bluuebunny/crossref_metadata_2025 huggingface dataset:
Postseismic motion after the 2001 MW 7.8 Kokoxili earthquake in Tibet observed by InSAR time series
Authors: Wen Yangmao , Li Zhenhong , Xu Caijun , Ryder Isabelle , Bürgmann Roland
Published: June 2012

On November 14th 2001, a Mw 7.8 earthquake occurred in the Kokoxili region of northern Tibet. The earthquake ruptured more than 400 km along the western part of the Kunlun fault with a maximum of 8 m left‐lateral slip. In this paper, we use a multitemporal Interferometric SAR (InSAR) time series technique to map the postseismic motion following the large Kokoxili event. SAR data from Envisat descending orbits along five adjacent tracks covering almost the entire ruptured fault length are used to calculate the displacement time series for a period between 2 and 6 years after the earthquake. A peak‐to‐trough signal of 8 cm in the radar line of sight is observed during the period between 2003 and 2008. Two different mechanisms are employed to explain the observed surface displacements, namely afterslip and viscoelastic relaxation. The observations inverted for afterslip on and below the coseismic rupture plane shows that the maximum slip in the afterslip model is 0.6 m. The position of the maximum postseismic slip is located in the middle of two relatively high coseismic slip patches, which suggests that afterslip is a plausible mechanism. Models of viscoelastic stress relaxation in a Maxwell half‐space give a best fitting viscosity for the mid‐to‐lower crust of 2–5 × 1019 Pa s, and the principal postseismic relaxation process is due to viscous flow in the lower crust to upper mantle. However, the InSAR observations are incapable of distinguishing between localized (afterslip) and distributed (viscoelastic relaxation) deformation. And the lowest misfits are produced by mixed models of viscoelastic relaxation in the mantle below 70 km and afterslip in the crust. Modeling of viscoelastic relaxation in a Maxwell half‐space, and also a mixed mechanism model, enables us to place an effective viscosity of 2 × 1019 Pa s on the lower crust to mantle of northern Tibet.
Direct observations of microscale turbulence and thermohaline structure in the Kuroshio Front
Authors: Nagai Takeyoshi , Tandon Amit , Yamazaki Hidekatsu , Doubell Mark J. , Gallager Scott
Published: June 2012

Direct observations of microstructure near the Kuroshio Front were conducted in August 2008 and October 2009. These show negative potential vorticity (PV) in the mixed layer south of the front, where directly measured turbulent kinetic energy dissipation rates are an order magnitude larger than predicted by wind‐scaling. These elevated dissipation rates scale better with an empirical scaling, which considers local wind and Ekman buoyancy flux driven by downfront wind. Near‐zero PV in the thermocline under the Kuroshio mainstream is observed at 200–300 m depth, with dissipation exceeding open ocean thermocline values by factors of 10–100. Overall, the large turbulent dissipation rates measured in the Kuroshio can be categorized into two groups, one characterized by low Richardson number along the Kuroshio Front thermocline, and the other characterized by high stratification away from the Kuroshio mainstream. The former is attributed to mixing by unbalanced frontal ageostrophic flows, and the latter is attributed to internal wave breaking. On average, both groups appear in regions of large horizontal density gradients. Observed thermohaline structure shows low salinity tongues from the surface to over 300 m depth and deep cold tongues, extending upward from 500 to 100 m depth in a narrow (20 km) zone, suggesting down and upwelling driven by geostrophic straining, which is confirmed by Quasigeostrophic‐Omega equation solutions. This implies that adiabatic along isopycnal subduction and diabatic diapycnal turbulent mixing acting in tandem at the Kuroshio Front likely contribute to NPIW formation.
Impact of glacial erosion on 10Be concentrations in fluvial sediments of the Marsyandi catchment, central Nepal
Authors: Godard V. , Burbank D. W. , Bourlès D. L. , Bookhagen B. , Braucher R. , Fisher G. B.
Published: June 2012

Several processes contribute to denudation in high‐mountain environments. Of these, glacial erosion is particularly difficult to constrain, despite its critical importance in the evolution of many mountain ranges. In this study, we present a new data set of10Be concentrations in fluvial sediments sampled along the Marsyandi River and its main tributaries in central Nepal. We interpret the 10Be concentrations as being significantly impacted by glacially derived sediments along the Marsyandi River. Such additions complicate conventional interpretations of 10Be‐derived catchment‐scale denudation rates. Using a simple linear mass‐conservation formulation, we invert our data set in order to separate the different denudational contributions to the observed signal, as well as to constrain their magnitude and spatial distribution. Our results suggest significant variations in glacial erosion, both in space and magnitude, within the Marsyandi catchment.
A centennial record of fluvial organic matter input from the discontinuous permafrost catchment of Lake Torneträsk
Authors: Vonk Jorien E. , Alling Vanja , Rahm Lars , Mörth Carl‐Magnus , Humborg Christoph , Gustafsson Örjan
Published: June 2012

