bluuebunny/crossref_metadata_2025 huggingface dataset:
Serum Pharmacochemistry Analysis Combined with Network Pharmacology Approach to Investigate the Antiosteoporosis Effect of Xianlinggubao Capsule in vivo
Authors: Xu Yun-Hui , Sun Yi-Chun , Liu Jie , Li Hui-Xin , Huang Chun-Yue , Pang Yuan-Yuan , Wu Tong , Hu Xiao
Published: April 2021

Xianlinggubao capsule (XLGB) is a traditional Chinese medicine multi-component herbal prescription and has been widely used in osteoporosis (OP) treatment. However, the underlying anti-OP mechanisms of XLGB have not been fully studied. In this study, an ovariectomized rat model of OP was established. The OP rats were orally administrated with XLGB, and then the main absorbed components in serum sample were assessed based on liquid chromatography-tandem mass spectrometry (LC-MS/MS). Subsequently, the potential anti-OP markers in XLGB were screened based on a network pharmacology strategy. Molecular docking analysis was used for confirmation. LC-MS showed 22 absorbed components in the serum sample of OP rat with XLGB treatment. Network pharmacology and pathway analysis suggested 19 potential anti-OP markers in XLGB. According to molecular docking process, most of the potential markers displayed strong interactions with the 22 absorbed components mentioned above. Besides, an absorbed component–potential marker–pathway network was further established. In conclusion, our data suggested the possible mechanisms for XLGB in OP treatment, in which the “multicomponents, multitargets, and multipathways” participated. Our article provided possible direction for drug discovery in OP and could help for exploring novel application of XLGB in clinical setting.
Open systems in classical mechanics
Authors: Baez John C. , Weisbart David , Yassine Adam M.
Published: April 2021

Generalized span categories provide a framework for formalizing mathematical models of open systems in classical mechanics. We introduce categories LagSy and HamSy that, respectively, provide a categorical framework for the Lagrangian and Hamiltonian descriptions of open classical mechanical systems. The morphisms of LagSy and HamSy correspond to such open systems, and the composition of morphisms models the construction of systems from subsystems. The Legendre transformation gives rise to a functor from LagSy to HamSy that translates from the Lagrangian to the Hamiltonian perspective.
Investigation of stagnation layer dynamics of counterpropagating laser induced air plasmas: Numerical simulations vis-à-vis experimental observations
Authors: Kameswari D. P. S. L. , Guthikonda Nagaraju , Shiva S. Sai , Manikanta E. , Harsha S. Sree , Ikkurthi V. R. , Kiran P. Prem
Published: April 2021

The interaction and evolution dynamics of two counterpropagating shockwaves generated by two collinear laser induced air plasmas of equal and unequal energies are presented. The formation of a stagnation layer during the interaction of the shockwaves from the two plasma sources, namely, S1 and S2 separated by a distance of 4 mm, were studied over a duration of 30 μs, using two-dimensional FLASH radiation hydrodynamic code. The stagnation layer formed is observed to be “hard” in the case of interaction of equal energy sources, S1 = S2. While in the case of unequal energy sources with S2 > S1, the stagnation layer is observed to allow the propagation of energy. For both the cases of equal and unequal energy sources, a maximum increase in temperature at the stagnation layer by ∼1.5 and 1.9 times, respectively, is observed due to the interaction of the expanding plasmas around the stagnation layer. The density and pressure in the unequal interaction case at the stagnation layer is observed to be more than that of the ambient conditions by 4.9 and 19 times, respectively. A clear visualization of shock front of high energy plasma source traversing through that of a lower energy source leads to a channel formation, followed by a jet-let along the laser axis due to density drag. The evolution of interacting plasma is compared with that of the evolution of individual sources. The simulations were validated by the experimental observations giving a one-on-one mapping of the spatiotemporal evolution of plasma and shock front.
Real-time nuclear activation detectors for measuring neutron angular distributions at the National Ignition Facility (invited)
Authors: Bionta R. M. , Grim G. P. , Hahn K. D. , Hartouni E. P. , Henry E. A. , Khater H. Y. , Moore A. S. , Schlossberg D. J.
Published: April 2021

The Real Time Nuclear Activation Detector (RTNAD) array at NIF measures the distribution of 14 MeV neutrons emitted by deuterium-tritium (DT) fueled inertial confinement fusion implosions. The uniformity of the neutron distribution is an important indication of implosion symmetry and DT shell integrity. The array consists of 48 LaBr3(Ce) crystal gamma-ray spectrometers mounted outside the NIF target chamber, which continuously monitor the slow decay of the 909 keV gamma-ray line from activated 89Zr located in Zr cups surrounding each crystal. The measured decay rate dramatically increases during a DT implosion in proportion to the number of 14 MeV neutrons striking each Zr cup. The neutrons produce activated 89Zr through an (n, 2n) reaction on 90Zr, which is insensitive to low energy neutrons. The neutron flux along the detector line-of-sight at shot time is determined by extrapolating the fitted 909 keV decay curve back to shot time. Automatic analysis algorithms were developed to handle the non-stop data stream. The large number of detectors and the high statistical accuracy of the array enable the spherical harmonic modes of the neutron angular distribution to be measured up to L ≤ 4 to provide a better understanding of implosion dynamics. In addition, these data combined with measurements of the down-scattered neutrons can be used to derive fuel areal density distributions. This paper will describe the RTNAD hardware and analysis procedures.
Determining the position of a single spin relative to a metallic nanowire
Authors: da Silva Barbosa J. F. , Lee M. , Campagne-Ibarcq P. , Jamonneau P. , Kubo Y. , Pezzagna S. , Meijer J. , Teraji T. , Vion D. , Esteve D. , Heeres R. W. , Bertet P.
Published: April 2021

