bluuebunny/crossref_metadata_2025 huggingface dataset:
The contribution of eddies to striations in absolute dynamic topography
Authors: Buckingham C. E. , Cornillon P. C.
Published: December 2012

Distinct 4 year averages of absolute dynamic topography reveal striations in all ocean basins during 1993–2008. Striations are alternating mesoscale jet‐like structures observed in time‐averaged zonal geostrophic velocity, . They are characterized by speeds O(1 cm s–1) and are nominally separated by 200 km in the meridional direction. Similar patterns have been observed in sea level anomaly, mean dynamic topography, and Argo float measurements. Use of a tracked‐eddy database in concert with a contour identification and eddy removal algorithm demonstrates that eddies are a dominant source of striations in in the South Pacific (20°S–50°S, 200°E–280°E). Eddies with lifetimes ≥ 4 weeks account for 46–57% of the variance in and correlation coefficients between total and eddy‐only are 0.90–0.93. Attention is given to the ability of the algorithm to correctly identify eddies and suggests that a more appropriate bound on the variance due to eddies is ∼ 30–70%. This permits the existence of latent zonal jets and/or β‐plumes. Additional findings of the study include (1) a large number of eddies having a broad range of amplitudes and scales contribute most to the eddy‐induced patterns and (2) the standard deviation of does not decay inversely with averaging period as proposed by a model of random eddies.
Seasonal mixed‐layer salinity balance in the tropical Atlantic Ocean: Mean state and seasonal cycle
Authors: Da‐Allada C. Y. , Alory G. , du Penhoat Y. , Kestenare E. , Durand F. , Hounkonnou N. M.
Published: December 2012

We investigate the causes of the seasonal cycle of the near‐surface salinity using a mixed‐layer salinity model and a combination of satellite products, atmospheric reanalyses, and in situ observations for the period 2000–2008, in the tropical Atlantic Ocean. We find that the balance differs from one region to another. In the western tropical Atlantic, it is controlled by horizontal advection from March to November and by freshwater flux and entrainment for the rest of the year. In the central tropical Atlantic, it is mainly due to the strong contribution of precipitation in agreement with previous results. In the northeastern tropical Atlantic, all terms contribute to the mixed layer salinity between December and March; during the rest of the year, precipitation and zonal advection mainly control the balance. In the Gulf of Guinea, it is driven by freshwater flux from October to February; from March to July, it is controlled by horizontal advection and entrainment; from August to September, mixed‐layer salinity variability is weak. Finally, in the Congo region, it is driven by freshwater flux (precipitation and runoff from Congo River) from September to December, by horizontal advection during January to March, and by vertical entrainment during the rest of the year (April to August). There are some discrepancies between observed and modeled salinity tendencies. Some of them are due to our model formulation, which does not explicitly account for the effect of vertical diffusion. Uncertainties of observation products, which force the model, are also sources of errors.
Hydrographs of a Martian flood from a breached crater lake, with insights about flow calculations, channel erosion rates, and chasma growth
Authors: Coleman Neil M.
Published: December 2012

The Elaver Vallis channels provide a unique opportunity to develop calibrated hydrographs for a Martian flood. Groundwater filled Morella Crater until the enclosed lake overtopped the rim, confirming that the groundwater potentiometric surface exceeded 1771 m. The overtopping flow rapidly breached the crater wall, catastrophically drained the lake, and eroded a broad scabland and two main channels. Laser altimeter data were used to calculate a preflood lake volume of 2.216 × 1012 m3. Dam breach methods were used to develop hydrographs of discharge and lake stage over time. The peak discharge was in the range of 1.94 × 107to 3.51 × 107 m3 s–1, depending on the underlying breach erosion scenario. Approximately 95% of the drainable lake volume discharged in 6.4 to 7.5 days. The 240 m deep southern channel entirely formed in 1 to 1.7 days, indicating a mean erosion rate of 0.10 to 0.17 m min–1. The volume of material eroded from the channels was 0.45 of the flood volume, but the actual eroded fraction was probably greater because distant channel reaches were obliterated by the postflood growth of Ganges Chasma. For comparison, flow calculations were performed using open‐channel methods. Channel energy slopes had to be corrected for a postflood tectonic tilt in the regional surface. Comparing the hydrographs to the open‐channel calculations reveals that the northern Elaver Vallis channel as seen today never flowed bank full or even at half its maximum depth because the implied flows would have exceeded the peak discharges.
Grounding line migration and high‐resolution calving dynamics of Jakobshavn Isbræ, West Greenland
Authors: Rosenau R. , Schwalbe E. , Maas H.‐G. , Baessler M. , Dietrich R.
Published: December 2012

We performed three field campaigns in 2004, 2007, and 2010 at the southern margin of the Jakobshavn Isbræ, West Greenland, in order to infer flow velocities and their changes from photogrammetric time‐lapse imagery with a temporal resolution of 20 min and a spatial spacing of about 30 m on the glacier surface. Area‐wide analysis of more than 3000 three‐dimensional trajectories at individual glacier positions allow for both the mapping of the grounding line and the detailed observation of flow variations during major calving events. From 2004 to 2010, the grounding line of Jakobshavn Isbræ retreated 3.5 ± 0.2 km. Considering previously published results, the grounding line retreat amounts to 6 km since 1985. The glacier has an ephemeral floating tongue that can establish during the readvance of the glacier front and break apart after large calving events. Observations of a major calving event show that an acceleration of flow velocities coincides with the onset of the break up during which flow velocities of up to 70 m/d can be reached. Moreover, large vertical displacements of the glacier front in the order of 15 m and lowering of 8 m at positions 500 m beyond the calving front were observed 2 days before the calving event. After the break up, the glacier slowly adjusts to the new boundary conditions within the next 4–5 days. Flow velocity variations caused by calving were detected up to 1 km upstream only which indicates that individual calving events have no immediate effect on the large‐scale glacier dynamics.
Watershed hydrograph model based on surface flow diffusion
Authors: Yang Yang , Endreny Theodore A.
Published: December 2012

