bluuebunny/crossref_metadata_2025 huggingface dataset:
Non-planar elasticae as optimal curves for the magnetic axis of stellarators
Authors: Pfefferlé D. , Gunderson L. , Hudson S. R. , Noakes L.
Published: September 2018

The problem of finding an optimal curve for the target magnetic axis of a stellarator is addressed. Euler-Lagrange equations are derived for finite length three-dimensional curves that extremise their bending energy while yielding fixed integrated torsion. The obvious translational and rotational symmetries are exploited to express solutions in a preferred cylindrical coordinate system in terms of elliptic Jacobi functions. These solution curves, which, up to similarity transformations, depend on three dimensionless parameters, do not necessarily close. Two closure conditions are obtained for the vertical and toroidal displacement (the radial coordinate being trivially periodic) to yield a countably infinite set of one-parameter families of closed non-planar curves. The behaviour of the integrated torsion (Twist of the Frenet frame), the Linking of the Frenet frame, and the Writhe of the solution curves are studied in light of the Călugăreanu theorem. A refreshed interpretation of Mercier's formula for the on-axis rotational transform of stellarator magnetic field-lines is proposed.
Adiabatic superconducting artificial neural network: Basic cells
Authors: Soloviev Igor I. , Schegolev Andrey E. , Klenov Nikolay V. , Bakurskiy Sergey V. , Kupriyanov Mikhail Yu. , Tereshonok Maxim V. , Shadrin Anton V. , Stolyarov Vasily S. , Golubov Alexander A.
Published: September 2018

We consider adiabatic superconducting cells operating as an artificial neuron and synapse of a multilayer perceptron (MLP). Their compact circuits contain just one and two Josephson junctions, respectively. While the signal is represented as magnetic flux, the proposed cells are inherently nonlinear and close-to-linear magnetic flux transformers. The neuron is capable of providing the one-shot calculation of sigmoid and hyperbolic tangent activation functions most commonly used in MLP. The synapse features both positive and negative signal transfer coefficients in the range ∼(−0.5,0.5). We briefly discuss implementation issues and further steps toward the multilayer adiabatic superconducting artificial neural network, which promises to be a compact and the most energy-efficient implementation of MLP.
Domain structure transition from two to three dimensions in tensile strained (100)/(001)-oriented epitaxial tetragonal PZT film
Authors: Ichinose Daichi , Shimizu Takao , Sakata Osami , Yamada Tomoaki , Funakubo Hiroshi
Published: September 2018

Pb(Zr0.05Ti0.95)O3 thin films of 30 nm thickness were epitaxially grown at 600 °C on (001) KTaO3 single crystal substrates by metal organic chemical vapor deposition. Films consist of the mixture of the a/c-domain composed of the c-domain with out-of-plane polarization and the a-domain with in-plane polarization and the a1/a2-domain formed by the combination of a-domains whose in-plane polar axes are orthogonal to each other. Films above the Curie temperature (Tc) of 550 °C were found to be under the in-plane tensile strain and transformed to a1/a2-domains at Curie temperature when the temperature decreased. This a1/a2-domain further changed to the mixture of the a/c-domain and a1/a2-domain below 350 °C. This indicated that the two-dimensional domain structures of the a1/a2-domain changed to three dimensional ones below Tc. Although the a/c-domain was induced to relax the strain, the a1/a2-domain was still unrelaxed. This is different from the widely investigated in-plane compressive strained films that have a one to three dimensional domain structure.
Atomic scale shot-noise using cryogenic MHz circuitry
Authors: Massee F. , Dong Q. , Cavanna A. , Jin Y. , Aprili M.
Published: September 2018

By implementing dedicated cryogenic circuitry operating in the MHz regime, we have developed a scanning tunneling microscope (STM) capable of conventional, low frequency (<10 kHz), microscopy as well spectroscopy and shot-noise detection at 1 MHz. After calibrating our AC circuit on a gold surface, we illustrate our capability to detect shot-noise at the atomic scale and at low currents (<1 nA) by simultaneously measuring the atomically resolved differential conductance and shot-noise on the high temperature superconductor Bi2Sr2CaCu2O8+x. We further show our direct sensitivity to the temperature of the tunneling electrons at low voltages. Our MHz circuitry opens up the possibility to study charge and correlation effects at the atomic scale in all materials accessible to STM.
Amplifier for scanning tunneling microscopy at MHz frequencies
Authors: Bastiaans K. M. , Benschop T. , Chatzopoulos D. , Cho D. , Dong Q. , Jin Y. , Allan M. P.
Published: September 2018

