bluuebunny/crossref_metadata_2025 huggingface dataset:
Entwicklung und Validierung eines Fragebogens zur emotionsspezifischen Selbsteinschätzung emotionaler Kompetenzen (SEK-ES)
Authors: Ebert David Daniel , Christ Oliver , Berking Matthias
Published: March 2013

Zahlreiche Studien belegen die Relevanz von Emotionsregulationskompetenzen für die psychische Gesundheit. Problematisch ist jedoch, dass viele dieser Studien Selbsteinschätzungsmaße verwenden, die Kompetenzen im Umgang mit Emotionen oder Stimmungen im Allgemeinen zu erfassen suchen. Dadurch bleibt unklar, auf welche Emotionen sich die Probanden beim Ausfüllen beziehen und inwieweit Bewältigungskompetenzen über verschiedene Emotionen hinweg differieren. Ziel der Studie ist daher die Entwicklung und Validierung eines Fragebogens zur ökonomischen Selbsteinschätzung von sowohl emotionsübergreifenden als auch emotionsspezifischen Bewältigungskompetenzen. Auf Basis des emotionsunspezifischen SEK-27 ( Berking & Znoj, 2008 ) wurde ein Fragebogen zur emotionsspezifischen Selbsteinschätzung des konstruktiven Umgangs mit Stress, Angst, Ärger, Traurigkeit und depressiver Stimmung entwickelt (SEK-ES). Mit Hilfe einer nicht-klinischen (N = 358) und einer klinischen Stichprobe (N = 579) wurden Itemkennwerte, Reliabilität, Validität sowie Veränderungssensitivität des SEK-ES bestimmt. Die Befunde sprechen für gute bis sehr gute psychometrische Eigenschaften des Instrumentes und für die Notwendigkeit, emotionale Kompetenzen emotionsspezifisch zu erfassen.
Point-contact Andreev-reflection spectroscopy in anisotropic superconductors: The importance of directionality (Review Article)
Authors: Daghero D. , Tortello M. , Pecchio P. , Stepanov V. A. , Gonnelli R. S.
Published: March 2013

Point-contact Andreev-reflection spectroscopy (PCARS) has demonstrated to be one of the most effective experimental tools for the investigation of fundamental properties of superconductors such as the superconducting gap and the electron–phonon (or, more generally, electron–boson) coupling. By reviewing relevant examples reported in literature and presenting new results, in this paper we show that when the direction of the interface with respect to the crystallographic axes can be controlled (as in single crystals and epitaxial films) PCARS can provide invaluable information about the anisotropy of the pairing wavefunction or—in the case of multiband superconductors—on the number, amplitude and symmetry of the energy gaps. Moreover, the analysis of PCARS results within a suitable 3D generalization of the BTK model allows obtaining qualitative information about the topology of the Fermi surface.
Emerging evidence for FFLO states in layered organic superconductors (Review Article)
Authors: Beyer R. , Wosnitza J.
Published: March 2013

In this short review, we report on the recently found growing experimental evidence for the existence of Fulde–Ferrell–Larkin–Ovchinnikov (FFLO) states in quasi-two-dimensional organic superconductors. At high magnetic fields aligned parallel to the conducting organic layers, we observe an upturn of the upper critical field beyond the Pauli limit, as evidenced by specific-heat and torque-magnetization measurements. Inside the superconducting state a second thermodynamic transition emerges. These features appear only in a very narrow angular region close to parallel-field orientation.
Electron tunneling into surface states through an inhomogeneous barrier: Asymptotically exact solution of the problem, and STM theory
Authors: Khotkevych N. V. , Kolesnichenko Yu. A. , van Ruitenbeek J. M.
Published: March 2013

We have found an asymptotically exact solution of the Schrödinger equation for electrons tunneling into surface states through an inhomogeneous barrier of large amplitude. Assuming an elliptic dispersion law for the charge carriers, the “standing wave” pattern in the conductance of the system resulting from the electron scattering by a single defect in the vicinity of the surface is analyzed.
Current-field diagram for the magnetic states of a surface spin valve in a point contact with a single ferromagnetic film
Authors: Yanson I. K. , Balkashin O. P. , Fisun V. V. , Yanson Yu. I. , Naidyuk Yu. G.
Published: March 2013

This is a study of the influence of an external magnetic field H and an electric current I on the spin-valve (SV) effect in a point contact between a ferromagnetic thin film (F) and a sharp, nonmagnetic metal tip (N). To explain our observations, we propose a model for a local surface SV in an N/F contact of this type. In this model, a ferromagnetic cluster at the N/F interface serves as the free layer in the SV. This cluster has a larger coercive field than the bulk of the ferromagnetic film, presumably due to its nanoscale nature. Finally, we construct a magnetic state diagram of the surface SV as a function of I and H.
Low-dimensional dynamical system for Rayleigh-Bénard convection subjected to magnetic field
Authors: Gotoda Hiroshi , Takeuchi Riyota , Okuno Yuta , Miyano Takaya
Published: March 2013

