bluuebunny/crossref_metadata_2025 huggingface dataset:
The Fokas method for integrable evolution equations on a time-dependent interval
Authors: Xia Baoqiang
Published: February 2019

We demonstrate how to use the Fokas method to analyze initial-boundary value problems for integrable evolution equations posed on a time-dependent interval. In particular, we implement this method to a general dispersive linear evolution equation with spatial derivatives of arbitrary order and to the nonlinear Schrödinger equation, formulated in the time-dependent domain l1(t) < x < l2(t), 0 < t < T, where l1(t) and l2(t) are given, real, twice differentiable functions whose first derivatives are monotonic, and T is a positive fixed constant.
Natural amplitudes of the ground state of the helium atom: Benchmark calculations and their relevance to the issue of unoccupied natural orbitals in the H2 molecule
Authors: Cioslowski Jerzy , Pra̧tnicki Filip
Published: February 2019

Employment of exact numerical quadratures in the evaluation of matrix elements involving highly accurate wavefunctions of helium (and its isoelectronic congeners) generated with the help of the regularized Krylov sequences of Nakatsuji results in an efficient algorithm for the calculation of natural orbitals and the corresponding natural amplitudes {λnl}. The results of such calculations are presented for the total of 600 natural orbitals pertaining to the ground state of the helium atom. The benchmark-quality values of {λnl} computed for 1 ≤ n ≤ 100 and 0 ≤ l ≤ 5 reveal gross inaccuracies in the previously published data. In particular, the dependence of λnl on n is found to follow very closely a simple power-scaling law λnl≈−Al (n+Bl)−4 with Al that, contrary to previous claims, varies only weakly with l. Even more importantly, the numerical trends observed in the present calculations strongly suggest that in the case of the ground state of the helium atom, the only positive-valued natural amplitude is that pertaining to the strongly occupied orbital, i.e., λ10. The relevance of this finding to the existence of unoccupied natural orbitals pertaining to the ground state wavefunction of the H2 molecule is discussed.
Tensile strain effects on C4N3H monolayer: Large Poisson's ratio and robust Dirac cone
Authors: Pan Hongzhe , Zhang Hongyu , Li Jianfu , Li Qingfang , Sun Yuanyuan , Wei Mingzhen , Zhu Hongyang , Wang Xiaoli
Published: February 2019

Recently, a novel two-dimensional (2D) metal-free organic material, the C4N3H monolayer, has been proposed and predicted to be a 2D Dirac material with high Fermi velocities. Herein, we investigated its mechanical properties and tensile strain effects on its electronic properties based on first-principles calculations. We demonstrated that this material is quite soft with small stiffness constants and can sustain large strains. Compared to many other 2D materials, this material presents a remarkable elastic anisotropy and a large Poisson's ratio, which are very important for strain engineering. We also found that the Dirac cone of this material is very robust against the tensile strains and the Fermi velocity is high. The small stiffness constant, large Poisson's ratio, robust Dirac cone, and high Fermi velocity make the C4N3H monolayer a promising material in high-speed flexible electronic devices.
Highly sensitive photo-detectors for the ultra-violet wavelength range based on a dielectric stack and a silicon on insulator substrate
Authors: Mikhelashvili V. , Shneider Y. , Sherman A. , Yofis S. , Ankonina G. , Eyal O. , Khanonkin I. , Eisenstein G.
Published: February 2019

We propose and demonstrate planar metal-insulator-semiconductor-metal photodetectors fabricated on a silicon-on-insulator substrate with an n-type silicon device layer. The gate insulator comprises a double layer dielectric stack of SiO2 and HfO2. Detectors with different electrode geometries were characterized in a wide wavelength range: from 245 nm to 880 nm. A responsivity of 1.77 A/W was achieved at 405 nm independent of the illumination intensity, while at 245 nm, the responsivity was found to be nonlinear and at an intensity of 8 μW/cm2, it reached a record value of 30.5 A/W. Local fringing electric fields across asymmetric metal-insulator-semiconductor and metal-semiconductor junctions, stemming from the insulator stack and a reduction of the effective barrier height under illumination, are assumed to cause the high responsivity at wavelengths longer than 365 nm. The super linear rise in responsivity for wavelengths shorter than 285 nm is due to deep trap states which are charged by the injected electrons.
Generation of arbitrary perfect Poincaré beams
Authors: Li Delin , Feng Shaotong , Nie Shouping , Chang Chenliang , Ma Jun , Yuan Caojin
Published: February 2019

We propose a method to generate arbitrary perfect Poincaré beams using one spatial light modulator (SLM). A polarization beam splitter is used to generate two polarization beams that are orthogonally (x and y) polarized. Half of the SLM helps shape the x-polarized beam; simultaneously, the other half of the SLM shapes the y-polarized beam. By adding different or the same spiral phases to the orthogonally polarized beams, any point on the Poincaré surface can be reached. The proposed approach is experimentally evaluated. The ring diameter remains the same when different polarization orders and topological charges are programmed. The generation of perfect Poincaré beams including fundamental Poincaré sphere, high-order Poincaré sphere, and hybrid Poincaré sphere are demonstrated in our system.
The role of hydrophobicity in the cold denaturation of proteins under high pressure: A study on apomyoglobin
Authors: Espinosa Yanis R. , Caffarena Ernesto R. , Grigera J. Raúl
Published: February 2019