High‐latitude regions are underlain by the most organic carbon (OC)‐rich soils on earth and currently subject to intense climate warming, potentially increasing remobilization and mineralization of soil OC. Sub‐Arctic Scandinavia is located on the 0°C mean annual isotherm and is therefore particularly vulnerable to climate change. This study aimed to establish a baseline for soil OC release over the past century into Lake Torneträsk, the largest lake in sub‐Arctic Scandinavia, through bulk geochemical and molecular radiocarbon analyses in chronologically constrained sediment cores. Our results suggest a dominance of peat‐derived terrestrial OC inflow. We show that the annual terrestrial OC inflow to the lake is ∼12 times higher than the in‐lake produced particulate OC, and consists for a large part (ca. 60%) of old OC from deep reservoirs in the catchment. The sedimentary record shows signs of increasing inflow of more degraded terrestrial matter since ∼1975, as indicated by increasing %TOC concentrations, a lowerδ13C value and lower TOC:TN ratios. Based on simultaneous changes in local climate and reported signs of permafrost degradation (e.g., active layer deepening, mire/peat erosion), the observed changes in the sedimentary record of Scandinavia's largest mountain lake likely reflect a climate warming‐induced change in terrestrial OC inflow.
Improving understanding of organic metal‐binding ligands in the ocean
Authors: Sander Sylvia , Buck Kristen N. , Lohan Maeve
Published: June 2012

Organic Ligands—A Key Control on Trace Metal Biogeochemistry in the Ocean; Salt Lake City, Utah, 25 February 2012
Equivalency of geologic and geodetic rates in contractional orogens: New insights from the Pamir Frontal Thrust
Authors: Li Tao , Chen Jie , Thompson Jessica A. , Burbank Douglas W. , Xiao Weipeng
Published: June 2012

Across contractional orogens, the equivalency between decadal convergence rates from geodetic GPS data and geologic shortening rates at time scales of thousands or millions of years has rarely been documented. Here, we present an example from the northern margin of Chinese Pamir, where the Main Pamir Thrust is tectonically quiescent, and recent deformation is concentrated on the Pamir Frontal Thrust (PFT). Based on dated and faulted fluvial terraces, magnetostratigraphy, and mapping, the horizontal shortening rate of the PFT is ∼6–7 mm/a at time scales of both ∼18.4 ka and ∼0.35 Ma, comparable to the geodetic rate of ∼6–9 mm/a across the same zone, implying that modern geodetic rates are a reasonable proxy for geologic rates since ∼0.35 Ma. Comparing this example with studies in other contractional orogens, we conjecture that a match or mismatch of geologic‐geodetic rates typically depends on the time scale of observation, fault geometry, and fault mechanics.
Interannual variability of carbon monoxide emission estimates over South America from 2006 to 2010
Authors: Hooghiemstra P. B. , Krol M. C. , van Leeuwen T. T. , van der Werf G. R. , Novelli P. C. , Deeter M. N. , Aben I. , Röckmann T.
Published: June 2012

We present the first inverse modeling study to estimate CO emissions constrained by both surface and satellite observations. Our 4D‐Var system assimilates National Oceanic and Atmospheric Administration Earth System Research Laboratory (NOAA/ESRL) Global Monitoring Division (GMD) surface and Measurements Of Pollution In The Troposphere (MOPITT) satellite observations jointly by fitting a bias correction scheme. This approach leads to the identification of a positive bias of maximum 5 ppb in MOPITT column‐averaged CO mixing ratios in the remote Southern Hemisphere (SH). The 4D‐Var system is used to estimate CO emissions over South America in the period 2006–2010 and to analyze the interannual variability (IAV) of these emissions. We infer robust, high spatial resolution CO emission estimates that show slightly smaller IAV due to fires compared to the Global Fire Emissions Database (GFED3) prior emissions. South American dry season (August and September) biomass burning emission estimates amount to 60, 92, 42, 16 and 93 Tg CO/yr for 2006 to 2010, respectively. Moreover, CO emissions probably associated with pre‐harvest burning of sugar cane plantations in São Paulo state are underestimated in current inventories by 50–100%. We conclude that climatic conditions (such as the widespread drought in 2010) seem the most likely cause for the IAV in biomass burning CO emissions. However, socio‐economic factors (such as the growing global demand for soy, beef and sugar cane ethanol) and associated deforestation fires, are also likely as drivers for the IAV of CO emissions, but are difficult to link directly to CO emissions.
The role of ocean cooling in setting glacial southern source bottom water salinity
Authors: Miller M. D. , Adkins J. F. , Menemenlis D. , Schodlok M. P.
Published: June 2012

At the Last Glacial Maximum (LGM), the salinity contrast between northern source deep water and southern source bottom water was reversed with respect to the contrast today. Additionally, Glacial Southern Source Bottom Water (GSSBW) was saltier than Antarctic Bottom Water (AABW), over and above the difference implied by the mean sea level change. This study examines to what extent cold temperatures, through their effect on ice formation and melting, could have caused these differences. Computational sensitivity experiments using a coupled ice shelf cavity–sea ice–ocean model are performed in a Weddell Sea domain, as a representative case study for bottom water formation originating from Antarctic continental shelves. Ocean temperatures at the domain open boundaries are systematically lowered to determine the sensitivity of Weddell Sea water mass properties to a range of cool ocean temperatures. The steady state salinities differ between experiments due to temperature‐induced responses of ice shelf and sea ice melting and freezing, evaporation and open boundary fluxes. The results of the experiments indicate that reduced ocean temperature can explain up to 30% of the salinity difference between GSSBW and AABW, primarily due to decreased ice shelf melting. The smallest and most exposed ice shelves, which abut narrow continental shelves, have the greatest sensitivity to the ocean temperature changes, suggesting that at the LGM there could have been a shift in geographical site dominance in bottom water formation. More sea ice is formed and exported in the cold ocean experiments, but the effect of this on salinity is negated by an equal magnitude reduction in evaporation.
Three-dimensional photoluminescence mapping and emission anisotropy of single gold nanorods
Authors: Wackenhut Frank , Virgilio Failla Antonio , Züchner Tina , Steiner Mathias , Meixner Alfred J.
Published: June 2012