We have numerically investigated the dynamical behavior of Rayleigh-Bénard (RB) convection in an incompressible conducting fluid subjected to a magnetic field by solving a low-dimensional dynamical system. Its dynamical properties are quantified by nonlinear time series analysis based on chaos theory. The stretching and folding in the phase space for the chaos region (normalized Rayleigh number r = 28) and the intermittent chaos region (r = 166.1) of RB convection at a high magnetic Prandtl number of Pm = 10 become complex with increasing applied magnetic field, and the degeneration of chaos is induced by the limit of the strong magnetic field owing to the overwhelming Lorentz force compared with the buoyancy. The results obtained in this study show the importance of the magnetic Prandtl number to the dynamical behavior of RB convection subjected to a magnetic field.
The ferroelectricity of Bi0.9Pb0.1FeO3 films grown on atomic flat SrRuO3/SrTiO3 substrates
Authors: Chou H. , Liu K. C. , Wu C. T. , Wu C. P. , Bohra M. , Pyatakov A. , Chen Y. C. , Yu C. C. , Sun S. J.
Published: March 2013

Bi0.9Pb0.1FeO3 (BPFO) films were grown on SrRuO3 (SRO)/SrTiO3 (STO) substrates. The surface morphology of BPFO films is highly dependent on that of the SRO layer. Though the step height of STO (100) substrate is equal to one unit cell of STO crystal, the height and width of steps on the surface of SRO and BPFO are larger, which supports a step bunching growth mode on both the SRO layer and BPFO films. At zero bias voltage, the BPFO film exhibits a natural dipole polarization toward the SRO layer, which is believed to be due to the negative charge accumulation at the BPFO/SRO interface, and manifests of 71° and 109° but 180° domain walls. Doping of Pb distorted the BPFO crystal lattice to near cubic that weakens the electric anisotropy and forms a two-step flipping process. To complete a 180° dipole flipping procedure, the dipole moment first rotates 71° to adjacent states followed by a 109° rotation to the final 180° state.
Environmental decoherence stabilizes quantum-dot cellular automata
Authors: Blair Enrique P. , Lent Craig S.
Published: March 2013

We consider the effects of interaction with the environment on decoherence in quantum-dot cellular automata (QCA). We model the environment as a Coulombically interacting random assembly of quantum double-dots. The time evolution of our model system + environment is unitary and maintains one coherent state. We explicitly calculate the reduced density operators for the system and for the environment from the full coherent state. From the reduced density matrix of the system, we calculate the coherence vector and the Von Neumann entropy. The entanglement of system and environmental degrees of freedom lead to decoherence, which drives the system into the Zurek pointer states. The quantum information lost by the system, quantified by the entropy, is present in the quantum mutual information between the system and the environment. We explore the competition between environmental decoherence and system dynamics. For even a modest environmental interaction, the pointer states are the QCA information-bearing degrees of freedom, so that environmental decoherence, while destructive of quantum information, tends to stabilize QCA bit information.
Quantitative isolation of band-gap formation mechanisms by randomizing the lattice arrangement in photonic crystals
Authors: Nojima S. , Kaneda G. , Aizawa K.
Published: March 2013

The band-gap formation mechanisms for photonic crystals (PCs) have been theoretically investigated on the basis of the analogy of the band gap to that for the semiconductors. On the reasonable assumption that the photonic band-gaps are created through both or either of the Bragg and the Mie processes, we attempted to quantitatively determine which process is more responsible for the band-gap formation. To achieve this purpose, we introduced the randomness of the lattice arrangement into the PCs. Through the analysis of the band-gap shrinkage as a function of the randomness, we have succeeded for the first time in quantitatively isolating the gap formation mechanisms in the dielectric PCs. From these results, we further conclude that the dielectric PCs have a greater tolerance than the metallic PCs for the fluctuation of the lattice arrangements, which would undoubtedly facilitate the fabrication of the crystals.
Study of hyperfine interactions in GdIn3
Authors: Cabrera-Pasca G. A. , Mestnik-Filho J. , Carbonari A. W. , Saxena R. N.
Published: March 2013

In the present work, an experimental and theoretical study of the hyperfine interactions at Gd and In sites in GdIn3 were performed. The experimental measurements were carried out by perturbed angular correlation spectroscopy using 140Ce and 111Cd nuclear probes substituting Gd and In sites, respectively. Results for 111Cd probe at In sites in GdIn3 revealed only electric quadrupole interactions, differently from the results for CeIn3 where, in addition to quadrupole interactions, a magnetic hyperfine field (Bhf) was also observed at In sites. The temperature dependence of Bhf at 140Ce on Gd sites in GdIn3 could be fitted by a Brillouin curve, and the extrapolated Bhf value to 0 K was found to be much smaller than that at 140Ce in CeIn3. Ab-initio electronic structure calculations for GdIn3 matrix doped with Ce were confronted with experimental data in order to explain such differences. The calculations were carried out within density functional theory using Augmented Plane Waves plus local orbitals basis functions as embodied in the wien2k package and with the GGA + U approximation. The value for the Hubbard U parameter was determined for each case. Results of the calculations show that the absence of Bhf in Cd probes in GdIn3 is related with the orientation of the magnetic moments in (001) direction, whereas in CeIn3 the magnetic moments are oriented out of this direction.
Characterizing epoxy composites filled with carbonaceous nanoparticles from dc to microwave
Authors: Bychanok D. , Kuzhir P. , Maksimenko S. , Bellucci S. , Brosseau C.
Published: March 2013

We have used several methods to measure the effective complex permittivity of epoxy composites filled with carbonaceous (carbon black, single-walled carbon nanotube, and multi-walled carbon nanotube) over nine decades of frequency. The composite samples were fabricated by shear mixing. The spectral analysis of permittivity of these nanocomposites is in good agreement with Jonscher's modelling. We point out, taking these examples, that the experimental frequency dependence of the effective permittivity has a range of interesting properties. The likely transport mechanisms responsible for the dielectric relaxation in these samples can be modelled by the dipolar relaxation and anomalous low-frequency dispersion below and above percolation, respectively.
Solving power system unit commitment with wind farms using multi-objective quantum-inspired binary particle swarm optimization
Authors: Wu Xiaoshan , Zhang Buhan , Li Junfang , Luo Gang , Duan Yao , Wang Kui
Published: March 2013