An exciting debate arises when microscopic mechanisms involved in the denaturation of proteins at high pressures are explained. In particular, the issue emerges when the hydrophobic effect is invoked, given that hydrophobicity cannot elucidate by itself the volume changes measured during protein unfolding. In this work, we study by the use of molecular dynamics simulations and essential dynamics analysis the relation between the solvation dynamics, volume, and water structure when apomyoglobin is subjected to a hydrostatic pressure regime. Accordingly, the mechanism of cold denaturation of proteins under high-pressure can be related to the disruption of the hydrogen-bond network of water favoring the coexistence of two states, low-density and high-density water, which directly implies in the formation of a molten globule once the threshold of 200 MPa has been overcome.
Quantum spin transport to semiconductor quantum dots through superlattice
Authors: Hiura Satoshi , Itabashi Kodai , Takeishi Kazuki , Takayama Junichi , Kiba Takayuki , Murayama Akihiro
Published: February 2019

Spin transport properties from the GaAs/AlGaAs superlattice (SL) to InGaAs quantum dots (QDs) are studied by circularly polarized time-resolved photoluminescence spectroscopy of QD excited states with the selective excitation of SL miniband states. For the SL with a thinner barrier, we observe an effective carrier transport in SL owing to the stronger overlap of wavefunctions of adjacent quantum wells and a simultaneous highly efficient carrier injection into QDs. Moreover, the SL with a thinner barrier demonstrates a quantum spin transport to QDs maintaining high spin polarization during the transport process.
Enhanced interfacial perpendicular magnetic anisotropy in Fe/MgO heterostructure via interfacial engineering
Authors: Nazir Safdar , Jiang Sicong , Cheng Jianli , Yang Kesong
Published: February 2019

Interfacial perpendicular magnetic anisotropy in the Fe/MgO heterostructure has attracted increasing attention because of its potential usage in building out-of-plane magnetized magnetic tunnel junctions for spin-transfer-torque magnetic random-access memory devices. A large interfacial anisotropy constant (Ki) is required to achieve a high thermal stability that is critical for large-capacity magnetic tunnel junctions. Here, we show that inserting one layer of appropriate heavy elements (X) at the interface of Fe/MgO can significantly enhance Ki using first-principles electronic structure calculations. A total number of 33 X metal elements including 3d, 4d, and 5d transition metals and 4p, 5p, and 6p main group elements were considered. By analyzing the interfacial magnetic anisotropy and interfacial bonding strength of Fe/X/MgO, we are able to identify three promising heavy transition-metal elements including W, Re, and Pt for enhancing perpendicular magnetic anisotropy in Fe/MgO, with an improved Ki of 2.43, 2.37, and 9.74 mJ/m2, respectively. This work indicates that interfacial engineering is one effective way to modify the interfacial magnetic anisotropic property.
Kinetic pathway analysis of an α-helix in two protonation states: Direct observation and optimal dimensionality reduction
Authors: Jas Gouri S. , Childs Ed W. , Kuczera Krzysztof
Published: February 2019

Thermodynamically stable conformers of secondary structural elements make a stable tertiary/quaternary structure that performs its proper biological function efficiently. Formation mechanisms of secondary and tertiary/quaternary structural elements from the primary structure are driven by the kinetic properties of the respective systems. Here we have carried out thermodynamic and kinetic characterization of an alpha helical heteropeptide in two protonation states, created with the addition and removal of a proton involving a single histidine residue in the primary structure. Applying far-UV circular dichroism spectroscopy, the alpha helix is observed to be significantly more stable in the deprotonated state. Nanosecond laser temperature jump spectroscopy monitoring time-resolved tryptophan fluorescence on the protonated conformer is carried out to measure the kinetics of this system. The measured relaxation rates at a final temperature between 296K and 314 K generated a faster component of 20 ns–11 ns and a slower component of 314 ns–198 ns. Atomically detailed characterization of the helix-coil kinetic pathways is performed based on all-atom molecular dynamics trajectories of the two conformers. Application of clustering and kinetic coarse-graining with optimum dimensionality reduction produced description of the trajectories in terms of kinetic models with two to five states. These models include aggregate states corresponding to helix, coil, and intermediates. The “coil” state involves the largest number of conformations, consistent with the expected high entropy of this structural ensemble. The “helix” aggregate states are found to be mixed with the full helix and partially folded forms. The experimentally observed higher helix stability in the deprotonated form of the alpha helical heteropeptide is reflected in the nature of the “helix” aggregate state arising from the kinetic model. In the protonated form, the “coil” state exhibits the lowest free energy and longest lifetime, while in the deprotonated form, it is the “helix” that is found to be most stable. Overall, the coarse grained models suggest that the protonation of a single histidine residue in the primary structure induces significant changes in the free energy landscape and kinetic network of the studied helix-forming heteropeptide.
Edgetic perturbations to eliminate fixed-point attractors in Boolean regulatory networks
Authors: Campbell Colin , Albert Réka
Published: February 2019

