bluuebunny/crossref_metadata_2025 huggingface dataset:
Landau theory-based relaxational modeling of first-order magnetic transition dynamics in magnetocaloric materials
Authors: Costa Rui M , Lovell Edmund , Almeida R , Pinto R M C , Cohen Lesley F , Pereira A M , Araújo João P , Belo J H
Published: February 2023

The magnetocaloric effect is often largest within the neighborhood of a first-order phase transition. This effect can be utilized in magnetocaloric refrigeration, which completely eliminates the need for the greenhouse gases utilized in conventional refrigeration. However, such transitions present unique dynamical effects and are accompanied by hysteresis, which can be detrimental for such refrigeration applications. In this work, a Landau theory-based relaxational model is used to study the magnetic hysteresis and dynamics of the first-order magnetic transition of LaFe13−x
Si
x
. Fitting the experimental magnetization data as a function of applied magnetic field under different field sweep rates with this model provided the Landau parameters (A, B, and C) and the kinetic coefficient of the studied material. We demonstrate the tendency of the magnetic hysteresis to increase with the magnetic field sweep rate, underlining the importance of studying and minimizing the magnetic hysteresis in magnetic refrigerants at practical field sweep rates. While evaluating the temperature dependence of the time required for a complete transition to occur, a nonmonotonic behavior and a sharp peak were found for temperatures near the transition temperature. Such peaks occur at the same temperature as the peak of the magnetic entropy change for low fields, whereas for higher fields the two peaks decouple. This information is critical for technological applications (such as refrigerators/heat pumps) as it provides guidelines for the optimization of the magnetic field amplitude in order to reduce the transition timescale and consequently maximize the machine operational frequency and amount of heat that is pumped in/out per second.
Method to subtract the effect of interference reactions that produce same product nucleus on the cross-section measurements of the target nuclear reaction and the cross-section of the 183W(n,p)183Ta reaction around 14 MeV neutrons
*
Authors: Song Yueli , Zhou Fengqun , Yuan Shuqing , Ji Pengfei , Zhang Xiaopeng , Hao Yajuan , Li Yong
Published: February 2023

For the problem of two or more nuclear reactions producing the same product nucleus in the actual cross-section measurements of nuclear reactions, a method is given for subtracting the effect of interference reactions that produce the same product nucleus on the cross-section measurements of the target nuclear reaction. The cross-section values were measured for the 183W(n,p)183Ta reaction at four different neutron energies from 13.5 to 14.8 MeV using the activation technique. In the process of calculating the cross-section data, the effects of the interference reactions 184W(n,d)183Ta and 184W(n,n+p)183Ta were subtracted using the above method. At the same time, the effect of the 186W(n,α)183Hf

→

β

−

183Ta process was also subtracted by using the previously developed method. Analysis and comparison show that our experimental cross-section values for the 183W(n,p)183Ta reaction agree with the previous results in the case of using the samples of enriched 183W at close energies. Discrepancies in the previous cross-section data of the 183W(n,p)183Ta reaction are clarified, and the recommendation excitation function curve for the 183W(n,p)183Ta reaction is given by adopting the nuclear theoretical model program system TALYS-1.95.
Quasielastic (p, n) reactions described by a microscopic optical model based on the Gogny force
Authors: Moraña Juan Lopez , Viñas Xavier
Published: February 2023

In this work, we want to study quasielastic (p, n) exchange reactions using a semi-microscopic optical model derived from a previous work, Lopez Moraña and Viñas (2021 J. Phys.
G48 035104) based on a nuclear matter approach where the real and imaginary parts are given by the first and second order terms, respectively, of the mass operator obtained by a Brueckner–Hartree–Fock calculation using a G-matrix built up with an effective Gogny interaction. The study of these quasielastic reactions is performed within a Distorted Wave Born Approximation to evaluate the wave functions in the entrance and exit channels, which in turn are used to compute the transition matrix elements. This model, which is free of adjustable parameters, provides a reasonably good agreement with the considered experimental data, namely differential cross sections, analyzing powers and total cross sections, of different reactions spanned along the periodic table at several energies.
Prediction of various defects and material flow behavior during dissimilar FSW of DH36 shipbuilding steel and marine grade AA5083 using FE-based CEL approach
Authors: Bhattacharjee Rituraj , Datta Susmita , Hammad Ahmed , Biswas Pankaj
Published: February 2023

