30) ranged as follows: cyst length (without neck): 511.50 to 899.00 μm, cyst width: 201.50 to 682.00 μm, fenestral length: 44.80 to 65.60 μm, fenestral width: 24.00 to 40.00 μm, vulval bridge length: 12.80 to 20.80 μm, vulval bridge width: 6.40 to 14.40 μm, vulval slit: 6.00 to 12.80 μm, and underbridge length: 60.00 to 112.00 μm. The second-stage juveniles had an offset head, stylet with characteristic anchor-shaped basal knobs, four incisures, and a conical tail with a rounded tip. The J2 morphometrics (n = 30) were: length: 447.30 to 611.10 μm, width: 22.40 to 25.60 μm, stylet: 20.80 to 24.00 μm, tail length: 56.00 to 68.80 μm, tail width: 14.40 to 19.20 μm, and hyaline length: 35.20 to 44.80 μm. The ITS region was used for molecular analysis. Each DNA sample was extracted from a single cyst. Sequencing was done with primers TW81 and AB28 (2). In comparison with other H. filipjevi populations, the obtained sequence (GenBank Accession No. JX235959) revealed 99 to 100% similarity. Morphological and molecular data confirmed the existence of H. filipjevi. This is, to our knowledge, the first report of H. filipjevi from Serbia. Since wheat has important socioeconomic value for Serbia, after extensive surveys, additional phytosanitary measures may be necessary to prevent the spread of this parasite.

References: (1) J. M. Nicol et al. Current Nematode Threats to World Agriculture. Genomics and Molecular Genetics of Plant-Nematode Interactions, Springer, New York, 2011. (2) A. M. Skantar et al. J. Nematol. 39:133, 2007.
Physiological and Biochemical Aspects of the Resistance of Banana Plants to Fusarium Wilt Potentiated by Silicon
Authors: Fortunato Alessandro Antonio , Rodrigues Fabrício Ávila , do Nascimento Kelly Juliane Teles
Published: July 2012

Silicon amendments to soil have resulted in a decrease of diseases caused by several soilborne pathogens affecting a wide number of crops. This study evaluated the physiological and biochemical mechanisms that may have increased resistance of banana to Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense, after treatment with silicon (Si) amendment. Plants from the Grand Nain (resistant to F. oxysporum f. sp. cubense) and “Maçã” (susceptible to F. oxysporum f. sp. cubense) were grown in plastic pots amended with Si at 0 or 0.39 g/kg of soil (–Si or +Si, respectively) and inoculated with race 1 of F. oxysporum f. sp. cubense. Relative lesion length (RLL) and asymptomatic fungal colonization in tissue (AFCT) were evaluated at 40 days after inoculation. Root samples were collected at different times after inoculation with F. oxysporum f. sp. cubense to determine the level of lipid peroxidation, expressed as equivalents of malondialdehyde (MDA), hydrogen peroxide (H2O2), pigments (chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids), total soluble phenolics (TSP), and lignin-thioglycolic acid (LTGA) derivatives; the activities of the enzymes phenylalanine ammonia-lyases glucanases (PALs), peroxidases (POXs), polyphenoloxidases (PPOs), β-1,3-glucanases (GLUs), and chitinases (CHIs); and Si concentration in roots. Root Si concentration was significantly increased by 35.3% for the +Si treatment compared with the –Si treatment. For Grand Nain, the root Si concentration was significantly increased by 12.8% compared with “Maçã.” Plants from Grand Nain and “Maçã” in the +Si treatment showed significant reductions of 40.0 and 57.2%, respectively, for RLL compared with the –Si treatment. For the AFCT, there was a significant reduction of 18.5% in the +Si treatment compared with the –Si treatment. The concentration of MDA significantly decreased for plants from Grand Nain and “Maçã” supplied with Si compared with the –Si treatment while the concentrations of H2O2 on roots and pigments on leaves significantly increased. The concentrations of TSP and LTGA derivatives as well as the PALs, PPOs, POXs, GLUs, and CHIs activities significantly increased on roots of plants from Grand Nain and “Maçã” from the +Si treatment compared with the –Si treatment. Results of this study suggest that the symptoms of Fusarium wilt on roots of banana plants supplied with Si decreased due to an increase in the concentrations of H2O2, TSP, and LTGA derivatives and greater activities of PALs, PPOs, POXs, GLUs, and CHIs.
Effects of early visual experience on the background preference in juvenile cuttlefish
Sepia pharaonis
Authors: Lee Yi-Hsin , Yan Hong Young , Chiao Chuan-Chin
Published: July 2012