Key Points

Developed an analytical diffusion hydrograph model for surface flow

Analyzed model simulation of the hydrograph rising/falling limb and time to peak

Good simulation results for urbanized watershed
Human Violence and Evolutionary Consciousness
Authors: Gorelik Gregory , Shackelford Todd K. , Weekes-Shackelford Viviana A.
Published: December 2012

The evolution and development of adaptations results from the gradual selection of traits that enable organisms to acquire and maintain resources needed for survival and reproduction. We argue that instances of individual, regional, and global violence are rooted in our adaptations to seek, acquire, maintain, and utilize limited resources, regardless of whether such adaptations are currently successful at doing so. However, violence is not the only strategy employed by organisms to acquire resources; cooperation, reciprocity, and social bonding are behaviors that likewise may prove useful in this endeavor. We speculate about how individual adaptations and their byproducts may interact with the adaptations of other individuals and with societal and cultural phenomena, both violently and nonviolently. Finally, we discuss how individual decisions can affect higher level regional and global violence. Individual decisions carry moral weight for the individual in question and for society as a whole. We argue that individual decisions and behaviors can have far-reaching consequences on the well-being of others and that an evolutionary consciousness may help us to understand the effects of our personal choices on the existence of individual and group-level violence.
IL‐7 downregulates IL‐7Rα expression in human CD8 T cells by two independent mechanisms
Authors: Ghazawi Feras M , Faller Elliott M , Sugden Scott M , Kakal Juzer A , MacPherson Paul A
Published: December 2012

Interleukin (IL)‐7 is an essential nonredundant cytokine, and throughout the lifespan of a T‐cell signaling via the IL‐7 receptor influences cell survival, proliferation and differentiation. It is therefore no surprise that expression of the IL‐7 receptor alpha‐chain (CD127) is tightly regulated. We have previously shown that IL‐7 downregulates expression of CD127 at the cell surface and now elucidate the kinetics of that suppression and demonstrate that IL‐7 downregulates CD127 transcripts and surface protein in primary human CD8 T cells by two separate pathways. We show that IL‐7 induces the initial reduction in cell‐surface CD127 protein independent of transcriptional suppression, which is delayed by 40–60 min. Although IL‐7‐mediated downregulation of CD127 transcripts is dependent on Janus kinase (JAK)/STAT5, the early downregulation of surface CD127 protein is independent of JAK activity. The data further illustrate that low levels of IL‐7 induce smaller and transient decreases in CD127 transcripts and surface protein, whereas higher concentrations induce more profound and sustained suppression. Such flexibility in receptor expression likely allows for fine‐tuned immune responses in human CD8 T cells in different microenvironments and in response to different immunological challenges.
A many-electron tight binding method for the analysis of quantum dot systems
Authors: Nielsen Erik , Rahman Rajib , Muller Richard P.
Published: December 2012

We present a method which computes many-electron energies and eigenfunctions by a full configuration interaction, which uses a basis of atomistic tight-binding wave functions. This approach captures electron correlation as well as atomistic effects, and is well suited to solid state quantum dot systems containing few electrons, where valley physics and disorder contribute significantly to device behavior. Results are reported for a two-electron silicon double quantum dot as an example.
Nondestructive characterization of a TiN metal gate: Chemical and structural properties by means of standing-wave hard x-ray photoemission spectroscopy
Authors: Papp C. , Conti G. , Balke B. , Ueda S. , Yamashita Y. , Yoshikawa H. , Uritsky Y. S. , Kobayashi K. , Fadley C. S.
Published: December 2012

Standing-wave (SW) hard x-ray photoemission (HXPS, HAXPES) is applied to a thick (100 Å) film of a metal gate TiN grown on top of a Si/MoSi2 multilayer mirror. The mirror is used to produce a standing wave of 30 Å period that is scanned through the sample by varying the x-ray incidence angle over its 1st-order Bragg condition, thus generating rocking curves of various core-level intensities. The thickness and chemical state of the top, oxidized surface of TiN, as well as the buried interface between TiN and the native oxide on top of the mirror are determined by SW-HXPS. The information provided by SW-HXPS is compared to that obtained by XPS Ar+ depth profile. The SW-HXPS method not only does not require destroying the sample but also provides more quantitative results and a more detailed profile of the interfaces than XPS Ar+ depth profile. Various applications of SW-HXPS to nanoscale multilayer semiconductor systems are thus suggested.
Contact-induced spin polarization in graphene/h-BN/Ni nanocomposites
Authors: Avramov Pavel V. , Kuzubov Alex A. , Sakai Seiji , Ohtomo Manabu , Entani Shiro , Matsumoto Yoshihiro , Naramoto Hiroshi , Eleseeva Natalia S.
Published: December 2012

