bluuebunny/crossref_metadata_2025 huggingface dataset:
A network model for polarization of political opinion
Authors: Higham Desmond J. , Mantzaris Alexander V.
Published: April 2020

We propose and study a simple model for the evolution of political opinion through a population. The model includes a nonlinear term that causes individuals with more extreme views to be less receptive to external influence. Such a term was suggested in 1981 by Cobb in the context of a scalar-valued diffusion equation, and recent empirical studies support this modeling assumption. Here, we use the same philosophy in a network-based model. This allows us to incorporate the pattern of pairwise social interactions present in the population. We show that the model can admit two distinct stable steady states. This bi-stability property is seen to support polarization and can also make the long-term behavior of the system extremely sensitive to the initial conditions and to the precise connectivity structure. Computational results are given to illustrate these effects.
Anomalous Nernst effect in Cox(MgO)1-x granular thin films
Authors: Sheng P. , Fujita T. , Mizuguchi M.
Published: April 2020

The anomalous Nernst effect (ANE) is investigated for 100 nm Cox(MgO)1-x granular films as a function of the Co volume fraction (x) changes. The results show that by slightly adding MgO into the Co matrix, the anomalous Nernst angle (θAN) can be largely enhanced more than three times compared with that of pure Co, which also results in the obvious change in ANE voltage. The transverse conductivity σXYAH vs the longitudinal conductivity σXX shows distinct linear behavior in three regimes, which indicates different anomalous Hall effect (AHE) mechanisms. By qualitative Mott-relation analysis, we found that the non-monotonic dependence of ANE on x is associated with the change in AHE mechanisms.
A method for the detection of hCG β in spent embryo culture medium based on multicolor fluorescence detection from microfluidic droplets
Authors: Chen Peilin , Sun Qing , Xiong Feng , Zhong Huixian , Yao Zhihong , Zeng Yong
Published: April 2020

The evaluation of embryo quality via human chorionic gonadotropin beta (hCG β) and other proteins secreted by embryos in a spent embryo culture medium (SECM) receives a close review in the field of assisted reproduction. However, accurate and quantitative detection of these trace proteins is still a challenge. In this study, a highly sensitive protein detection method using microfluidic droplets and multicolor fluorescence detection was developed and used to detect hCG β secreted by embryos in SECM. β-Galactosidase (β-Gal) was used to label hCG β and can catalyze the conversion of nonfluorescent substrate fluorescein di-β-d-galactopyranoside to produce fluorescein to amplify the signal strength. Compared with previous studies, the proposed method requires only a simple microfluidic chip and can eliminate false-positive signals generated by free β-Gal through simultaneous detection of fluorescence, which can ensure the accuracy of the results. The lower detection limit of hCG β was 0.1 pg/ml. Using the developed method, hCG β in SECM was successfully detected; the hCG β secreted by top-quality blastocysts was significantly higher than that of non-top-quality blastocysts and embryos that do not develop into blastocysts. The proposed method can be used to detect secretory proteins from embryos in SECM and has application value in the screening of other biomarkers.
A novel instrument for investigating the dynamic microstructure evolution of high temperature service materials up to 1150 °C in scanning electron microscope
Authors: Ma Jinyao , Lu Junxia , Tang Liang , Wang Jin , Sang Lijun , Zhang Yuefei , Zhang Ze
Published: April 2020

High temperature materials usually serve under extreme conditions. In order to ensure the safety and reliability of industrial application, it is very significant to clarify the microstructural evolution and mechanical properties at high temperature. The in situ experiment combining mechanical tensile testing and heating in the scanning electron microscope (SEM) is a feasible method to study the relationship between the microstructure, mechanical properties, and temperature. However, it was challenging to acquire images of high quality when the temperature exceeded 800 °C due to the effect of thermal electrons and the instability of loading conditions at high temperature. In this study, a mini-tensile apparatus was devised and installed in an ordinary SEM, which can achieve a stable loading of 0–2200 N and obtain high quality images in the temperature range of 1150 °C. A highly efficient heat source with multi-layer thermal insulation was designed to prevent the other parts of the apparatus from being affected by high temperature. A symmetrical tensile structure was developed to ensure that the region of interest was always within the field of view of the microscope during testing. Thermal electrons were suppressed to ensure that the sample can be clearly distinguished at 1150 °C. In order to ensure the testing reliability, standard carbon steel was used to calibrate the instrument. Finally, a Ni-based single crystal superalloy, as an example, was tested using this in situ tensile testing system at 1150 °C to verify the main functions and reliability of the apparatus.
Scaling-down and interfacial effect to break down the trade-off between thermal stability and crystallization speed of the Sb2Se films
Authors: Wang Tao , Lu Yegang , Li Yang
Published: April 2020