We use raster-scanning confocal microscopy in combination with radially and azimuthally polarized laser excitation for mapping the three-dimensional (3D) orientation of individual spatially isolated gold nanorods (GNRs). The simultaneous acquisition of both the elastic scattering patterns and the one-photon luminescence patterns of the same GNR allows for determining both the particle position and the orientation with high precision. By analyzing experimental patterns and comparing them to theoretical results obtained by computer simulations, we establish a complete 3D photoluminescence map of single GNRs. Both elastic scattering and luminescence patterns of the same particle are found to display modifications of the refractive index of the dielectric environment. The polarization dependence of GNRs photoluminescence suggests a plasmon-mediated process.
Billiard dynamics: An updated survey with the emphasis on open problems
Authors: Gutkin Eugene
Published: June 2012

This is an updated and expanded version of our earlier survey article [E. Gutkin, “Billiard dynamics: a survey with the emphasis on open problems,” Regular Chaotic Dyn. 8, 1–13 (2003)]. Section I introduces the subject matter. Sections II–IV expose the basic material following the paradigm of elliptic, hyperbolic, and parabolic billiard dynamics. In Sec. V, we report on the recent work pertaining to the problems and conjectures exposed in the survey [E. Gutkin, “Billiard dynamics: a survey with the emphasis on open problems,” Regular Chaotic Dyn. 8, 1–13 (2003)]. Besides, in Sec. V we formulate a few additional problems and conjectures. The bibliography has been updated and considerably expanded.
The geometry of inertial particle mixing in urban flows, from deterministic and random displacement models
Authors: Tang Wenbo , Knutson Brent , Mahalov Alex , Dimitrova Reneta
Published: June 2012

We use Lagrangian measures, depicted by finite-time Lyapunov exponents, to characterize transport patterns of inertial pollutant particles formed in urban flows. Motivated by actual events we focus on flows in realistic urban geometry. Both deterministic and stochastic particle transport patterns have been identified, as inertial Lagrangian coherent structures. For the deterministic case, the organizing structures are well-defined and we extract them at different hours of a day to reveal the variability of coherent patterns. For the stochastic case, we use a random displacement model for fluid particles and derive the governing equation for inertial particles to examine the change in organizing structures due to “zeroth-order” random noise. We find that, (1) the Langevin equation for inertial particles can be reduced to a random displacement model; (2) using random noise based on inhomogeneous turbulence, whose diffusivity is derived from k − ε models, major coherent structures survive to organize local flow patterns and weaker structures are smoothed out due to random motion.
Scanning transmission X-ray microscopy and X-ray absorption near-edge structure studies of N-doped carbon nanotubes sealed with N2 gas
Authors: Xie Tian , Zhao Yu , Zhong Jun , Hu Zheng , Sun Xuhui
Published: June 2012

N-doped carbon nanotubes (NCNTs) were synthesized and their electronic structures have been explored by X-ray absorption near-edge structure (XANES) spectroscopy. With a surface sensitive mode, XANES confirms the N-doping in NCNTs. However, with a more bulk sensitive detection mode of XANES, large amount of gaseous N2 have been found to be sealed in NCNTs, even in a high vacuum environment. The encapsulation of the ferrocene residues in carbon nanotubes had been revealed by scanning transmission X-ray microscopy (STXM), which may help for the N2 sealing. The results suggest that the easily sealed gas should be taken into consideration for CNT-based applications.
Particle-in-cell simulations of particle energization from low Mach number fast mode shocks
Authors: Park Jaehong , Workman Jared C. , Blackman Eric G. , Ren Chuang , Siller Robert
Published: June 2012

Astrophysical shocks are often studied in the high Mach number limit but weakly compressive fast shocks can occur in magnetic reconnection outflows and are considered to be a site of particle energization in solar flares. Here we study the microphysics of such perpendicular, low Mach number collisionless shocks using two-dimensional particle-in-cell simulations with a reduced ion/electron mass ratio and employ a moving wall boundary method for initial generation of the shock. This moving wall method allows for more control of the shock speed, smaller simulation box sizes, and longer simulation times than the commonly used fixed wall, reflection method of shock formation. Our results, which are independent of the shock formation method, reveal the prevalence shock drift acceleration (SDA) of both electron and ions in a purely perpendicular shock with Alfvén Mach number MA=6.8 and ratio of thermal to magnetic pressure β=8. We determine the respective minimum energies required for electrons and ions to incur SDA. We derive a theoretical electron distribution via SDA that compares to the simulation results. We also show that a modified two-stream instability due to the incoming and reflecting ions in the shock transition region acts as the mechanism to generate collisionless plasma turbulence that sustains the shock.
Angular emission of ions and mass deposition from femtosecond and nanosecond laser-produced plasmas
Authors: Verhoff B. , Harilal S. S. , Hassanein A.
Published: June 2012