Atomic and electronic structure of graphene/Ni(111), h-BN/Ni(111) and graphene/h-BN/Ni(111) nanocomposites with different numbers of graphene and h-BN layers and in different mutual arrangements of graphene/Ni and h-BN/Ni at the interfaces was studied using LDA/PBC/PW technique. Using the same technique corresponding graphene, h-BN and graphene/h-BN structures without the Ni plate were calculated for the sake of comparison. It was suggested that C-top:C-fcc and N-top:B-fcc configurations are energetically favorable for the graphene/Ni and h-BN/Ni interfaces, respectively. The Ni plate was found to induce a significant degree of spin polarization in graphene and h-BN through exchange interactions of the electronic states located on different fragments.
Thermal quadrupole method applied to flat and spherical semi-transparent multilayers heated up with a modulated laser beam
Authors: Ordonez-Miranda J. , Alvarado-Gil J. J.
Published: December 2012

The thermal quadrupole method for flat and spherical multilayered systems heated up with a modulated laser beam is developed and analyzed. The obtained results take into account the contribution of the thermal properties and optical absorption coefficient of the component semi-transparent layers as well as their interface thermal resistance, under a fully analytical framework. For opaque layers, they reduced to the results reported in the literature. It is shown that the thermal wave fields for spherical layers reduce to the ones for flat layers, under a proper limit on the radius of the layers. By analyzing the features of the normalized amplitude and phase as a function of the normalized frequency for one- and two-layer systems, simple and useful formulas to determine the optical absorption coefficient of flat and spherical layers are derived. The proposed approach extends the applicability of the thermal quadrupole method to deal with modulated internal heat sources, it allows determining the thermal wave field of any number of layers in a simple way, and therefore, it would be useful to perform the thermal and optical characterization of flat and spherical layered systems by means of photothermal techniques.
Analysis of critical dimensions for axial double heterostructure nanowires
Authors: Geng Hui , Yan Xin , Zhang Xia , Li Junshuai , Huang Yongqing , Ren Xiaomin
Published: December 2012

Critical dimensions for an axial double heterostructure nanowire are studied by using finite-element method based on the energy equilibrium criteria. Results show that the critical dimensions are determined by stress fields generated at two interfaces. The dislocations incline to emerge at higher interface when the indium content is less than 10%, while at lower interface when exceeds 10%. Two critical radiuses are obtained: One is called dislocation-free critical radius, below which the structure is coherent regardless of the thickness. The other is named dislocation-unavoidable critical radius, above which dislocations are always energetically favored. The simulated results are in good agreement with the experimental data. We also find that the dislocation-free critical radius here is smaller than that of single heterostructure, and independent of the mediumlayer thickness. This work may serve as a guide to the fabrication of coherently strained double heterostructure nanowires
Size, composition, and doping effects on In(Ga)As nanowire/Si tunnel diodes probed by conductive atomic force microscopy
Authors: Yang Tao , Hertenberger Simon , Morkötter Stefanie , Abstreiter Gerhard , Koblmüller Gregor
Published: December 2012

We investigate the effect of various parameters on the room–temperature interband tunneling characteristics of molecular beam epitaxy grown, intrinsically n-type In(Ga)As nanowires (NWs) on p-type silicon (Si) substrate using conductive atomic force microscopy. Large interband tunnel currents (>40 kA/cm2) and reduced breakdown voltages are obtained by increasing the p-type substrate doping level to >1 × 1019 cm−3. Current mapping under forward bias reveals a bimodal distribution of NW/Si hetero-junction tunnel diodes exhibiting either negative differential resistance (NDR, Esaki diode) or high excess currents (without NDR). By downscaling the NW diameter from ∼90 nm to ∼25 nm, peak-to-valley current ratios in NDR-type diodes increase and saturate with maximum values of ∼3. Increasing Ga content (xGa up to ∼0.1) in In–rich ternary InGaAs NWs preserves the NDR behavior, while the peak current shifts to lower voltages due to reduced Fermi energy in InGaAs. Band profile calculations were performed to further support these findings.
Ultrafast probing of ejection dynamics of Rydberg atoms and molecular fragments from electronically excited helium nanodroplets
Authors: Bünermann Oliver , Kornilov Oleg , Haxton Daniel J. , Leone Stephen R. , Neumark Daniel M. , Gessner Oliver
Published: December 2012

The ejection dynamics of Rydberg atoms and molecular fragments from electronically excited helium nanodroplets are studied with time-resolved extreme ultraviolet ion imaging spectroscopy. At excitation energies of 23.6 ± 0.2 eV, Rydberg atoms in n = 3 and n = 4 states are ejected on different time scales and with significantly different kinetic energy distributions. Specifically, n = 3 Rydberg atoms are ejected with kinetic energies as high as 0.85 eV, but their appearance is delayed by approximately 200 fs. In contrast, n = 4 Rydberg atoms appear within the time resolution of the experiment with considerably lower kinetic energies. Major features in the Rydberg atom kinetic energy distributions for both principal quantum numbers can be described within a simple elastic scattering model of localized perturbed atomic Rydberg atoms that are expelled from the droplet due to their repulsive interaction with the surrounding helium bath. Time-dependent kinetic energy distributions of He2+ and He3+ ions are presented that support the formation of molecular ions in an indirect droplet ionization process and the ejection of neutral Rydberg dimers on a similar time scale as the n = 3 Rydberg atoms.
Magnetotransport properties of dual MgO barrier magnetic tunnel junctions consisting of CoFeB/FeNiSiB/CoFeB free layers
Authors: Kim D. K. , Cho J. U. , Chun B. S. , Shin K. H. , Lee K. J. , Tsunoda M. , Takahashi M. , Kim Y. K.
Published: December 2012