Phase change memory (PCM) has been one of the most potential technologies for in-memory computing and neuromorphic integrated systems. It requires phase-change memory scaling toward higher density for such applications. However, the scaling-down and interfacial impact in phase-change materials, which are the core of PCMs, are still unclear. In this paper, the phase transition properties and crystallization behavior of phase-change material Sb2Se were tuned intrinsically by reducing the thickness of the Sb2Se film and coverage of VO2. It is shown that the crystallization temperature increases from 209 °C to 224 °C, and 10-year data retention temperature enhances from 117 °C to 139 °C, as the thickness of the Sb2Se film decreases from 50 nm to 2 nm. The coverage of VO2 could improve the thermal stability and crystallization rate of the Sb2Se film obviously, especially for smaller thickness. The kinetic exponent obtained by the JMA model indicates that the crystallization mechanism varies with film thickness, which could tune the crystallization rate of the Sb2Se film. This study provides a practical solution for on-going optimizing phase-change properties in terms of size and interfacial effects.
Three-dimensional simulations of detonation propagation in circular tubes: Effects of jet initiation and wall reflection
Authors: Chen Weiqiang , Liang Jianhan , Cai Xiaodong , Mahmoudi Yasser
Published: April 2020

In the present work, using a high-resolution three-dimensional numerical analysis, the initiation and propagation mechanism of a detonation wave is studied in a circular tube with a hot jet initiation. The reactive Euler equations with a one-step two-species chemistry model are solved based on the structured adaptive mesh refinement technique. Influences of both a single hot jet and impinging double hot jets on the formation of the detonation wave are studied. For each case, the objective is to investigate the role of the tube wall on the initiation and propagation of the detonation wave. The result for both cases shows that the hot jet-induced bow shock forms a complex reflection structure in the circular tube. The reflection effect of the circular wall strengthens the shock and facilitates the formation of the Mach stem, which leads to the formation of the detonation wave. However, when the hot jet condition and the total area of jet hole remain the same, for the case of initiation using double hot jets, the reflection strength of the bow shocks weakens when the diameters of the hot jets become smaller. When using a single hot jet, the initiated detonation is overdriven and propagates in the two-headed mode. In this initiation mode, by increasing the inflow Mach number, a four-headed mode detonation front is formed, while in the case of impinging double hot jets, a four-headed mode detonation front is initiated directly.
The direct criterion of Newcomb for the ideal MHD stability of stepped-pressure stellarators
Authors: Glasser A. H.
Published: April 2020

A recent publication presents the theoretical basis for extending the Newcomb criterion for the ideal magnetohydrodynamic stability of a straight, circular cylindrical plasma to an axisymmetric toroidal plasma. This paper further extends the method to a nonaxisymmetric plasma with stellarator symmetry and toroidal periodicity.
Dynamics of a solid of nearly neutral buoyancy in cavity subjected to rotational vibrations
Authors: Schipitsyn Vitaliy , Kozlov Victor
Published: April 2020

The behavior of a cylindrical body in a horizontal annulus with a longitudinal partition filled with a viscous fluid and subject to high-frequency rotational oscillations is experimentally investigated. The experiments are performed with light and heavy bodies, the density of which is only slightly different from the density of the liquid. The frequency and the amplitude of vibration vary in the experiments. With an increase in the vibration intensity, the repulsion from the boundary and suspension of the light body near the upper boundary of the layer (the heavy one—near the bottom) is found. The repulsion force acts on a solid near the boundary independently from its density. It is shown that vibrational suspension of the body in the gravity field is not associated with inertial oscillations of the body relative to the fluid but is determined by shear oscillations of the liquid itself and viscous interaction of the solid with the cavity boundary.
Non-monotonic effect of mass loading on turbulence modulations in particle-laden channel flow
Authors: Zhou Tian , Zhao Lihao , Huang Weixi , Xu Chunxiao
Published: April 2020

The effect of mass loading on turbulence modulation in channel flows is investigated in two-way coupled direct numerical simulations with the Lagrangian point-particle method. We carried out the simulations of turbulent channel flows at Reτ = 180, and the particle mass loading ranges from 0 to 0.96 with a fixed Stokes number St = 30. The statistics show that the intensity of the streamwise velocity fluctuation augmented non-monotonically with the increase in mass loading. The maximum enhancement of the streamwise turbulence intensity observed at a mass-loading of ϕm = 0.75 is 60% greater than that of the unladen flow. However, the velocity fluctuations in the spanwise and wall-normal direction as well as the Reynolds shear stress are attenuated monotonically with mass loading. To better interpret the non-monotonic effect of mass loading on the streamwise turbulence intensity, we further examined the near-wall vortices and streaks and proposed two competitive mechanisms. First, we found that the near-wall vortices become fewer and weaker and the spacing between streaks become wider as ϕm increases, which results in the damping effect on the fluctuation of the streamwise velocity. Second, the vortex structures and the streaks become more organized and straightly aligned in the streamwise direction with an increase in the streak strength, which enhances the streamwise velocity fluctuations. In addition, we observed a non-monotonic change in turbulent kinetic energy transfer between particle and fluid phases. The statistics of energy budgets show that particles extract energy from the fluid phase at ϕm < 0.6 but transfers energy back to the fluid phase at ϕm > 0.75 in the stream-wise direction.
Ionization induced dynamic alignment of water
Authors: McCracken Gregory A. , Bucksbaum Philip H.
Published: April 2020

Two-body dissociation resulting from strong-field double ionization of water is investigated. Two distinct features are seen in the alignment of the fragment momenta with respect to the laser polarization. One feature shows alignment of the H–OH axis with the laser polarization, while the other indicates polarization alignment normal to the H–OH axis. By analyzing kinematic differences between the OH+/D+ and OD+/H+ channels of HOD, these two alignment features are shown to result from dissociation from different states in the dication. Only dissociation from one of these states has an alignment dependence consistent with predictions of sequential strong-field tunneling ionization models. The alignment dependence of dissociation from the other state can only be explained by dynamic alignment launched by the unbending of the molecule during ionization.
Electric field thermopower modulation analyses of the operation mechanism of transparent amorphous SnO2 thin-film transistor
Authors: Liang Dou-dou , Zhang Yu-qiao , Cho Hai Jun , Ohta Hiromichi
Published: April 2020