The dynamics of complex biological networks may be modeled in a Boolean framework, where the state of each system component is either abundant (ON) or scarce/absent (OFF), and each component's dynamic trajectory is determined by a logical update rule involving the state(s) of its regulator(s). It is possible to encode the update rules in the topology of the so-called expanded graph, analysis of which reveals the long-term behavior, or attractors, of the network. Here, we develop an algorithm to perturb the expanded graph (or, equivalently, the logical update rules) to eliminate stable motifs: subgraphs that cause a subset of components to stabilize to one state. Depending on the topology of the expanded graph, these perturbations lead to the modification or loss of the corresponding attractor. While most perturbations of biological regulatory networks in the literature involve the knockout (fixing to OFF) or constitutive activation (fixing to ON) of one or more nodes, we here consider edgetic perturbations, where a node's update rule is modified such that one or more of its regulators is viewed as ON or OFF regardless of its actual state. We apply the methodology to two biological networks. In a network representing T-LGL leukemia, we identify edgetic perturbations that eliminate the cancerous attractor, leaving only the healthy attractor representing cell death. In a network representing drought-induced closure of plant stomata, we identify edgetic perturbations that modify the single attractor such that stomata, instead of being fixed in the closed state, oscillates between the open and closed states.
A cold atom radio-frequency magnetometer
Authors: Cohen Yuval , Jadeja Krishna , Sula Sindi , Venturelli Michela , Deans Cameron , Marmugi Luca , Renzoni Ferruccio
Published: February 2019

We propose and demonstrate a radio-frequency atomic magnetometer with sub-Doppler laser cooled rubidium-87. With a simple and compact design, our system demonstrates a sensitivity of 330 pT/Hz in an unshielded environment, thus matching or surpassing previously reported cold atom designs. By merging the multiple uses and the robustness of radio-frequency atomic magnetometers with the detailed control of laser cooling, our cold atom radio-frequency magnetometer has potential for moving applications of atomic magnetometry to high spatial resolutions. A direct impact in metrology for applied sciences, materials characterization, and nanotechnology can be anticipated.
Calculation of electron density and temperature of plasmas by using new Stark broadening formula of helium lines
Authors: Sadeghzadeh Lari E. , Ranjbar Askari H. , Meftah M. T. , Shariat M.
Published: February 2019

In this work, three helium lines are considered to find the density and the temperature of the electrons (Ne and Te) in a plasma jet. We have, at first, developed a new formula for Stark broadening through an exact contribution of the weak collisions of the free electrons with helium atoms (He). So, the sum of the weak and strong collision contributions to the spectral broadening is obtained as a function of the electron density Ne and the electron temperature Te: it is called the Stark broadening by the electron collisions with He atoms. By calculating resonance, Doppler, and van der Waals broadenings, measuring instrumental broadening, and using our experimental profiles, we have inferred the value of the full Stark broadening (by ion and electron collisions) for three helium lines (501 nm, 667 nm, and 728 nm). By using a relation between the full Stark broadening and electron collision broadening for each line, we have established a relation between the electron density and the electron temperature of the plasma for each line. The plot of the three corresponding functions Ne(Te) leads to have a good estimation of the electron density Ne and the electron temperature Te. The obtained result for Ne and Te is for a fixed value of the voltage, U, and the frequency, f. Repeated experiments for other values of voltage and frequency give other values of the electron density and the electron temperature.
Influence of bed proximity on the three-dimensional characteristics of the wake of a sharp-edged bluff body
Authors: Nasif G. , Balachandar R. , Barron R. M.
Published: February 2019

The gap flow effect in a wake is investigated to develop an improved picture of the formation of fluid structures via a numerical simulation of flow past a bluff body with two different clearances from the bed. These two cases are compared with the no-gap case which is considered as a reference case. The transient three-dimensional Navier-Stokes equations are numerically solved using a finite volume approach with the detached eddy simulation as the turbulence model. The effect of the free surface is included in the model by using the volume of fluid method. The fluid structures that are generated in the wake are identified using the λ2-criterion. It is found that the gap flow influences the formation of various types of fluid structures in the wake region. The horseshoe vortex appears to be attenuated as the gap size increases. The turbulent structures at the core of the wake appear to be disorganized and have the ability to extend further in the transverse direction in the absence of the horseshoe vortex. A new structure is identified in the wake flow when the gap size exceeds a threshold value. This structure acts to enhance the positive wall-normal velocity and accelerate the restoration of the free surface to its original position at shorter distances downstream of the bluff body. The lateral entrainment to the wake region is also enhanced as the gap is introduced in the wake flow.
Unique tension-compression asymmetry of nanoporous metallic glasses induced by surface effects
Authors: Zhang Jiacheng , Zhang Weixu
Published: February 2019

The mechanical properties of nanoporous (NP) metallic glasses (MGs) under uniaxial tension and compression are studied via molecular dynamics simulations in this work. The shrinking tendency within NP MGs, induced by the surface effects, results in the unique tension-compression asymmetry, i.e., the tensile yield strength is stronger than the compressive yield strength and the tensile yield strain is bigger than the compressive yield strain. This unique tension-compression asymmetry of NP MGs is contrary to that of the pore-free bulk MGs and the MGs with macroscopic pores. The strengthening phenomenon with the increase of the pore size is more remarkable for compression than tension due to the difference of elastic energy release during the deformation. Moreover, with the pore size decreasing, the deformation mechanism of NP MGs changes from catastrophic fracture with a single dominant shear band to homogeneous plastic deformation with multiple shear bands under both tensile loading and compressive loading. Our results are helpful in understanding the surface effects on NP materials and important for optimization design of NP materials.
Comment on “Exact solutions and singularities of an X-point collapse in Hall magnetohydrodynamics” [J. Math. Phys. 59, 061509 (2018)]
Authors: Brizard Alain J.
Published: February 2019

