bluuebunny/crossref_metadata_2025 huggingface dataset:
Increasing the availability and spatial variation of spawning habitats through ascending baseflows
Authors: Goodman D. H. , Som N. A. , Hetrick N. J.
Published: July 2018

Precipitation in fall and winter is important to recharge aquifers in Northern California and the Pacific Northwestern United States, causing the baseflow in rivers ascend during the time when Chinook salmon (Oncorhynchus tshawytscha) construct redds. Herein, we evaluate the availability of spawning habitats under a constant streamflow common in regulated rivers against ascending baseflows patterned from free‐flowing rivers. A binomial logistic regression model was applied to predict the suitability of redd locations based on physical characteristics. Next, two‐dimensional hydrodynamic habitat models were developed at two locations representing a broad range of channel forms common in large rivers. Hydrodynamic and habitat models were leveraged together to simulate the quality, amount, and spatial distribution of spawning habitat at a series of individual flow rates, as well as the combined effect of those flow rates through a spawning season with ascending baseflows. Ascending baseflows increased the abundance of spawning habitat over individual streamflows at a site where the river channel is confined by levee‐like features. However, improvements were greater at an unconfined site that facilitated lateral connectivity and greater expansion of wetted channel area as streamflows increased. Ascending baseflows provided spatial separation in preferred habitats over a spawning season, which may reduce the risk of superimposition among runs or among species. Ascending baseflows provided a benefit across the range of hydrologic regimes in a 100‐year gauge record ranging from 20% to 122% improvements in habitat area over low streamflows that are currently used to manage for spawning habitat. Although replicating natural flow regimes in managed systems can be impossible or impractical, these results demonstrate that incorporating elements of the natural flow regime like ascending baseflows can benefit the restoration and conservation of riverine species.
Multiframe message broadcast in agility link based navigation satellite network
Authors: Hou Zhenwei , Yi Xianqing , Zhao Yue
Published: July 2018

The agility link based navigation satellite network suffers from a lack of continuous end‐to‐end connectivity. Message transmitting relies on a store‐forward mechanism—ie, data are sent from one node to another, depending on the communication opportunities, termed contacts, which arise when 2 nodes are connected by a link. To address the technical issues in such networks, the common approach is termed delay‐tolerant networking. However, the problem becomes more complicated when the message is subdivided into several frames for the limited transmission capacity of one contact. In this paper, we formalize the multiframe message broadcast problem where node may possess different knowledge, such as contact plans and message distribution, which depict the state of network and is helpful for data transmission. With the different amount of the knowledge, we investigate several different transmission strategies. And we propose the theoretical models to evaluate the above transmission strategies. Simulations prove the accuracy of our model. We also find that, as expected, the strategy using more knowledge tends to perform better. To the best of our knowledge this is the first investigation of multiframe message broadcast issues in the agility link based navigation satellite network.
Young students' understanding of the relationship between inheritance and variation of traits using structural equation modeling
Authors: Ibourk Amal , Williams Michelle , Opperman Amanda , Cisterna Dante , Nazar Christina Restrepo , Xie Yiyu
Published: July 2018

Genetics has become increasingly important in everyday life, a fact that is reflected in state and national science education standards. This study examines the relationship between 474 fifth graders' understandings of the core ideas of inheritance of traits and variation of traits. A confirmatory factor analysis, supplemented with qualitative analyses of students’ responses, revealed a relationship between these concepts and contributed evidence about the nature of students' challenges in learning these ideas. While most students demonstrated some normative ideas, many struggled to explain variation of traits as resulting from equal inheritance of genetic information from two parents. Instead, they focused on generational patterns of visible traits or on the influence of nongenetic factors. Deepening understanding of young students' heredity‐related thinking can improve preparation of older students for learning advanced genetics‐related ideas.
Structural damage and ion‐channelling effects in a single‐crystal Si layer modified by medium‐heavy ions
Authors: Mikšová R. , Macková A. , Jagerová A. , Yatskiv R.
Published: July 2018

Structural modification after medium‐heavy ion irradiation was characterised by Rutherford backscattering spectrometry in the channelling mode (RBS‐C) for silicon‐on‐insulator (SOI) material. Silicon on insulator was irradiated using C+, 2+, N+, 2+, and O+, 2+ ions at fluences of 1 × 1014 and 1 × 1015 cm−2 and energies of 0.4, 3, and 5 MeV to follow the interplay of electronic and nuclear stopping and its influence on damage accumulation. The relative amount of displaced atoms in the surface‐irradiated layer was extracted from RBS‐C spectra and used, along with axial channel analysis, to study ion‐channelling effects in the modified crystalline lattice. The discussion of ion penetration through the modified crystalline layer of the SOI structure in channelling direction was supported by a Monte Carlo simulation (FLUX code) of He ion flux maps in a gradually modified Si crystalline upper layer taking into account the experimentally determined relative disorder extracted from RBS‐C.