Transparent amorphous oxide semiconductors (TAOSs) based transparent thin-film transistors (TTFTs) with high field effect mobility (μFE) are essential for developing advanced flat panel displays. Among TAOSs, amorphous (a-) SnO2 has several advantages against current a-InGaZnO4 such as higher μFE and being indium-free. Although a-SnO2 TTFT has been demonstrated several times, the operation mechanism has not been clarified thus far due to the strong gas sensing characteristics of SnO2. Here we clarify the operation mechanism of a-SnO2 TTFT by electric field thermopower modulation analyses. We prepared a bottom-gate top-contact type TTFT using 4.2-nm-thick a-SnO2 as the channel without any surface passivation. The effective thickness of the conducting channel was ∼1.7 ± 0.4 nm in air and in vacuum, but a large threshold gate voltage shift occurred in different atmospheres; this is attributed to carrier depletion near at the top surface (∼2.5 nm) of the a-SnO2 due to its interaction with the gas molecules and the resulting shift in the Fermi energy. The present results would provide a fundamental design concept to develop a-SnO2 TTFT.
Coriolis force-based instability of a shear-thinning microchannel flow
Authors: Sengupta Saunak , Ghosh Sukhendu , Chakraborty Suman
Published: April 2020

The instability mechanism based on the Coriolis force, especially on a rapidly rotating portable device handling shear-thinning fluids such as blood, is of utmost importance for eventual detection of diseases by mixing with suitable reagents. Motivated by this proposition, this study renders a modal stability analysis of shear-thinning fluids in a rotating microchannel modeled by the Carreau rheological law. When a microchannel is engraved with a rotating compact disk-based device, the centrifugal force acts as the driving force that actuates the flow and the Coriolis force enhances the mixing process in a significantly short span by destabilizing the flow. An Orr–Sommerfeld–Squire analysis is performed to explore the role of these forces on the linear stability of a rotating shear-thinning flow. Reported results on shear-thinning flow with streamwise disturbances indicate that the critical Reynolds number for the flow transition with viscosity perturbation is nearly half of that of the critical value for the same without viscosity perturbation. In sharp contrast, the present analysis considering spanwise disturbances reveals that the critical Reynolds numbers with and without viscosity perturbation remain virtually unaltered under rotational effects. However, the viscosity variation has no significant influence on the Coriolis force-based instability. Numerical results confirm that a momentous destabilization is possible with the use of the Coriolis force via generating secondary flow inside the channel. Interestingly, the roll cells corresponding to the instabilities at lower time constants exhibit the existence of two distinct vortices, and the center of the stronger one is essentially settled toward the unstable “stratified” region. Moreover, for a higher value of the time constant, only one vortex occupies the entire channel. This, in turn, may turn out to be of fundamental importance in realizing new instability regimes facilitating efficient mixing in rotationally actuated fluidic devices deployed for biochemical analysis and medical diagnostics.
Response of a turbulent boundary layer to rapid freestream acceleration
Authors: Saavedra J. , Poggie J. , Paniagua G.
Published: April 2020

In a wide range of fluid machinery, a turbulent boundary layer can be exposed to rapid transients of the freestream conditions. A simplified model of the boundary layer response would provide valuable guidance in understanding these situations in multiple engineering applications. To this end, a turbulent boundary flow, subject to freestream acceleration, was explored through high-fidelity simulations and Reynolds-averaged Navier–Stokes calculations. Test cases were considered in which the flow over a flat plate accelerated from Mach 0.3 up to 0.6 over two time scales, 10 ms and 25 ms. Based on data from the calculations, the integral boundary layer momentum equation was simplified to propose a new reduced-order model capable of computing the evolution of the boundary layer under external flow transients. Given the initial boundary layer height, and the temporal evolution of the freestream pressure, velocity, and density, the model predicts the transient development of the boundary layer. With the transient boundary layer profile known, the temporal history of the skin friction and heat transfer can be predicted, taking advantage of standard shear stress correlations and the Reynolds analogy.
Portable intrinsic gradiometer for ultra-sensitive detection of magnetic gradient in unshielded environment
Authors: Zhang Rui , Mhaskar Rahul , Smith Ken , Prouty Mark
Published: April 2020

We demonstrate a portable all-optical intrinsic scalar magnetic gradiometer composed of miniaturized cesium vapor cells and vertical-cavity surface-emitting lasers (VCSELs). Two cells, with inner dimensions of 5 mm × 5 mm × 5 mm and separated by a baseline of 5 cm, are driven by one VCSEL, and the resulting Larmor precessions are probed by a second VCSEL through optical rotation. The off-resonant linearly polarized probe light interrogates two cells at the same time, and the output of the intrinsic gradiometer is proportional to the magnetic field gradient measured over the given baseline. This intrinsic gradiometer scheme has the advantage of avoiding added noise from combining two scalar magnetometers. We achieve a sensitivity better than 18 fT/cm/√Hz in the gradient measurement. Ultra-sensitive short-baseline magnetic gradiometers can potentially play an important role in many practical applications, such as nondestructive evaluation and unexploded ordnance detection. Another application of the gradiometer is for magnetocardiography (MCG) in an unshielded environment. Real-time MCG signals can be extracted from the raw gradiometer readings. The demonstrated gradiometer greatly simplifies the MCG setup and may lead to a ubiquitous MCG measurement in the future.
Sharp relaxation rates for plane waves of general reaction-diffusion models
Authors: Hadadifard Fazel , Stefanov Atanas G.
Published: April 2020