A recent paper by Janda [J. Math. Phys. 59, 061509 (2018)] presented a partial solution of the equations of dissipationless Hall magnetohydrodynamics in terms of the Weierstrass elliptic function. The present comment corrects a sign error in the analysis and offers a complete solution of dissipationless Hall magnetohydrodynamics in terms of the Jacobi elliptic functions.
Variability in egg and jelly-coat size and their contribution to target size for spermatozoa: a review for the Echinodermata
Authors: Deaker Dione J. , Foo Shawna A. , Byrne Maria
Published: February 2019

Fertilisation and development in broadcast-spawning marine invertebrates depends on the ability of the egg to attract spermatozoa and provision progeny. Echinoderm eggs have a jelly coat that facilitates sperm–egg collisions. We investigated variation in egg volume and target area for spermatozoa provided by the jelly coat within and between three sea urchin species (Heliocidaris erythrogramma, Heliocidaris tuberculata, Centrostephanus rodgersii), as well as across 22 echinoderm species for which data are available. Egg and jelly-coat size varied within spawns of individual females, between females of a species and between species. The jelly coat increased egg target area by 125–489% for echinoids with planktotrophic development. In general, planktotrophic echinoids (n=16) with larger eggs had thicker jelly coats, as did H. tuberculata females with larger eggs. Variability in egg and jelly-coat size within a species indicates that these traits are prone to maternal effects and may be influenced by factors such as sperm environment and offspring fitness that drive selection on egg investment. The greater variability in jelly-coat size compared with that of the egg has a large potential to affect fertilisation and should be considered in models of fertilisation kinetics. Egg size alone cannot be used as a metric to infer target size for spermatozoa.
CD4+T help promotes influenza virus-specific CD8+T cell memory by limiting metabolic dysfunction
Authors: Cullen Jolie G. , McQuilten Hayley A. , Quinn Kylie M. , Olshansky Moshe , Russ Brendan E. , Morey Alison , Wei Sanna , Prier Julia E. , La Gruta Nicole L. , Doherty Peter C. , Turner Stephen J.
Published: February 2019

Significance

Promoting effective CD8+T cell memory is a primary goal of T cell-based vaccination and immunotherapy strategies. While it is well established that CD4+T cell help is required for enduring CD8+T cell memory, how such help contributes to establishing optimal CD8+T cell memory generation and persistence remains unclear. In this study, we demonstrate that CD4+help at the time of priming ensures that memory CD8+T cells are programmed to engage metabolic biological pathways essential for effective recall responses. Such understanding has clear implications for the augmentation of vaccine therapies designed to promote protective T cell immunity.
Podocalyxin is required for maintaining blood–brain barrier function during acute inflammation
Authors: Cait Jessica , Hughes Michael R. , Zeglinski Matthew R. , Chan Allen W. , Osterhof Sabrina , Scott R. Wilder , Canals Hernaez Diana , Cait Alissa , Vogl A. Wayne , Bernatchez Pascal , Underhill T. Michael , Granville David J. , Murphy Timothy H. , Roskelley Calvin D. , McNagny Kelly M.
Published: February 2019

Significance

This article demonstrates a role for podocalyxin in blood–brain barrier (BBB) function. Podocalyxin expression on endothelial cells promotes the formation of adhesion interactions and barrier formation. Furthermore, it describes a neuroelectric phenotype elicited by a selective protease-activated receptor-1 (PAR-1) agonist. PAR-1 activation by serum proteases (e.g., thrombin) leaking into the central nervous system during inflammation has the potential to impact the course of brain injury and recovery. However, the role of PAR-1 in the pathophysiology of neuroinflammation is poorly understood. In summary, this study offers unique insight into the impact of PAR-1 activation in neuroinflammation and implicates podocalyxin as a therapeutic target for the manipulation of BBB permeability and the treatment of neurodegenerative disease.
Early onset preeclampsia in a model for human placental trophoblast
Authors: Sheridan Megan A. , Yang Ying , Jain Ashish , Lyons Alex S. , Yang Penghua , Brahmasani Sambasiva R. , Dai Aihua , Tian Yuchen , Ellersieck Mark R. , Tuteja Geetu , Schust Danny J. , Schulz Laura C. , Ezashi Toshihiko , Roberts R. Michael
Published: February 2019

We describe a model for early onset preeclampsia (EOPE) that uses induced pluripotent stem cells (iPSCs) generated from umbilical cords of EOPE and control (CTL) pregnancies. These iPSCs were then converted to placental trophoblast (TB) representative of early pregnancy. Marker gene analysis indicated that both sets of cells differentiated at comparable rates. The cells were tested for parameters disturbed in EOPE, including invasive potential. Under 5% O
2
, CTL TB and EOPE TB lines did not differ, but, under hyperoxia (20% O
2
), invasiveness of EOPE TB was reduced. RNA sequencing analysis disclosed no consistent differences in expression of individual genes between EOPE TB and CTL TB under 20% O
2
, but, a weighted correlation network analysis revealed two gene modules (CTL4 and CTL9) that, in CTL TB, were significantly linked to extent of TB invasion. CTL9, which was positively correlated with 20% O
2
(
P
= 0.02) and negatively correlated with invasion (
P
= 0.03), was enriched for gene ontology terms relating to cell adhesion and migration, angiogenesis, preeclampsia, and stress. Two EOPE TB modules, EOPE1 and EOPE2, also correlated positively and negatively, respectively, with 20% O
2
conditions, but only weakly with invasion; they largely contained the same sets of genes present in modules CTL4 and CTL9. Our experiments suggest that, in EOPE, the initial step precipitating disease is a reduced capacity of placental TB to invade caused by a dysregulation of O
2
response mechanisms and that EOPE is a syndrome, in which unbalanced expression of various combinations of genes affecting TB invasion provoke disease onset.
Two E3 ligases antagonistically regulate the UV-B response in
Arabidopsis
Authors: Ren Hui , Han Jiupan , Yang Panyu , Mao Weiwei , Liu Xin , Qiu Leilei , Qian Chongzhen , Liu Yan , Chen Zhiren , Ouyang Xinhao , Chen Xu , Deng Xing Wang , Huang Xi
Published: February 2019