Although cuttlefish are capable of showing diverse camouflage body patterns against a variety of background substrates, whether they show background preference when given a choice of substrates is not well known. In this study, we characterized the background choice of post-embryonic cuttlefish (
Sepia pharaonis
) and examined the effects of rearing visual environments on their background preferences. Different rearing backgrounds (enriched, uniformly grey and checkerboard) were used to raise cuttlefish from eggs or hatchlings, and four sets of two-background-choice experiments (differences in contrast, shape, size and side) were conducted at day 1 and weeks 4, 8 and 12 post-hatch. Cuttlefish reared in the enriched environment preferred high-contrast backgrounds at all post-embryonic stages. In comparison, those reared in the impoverished environments (uniformly grey and checkerboard) had either reversed or delayed high-contrast background preference. In addition, cuttlefish raised on the uniformly grey background, exposed to a checkerboard briefly (0.5 or 3 h) at week 4 and tested at week 8 showed increased high-contrast background preference. Interestingly, cuttlefish in the enriched group preferred an object size similar to their body size at day 1 and week 4, but changed this preference to smaller objects at week 12. These results suggest that high-contrast backgrounds may be more adaptive for juvenile cuttlefish, and visually enriched environments are important for the development of these background preference behaviours.
Phenotypic plasticity and adaptive evolution contribute to advancing flowering phenology in response to climate change
Authors: Anderson Jill T. , Inouye David W. , McKinney Amy M. , Colautti Robert I. , Mitchell-Olds Tom
Published: July 2012

Anthropogenic climate change has already altered the timing of major life-history transitions, such as the initiation of reproduction. Both phenotypic plasticity and adaptive evolution can underlie rapid phenological shifts in response to climate change, but their relative contributions are poorly understood. Here, we combine a continuous 38 year field survey with quantitative genetic field experiments to assess adaptation in the context of climate change. We focused onBoechera stricta(Brassicaeae), a mustard native to the US Rocky Mountains. Flowering phenology advanced significantly from 1973 to 2011, and was strongly associated with warmer temperatures and earlier snowmelt dates. Strong directional selection favoured earlier flowering in contemporary environments (2010–2011). Climate change could drive this directional selection, and promote even earlier flowering as temperatures continue to increase. Our quantitative genetic analyses predict a response to selection of 0.2 to 0.5 days acceleration in flowering per generation, which could account for more than 20 per cent of the phenological change observed in the long-term dataset. However, the strength of directional selection and the predicted evolutionary response are likely much greater now than even 30 years ago because of rapidly changing climatic conditions. We predict that adaptation will likely be necessary for long-termin situpersistence in the context of climate change.
Negative feedback from maternal signals reduces false alarms by collectively signalling offspring
Authors: Hamel Jennifer A. , Cocroft Reginald B.
Published: July 2012

Within animal groups, individuals can learn of a predator's approach by attending to the behaviour of others. This use of social information increases an individual's perceptual range, but can also lead to the propagation of false alarms. Error copying is especially likely in species that signal collectively, because the coordination required for collective displays relies heavily on social information. Recent evidence suggests that collective behaviour in animals is, in part, regulated by negative feedback. Negative feedback may reduce false alarms by collectively signalling animals, but this possibility has not yet been tested. We tested the hypothesis that negative feedback increases the accuracy of collective signalling by reducing the production of false alarms. In the treehopperUmbonia crassicornis, clustered offspring produce collective signals during predator attacks, advertising the predator's location to the defending mother. Mothers signal after evicting the predator, and we show that this maternal communication reduces false alarms by offspring. We suggest that maternal signals elevate offspring signalling thresholds. This is, to our knowledge, the first study to show that negative feedback can reduce false alarms by collectively behaving groups.
The Lateral Organ Boundaries Domain Transcription Factor LBD20 Functions in Fusarium Wilt Susceptibility and Jasmonate Signaling in Arabidopsis
Authors: Thatcher Louise F. , Powell Jonathan J. , Aitken Elizabeth A.B. , Kazan Kemal , Manners John M.
Published: July 2012