To reduce air pollutant emissions, it is essential to develop energy-saving and emission-reducing in power generation scheduling. A double-objective function considering both costs and emissions is proposed, and to consider the randomness and uncontrollability of wind power, interval forecasting information of wind power with a certain probability is used to determine the required spinning reserve capacity. Simultaneously, the paper presents a new method to solve it. The proposed method uses a new Multi-objective Quantum-inspired Binary particle swarm optimization (QBPSO) for the unit on/off problem and the primal-dual interior point method for load economic dispatch problem. Based on the QBPSO, the article introduces the Pareto optimal concept and the external archive to it. The paper also adopts the heuristic adjusted regulations to ensure the whole algorithm to search the optimal particle in the feasible region. The proposed method is applied to power systems which are composed of 10-units with 24-h demand horizon and a certain proportion of wind farms. The simulation results prove the validity of the model and algorithm.
How does buoyancy of hydrogel microrobots affect their magnetic propulsion in liquids?
Authors: Palagi Stefano , Mazzolai Barbara , Innocenti Claudia , Sangregorio Claudio , Beccai Lucia
Published: March 2013

Gravity compensation is a key requirement for achieving three-dimensional navigation of magnetic microrobots in fluids. Here we present a brief theoretical introduction to the issue of gravity compensation in the case of magnetic “pulling” propulsion, explicitly highlighting the constraints it introduces. Therefore, we evaluate the advantages that quasi-neutral buoyancy gives to hydrogel microrobots, demonstrating that despite their relatively weak magnetic properties, for certain size/velocity ranges they could be more easily and efficiently propelled than state-of-the-art metal microrobots. Hence, our analysis endorses the adoption of smart polymers, such as stimuli-responsive hydrogels, for developing truly multifunctional magnetic microrobots.
Effect of charge compensation on the photoelectrochemical properties of Ho-doped SrTiO3 films
Authors: Zhao Long , Fang Liang , Dong Wen , Zheng Fengang , Shen Mingrong , Wu Tom
Published: March 2013

When Ho3+ ions are substituted at Sr2+ sites in SrTiO3 (STO), the excess positive charges are compensated via three complementary routes: (1) strontium vacancies, (2) titanium vacancies, and (3) conduction electrons. In this study, we show that the photoelectrochemical properties of Ho-doped STO films are dependent on the charge compensation mechanisms. The compensation mechanism via the titanium vacancies exhibits the highest photocurrent density, which is 1.7 times higher than that of the pure STO sample. Based on the measured dielectric properties and electrochemical impedance spectroscopy data, we propose that the enhanced dielectric constant of the films can enlarge the width of the space charge region at the film/liquid interface, which eventually leads to the increase of the photocurrent density. Further enhancement of photocurrent density is obtained in the samples decorated with appropriate amounts of Pt nanoparticles, showing the advantage of composites for achieving the efficient photoelectrochemical property.
The A-site Li+ driven orthorhombic-tetragonal ferroelectric phase transition and evolving local structures in (Na,K)(Nb,Sb)O3-LiTaO3 lead-free ceramics
Authors: Fu Jian , Zuo Ruzhong
Published: March 2013

Synchrotron x-ray diffraction and absorption fine structure and Raman spectra on (Na,K)(Nb,Sb)O3-LiTaO3 ceramics suggested that the compositionally induced orthorhombic to tetragonal (O-T) ferroelectric phase transition is dominantly driven by A-site Li+ ions with a large [001] off centering, while B-site Nb atoms are only localized near their average positions of the NbO6 octahedra between O and T phases. The Nb-O octahedra distort over the phase transition by adjusting their positions and orientations. The continuous change of lattice constants bo and at across the phase boundary would facilitate the O-T phase transition through a jump of polar axis from pseudocubic [101] to [001].
Suppression of thermal conductivity in InxGa1−xN alloys by nanometer-scale disorder
Authors: Tong T. , Fu D. , Levander A. X. , Schaff W. J. , Pantha B. N. , Lu N. , Liu B. , Ferguson I. , Zhang R. , Lin J. Y. , Jiang H. X. , Wu J. , Cahill David G.
Published: March 2013

We have systematically measured the room-temperature thermal conductivity of epitaxial layers of InxGa1−xN alloys with 15 different Indium compositions ranging from 0.08 to 0.98 by time-domain thermoreflectance method. The data are compared to the estimates of the strength of phonon scattering by cation disorder. The thermal conductivity is in good agreement with the theoretical modeling results based on the mass difference for In-rich (x > 0.9) and Ga-rich (x < 0.2) compositions. At intermediate compositions (0.2 < x < 0.9), the thermal conductivity is strongly suppressed below the values expected for homogeneous alloys. We attribute this suppression of thermal conductivity to phonon scattering by nanometer-scale compositional inhomogeneities in alloys.
Hunger-promoting hypothalamic neurons modulate effector and regulatory T-cell responses
Authors: Matarese Giuseppe , Procaccini Claudio , Menale Ciro , Kim Jae Geun , Kim Jung Dae , Diano Sabrina , Diano Nadia , De Rosa Veronica , Dietrich Marcelo O. , Horvath Tamas L.
Published: March 2013