The RBS‐C measurement shows an increase of the relative amount of displaced atoms mainly after irradiation using 0.4‐MeV ions at an ion fluence of 1 × 1015 cm−2. The narrowing effect of channels for He ion‐beam channelling experiment was observed in the irradiated silicon layers and discussed in connection with the irradiation parameters. The FLUX simulation, provided with the experimentally given value of the displaced atoms, has confirmed that it is not only the vacancies that can cause such a narrowing effect of the angular scan. The angular scan narrowing can be explained for predominately electronic stopping by induced crystalline‐cell modification.
Deposition of polyacrylic acid films on PDMS substrate in dielectric barrier corona discharge at atmospheric pressure
Authors: Bashir M. , Bashir S. , Khan H. U.
Published: July 2018

This paper reports on deposition of acrylic acid films polymerized by an efficient and cost‐effective technique of dielectric barrier corona discharge at atmospheric pressure. The liquid acrylic acid was vaporized and carried by argon gas into plasma to deposit polyacrylic acid films on polydimethylsiloxane substrate. A nonthermal corona discharge was generated in a pyrex flask using a steel tube‐to‐plate asymmetric electrode configuration. The plasma was excited using an in‐house developed power supply operating with continuous wave signals of 10‐kHz frequency. The emission spectra of plasma species were recorded to know their contribution during deposition process. The deposited surfaces were characterized using contact angle measurements, atomic force microscopy, Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy and film thickness measurements. A maximum film growth rate of 363 nm/min was achieved under optimal condition of discharge. The results suggest that this plasma technique is capable of depositing organic coatings with a high concentration of carboxylic functional groups that could be potentially used for biomedical and microfluidic applications.
Recent Advances toward the Rational Design of Efficient Bifunctional Air Electrodes for Rechargeable Zn–Air Batteries
Authors: Meng Fan‐Lu , Liu Kai‐Hua , Zhang Yan , Shi Miao‐Miao , Zhang Xin‐Bo , Yan Jun‐Min , Jiang Qing
Published: July 2018

Large‐scale application of renewable energy and rapid development of electric vehicles have brought unprecedented demand for advanced energy‐storage/conversion technologies and equipment. Rechargeable zinc (Zn)–air batteries represent one of the most promising candidates because of their high energy density, safety, environmental friendliness, and low cost. The air electrode plays a key role in managing the many complex physical and chemical processes occurring on it to achieve high performance of Zn–air batteries. Herein, recent advances of air electrodes from bifunctional catalysts to architectures are summarized, and their advantages and disadvantages are discussed to underline the importance of progress in the evolution of bifunctional air electrodes. Finally, some challenges and the direction of future research are provided for the optimized design of bifunctional air electrodes to achieve high performance of rechargeable Zn–air batteries.
Reproducible Enhancement of Fluorescence by Bimetal Mediated Surface Plasmon Coupled Emission for Highly Sensitive Quantitative Diagnosis of Double‐Stranded DNA
Authors: Tran Nhu Hoa Thi , Trinh Kieu The Loan , Lee Jun‐Ho , Yoon Won Jung , Ju Heongkyu
Published: July 2018

Plasmonic enhancement of fluorescence from SYBR Green I conjugated with a double‐stranded DNA (dsDNA) amplicon is demonstrated on polymerase chain reaction (PCR) products. Theoretical computation leads to use of the bimetallic (Au 2 nm–Ag 50 nm) surface plasmons due to larger local fields (higher quality factors) than monometallic (Ag or Au) ones at both dye excitation and emission wavelengths simultaneously, optimizing fluorescence enhancement with surface plasmon coupled emission (SPCE). Two kinds of reverse Kretschmann configurations are used, which favor, in signal‐to‐noise ratio, a fluorescence assay that uses optically dense buffer such as blood plasma. The fluorescence enhancement (12.9 fold at maximum) with remarkably high reproducibility (coefficient of variation (CV) < 1%) is experimentally demonstrated. This facilitates credible quantitation of enhanced fluorescence, however unlikely to obtain by localized surface plasmons. The plasmon‐induced optical gain of 46 dB due to SPCE‐active dye molecules is also estimated. The fluorescence enhancement technologies with PCR enables LOD of the dsDNA template concentration of ≈400 fg µL−1 (CV < 1%), the lowest ever reported in DNA fluorescence assay to date. SPCE also reduces photobleaching significantly. These technologies can be extended for a highly reproducible and sufficiently sensitive fluorescence assay with small volumes of analytes in multiplexed diagnostics.
Continuous, Spontaneous, and Directional Water Transport in the Trilayered Fibrous Membranes for Functional Moisture Wicking Textiles
Authors: Miao Dongyang , Huang Zhan , Wang Xianfeng , Yu Jianyong , Ding Bin
Published: July 2018

Directional water transport is a predominant part of functional textiles used for continuous sweat release in daily life. However, it has remained a great challenge to design such textiles which ensure continuous directional water transport and superior prevention of water penetration in the reverse direction. Here, a scalable strategy is reported to create trilayered fibrous membranes with progressive wettability by introducing a transfer layer, which can guide the directional water transport continuously and spontaneously, thus preventing the skin from being rewetted. The resulting trilayered fibrous membranes exhibit a high one‐way transport index R (1021%) and a desired breakthrough pressure (16.1 cm H2O) in the reverse direction, indicating an ultrahigh directional water transport capacity. Moreover, on the basis of water transport behavior, a plausible mechanism is proposed to provide insight into the integrative and cooperative driving forces at the interfaces of trilayered hydrophobic/transfer/superhydrophilic fibrous membranes. The successful synthesis of such fascinating materials would be valuable for the design of functional textiles with directional water transport properties for personal drying applications.
Sulfur‐Deficient Bismuth Sulfide/Nitrogen‐Doped Carbon Nanofibers as Advanced Free‐Standing Electrode for Asymmetric Supercapacitors
Authors: Zong Wei , Lai Feili , He Guanjie , Feng Jianrui , Wang Wei , Lian Ruqian , Miao Yue‐E , Wang Gui‐Chang , Parkin Ivan P. , Liu Tianxi
Published: July 2018