It is a well-known and classical result that spectrally stable traveling waves of a general reaction-diffusion system in one spatial dimension are asymptotically stable with exponential relaxation rates. In a series of works in the 1990s, Goodman [Trans. Am. Math. Soc. 311, 683 (1989)], Kapitula [Trans. Am. Math. Soc. 349, 1901 (1997)], and Xin [Commun. Partial Differ. Equations 17, 1889 (1992)] considered plane traveling waves for such systems and they have succeeded in showing asymptotic stability for such objects. Interestingly, the (estimates for the) relaxation rates that they have exhibited are all algebraic and dimension dependent. It was heuristically argued that as the spectral gap closes in dimensions n ≥ 2, algebraic rates are the best possible. In this paper, we revisit this issue. We rigorously calculate the sharp relaxation rates in L∞ based spaces, both for the asymptotic phase and the radiation terms. They are, indeed, algebraic, but about twice better than the best ones obtained in these early works although this can be mostly attributed to the inefficiencies of using Sobolev embeddings to control L∞ norms by high order L2 based Sobolev spaces. Finally, we explicitly construct the leading order profiles, both for the phase and for the radiation terms. Our approach relies on the method of scaling variables, as introduced in the work of Gallay and Wayne [Arch. Ration. Mech. Anal. 163, 209 (2002) and Gallay and Wayne, Philos. Trans. R. Soc. A 360, 2155 (2002)] and, in fact, provides sharp relaxation rates in a class of weighted L2 spaces as well.
Efficient Flow Synthesis of Human Antimicrobial Peptides
Authors: Albin John S. , Pentelute Bradley L.
Published: April 2020

Organisms from all kingdoms of life have evolved a vast array of peptidic natural products to defend against microbes. These are known collectively as antimicrobial peptides (AMPs) or host defence peptides, reflecting their abilities not only to directly kill microbes, but also to modulate host immune responses. Despite decades of investigation, AMPs have yet to live up to their promise as lead therapeutics, a reality that reflects, in part, our incomplete understanding of these diverse agents in their various physiological contexts. Towards improving our understanding of AMP biology and the ways in which this can be best leveraged for therapeutic development, we are interested in large-scale comparisons of the antimicrobial and immunological activities of human AMPs, an undertaking that requires an efficient workflow for AMP synthesis and subsequent characterization. We describe here the application of flow chemistry and reverse-phase flash chromatography to the generation of 43AMPs, approaches that, when combined, significantly expedite synthesis and purification, potentially facilitating more systematic approaches to downstream testing and engineering.
Dry and moist dynamics shape regional patterns of extreme precipitation sensitivity
Authors: Nie Ji , Dai Panxi , Sobel Adam H.
Published: April 2020

Responses of extreme precipitation to global warming are of great importance to society and ecosystems. Although observations and climate projections indicate a general intensification of extreme precipitation with warming on global scale, there are significant variations on the regional scale, mainly due to changes in the vertical motion associated with extreme precipitation. Here, we apply quasigeostrophic diagnostics on climate-model simulations to understand the changes in vertical motion, quantifying the roles of dry (large-scale adiabatic flow) and moist (small-scale convection) dynamics in shaping the regional patterns of extreme precipitation sensitivity (EPS). The dry component weakens in the subtropics but strengthens in the middle and high latitudes; the moist component accounts for the positive centers of EPS in the low latitudes and also contributes to the negative centers in the subtropics. A theoretical model depicts a nonlinear relationship between the diabatic heating feedback (α) and precipitable water, indicating high sensitivity ofα(thus, EPS) over climatological moist regions. The model also captures the change ofαdue to competing effects of increases in precipitable water and dry static stability under global warming. Thus, the dry/moist decomposition provides a quantitive and intuitive explanation of the main regional features of EPS.
Expanding the genetic code of the human hematopoietic system
Authors: Shao Sida , Koh Minseob , Schultz Peter G.
Published: April 2020

Significance

The ability to genetically incorporate noncanonical amino acids (ncAAs) into proteins in bacteria, yeast, mammalian cells, and multicellular organisms has provided useful tools to study and manipulate protein structure and function. Here, we report the development of a method to stably encode ncAAs in human hematopoietic stem cells (HSCs) and their differentiated progenies, using self-replicating plasmids derived from Epstein-Barr virus. We also demonstrate that once transplanted, these manipulated HSCs can give rise to the entire hematopoietic system encoded with ncAAs. The methods described here should be applicable to other progenitor cell populations and provide tools for the study of human proteins in vitro and in vivo.
Ultratough graphene–black phosphorus films
Authors: Zhou Tianzhu , Ni Hong , Wang Yanlei , Wu Chao , Zhang Hao , Zhang Jianqi , Tomsia Antoni P. , Jiang Lei , Cheng Qunfeng
Published: April 2020