Whole-body energy metabolism is regulated by the hypothalamus and has an impact on diverse tissue functions. Here we show that selective knockdown of Sirtuin 1 Sirt1 in hypothalamic Agouti-related peptide-expressing neurons, which renders these cells less responsive to cues of low energy availability, significantly promotes CD4+T-cell activation by increasing production of T helper 1 and 17 proinflammatory cytokines via mediation of the sympathetic nervous system. These phenomena were associated with an impaired thymic generation of forkhead box P3 (FoxP3+) naturally occurring regulatory T cells and their reduced suppressive capacity in the periphery, which resulted in increased delayed-type hypersensitivity responses and autoimmune disease susceptibility in mice. These observations unmask a previously unsuspected role of hypothalamic feeding circuits in the regulation of adaptive immune response.
Aye-aye population genomic analyses highlight an important center of endemism in northern Madagascar
Authors: Perry George H. , Louis Edward E. , Ratan Aakrosh , Bedoya-Reina Oscar C. , Burhans Richard C. , Lei Runhua , Johnson Steig E. , Schuster Stephan C. , Miller Webb
Published: March 2013

We performed a population genomics study of the aye-aye, a highly specialized nocturnal lemur from Madagascar. Aye-ayes have low population densities and extensive range requirements that could make this flagship species particularly susceptible to extinction. Therefore, knowledge of genetic diversity and differentiation among aye-aye populations is critical for conservation planning. Such information may also advance our general understanding of Malagasy biogeography, as aye-ayes have the largest species distribution of any lemur. We generated and analyzed whole-genome sequence data for 12 aye-ayes from three regions of Madagascar (North, West, and East). We found that the North population is genetically distinct, with strong differentiation from other aye-ayes over relatively short geographic distances. For comparison, the average
F
ST
value between the North and East aye-aye populations—separated by only 248 km—is over 2.1-times greater than that observed between human Africans and Europeans. This finding is consistent with prior watershed- and climate-based hypotheses of a center of endemism in northern Madagascar. Taken together, these results suggest a strong and long-term biogeographical barrier to gene flow. Thus, the specific attention that should be directed toward preserving large, contiguous aye-aye habitats in northern Madagascar may also benefit the conservation of other distinct taxonomic units. To help facilitate future ecological- and conservation-motivated population genomic analyses by noncomputational biologists, the analytical toolkit used in this study is available on the Galaxy Web site.
Dense colloidal fluids form denser amorphous sediments
Authors: Liber Shir R. , Borohovich Shai , Butenko Alexander V. , Schofield Andrew B. , Sloutskin Eli
Published: March 2013

We relate, by simple analytical centrifugation experiments, the density of colloidal fluids with the nature of their randomly packed solid sediments. We demonstrate that the most dilute fluids of colloidal hard spheres form loosely packed sediments, where the volume fraction of the particles approaches in frictional systems the random loose packing limit,
φ

RLP

= 0.55. The dense fluids of the same spheres form denser sediments, approaching the so-called random close packing limit,
φ

RCP

= 0.64. Our experiments, where particle sedimentation in a centrifuge is sufficiently rapid to avoid crystallization, demonstrate that the density of the sediments varies monotonically with the volume fraction of the initial suspension. We reproduce our experimental data by simple computer simulations, where structural reorganizations are prohibited, such that the rate of sedimentation is irrelevant. This suggests that in colloidal systems, where viscous forces dominate, the structure of randomly close-packed and randomly loose-packed sediments is determined by the well-known structure of the initial fluids of simple hard spheres, provided that the crystallization is fully suppressed.
Genomic assay reveals tolerance of DNA damage by both translesion DNA synthesis and homology-dependent repair in mammalian cells
Authors: Izhar Lior , Ziv Omer , Cohen Isadora S. , Geacintov Nicholas E. , Livneh Zvi
Published: March 2013

DNA lesions can block replication forks and lead to the formation of single-stranded gaps. These replication complications are mitigated by DNA damage tolerance mechanisms, which prevent deleterious outcomes such as cell death, genomic instability, and carcinogenesis. The two main tolerance strategies are translesion DNA synthesis (TLS), in which low-fidelity DNA polymerases bypass the blocking lesion, and homology-dependent repair (HDR; postreplication repair), which is based on the homologous sister chromatid. Here we describe a unique high-resolution method for the simultaneous analysis of TLS and HDR across defined DNA lesions in mammalian genomes. The method is based on insertion of plasmids carrying defined site-specific DNA lesions into mammalian chromosomes, using phage integrase-mediated integration. Using this method we show that mammalian cells use HDR to tolerate DNA damage in their genome. Moreover, analysis of the tolerance of the UV light-induced 6–4 photoproduct, the tobacco smoke-induced benzo[
a
]pyrene-guanine adduct, and an artificial trimethylene insert shows that each of these three lesions is tolerated by both TLS and HDR. We also determined the specificity of nucleotide insertion opposite these lesions during TLS in human genomes. This unique method will be useful in elucidating the mechanism of DNA damage tolerance in mammalian chromosomes and their connection to pathological processes such as carcinogenesis.
Glutamate receptor desensitization is mediated by changes in quaternary structure of the ligand binding domain
Authors: Schauder David M. , Kuybeda Oleg , Zhang Jinjin , Klymko Katherine , Bartesaghi Alberto , Borgnia Mario J. , Mayer Mark L. , Subramaniam Sriram
Published: March 2013