The use of free‐standing carbon‐based hybrids plays a crucial role to help fulfil ever‐increasing energy storage demands, but is greatly hindered by the limited number of active sites for fast charge adsorption/desorption processes. Herein, an efficient strategy is demonstrated for making defect‐rich bismuth sulfides in combination with surface nitrogen‐doped carbon nanofibers (dr‐Bi2S3/S‐NCNF) as flexible free‐standing electrodes for asymmetric supercapacitors. The dr‐Bi2S3/S‐NCNF composite exhibits superior electrochemical performances with an enhanced specific capacitance of 466 F g−1 at a discharge current density of 1 A g−1. The high performance of dr‐Bi2S3/S‐NCNF electrodes originates from its hierarchical structure of nitrogen‐doped carbon nanofibers with well‐anchored defect‐rich bismuth sulfides nanostructures. As modeled by density functional theory calculation, the dr‐Bi2S3/S‐NCNF electrodes exhibit a reduced OH− adsorption energy of ‐3.15 eV, compared with that (–3.06 eV) of defect‐free bismuth sulfides/surface nitrogen‐doped carbon nanofiber (df‐Bi2S3/S‐NCNF). An asymmetric supercapacitor is further fabricated by utilizing dr‐Bi2S3/S‐NCNF hybrid as the negative electrode and S‐NCNF as the positive electrode. This composite exhibits a high energy density of 22.2 Wh kg−1 at a power density of 677.3 W kg−1. This work demonstrates a feasible strategy to construct advanced metal sulfide‐based free‐standing electrodes by incorporating defect‐rich structures using surface engineering principles.
Preparation, Characterization, and Biodegradability Assessment of Maize Starch‐(PVOH)/Clay Nanocomposite Films
Authors: Katerinopoulou Katerina , Giannakas Aris , Barkoula Nektaria‐Marianthi , Ladavos Athanasios
Published: July 2018

This study is focused on the preparation, characterization, and biodegradability assessment of clay nanocomposite films based on plasticized maize starch, prepared via solution casting method. Intercalated nano‐structure is achieved in all obtained films. Mechanical properties of the films prove to be dependent on the content of plasticizer (Glycerol) and poly‐vinyl‐alcohol (PVOH). Nanocomposite film with 10 wt% Glycerol and 20 wt% PVOH content possesses high stiffness and strength, but it is very brittle while nanocomposite film with 20 wt% Glycerol and 10 wt% PVOH content possesses reduced stiffness and strength but enhanced elongation at break, and film forming capability. Thermal stability of plasticized maize starch increases by 50 °C after addition of both PVOH and montmorillonite while water vapor transmission rate (WVTR) is reduced by 74% in comparison to the plasticized maize starch film. The biodegradation process increases in films with high starch content, while it is slow down when PVOH is added.
Repurposing the Cord Blood Bank for Haplobanking of HLA-Homozygous iPSCs and Their Usefulness to Multiple Populations
Authors: Lee Suji , Huh Ji Young , Turner David M. , Lee Soohyeon , Robinson James , Stein Jeremy E. , Shim Sung Han , Hong Chang Pyo , Kang Myung Seo , Nakagawa Masato , Kaneko Shin , Nakanishi Mahito , Rao Mahendra S. , Kurtz Andreas , Stacey Glyn N. , Marsh Steven G.E. , Turner Marc L. , Song Jihwan
Published: July 2018

Although autologous induced pluripotent stem cells (iPSCs) can potentially be useful for treating patients without immune rejection, in reality it will be extremely expensive and labor-intensive to make iPSCs to realize personalized medicine. An alternative approach is to make use of human leukocyte antigen (HLA) haplotype homozygous donors to provide HLA matched iPSC products to significant numbers of patients. To establish a haplobank of iPSCs, we repurposed the cord blood bank by screening ∼4,200 high resolution HLA typed cord blood samples, and selected those homozygous for the 10 most frequent HLA-A,-B,-DRB1 haplotypes in the Korean population. Following the generation of 10 iPSC lines, we conducted a comprehensive characterization, including morphology, expression of pluripotent markers and cell surface antigens, three-germ layer formation, vector clearance, mycoplasma/microbiological/viral contamination, endotoxin, and short tandem repeat (STR) assays. Various genomic analyses using microarray and comparative genomic hybridization (aCGH)-based single nucleotide polymorphism (SNP) and copy number variation (CNV) were also conducted. These 10 HLA-homozygous iPSC lines match 41.07% of the Korean population. Comparative analysis of HLA population data shows that they are also of use in other Asian populations, such as Japan, with some limited utility in ethnically diverse populations, such as the UK. Taken together, the generation of the 10 most frequent Korean HLA-homozygous iPSC lines serves as a useful pointer for the development of optimal methods for iPSC generation and quality control and indicates the benefits and limitations of collaborative HLA driven selection of donors for future stocking of worldwide iPSC haplobanks.
The Adaptive Remodeling of Stem Cell Niche in Stimulated Bone Marrow Counteracts the Leukemic Niche
Authors: Jeong Seon-Yeong , Kim Jin-A , Oh Il-Hoan
Published: July 2018