Conventional scanning tunneling microscopy (STM) is limited to a bandwidth of a few kHz around DC. Here, we develop, build, and test a novel amplifier circuit capable of measuring the tunneling current in the MHz regime while simultaneously performing conventional STM measurements. This is achieved with an amplifier circuit including a LC tank with a quality factor exceeding 600 and a home-built, low-noise high electron mobility transistor. The amplifier circuit functions while simultaneously scanning with atomic resolution in the tunneling regime, i.e., at junction resistances in the range of giga-ohms, and down towards point contact spectroscopy. To enable high signal-to-noise ratios and meet all technical requirements for the inclusion in a commercial low temperature, ultra-high vacuum STM, we use superconducting cross-wound inductors and choose materials and circuit elements with low heat load. We demonstrate the high performance of the amplifier by spatially mapping the Poissonian noise of tunneling electrons on an atomically clean Au(111) surface. We also show differential conductance spectroscopy measurements at 3 MHz, demonstrating superior performance over conventional spectroscopy techniques. Further, our technology could be used to perform impedance matched spin resonance and distinguish Majorana modes from more conventional edge states.
Controlling the ellipticity of attosecond pulses produced by laser irradiation of overdense plasmas
Authors: Blanco M. , Flores-Arias M. T. , Gonoskov A.
Published: September 2018

The interaction of high-intensity laser pulses and solid targets provides a promising way to create compact, tunable, and bright XUV attosecond sources that can become a unique tool for a variety of applications. However, it is important to control the polarization state of this XUV radiation and to do so in the most efficient regime of generation. Using the relativistic electronic spring (RES) model and particle-in-cell simulations, we show that the polarization state of the generated attosecond pulses can be tuned in a wide range of parameters by adjusting the polarization and/or the angle of incidence of the laser radiation. In particular, we demonstrate the possibility of producing circularly polarized attosecond pulses in a wide variety of setups.
Non-equilibrium x-ray spectroscopy using direct quantum dynamics
Authors: Northey T. , Duffield J. , Penfold T. J.
Published: September 2018

Advances in experimental methodology aligned with technological developments, such as 3rd generation light sources, X-ray Free Electron Lasers, and High Harmonic Generation, have led to a paradigm shift in the capability of X-ray spectroscopy to deliver high temporal and spectral resolution on an extremely broad range of samples in a wide array of different environments. Importantly, the complex nature and high information content of this class of techniques mean that detailed theoretical studies are often essential to provide a firm link between the spectroscopic observables and the underlying molecular structure and dynamics. In this paper, we present approaches for simulating dynamical processes in X-ray spectroscopy based upon on-the-fly quantum dynamics with a Gaussian basis set. We show that it is possible to provide a fully quantum description of X-ray spectra without the need of precomputing highly multidimensional potential energy surfaces. It is applied to study two different dynamical situations, namely, the core-hole lifetime dynamics of the water monomer and the dissociation of CF4+ recently studied using pump-probe X-ray spectroscopy. Our results compare favourably to previous experiments, while reducing the computational effort, providing the scope to apply them to larger systems.
Parent bending effects on nonadiabatic transition dynamics: Isotopomer-resolved imaging of photodissociation of CF3Br at two source temperatures
Authors: Li Fangfang , Ma Yujie , Liu Jiaxing , Wang Fengyan
Published: September 2018

Nonadiabatic transition between electronic states plays a critical role in the photodissociation of the CX3Y (X = H and F; Y = Cl, Br, and I) system, and the transition probability was considered to be closely related to the X–C–Y bending motion. Hereby the effect of F–C–Br bending vibration on the nonadiabatic transition dynamics is studied by time-sliced ion velocity imaging of Br(2P1/2,3/2) isotopomers produced from the photodissociation of title molecules at two source temperatures, 298 K and 473 K, respectively. At the photolysis wavelength 234 nm, the anisotropy parameter (β) of the Br(2P3/2) products decreases from 1.3 at 298 K to 0.9 at 473 K, while the β of Br(2P1/2) remains at almost 2 at two temperatures, indicating the significant effect of bending excitation on the ground channel. Two nonadiabatic dissociation pathways are suggested in the Br(2P3/2) channel. One of them is the parallel excitation from the ground state to the 3Q0 state in C3V symmetry, and then transition to the 1Q1 state via conical intersection, and the other is the perpendicular excitation to the 3A′ state in Cs symmetry and then decomposition along this state in the presence of the avoided crossing between 3A′ and 4A′ states. Closely related to the F–C–Br bending vibration of CF3Br is the latter transition.
Origin of focused laser irradiation-induced enhancement of perpendicular magnetic anisotropy in Pt/Co/Pt thin films investigated by spatially resolved x-ray absorption spectroscopy
Authors: Amemiya K. , Sakamaki M. , Kisielewski J. , Kurant Z. , Sveklo I. , Tekielak M. , Wawro A. , Maziewski A.
Published: September 2018

The origin of the focused single-pulse laser irradiation-induced changes in magnetic anisotropy of a Pt/Co/Pt film is investigated by the x-ray absorption near-edge structure and extended x-ray absorption fine structure techniques combined with the photoelectron emission microscope. A significant increase of the Co–Co bond length in both in-plane and out-of-plane directions is observed on the periphery of the laser spot, at which perpendicular magnetization appears. With increasing laser power density towards the center of the laser spot, anisotropic structural changes are observed accompanied by the reappearance of in-plane magnetization. The enhancement of perpendicular magnetization is attributed to the lattice expansion-induced magnetoelastic effect, while the in-plane compressive strain in the Co film is suggested to be the origin of the reappearance of in-plane magnetization at higher laser power densities.
Fully spherical stretchable silicon photodiodes array for simultaneous 360 imaging
Authors: Torres Sevilla Galo A. , Qaiser Nadeem , Cordero Marlon D. , Shaikh Sohail F. , Hussain Muhammad M.
Published: September 2018