Significance

Plant seedlings encounter increasing levels of UV-B irradiation during their emergence from soil as they undergo a light-induced developmental process termed photomorphogenesis. However, less is known about the molecular mechanisms underlying plant responses to this invisible part of the light spectrum. Here, we reveal that the UV-B light signal is interpreted coordinately by two sets of E3 ligases and a transcription factor in
Arabidopsis
. The UV-B–inducible E3 CUL4-DDB1–RUP1/RUP2 complex targets the master transcription factor HY5 for proteolysis. COP1 directly interacts with and degrades RUP1/RUP2 to stabilize HY5, ultimately promoting photomorphogenesis under UV-B light. These findings uncover the mechanism of plant responses to UV-B irradiation, and are critical to develop methods to improve plant growth and light energy utilization.
Human colon organoids reveal distinct physiologic and oncogenic Wnt responses
Authors: Michels Birgitta E. , Mosa Mohammed H. , Grebbin Britta M. , Yepes Diego , Darvishi Tahmineh , Hausmann Johannes , Urlaub Henning , Zeuzem Stefan , Kvasnicka Hans M. , Oellerich Thomas , Farin Henner F.
Published: February 2019

Constitutive Wnt activation upon loss of Adenoma polyposis coli (APC) acts as main driver of colorectal cancer (CRC). Targeting Wnt signaling has proven difficult because the pathway is crucial for homeostasis and stem cell renewal. To distinguish oncogenic from physiological Wnt activity, we have performed transcriptome and proteome profiling in isogenic human colon organoids. Culture in the presence or absence of exogenous ligand allowed us to discriminate receptor-mediated signaling from the effects of CRISPR/Cas9-induced APC loss. We could catalog two nonoverlapping molecular signatures that were stable at distinct levels of stimulation. Newly identified markers for normal stem/progenitor cells and adenomas were validated by immunohistochemistry and flow cytometry. We found that oncogenic Wnt signals are associated with good prognosis in tumors of the consensus molecular subtype 2 (CMS2). In contrast, receptor-mediated signaling was linked to CMS4 tumors and poor prognosis. Together, our data represent a valuable resource for biomarkers that allow more precise stratification of Wnt responses in CRC.
Getting into the thick (and thin) of it
Authors: Irving Thomas C. , Craig Roger
Published: February 2019

Irving and Craig reflect on new work showing that thick filament activation involves myosin motors returning to their OFF state during diastole.
An image reconstruction model regularized by edge-preserving diffusion and smoothing for limited-angle computed tomography
Authors: Xu Jinqiu , Zhao Yunsong , Li Hongwei , Zhang Peng
Published: February 2019

Limited-angle computed tomography is a very challenging problem in applications. Due to a high degree of ill-posedness, conventional reconstruction algorithms will introduce blurring along the directions perpendicular to the missing projection lines, as well as streak artifacts when applied on limited-angle data. Various models and algorithms have been proposed to improve the reconstruction quality by incorporating priors, among which the total variation, i.e. l
1 norm of gradient, and l
0 norm of the gradient are the most popular ones. These models and algorithms partially solve the blurring problem under certain situations. However, the fundamental difficulty remains. In this paper, we propose a reconstruction model for limited-angle computed tomography, which incorporates two regularization terms that play the role of edge-preserving diffusion and smoothing along the x-direction and y -direction respectively. Then, an alternating minimization algorithm is proposed to solve the model approximately. The proposed model is inspired by the theory of visible and invisible singularities of limited-angle data, developed by Quinto et al. By incorporating visible singularities as priors into an iterative procedure, the proposed algorithm could produce promising results and outperforms state-of-the-art algorithms for certain limited-angle computed tomography applications. Extensive experiments on both simulated data and real data are provided to validate our model and algorithm.
1. More
Authors: Hartley Jenny
Published: February 2019

Charles Dickens’s first two novels—The Posthumous Papers of the Pickwick Club and Oliver Twist—were published in monthly instalments, usually of two or three chapters at a time, beginning in 1836. Charles Dickens was also editing a new monthly magazine, Bentley’s Miscellany, and writing for theatre at this time. He was the talk of the town, his name everywhere. ‘More’ explains how contradiction and opposition fired Dickens’s imagination and were characteristics running throughout his writing. Oliver was a great success with many versions and manifestations. There were numerous translations and the invention of cinema at the end of the 19th century saw film versions, followed by adaptations for television, musicals, and theatre.
3. Character and plot
Authors: Hartley Jenny
Published: February 2019