Glutamate receptor ion channels are membrane proteins that mediate excitatory synaptic transmission in the central nervous system of vertebrates. Insight into molecular mechanisms underlying glutamate receptor gating is limited by lack of structural information for receptors trapped in different conformational states. Here, we report the use of single-particle cryoelectron tomography to determine the structures, at ∼21 Å resolution, of full-length GluK2 kainate receptors trapped in antagonist-bound resting and agonist-bound desensitized states. The resting state, stabilized by the competitive antagonist LY466195, closely resembles the crystal structure of the AMPA receptor GluA2, with well-resolved proximal and distal subunits exhibiting cross-over between the twofold symmetric amino terminal domain and a twofold symmetric ligand binding domain (LBD) dimer of dimers assembly. In the desensitized state, the LBD undergoes a major rearrangement, resulting in a separation of the four subunits by ∼25 Å. However, the amino terminal domain, transmembrane, and cytoplasmic regions of the receptor have similar conformations in the resting and desensitized states. The LBD rearrangement was not anticipated in prior models based on crystal structures for soluble LBD dimer assemblies, and we speculate that subunit separation allows a better match to the fourfold symmetric ion channel domain. From fits of the amino terminal domain and LBD domains into the density map of the desensitized state we have derived a structural model for differences in quaternary conformation between the resting and desensitized states.
Achieving the triple bottom line in the face of inherent trade-offs among social equity, economic return, and conservation
Authors: Halpern Benjamin S. , Klein Carissa J. , Brown Christopher J. , Beger Maria , Grantham Hedley S. , Mangubhai Sangeeta , Ruckelshaus Mary , Tulloch Vivitskaia J. , Watts Matt , White Crow , Possingham Hugh P.
Published: March 2013

Triple–bottom-line outcomes from resource management and conservation, where conservation goals and equity in social outcomes are maximized while overall costs are minimized, remain a highly sought-after ideal. However, despite widespread recognition of the importance that equitable distribution of benefits or costs across society can play in conservation success, little formal theory exists for how to explicitly incorporate equity into conservation planning and prioritization. Here, we develop that theory and implement it for three very different case studies in California (United States), Raja Ampat (Indonesia), and the wider Coral Triangle region (Southeast Asia). We show that equity tends to trade off nonlinearly with the potential to achieve conservation objectives, such that similar conservation outcomes can be possible with greater equity, to a point. However, these case studies also produce a range of trade-off typologies between equity and conservation, depending on how one defines and measures social equity, including direct (linear) and no trade-off. Important gaps remain in our understanding, most notably how equity influences probability of conservation success, in turn affecting the actual ability to achieve conservation objectives. Results here provide an important foundation for moving the science and practice of conservation planning—and broader spatial planning in general—toward more consistently achieving efficient, equitable, and effective outcomes.
Universal distribution of component frequencies in biological and technological systems
Authors: Pang Tin Yau , Maslov Sergei
Published: March 2013

Bacterial genomes and large-scale computer software projects both consist of a large number of components (genes or software packages) connected via a network of mutual dependencies. Components can be easily added or removed from individual systems, and their use frequencies vary over many orders of magnitude. We study this frequency distribution in genomes of ∼500 bacterial species and in over 2 million Linux computers and find that in both cases it is described by the same scale-free power-law distribution with an additional peak near the tail of the distribution corresponding to nearly universal components. We argue that the existence of a power law distribution of frequencies of components is a general property of any modular system with a multilayered dependency network. We demonstrate that the frequency of a component is positively correlated with its dependency degree given by the total number of upstream components whose operation directly or indirectly depends on the selected component. The observed frequency/dependency degree distributions are reproduced in a simple mathematically tractable model introduced and analyzed in this study.
Phosphatidylinositol 5-phosphate 4-kinase (PIP4K) regulates TOR signaling and cell growth during
Drosophila
development
Authors: Gupta Amit , Toscano Sarah , Trivedi Deepti , Jones David R. , Mathre Swarna , Clarke Jonathan H. , Divecha Nullin , Raghu Padinjat
Published: March 2013

During development,
Drosophila
larvae undergo a dramatic increase in body mass wherein nutritional and developmental cues are transduced into growth through the activity of complex signaling pathways. Class I phosphoinositide 3-kinases have an established role in this process. In this study we identify
Drosophila
phosphatidylinositol 5-phosphate 4-kinase (dPIP4K) as a phosphoinositide kinase that regulates growth during larval development. Loss-of-function mutants in dPIP4K show reduced body weight and prolonged larval development, whereas overexpression of dPIP4K results both in an increase in body weight and shortening of larval development. The growth defect associated with dPIP4K loss of function is accompanied by a reduction in the average cell size of larval endoreplicative tissues. Our findings reveal that these phenotypes are underpinned by changes in the signaling input into the target of rapamycin (TOR) signaling complex and changes in the activity of its direct downstream target p70 S6 kinase. Together, these results define dPIP4K activity as a regulator of cell growth and TOR signaling during larval development.
Targeting chronic lymphocytic leukemia cells with a humanized monoclonal antibody specific for CD44
Authors: Zhang Suping , Wu Christina C. N. , Fecteau Jessie-F. , Cui Bing , Chen Liguang , Zhang Ling , Wu Rongrong , Rassenti Laura , Lao Fitzgerald , Weigand Stefan , Kipps Thomas J.
Published: March 2013