Accumulating studies have shown the cellular nature of hematopoietic stem cell (HSC) niche in bone marrow (BM) and their degenerative changes under leukemic conditions. However, the dynamic adaptation of niche cells to changes in physiological stimulatory signals remains largely uncharacterized. Here, we have established a niche stimulation model induced by 5-fluorouracil. This model reveals a rapid and reversible conversion of mesenchymal cells into niche-like stromal cells, which exhibit a platelet-derived growth factor receptor-alpha+/leptin receptor+ (PL) phenotype. These cells selectively induce the niche signaling molecule, Jagged-1, but not CXCL12, to initiate a stimulation-induced regeneration of HSCs in a Jagged-1 dependent manner. Conversion of mesenchymal cells into niche-like cells occurred independently of mitotic activation. The conversion was accompanied by the acquisition of primitive mesenchymal cell characteristics, including the rapid induction of stage specific embryonic antigen-3 and the acquisition of clonogenic potential. The stimulation-induced remodeling of the BM niche resulted in a positive stimulatory effect on the regeneration of normal HSC, but exerted inhibitory effects on leukemic cells, leading to a competitive advantage for normal HSCs in the BM niche and prolonged survival of mice engrafted with leukemic cells. Thus, the reactive conversion of mesenchymal stroma into niche-like cells reveals the adaptive changes of the BM microenvironment to stimuli, and provides insight on the remodeling of niche toward pronormal/antileukemic microenvironment, which can counteract the progressive proleukemic changes driven by the leukemic niche. Our study raises the potential for antileukemic niche targeting therapy.
Fms-Like Tyrosine Kinase 3-Ligand Contributes to the Development and Function of the Subpopulation of CD8α+ Plasmacytoid Precursor Dendritic Cells in CD8+/TCR− Facilitating Cells
Authors: Huang Yiming , Xu Hong , Miller Thomas , Wen Yujie , Ildstad Suzanne T.
Published: July 2018

Facilitating cells (FC) are a CD8+TCR− bone marrow subpopulation that enhance engraftment of purified hematopoietic stem cells (HSC) and induce antigen-specific CD4+CD25+FoxP3+ regulatory T cell (Treg) in vivo. The major subpopulation in FC resembles plasmacytoid precursor dendritic cells (p-preDC) both phenotypically and functionally. Here, we report that the number of FC was significantly reduced in Fms-like tyrosine kinase 3-ligand-knockout (Flt3-L-KO) mice. Specifically, there was a selective decrease in the B220+CD11c+CD11b− p-preDC FC subpopulation. The p-preDC FC subpopulation in FC total is restored after Flt3-L administration to Flt3-L-KO mice. FC from Flt3-L-KO donors exhibit impaired facilitation of allogeneic HSC engraftment in ablatively conditioned mice (B6 → NOD) as well as in mice conditioned with reduced intensity conditioning (B6 → BALB/c). In addition, the number of CD4+CD25+Foxp3+ Treg from Flt3-L-KO mice is significantly decreased. This was associated with the expression of chemokine receptor CXCR3+ or CCR5+ on Treg. Treg from the spleen of Flt3-L-KO mice showed impaired facilitation of engraftment of allogeneic HSC compared to wild-type Treg. Flt3-L treatment significantly expanded Treg, and restored their facilitating function. These results suggest that Flt3-L is an important growth factor in the development and homeostasis of p-preDC FC and in the role of FC inducing generation of Treg. Flt3-L provides potent immunoregulatory properties that may be clinically useful to improve tolerance induction and enhance the function of allogeneic cell therapies.
JAK2V617F Megakaryocytes Promote Hematopoietic Stem/Progenitor Cell Expansion in Mice Through Thrombopoietin/MPL Signaling
Authors: Zhang Yu , Lin Chi Hua Sarah , Kaushansky Kenneth , Zhan Huichun
Published: July 2018

The myeloproliferative neoplasms (MPNs) are stem cell disorders characterized by hematopoietic stem/progenitor cell (HSPC) expansion and overproduction of mature blood cells. The acquired kinase mutation JAK2V617F plays a central role in these disorders. The mechanisms responsible for HSPC expansion in MPNs are not fully understood, limiting the effectiveness of current treatments. One hallmark feature of the marrow in patients with MPNs is megakaryocyte (MK) hyperplasia. Previously, we reported that JAK2V617F-bearing MKs cause a murine myeloproliferative syndrome with HSPC expansion. Here we show that JAK2V617F MKs promote MPN stem cell function by inducing HSPC quiescence with increased repopulating capacity. In addition, we demonstrate that thrombopoietin and its receptor MPL are critical for the JAK2V617F-bearing MK-induced myeloproliferation, both by directly affecting the quantity and quality of MKs and by altering the MK–endothelial interaction and vascular niche function. Therefore, targeting HSPC niche-forming MKs and/or their interactions within the vascular niche could provide novel, more effective therapeutic strategies in patients with MPNs.
Effect of supplementary cementitious materials on the resistance of cement paste to carbonic acid water
Authors: Yin Suhong , Chen Yun , Yang Yongfeng , Huang Haoliang , Lv Hui
Published: July 2018

Cement pastes blended with fly ash or slag suffering from carbonic acid water were investigated. Thermogravimetric analysis was performed to determine the effect of fly ash and slag on CH content in cement pastes. Mercury intrusion porosimetry was used to characterize the effect of fly ash and slag on pore structure of cement pastes. Decalcification shrinkage and corrosion depth were determined to characterize the deterioration of cement paste after corrosion. The results show that the decalcification shrinkage is related to the initial CaO content and the composition of CSH gel. The corrosion depth depends on its initial CH content and pore structure. The results show that the paste blended with both fly ash and slag has good resistance to carbonic acid water in terms of decalcification shrinkage (reduced by nearly one half compared by the largest one) together with corrosion depth (reduced by nearly one third compared by the largest one). Furthermore, H2CO3 diffusion coefficient of the paste as a function of time was determined, which can be used to predict the durability of the pastes.
Influence of steel, glass and polymer fibers on the cracking behavior of reinforced concrete beams under flexure
Authors: Conforti Antonio , Zerbino Raúl , Plizzari Giovanni A.
Published: July 2018