The LATERAL ORGAN BOUNDARIES (LOB) DOMAIN (LBD) gene family encodes plant-specific transcriptional regulators functioning in organ development. In a screen of Arabidopsis (Arabidopsis thaliana) sequence-indexed transferred DNA insertion mutants, we found disruption of the LOB DOMAIN-CONTAINING PROTEIN20 (LBD20) gene led to increased resistance to the root-infecting vascular wilt pathogen Fusarium oxysporum. In wild-type plants, LBD20 transcripts were barely detectable in leaves but abundant in roots, where they were further induced after F. oxysporum inoculation or methyl jasmonate treatment. Induction of LBD20 expression in roots was abolished in coronatine insensitive1 (coi1) and myc2 (allelic to jasmonate insensitive1) mutants, suggesting LBD20 may function in jasmonate (JA) signaling. Consistent with this, expression of the JA-regulated THIONIN2.1 (Thi2.1) and VEGETATIVE STORAGE PROTEIN2 (VSP2) genes were up-regulated in shoots of lbd20 following treatment of roots with F. oxysporum or methyl jasmonate. However, PLANT DEFENSIN1.2 expression was unaltered, indicating a repressor role for LBD20 in a branch of the JA-signaling pathway. Plants overexpressing LBD20 (LBD20-OX) had reduced Thi2.1 and VSP2 expression. There was a significant correlation between increased LBD20 expression in the LBD20-OX lines with both Thi2.1 and VSP2 repression, and reduced survival following F. oxysporum infection. Chlorosis resulting from application of F. oxysporum culture filtrate was also reduced in lbd20 leaves relative to the wild type. Taken together, LBD20 is a F. oxysporum susceptibility gene that appears to regulate components of JA signaling downstream of COI1 and MYC2 that are required for full elicitation of F. oxysporum- and JA-dependent responses. To our knowledge, this is the first demonstration of a role for a LBD gene family member in either biotic stress or JA signaling.
The role of canopy gaps in the regeneration of coastal dune forest
Authors: Grainger Matthew J. , van Aarde Rudi J.
Published: July 2012

In regenerating coastal dune forest, the canopy consists almost exclusively of a single species, Acacia karroo. When these trees die, they create large canopy gaps. If this promotes the persistence of pioneer species to the detriment of other forest species, then the end goal of a restored coastal dune forest may be unobtainable. We wished to ascertain whether tree species composition and richness differed significantly between canopy gaps and intact canopy, and across a gradient of gap sizes. In three known‐age regenerating coastal dune forest sites, we measured 146 gaps, the species responsible for gap creation, the species most likely to reach the canopy and the composition of adults, seedlings and saplings. We paired each gap with an adjacent plot of the same area that was entirely under intact canopy and sampled in the same way.

Most species (15 of 23) had higher abundance in canopy gaps. The probability of self‐replacement was low for A. karroo even in the largest gaps. Despite this predominance of shade‐intolerant species, regenerating dune forest appears to be in the first phase of succession with ‘forest pioneers’ replacing the dominant canopy species. The nature of these species should lead to successful regeneration of dune forest.
Outcome of multimodal therapy in operated acromegalic patients, a study in 115 patients
Authors: Albarel Frédérique , Castinetti Frédéric , Morange Isabelle , Conte‐Devolx Bernard , Gaudart Jean , Dufour Henry , Brue Thierry
Published: July 2012

Introduction

Given the new therapeutic options in acromegaly, it seemed important to evaluate the outcome of operated acromegalic patients today.

Objective

To analyse the characteristics and short‐ and long‐term surgical outcome of patients who underwent transsphenoidal surgery for a growth hormone (GH)‐secreting adenoma in our centre and to determine predictive factors of remission.

Design and patients

This retrospective 10‐year study included 115 newly diagnosed acromegalic patients operated on at Timone University Hospital, Marseille, France, between 1997 and 2007.