Dissimilar friction stir welding (FSW) of steel-Al is a very tedious job. Inappropriate welding process parameters can lead to the initiation of inevitable defects associated with dissimilar FSW processes. These can be presented as tunnel defects, void generation, excessive flash formation, and other surface irregularities. Using conventional experimental trials makes it usually challenging to identify such defects. This research adopted an Abaqus/Explicit® framework utilizing a 3D thermo-mechanical based coupled Eulerian-Lagrangian (CEL) methodology. In order to predict commonly observed defects in the FSW process, the proposed FEM uses the volume of fluid approach. By monitoring the material flow into and out of the computational/void domain, the suggested framework has made it feasible to predict surface, sub-surface, and volumetric defects. Defect formation is studied at a constant tool rotation speed of 875 rpm, welding speed of 90 mm min−1, and tilt angle of 0°. Tilt angles of 0° caused welding joints with a small tunnel defect. Thermal history, axial force variation, and material flow behavior are all strongly aligned with the principle of defect generation. An experimental trial has been conducted to validate the proposed finite element model. The previous analysis found that the average axial force closely matches the welding-related experimental findings with a percentage error of 7.85%. While a proportion error of approximately ∼0.57% was found between the compared numerical and experimental diameters of the pin end-hole defect. Furthermore, the proposed model accurately predicted the process of material flow along the thickness direction of the workpiece. It was seen that the stress generated at the root of the flashes reached a higher value ranging between 485.6 and 582.7 MPa. Finally, a good agreement between the numerical results and the experimental trial was established, showing the robustness of the developed computational FEM technique.
Questioning authority through a scientific inquiry on heliocentrism
Authors: Ng Yee-Hong
Published: February 2023

In this paper, we present an outline for students to apply the iterative process of scientific inquiry to the study of a few models that describe our Universe. Ultimately, they will falsify some of the models such as the geocentric model, and appreciate why the heliocentric model is the most up-to-date and accepted description of our Universe. As far as possible, emphasis is also placed on allowing students to question authority, to explore alternate explanations, and to challenge well-established conclusions. The approach presented in this paper should help students improve in their critical thinking abilities, and in the process, train them to become the better scientists that we want them to be.
Multi-scale dilated dense reconstruction network for limited-angle computed tomography
Authors: Zhou Haichuan , Zhu Yining , Zhang Huitao , Zhao Xing , Zhang Peng
Published: February 2023

Objective. Due to the incomplete projection data, the image reconstructed by limited-angle computed tomography (CT) usually suffers from significant artifacts, by which the structural details are heavily blurred. In this study, we aim to develop a novel approach to improve the limited-angle CT reconstruction performance, especially for the narrow scanning angular range. Approach. A deep learning based iterative framework for limited-angle tomography is proposed, which is named multi-scale dilated dense reconstruction network (MSDDRNet). The MSDDRNet utilizes a multi-scale dilated dense convolution neural network (MSDD-CNN) with conventional reconstruction algorithm for predicting image from incomplete projection data. The MSDD-CNN enhances the image features in the network by merging the DenseNet-Like structure, which serves to restore invisible singularities and reduce artifacts, as well as introducing constraints on the projection domain data into the iterative process to achieve better image detail recovery. Additionally, to improve the training speed of the network, we use a strategy of pre-training and model migration. Main results. Numerical experiments demonstrate that the proposed MSDDRNet performs well in terms of artifact correction, noise reduction and structure recovery compared to existing methods with limited scan angles, and we also extend the proposed method to more general scanning condition and other application such as dental CT data. Significance. The proposed method is a general framework, which can be applied to other CT problems, such as low dose CT, sparse-data CT and spectral CT.
Quantitative photoacoustic tomography with light fluence compensation based on radiance Monte Carlo model
Authors: Zheng Sun , Yingsa Hou , Meichen Sun , Qi Meng
Published: February 2023

Objective. Photoacoustic tomography (PAT) is a rapidly evolving imaging modality that provides images with high contrast and spatial resolution showing the optical properties of biological tissues. The photoacoustic pressure is proportional to the product of the optical absorption coefficient and the local light fluence. The essential challenge in reconstructing quantitative images representing spatially varying absorption coefficients is the unknown light fluence. In addition, optical attenuation induces spatial variations in the light fluence, and the heterogeneity of the fluence determines the limits of reconstruction quality and depth. Approach. In this work, a reconstruction enhancement scheme is proposed to compensate for the variation in the light fluence in the absorption coefficient recovery. The inverse problem of the radiance Monte Carlo model describing light transport through the tissue is solved by using an alternating optimization strategy. In the iteration, the absorption coefficients and photon weights are alternately updated. Main results. The method provides highly accurate quantitative images of absorption coefficients in simulations, phantoms, and in vivo studies. The results show that the method has great potential for improving the accuracy of absorption coefficient recovery compared to conventional reconstruction methods that ignore light fluence variations. Comparison with state-of-the-art fluence compensation methods shows significant improvements in root mean square error, normalized mean square absolute distance, and structural similarity metrics. Significance. This method achieves high precision quantitative imaging by compensating for nonuniform light fluence without increasing the complexity and operation of the imaging system.
Coupled simulations with SOLPS-ITER and B2.5-Eunomia for detachment experiments in Magnum-PSI
Authors: Gonzalez J , Chandra R , de Blank H J , Westerhof E
Published: February 2023