The nanoscale localization of individual paramagnetic defects near an electrical circuit is an important step for realizing hybrid quantum devices with strong spin-microwave photon coupling. Here, we fabricate an array of individual nitrogen vacancy (NV) centers in diamond near a metallic nanowire deposited on top of the substrate. We determine the relative position of each NV center with ∼10 nm accuracy, using it as a vector magnetometer to measure the field generated by passing a DC through the wire.
Toward accurate electronic, optical, and vibrational properties of hexagonal Si, Ge, and Si1−xGex alloys from first-principle simulations
Authors: Bao Nanyun , Guo Fangyu , Kang Dongdong , Feng Yexin , Wang Han , Dai Jiayu
Published: April 2021

A new hexagonal phase of Si1−xGex alloys have been successfully synthesized through efforts in recent reports. Utilizing the combined first-principle calculations and special quasi-random model, we precisely investigated the structural, electronic, optical, and vibrational properties of hexagonal Si and Ge and disordered hexagonal Si1−xGex random alloys. We found a large negative deviation between the calculated lattice constants within the revised Perdew–Burke–Ernzerhof for solids functional and the linear fitting results. The electronic structures obtained by using the Tran–Blaha modified Becke–Johnson exchange potential confirm that hexagonal Si1−xGex (x > 0.625) alloys present direct bandgaps. Through solving the Bethe–Salpeter equation, the linear optical spectra of hexagonal Si and Ge are demonstrated. We reveal that the peaks of complex dielectric functions are redshifted with the addition of Ge atoms. Also, the real and imaginary parts exhibit strong anisotropy, which makes hexagonal Si1−xGex alloys potentially useful as nonlinear crystals. The transition is allowed in the infrared region for the hexagonal Si1−xGex (x > 0.625) alloys, and the linear optical spectra can be continuously tuned over a wide range of frequency with Ge addition in the infrared region. Furthermore, density-functional perturbation theory calculations were carried out to predict the off-resonance Raman activity. The results suggest that the vibrational modes of the Si–Si bond exhibit a strong dependency on the compositions, which provides a useful way to identify the most probable atomic configurations of hexagonal Si1–xGex alloys in future experiments.
Influence of a plasma-treated nutrient solution containing 2,4-dichlorobenzoic acid on the growth of cucumber in a hydroponic system
Authors: Takahashi Katsuyuki , Kawamura Shuhei , Takada Ryosuke , Takaki Koichi , Satta Naoya , Fujio Takuya
Published: April 2021

Allelochemicals are organic compounds exuded from the roots of plants, which have autotoxic effects on plant growth. In this study, the decomposition of 2,4-dichlorobenzoic acid (DCBA), an allelochemical of cucumber, by plasma generated in an air bubble in solution is examined, and the influence of plasma treatment of the solution on cucumber growth in a hydroponics system is investigated. Air gas is injected into water through a vertically positioned glass tube, into which a high-voltage wire electrode is placed to generate plasma. The concentration of DCBA decreases and the concentration of chloride ion produced by the dichlorination of DCBA increases with increasing discharge treatment time. Consequently, most DCBA has decomposed after 24 h of treatment. The discharge-treated solution is used as a nutrient solution for cultivating cucumber plants in a rockwool hydroponic system. The results show that the growth of most plants is inhibited by adding DCBA, as well as by the decrease in pH during discharge treatment; in contrast, plants subjected to discharge treatment with pH adjustment grow healthily.
Phase relations and thermoelasticity of magnesium silicide at high pressure and temperature
Authors: Gaida Nico Alexander , Niwa Ken , Sasaki Takuya , Hasegawa Masashi
Published: April 2021

Within the exploration of sustainable and functional materials, narrow bandgap magnesium silicide semiconductors have gained growing interest. Intriguingly, squeezing silicides to extreme pressures and exposing them to non-ambient temperatures proves fruitful to study the structural behavior, tune the electronic structure, or discover novel phases. Herein, structural changes and thermoelastic characteristics of magnesium silicides were probed with synchrotron x-ray diffraction techniques using the laser-heated diamond anvil cell and large volume press at high pressure and temperature and temperature-dependent synchrotron powder diffraction. Probing the ambient phase of Mg2Si (anti-CaF2-type Mg2Si, space group: Fm3¯m) at static pressures of giga-Pascals possibly unveiled the transformation to metastable orthorhombic anti-PbCl2-type Mg2Si (Pnma). Interestingly, heating under pressures introduced the decomposition of Mg2Si to hexagonal Mg9Si5 (P63) and minor Mg. Using equations of state (EoS), which relate pressure to volume, the bulk moduli of anti-CaF2-type Mg2Si, anti-PbCl2-type Mg2Si, and Mg9Si5 were determined to be B0 = 47(2) GPa, B0 ≈ 72(5) GPa, and B0 = 58(3) GPa, respectively. Employing a high-temperature EoS to the P–V–T data of anti-CaF2-type Mg2Si provided its thermoelastic parameters: BT0 = 46(3) GPa, B′T0 = 6.1(8), and (∂BT0/∂T)P = −0.013(4) GPa K−1. At atmospheric pressure, anti-CaF2-type Mg2Si kept stable at T = 133–723 K, whereas Mg9Si5 transformed to anti-CaF2-type Mg2Si and Si above T ≥ 530 K. This temperature stability may indicate the potential of Mg9Si5 as a mid-temperature thermoelectric material, as suggested from previous first-principles calculations. Within this realm, thermal models were applied, yielding thermal expansion coefficients of both silicides together with estimations of their Grüneisen parameter and Debye temperature.
Validating fewest-switches surface hopping in the presence of laser fields
Authors: Heindl Moritz , González Leticia
Published: April 2021