We investigated the angular distribution of ions and atoms emanating from femto- and nanosecond laser-produced metal plasmas under similar laser fluence conditions. For producing plasmas, aluminum targets are ablated in vacuum employing pulses from a Ti:Sapphire ultrafast laser (40 fs, 800 nm) and an Nd:YAG laser (6 ns, 1064 nm). The angular distribution of ion emission as well as the kinetic energy distribution is characterized by a Faraday cup, while a quartz microbalance is used for evaluating deposited mass. The ion and deposited mass features showed that fs laser ablated plasmas produced higher kinetic energy and more mass per pulse than ns plumes over all angles. The ion flux and kinetic energy studies show fs laser plasmas produce narrower angular distribution while ns laser plasmas provide narrower energy distribution.
Quantum Monte Carlo study of high-pressure cubic TiO2
Authors: Abbasnejad M. , Shojaee E. , Mohammadizadeh M. R. , Alaei M. , Maezono Ryo
Published: June 2012

We have studied the high-pressure cubic fluorite polymorph of TiO2 (c-TiO2) using the diffusion Monte Carlo (DMC) method. The estimated bulk modulus is within the range reported previously in density functional studies, high, but does not rival that of diamond. The calculated excitation energies within DMC are consistent with the results of GW approximation. The infrared frequency of c-TiO2, obtained via the frozen phonon method within DMC, shows non-negligible anharmonicity. This suggests that c-TiO2 might be stabilized if this anharmonicity is considered. Our DMC results could help to establish more accurate results for c-TiO2 compared with the widely-scattered mean-field results.
The study of amplitude death in globally delay-coupled nonidentical systems based on order parameter expansion
Authors: Yao Chenggui , Zou Wei , Zhao Qi
Published: June 2012

The method of order parameter expansion is used to study the dynamical behavior in the globally delay-coupled nonidentical systems. Using the Landau-Stuart periodic system and Rössler chaotic oscillator to construct representative systems, the method can identify the boundary curves of amplitude death island analytically in the parameter space of the coupling and time delay. Furthermore, the parameter mismatch (diversity) effect on the size of island is investigated numerically. For the case of coupled chaotic Rössler systems with different timescales, the diversity increases the domain of death island monotonically. However, for the case of delay-coupled Landua-Stuart periodic systems with different frequencies, the average frequency turns out to be a critical role that determines change of size with the increase of diversity.
Field-dependent activation energy of nucleation and switching in phase change memory
Authors: Li J. M. , Yang H. X. , Lim K. G.
Published: June 2012

Exothermal resistance measurement reveals that the phase transition of Ge2Sb2Te5 phase change memory (PCM) can take place far below the traditional crystallization temperature. The activation energy of nucleation is no longer a constant and highly dependent on applied electric fields. The field-dependent activation energy becomes much lower with higher applied field. Further, the field-dependent activation energy can be described by an exponential function of the applied fields. These findings provide physical fundamentals for analysis of nucleation switching mechanism of PCM. A switching model has been developed and the simulated current-voltage curve is in good agreement with the experimental measurement.
Growth, optical and magnetic behavior of YMn0.35In0.65O3 thin film
Authors: Mangalam R. V. K. , Smith Andrew E. , Boudin S. , McLoughlin C. , Subramanian M. A. , Prellier W.
Published: June 2012

The growth of YMn0.35In0.65O3 thin films and their optical and magnetic behavior are reported. The YMn0.35In0.65O3 thin film grows along the (0001) orientation with hexagonal structure similar to YMnO3 on c-plane sapphire. The film shows paramagnetic behavior in the temperature range measured. The film exhibits a blue color due to the electronic transition in the red-green region of the visible spectrum. The development of such a relatively low cost, eco-friendly and highly stable chromophore can be used as a blue filter layer in color filter array.
Eye of the Beholder: Symmetry Perception in Social Judgments Based on Whole Body Displays
Authors: Brown Jennifer Rees , van der Zwan Rick , Brooks Anna
Published: June 2012

External bilateral symmetry is a biological marker of normal development and is considered a signal of health and attractiveness across species. Because most human interactions are dynamic, it was hypothesized that observers would be able to perceive spatiotemporal symmetry—symmetry in motion—in human point-light walkers. It was also hypothesized that observers would rate symmetrical walkers as healthy and attractive. Symmetrical and asymmetrical figures were presented to adult participants ( n = 22) in motion and as static images with motion implied. Static symmetry was readily perceived, and symmetrical figures were judged significantly healthier and more attractive than asymmetrical figures. However, observers were unable to discriminate symmetry in dynamic presentations. These data provide preliminary evidence of a temporal summation window for a dynamic symmetry perception.
Induction of hepatocellular carcinoma by in vivo gene targeting
Authors: Wang Pei-Rong , Xu Mei , Toffanin Sara , Li Yi , Llovet Josep M. , Russell David W.
Published: June 2012

The distinct phenotypic and prognostic subclasses of human hepatocellular carcinoma (HCC) are difficult to reproduce in animal experiments. Here we have used in vivo gene targeting to insert an enhancer-promoter element at an imprinted chromosome 12 locus in mice, thereby converting ∼1 in 20,000 normal hepatocytes into a focus of HCC with a single genetic modification. A 300-kb chromosomal domain containing multiple mRNAs, snoRNAs, and microRNAs was activated surrounding the integration site. An identical domain was activated at the syntenic locus in a specific molecular subclass of spontaneous human HCCs with a similar histological phenotype, which was associated with partial loss of DNA methylation. These findings demonstrate the accuracy of in vivo gene targeting in modeling human cancer and suggest future applications in studying various tumors in diverse animal species. In addition, similar insertion events produced by randomly integrating vectors could be a concern for liver-directed human gene therapy.
Arabidopsis
ARF-GTP exchange factor, GNOM, mediates transport required for innate immunity and focal accumulation of syntaxin PEN1
Authors: Nielsen Mads Eggert , Feechan Angela , Böhlenius Henrik , Ueda Takashi , Thordal-Christensen Hans
Published: June 2012