Significance

This manuscript describes the functionalization of the graphene oxide (GO) nanosheets by black phosphorus (BP) nanosheets through P-O-C covalent bonding. Such a strategy reduces the voids in the lamellar graphene film and makes the graphene film much more compact, while at the same time improving the alignment degree of GO nanosheets. Equally important, the conjugated AD molecules improve the compactness of the graphene films and the alignment degree of rGO nanosheets via π-π stacking interaction between adjacent rGO nanosheets. As a result, the record high toughness of our graphene film was achieved along with excellent electrical conductivity. In addition, our tough graphene–black phosphorus films also exhibit high ambient stability and electromagnetic shielding performance.
Cell-autonomous expression of the acid hydrolase galactocerebrosidase
Authors: Mikulka Christina R. , Dearborn Joshua T. , Benitez Bruno A. , Strickland Amy , Liu Lin , Milbrandt Jeffrey , Sands Mark S.
Published: April 2020

Significance

Lysosomal storage disorders (LSDs) are one of the most prevalent inherited pediatric conditions. Although some LSDs were described over a century ago, we understand little about how specific cells contribute to pathogenesis. Most LSDs are caused by a lysosomal enzyme deficiency. Lysosomal enzymes can be secreted from one cell and correct neighboring cells (cross-correction). Cross-correction prevents cell-limited expression or deletion of lysosomal enzymes, making it impossible to determine the role of specific cells in LSDs. Here we describe a method to eliminate cross-correction while maintaining enzymatic function. We used this method to determine the role of specific cells (myelin-producing) in Krabbe disease. This same method could be used to determine the role of specific cells in most other LSDs.
Distinct modes of manipulation of rice auxin response factor OsARF17 by different plant RNA viruses for infection
Authors: Zhang Hehong , Li Lulu , He Yuqing , Qin Qingqing , Chen Changhai , Wei Zhongyan , Tan Xiaoxiang , Xie Kaili , Zhang Ruifang , Hong Gaojie , Li Jing , Li Junmin , Yan Chengqi , Yan Fei , Li Yi , Chen Jianping , Sun Zongtao
Published: April 2020

Significance

Auxin signaling plays essential roles in almost every aspect of plant growth and development. Auxin response factors (ARFs) are key transcriptional regulators of auxin signaling. However, it is not clear what roles ARF transcription factors may play in plant–pathogen, and specifically plant–virus, interactions. This study reveals that an ARF transcription factor is targeted by several independently evolved viral proteins of very different plant RNA viruses. These viral proteins impede the ARF activity in different ways, but in each case, these interactions benefit viral infection. These findings demonstrate that manipulation of the auxin signaling by viral proteins is a common pathogenicity strategy in plant RNA viruses.
Human settlement of East Polynesia earlier, incremental, and coincident with prolonged South Pacific drought
Authors: Sear David A. , Allen Melinda S. , Hassall Jonathan D. , Maloney Ashley E. , Langdon Peter G. , Morrison Alex E. , Henderson Andrew C. G. , Mackay Helen , Croudace Ian W. , Clarke Charlotte , Sachs Julian P. , Macdonald Georgiana , Chiverrell Richard C. , Leng Melanie J. , Cisneros-Dozal L. M. , Fonville Thierry , Pearson Emma
Published: April 2020

Significance

We combine indicators from lake sediments with archaeological records that identify an earlier and incremental arrival of humans in East Polynesia than indicated by current models. We use lake sediments to reconstruct a quantitative, multiproxy hydroclimate sequences from Vanuatu, Samoa, and the Southern Cook Islands and combine these with published data to show that the timing of human migration into East Polynesia coincided with a prolonged drought. We postulate this regional drought was a significant contributory factor in eastward exploration and subsequent colonization of the Southern Cook Islands and beyond. The return of wetter conditions in East Polynesia after c. AD 1150 supported subsequent colonization of other central islands and, eventually, migration into far eastern and South Polynesia.
Mapping the
cis
-regulatory architecture of the human retina reveals noncoding genetic variation in disease
Authors: Cherry Timothy J. , Yang Marty G. , Harmin David A. , Tao Peter , Timms Andrew E. , Bauwens Miriam , Allikmets Rando , Jones Evan M. , Chen Rui , De Baere Elfride , Greenberg Michael E.
Published: April 2020

The interplay of transcription factors and
cis
-regulatory elements (CREs) orchestrates the dynamic and diverse genetic programs that assemble the human central nervous system (CNS) during development and maintain its function throughout life. Genetic variation within CREs plays a central role in phenotypic variation in complex traits including the risk of developing disease. We took advantage of the retina, a well-characterized region of the CNS known to be affected by pathogenic variants in CREs, to establish a roadmap for characterizing regulatory variation in the human CNS. This comprehensive analysis of tissue-specific regulatory elements, transcription factor binding, and gene expression programs in three regions of the human visual system (retina, macula, and retinal pigment epithelium/choroid) reveals features of regulatory element evolution that shape tissue-specific gene expression programs and defines regulatory elements with the potential to contribute to Mendelian and complex disorders of human vision.
A dual effect of ursolic acid to the treatment of multiple sclerosis through both immunomodulation and direct remyelination
Authors: Zhang Yuan , Li Xing , Ciric Bogoljub , Curtis Mark T. , Chen Wan-Jun , Rostami Abdolmohamad , Zhang Guang-Xian
Published: April 2020