Chronic lymphocytic leukemia (CLL) cells express high levels of CD44, a cell-surface glycoprotein receptor for hyaluronic acid. We found that a humanized mAb specific for CD44 (RG7356) was directly cytotoxic for leukemia B cells, but had little effect on normal B cells. Moreover, RG7356 could induce CLL cells that expressed the zeta-associated protein of 70 kDa (ZAP-70) to undergo caspase-dependent apoptosis, independent of complement or cytotoxic effector cells. The cytotoxic effect of this mAb was not mitigated when the CLL cells were cocultured with mesenchymal stromal cells (MSCs) or hyaluronic acid or when they were stimulated via ligation of the B-cell receptor with anti-µ. RG7356 induced rapid internalization of CD44 on CLL cells at 37 °C, resulting in reduced expression of ZAP-70, which we found was complexed with CD44. Administration of this mAb at a concentration of 1 mg/kg to immune-deficient mice engrafted with human CLL cells resulted in complete clearance of engrafted leukemia cells. These studies indicate that this mAb might have therapeutic activity, particularly in patients with CLL that express ZAP-70.
Viral infection modulation and neutralization by camelid nanobodies
Authors: Desmyter Aline , Farenc Carine , Mahony Jennifer , Spinelli Silvia , Bebeacua Cecilia , Blangy Stéphanie , Veesler David , van Sinderen Douwe , Cambillau Christian
Published: March 2013

Significance

Lactococcal siphophages infectLactococcus lactis, a Gram-positive bacterium used in commercial dairy fermentations. The phage TP901-1 baseplate (BP) recognizes and binds specifically to polysaccharides covering the host cell. We raised llama nanobodies against the BP as tools to dissect the molecular determinants of phage infection. Using complementary techniques, we identified BP binders and determined their affinity and epitopes for their targets and their impact on phage infectivity. X-ray structures revealed that two nanobodies block the BP saccharide binding site, and viral infection assays showed that they neutralize infection, a possible way to circumvent phages detrimental effect on dairy fermentation.
Substrate selectivity in glutamate-dependent acid resistance in enteric bacteria
Authors: Tsai Ming-Feng , McCarthy Patrick , Miller Christopher
Published: March 2013

The bacterial antiporter GadC plays a central role in the glutamate (Glu)-dependent acid resistance system, which protects enteric bacteria against the extreme acidity of the human stomach. Upon acid shock, GadC imports Glu into the cytoplasm, where Glu decarboxylases consume a cytoplasmic proton, which ends up as a “virtual” proton in the decarboxylated product γ-aminobutyric acid (GABA) and is then exported via GadC. It was therefore proposed that GadC counters intracellular acidification by continually pumping out virtual protons. This scenario, however, is oversimplified. In gastric environments, GadC encounters substrates in multiple carboxyl protonation forms (outside: Glu
−
, Glu
0
, Glu
+
; inside: GABA
0
, GABA
+
). Of the six possible combinations of antiport partners, Glu
+
/GABA
0
results in proton influx, Glu
0
/GABA
0
and Glu
+
/GABA
+
are proton neutral, and Glu
−
/GABA
0
, Glu
−
/GABA
+
, or Glu
0
/GABA
+
lead to proton extrusion. Which of these exchanges does GadC catalyze? To attack this problem, we developed an oriented GadC liposome system holding a three-unit inward pH gradient to mimic the conditions facing bacteria in the stomach. By assessing the electrogenicity of substrate transport, we demonstrate that GadC selectively exchanges Glu
−
or Glu
0
with GABA
+
, resulting in effective proton extrusion of >0.9 H
+
per turnover to counter proton invasion into acid-challenged bacteria. We further show that GadC selects among protonated substrates using a charge-based mechanism, rather than directly recognizing the protonation status of the carboxyl groups. This result paves the way for future work to identify the molecular basis of GadC’s substrate selectivity.
Decreased water flowing from a forest amended with calcium silicate
Authors: Green Mark B. , Bailey Amey S. , Bailey Scott W. , Battles John J. , Campbell John L. , Driscoll Charles T. , Fahey Timothy J. , Lepine Lucie C. , Likens Gene E. , Ollinger Scott V. , Schaberg Paul G.
Published: March 2013

Acid deposition during the 20th century caused widespread depletion of available soil calcium (Ca) throughout much of the industrialized world. To better understand how forest ecosystems respond to changes in a component of acidification stress, an 11.8-ha watershed was amended with wollastonite, a calcium silicate mineral, to restore available soil Ca to preindustrial levels through natural weathering. An unexpected outcome of the Ca amendment was a change in watershed hydrology; annual evapotranspiration increased by 25%, 18%, and 19%, respectively, for the 3 y following treatment before returning to pretreatment levels. During this period, the watershed retained Ca from the wollastonite, indicating a watershed-scale fertilization effect on transpiration. That response is unique in being a measured manipulation of watershed runoff attributable to fertilization, a response of similar magnitude to effects of deforestation. Our results suggest that past and future changes in available soil Ca concentrations have important and previously unrecognized implications for the water cycle.
Oncogenic RAS pathway activation promotes resistance to anti-VEGF therapy through G-CSF–induced neutrophil recruitment
Authors: Phan Vernon T. , Wu Xiumin , Cheng Jason H. , Sheng Rebecca X. , Chung Alicia S. , Zhuang Guanglei , Tran Christopher , Song Qinghua , Kowanetz Marcin , Sambrone Amy , Tan Martha , Meng Y. Gloria , Jackson Erica L. , Peale Franklin V. , Junttila Melissa R. , Ferrara Napoleone
Published: March 2013