The capability of fewest-switches surface hopping (FSSH) to describe non-adiabatic dynamics under explicit excitation with external fields is evaluated. Different FSSH parameters are benchmarked against multi-configurational time dependent Hartree (MCTDH) reference calculations using SO2 and 2-thiocytosine as model, yet realistic, molecular systems. Qualitatively, FSSH is able to reproduce the trends in the MCTDH dynamics with (also without) an explicit external field; however, no set of FSSH parameters is ideal. The adequate treatment of the overcoherence in FSSH is revealed as the driving factor to improve the description of the excitation process with respect to the MCTDH reference. Here, two corrections were tested: the augmented-FSSH (AFSSH) correction and the energy-based decoherence correction. A dependence on the employed basis is detected in AFSSH, performing better when spin–orbit and external laser field couplings are treated as off-diagonal elements instead of projecting them onto the diagonal of the Hamilton operator. In the presence of an electric field, the excited state dynamics was found to depend strongly on the vector used to rescale the kinetic energy along after a transition between surfaces. For SO2, recurrence of the excited wave packet throughout the duration of the applied laser pulse is observed for laser pulses (>100 fs), resulting in additional interferences missed by FSSH and only visible in variational multi-configurational Gaussian when utilizing a large number of Gaussian basis functions. This feature vanishes when going toward larger molecules, such as 2-thiocytosine, where this effect is barely visible in a laser pulse 200 fs long.
Flower pollination algorithm-based I/Q phase imbalance compensation strategy
Authors: Meng Jie , Wang Houjun , Ye Peng , Zhao Yu , Zeng Hao , Guo Lianping
Published: April 2021

For wideband receiver systems, it is challenging to compensate the in-phase/quadrature (I/Q) phase mismatch by traditional methods, especially with a time delay deviation (TDD) between the I/Q channels. Considering the above situation, this paper proposes a full-scale I/Q phase imbalance model concerning TDD. The model divides phase mismatch into two parts, i.e., the linear phase (LP) part and the nonlinear phase part, and compensates each part with the corresponding compensation module separately. The design strategy of the compensation module is innovatively transformed into a constrained nonlinear optimization problem, and a metaheuristic algorithm, the flower pollination algorithm (FPA), is utilized to be the optimizer. The results of the contrast simulation with the LP elimination method show the efficiency of the proposed method. In addition, the superiority of the FPA-based structure is verified by comparing with other metaheuristic algorithms, the artificial bee colony technique, the bat algorithm, and the differential evolution algorithm, in terms of the compensation accuracy, algorithm stability, runtime consumption, and convergence performance. Ultimately, the image rejection ratio improvement on the actual platform after compensation is measured, which validates the proposed compensation structure and the corresponding optimization method practically, and the FPA is still the best choice among the competent optimizers.
Non-Fermi liquid behavior and signature of Griffiths phase in Ni–Cr binary alloy
Authors: Vishvakarma Sonu , Srinivas V.
Published: April 2021

Detailed magnetic, electrical, and thermal property measurements have been carried out on Ni100−xCrx binary alloys, mainly to study the effect of Cr. The following points emerge from this study: with the increase in Cr concentration, magnetic moment and Curie temperature linearly decreased and the ferromagnetic order is completely suppressed at the critical concentration (xcr ≈ 12.16 ± 0.03). The Rhodes–Wohlfarth ratio increases as the concentration approaches xcr, suggesting a weak itinerant ferromagnetic character of NiCr compositions (x < xcr). Analysis of low-temperature electrical resistivity and specific heat data suggests that the spin fluctuation’s contribution increases and the Fermi-liquid behavior breaks down as the concentration approaches xcr. For x ∼ xcr, the dc susceptibility χ(T) deviates from the Curie–Weiss law reminiscent to that of the Griffiths phase. The low-temperature magnetic isotherms of Ni–Cr follow power law, M(H)=M0+dλHλ, and the non-universal exponent (λ) shows a minimum at xcr ∼ 12. Further, temperature dependence of magnetization studies also support the presence of the quantum Griffiths phase, similar to that reported in the Ni–V alloy system. The temperature dependencies of the electrical resistivity, magnetization, and specific heat follow the theoretical predictions of a quantum critical point within experimental uncertainties.
A non-local fluid closure for modeling cyclotron resonance in collisionless magnetized plasmas
Authors: Jikei Taiki , Amano Takanobu
Published: April 2021