Significance

Current immunomodulatory therapies for multiple sclerosis (MS) can effectively inhibit autoimmune response, but largely fail to promote myelin repair. This therapeutic deficiency is due mainly to the failure of treatment to promote remyelination in the central nervous system (CNS). Here we show that ursolic acid (UA), a natural triterpenoid, in addition to its well-known antiinflammatory effect, also directly stimulates oligodendrocyte maturation and CNS myelin repair. Mechanisms of UA action involve induction of pro-myelinating neurotrophic factor in astrocytes by PPARγ/CREB signaling and regulation of myelin-related gene expression during oligodendrocyte maturation via PPARγ activation. Our data demonstrate that UA has great potential as an agent for MS, especially at the chronic-progressive stage, because of its capacity in both immunomodulation and neural repair.
Imposed thermal gradients and resultant residual stresses: Physical and numerical simulations
Authors: Mukherjee D. , Tewary U. , Kumar S. , Karagadde S. , Verma R. K. , Sambandam M. , Samajdar I.
Published: April 2020

In this study, physical simulations were carried out on High Strength Low Alloy (HSLA) steel specimens. Samples were heated above and below the austenite transformation temperature and then cooled at different rates. Thermal history and residual stress gradients were measured experimentally and simulated numerically. This involved finite element simulations, which solved the Fourier's heat conduction equation and also incorporated appropriate subroutines for phase transformations. The latter involved HETVAL, to quantify phase transformation, and USDFLD, to calculate the corresponding heat inputs. This manuscript not only established a similar pattern between the controlled experiments and the numerical simulations but also provided a quantitative perspective to residual stress gradients, as introduced by temperature gradients and by phase transformations, during thermomechanical processing.
A new cladding technology to bond aluminium on magnesium
Authors: Jin H. , Javaid A.
Published: April 2020

An in situ hot press bonding technology has been developed to clad aluminium on magnesium. Followed by regular hot rolling, magnesium sheets, covered by ductile and corrosion-resistant aluminium without detectable oxides in the interface, are produced. The new technology requires no welding, vacuum, protective atmosphere or barrier layer, and it makes good interfacial strength and rollability. Aluminium–magnesium intermetallic phases are formed along the clad–core interface at elevated temperatures. They are not detrimental under compression but may cause clad-core delamination in tensile strain. However, the tensile failure is more dependent on the formability of magnesium core than on the strength of interface.
Golgi-associated BICD adaptors couple ER membrane penetration and disassembly of a viral cargo
Authors: Spriggs Chelsey C. , Badieyan Somayesadat , Verhey Kristen J. , Cianfrocco Michael A. , Tsai Billy
Published: April 2020

During entry, viruses must navigate through the host endomembrane system, penetrate cellular membranes, and undergo capsid disassembly to reach an intracellular destination that supports infection. How these events are coordinated is unclear. Here, we reveal an unexpected function of a cellular motor adaptor that coordinates virus membrane penetration and disassembly. Polyomavirus SV40 traffics to the endoplasmic reticulum (ER) and penetrates a virus-induced structure in the ER membrane called “focus” to reach the cytosol, where it disassembles before nuclear entry to promote infection. We now demonstrate that the ER focus is constructed proximal to the Golgi-associated BICD2 and BICDR1 dynein motor adaptors; this juxtaposition enables the adaptors to directly bind to and disassemble SV40 upon arrival to the cytosol. Our findings demonstrate that positioning of the virus membrane penetration site couples two decisive infection events, cytosol arrival and disassembly, and suggest cargo remodeling as a novel function of dynein adaptors.
Dscam2 suppresses synaptic strength through a PI3K-dependent endosomal pathway
Authors: Odierna G. Lorenzo , Kerwin Sarah K. , Harris Lucy E. , Shin Grace Ji-eun , Lavidis Nickolas A. , Noakes Peter G. , Millard S. Sean
Published: April 2020

Dscam2 is a cell surface protein required for neuronal development in Drosophila; it can promote neural wiring through homophilic recognition that leads to either adhesion or repulsion between neurites. Here, we report that Dscam2 also plays a post-developmental role in suppressing synaptic strength. This function is dependent on one of two distinct extracellular isoforms of the protein and is autonomous to motor neurons. We link the PI3K enhancer, Centaurin gamma 1A, to the Dscam2-dependent regulation of synaptic strength and show that changes in phosphoinositide levels correlate with changes in endosomal compartments that have previously been associated with synaptic strength. Using transmission electron microscopy, we find an increase in synaptic vesicles at Dscam2 mutant active zones, providing a rationale for the increase in synaptic strength. Our study provides the first evidence that Dscam2 can regulate synaptic physiology and highlights how diverse roles of alternative protein isoforms can contribute to unique aspects of brain development and function.
Constitutive activity of dopamine receptor type 1 (D1R) increases CaV2.2 currents in PFC neurons
Authors: McCarthy Clara Inés , Chou-Freed Cambria , Rodríguez Silvia Susana , Yaneff Agustín , Davio Carlos , Raingo Jesica
Published: April 2020