Imaging is one of the important wonders of today's world. While everyday millions of snaps are taken, new advances like panoramic imaging have become increasingly popular. However, as of today an imaging system which can simultaneously capture images from all 360° viewpoints with a single sensor has not been achieved. Here, we show a physically flexible and stretchable version of arrayed silicon photodiodes made from low-cost bulk monocrystalline silicon (100) that can capture simultaneous omnidirectional images. The present report, with multiple wavelength detection, fast photoresponsivity, a wide viewing angle, selective aberration, and dynamic focusing enabled by 3D printed pneumatic actuators (note, today millions of image sensors can be integrated in mm2 area), overcomes previous demonstrations of only hemispherical photodetection capability. Such imaging capability will make unmanned air vehicles or self-driven cars safer, affordable augmented and virtual reality and more importantly, in-vivo biomedical imaging will be more effective.
Linewidth of the laser optical frequency comb with arbitrary temporal profile
Authors: Khurgin Jacob B. , Henry Nathan , Burghoff David , Hu Qing
Published: September 2018

For many applications, optical frequency combs (OFCs) require a high degree of temporal coherence (narrow linewidth). Commonly, OFCs are generated in nonlinear media from a monochromatic narrow linewidth laser source or from a mode-locked laser pulse, but in all the important mid-infrared (MIR) and terahertz (THz) regions of the spectrum, OFCs can be generated intrinsically by free-running quantum cascade lasers (QCLs) with high efficiency. These combs do not look like conventional OFCs as the phases of each mode are different, and in the temporal domain, OFCs are a seemingly random combination of amplitude- and phase-modulated signals rather than a short pulse. Despite this “pseudo-randomness,” the experimental evidence suggests that the linewidth of a QCL OFC is just as narrow as that of a QCL operating in a single mode. While universally acknowledged, this observation is seemingly not fully understood. In this work, we explicate this fact by deriving the expression for the Schawlow-Townes linewidth of QCL OFCs and offer a transparent physical interpretation based on the orthogonality of laser modes, indicating that despite their very different temporal profiles, MIR and THz QCL OFCs are just as good for most applications as any other OFCs.
Experimental and theoretical investigations on the optical and electrochemical properties of π-conjugated donor-acceptor-donor (DAD) compounds toward a universal model
Authors: Chochos Christos L. , Chávez Patricia , Bulut Ibrahim , Lévêque Patrick , Spanos Michael , Tatsi Elisavet , Katsouras Athanasios , Avgeropoulos Apostolos , Gregoriou Vasilis G. , Leclerc Nicolas
Published: September 2018

A series of nine (9) donor-acceptor-donor (DAD) π-conjugated small molecules were synthesized via palladium catalyzed Stille aromatic cross-coupling reactions by the combination of six (6) heterocycle building blocks (thiophene, furan, thiazole, 2,1,3-benzothiadiazole, 2,1,3-pyridinothiadiazole, thienothiadiazole) acting as electron donating (thiazole, furan, thiophene) and electron deficient (benzothiadiazole, pyridinethiadiazole, thienothiadiazole) units. These model compounds enable determining the correspondence between the theoretical and experimental optical and electrochemical properties for the first time, via Density Functional Theory (DFT), time-dependent DFT, UV-Vis spectroscopy, and cyclic voltammetry, accordingly. The obtained theoretical models can be utilized for the design and synthesis of new DAD structures with precise optical bandgaps, absorption maxima, and energy levels suitable for different optoelectronic applications.
Processing-induced strain glass states in a Ni49.5Ti50.5 shape memory alloy
Authors: Wheeler Robert W. , Smith Jesse , Ley Nathan A. , Giri Anit , Young Marcus L.
Published: September 2018

Shape memory alloys (SMAs) represent a revolutionary and innovative class of active materials which can provide potential solutions to many of today's engineering problems due to their compact form, high energy densities, and multifunctional capabilities. While many applications in the biomedical, aerospace, and automotive industries have already been investigated and realized for Nickel-Titanium (NiTi) based SMAs, the effects of restricting the ferroelastic transformation to nanosized domains is not well understood and the potential remains untapped. In binary NiTi, the martensitic transformation, which is characterized by long-range strain ordering (LRO), can be replaced with a strain glass transition, which consists of an LRO parent phase and a short-range strain ordered glassy phase. Such alloys have been named strain glass alloys (SGAs) due to the fact that they exhibit a glassy state which results from compositionally- or processing-induced strain. While SGAs do not exhibit a stress-free, temperature-induced macroscopic phase change, they still exhibit the strain recovery and actuation capabilities intrinsic to near equiatomic NiTi and other SMAs. It has been shown in the available literature that certain compositions, for example 51.5 at. % Nickel in binary NiTi, can create a strain glass; however, these compositionally-induced NiTi SGAs generally have transformation temperatures below 173 K and this will restrict their practical applications. In the present study, a new method for producing a strain glass phase in Ti-rich NiTi through sufficient plastic deformation via cold work is reported; the resulting SGA exhibits a temperature-induced ferroelastic recovery above room temperature. Additionally, the macroscopic actuation capabilities are improved when compared to both compositionally-induced SGAs and the base material due to the increased functional stresses of the SGA. To better understand the transition from an SMA to an SGA, Ni49.5Ti50.5 (at. %) rods were processed to several degrees of cold work and characterized via scanning and transmission electron microscopy, differential scanning calorimetry, thermomechanical testing, and synchrotron radiation x-ray diffraction. The experimental results indicate that twin size decreases with additional cold work and, around 45% thickness reduction, stress-free thermal cycling no longer results in a measurable phase transformation; however, mechanically-induced phase transformation is still possible, where fully recoverable strains in these SGAs were observed to be above 4.5% when loaded at room temperature and recovered at 150 °C.
Ultrafast light-induced softening of chalcogenide thin films above the rigidity percolation transition
Authors: Khan Pritam , Yadav Rajesh Kumar , Adarsh K. V.
Published: September 2018