Measurements

Initial and long‐term outcomes were evaluated using stringent and current remission criteria, associating GH nadir after oral glucose tolerance test <0·4 μg/l and normal insulin‐like growth factor‐1 (IGF‐1) at 3 months, and a normal IGF‐1 at the end of follow‐up (52·4 ± 36·8 months, median 41 months, range 6·7–135·4 months, n = 99).

Results

At the end of follow‐up, 90·9% of patients had controlled disease. Overall, 49·5% of patients were in long‐term remission after surgery alone, and only 2·0% of patients experienced recurrent disease. Multivariate predictors of 3‐month remission included mean GH at diagnosis (P = 0·033), tumour invasion (P = 0·013) and surgeon report of incomplete or uncertain macroscopic resection (P = 0·003 and P = 0·047, respectively). Multivariate predictors at diagnosis of long‐term remission included mean GH level (P = 0·048), adenoma size (P = 0·007) and absence of pituitary deficit (P = 0·026).

Conclusions

In long‐term follow‐up after surgery of acromegaly, half of the patients achieved remission after surgery alone and more than 90% had their disease controlled. With stringent 3‐month remission criteria, recurrence was rare.
A species‐level model for metabolic scaling of treesII. Testing in a ring‐ and diffuse‐porous species
Authors: von Allmen Erica I. , Sperry John S. , Smith Duncan D. , Savage Van M. , Enquist Brian J. , Reich Peter B. , Bentley Lisa P.
Published: July 2012

A 17‐parameter ‘species model’ that predicts metabolic scaling from vascular architecture was tested in a diffuse‐porous maple (Acer grandidentatum) and a ring‐porous oak (Quercus gambelii). Predictions of midday water transport (Q) and its scaling with above‐ground mass (M) were compared with empirical measurements. We also tested the assumption thatQwas proportional to the biomass growth rate of the shoot (G).

Water transport and biomass growth rate were measured on 18 trees per species that spanned a broad range in trunk diameter (4–26 cm). Where possible, the same trees were used for obtaining the 17 model parameters that concern external branching, internal xylem conduit anatomy, and soil‐to‐canopy sap pressure drop.

The model succeeded in predicting theQbyMbscaling exponent,b, being within 8% (maple) and 6% (oak) of measured exponents from sap flow data. In terms of absoluteQ, the model was better in maple (16%Qoverestimate) than oak (128% overestimate). The overestimation ofQwas consistent with the model not accounting for cavitation, which is reportedly more prevalent in oak than in maple at the study site.

The modelled and measuredQbyMbexponents averaged within 3·6% of the measuredGbyMbexponents, supporting the assumption thatG ∝ Q1. The averagebexponent was 0·62 ± 0·016 (mean ± SE) across species, rejectingb = 0·75 for intraspecific scaling.

The performance of this species model, both for scaling purposes as well as for predicting rates of water consumption within and between species, argues for its further refinement and wider application in ecology and ecosystem biology.
Weight gains, blood parameters and faecal egg counts when meat‐goat kids were finished on alfalfa, red clover and orchardgrass pastures
Authors: Turner K. E. , Cassida K. A. , Zajac A. M.
Published: July 2012

The experiment was conducted in 2005–2007 to evaluate weight performance, blood parameters associated with forage nutrient‐use and anaemia from gastrointestinal nematode (GIN) infection, and faecal egg count (FEC) patterns of meat‐goat kids finished on alfalfa (Medicago sativa L.; ALF); red clover/grass mixture (Trifolium pratense L.; RCG); and orchardgrass (Dactylis glomerata L; OGR) pastures. Forage mass, crude protein (CP) and total digestible nutrients (TDN) displayed complex interactions between treatment and time (P < 0·001) across the grazing seasons. Final body weight was greater for goats finished on ALF and RCG than on OGR, except in 2006 when ALF was greater than RCG or OGR. The TDN/CP ratios in forages and blood urea nitrogen concentrations in grazing goats were highly correlated (r = 0·99; P = 0·02) and suggested that animals were wasting forage protein. Faecal egg count was variable over the grazing season each year (date and treatment × date interaction; P < 0·001), but in general, FEC indicated that goat kids grazing ALF were less affected by GIN than kids grazing RCG or OGR. Research is needed to determine whether strategic energy supplementation would improve protein‐use efficiency and resilience to parasite infection when finishing meat goats on pastures managed for high forage nutritive value.