The use of fibers can improve the behavior at serviceability limit states (crack and deflection control) and ultimate limit states (bearing capacity) of reinforced concrete (RC) elements under flexure. Fibers reinforcement provides a postcracking resistance, leading RC element to have a more diffused crack patterns characterized by narrower and more closely spaced cracks. Some doubts are instead related to RC element ductility, which can be affected by crack localization after rebar yielding. However, most of experiments present in literature relate only to elements in steel fiber reinforced concrete with significant residual strengths (f
R,1 and f
R,3 greater than 3.5–4.0 MPa). This paper aims to evaluate the influence of different fiber type (steel, glass, or polymer macrofibers) on the cracking and strength capacity of RC beams under flexure by using a broad range of Fiber Reinforced Concrete (FRC) toughness (1.6 ≤ f
R,1 ≤ 5.1 MPa and 0.8 ≤ f
R,3 ≤ 4.5 MPa). Twenty‐one small scale RC beams with a typical value of longitudinal reinforcement ratio (0.87%) were tested under flexure. Crack and deflection control, as well as bearing capacity and crack localization were evaluated as a function of FRC toughness. Finally, results were compared against mean crack spacing and strength capacity predictions of fib Model Code 2010.
A lattice‐shaped friction device and its performance in weak‐story prevention
Authors: Zhu Li‐Hua , Li Gang , Li Hong‐Nan
Published: July 2018

Displacement‐dependent dampers with relatively low post‐yielding stiffness exhibits abrupt stiffness loss and can even induce notable damage concentrations under strong vibrations. A lattice‐shaped friction unit (LSFU) composed of steel strips and friction discs is proposed and it can dissipate most input energy through translational friction and rotational friction and provide post‐yielding stiffness through the axial strength of vertical strips. Measurements of the friction coefficient and torque coefficient ratio and quasi‐static analysis of the LSFU are conducted, the results indicate that the ratio rises first and then drops to a constant value. Under cyclic loading, the two friction mechanisms could work together effectively and the contribution of each component contained in the restoring force could be controlled by adjusting design parameters of the LSFU; the assembly accuracy of the components affect the resistance of vertical strips. The experiment results of two specimens are compared with those obtained from the developed formulas and numerical simulations. A design procedure and applicable style are proposed. Nonlinear seismic response analysis results show that these devices can reduce the displacement response effectively under small and moderate earthquakes and can also prevent concentrated damage and weak‐story occurrence in the structure relative to friction‐damped brace frame in strong earthquakes.
Synthesis and X‐ray Crystal Structures of Ga‐substituted Distibenes [L(X)GaSb]2
Authors: Krüger Julia , Schoening Juliane , Ganesamoorthy Chelladurai , John Lukas , Wölper Christoph , Schulz Stephan
Published: July 2018

The reactions of two equivalents of LGa {L = HC[C(Me)N(2,6‐iPr2C6H3)]2} with SbX3 (X = Br, I, OEt) proceed with elimination of LGaX2 and formation of Ga‐substituted distibenes [L(X)GaSb]2 [X = Br (1), I (2), OEt (3)]. Compounds 1 to 3 were characterized by heteronuclear NMR (1H, 13C), IR and UV/Vis spectroscopy, elemental analysis, and single‐crystal X‐ray diffraction.
Field theoretic renormalization study of interaction corrections to the universal ac conductivity of graphene
Authors: Teber S. , Kotikov A. V.
Published: July 2018

Abstract

The two-loop interaction correction coefficient to the universal ac conductivity of disorder-free intrinsic graphene is computed with the help of a field theoretic renormalization study using the Bogoliubov-Parasiuk-Hepp-Zimmermann prescription. Non-standard Ward identities imply that divergent subgraphs (related to Fermi velocity renormalization) contribute to the renormalized optical conductivity. Proceeding either via densitydensity or via current-current correlation functions, a single well-defined value is obtained:

$$ \mathcal{C}=\left.\left(19-6\pi \right)/12\right)=0.01 $$

C
=

19
−
6
π

/
12

=
0.01

in agreement with the result first obtained by Mishchenko and which is compatible with experimental uncertainties.
Path-integral complexity for perturbed CFTs
Authors: Bhattacharyya Arpan , Caputa Pawel , Das Sumit R. , Kundu Nilay , Miyaji Masamichi , Takayanagi Tadashi
Published: July 2018

Abstract

In this work, we formulate a path-integral optimization for two dimensional conformal field theories perturbed by relevant operators. We present several evidences how this optimization mechanism works, based on calculations in free field theories as well as general arguments of RG flows in field theories. Our optimization is performed by minimizing the path-integral complexity functional that depends on the metric and also on the relevant couplings. Then, we compute the optimal metric perturbatively and find that it agrees with the time slice of the hyperbolic metric perturbed by a scalar field in the AdS/CFT correspondence. Last but not the least, we estimate contributions to complexity from relevant perturbations.
BPS Kerr-AdS time machines
Authors: Cvetič M. , Geng Wei-Jian , Lü H. , Pope C. N.
Published: July 2018