A fluid description for collisionless magnetized plasmas that takes into account the effect of cyclotron resonance has been developed. Following the same approach as the Landau fluid closure, the heat flux components associated with transverse electromagnetic fluctuations are approximated by a linear combination of lower-order moments in wavenumber space. The closure successfully reproduces the linear cyclotron resonance for electromagnetic waves propagating parallel to the ambient magnetic field. In the presence of finite temperature anisotropy, the model gives approximately correct prediction for an instability destabilized via the cyclotron resonance. A nonlinear simulation demonstrates the wave growth consistent with the linear theory followed by the reduction of initial anisotropy, and finally, the saturation of the instability. The isotropization may be understood in terms of quasilinear theory, which is developed within the framework of the fluid model but very similar to its fully kinetic counterpart. The result indicates that both linear and nonlinear collisionless plasma responses are approximately incorporated in the fluid model.
Overcoming finite-size effects in electronic structure simulations at extreme conditions
Authors: Dornheim Tobias , Vorberger Jan
Published: April 2021

Ab initio quantum Monte Carlo methods, in principle, allow for the calculation of exact properties of correlated many-electron systems but are, in general, limited to the simulation of a finite number of electrons N under periodic boundary conditions. Therefore, an accurate theory of finite-size effects is indispensable to bridge the gap to realistic applications in the thermodynamic limit. In this work, we revisit the uniform electron gas at finite temperature, as it is relevant to contemporary research, e.g., in the field of warm dense matter. In particular, we present a new scheme to eliminate finite-size effects both in the static structure factor S(q) and in the interaction energy v, which is based on the density response formalism. We demonstrate that this method often allows us to obtain v in the thermodynamic limit within a relative accuracy of ∼0.2% from as few as N = 4 electrons without any empirical choices or knowledge of results for other values of N. Finally, we evaluate the applicability of our method upon increasing the density parameter rs and decreasing the temperature T.
Coordination isomerism in spin crossover (SCO) materials
Authors: Cuza Emmelyne , Motei Rachid , Setifi Fatima , Bentama Abdeslem , Gómez-García Carlos J. , Triki Smail
Published: April 2021

A new series of three spin crossover (SCO) Fe(II) complexes based on a cyanocarbanion and on the neutral quinolin-8-amine (aqin) ligands, [Fe(aqin)2(tcnsme)2] (1), [Fe(aqin)2(tcnset)2] (2), and [Fe(aqin)2(tcnspr)2] (3), has been studied. The three complexes display similar molecular structures consisting of discrete [Fe(aqin)2(tcnsR)2] complexes [R = Me (1), Et (2), and Pr (3)]. Infrared spectroscopy and magnetic studies, performed on the three complexes, revealed the presence of similar SCO behaviors which strongly differ by their transition temperatures [234 K (1) < 266 K (2) < 360 K (3)]. The increase of the transition temperatures when passing from 1 to 3 may be explained by electronic and packing effects. Thus, when passing from Me (1) to Et (2) and Pr (3), the electron donor effect increases, resulting in an increase of the ligand field and, accordingly, in an increase of the transition temperature. On the other side, examination of the different coordination modes of the cyanocarbanions in the three complexes clearly reveals the crucial role of these coordination modes on the crystal packing and, therefore, on the transition temperature. We can, therefore, attribute the important increase of the transition temperature from complexes 1 to 3 to both effects: the electron donor character of the alkyl groups and the packing effects of the versatile cycnocarbanion ligands.
Vibration reduction during milling of highly flexible workpieces using active workpiece holder system
Authors: Hong T. H. , Lee J. H. , Seo C. H. , Kim K. H. , Kim H. Y.
Published: April 2021

The milling of highly flexible workpieces, such as thin-walled structures used in turbine blades, aerospace equipment, and jet engine compressors, requires vibration compensation to improve the quality of the workpiece surface. Vibration can be reduced by selecting appropriate cutting parameters. However, this approach reduces system productivity. This paper presents an active workpiece holder that controls the vibration of general computer numerical control machine tools. The proposed holder, which comprises a flexible guide mechanism, driver, and sensor, measures vibration and actively controls it using piezoactuators. A high-rigidity flexure mechanism was designed for the holder, and finite element method simulation and modal analysis were performed. Finally, the proposed system was fabricated, and experimental verification indicated that the system reduced vibration. The surface quality obtained using the controlled system was ∼50% better than that obtained using the uncontrolled system.
Out-of-plane magnetization oscillation in spin Hall device assisted by field-like torque
Authors: Taniguchi Tomohiro
Published: April 2021

An excitation of a large-amplitude out-of-plane magnetization oscillation in a ferromagnet by the spin Hall effect is of great interest for practical applications such as microwave generators and neuromorphic computing. However, both experimental and theoretical works have revealed that only small-amplitude oscillation around an in-plane easy axis can be excited via the spin Hall effect. Here, we propose that an out-of-plane oscillation can be excited due to an assistance of field-like torque. We focus on an in-plane magnetized ferromagnet with an easy axis parallel to the current direction. We notice that the field-like torque with an appropriate sign provides an additional field, modifying the dynamic trajectory of the magnetization, and drives the auto-oscillation. The condition on the sign of the field-like torque is satisfied for a typical nonmagnet used in spin Hall devices such as tungsten.
Multi- and single-reference methods for the analysis of multi-state peroxidation of enolates
Authors: Ortega P. , Gil-Guerrero S. , Veselinova A. , Zanchet A. , González-Sánchez L. , Jambrina P. G. , Sanz-Sanz C.
Published: April 2021