Heat loads of 10 MW m−2 are expected for steady state operation at ITER and up to 20 MW m−2 in slow transient situations. Plasma linear devices like Magnum-PSI can recreate situations close as those expected to be achieved at ITER divertor, providing easier access for diagnostics than in a tokamak. Numerical models are still necessary to complement experiments and to extrapolate relevant information to fusion devices, as the relevant atomic and molecular processes. SOLPS-ITER (formerly known as B2.5-Eirene) is typically employed to solve the plasma and neutral distribution in a coupled way for tokamak devices. For Magnum-PSI, B2.5 has been coupled with a different neutral module, named Eunomia, developed mostly for linear devices. Nevertheless, there is an interest in using SOLPS-ITER for simulating Magnum-PSI, as it would ease the process of relating linear device results with tokamaks. A previous work found significant differences in the implementation of relevant plasma-neutral processes in Eirene and Eunomia. A wide range of plasma scenarios are compared between B2.5-Eunomia and SOLPS-ITER. Although both codes produce results close to experimental Thomson scattering density and temperature near the target once the electric potential at the source is adjusted, these are achieved with completely different plasma and neutral distributions. Anomalous transport coefficients, which are other of the free-parameters in Magnum-PSI simulation, are set equal between the two codes. When studied in a wide range of neutral pressures, SOLPS-ITER shows a trend closer to experiments, as well as providing a converged solution at neutral pressures higher than 4 Pa for which B2.5-Eunomia was unable to provide a converged solution. Additional measurements of the neutral distribution in the target chamber as well as the electric potential at the source are required to determine which code is producing results closer to the experiment.
Global linear stability analysis of kinetic trapped ion mode (TIM) in tokamak plasma using the spectral method
Authors: Mandal D , Lesur M , Gravier E , Sama J N , Guillevic A , Sarazin Y , Garbet X
Published: February 2023

Trapped ion modes (TIMs) belong to the family of ion temperature gradient (ITG) modes, which are one of the important ingredients in heat turbulent transport at the ion scale in tokamak plasmas. A global linear analysis of a reduced gyro-bounce kinetic model for trapped particle modes is performed, and a spectral method is proposed to solve the dispersion relation. Importantly, the radial profile of the particle drift velocity is taken into account in the linear analysis by considering the magnetic flux ψ dependency of the equilibrium Hamiltonian

H

e
q

(
ψ
)

in both the quasi-neutrality equation and equilibrium gyro-bounce averaged distribution function

F

e
q

. Using this spectral method, linear growth rates of TIM instability in the presence of different temperature profiles and precession frequencies of trapped ions, with an approximated constant Hamiltonian and the exact ψ dependent equilibrium Hamiltonian, are investigated. The growth rate depends on the logarithmic gradient of temperature κ

T
, density κ

n
and equilibrium Hamiltonian

κ

Λ

. With the exact ψ dependent Hamiltonian, the growth rates and potential profiles are modified significantly, compared to the cases with an approximated constant Hamiltonian. All the results from the global linear analysis agree with a semi-Lagrangian based linear Vlasov solver with good accuracy. This spectral method is very fast and requires much less computation resources compared to a linear version of the Vlasov-solver based on a semi-Lagrangian scheme.
Structural design and experimental study of multi-ring and multi-disc magnetorheological valve
Authors: Yang Xiaolong , Cao Zhiqiang , Liu Gang , Xie Guojin
Published: February 2023