Penetration resistance to powdery mildew fungi, conferred by localized cell wall appositions (papillae), is one of the best-studied processes in plant innate immunity. The syntaxin PENETRATION (PEN)1 is required for timely appearance of papillae, which contain callose and extracellular membrane material, as well as PEN1 itself. Appearance of membrane material in papillae suggests secretion of exosomes. These are potentially derived from multivesicular bodies (MVBs), supported by our observation that ARA6-labeled organelles assemble at the fungal attack site. However, the trafficking components that mediate delivery of extracellular membrane material are unknown. Here, we show that the delivery is independent of PEN1 function. Instead, we find that application of brefeldin (BF)A blocks the papillary accumulation of GFP-PEN1–labeled extracellular membrane and callose, while impeding penetration resistance. We subsequently provide evidence indicating that the responsible BFA-sensitive ADP ribosylation factor–GTP exchange factor (ARF-GEF) is GNOM. Firstly, analysis of the transheterozygote
gnom

B4049/emb30-1

(
gnom

B

/E

) mutant revealed a delay in papilla formation and reduced penetration resistance. Furthermore, a BFA-resistant version of GNOM restored the BFA-sensitive papillary accumulation of GFP-PEN1 and callose. Our data, therefore, provide a link between GNOM and disease resistance. We suggest that papilla formation requires rapid reorganization of material from the plasma membrane mediated by GNOM. The papilla material is subsequently presumed to be sorted into MVBs and directed to the site of fungal attack, rendering the epidermal plant cell inaccessible for the invading powdery mildew fungus.
Evolutionarily conserved glycan signal to degrade aberrant brassinosteroid receptors in
Arabidopsis
Authors: Hong Zhi , Kajiura Hiroyuki , Su Wei , Jin Hua , Kimura Akihisa , Fujiyama Kazuhito , Li Jianming
Published: June 2012

Asparagine-linked glycans (N-glycans) are crucial signals for protein folding, quality control, and endoplasmic reticulum (ER)-associated degradation (ERAD) in yeast and mammals. Although similar ERAD processes were reported in plants, little is known about their biochemical mechanisms, especially their relationships with N-glycans. Here, we show that a missense mutation in the
Arabidopsis EMS-mutagenized bri1 suppressor 3
(
EBS3
) gene suppresses a dwarf mutant,
bri1-9,
the phenotypes of which are caused by ER retention and ERAD of a brassinosteroid receptor, BRASSINOSTEROID-INSENSITIVE 1 (BR1).
EBS3
encodes the
Arabidopsis
ortholog of the yeast asparagine-linked glycosylation 9 (ALG9), which catalyzes the ER luminal addition of two terminal α1,2 mannose (Man) residues in assembling the three-branched N-glycan precursor [glucose(Glc)]
3
(Man)
9
[
N
-acetylglucosamine(GlcNAc)]
2
. Consistent with recent discoveries revealing the importance of the Glc
3
Man
9
GlcNAc
2
C-branch in generating an ERAD signal, the
ebs3-1
mutation prevents the Glc
3
Man
9
GlcNAc
2
assembly and inhibits the ERAD of bri1-9. By contrast, overexpression of
EBS4
in
ebs3-1 bri1-9,
which encodes the
Arabidopsis
ortholog of the yeast ALG12 catalyzing the ER luminal α1,6 Man addition, adds an α1,6 Man to the truncated N-glycan precursor accumulated in
ebs3-1 bri1-9
, promotes the bri1-9 ERAD, and neutralizes the
ebs3-1
suppressor phenotype. Furthermore, a transfer (T)-DNA insertional
alg3-T2
mutation, which causes accumulation of an even smaller N-glycan precursor carrying a different exposed α1,6 Man, promotes the ERAD of bri1-9 and enhances its dwarfism. Taken together, our results strongly suggest that the glycan signal to mark an ERAD client in
Arabidopsis
is likely conserved to be an α1,6 Man-exposed N-glycan.
Axon injury and stress trigger a microtubule-based neuroprotective pathway
Authors: Chen Li , Stone Michelle C. , Tao Juan , Rolls Melissa M.
Published: June 2012

Axon injury elicits profound cellular changes, including axon regeneration. However, the full range of neuronal injury responses remains to be elucidated. Surprisingly, after axons of
Drosophila
dendritic arborization neurons were severed, dendrites were more resistant to injury-induced degeneration. Concomitant with stabilization, microtubule dynamics in dendrites increased. Moreover, dendrite stabilization was suppressed when microtubule dynamics was dampened, which was achieved by lowering levels of the microtubule nucleation protein γ-tubulin. Increased microtubule dynamics and global neuronal stabilization were also activated by expression of expanded polyglutamine (poly-Q) proteins SCA1, SCA3, and huntingtin. In all cases, dynamics were increased through microtubule nucleation and depended on JNK signaling, indicating that acute axon injury and long-term neuronal stress activate a common cytoskeleton-based stabilization program. Reducing levels of γ-tubulin exacerbated long-term degeneration induced by SCA3 in branched sensory neurons and in a well established
Drosophila
eye model of poly-Q–induced neurodegeneration. Thus, increased microtubule dynamics can delay short-term injury-induced degeneration, and, in the case of poly-Q proteins, can counteract progressive longer-term degeneration. We conclude that axon injury or stress triggers a microtubule-based neuroprotective pathway that stabilizes neurons against degeneration.
Conditional ablation of CD205
+
conventional dendritic cells impacts the regulation of T-cell immunity and homeostasis in vivo
Authors: Fukaya Tomohiro , Murakami Ryuichi , Takagi Hideaki , Sato Kaori , Sato Yumiko , Otsuka Haruna , Ohno Michiko , Hijikata Atsushi , Ohara Osamu , Hikida Masaki , Malissen Bernard , Sato Katsuaki
Published: June 2012