Granulocyte-colony stimulating factor (G-CSF) promotes mobilization of CD11b
+
Gr1
+
myeloid cells and has been implicated in resistance to anti-VEGF therapy in mouse models. High G-CSF production has been associated with a poor prognosis in cancer patients. Here we show that activation of the RAS/MEK/ERK pathway regulates G-CSF expression through the Ets transcription factor. Several growth factors induced G-CSF expression by a MEK-dependent mechanism. Inhibition of G-CSF release with a MEK inhibitor markedly reduced G-CSF production in vitro and synergized with anti-VEGF antibodies to reduce CD11b
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Ly6G
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neutrophil mobilization and tumor growth and led to increased survival in animal models of cancer, including a genetically engineered mouse model of pancreatic adenocarcinoma. Analysis of biopsies from pancreatic cancer patients revealed increased phospho-MEK, G-CSF, and Ets expression and enhanced neutrophil recruitment compared with normal pancreata. These results provide insights into G-CSF regulation and on the mechanism of action of MEK inhibitors and point to unique anticancer strategies.
Single dopaminergic neurons that modulate aggression in
Drosophila
Authors: Alekseyenko Olga V. , Chan Yick-Bun , Li Ran , Kravitz Edward A.
Published: March 2013

Monoamines, including dopamine (DA), have been linked to aggression in various species. However, the precise role or roles served by the amine in aggression have been difficult to define because dopaminergic systems influence many behaviors, and all can be altered by changing the function of dopaminergic neurons. In the fruit fly, with the powerful genetic tools available, small subsets of brain cells can be reliably manipulated, offering enormous advantages for exploration of how and where amine neurons fit into the circuits involved with aggression. By combining the GAL4/upstream activating sequence (UAS) binary system with the Flippase (FLP) recombination technique, we were able to restrict the numbers of targeted DA neurons down to a single-cell level. To explore the function of these individual dopaminergic neurons, we inactivated them with the tetanus toxin light chain, a genetically encoded inhibitor of neurotransmitter release, or activated them with dTrpA1, a temperature-sensitive cation channel. We found two sets of dopaminergic neurons that modulate aggression, one from the T1 cluster and another from the PPM3 cluster. Both activation and inactivation of these neurons resulted in an increase in aggression. We demonstrate that the presynaptic terminals of the identified T1 and PPM3 dopaminergic neurons project to different parts of the central complex, overlapping with the receptor fields of DD2R and DopR DA receptor subtypes, respectively. These data suggest that the two types of dopaminergic neurons may influence aggression through interactions in the central complex region of the brain involving two different DA receptor subtypes.
Regional Lung Derecruitment and Inflammation during 16 Hours of Mechanical Ventilation in Supine Healthy Sheep
Authors: Tucci Mauro R. , Costa Eduardo L. V. , Wellman Tyler J. , Musch Guido , Winkler Tilo , Harris R. Scott , Venegas Jose G. , Amato Marcelo B. P. , Melo Marcos F. Vidal
Published: March 2013

Background:

Lung derecruitment is common during general anesthesia. Mechanical ventilation with physiological tidal volumes could magnify derecruitment, and produce lung dysfunction and inflammation. The authors used positron emission tomography to study the process of derecruitment in normal lungs ventilated for 16 h and the corresponding changes in regional lung perfusion and inflammation.

Methods:

Six anesthetized supine sheep were ventilated with VT = 8 ml/kg and positive end-expiratory pressure = 0. Transmission scans were performed at 2-h intervals to assess regional aeration. Emission scans were acquired at baseline and after 16 h for the following tracers: (1) 18F-fluorodeoxyglucose to evaluate lung inflammation and (2) 13NN to calculate regional perfusion and shunt fraction.

Results:

Gas fraction decreased from baseline to 16 h in dorsal (0.31 ± 0.13 to 0.14 ± 0.12, P < 0.01), but not in ventral regions (0.61 ± 0.03 to 0.63 ± 0.07, P = nonsignificant), with time constants of 1.5–44.6 h. Although the vertical distribution of relative perfusion did not change from baseline to 16 h, shunt increased in dorsal regions (0.34 ± 0.23 to 0.63 ± 0.35, P < 0.01). The average pulmonary net 18F-fluorodeoxyglucose uptake rate in six regions of interest along the ventral–dorsal direction increased from 3.4 ± 1.4 at baseline to 4.1 ± 1.5⋅10−3/min after 16 h (P < 0.01), and the corresponding average regions of interest 18F-fluorodeoxyglucose phosphorylation rate increased from 2.0 ± 0.2 to 2.5 ± 0.2⋅10−2/min (P < 0.01).