Little is known about the role of network rigidity in light-induced structural rearrangements in network glasses due to a lack of supporting experiments and theories. In this article, we demonstrate for the first time the ultrafast structural rearrangements manifested as induced absorption (IA) over a broad spectral range in a-GexAs35-xSe65 thin films above the mean-field rigidity percolation transition, quantified by the mean coordination number ⟨r⟩ = 2.40. The IA spectrum arising from self-trapped excitons induced structural rearrangements by softening the glass network that strikingly reveals two relaxation mechanisms which differ by one order of magnitude. The fast kinetics of electron-lattice interaction occurs within 1 ps, exhibits a weak dependence on rigidity, and dominates in the sub-bandgap region. In a stark contrast, the slow kinetics is associated with the structural changes in the bandgap region and depends strongly on network rigidity. Our results further demonstrate that amplitude of IA scales a linear relationship with excitation fluence which provides a unique way to induce structural rearrangements in an over-coordinated network to exploit it for practical purposes. Our results modify the conventional concept of rigidity dependence of light-induced effects in network glasses, when excited with an ultrafast laser.
PAX5-ELN oncoprotein promotes multistep B-cell acute lymphoblastic leukemia in mice
Authors: Jamrog Laura , Chemin Guillaume , Fregona Vincent , Coster Lucie , Pasquet Marlène , Oudinet Chloé , Rouquié Nelly , Prade Naïs , Lagarde Stéphanie , Cresson Charlotte , Hébrard Sylvie , Nguyen Huu Ngoc Sa , Bousquet Marina , Quelen Cathy , Brousset Pierre , Mancini Stéphane J. C. , Delabesse Eric , Khamlichi Ahmed Amine , Gerby Bastien , Broccardo Cyril
Published: September 2018

Significance

Engineered mouse models of acute leukemia are critical to understanding the biological mechanisms by which a primary oncogene induces disease. While PAX5 fusion proteins are considered primary oncogenic events in B-ALL, their role in leukemia development is ill-known due to the lack of animal models. This report provides a novel and accurate in vivo model for B-ALL induced by PAX5-ELN fusion protein that establishes a preleukemic phase and recapitulates the key features of human disease, including acquired mutations in genes of the JAK/STAT and RAS/MAPK pathways. This study is of general interest, as it allows a better understanding of the biological mechanism by which an oncoprotein perturbs normal B-cell development and leads to pathological B-ALL.
Functionally specific optogenetic modulation in primate visual cortex
Authors: Chernov Mykyta M. , Friedman Robert M. , Chen Gang , Stoner Gene R. , Roe Anna Wang
Published: September 2018

Significance

Primate visual cortex is organized into columns that process different features of a visual scene, such as color, orientation preference, and ocular dominance. Until now, their small size has made it difficult to modulate them directly. Here, we report for the first time that focal targeting of light-sensitive ion channels (channelrhodopsins) in macaques using lentiviral vectors allows one to stimulate functional domains. We show that such targeted stimulation leads to selective activation of anatomically connected neighboring domains with similar function. Such a fine-scale optical stimulation approach is capable of mapping functionally specific domain-based neuronal networks. Its potential for linking such networks to optogenetic modulation of perception and behavior opens doors for developing targeted, domain-based neuroprosthetics.
Role of transcription complexes in the formation of the basal methylation pattern in early development
Authors: Greenfield Razi , Tabib Amalia , Keshet Ilana , Moss Joshua , Sabag Ofra , Goren Alon , Cedar Howard
Published: September 2018

Significance

This paper reveals the molecular logic for generating the basal methylation pattern in each individual following erasure of the gametic profile in the preimplantation embryo. The results show that transcription factors and the RNA polymerase complex play a major role in protecting recognized regions from de novo methylation by recruiting the H3K4 methylation machinery. Because methylation is stably maintained through development, this mechanism serves to perpetuate the activity state present in the early embryo. This model may also help explain how transient factors from the gametes may influence methylation patterns in the offspring and, thereby, contribute to intergenerational epigenetic inheritance.
SAR by kinetics for drug discovery in protein misfolding diseases
Authors: Chia Sean , Habchi Johnny , Michaels Thomas C. T. , Cohen Samuel I. A. , Linse Sara , Dobson Christopher M. , Knowles Tuomas P. J. , Vendruscolo Michele
Published: September 2018