Alterations in dopamine receptor type 1 (D1R) density are associated with cognitive deficits of aging and schizophrenia. In the prefrontal cortex (PFC), D1R plays a critical role in the regulation of working memory, which is impaired in these cognitive deficit states, but the cellular events triggered by changes in D1R expression remain unknown. A previous report demonstrated that interaction between voltage-gated calcium channel type 2.2 (CaV2.2) and D1R stimulates CaV2.2 postsynaptic surface location in medial PFC pyramidal neurons. Here, we show that in addition to the occurrence of the physical receptor-channel interaction, constitutive D1R activity mediates up-regulation of functional CaV2.2 surface density. We performed patch-clamp experiments on transfected HEK293T cells and wild-type C57BL/6 mouse brain slices, as well as imaging experiments and cAMP measurements. We found that D1R coexpression led to ∼60% increase in CaV2.2 currents in HEK293T cells. This effect was occluded by preincubation with a D1/D5R inverse agonist, chlorpromazine, and by replacing D1R with a D1R mutant lacking constitutive activity. Moreover, D1R-induced increase in CaV2.2 currents required basally active Gs protein, as well as D1R-CaV2.2 interaction. In mice, intraperitoneal administration of chlorpromazine reduced native CaV currents’ sensitivity to ω-conotoxin-GVIA and their size by ∼49% in layer V/VI pyramidal neurons from medial PFC, indicating a selective effect on CaV2.2. Additionally, we found that reducing D1/D5R constitutive activity correlates with a decrease in the agonist-induced D1/D5R inhibitory effect on native CaV currents. Our results could be interpreted as a stimulatory effect of D1R constitutive activity on the number of CaV2.2 channels available for dopamine-mediated modulation. Our results contribute to the understanding of the physiological role of D1R constitutive activity and may explain the noncanonical postsynaptic distribution of functional CaV2.2 in PFC neurons.
The geodynamo for non-geophysicists
Authors: Herrmann Friedrich , Vorbach Tobias
Published: April 2020

The geodynamo usually appears as a somewhat intimidating subject. Its understanding seems to require knowledge of the intricate theory of magnetohydrodynamics. The solution of the corresponding equations can only be achieved numerically. It seems to be a subject for the specialist. We show that one can understand the basics of the functioning of the geodynamo solely by using the well-known laws of electrodynamics. The topic is not only important for geophysicists. The same physics is the cause for the magnetic fields of Sun-like stars, of the very strong fields of neutron stars, and also of the cosmic magnetic fields.
Ising models of charge storage in multifile metallic nanopores
Authors: Zaboronsky A O , Kornyshev A A
Published: April 2020

Ising type models of charging of conductive nanopores with ions have already been proposed and investigated for single file cylindrical or single layer slit nanopores. In such pores, the state of ions, the coulombic interactions of which are exponentially screened by their images in pore walls, was named superionic. In the present work we extend the analysis of the superionic state to nanopores that can accommodate multiple rows of ions. By grouping multiple charges in the same row into ‘supercharges’, we map the arrangement of ions in polarised electrodes on a multi-row Ising model in an external field. We investigate one-, two- and three-row cases, which we solve exactly, using a purpose-built semi-numerical transfer matrix method. For pores of different radii, which can accommodate the corresponding number of ion rows, we calculate the dependence of the electrical capacitance and stored energy density on electrode potential. As in charging the single file pores, we find that in narrower pores higher energy densities can be achieved at low applied potentials, while wider pores perform better as the voltage is increased.
A resonant cavity method for measuring electrical permittivity in the
GHz region
Authors: Thompson Frank
Published: April 2020

Resonant cavity perturbation as a means to measuring permittivity has been used
since the early 1940s. It is attractive because it is non-contact,
non-destructive and experimentally simple. Only recently, however, has the cost
of a small analyser board become acceptably low that experiments can be carried
out in schools and colleges. Using the TE 1,0,1 cavity mode in a rectangular
cavity, measurements of permittivity for distilled water, methanol and PTFE in
the microwave region of 1 GHz are presented and these agree well with published
data. A granular sugar sample is also investigated to confirm measurements
carried out with a compact Lecher Line apparatus
Smartphone-based remote assessment of upper extremity function for multiple sclerosis using the Draw a Shape Test
Authors: Creagh A P , Simillion C , Scotland A , Lipsmeier F , Bernasconi C , Belachew S , van Beek J , Baker M , Gossens C , Lindemann M , De Vos M
Published: April 2020