Abstract

It was recently observed that Kerr-AdS metrics with negative mass can describe smooth spacetimes that have a region within which naked closed time-like curves can arise, bounded by a velocity of light surface. Such spacetimes are sometimes known as time machines. In this paper we study the BPS limit of these metrics, and find that the mass and angular momenta become discretised. The completeness of the spacetime also requires that the asymptotic time coordinate be periodic, with precisely the same period as that which arises naturally for the global AdS, viewed as a hyperboliod in one extra dimension, in which the time machine spacetime is immersed. For the case of equal angular momenta in odd dimensions, we construct the Killing spinors explicitly, and show they are consistent with the global structure. Thus in examples where the solutions can be embedded in gauged supergravity, they will be supersymmetric. We also compare the global structure of the BPS AdS3 time machine with the BTZ black hole, and show that the global structure allows two different supersymmetric limits.
Spatial distribution ofVachellia karrooin Zimbabwean savannas (southern Africa) under a changing climate
Authors: Shekede Munyaradzi Davis , Murwira Amon , Masocha Mhosisi , Gwitira Isaiah
Published: July 2018

Climate change projections in southern Africa show a drier and a warmer future climate. It is not yet clear how these changes are going to affect the suitable habitat of bush encroacher woody species in southern African savannas. Maximum Entropy niche modelling technique was used to test the extent to which climate change is likely to affect the suitable habitat ofVachellia karrooin Zimbabwe based on six Global Climate Models (GCMs) from Coupled Model Intercomparison Project Phase 5 (CMIP5) and two Representative Concentration Pathways (RCPs) for the 2070s. An overlay analysis was then performed in a Geographic Information System based on the current and future bioclimatically suitable areas for the respective GCMs and RCPs. This was done to determine the potential effect of climate change on the focal species. Results show that temperature related variables are more important in explaining the spatial distribution ofV. karroothan precipitation related variables. In addition, results indicate an overall increase in the modelled suitable habitat forV.karrooby the 2070s across the GCMs and RCPs considered in this study. Specifically, the suitable habitat ofV.Karroois projected to increase by a maximum of 57,594 km2signifying a 69% increase from the current suitable habitat (83,674 km2). The suitable areas are projected to increase in eastern, western and south eastern parts of Zimbabwe. These results imply that improved understanding of the response of woody species to a changing climate is important for managing bush encroachment in savanna ecosystems.
Future physician-scientists: could we catch them young? Factors influencing intrinsic and extrinsic motivation for research among first-year medical students
Authors: Ommering Belinda W. C. , Van Blankenstein Floris M. , Waaijer Cathelijn J. F. , Dekker Friedo W.
Published: July 2018

Introduction The medical field is currently facing a physician-scientist shortage. One possible solution is to direct medical students towards a research oriented career. To do so, knowledge is needed on how to motivate medical students to do research. Therefore, this study examines motivation for research and identifies factors influencing intrinsic and extrinsic motivation for research among first-year medical students. Methods First-year medical students were surveyed at the beginning of their bachelor’s program in 2016. On a 7-point Likert scale, students reported their motivation for research, self-efficacy, perceptions of research, curiosity, and need for challenge. Regression analyses were used to examine the influence of these factors on students’ motivation for research. Results Out of 316 approached students, 315 participated (99.7%). On average, students scored 5.49 on intrinsic, and 5.66 on extrinsic motivation for research. All factors measured influenced intrinsic and extrinsic motivation for research significantly and positively, also after adjusting for gender and age. Cumulative regression showed that these factors explained 39.6% of the variance in intrinsic, and 14% in extrinsic motivation for research. Discussion All factors play an important role in intrinsic and, to a lesser extent, extrinsic motivation for research. First-year medical students’ motivation for research could be enhanced by stimulating positive self-efficacy beliefs, positive perceptions of research, and curiosity. Also, it is important to fulfil students’ needs for challenge by stimulating them to actively conduct research. Thus, to catch students young and cultivate physician-scientists, students should be stimulated to engage in research from the beginning of medical training.
Report on the Facilitation on the Activation of the Jurisdiction of the International Criminal Court over the Crime of Aggression (Int’l Crim. Ct.) & Resolution ICC-ASP/16/RES.5 on the Activation of the Jurisdiction of the Court over the Crime of Aggression
Authors: McDougall Carrie
Published: July 2018

On December 14, 2017, the International Criminal Court's (ICC) Assembly of States Parties (ASP or Assembly) adopted a resolution activating the ICC's jurisdiction over the crime of aggression as of July 17, 2018. As a result, the leaders of states now face the possibility of being held individually criminally responsible for unlawful acts of inter-state armed force. The resolution has thus rightly been hailed as historic—notwithstanding the significant limitation on the Court's jurisdiction accepted as the price of activation.
THE “RALLY ’ROUND THE FLAG” EFFECT IN TERRITORIAL DISPUTES: EXPERIMENTAL EVIDENCE FROM JAPAN–CHINA RELATIONS
Authors: Kobayashi Tetsuro , Katagiri Azusa
Published: July 2018