Significance

Protein oligomers are increasingly recognized as the most cytotoxic forms of protein aggregates. It has been very challenging, however, to target these oligomers with therapeutic compounds, because of their dynamic and transient nature. To overcome this problem, we present here a “structure–kinetic-activity relationship” (SKAR) approach, which enables the discovery and systematic optimization of compounds that reduce the number of oligomers produced during an aggregation reaction. We illustrate this strategy for the amyloid beta peptide (Aβ), which is closely associated with Alzheimer’s disease, by developing a rhodanine compound capable of dramatically reducing the production of Aβ oligomers. As this strategy is general, it can be applied to oligomers of any protein.
Robust hydrophobic coating on glass surface by an atmospheric-pressure plasma jet for plasma-polymerisation of hexamethyldisiloxane conjugated with (3-aminopropyl) triethoxysilane
Authors: Hossain Md. Mokter , Trinh Quang Hung , Nguyen Duc Ba , Sudhakaran M. S. P. , Mok Young Sun
Published: September 2018

Plasma polymerisation of hexamethyldisiloxane (HMDSO) and (3-aminopropyl)triethoxysilane (APTES) was attempted to form a robust hydrophobic coating film on glass surface. Although HMDSO is a common precursor for generating hydrophobic surface, the HMDSO-polymerised thin film is poor in strength. For the purpose of achieving the mechanical robustness of the coating, APTES was used together with HMDSO. Plasma polymerisation was performed using a dielectric barrier discharge plasma jet by varying the ratio of the two precursors to find a suitable condition that would produce robust hydrophobic thin film. Various instrumental techniques were used to characterise the coating layer. As a result of the examination of the hydrophobicity through the water contact angle measurements and the robustness by the scratch tests, the most reasonable coating was achieved at the HMDSO/APTES ratio of 3/1, the voltage of 7 kV and the treatment time of 60 s, and at this condition the WCA was 143°.
Engineering mesenchymal stem cells to improve their exosome efficacy and yield for cell‐free therapy
Authors: Phan Jennifer , Kumar Priyadarsini , Hao Dake , Gao Kewa , Farmer Diana , Wang Aijun
Published: September 2018

Through traditional medicine, there were diseases and disorders that previously remained untreated or were simply thought to be incurable. Since the discovery of mesenchymal stem cells (MSCs), there has been a flurry of research to develop MSC‐based therapy for diseases and disorders. It is now well‐known that MSCs do not typically engraft after transplantation and exhibit their therapeutic effect via a paracrine mechanism. In addition to secretory proteins, MSCs also produce extracellular vesicles (EVs), membrane‐bound nanovesicles containing proteins, DNA and RNA. The secreted vesicles then interact with target cells and deliver their contents, imparting their ultimate therapeutic effect. Unlike the widely studied cancer cells, the yield of MSC‐exosomes is a limiting factor for large‐scale production for cell‐free therapies. Here we summarise potential approaches to increase the yield of such vesicles while maintaining or enhancing their efficacy by engineering the extracellular environment and intracellular components of MSCs.
Reviewing the relationship between social policy and the contemporary populist radical right: welfare chauvinism, welfare nation state and social citizenship
Authors: Ketola Markus , Nordensvard Johan
Published: September 2018

Whilst populism has a long-standing relationship with social policy, the recent emergence of radical right populism as a considerable political force across Europe and beyond compels us to think further about this relationship. The aim of this review essay is to bring together literature on populism, welfare chauvinism and social citizenship in order to highlight the role social policy plays in the rhetoric and political approach of the populist radical right. This essay reviews, how, by developing artificial distinctions between culturally homogeneous ‘people’ and corrupt ‘elite’, the populist radical right generates interpretations of social citizenship that confers social rights based on of cultural or ethnic belonging, rather than as a matter of right. By simplifying the nature of complex social policy problems, radical right populism further problematises the mainstream social policy agenda. Consequently, radical right populism will continue to present a significant challenge to progressive and inclusive social policy.
Genomic insights into chromatin reprogramming to totipotency in embryos
Authors: Ladstätter Sabrina , Tachibana Kikuë
Published: September 2018

The early embryo is the natural prototype for the acquisition of totipotency, which is the potential of a cell to produce a whole organism. Generation of a totipotent embryo involves chromatin reorganization and epigenetic reprogramming that alter DNA and histone modifications. Understanding embryonic chromatin architecture and how this is related to the epigenome and transcriptome will provide invaluable insights into cell fate decisions. Recently emerging low-input genomic assays allow the exploration of regulatory networks in the sparsely available mammalian embryo. Thus, the field of developmental biology is transitioning from microscopy to genome-wide chromatin descriptions. Ultimately, the prototype becomes a unique model for studying fundamental principles of development, epigenetic reprogramming, and cellular plasticity. In this review, we discuss chromatin reprogramming in the early mouse embryo, focusing on DNA methylation, chromatin accessibility, and higher-order chromatin structure.
Histone supply: Multitiered regulation ensures chromatin dynamics throughout the cell cycle
Authors: Mendiratta Shweta , Gatto Alberto , Almouzni Genevieve
Published: September 2018