Dendritic cells (DCs) are composed of multiple subsets that play a dual role in inducing immunity and tolerance. However, it is unclear how CD205
+
conventional DCs (cDCs) control immune responses in vivo. Here we generated knock-in mice with the selective conditional ablation of CD205
+
cDCs. CD205
+
cDCs contributed to antigen-specific priming of CD4
+
T cells under steady-state conditions, whereas they were dispensable for antigen-specific CD4
+
T-cell responses under inflammatory conditions. In contrast, CD205
+
cDCs were required for antigen-specific priming of CD8
+
T cells to generate cytotoxic T lymphocytes (CTLs) mediated through cross-presentation. Although CD205
+
cDCs were involved in the thymic generation of CD4
+
regulatory T cells (Tregs), they maintained the homeostasis of CD4
+
Tregs and CD4
+
effector T cells in peripheral and mucosal tissues. On the other hand, CD205
+
cDCs were involved in the inflammation triggered by Toll-like receptor ligand as well as bacterial and viral infections. Upon microbial infections, CD205
+
cDCs contributed to the cross-priming of CD8
+
T cells for generating antimicrobial CTLs to efficiently eliminate pathogens, whereas they suppressed antimicrobial CD4
+
T-cell responses. Thus, these findings reveal a critical role for CD205
+
cDCs in the regulation of T-cell immunity and homeostasis in vivo.
Photosynthetic sucrose acts as cotyledon-derived long-distance signal to control root growth during early seedling development in
Arabidopsis
Authors: Kircher Stefan , Schopfer Peter
Published: June 2012

The most hazardous span in the life of green plants is the period after germination when the developing seedling must reach the state of autotrophy before the nutrients stored in the seed are exhausted. The need for an economically optimized utilization of limited resources in this critical period is particularly obvious in species adopting the dispersal strategy of producing a large amount of tiny seeds. The model plant
Arabidopsis thaliana
belongs to this category.
Arabidopsis
seedlings promote root development only in the light. This response to light has long been recognized and recently discussed in terms of an organ-autonomous feature of photomorphogenesis directed by the red/blue light absorbing photoreceptors phytochrome and cryptochrome and mediated by hormones such as auxin and/or gibberellin. Here we show that the primary root of young
Arabidopsis
seedlings responds to an interorgan signal from the cotyledons and that phloem transport of photosynthesis-derived sugar into the root tip is necessary and sufficient for the regulation of root elongation growth by light.
Barium ions selectively activate BK channels via the Ca
2+
-bowl site
Authors: Zhou Yu , Zeng Xu-Hui , Lingle Christopher J.
Published: June 2012

Activation of Ca
2+
-dependent BK channels is increased via binding of micromolar Ca
2+
to two distinct high-affinity sites per BK α-subunit. One site, termed the Ca
2+
bowl, is embedded within the second RCK domain (RCK2; regulator of conductance for potassium) of each α-subunit, while oxygen-containing residues in the first RCK domain (RCK1) have been linked to a separate Ca
2+
ligation site. Although both sites are activated by Ca
2+
and Sr
2+
, Cd
2+
selectively favors activation via the RCK1 site. Divalent cations of larger ionic radius than Sr
2+
are thought to be ineffective at activating BK channels. Here we show that Ba
2+
, better known as a blocker of K
+
channels, activates BK channels and that this effect arises exclusively from binding at the Ca
2+
-bowl site. Compared with previous estimates for Ca
2+
bowl–mediated activation by Ca
2+
, the affinity of Ba
2+
to the Ca
2+
bowl is reduced about fivefold, and coupling of binding to activation is reduced from ∼3.6 for Ca
2+
to about ∼2.8 for Ba
2+
. These results support the idea that ionic radius is an important determinant of selectivity differences among different divalent cations observed for each Ca
2+
-binding site.
Degradation and resilience in Louisiana salt marshes after the BP–Deepwater Horizonoil spill
Authors: Silliman Brian R. , van de Koppel Johan , McCoy Michael W. , Diller Jessica , Kasozi Gabriel N. , Earl Kamala , Adams Peter N. , Zimmerman Andrew R.
Published: June 2012