Characters are what Charles Dickens is famous for. They crowd and flock through his novels, roughly 2,000 named characters, and multitudes more unnamed. The original illustrations by George Cruikshank and Hablot K. Browne, crammed with people, convey the sense of plenitude. ‘Character and plot’ describes the creation of some of Dickens’s characters, many of whom have achieved the fictional gold standard of life beyond the page, populating the empire of the collective imaginary. On the other hand, Dickens’s characterization has been targeted for criticism, as have his plots. His characters are condemned as caricatures with no inner life, his plots as improbable and impossible to follow.
5. Radical Dickens
Authors: Hartley Jenny
Published: February 2019

Charles Dickens was a life-long radical. According to Forster, it was Dickens’s childhood experiences that instilled ‘the hatred of oppression, the revolt against abuse of power, and the war with injustice under every form.’ Dickens would unfailingly take the side of the poor and the underdog. His vision darkened with age, but although his focus changed, the radicalism never left him. ‘Radical Dickens’ outlines his early targets and sledge-hammer blows through a variety of media. Throughout the 1850s, his magazine, Household Words, addressed important and controversial issues: factory conditions, slum housing, public health and hygiene, women’s employment, education, emigration, crime and prison discipline, and government bureaucracy and administration.
6. Dickensian
Authors: Hartley Jenny
Published: February 2019

Charles Dickens became an adjective in his own lifetime. By the 1850s, he was ‘Dickenesque’ and ‘Dickensy’; ‘Dickensian’ came in the decade after his death. Contradictions beset the many connotations of ‘Dickensian’: on one hand conviviality and good cheer; on the other oppression, injustice, poverty, and urban squalor. The meanings accruing around ‘Dickensian’ also have to do with his manner of writing, increasingly pejorative as Victorian fiction fell out of fashion. But Dickensian energy is something that always attracts. Dickens has been and always will be bigger than his books, as their spirits overflow into the conduits of communal affect.
6. ‘Your station in life’
Authors: Coulmas Florian
Published: February 2019

Social identity is to do with membership in groups that are horizontally and vertically structured, internally and in relation to each other. Taken together these groupings constitute a society. ‘ “Your station in life”: social identities in our time’ explains how with the growth of the service sector, class divisions started to become less distinct and were supplemented by ethnic divisions. Consequently, the general understanding of social class is changing and, as economic inequality rises, the issue of social stratification and identity remains topical. Group identities are relational, resulting from the inclusion of peers and the exclusion of others. Reducing individuals to a single identity as members of a group amounts to discrimination and stigmatization.
10. Who is behind the mask? Identity in literature
Authors: Coulmas Florian
Published: February 2019

In literature, we can find all aspects and dimensions of identity: identity through time, the mind–body problem, the identity of words and things, gender boundaries, identity crisis, divided loyalty, mistaken identity, split identity, and the demands of modernity for individuals to have a national, social, and gender identity. ‘Who is behind the mask? Identity in literature’ provides a range of illustrative examples. In addition to substantial questions of identity, the art of literature is also concerned with identity in two formal ways. Style expresses the identity of fictitious characters as well as of writers. Finally, by creating fictitious worlds, literature constructs identity puzzles in its own right.
Conclusion: The Identity of Identity
Authors: Coulmas Florian
Published: February 2019

The word ‘identity’ suggests immutability, self-sameness, and permanency, while in fact it does what other words also do: it changes its meaning, now so rapidly that it is hard to keep track. ‘Conclusion: the identity of identity’ concludes that, on the individual level, identities have become a matter of negotiating and, as the need to do so arises, renegotiating your place, your purpose, and your presentation in everyday life. On the collective level, identities are fuzzy sets rather than clearly delineated groups. Yet, the assertion of, search for, and preoccupation with, identity keeps growing and invading ever more spheres of life. There are no indications that the identity wave is flattening.
Introduction: an ‘Identity’ wave
Authors: Coulmas Florian
Published: February 2019

Talk about identity has become ubiquitous. The list of things that are said to have an identity is almost endless. The Introduction explains that identity is all about sameness and difference, but it’s not simple: ‘identity’ means different things to different people and in different disciplines. Identities are both things that must be explained and things that are invoked to explain. As the concept is understood nowadays, it is first of all rooted in the ideology of the French and American revolutions that celebrated the dignity and equality of the individual. This VSI does not concentrate on the different meanings of ‘identity’, but on why identity is important in so many different fields.
Garden History: A Very Short Introduction
Authors: Campbell Gordon
Published: February 2019

Gardens take many forms and have a variety of functions. They can serve as spaces of peace and tranquillity, a way to cultivate wildlife, or as places to develop agricultural resources. Globally, gardens have inspired, comforted, and sustained people, and many iconic gardens have inspired great artists, poets, musicians, and writers. Garden History: A Very Short Introduction embraces gardens in all their splendour, from parks and vegetable gardens to ornamental gardens, and takes the reader on a globe-trotting historical journey through iconic and cultural signposts of gardens from different regions and traditions. It concludes by looking to the future of the garden in terms of global warming and human innovation.
Britain
Authors: Campbell Gordon
Published: February 2019