As the building blocks of chromatin, histones are central to establish and maintain particular chromatin states associated with given cell fates. Importantly, histones exist as distinct variants whose expression and incorporation into chromatin are tightly regulated during the cell cycle. During S phase, specialized replicative histone variants ensure the bulk of the chromatinization of the duplicating genome. Other non-replicative histone variants deposited throughout the cell cycle at specific loci use pathways uncoupled from DNA synthesis. Here, we review the particular dynamics of expression, cellular transit, assembly, and disassembly of replicative and non-replicative forms of the histone H3. Beyond the role of histone variants in chromatin dynamics, we review our current knowledge concerning their distinct regulation to control their expression at different levels including transcription, posttranscriptional processing, and protein stability. In light of this unique regulation, we highlight situations where perturbations in histone balance may lead to cellular dysfunction and pathologies.
Cytokinetic rings mind the gap
Authors: Short Ben
Published: September 2018

Cells can rapidly repair breaks in the contractile actomyosin ring to ensure the timely completion of cytokinesis.
Urine-derived lymphocytes as a non-invasive measure of the bladder tumor immune microenvironment
Authors: Wong Yien Ning Sophia , Joshi Kroopa , Khetrapal Pramit , Ismail Mazlina , Reading James L. , Sunderland Mariana Werner , Georgiou Andrew , Furness Andrew J.S. , Ben Aissa Assma , Ghorani Ehsan , Oakes Theres , Uddin Imran , Tan Wei Shen , Feber Andrew , McGovern Ursula , Swanton Charles , Freeman Alex , Marafioti Teresa , Briggs Timothy P. , Kelly John D. , Powles Thomas , Peggs Karl S. , Chain Benjamin M. , Linch Mark D. , Quezada Sergio A.
Published: September 2018

Despite the advances in cancer immunotherapy, only a fraction of patients with bladder cancer exhibit responses to checkpoint blockade, highlighting a need to better understand drug resistance and identify rational immunotherapy combinations. However, accessibility to the tumor prior and during therapy is a major limitation in understanding the immune tumor microenvironment (TME). Herein, we identified urine-derived lymphocytes (UDLs) as a readily accessible source of T cells in 32 patients with muscle invasive bladder cancer (MIBC). We observed that effector CD8+ and CD4+ cells and regulatory T cells within the urine accurately map the immune checkpoint landscape and T cell receptor repertoire of the TME. Finally, an increased UDL count, specifically high expression of PD-1 (PD-1hi) on CD8+ at the time of cystectomy, was associated with a shorter recurrence-free survival. UDL analysis represents a dynamic liquid biopsy that is representative of the bladder immune TME that may be used to identify actionable immuno-oncology (IO) targets with potential prognostic value in MIBC.
Anoctamin 5/TMEM16E facilitates muscle precursor cell fusion
Authors: Whitlock Jarred M. , Yu Kuai , Cui Yuan Yuan , Hartzell H. Criss
Published: September 2018

Limb-girdle muscular dystrophy type 2L (LGMD2L) is a myopathy arising from mutations in ANO5; however, information about the contribution of ANO5 to muscle physiology is lacking. To explain the role of ANO5 in LGMD2L, we previously hypothesized that ANO5-mediated phospholipid scrambling facilitates cell–cell fusion of mononucleated muscle progenitor cells (MPCs), which is required for muscle repair. Here, we show that heterologous overexpression of ANO5 confers Ca2+-dependent phospholipid scrambling to HEK-293 cells and that scrambling is associated with the simultaneous development of a nonselective ionic current. MPCs isolated from adult Ano5−/− mice exhibit defective cell fusion in culture and produce muscle fibers with significantly fewer nuclei compared with controls. This defective fusion is associated with a decrease of Ca2+-dependent phosphatidylserine exposure on the surface of Ano5−/− MPCs and a decrease in the amplitude of Ca2+-dependent outwardly rectifying ionic currents. Viral introduction of ANO5 in Ano5−/− MPCs restores MPC fusion competence, ANO5-dependent phospholipid scrambling, and Ca2+-dependent outwardly rectifying ionic currents. ANO5-rescued MPCs produce myotubes having numbers of nuclei similar to wild-type controls. These data suggest that ANO5-mediated phospholipid scrambling or ionic currents play an important role in muscle repair.
Stable rationality of orbifold Fano 3-fold hypersurfaces
Authors: Okada Takuzo
Published: September 2018

We determine the rationality of very general quasi-smooth Fano33-fold weighted hypersurfaces completely and determine the stable rationality of them except for cubic33-folds. More precisely we prove that (i) very general Fano33-fold weighted hypersurfaces of index11or22are not stably rational except possibly for the cubic 3-folds, (ii) among the2727families of Fano 3-fold weighted hypersurfaces of index greater than22, very general members of77specific families are not stably rational, and the remaining2020families consist of rational varieties.
Trusses: Between braces and rings
Authors: Brzeziński Tomasz
Published: September 2018