Conclusions:

When normal lungs are mechanically ventilated without positive end-expiratory pressure, loss of aeration occurs continuously for several hours and is preferentially localized to dorsal regions. Progressive lung derecruitment was associated with increased regional shunt, implying an insufficient hypoxic pulmonary vasoconstriction. The increased pulmonary net uptake and phosphorylation rates of 18F-fluorodeoxyglucose suggest an incipient inflammation in these initially normal lungs.
Cross-cultural variation in women's preferences for cues to sex- and stress-hormones in the male face
Authors: Moore F. R. , Coetzee V. , Contreras-Garduño J. , Debruine L. M. , Kleisner K. , Krams I. , Marcinkowska U. , Nord A. , Perrett D. I. , Rantala M. J. , Schaum N. , Suzuki T. N.
Published: March 2013

Women in the UK prefer the faces of men with low levels of the stress hormone cortisol, and the relationship is moderated by the sex hormone testosterone. In a Latvian sample, however, women's preferences were not affected by cortisol, and the interaction with testosterone differed from that of the UK. To further explore cross-cultural variation in preferences for facial cues to sex- and stress-hormones, we tested the preferences of women from 13 countries for facial composites constructed to differ in combinations of the hormones. We found significant relationships between a measure of societal development (the United Nations human development index 2011) and preferences for cues to testosterone in the face, and the interaction between preferences for cues to testosterone and cortisol. We also found a significant relationship between preferences for cues to testosterone and a societal-level measure of parasite stress. We conclude that societal-level ecological factors influence the relative value of traits revealed by combinations of sex- and stress-hormones.
Evidence for hearing loss in amblyopsid cavefishes
Authors: Niemiller Matthew L. , Higgs Dennis M. , Soares Daphne
Published: March 2013

The constant darkness of caves and other subterranean habitats imposes sensory constraints that offer a unique opportunity to examine evolution of sensory modalities. Hearing in cavefishes has not been well explored, and here we show that cavefishes in the family Amblyopsidae are not only blind but have also lost a significant portion of their hearing range. Our results showed that cave and surface amblyopsids shared the same audiogram profile at low frequencies but only surface amblyopsids were able to hear frequencies higher than 800 Hz and up to 2 kHz. We measured ambient noise in aquatic cave and surface habitats and found high intensity peaks near 1 kHz for streams underground, suggesting no adaptive advantage in hearing in those frequencies. In addition, cave amblyopsids had lower hair cell densities compared with their surface relative. These traits may have evolved in response to the loud high-frequency background noise found in subterranean pools and streams. This study represents the first report of auditory regression in a subterranean organism.
Experimental maturation of feathers: implications for reconstructions of fossil feather colour
Authors: McNamara Maria E. , Briggs Derek E. G. , Orr Patrick J. , Field Daniel J. , Wang Zhengrong
Published: March 2013

Fossil feathers often preserve evidence of melanosomes—micrometre-scale melanin-bearing organelles that have been used to infer original colours and patterns of the plumage of dinosaurs. Such reconstructions acknowledge that evidence from other colour-producing mechanisms is presently elusive and assume that melanosome geometry is not altered during fossilization. Here, we provide the first test of this assumption, using high pressure–high temperature autoclave experiments on modern feathers to simulate the effects of burial on feather colour. Our experiments show that melanosomes are retained despite loss of visual evidence of colour and complete degradation of other colour-producing structures (e.g. quasi-ordered arrays in barbs and the keratin cortex in barbules). Significantly, however, melanosome geometry and spatial distribution are altered by the effects of pressure and temperature. These results demonstrate that reconstructions of original plumage coloration in fossils where preserved features of melanosomes are affected by diagenesis should be treated with caution. Reconstructions of fossil feather colour require assessment of the extent of preservation of various colour-producing mechanisms, and, critically, the extent of alteration of melanosome geometry.
Resource assurance predicts specialist and generalist bee activity in drought
Authors: Minckley Robert L. , Roulston T'ai H. , Williams Neal M.
Published: March 2013

Many short-lived desert organisms remain in diapause during drought. Theoretically, the cues desert species use to continue diapause through drought should differ depending on the availability of critical resources, but the unpredictability and infrequent occurrence of climate extremes and reduced insect activity during such events make empirical tests of this prediction difficult. An intensive study of a diverse bee–plant community through a drought event found that bee specialists of a drought-sensitive host plant were absent in the drought year in contrast to generalist bees and to specialist bees of a drought-insensitive host plant. Different responses of bee species to drought indicate that the diapause cues used by bee species allow them to reliably predict host availability. Species composition of the bee community in drought shifted towards mostly generalist species. However, we predict that more frequent and extended drought, predicted by climate change models for southwest North America, will result in bee communities that are species-poor and dominated by specialist species, as found today in the most arid desert region of North America.
Brain reorganization, not relative brain size, primarily characterizes anthropoid brain evolution
Authors: Smaers J. B. , Soligo C.
Published: March 2013

Comparative analyses of primate brain evolution have highlighted changes in size and internal organization as key factors underlying species diversity. It remains, however, unclear (i) how much variation in mosaic brain reorganization versus variation in relative brain size contributes to explaining the structural neural diversity observed across species, (ii) which mosaic changes contribute most to explaining diversity, and (iii) what the temporal origin, rates and processes are that underlie evolutionary shifts in mosaic reorganization for individual branches of the primate tree of life. We address these questions by combining novel comparative methods that allow assessing the temporal origin, rate and process of evolutionary changes on individual branches of the tree of life, with newly available data on volumes of key brain structures (prefrontal cortex, frontal motor areas and cerebrocerebellum) for a sample of 17 species (including humans). We identify patterns of mosaic change in brain evolution that mirror brain systems previously identified by electrophysiological and anatomical tract-tracing studies in non-human primates and functional connectivity MRI studies in humans. Across more than 40 Myr of anthropoid primate evolution, mosaic changes contribute more to explaining neural diversity than changes in relative brain size, and different mosaic patterns are differentially selected for when brains increase or decrease in size. We identify lineage-specific evolutionary specializations for all branches of the tree of life covered by our sample and demonstrate deep evolutionary roots for mosaic patterns associated with motor control and learning.