We report the transport properties of a dual MgO barrier magnetic tunnel junction (DMTJ) where a FeNiSiB layer was inserted in a CoFeB free layer. Upon post-deposition annealing at 330 °C, the tunneling magnetoresistance (TMR) ratio of the DMTJ with a hybrid CoFeB/FeNiSiB/CoFeB free layer reached 195% which is higher than the TMR ratio of 121% from the DMTJ with the single CoFeB free layer. The bias voltage dependence profile was more symmetric for the hybrid case. Boron depth profiling result suggests that the FeNiSiB layer dragged boron atoms more to it rather than letting them diffuse toward CoFeB/MgO interfaces, resulting in improved MTJ performances.
Aluminum oxide–n-Si field effect inversion layer solar cells with organic top contact
Authors: Erickson A. S. , Kedem N. K. , Haj-Yahia A. E. , Cahen D.
Published: December 2012

We demonstrate a solar cell that uses fixed negative charges formed at the interface of n-Si with Al2O3 to generate strong inversion at the surface of n-Si by electrostatic repulsion. Built-in voltages of up to 755 mV are found at this interface. In order to harness this large built-in voltage, we present a photovoltaic device where the photocurrent generated in this inversion layer is extracted via an inversion layer induced by a high work function transparent organic top contact, deposited on top of a passivating and dipole-inducing molecular monolayer. Results of the effect of the molecular monolayer on device performance yield open-circuit voltages of up to 550 mV for moderately doped Si, demonstrating the effectiveness of this contact structure in removing the Fermi level pinning that has hindered past efforts in developing this type of solar cell with n-type Si.
Visual Rotation Axis and Body Position Relative to the Gravitational Direction: Effects on Circular Vection
Authors: Tanahashi Shigehito , Ujike Hiroyasu , Ukai Kazuhiko
Published: December 2012

The visual–vestibular conflict theory asserts that visual–vestibular conflicts reduce vection and that vection strength is reduced with an increasing discrepancy between actual and expected vestibular activity. Most studies support this theory, although researchers have not always accepted them. To ascertain the conditions under which the theory of the visual–vestibular conflict can be applied, we measured circular vection strength accompanied by manipulation of the visual–otolith conflict by setting the axes of visual global motion (pitch, roll, and yaw) as either earth-horizontal or earth-vertical, using three different body positions (supine, left-lateral recumbent, and sitting upright). When the smaller stimulus was used, roll vection strength was greater with the visual–otolith conflict than without it, which contradicts the visual–vestibular conflict theory. We confirmed this result, as observers were able to distinguish circular vection from an illusory body tilt. Moreover, with observers in an upright position, the strength of yaw vection, which does not involve the visual–otolith conflict, increased and was almost equal to that of roll vection, which involves the visual–otolith conflict. This suggests that if the visual stimulus covers the entire visual field, the strength of circular vection around the earth-vertical axis exceeds that around the earth-horizontal axis, which is a finding consistent with the visual–vestibular conflict theory.
G-protein signaling leverages subunit-dependent membrane affinity to differentially control βγ translocation to intracellular membranes
Authors: O’Neill Patrick R. , Karunarathne W. K. Ajith , Kalyanaraman Vani , Silvius John R. , Gautam N.
Published: December 2012

Activation of G-protein heterotrimers by receptors at the plasma membrane stimulates βγ-complex dissociation from the α-subunit and translocation to internal membranes. This intermembrane movement of lipid-modified proteins is a fundamental but poorly understood feature of cell signaling. The differential translocation of G-protein βγ-subunit types provides a valuable experimental model to examine the movement of signaling proteins between membranes in a living cell. We used live cell imaging, mathematical modeling, and in vitro measurements of lipidated fluorescent peptide dissociation from vesicles to determine the mechanistic basis of the intermembrane movement and identify the interactions responsible for differential translocation kinetics in this family of evolutionarily conserved proteins. We found that the reversible translocation is mediated by the limited affinity of the βγ-subunits for membranes. The differential kinetics of the βγ-subunit types are determined by variations among a set of basic and hydrophobic residues in the γ-subunit types. G-protein signaling thus leverages the wide variation in membrane dissociation rates among different γ-subunit types to differentially control βγ-translocation kinetics in response to receptor activation. The conservation of primary structures of γ-subunits across mammalian species suggests that there can be evolutionary selection for primary structures that confer specific membrane-binding affinities and consequent rates of intermembrane movement.
Transition paths, diffusive processes, and preequilibria of protein folding
Authors: Zhang Zhuqing , Chan Hue Sun
Published: December 2012