Objective: Smartphone devices may enable out-of-clinic assessments in chronic neurological diseases. We describe the Draw a Shape (DaS) Test, a smartphone-based and remotely administered test of Upper Extremity (UE) function developed for people with multiple sclerosis (PwMS). This work introduces DaS-related features that characterise UE function and impairment, and aims to demonstrate how multivariate modelling of these metrics can reliably predict the 9-Hole Peg Test (9HPT), a clinician-administered UE assessment in PwMS.Approach: The DaS Test instructed PwMS and healthy controls (HC) to trace predefined shapes on a smartphone screen. A total of 93 subjects (HC,n= 22; PwMS,n= 71) contributed both dominant and non-dominant handed DaS tests. PwMS subjects were characterised as those with normal (nPwMS,n= 50) and abnormal UE function (aPwMS,n= 21) with respect to their average 9HPT time (≤ or > 22.7 (s), respectively).L1-regularization techniques, combined with linear least squares (OLS, IRLS), or non-linear support vector (SVR) or random forest (RFR) regression were investigated as functions to map relevant DaS features to 9HPT times.Main results: It was observed that average non-dominant handed 9HPT times were more accurately predicted by DaS features (r2= 0.41,P<0.05; MAE: 2.08 ± 0.34 (s)) than average dominant handed 9HPTs (r2= 0.39,P<0.05; MAE: 2.32 ± 0.43 (s)), using simple linear IRLS (P<0.01). Moreover, it was found that the Mean absolute error (MAE) in predicted 9HPTs was comparable to the variability of actual 9HPT times within HC, nPwMS and aPwMS groups respectively. The 9HPT however exhibited large heteroscedasticity resulting in less stable predictions of longer 9HPT times.Significance: This study demonstrates the potential of the smartphone-based DaS Test to reliably predict 9HPT times and remotely monitor UE function in PwMS.
An Active Flexure Compensation Method for LAMOST spectrograph based on BP-Neural Network
Authors: Huang Shuo , Zou Hua , Liu Tian-Jiao , Zhao Shi-Yu , Zhang Hang
Published: April 2020

The Large sky AreaMulti-Object fiber Spectroscopic Telescope (LAMOST) is a Chinese national scientific research facility operated by National Astronomical Observatories, Chinese Academy of Sciences (NAOC). The LAMOST survey for the Milky Way Galaxy and extra-galactic objects has been carried out for several years. The accuracies in measuring radial velocity are expected to be 5 km s−1 for the low resolution spectroscopic survey (R = 1800), and 1 km s−1 for the medium resolution mode. The stability of spectrograph is the main factor affecting the accuracies in measuring radial velocity, so an Active Flexure Compensation Method (AFCM) based on Back Propagation Neural Network (BPNN) is proposed in this paper. It utilizes a deep BP (4-layer, 5-layer etc.) model of thermal-induced flexure to periodically predict and apply flexure corrections by commanding the corresponding tilt and tip motions to the camera. The spectrograph camera system is adjusted so that the positions of these spots match those in a reference image. The simulated calibration of this compensation method analytically illustrates its performance on LAMOST spectrograph.
Assessing the performance of molecular gas clump identification algorithms
Authors: Li Chong , Wang Hong-Chi , Wu Yuan-Wei , Ma Yue-Hui , Lin Liang-Hao
Published: April 2020

The detection of clumps (cores) in molecular clouds is an important issue in sub-millimetre astronomy. However, the completeness of the identification and the accuracy of the returned parameters of the automated clump identification algorithms are still not clear. In this work, we test the performance and bias of the GaussClumps, ClumpFind, FellWalker, Reinhold, and Dendrograms algorithms in identifying simulated clumps. By designing the simulated clumps with various sizes, peak brightness, and crowdedness, we investigate the characteristics of the algorithms and their performance. In the aspect of detection completeness, FellWalker, Dendrograms, and GaussClumps are the first, second, and third best algorithms, respectively. The numbers of correct identifications of the six algorithms gradually increase as the size and signal-to-noise ratio (SNRs) of the simulated clumps increase and they decrease as the crowdedness increases. In the aspect of the accuracy of retrieved parameters, FellWalker and Dendrograms exhibit better performance than the other algorithms. The average deviations in clump parameters for all algorithms gradually increase as the size and SNR of clumps increase. Most of the algorithms except FellWalker exhibit significant deviation in extracting the total flux of clumps. Taken together, FellWalker, GaussClumps, and Dendrograms exhibit the best performance in detection completeness and extracting parameters. The deviation in virial parameter for the six algorithms is relatively low. When applying the six algorithms to the clump identification for the Rosette molecular cloud, ClumpFind1994, ClumpFind2006, GaussClumps, FellWalker, and Reinhold exhibit performance that is consistent with the results from the simulated test.
The Coude Echelle Spectrograph for the Lijiang 1.8m telescope
Authors: Wang Xiao-Li , Chang Liang , Wang Lei , Ji Hang-Xin , Xian Hao , Tang Zhen , Xin Yu-Xin , Wang Chuan-Jun , He Shou-Sheng , Zhang Ju-Jia , Lun Bao-Li , Wei Kai , Li Xi-Qi , Jiang Xiao-Jun , Wang Hui-Juan , Li Hong-Bin , Mao Ji-Rong
Published: April 2020

The Coude Echelle Spectrograph (CES) was originally mounted on Xinglong 2.16 m telescope in 1994. When the High Resolution Fiber-fed Spectrograph (HRS) was commissioned at Xinglong 2.16 m telescope, the red path of CES was moved to Lijiang 1.8 m telescope, following some redesign and reinstallation. The CES of Lijiang 1.8 m telescope has the spectral resolution (R = λ/Δλ) ranging from 20000 to 50000 corresponding to different slit widths. With a 2k × 2k PI CCD, CES has a wavelength coverage between 570 nm to 1030 nm. In particular, the resolution of 37000 at 0.5 mm slit corresponds to 1.3″ on the sky. The limiting magnitude is V = 11.5 with the use of the tip-tilt feedback system, and the S/N is about 40 for 1 hour exposure at 600 nm (R = 37000). During the installation of CES, the tip-tilt mirror technology had successfully fulfilled high precision guiding and tracking for high resolution spectral observation and significantly improved the observation efficiency.