This study examines the impact of China's growing territorial ambitions on Japanese public opinion. By experimentally manipulating perceived territorial threats from China, we tested two potential mechanisms of increased support for a conservative incumbent leader in Japan. The first is the “rally ’round the flag” model, in which threats universally boost support for the leader through emotion. The second is the “reactive liberal” model, in which support from conservatives remains constant, but threatened liberals move toward supporting the conservative leader. Two survey experiments provided no support for the emotion-based “rally ’round the flag” model, but they lent support for the reactive liberal model in explaining the impact on Japanese public opinion. However, the second experiment indicated that priming with an image of the prime minister that highlights his role as the supreme commander of the national defense forces completely eliminated the gain in approval rates among liberals.
Blooms of aberrant planktic foraminifera across the K/Pg boundary in the Western Tethys: causes and evolutionary implications
Authors: Arenillas Ignacio , Arz José A. , Gilabert Vicente
Published: July 2018

We report a detailed study of the different categories and types of abnormal morphologies in planktic foraminifera recognizable in the lowermost Danian, mainly from the El Kef and Aïn Settara sections, Tunisia. Various types of abnormalities in the test morphology were identified, including protuberances near the proloculus, abnormal chambers, double or twinned ultimate chambers, multiple ultimate chambers, abnormal apertures, distortion in test coiling, morphologically abnormal tests, attached twins or double tests, and general monstrosities. Detailed biostratigraphic and quantitative studies of the Tunisian sections documented a major proliferation of aberrant planktic foraminifera (between approximately 5% and 18% in relative abundance) during the first 200 Kyr of the Danian, starting immediately after the Cretaceous/Paleogene (K/Pg) boundary mass extinction (spanning from theGuembelitria cretaceaZone to the lower part of theP. pseudobulloidesZone). This contrasts with the proportionately low frequency of aberrant tests (generally <2%) identified within the uppermost Maastrichtian, suggesting more stable environmental conditions during the last ~50–100 Kyr of the Cretaceous. Two main pulses with abundant aberrant tests were recognized in the earliest Danian, the one recorded in the well-known K/Pg boundary clay being the more intense of those (maxima of >18%). These main pulses of aberrants coincide approximately with relevant quantitative and evolutionary turnovers in the planktic foraminiferal assemblages. In this paper, we explore the relation of these high values of the foraminiferal abnormality index with the environmental changes induced by the meteorite impact of Chicxulub in Yucatan, Mexico, and the massive eruptions of the Deccan Traps, India.
Evaluating the Radiocarbon Reservoir Effect in Lake Kutubu, Papua New Guinea
Authors: Schneider Larissa , Pain Colin F , Haberle Simon , Blong Russell , Alloway Brent V , Fallon Stewart J , Hope Geoff , Zawadzki Atun , Heijnis Henk
Published: July 2018

We examined the radiocarbon (14C) reservoir effect in Lake Kutubu using tephrochronology and terrestrial plant material to deliver a precise age-depth profile and sedimentation rates for this lake. Based on the presence of two tephra horizons (Tibito and Olgaboli), we found a reservoir age offset in sediments of between 1490 and 228014C yr using the sediment ages derived from the lead-210 (210Pb) dating method. The live submerged biological samples collected exhibited a higher reservoir age offset than the sediment. This is most likely a result of delayed transport of “bomb”14C from the atmosphere to aquatic and sedimentary system. The14C reservoir effect increased with distance from the lake inlet and also decreased with depth. Dissolution of14C-depleted carbon from surrounding limestone and direct in-wash of old soil or vegetation remnants from the catchment are the most likely causes of the14C reservoir effect. Based on limestone areas mapped in Papua New Guinea, we indicate lakes which may be subject to a significant14C reservoir effect. The results of this study demonstrate the magnitude of the14C reservoir effect in lakes and provide insights to the correct interpretation of past environmental and archaeological events in PNG.
Exclusion and Cooperation in Diverse Societies: Experimental Evidence from Israel
Authors: ENOS RYAN D. , GIDRON NOAM
Published: July 2018

It is well-established that in diverse societies, certain groups prefer to exclude other groups from power and often from society entirely. Yet as many societies are diversifying at an increasingly rapid pace, the need for cross-group cooperation to solve collective action problems has intensified. Do preferences for exclusion inhibit the ability of individuals to cooperate and, therefore, diminish the ability for societies to collectively provide public goods? Turning to Israel, a society with multiple overlapping and politically salient cleavages, we use a large-scale lab-in-the-field design to investigate how preferences for exclusion among the Jewish majority predict discriminatory behavior toward Palestinian Citizens of Israel. We establish that preferences for exclusion are likely symbolic attitudes, and therefore stable and dominating of other attitudes; are held especially strongly by low-status majority group members; and powerfully predict costly non-cooperation. This preferences/behavior relationship appears unaffected by mitigating factors proposed in the intergroup relations literature. The demonstrated influence of symbolic attitudes on behavior calls for further examination of the social roots of exclusionary preferences.
Distributive Politics with Vote and Turnout Buying
Authors: CASAS AGUSTIN
Published: July 2018

The objective of this paper is to model the incumbent’s allocation of efforts that maximize his electoral chances in the presence of both vote buying (persuasion) and turnout buying (mobilization). The existing literature on distributive politics concludes that political candidates should concentrate their campaigning efforts either on safe districts or on swing districts. This paper shows that when candidates can use both persuasion and mobilization strategies, and the ideology of voters is unknown to the incumbent party, a third option should be taken into account. In fact, the optimal allocation of resources—rather than focusing on safe or swing districts—should target opposition strongholds, that is, the incumbent should try to sway voters in those districts in which the challenger is favored. The intuition for this result is simple. Since the incumbent does not know individual preferences (he only observes the distribution of preferences in the districts), all voters in a given district look identical to him. Hence, when approaching voters in a district to buy their vote, the incumbent always faces the risk of buying the vote of his supporters (who would have voted for him anyway).
Par-delà les champs de compétence : L'affirmation du Québec en matière de guerre et de paix
Authors: Massie Justin , Lamontagne Marjolaine
Published: July 2018