In spite of being spin-forbidden, some enzymes are capable of catalyzing the incorporation of O2(Σg−3) to organic substrates without needing any cofactor. It has been established that the process followed by these enzymes starts with the deprotonation of the substrate forming an enolate. In a second stage, the peroxidation of the enolate formation occurs, a process in which the system changes its spin multiplicity from a triplet state to a singlet state. In this article, we study the addition of O2 to enolates using state-of-the-art multi-reference and single-reference methods. Our results confirm that intersystem crossing is promoted by stabilization of the singlet state along the reaction path. When multi-reference methods are used, large active spaces are required, and in this situation, semistochastic heat-bath configuration interaction emerges as a powerful method to study these multi-configurational systems and is in good agreement with PNO-LCCSD(T) when the system is well-represented by a single-configuration.
Structure and Facile Synthesis of Proton-Conducting [Fe(CN)
Authors: Ding Wei-Min , Zhao Yao , Zhang Hong-Yu , Zhang Feng-Ming
Published: April 2021

Proton-conducting materials are a key component of proton exchange membrane fuel cells (PEMFCs) and the advantage of clear structural information in crystal materials offers a pathway for the investigation of the proton-conducting mechanism and pathway. In this work, a new Cd2+ coordination polymer material (compound 1) with the formula {[Cd3(bipy)3(H2O)4][Fe(CN)6]2·2H2O·2(bipy)}n was successfully synthesized by a solution diffusion method and its proton conduction ability was further determined. Crystal structure analysis confirms the coordination of [Fe(CN)6]3–, 4,4′-bipyridine, and H2O molecules to Cd2+ in the three dimensional structure of compound 1. Also, we confirmed that compound 1 of 500–800 nm particle size could be synthesized on a large scale by a facile stirring method. Proton-conductivity analyses revealed that compound 1 shows a water-mediated proton conduction behaviour because the conductivity increased apparently with the increase of relative humidity. Further investigation shows that the highest proton-conductivity of 8.36 × 10−4 S cm−1 was observed at 60°C and 95 % relative humidity, and the mechanism analysis suggests a Vehicle mechanism exists in the proton conduction process of compound 1.
Cholinergic suppression of hippocampal sharp-wave ripples impairs working memory
Authors: Zhang Yiyao , Cao Liang , Varga Viktor , Jing Miao , Karadas Mursel , Li Yulong , Buzsáki György
Published: April 2021

Significance

Theta oscillations supported by the medial septum are believed to be a critical mechanism for learning and memory. We report that, in addition to theta oscillations, hippocampal SPW-Rs are important. Enhanced cholinergic activation in the hippocampus during the delay between choices in a spontaneous alternation task abolished SPW-Rs and impaired choice performance in mice. Our findings also demonstrate that the outcome of optogenetic manipulation of a key neurotransmitter, acetylcholine (ACh), depends on the state of the brain at the time of the perturbation.
Lonicera morrowii (Morrow's honeysuckle).
Authors: Cottrell Vicki
Published: April 2021

A datasheet on Lonicera morrowii covering, as an economically important tree, its taxonomy, importance, silviculture, distribution, biology and ecology, uses, products and pests.
Variational regularization theory based on image space approximation rates
Authors: Miller Philip
Published: April 2021

We present a new approach to convergence rate results for variational regularization. Avoiding Bregman distances and using image space approximation rates as source conditions we prove a nearly minimax theorem showing that the modulus of continuity is an upper bound on the reconstruction error up to a constant. Applied to Besov space regularization we obtain convergence rate results for 0, 2, q- and 0, p, p-penalties without restrictions on p, q ∈ (1, ∞). Finally we prove equivalence of Hölder-type variational source conditions, bounds on the defect of the Tikhonov functional, and image space approximation rates.
Optimal-order convergence of Nesterov acceleration for linear ill-posed problems*
Authors: Kindermann Stefan
Published: April 2021

We show that Nesterov acceleration is an optimal-order iterative regularization method for linear ill-posed problems provided that a parameter is chosen accordingly to the smoothness of the solution. This result is proven both for an a priori stopping rule and for the discrepancy principle under Hölder source conditions. Furthermore, some converse results and logarithmic rates are verified. The essential tool to obtain these results is a representation of the residual polynomials via Gegenbauer polynomials.
Nonconvex and nonsmooth total variation regularization method for diffuse optical tomography based on RTE
*
Authors: Tang Jinping
Published: April 2021