Fundamental relationships between the thermodynamics and kinetics of protein folding were investigated using chain models of natural proteins with diverse folding rates by extensive comparisons between the distribution of conformations in thermodynamic equilibrium and the distribution of conformations sampled along folding trajectories. Consistent with theory and single-molecule experiment, duration of the folding transition paths exhibits only a weak correlation with overall folding time. Conformational distributions of folding trajectories near the overall thermodynamic folding/unfolding barrier show significant deviations from preequilibrium. These deviations, the distribution of transition path times, and the variation of mean transition path time for different proteins can all be rationalized by a diffusive process that we modeled using simple Monte Carlo algorithms with an effective coordinate-independent diffusion coefficient. Conformations in the initial stages of transition paths tend to form more nonlocal contacts than typical conformations with the same number of native contacts. This statistical bias, which is indicative of preferred folding pathways, should be amenable to future single-molecule measurements. We found that the preexponential factor defined in the transition state theory of folding varies from protein to protein and that this variation can be rationalized by our Monte Carlo diffusion model. Thus, protein folding physics is different in certain fundamental respects from the physics envisioned by a simple transition-state picture. Nonetheless, transition state theory can be a useful approximate predictor of cooperative folding speed, because the height of the overall folding barrier is apparently a proxy for related rate-determining physical properties.
Increased lipolysis and altered lipid homeostasis protect γ-synuclein–null mutant mice from diet-induced obesity
Authors: Millership Steven , Ninkina Natalia , Guschina Irina A. , Norton Jessica , Brambilla Riccardo , Oort Pieter J. , Adams Sean H. , Dennis Rowena J. , Voshol Peter J. , Rochford Justin J. , Buchman Vladimir L.
Published: December 2012

Synucleins are a family of homologous proteins principally known for their involvement in neurodegeneration. γ-Synuclein is highly expressed in human white adipose tissue and increased in obesity. Here we show that γ-synuclein is nutritionally regulated in white adipose tissue whereas its loss partially protects mice from high-fat diet (HFD)–induced obesity and ameliorates some of the associated metabolic complications. Compared with HFD-fed WT mice, HFD-fed γ-synuclein–null mutant mice display increased lipolysis, lipid oxidation, and energy expenditure, and reduced adipocyte hypertrophy. Knockdown of γ-synuclein in adipocytes causes redistribution of the key lipolytic enzyme ATGL to lipid droplets and increases lipolysis. γ-Synuclein–deficient adipocytes also contain fewer SNARE complexes of a type involved in lipid droplet fusion. We hypothesize that γ-synuclein may deliver SNAP-23 to the SNARE complexes under lipogenic conditions. Via these independent but complementary roles, γ-synuclein may coordinately modulate lipid storage by influencing lipolysis and lipid droplet formation. Our data reveal γ-synuclein as a regulator of lipid handling in adipocytes, the function of which is particularly important in conditions of nutrient excess.
Applications of science and engineering to quantify and control the
Deepwater Horizon
oil spill
Authors: McNutt Marcia K. , Chu Steven , Lubchenco Jane , Hunter Tom , Dreyfus Gabrielle , Murawski Steven A. , Kennedy David M.
Published: December 2012

The unprecedented engagement of scientists from government, academia, and industry enabled multiple unanticipated and unique problems to be addressed during the
Deepwater Horizon
oil spill. During the months between the initial blowout on April 20, 2010, and the final well kill on September 19, 2010, researchers prepared options, analyses of tradeoffs, assessments, and calculations of uncertainties associated with the flow rate of the well, well shut in, killing the well, and determination of the location of oil released into the environment. This information was used in near real time by the National Incident Commander and other government decision-makers. It increased transparency into BP’s proposed actions and gave the government confidence that, at each stage proposed, courses of action had been thoroughly vetted to reduce risk to human life and the environment and improve chances of success.
Neuregulin 1-HER axis as a key mediator of hyperglycemic memory effects in breast cancer
Authors: Park Jiyoung , Sarode Venetia R. , Euhus David , Kittler Ralf , Scherer Philipp E.
Published: December 2012

Poor outcomes in diabetic patients are observed across a range of human tumors, suggesting that cancer cells develop unique characteristics under diabetic conditions. Cancer cells exposed to hyperglycemic insults acquire permanent aggressive traits of tumor growth, even after a return to euglycemic conditions. Comparative genome-wide mapping of hyperglycemia-specific open chromatin regions and concomitant mRNA expression profiling revealed that the
neuregulin-1
gene, encoding an established endogenous ligand for the HER3 receptor, is activated through a putative distal enhancer. Our findings highlight the targeted inhibition of NRG1-HER3 pathways as a potential target for the treatment breast cancer patients with associated diabetes.
Direct and immune mediated antibody targeting of
ERBB
receptors in a colorectal cancer cell-line panel
Authors: Ashraf Shazad Q. , Nicholls Angela M. , Wilding Jennifer L. , Ntouroupi Triantafyllia G. , Mortensen Neil J. , Bodmer Walter F.
Published: December 2012