More than 2 y have passed since the BP–Deepwater Horizonoil spill in the Gulf of Mexico, yet we still have little understanding of its ecological impacts. Examining effects of this oil spill will generate much-needed insight into how shoreline habitats and the valuable ecological services they provide (e.g., shoreline protection) are affected by and recover from large-scale disturbance. Here we report on not only rapid salt-marsh recovery (high resilience) but also permanent marsh area loss after the BP–Deepwater Horizonoil spill. Field observations, experimental manipulations, and wave-propagation modeling reveal that (i) oil coverage was primarily concentrated on the seaward edge of marshes; (ii) there were thresholds of oil coverage that were associated with severity of salt-marsh damage, with heavy oiling leading to plant mortality; (iii) oil-driven plant death on the edges of these marshes more than doubled rates of shoreline erosion, further driving marsh platform loss that is likely to be permanent; and (iv) after 18 mo, marsh grasses have largely recovered into previously oiled, noneroded areas, and the elevated shoreline retreat rates observed at oiled sites have decreased to levels at reference marsh sites. This paper highlights that heavy oil coverage on the shorelines of Louisiana marshes, already experiencing elevated retreat because of intense human activities, induced a geomorphic feedback that amplified this erosion and thereby set limits to the recovery of otherwise resilient vegetation. It thus warns of the enhanced vulnerability of already degraded marshes to heavy oil coverage and provides a clear example of how multiple human-induced stressors can interact to hasten ecosystem decline.
How the speed of motor-response decisions, but not focal-attentional selection, differs as a function of task set and target prevalence
Authors: Töllner Thomas , Rangelov Dragan , Müller Hermann J.
Published: June 2012

Over the last decades, the visual-search paradigm has provided a powerful test bed for competing theories of visual selective attention. However, the information required to decide upon the correct motor response differs fundamentally across experimental studies, being based, for example, on the presence, spatial location, or identity of the target item. This variability raises the question as to whether estimates of the time taken for (
i
) focal-attentional selection, (
ii
) deciding on the motor response, and (
iii
) response execution generalize across search studies or are specific to the demands of a particular task set. To examine this issue, we presented physically identical stimulus material in four different search task conditions, requiring target localization, detection, discrimination, or compound responses, and combined mental chronometry with two specific electroencephalographic brain responses that are directly linkable to either preattentive or postselective levels of visual processing. Behaviorally, reactions were fastest for localization, slowest for compound responses, and of intermediate speed for detection and discrimination responses. At the electroencephalographic level, this effect of task type manifested in the timing of the stimulus- and response-locked lateralized readiness potential (indexing motor-response decisions), but not posterior contralateral negativity (indexing focal-attentional selection), component. This result demonstrates that only the stage of preattentive visual coding generalizes across task settings, whereas processes that follow focal target selection are dependent on the nature of the task. Consequently, this task set-specific pattern has fundamental implications for all types of experimental paradigms, within and beyond visual search, that require humans to generate motor responses on the basis of external sensory stimulation.
Age and Growth of Atlantic Sturgeon in the James River, Virginia, 1997–2011
Authors: Balazik Matthew T. , McIninch Stephen P. , Garman Greg C. , Latour Robert J.
Published: June 2012

Historically the Chesapeake Bay supported a large population of Atlantic sturgeonAcipenser oxyrinchus, but loss of suitable spawning habitat and overfishing coincided with dramatic in‐system declines throughout the 20th century. Atlantic sturgeon harvest moratoriums were implemented in 1974 for Virginia waters and were expanded coastwide in 1998. In 1997, researchers became aware that commercial fishers in the James River, a tributary of the Chesapeake Bay, were catching juvenile and subadult Atlantic sturgeon as bycatch in various fisheries. Genetic studies showed that the Chesapeake Bay population has maintained genetic integrity and qualifies as a distinct population segment. Between 2007 and 2011, almost 150 adults have been caught in the tidal–freshwater portion of the James River during putative spawning runs. Pectoral fin spines from juveniles and subadults collected in the Burwell Bay (rkm 40) and Cobham Bay (rkm 60) areas and mature adult samples from vessel strikes in freshwater around or above rkm 120 were analyzed to create a length‐at‐age curve for Atlantic sturgeon in the James River. Five models were used to analyze the data, and the double von Bertalanffy (k1= 0.054,k2= 0.097,t1= −2.85,t2= 1.09,tp= 6.03 years,L∞= 2241 mm) provided the best fit to the observed data. We estimated an increase in growth coefficient attp, which could be an artifact of low sample size or due to ontogenetic changes in habitat use as older fish spend more time in oceanic waters than younger fish. Atlantic sturgeon in the 6–9 year age range are rarely encountered in the James River compared with younger and older age‐classes, so a more in‐depth analysis of the increased growth coefficient would require ocean sampling.
Brook Trout Movement in Response to Temperature, Flow, and Thermal Refugia within a Complex Appalachian Riverscape
Authors: Petty J. Todd , Hansbarger Jeff L. , Huntsman Brock M. , Mazik Patricia M.
Published: June 2012