Diffuse optical tomography with near-infrared light is a promising technique for noninvasive study of the functional characters of human tissues. Mathematically, it is a seriously ill-posed parameter identification problem. For the purpose of better providing both segmentation and piecewise constant approximation of the underlying solution, nonconvex nonsmooth total variation based regularization functional is considered in this paper. We first give a theoretical study on the well-posedness of solutions corresponding to this minimization problem in the Banach space of piecewise constant functions. Moreover, our theoretical results show that the minimizers corresponding to a sequence nonconvex nonsmooth potential functions which converge to the 0–1 functions, can be used to approximate the solution to the weak Mumford–Shah regularization. Then from the numerical side, we propose a double graduated nonconvex Gauss–Newton algorithm to solve this nonconvex nonsmooth regularization. All illustrations and numerical experiments give a flavor of the possibilities offered by the minimizers of the proposed algorithm.
Revealing the structure of light pseudoscalar mesons at the electron–ion collider
Authors: Arrington J , Gayoso C Ayerbe , Barry P C , Berdnikov V , Binosi D , Chang L , Diefenthaler M , Ding M , Ent R , Frederico T , Furletova Y , Hobbs T J , Horn T , Huber G M , Kay S J D , Keppel C , Lin H-W , Mezrag C , Montgomery R , Pegg I L , Raya K , Reimer P , Richards D G , Roberts C D , Rodríguez-Quintero J , Romanov D , Salmè G , Sato N , Segovia J , Stepanov P , Tadepalli A S , Trotta R L
Published: April 2021

The questions of how the bulk of the Universe’s visible mass emerges and how it is manifest in the existence and properties of hadrons are profound, and probe the heart of strongly interacting matter. Paradoxically, the lightest pseudoscalar mesons appear to be key to a further understanding of the emergent mass and structure mechanisms. These mesons, namely, the pion and kaon, are the Nambu–Goldstone boson modes of quantum chromodynamics (QCD). Unravelling their partonic structure and the interplay between emergent and Higgs-boson mass mechanisms is a common goal of three interdependent approaches—continuum QCD phenomenology, lattice-regularised QCD, and the global analysis of parton distributions—linked to experimental measurements of hadron structure. Experimentally, the anticipated electron–ion collider will enable a revolution in our ability to study pion and kaon structures, accessed by scattering from the ‘meson cloud’ of the proton through the Sullivan process. With the goal of enabling a suite of measurements that can address these questions, we examine key reactions that identify the critical detector-system requirements needed to map tagged pion and kaon cross-sections over a wide range of kinematics. The excellent prospects for extracting pion structural, functional, and form-factor data are outlined, and similar prospects for kaon structures are discussed in the context of a worldwide programme. The successful completion of the programme outlined herein will deliver deep, far-reaching insights into the emergence of pions and kaons, their properties, and their role as QCD’s Goldstone boson modes.
DOI estimation through signal arrival time distribution: a theoretical description including proof of concept measurements
Authors: Loignon-Houle Francis , Gundacker Stefan , Toussaint Maxime , Camirand Lemyre Félix , Auffray Etiennette , Fontaine Réjean , Charlebois Serge A , Lecoq Paul , Lecomte Roger
Published: April 2021

The challenge to reach 10 ps coincidence time resolution (CTR) in time-of-flight positron emission tomography (TOF-PET) is triggering major efforts worldwide, but timing improvements of scintillation detectors will remain elusive without depth-of-interaction (DOI) correction in long crystals. Nonetheless, this momentum opportunely brings up the prospect of a fully time-based DOI estimation since fast timing signals intrinsically carry DOI information, even with a traditional single-ended readout. Consequently, extracting features of the detected signal time distribution could uncover the spatial origin of the interaction and in return, provide enhancement on the timing precision of detectors. We demonstrate the validity of a time-based DOI estimation concept in two steps. First, experimental measurements were carried out with current LSO:Ce:Ca crystals coupled to FBK NUV-HD SiPMs read out by fast high-frequency electronics to provide new evidence of a distinct DOI effect on CTR not observable before with slower electronics. Using this detector, a DOI discrimination using a double-threshold scheme on the analog timing signal together with the signal intensity information was also developed without any complex readout or detector modification. As a second step, we explored by simulation the anticipated performance requirements of future detectors to efficiently estimate the DOI and we proposed four estimators that exploit either more generic or more precise features of the DOI-dependent timestamp distribution. A simple estimator using the time difference between two timestamps provided enhanced CTR. Additional improvements were achieved with estimators using multiple timestamps (e.g. kernel density estimation and neural network) converging to the Cramér–Rao lower bound developed in this work for a time-based DOI estimation. This two-step study provides insights on current and future possibilities in exploiting the timing signal features for DOI estimation aiming at ultra-fast CTR while maintaining detection efficiency for TOF PET.
Energy transfer in interaction of a cold atmospheric pressure plasma jet with substrates
Authors: Hansen Luka , Goldberg Benjamin M , Feng David , Miles Richard B , Kersten Holger , Reuter Stephan
Published: April 2021

The energy flux of a nanosecond pulsed cold atmospheric pressure (CAP) plasma jet in contact with a substrate surface was measured to improve the understanding of the correlation between energy flux, flow dynamics and applied electrical power. The flow pattern properties of the CAP jet were imaged using Rayleigh scattering showing a transition from laminar to turbulent flow at Reynolds number of 700, significantly smaller than the conventional critical Reynolds number of 2040. The energy flux to the surface was determined using a passive thermal probe as a substrate dummy. As expected, the energy flux decreases with increasing distance to the nozzle. Measurements of the floating potential of the probe revealed a strong positive charging (up to 165 V) attributed to ion flux originating mainly from Penning ionization by helium metastables. Negative biasing of the probe doubled the energy flux and showed a significantly increased ion contribution up to a nozzle distance of 6 mm to the surface. For positive biasing an increased contribution of electrons and negative ions was only found at 3 mm distance. The relevance of particle transport to the surface is shown by switching from laminar to turbulent flow resulting in a decreased energy flux. Furthermore, a linear correlation of energy flux and input power was found.
Design, control, and experiments of a fluidic soft robotic eel
Authors: Chen Yihong , Wang Tao , Wu Chaofei , Wang Xiao
Published: April 2021