In an attempt to understand the origins and the nature of the law binding two group operations together into a skew brace, introduced by Guarnieri and Vendramin as a non-Abelian version of the brace distributive law of Rump and Cedó, Jespers, and Okniński, the notion of a skew truss is proposed. A skew truss consists of a set with a group operation and a semigroup operation connected by a modified distributive law that interpolates between that of a ring and a brace. It is shown that a particular action and a cocycle characteristic of skew braces are already present in a skew truss; in fact the interpolating function is a

1
1

-cocycle, the bijecitivity of which indicates the existence of an operation that turns a truss into a brace. Furthermore, if the group structure in a two-sided truss is Abelian, then there is an associated ring—another feature characteristic of a two-sided brace. To characterize a morphism of trusses, a pith is defined as a particular subset of the domain consisting of subsets termed chambers, which contains the kernel of the morphism as a group homomorphism. In the case of both rings and braces piths coincide with kernels. In general the pith of a morphism is a subsemigroup of the domain and, if additional properties are satisfied, pith is an

N

+

{\mathbb N}_+

-graded semigroup. Finally, giving heed to ideas of Angiono, Galindo, and Vendramin, we linearize trusses and thus define Hopf trusses and study their properties, from which, in parallel to the set-theoretic case, some properties of Hopf braces are shown to follow.
Abl2 is recruited to ventral actin waves through cytoskeletal interactions to promote lamellipodium extension
Authors: Zhang Ke , Lyu Wanqing , Yu Ji , Koleske Anthony J.
Published: September 2018

Abl family nonreceptor tyrosine kinases regulate changes in cell shape and migration. Abl2 localizes to dynamic actin-rich protrusions, such as lamellipodia in fibroblasts and dendritic spines in neurons. Abl2 interactions with cortactin, an actin filament stabilizer, are crucial for the formation and stability of actin-rich structures, but Abl2:cortactin-positive structures have not been characterized with high spatiotemporal resolution in cells. Using total internal reflection fluorescence microscopy, we demonstrate that Abl2 colocalizes with cortactin at wave-like structures within lamellum and lamellipodium tips. Abl2 and cortactin within waves are focal and transient, extend to the outer edge of lamella, and serve as the base for lamellipodia protrusions. Abl2-positive foci colocalize with integrin β3 and paxillin, adhesive markers of the lamellum–lamellipodium interface. Cortactin-positive waves still form in Abl2 knockout cells, but the lamellipodium size is significantly reduced. This deficiency is restored following Abl2 reexpression. Complementation analyses revealed that the Abl2 C-terminal half, which contains domains that bind actin and microtubules, is necessary and sufficient for recruitment to the wave-like structures and to support normal lamellipodium size, while the kinase domain–containing N-terminal half does not impact lamellipodium size. Together, this work demonstrates that Abl2 is recruited with cortactin to actin waves through cytoskeletal interactions to promote lamellipodium extension.
Asterless is a Polo-like kinase 4 substrate that both activates and inhibits kinase activity depending on its phosphorylation state
Authors: Boese Cody J. , Nye Jonathan , Buster Daniel W. , McLamarrah Tiffany A. , Byrnes Amy E. , Slep Kevin C. , Rusan Nasser M. , Rogers Gregory C.
Published: September 2018

Centriole assembly initiates when Polo-like kinase 4 (Plk4) interacts with a centriole “targeting-factor.” In Drosophila, Asterless/Asl (Cep152 in humans) fulfills the targeting role. Interestingly, Asl also regulates Plk4 levels. The N-terminus of Asl (Asl-A; amino acids 1-374) binds Plk4 and promotes Plk4 self-destruction, although it is unclear how this is achieved. Moreover, Plk4 phosphorylates the Cep152 N-terminus, but the functional consequence is unknown. Here, we show that Plk4 phosphorylates Asl and mapped 13 phospho-residues in Asl-A. Nonphosphorylatable alanine (13A) and phosphomimetic (13PM) mutants did not alter Asl function, presumably because of the dominant role of the Asl C-terminus in Plk4 stabilization and centriolar targeting. To address how Asl-A phosphorylation specifically affects Plk4 regulation, we generated Asl-A fragment phospho-mutants and expressed them in cultured Drosophila cells. Asl-A-13A stimulated kinase activity by relieving Plk4 autoinhibition. In contrast, Asl-A-13PM inhibited Plk4 activity by a novel mechanism involving autophosphorylation of Plk4’s kinase domain. Thus, Asl-A’s phosphorylation state determines which of Asl-A’s two opposing effects are exerted on Plk4. Initially, nonphosphorylated Asl binds Plk4 and stimulates its kinase activity, but after Asl is phosphorylated, a negative-feedback mechanism suppresses Plk4 activity. This dual regulatory effect by Asl-A may limit Plk4 to bursts of activity that modulate centriole duplication.
Dunbar, Paul Laurence
Authors: Dudley David L.
Published: September 2018

Paul Laurence Dunbar, born in Dayton, Ohio, in 1872, became the first African American to make his living solely as a writer. When he died of tuberculosis in 1906, he was perhaps the most famous and best-loved black man in America. During a short but prolific career, Dunbar composed about five hundred poems, one hundred short stories, four novels, many essays, and song lyrics. His public performances of his own works were wildly popular, and generations of African Americans were raised knowing, often by heart, his best-loved poems.