A significant proportion of colorectal cancer (CRC) patients are resistant to anti-ERBB1 [avian erythroblastic leukemia viral (v-erb-b) oncogene homolog, receptor for EGF] monoclonal antibodies (Mabs). We evaluated both immune and nonimmune effects of cetuximab (anti-ERBB1 Mab), trastuzumab (anti-ERBB2 Mab), pertuzumab (anti-ERBB2 Mab), and lapatinib (dual ERBB1 and ERBB2 tyrosine kinase inhibitor) in a large well-characterized panel of 64 CRC cell lines to find response predictive tumor characteristics. There was a significant correlation between the direct effects of cetuximab and lapatinib. Both agents were associated (
P
= 0.0004) with “triple’ wild-type status in
KRAS
,
BRAF
, and
PIK3CA
exon
20
. Most cell lines were resistant to the direct effects of anti-ERBB2 Mabs, suggesting that the effects of lapatinib might mainly be through ERBB1. Microarray mRNA expression profiles of sensitive and resistant cell lines showed that although ERBB1 receptor or ligand levels did not associate with cetuximab sensitivity, high levels of ERBB2 (
P
= 0.036) and amphiregulin (
P
= 0.026) predicted sensitivity to lapatinib. However, higher ERBB1 expression predicted susceptibility to cetuximab-induced antibody-dependent cellular cytotoxicity and occurred independently of
KRAS/BRAF/PIK3CA
mutations (
P
= 0.69). Lapatinib may be an effective alternative therapy to cetuximab in triple wild-type tumors. Microarray analysis provides suggestive biomarkers for resistance. ERBB1 levels, independent of mutation status, predict immune killing. Therefore, anti-ERBB1 antibodies may be considered in CRC tumors with higher ERBB1 expression and favorable FcγR polymorphisms.
Triassic leech cocoon from Antarctica contains fossil bell animal
Authors: Bomfleur Benjamin , Kerp Hans , Taylor Thomas N. , Moestrup Øjvind , Taylor Edith L.
Published: December 2012

Our understanding of the evolution of life on Earth is limited by the imperfection of the fossil record. One reason for this imperfect record is that organisms without hard parts, such as bones, shells, and wood, have a very low potential to enter the fossil record. Occasionally, however, exceptional fossil deposits that preserve soft-bodied organisms provide a rare glimpse of the true biodiversity during past periods of Earth history. We here present an extraordinary find of a fossil ciliate that is encased inside the wall layer of a more than 200 Ma leech cocoon from Antarctica. The microfossil consists of a helically contractile stalk that attaches to a main body with a peristomial feeding apparatus and a large C-shaped macronucleus. It agrees in every aspect with the living bell animals, such as
Vorticella
. Vorticellids and similar peritrichs are vital constituents of aquatic ecosystems worldwide, but so far have lacked any fossil record. This discovery offers a glimpse of ancient soft-bodied protozoan biotas, and also highlights the potential of clitellate cocoons as microscopic “conservation traps” comparable to amber.
Forward transport of proteins in the plasma membrane of migrating cerebellar granule cells
Authors: Wang Dong , She Liang , Sui Ya-nan , Yuan Xiao-bing , Wen Yunqing , Poo Mu-ming
Published: December 2012

Significance

Newly differentiated neurons migrate over long distances to reach their proper destination in the developing brain. The mechanisms by which neurons accomplish this translocation remain to be clarified. By analyzing the trajectories of antibody-coated single quantum dots bound to specific plasma membrane proteins, we found that membrane proteins of migrating cultured cerebellar granule cells exhibited net forward translocation in a form of biased drift, which is superimposed upon Brownian motion, and that this biased drift appears to be driven by myosin II-dependent active transport processes. Thus, plasma membrane proteins undergo forward translocation in unison with cytoplasmic components in migrating neurons.
Knowing versus producing
Authors: Keij Brigitta , Cornips Leonie , van Hout Roeland , Hulk Aafke , van Emmerik Joanne
Published: December 2012

Dutch nouns are divided into two groups according to grammatical gender which is, among others, marked on the definite determiner: common nouns take the definite determiner de and neuter nouns take the definite determiner het. This study is unique in systematically investigating the acquisition of grammatical gender and the definite determiner in the production and knowledge data of the same Dutch children. Three groups of children were examined: (i) typically developing monolinguals (L1-TD: 6;7—9;11), (ii) monolinguals with Specific Language Impairment (L1-SLI: 8;4-12;0), and (iii) typically developing bilinguals, who are early second language learners (eL2: 6;7-10;0). The three groups of children reveal different stages in discovering that de and het cover the gender paradigm. At comparable ages, the L1-TD children have completed this paradigm discovery; however, the eL2 children have not yet completed it, and the L1- SLI children are only at the first stage of the discovery of the gender paradigm.
Evaluating the Effects of Electricity on Fish Embryos as a Potential Strategy for Controlling Invasive Cyprinids
Authors: Nutile Sam , Amberg Jon J. , Goforth Reuben R.
Published: December 2012

Fish embryo responses to electricity have been evaluated to investigate impacts of electrofishing on survival of fish embryos. However, use of electricity as a lethal means of control for early life history stages of unwanted invasive fish species has not been investigated. We exposed Fathead Minnow Pimephales promelas and Zebrafish Danio rerio embryos at multiple developmental stages to voltage gradients between 2 and 24 V/cm with pulsed direct current (PDC) and virtual direct current (VDC) for 20 and 60 s. Goldfish Carassius auratus embryos were similarly exposed to the same voltage gradients, although these trials were limited to VDC for 60 s. Voltage gradients ≥20 V/cm resulted in significantly lower survival for Fathead Minnow and Zebrafish embryos, and Goldfish embryos exhibited significantly reduced survival at voltage gradients ≥16 V/cm. Zebrafish embryos also exhibited significantly lower survival with longer exposure duration and when exposed to VDC versus PDC, although Fathead Minnow embryo survival did not differ across exposure durations or current types. Based on these results, the use of electrical barriers to control bigheaded carps at early life history stages is likely impractical due to the large voltage gradients and high power densities necessary to transfer lethal power to embryos in open systems with ambient conductivities >300 μS/cm. The larger size of bigheaded carp eggs relative to those of our proxy cyprinids may make them more susceptible to lower voltage gradients. However, exploratory tests using a small number of wild‐caught bigheaded carp eggs suggested that voltage gradients and associated power densities needed to transfer lethal power to embryos under in situ ambient conductivities were similar to those required to reduce survival in the proxy fish, possibly due to the small size of the bigheaded carp embryos relative to the large void space in water‐hardened eggs.
Response of Wild Trout to Stream Restoration over Two Decades in the Blackfoot River Basin, Montana
Authors: Pierce Ron , Podner Craig , Carim Kellie
Published: December 2012