This work develops a fluidic soft robotic eel which combines the adaptability of soft material and the flexibility of eel-shaped body together. The soft eel-like robot consists of multiple soft actuation segments each of which is capable of bidirectional bending by two embedded symmetrical fluidic chambers. Propulsion will be produced when proper control rules are applied to the bending angles of the actuation segments. Robot design, prototype fabrication and system integration are described step by step. A motion controller based on central pattern generator (CPG) is designed for the soft eel-like robot by using identified parameters. Substantial experiments are implemented to evaluate the performance of the prototype. It is shown that the soft eel-like robot can flexibly perform linear motion and turning motion. Moreover, the soft eel-like robot keeps good continuity even when the parameters of the CPG-based controller changes. In general, the experimental results verify the effectiveness of the design and control methods for the soft eel-like robot, which provides a potential candidate to underwater exploration with limited space.
Primordial Deuterium after LUNA: concordances and error budget
Authors: Pisanti O. , Mangano G. , Miele G. , Mazzella P.
Published: April 2021

The accurate evaluation of the nuclear reaction rates and
corresponding uncertainties is an essential requisite for a precise
determination of light nuclide primordial abundances. The recent
measurement of the D(p, γ)3He radiative capture cross
section by the LUNA collaboration, with its order 3% error,
represents an important step in improving the theoretical prediction
for Deuterium produced in the early universe. In view of this recent
result, we present in this paper a full analysis of its abundance,
which includes a new critical study of the impact of the other two
main processes for Deuterium burning, namely the deuteron-deuteron
transfer reactions, D(d, p)3H and D(d, n)3He. In particular,
emphasis is given to the statistical method of analysis of
experimental data, to a quantitative study of the theoretical
uncertainties, and a comparison with similar studies presented in
the recent literature. We then discuss the impact of our study on
the concordance of the primordial nucleosynthesis stage with the
Planck experiment results on the baryon density Ωbh2 and
the effective number of neutrino parameter Meff, as function of
the assumed value of the 4He mass fraction Yp. While after the
LUNA results, the value of Deuterium is quite precisely fixed, and
points to a value of the baryon density in excellent agreement with
the Planck result, a combined analysis also including Helium leads
to two possible scenarios with different predictions for
Ωbh2 and , depending on the value adopted for Yp
from astrophysical measurements. We argue that new results on the
systematics and mean value of Yp in metallicity poor environments
would be of great importance in assessing the overall concordance of
the standard cosmological model.
Evaluation of Stellar Parameters and Calibrating the Surface Gravity log g for LAMOST-II Median Resolution Survey
Authors: Chen Xiang-Lei , Luo A-Li , Chen Jian-Jun , Du Bing , Wang Rui , Zuo Fang , Zhang Shuo , Li Yin-Bi , Lu Yan , Chen Jing , Qu Caixia
Published: April 2021

The LAMOST II survey began in the fall of 2018, and LAMOST formally released the obtained medium-resolution spectra (MRS) as well as catalogs of stellar parameters and radial velocities (RV) derived from the MRS in the seventh LAMOST data release (DR7). Compared with the RVs and parameters from high-resolution SDSS14/APOGEE spectra, nearly no RV discrepancy was found, with only dispersion around one km s−1. The T
eff of MRS was 27.79 K systematically lower than that of APOGEE, and the 1σ difference was approximately 60.40 K. For metallicity, the [Fe/H] of the MRS was 0.11 dex poorer than that of APOGEE, with a dispersion of 0.07 dex. More apparently, the offset of log g was 0.14 dex, and the scatter was 0.23 dex. The gravities of APOGEE have been corrected through seismological data. Similarly, in this study, we tried to calibrate LAMOST MRS log g with the Kepler data for red clump stars and red giant branch stars based on two fitted calibration relations. In addition, we found log g of a small fraction late-K type giants mistakenly measured as dwarfs, and vice versa, on the HR diagram generated with LAMOST T
eff and Gaia absolute magnitudes. This was because the MRS parameters were measured from blue band spectra only. The measurements of log g for late-K stars can be significantly improved by adding red spectra.
Outlier Prediction and Training Set Modification to Reduce Catastrophic Outlier Redshift Estimates in Large-scale Surveys
Authors: Wyatt M. , Singal J.
Published: April 2021