‘Britain’ considers the garden history of the British Isles through the Renaissance to the present day. The burgeoning of English gardens in the 18th and 19th centuries often obliterated earlier gardens on the same sites, so earlier English gardens are usually known only from written and pictorial documentation, or from earthworks. The impact of key gardens and garden designers throughout this time are discussed: Salomon de Caus; Inigo Jones; William Shenstone’s The Leasowes; the great landscape designers Lancelot ‘Capability’ Brown and Humphry Repton; Sir Joseph Paxton; Hidcote Manor; Christopher Lloyd’s Great Dixter; Gertrude Jekyll’s Sissinghurst; Beth Chatto; and the Eden Project in Cornwall.
Trends in Incidence of Methicillin-resistant Staphylococcus aureus Bloodstream Infections Differ by Strain Type and Healthcare Exposure, United States, 2005–2013
Authors: See Isaac , Mu Yi , Albrecht Valerie , Karlsson Maria , Dumyati Ghinwa , Hardy Dwight J , Koeck Mackenzie , Lynfield Ruth , Nadle Joelle , Ray Susan M , Schaffner William , Kallen Alexander J
Published: February 2019

Background

Previous reports suggested that US methicillin-resistant Staphylococcus aureus (MRSA) strain epidemiology has changed since the rise of USA300 MRSA. We describe invasive MRSA trends by strain type.

Methods

Data came from 5 Centers for Disease Control and Prevention Emerging Infections Program sites conducting population-based surveillance and collecting isolates for invasive MRSA (ie, from normally sterile body sites), 2005–2013. MRSA bloodstream infection (BSI) incidence per 100 000 population was stratified by strain type and epidemiologic classification of healthcare exposures. Invasive USA100 vs USA300 case characteristics from 2013 were compared through logistic regression.

Results

From 2005 to 2013, USA100 incidence decreased most notably for hospital-onset (6.1 vs 0.9/100 000 persons, P < .0001) and healthcare-associated, community-onset (10.7 vs 4.9/100 000 persons, P < .0001) BSIs. USA300 incidence for hospital-onset BSIs also decreased (1.5 vs 0.6/100 000 persons, P < .0001). However, USA300 incidence did not significantly change for healthcare-associated, community-onset (3.9 vs 3.3/100 000 persons, P = .05) or community-associated BSIs (2.5 vs 2.4/100 000 persons, P = .19). Invasive MRSA was less likely to be USA300 in patients who were older (adjusted odds ratio [aOR], 0.97 per year [95% confidence interval {CI}, .96–.98]), previously hospitalized (aOR, 0.36 [95% CI, .24–.54]), or had central lines (aOR, 0.44 [95% CI, .27–.74]), and associated with USA300 in people who inject drugs (aOR, 4.58 [95% CI, 1.16–17.95]).

Conclusions

Most of the decline in MRSA BSIs was from decreases in USA100 BSI incidence. Prevention of USA300 MRSA BSIs in the community will be needed to further reduce burden from MRSA BSIs.
Intraluminal mesh erosion after prosthetic hiatoplasty: incidence, management, and outcomes
Authors: Sánchez-Pernaute Andrés , Pérez-Aguirre María Elia , Jiménez Aida Pérez , Campos Adriana Ruano , Muñoz Ana , Torres Antonio
Published: February 2019

The purpose of the present study was to analyze the incidence, presentation, and treatment of mesh erosion into the esophagus or stomach after mesh hiatoplasty for primary or recurrent hiatal hernia. The study is a single-institution, retrospective cohort study. From November 2005 to December 2016, 122 patients consecutively underwent mesh hiatoplasty in our department, 91 during a primary surgery and 31 for a surgical revision. Follow-up was complete for 74%. Six patients of this series were evaluated for mesh erosion. In all cases, the mesh employed was a dual-type circular one. The mean time from surgery to erosion diagnosis was 42 months (median time 46 months, interquartile range 64 months). Three patients were asymptomatic, 1 had dysphagia, 1 had reflux recurrence, and 1 presented with mediastinal perforation. The absolute erosion rate was 4.9%. For patients under surveillance, the erosion rate was 6.6%, or 1 case every 48 patient-years of follow-up. The erosion rate after primary surgery was 3% or 1/86 patient-years of follow-up, and after surgery for recurrent hernia recurrence was 16% or 1/29 patient-years of follow-up. The mesh was left in place in 2 asymptomatic cases and endoscopically removed in 2 cases. Two patients submitted to surgical removal of the mesh, and only one needed a limited gastroesophageal junction resection for a conversion to a Roux-en-Y gastric bypass. The patient with esophageal perforation submitted to mesh removal, drainage, and an anterior partial fundoplication. There was no mortality. Mesh erosion after hiatoplasty presents with a high rate, especially when hiatoplasty is performed during revisional antireflux surgery. Most patients can be managed conservatively, and endoscopic removal should be considered a first-line therapy.
Tracing the Impact of Public Health Interventions on HIV-1 Transmission in Portugal Using Molecular Epidemiology
Authors: Vasylyeva Tetyana I , du Plessis Louis , Pineda-Peña Andrea C , Kühnert Denise , Lemey Philippe , Vandamme Anne-Mieke , Gomes Perpétua , Camacho Ricardo J , Pybus Oliver G , Abecasis Ana B , Faria Nuno R
Published: February 2019

Background

Estimation of temporal changes in human immunodeficiency virus (HIV) transmission patterns can help to elucidate the impact of preventive strategies and public health policies.

Methods

Portuguese HIV-1 subtype B and G pol genetic sequences were appended to global reference data sets to identify country-specific transmission clades. Bayesian birth-death models were used to estimate subtype-specific effective reproductive numbers (Re). Discrete trait analysis (DTA) was used to quantify mixing among transmission groups.