We quantified movements of brook trout Salvelinus fontinalis and brown trout Salmo trutta in a complex riverscape characterized by a large, open‐canopy main stem and a small, closed‐canopy tributary in eastern West Virginia, USA. Our objectives were to quantify the overall rate of trout movement and relate movement behaviors to variation in streamflow, water temperature, and access to coldwater refugia. The study area experienced extremely high seasonal, yearly, and among‐stream variability in water temperature and flow. The relative mobility of brook trout within the upper Shavers Fork watershed varied significantly depending on whether individuals resided within the larger main stem or the smaller tributary. The movement rate of trout inhabiting the main stem during summer months (50 m/d) was an order of magnitude higher than that of tributary fish (2 m/d). Movement rates of main‐stem‐resident brook trout during summer were correlated with the maximum water temperature experienced by the fish and with the fish's initial distance from a known coldwater source. For main‐stem trout, use of microhabitats closer to cover was higher during extremely warm periods than during cooler periods; use of microhabitats closer to cover during warm periods was also greater for main‐stem trout than for tributary inhabitants. Main‐stem‐resident trout were never observed in water exceeding 19.5°C. Our study provides some of the first data on brook trout movements in a large Appalachian river system and underscores the importance of managing trout fisheries in a riverscape context. Brook trout conservation in this region will depend on restoration and protection of coldwater refugia in larger river main stems as well as removal of barriers to trout movement near tributary and main‐stem confluences.
Using Needs Assessment to Develop Curricula for Screening, Brief Intervention, and Referral to Treatment (SBIRT) in Academic and Community Health Settings
Authors: Satre Derek D. , McCance-Katz Elinore F. , Moreno-John Gina , Julian Katherine A. , O'Sullivan Patricia S. , Satterfield Jason M.
Published: June 2012

This article describes the use of a brief needs assessment survey in the development of alcohol and drug screening, brief intervention, and referral to treatment (SBIRT) curricula in 2 health care settings in the San Francisco Bay Area. The samples included university medical center faculty ( n = 27) and nonphysician community health and social service providers in a nearby suburban county ( n = 21). Informed by curriculum development theory and motivational interviewing strategies, questions regarding clinical and educational priorities, perceived importance and confidence with screening and intervention techniques, and referral resource availability were included. Medical center faculty expressed greater concern about limited appointment time ( P = .003), adequacy of training ( P = .025), and provider confidence ( P = .038) as implementation obstacles and had lower confidence in delivering SBIRT ( P = .046) and providing treatment referrals ( P = .054) than community providers. The authors describe their approach to integrating needs assessment results into subsequent curriculum development. Findings highlight potential differences between physician and nonphysician training needs.
Application of a Bioenergetics Model for Hatchery Production: Largemouth Bass Fed Commercial Feeds
Authors: Csargo Isak J , Brown Michael L , Chipps Steven R
Published: June 2012

Fish bioenergetics models based on natural prey items have been widely used to address research and management questions. However, few attempts have been made to evaluate and apply bioenergetics models to hatchery-reared fish receiving commercial feeds that contain substantially higher energy densities than natural prey. In this study, we evaluated a bioenergetics model for age-0 largemouth bass Micropterus salmoides reared on four commercial feeds. Largemouth bass (n ≈ 3,504) were reared for 70 d at 25°C in sixteen 833-L circular tanks connected in parallel to a recirculation system. Model performance was evaluated using error components (mean, slope, and random) derived from decomposition of the mean square error obtained from regression of observed on predicted values. Mean predicted consumption was only 8.9% lower than mean observed consumption and was similar to error rates observed for largemouth bass consuming natural prey. Model evaluation showed that the 97.5% joint confidence region included the intercept of 0 (−0.43 ± 3.65) and slope of 1 (1.08 ± 0.20), which indicates the model accurately predicted consumption. Moreover model error was similar among feeds (P = 0.98), and most error was probably attributable to sampling error (unconsumed feed), underestimated predator energy densities, or consumption-dependent error, which is common in bioenergetics models. This bioenergetics model could provide a valuable tool in hatchery production of largemouth bass. Furthermore, we believe that bioenergetics modeling could be useful in aquaculture production, particularly for species lacking historical hatchery constants or conventional growth models.
Effectiveness of Copper Sulfate and Potassium Permanganate on Channel Catfish Infected with Flavobacterium columnare
Authors: Farmer Bradley D , Beck Benjamin H , Straus David L
Published: June 2012

Copper sulfate (CuSO4) and potassium permanganate (KMnO4) were evaluated for their effectiveness to curtail mortality and decrease bacterial load in fish tissues and water in channel catfish Ictalurus punctatus infected with Flavobacterium columnare, the causative agent of columnaris. Fish (average size, 16.6 g and 13.7 cm) were obtained from a single culture tank undergoing an epizootic of columnaris and were stocked at a density of 30 fish per tank in each of 12 tanks. The study consisted of three treatments (n = 4 replicates per treatment): an untreated control group, a CuSO4-treated group, and a KMnO4-treated group. Treatment rates were 2.1 mg/L CuSO4 and 3.0 mg/L KMnO4 and were applied on three consecutive days at 24-h intervals. Caudal fin, gill, and liver samples were taken from one fish of each replication 24 h after the last treatment for analysis by quantitative real time PCR. A significant improvement in survival was noted among fish treated with CuSO4 (72.7%) compared with the control fish (38.5%) and the KMnO4-treated fish (52.2%). Survival of the KMnO4-treated fish was not significantly different from the control. Quantitative PCR indicated a significant reduction of bacteria in the water after the first and second treatments of both therapeutants; no difference was detected in fish tissues. Histological analysis of gill samples 24 h after the last treatment indicated that CuSO4-treated fish exhibited significantly less gill damage than untreated controls and there was no difference in KMnO4-treated fish. Copper sulfate therapy significantly improved survival, reduced the number of bacteria in the water, and reduced gill pathologies associated with F. columnare infection in channel catfish.
Book Reviews
Authors: CLARKE Anji
Published: June 2012

Copyright Law for Writers, Editors and Publishers Gillian Davies in association with Ian Bloom London, A. & C. Black Publishers, 2011, 128pp. ISBN: 978‐1408128145, £14.99 (pbk)