We present results of using individual galaxies’ probability distribution over redshift as a method of identifying potential catastrophic outliers in empirical photometric redshift estimation. In the course of developing this approach we develop a method of modification of the redshift distribution of training sets to improve both the baseline accuracy of high redshift (z > 1.5) estimation as well as catastrophic outlier mitigation. We demonstrate these using two real test data sets and one simulated test data set spanning a wide redshift range (0 < z < 4). Results presented here inform an example “prescription” that can be applied as a realistic photometric redshift estimation scenario for a hypothetical large-scale survey. We find that with appropriate optimization, we can identify a significant percentage (>30%) of catastrophic outlier galaxies while simultaneously incorrectly flagging only a small percentage (<7% and in many cases <3%) of non-outlier galaxies as catastrophic outliers. We find also that our training set redshift distribution modification results in a significant (>10) percentage point decrease of outlier galaxies for z > 1.5 with only a small (<3) percentage point increase of outlier galaxies for z < 1.5 compared to the unmodified training set. In addition, we find that this modification can in some cases cause a significant (∼20) percentage point decrease of galaxies which are non-outliers but which have been incorrectly identified as outliers, while in other cases cause only a small (<1) increase in this metric.
Biases from Non-simultaneous Regression with Correlated Covariates: A Case Study from Supernova Cosmology
Authors: Dixon Samantha
Published: April 2021

Several Type Ia supernova analyses make use of non-simultaneous regressions between observed supernova and host galaxy properties and supernova luminosity: first the supernova magnitudes are corrected for their light curve shape and color, and then they are separately corrected for their host galaxy masses. This two-step regression methodology does not introduce any biases when there are no correlations between the variables regressed in each correction step. However, correlations between these covariates will bias estimates of the size of the corrections, as well as estimates of the variance of the final residuals. In this work, we analyze the general case of non-simultaneous regression with correlated covariates to derive the functional forms of these biases. We also simulate this effect on data from the literature to provide corrections to remove these biases from the data sets studied. The biases examined here can be entirely avoided by using simultaneous regression techniques.
The Properties of Semi-Simple Splicing System Over Alternating Group, A3
Authors: Selvarajoo Mathuri , Heng Fong Wan , Sarmin Nor Haniza , Turaev Sherzod
Published: April 2021

Splicing system was introduced by Head in 1987 in order to explore the recombinant behaviour of deoxyribonucleic acid (DNA) strands in the presence of restriction enzymes and ligases. Restriction enzymes cut the DNA strands into a left - pattern and right-pattern while the ligases recombine the left-pattern of the first string with the right-pattern of the second string and vice-versa. Semi-simple splicing system is a variant of splicing system where the splicing of DNA strands will be at two distinct sites. Splicing languages generated from the splicing system are classified based on their computational power, according to the Chomsky Hierarchy. Previous researchers found that the splicing system of finite set of strings and rules generates only regular languages which has the lowest computational power. Hence, some restriction has been introduced to increase the computational power of splicing languages generated. In this research, an element of alternating group of order three is associated with the initial strings of semi-simple splicing system to generate non-regular languages which has higher computational power. Some lemmas and theorems are proven to show that associating the alternating group to the initial strings could increase the computational power of the splicing languages.
A Study On Virtual Intelligence
Authors: Krishna R. Sathya Bama , Praveena D. Anto , Nazhath Nafizza N , Naveena Ramesh Vardhini J
Published: April 2021

Virtual Intelligence can be otherwise known as digital intellect. VI is one of the developing technologies of this decade. It is the result of union of two technologies that are swiftly shooting up. They are Virtual Reality and Artificial Intelligence. While Artificial Intelligence will make machines react like an individual, VR will create an imaginary computer universe. This tech intends in transforming machines more like people. Using this VI technology, one can feel virtual world of their desire. This technology is utilized in many fields. Virtual Intelligence will integrate the mode of teaching. This will boost the gaming sector and will play a role in automation.
Automatic Motion Triggered Street Light Using IoT
Authors: Roobini M.S. , Suji Helen L. , Viji Amutha Mary A. , Selvan Mercy Paul , Jancy S.
Published: April 2021

Smart Street light is a computerized methodology that mechanizes the road path. The aim of Smart Street light is decreasing force utilization when are vehicles are not there. The Smart road light will gleam with high power when there are vehicles are moving and the power will stay diminish. With this progression of innovation, things become less difficult and it becomes simple for all people on the planet today. Robotization is a method of controlling human work in the creation of products.
Steady Marangoni instabilities in variable-viscosity liquid layer in the presence of insoluble surfactant
Authors: Kechil Seripah Awang , Allias Razihan
Published: April 2021

The ability to control the complex convective flow patterns is important and one of the factors that alter the dynamics of the surface tension is surface-active agents or surfactants. Surfactants affect the surface tension at the free upper surface by producing tangential stress. This study theoretically examines the onset of steady instabilities in a thin nondeformable and deformable variable-viscosity liquid layer in the presence of insoluble surfactant. The surface tension at the free surface is assumed to be linearly dependent on temperature and concentration gradients. The dynamic viscosity is assumed to be exponentially dependent on temperature. The stability problems are governed by the systems of nonlinear partial differential equations consisting of continuity, momentum and energy equations. Linear stability analysis consisting of scaling, perturbation of infinitesimal disturbances and superposition in normal modes are used to transform the system of partial differential equations into system of ordinary differential equations. The exact analytical solutions are derived and the marginal curves are illustrated to show effects of some controlling parameters particularly the variable viscosity and elasticity parameter. Viscosity variation and elasticity parameter of surfactant act as destabilizer while the Biot number and Lewis number stabilize. For deformable surface, convection sets in at long wavelength for liquid with variable viscosity but convection occurs at short wavelength for constant viscosity liquid.