Results

We identified 5 subtype B Portuguese clades (26–79 sequences) and a large monophyletic subtype G Portuguese clade (236 sequences). We estimated that major shifts in HIV-1 transmission occurred around 1999 (95% Bayesian credible interval [BCI], 1998–2000) and 2000 (95% BCI, 1998–2001) for subtypes B and G, respectively. For subtype B, Re dropped from 1.91 (95% BCI, 1.73–2.09) to 0.62 (95% BCI,.52–.72). For subtype G, Re decreased from 1.49 (95% BCI, 1.39–1.59) to 0.72 (95% BCI, .63–.8). The DTA suggests that people who inject drugs (PWID) and heterosexuals were the source of most (>80%) virus lineage transitions for subtypes G and B, respectively.

Conclusions

The estimated declines in Re coincide with the introduction of highly active antiretroviral therapy and the scale-up of harm reduction for PWID. Inferred transmission events across transmission groups emphasize the importance of prevention efforts for bridging populations.
Lurcherland: Poachers, Dogs and Animal Presence in English Life and Culture, c. 1831–1901
Authors: Ridgwell Stephen
Published: February 2019

In Victorian England poachers and dogs were subject to increasing levels of public interest and engagement. This article considers how their various interactions were represented across a range of printed and visual media and suggests that in establishing the poacher as a largely positive figure the dog had a vital role to play. If a number of other factors worked in favour of the poacher, not least the widespread dislike of the Game Laws, important in this process of legitimation was the poacher’s active link to the canine world. Though ambiguity always surrounded the poacher, and the dog was not always to be found on his side, more often than not it was. The development of this association casts an interesting light on the framing of human-animal relations in the nineteenth century, a critical moment for those concerned with the ‘animal turn’ and notions of non-human agency, and reveals how the dog was more than just the poacher’s ally in the un-official hunting field. As an urban-centred culture acquired a distinctly ruralist orientation, within the popular knowledge economy the idea of the poacher and his dog resonated across boundaries of class and geography. This in turn provides new evidence of how, at the level of culture, the more disreputable sides of life could be accommodated within a society that ostensibly prized respectability.
Kinetic ‘jets’ from fast-moving pulsars
Authors: Barkov Maxim V , Lyutikov Maxim , Klingler Noel , Bordas Pol
Published: February 2019

Some fast-moving pulsars, such as the Guitar and the Lighthouse, exhibit asymmetric non-thermal emission features that extend well beyond their ram pressure confined pulsar wind nebulae (PWNe). Based on our 3D relativistic simulations, we analytically explain these features as kinetically streaming pulsar wind particles that escaped into the interstellar medium (ISM) due to reconnection between the PWN and ISM magnetic fields. The structure of the reconnecting magnetic fields at the incoming and outgoing regions produces highly asymmetric magnetic bottles therefore and result in asymmetric extended features. For the features to become visible, the ISM magnetic field should be sufficiently high, BISM > 10 $\mu$G. We also discuss archival observations of PWNe displaying evidence of kinetic jets: the Dragonfly PWN (PSR J2021 + 3651), G327.1–1.1, and MSH 11–62, the latter two of which exhibit symmetric ‘snail eyes’ morphologies. We suggest that in those cases the pulsar is moving along the ambient magnetic field in a frisbee-type configuration.
The C-Band All-Sky Survey (C-BASS): constraining diffuse Galactic radio emission in the North Celestial Pole region
Authors: Dickinson C , Barr A , Chiang H C , Copley C , Grumitt R D P , Harper S E , Heilgendorff H M , Jew L R P , Jonas J L , Jones Michael E , Leahy J P , Leech J , Leitch E M , Muchovej S J C , Pearson T J , Peel M W , Readhead A C S , Sievers J , Stevenson M A , Taylor Angela C
Published: February 2019

The C-Band All-Sky Survey (C-BASS) is a high sensitivity all-sky radio survey at an angular resolution of 45 arcmin and a frequency of 4.7 GHz. We present a total intensity map of the North Celestial Pole (NCP) region of sky, above declination >+80°, which is limited by source confusion at a level of ≈0.6 mK rms. We apply the template-fitting (cross-correlation) technique to WMAP and Planck data, using the C-BASS map as the synchrotron template, to investigate the contribution of diffuse foreground emission at frequencies ∼20–40 GHz. We quantify the anomalous microwave emission (AME) that is correlated with far-infrared dust emission. The AME amplitude does not change significantly (${\lt }10\, {{\ \rm per\ cent}}$) when using the higher frequency C-BASS 4.7 GHz template instead of the traditional Haslam 408 MHz map as a tracer of synchrotron radiation. We measure template coefficients of 9.93 ± 0.35 and $9.52\pm 0.34\,$ K per unit τ353 when using the Haslam and C-BASS synchrotron templates, respectively. The AME contributes $55\pm 2\, \mu$K rms at 22.8 GHz and accounts for ${\approx } 60{{\ \rm per\ cent}}$ of the total foreground emission. Our results show that a harder (flatter spectrum) component of synchrotron emission is not dominant at frequencies ≳5 GHz; the best-fitting synchrotron temperature spectral index is β = −2.91 ± 0.04 from 4.7 to 22.8 GHz and β = −2.85 ± 0.14 from 22.8 to 44.1 GHz. Free–free emission is weak, contributing ${\approx } 7\, \mu$K rms (${\approx } 7{{\ \rm per\ cent}}$) at 22.8 GHz. The best explanation for the AME is still electric dipole emission from small spinning dust grains.