Anthropogenic degradation of aquatic habitats has prompted worldwide efforts to improve or restore stream habitats for fisheries. However, little information exists on the long‐term responses of salmonids to restoration in North American streams. To recover wild trout populations in the Blackfoot River in western Montana, a collaborative approach to stream restoration began in 1990 to improve degraded stream habitats, primarily on private land. To assess the efficacy of various restoration techniques (channel reconstruction and placement of instream habitat structures, restoration of natural instream flows, installation of fish ladders and screens at irrigation diversions, and modification of grazing practices) in the recovery of wild trout, we examined long‐term (>5 years) trends in trout abundance on 18 tributaries treated between 1990 and 2005 and subsequently monitored between 1989 and 2010. At pretreatment conditions, average trout abundance was significantly lower in treatment versus reference sites (0.19 versus 0.62 trout/m; P = 0.0001). By 3 years posttreatment, trout abundance had increased significantly to an average of 0.47 trout/m across treatment sites (P = 0.01) and was no longer significantly different from the reference average (P = 0.12). These initial rapid increases were sustained over the long term (5–21 years) in 15 streams. However, trout abundance declined below pretreatment levels on three streams presumably due to the return of human impacts from heavy riparian grazing and detrimental irrigation practices. Although long‐term (12 year) average response trends were positive, trends varied spatially and native trout responded more strongly in the upper portion of the basin. Study results indicate that restoration should focus in the mid to upper basin and emulate features of natural channels to promote life history diversity and the recovery of native trout. Finally, long‐term monitoring led to adaptive management on most (10 of 18) projects, and thus proved vital to the overall sustainability of wild trout fisheries throughout the basin.
Swordfish Vertical Distribution and Habitat Use in Relation to Diel and Lunar Cycles in the Western North Atlantic
Authors: Lerner Justin D. , Kerstetter David W. , Prince Eric D. , Talaue‐McManus Liana , Orbesen Eric S. , Mariano Arthur , Snodgrass Derke , Thomas Gary L.
Published: December 2012

The vertical movement patterns of eight Swordfish Xiphias gladius from 109‐ to 249‐cm lower jaw fork length in the western North Atlantic were studied utilizing pop‐up archival transmitting tags. Deployments ranged from 120 to 151 d. Swordfish demonstrated significant differences in depth and temperature distributions between daytime and nighttime periods. Individual Swordfish behavior was characterized by occupying surface waters of less than 100 m during the night and depths greater than 400 m during daytime hours, vertical movements between the surface and depth occurring during crepuscular hours. The maximum depth recorded was 1,448 m (one of the deepest recorded depths for the species). Daytime surfacing behavior was seen in all tagged Swordfish, a rare finding for Swordfish in tropical latitudes. A dominant diurnal period of 1 cycle/d was found from a power spectral density analysis of five of the tagged Swordfish, a novel method for determining periodicity in the behavior of tagged animals. Regression analysis indicated a significant positive relationship between depth and fraction of the moon illuminated, supporting anecdotal and vessel logbook information from local Swordfish fisheries indicating changes in depth in relation to lunar phase.
Connections between Campeche Bank and Red Snapper Populations in the Gulf of Mexico via Modeled Larval Transport
Authors: Johnson Donald R. , Perry Harriet M. , Lyczkowski‐Shultz Joanne
Published: December 2012

The potential for Red Snapper Lutjanus campechanus on Campeche Bank to contribute to regional fisheries in the Gulf of Mexico through larval transport was studied using numerical circulation model data. A tracking algorithm was applied at an array of starting locations over Campeche Bank and simulated larval propagules launched every 3 d during the spawning seasons of four model years within the period 2003–2010. Successful recruitment was defined as arrival in water depths less than 200 m after 31 d of planktonic drift, regional recruitment being defined as a percentage of propagules launched. It was found that successful natal retention to Campeche Bank was high, varying between 67% and 73% of all launched propagules. However, successful recruitment to other regions around the Gulf of Mexico (GOM) was sporadic and extremely low. Robustness of the methodology was examined in a set of experiments involving larval depth and subgrid scale diffusion. The results suggest that larvae from Campeche Bank can contribute to homogenization of the gene pool throughout the GOM but may be insufficient to restore depleted regional populations.
Exploring the Influence of Stock–Recruitment Relationships and Environmental Variables on Black Bass and Crappie Recruitment Dynamics in Missouri Reservoirs
Authors: Siepker Michael J. , Michaletz Paul H.
Published: December 2012