In 1896, William Dean Howells, dean of American literary critics, hailed Dunbar’s work, but singled out the dialect poems for special praise. The public preferred them, too. For the decade that remained to him, Dunbar continued to write dialect poems, some of which seem to reinforce negative stereotypes of African Americans, and others that appear to romanticize the “good old days” of the antebellum South. On the other hand, Dunbar produced essays and poetry critical of America and the severe limits and indignities imposed on African Americans. Why would such a writer produce works so contradictory? This has been the crux of Dunbar studies almost from the time of his death. His critical reception reveals much about the taste and political views of subsequent generations of his readers and critics, who would do well to remember the enormous challenges facing Dunbar and all African American artists who strove to find their voices and make a living during those post-Reconstruction years, the “nadir” of the black experience in America.
Settler Colonialism in Asian North American Representation
Authors: Day Iyko
Published: September 2018

The study of settler colonialism has evolved from a nearly exclusive examination of the interplay of Indigeneity and white settler colonial domination to an engagement that has become attentive to questions of racialized migration. Because British settler colonies violently displaced Indigenous peoples without widespread exploitation of their labor, racialized migrant labor has played an important role in establishing and developing settler colonies, from the exploitation of enslaved and convict labor, to indentured and contract labor, and to contemporary iterations of guest and undocumented labor. The reliance on hyper-exploitable, deportable, or disposable classes of migrants has been an integral logic of settler colonialism in North America, rendering Indigenous communities even more vulnerable to dislocation, dispossession, and environmental harm. Asian North American cultural representation offers a rich site to explore settler colonial logics of land dispossession, resource extraction, relocation, urban redevelopment, and incarceration. In particular, Asian North American cultural production has often recycled settler colonial tropes that both denigrate and romanticize Indigenous cultures in claims for belonging that attempt to challenge the racial logics of civil, social, and political exclusion. In North America, the projection of a heroic “pioneer” identity aims to recover early Asian labor from historical obscurity by demonstrating its vital contributions to developing the settler nation. These expressions reinforce the value of Western civilization and industry over an empty, uncivilized, and unproductive Indigenous world. Asian American invocations of “local” identity in Hawai‘i similarly assert a romanticized identification with Indigenous cultures that obscures Asian Americans’ structural dominance and active role in the dispossession of Native Hawaiians. Alternatively, Asian North American cultural producers have also become strong voices in social and cultural movements to prioritize Indigenous self-determination, ecological protection, and decolonial anti-capitalism. Critical approaches to Asian North American representation have become increasingly attuned to reckoning with colonial complicity, exploring the ethics of responsibility, indebtedness, and solidarity with Indigenous communities.
The Chinese in West Indian Fiction
Authors: Lee-Loy Anne-Marie
Published: September 2018

Asians in the West Indies are primarily migrants and their descendants from either South Asia or China. The representation of the Chinese in West Indian fiction is integrally connected to the specific development of the region. Indeed, to consider the role that the Chinese play in West Indian fiction is to engage, more generally, in the act of imaginatively locating the West Indies. Despite the fact that numerically, they have always held a marginal status in the region, the Chinese are very much present in West Indian literary landscapes. The recurring representations of the Chinese and Chineseness in such fiction are intimately tied to locating the metaphorical and discursive contours of the West Indies and of West Indians. In this context, depictions of the Chinese in West Indian literary texts tend to follow three lines of representation: (1) defining the region as an exotic “other place”; (2) negotiating the boundaries of West Indian belonging; and (3) complicating settled narratives of West Indian identity.
Cultural and Creative Industries
Authors: Mayer Vicki
Published: September 2018

The critical study of cultural and creative industries involves the interrogation of the ways in which different social forces impact the production of culture, its forms, and its producers as inherently creative creatures. In historical terms, the notion of “the culture industry” may be traced to a series of postwar period theorists whose concerns reflected the industrialization of mass cultural forms and their attendant marketing across public and private spheres. For them, the key terms alienation and reification spoke to the negative impacts of an industrial cycle of production, distribution, and consumption, which controlled workers’ daily lives and distanced them from their own creative expressions. Fears of the culture industry drove a mass culture critique that led social scientists to address the structures of various media industries, the division of labor in the production of culture, and the hegemonic consent between government and culture industries in the military-industrial complex. The crisis of capitalism in the 1970s further directed critical scholars to theorize new dialectics of cultural production, its flexibilization via new communications technologies and transnational capital flows, as well as its capture via new property regimes. Reflecting government discourses for capital accumulation in a post-industrial economy, these theories have generally subsumed cultural industries into a creative economy composed of a variety of extra-industrial workers, consumers, and communicative agents. Although some social theorists have extended cultural industry critiques to the new conjuncture, more critical studies of creative industries focus on middle-range theories of power relations and contradictions within particular industrial sites and organizational settings. Work on immaterial labor, digital enclosures, and production cultures have developed the ways creative industries are both affective and effective structures for the temporal and spatial formation of individuals’ identities.