La doctrine Gérin-Lajoie, qui fonde l'action internationale du Québec depuis les années 1960, s'exprime conventionnellement comme le prolongement externe des compétences internes du Québec. Comment alors expliquer que les élus québécois prennent régulièrement position sur certains conflits internationaux, qui relèvent pourtant clairement de la compétence du gouvernement fédéral ? Cet article offre un premier éclairage sur les motivations des élus québécois à se positionner sur des enjeux militaires ainsi qu'aux dynamiques qui les entourent. Trois hypothèses sont avancées et confrontées tour à tour à l'ensemble des prises de position des élus québécois depuis le 11 septembre 2001 en matière d'intervention militaire. Premièrement, la paradiplomatie québécoise pourrait être marquée par un nationalisme identitaire, agissant comme outil d'affirmation et de différenciation nationales par-delà les compétences provinciales. Deuxièmement, plutôt que de représenter une tendance à connotation identitaire, l'affirmation québécoise sur des enjeux de compétence fédérale pourrait être la manifestation d'une protodiplomatie. Troisièmement, les élus québécois pourraient s'aventurer sur le terrain de la sécurité internationale en raison de calculs électoraux. En somme, l'article cherche à évaluer si l'affirmation québécoise en matière de sécurité internationale est le fruit de motivations identitaires, souverainistes ou électorales.
STRONG APPROXIMATION THEOREM FOR ABSOLUTELY IRREDUCIBLE VARIETIES OVER THE COMPOSITUM OF ALL SYMMETRIC EXTENSIONS OF A GLOBAL FIELD
Authors: JARDEN MOSHE , RAZON AHARON
Published: July 2018

LetKbe a global field,$\mathcal{V}$a proper subset of the set of all primes ofK,$\mathcal{S}$a finite subset of$\mathcal{V}$, and${\tilde K}$(resp.Ksep) a fixed algebraic (resp. separable algebraic) closure ofKwith$K_\mathrm{sep}\{\subseteq}{\tilde K}$. Let Gal(K) = Gal(Ksep/K) be the absolute Galois group ofK. For each$\mathfrak{p}\in\mathcal{V}$, we choose a Henselian (respectively, a real or algebraic) closure$K_\mathfrak{p}$ofKat$\mathfrak{p}$in${\tilde K}$if$\mathfrak{p}$is non-archimedean (respectively, archimedean). Then,$K_{\mathrm{tot},\mathcal{S}}=\bigcap_{\mathfrak{p}\in\mathcal{S}}\bigcap_{\tau\in{\rm Gal}(K)}K_\mathfrak{p}^\tau$is the maximal Galois extension ofKinKsepin which each$\mathfrak{p}\in\mathcal{S}$totally splits. For each$\mathfrak{p}\in\mathcal{V}$, we choose a$\mathfrak{p}$-adic absolute value$|~|_\mathfrak{p}$of$K_\mathfrak{p}$and extend it in the unique possible way to${\tilde K}$. Finally, we denote the compositum of all symmetric extensions ofKbyKsymm. We consider an affine absolutely integral varietyVin$\mathbb{A}_K^n$. Suppose that for each$\mathfrak{p}\in\mathcal{S}$there exists a simple$K_\mathfrak{p}$-rational point$\mathbf{z}_\mathfrak{p}$ofVand for each$\mathfrak{p}\in\mathcal{V}\smallsetminus\mathcal{S}$there exists$\mathbf{z}_\mathfrak{p}\in V({\tilde K})$such that in both cases$|\mathbf{z}_\mathfrak{p}|_\mathfrak{p}\le1$if$\mathfrak{p}$is non-archimedean and$|\mathbf{z}_\mathfrak{p}|_\mathfrak{p}<1$if$\mathfrak{p}$is archimedean. Then, there exists$\mathbf{z}\in V(K_{\mathrm{tot},\mathcal{S}}\cap K_\mathrm{symm})$such that for all$\mathfrak{p}\in\mathcal{V}$and for all τ ∈ Gal(K), we have$|\mathbf{z}^\tau|_\mathfrak{p}\le1$if$\mathfrak{p}$is archimedean and$|\mathbf{z}^\tau|_\mathfrak{p}<1$if$\mathfrak{p}$is non-archimedean. For$\mathcal{S}=\emptyset$, we get as a corollary that the ring of integers ofKsymmis Hilbertian and Bezout.
A PERTURBATION AND GENERIC SMOOTHNESS OF THE VAFA–WITTEN MODULI SPACES ON CLOSED SYMPLECTIC FOUR-MANIFOLDS
Authors: TANAKA YUUJI
Published: July 2018

We prove a Freed–Uhlenbeck style generic smoothness theorem for the moduli space of solutions to the Vafa–Witten equations on a closed symplectic four-manifold by using a method developed by Feehan for the study of thePU(2)-monopole equations on smooth closed four-manifolds. We introduce a set of perturbation terms to the Vafa–Witten equations, and prove that the moduli space of solutions to the perturbed Vafa–Witten equations on a closed symplectic four-manifold for the structure groupSU(2) orSO(3) is a smooth manifold of dimension zero for a generic choice of the perturbation parameters.