Large reservoirs provide important sport fisheries, but managing these fisheries is difficult because of the multiple biological and environmental variables that interact to shape them. Understanding how sport fish recruitment responds to parental stock and environmental influences would improve our management capabilities. We compiled long‐term datasets for 15 Missouri reservoirs and used them to examine the influence of parental stock abundance and a suite of environmental variables on the recruitment of Largemouth Bass Micropterus salmoides, Spotted Bass M. punctulatus, White Crappie Pomoxis annularis, and Black Crappie P. nigromaculatus. Comparisons of log‐linear, Ricker, and Beverton–Holt stock–recruit models revealed that the log‐linear model was the most parsimonious for Largemouth Bass, White Crappie, and Black Crappie, but the Ricker model was best for Spotted Bass. However, stock–recruit models alone explained less than 13% of the variation in Largemouth Bass, Spotted Bass, and White Crappie recruitment while explaining about 33% of the variability in recruitment of Black Crappie. Largemouth Bass recruitment was positively related to spring rises in water levels, summer water levels, and average summer air temperatures, whereas Spotted Bass recruitment was positively related to spring air temperatures. White Crappie recruitment was positively related to total phosphorus levels and drops in spring water levels. Black Crappie recruitment was best explained by the model positively relating recruitment to spawning stock abundance, spring water levels, and summer water levels, while negatively relating recruitment to rapid drops in spring water levels. With the exception of models for Black Crappie, the best models did not include spawning stock abundance, and environmental variables appeared more important in explaining variation in recruitment. However, environmental variables in these models explained only a modest amount of variation (27–44%) in recruitment, revealing the complexity of recruitment processes in large reservoirs.
The effect of scene structure on time perception
Authors: Alexander Varakin D. , Klemes Keith J. , Porter Kennetha A.
Published: December 2012

The current experiments examined the hypothesis that scene structure affects time perception. In three experiments, participants judged the duration of realistic scenes that were presented in a normal or jumbled (i.e., incoherent) format. Experiment 1 demonstrated that the subjective duration of normal scenes was greater than subjective duration of jumbled scenes. In Experiment 2, gridlines were added to both normal and jumbled scenes to control for the number of line terminators, and scene structure had no effect. In Experiment 3, participants performed a secondary task that required paying attention to scene structure, and scene structure's effect on duration judgements reemerged. These findings are consistent with the idea that perceived duration can depend on visual–cognitive processing, which in turn depends on both the nature of the stimulus and the goals of the observer.
The insignificance of major mergers in driving star formation at z ≃ 2
Authors: Kaviraj S. , Cohen S. , Windhorst R. A. , Silk J. , O'Connell R. W. , Dopita M. A. , Dekel A. , Hathi N. P. , Straughn A. , Rutkowski M.
Published: December 2012

We study the significance of major-merger-driven star formation in the early Universe, by quantifying the contribution of this process to the total star formation budget in 80 massive (M* > 1010 M⊙) galaxies at z ≃ 2. Employing visually classified morphologies from rest-frame V-band Hubble Space Telescope (HST) imaging, we find that 55±14 per cent of the star formation budget is hosted by non-interacting late types, with 27±8 per cent in major mergers and 18±6 per cent in spheroids. Given that a system undergoing a major merger continues to experience star formation driven by other processes at this epoch (e.g. cold accretion and minor mergers), ∼27 per cent is an upper limit to the major-merger contribution to star formation activity at this epoch. The ratio of the average specific star formation rate in major mergers to that in the non-interacting late types is ∼2.2:1, suggesting that the enhancement of star formation due to major merging is typically modest, and that just under half the star formation in systems experiencing major mergers is unrelated to the merger itself. Taking this into account, we estimate that the actual major-merger contribution to the star formation budget may be as low as ∼15 per cent. While our study does not preclude a major-merger-dominated era in the very early Universe, if the major-merger contribution to star formation does not evolve strongly into larger look-back times, then this process has a relatively insignificant role in driving stellar mass assembly over cosmic time.
Giant stellar arcs in the Large Magellanic Cloud: a possible link with past activity of the Milky Way nucleus
Authors: Efremov Yuri N.
Published: December 2012

The origin of the giant stellar arcs in the Large Magellanic Cloud (LMC) remains a controversial issue, one that has been discussed since 1966. No other star/cluster arc is so perfect a segment of a circle; moreover, there is another similar arc nearby. Many hypotheses were advanced to explain these arcs and all but one of these was disproved. It was proposed in 2004 that the origin of these arcs was a bow shock from the jet that is intermittently fired by the Milky Way nucleus; during its last episode of activity the jet was pointed toward the LMC. Quite recently, evidence for such a jet indeed appeared. We suggest that it was once energetic enough to trigger star formation in the LMC, and if the jet opening angle was about 2° then it could push out H i gas from a region of about 2 kpc in size, forming a cavity LMC4, but also squeeze two dense clouds that occurred in the same area, causing the formation of stars along their surfaces facing the core of the Milky Way. As a result, spherical segments of stellar shells might arise, visible now as the arcs named the Quadrant and Sextant, the apexes of which point towards the centre of the Milky Way. The orientation of both arcs could be the key to unlocking their origin. Here we give data that confirm the above hypothesis, amongst which are the radial velocities of stars inside and outside the larger of the LMC arcs. The probability is low that a jet from an active galactic nucleus (AGN) points towards a nearby galaxy and triggers star formation there, but a few other examples are now known or suspected.