In order to solve the problems of small pressure drop range and achieve lower response time and small power consumption of traditional control valves in automotive hydraulic lift, the magnetic circuit method was employed to design a new multi-ring and multi-disc magnetorheological valve based on magnetorheological fluid and its pressure drop mathematical model was established. Through the electromagnetic field simulation, the effect of current size, radial damping gap size, axial damping gap size and magnetic isolation thickness affect the performance of the multi-ring and multi-disc magnetorheological valve is studied. The pressure drop characteristics and response time of the multi-ring and multi-disc MR valve under different currents, different direction of loading current and different loads have been studied experimentally. The results show that the saturation pressure drop of the multi-ring and multi-disc MR valve is greater than 7 MPa, and the response time is 136 ms–178 ms, which proves the performance advantage of the multi-ring and multi-disc MR valve.
Astrophysical observations of a dark matter-Baryon fifth force
Authors: Gresham Moira I. , Lee Vincent S.H. , Zurek Kathryn M.
Published: February 2023

We consider the effects of an attractive, long-range Yukawa interaction between baryons and dark matter (DM), focusing in particular on temperature and pulsar timing observations of neutron stars (NSs). We show that such a fifth force, with strength modestly stronger than gravity at ranges greater than tens of kilometers (corresponding to mediator masses less than 10-11eV), can dramatically enhance dark matter kinetic heating, capture, and pulsar timing Doppler shifts relative to gravity plus short range interactions alone. Using the coldest observed NS and pulsar timing array (PTA) data, we derive limits on fifth force strength over a DM mass range spanning light dark matter up to order solar mass composite DM objects. We also consider an indirect limit by combining bullet cluster limits on the DM self-interaction with weak equivalence principle test limits on baryonic self-interactions. We find the combined indirect limits are moderately stronger than kinetic heating and PTA limits, except when considering a DM subcomponent.
Laser cladding of IN713 LC superalloy with Amdry 997 powder: microstructural evolution
Authors: Khorram Ali
Published: February 2023

In this research, Amdry 997 powder was applied by a laser cladding process to the IN713 Low Carbon (IN713 LC) nickel-based superalloy. To evaluate the microstructural behaviors of the clad zones, different variables (the laser speed, laser frequency, and pulse width) were used in the laser cladding process. The final aim of this study was to achieve a clad zone without obvious cracks and pores with a low dilution ratio. The results showed that the upper region of the cladding includes very small equiaxed dendrites. The middle region of the cladding includes columnar dendrites. Equiaxed and columnar grains can be formed at the interface region. With an increase in the heat input of the laser (increasing the pulse width and laser frequency or decreasing the laser speed), the solidification rate reduces and consequently, a longer solidification time exists. Hence, more elongated grains are formed at the interface region. The microstructure of coatings in the upper and middle regions includes γ-Ni, β-NiAl and γ′-Ni3Al phases and TaC carbide, whereas the microstructure of the coatings at the interface region includes γ and β-NiAl and γ′-Ni3Al phases and M (Mo, Ta)C carbide. The optimum laser parameters that result in a low dilution ratio (14%) and a dense clad zone without obvious crack and porosity are a laser speed of 140 mm min−1,laser frequency of 14 Hz, and pulse width of 9 ms.
Prediction of LiCrTe2 monolayer as a half-metallic ferromagnet with a high Curie temperature
Authors: Xiao Li-Man , Yang Huan-Cheng , Lu Zhong-Yi
Published: February 2023

By using first-principles electronic structure calculations, we predict a new two-dimensional half-metallic ferromagnet (2DHMF) with distorted square structure, i.e., the LiCrTe2 monolayer. The results show that the LiCrTe2 monolayer is dynamically, thermally, and mechanically stable, and takes a large in-plane magnetic anisotropy, a wide spin gap, a large magnetization, and a very high Curie temperature. Under a biaxial strain ranging from –5% to +5%, the ferromagnetism, half-metallicity, and high Curie temperature are maintained well. Both tensile and compressive strains can significantly increase the magnitude of the magnetocrystalline anisotropy energy (MAE) and a transition from in-plane easy-x(y)-axis to out-of-plane easy-z-axis occurs when the compressive strain exceeds 1%. Our systematic study of the LiCrTe2 monolayer enables its promising applications in spintronics.
Structural phase transition and transport properties in topological material candidate NaZn4As3
Authors: Dong Qing-Xin , Ruan Bin-Bin , Huang Yi-Fei , Wang Yi-Yan , Zhang Li-Bo , Bai Jian-Li , Liu Qiao-Yu , Cheng Jing-Wen , Ren Zhi-An , Chen Gen-Fu
Published: February 2023

We report a comprehensive study on a layered-structure compound of NaZn4As3, which has been predicted to be an ideal topological semimetal (TSM) candidate. It is found that NaZn4As3 undergoes a structural transformation from high temperature rhombohedral to a low temperature monoclinic phase. The electric resistivity exhibits a metal-to-insulator-like transition at around 100 K, and then develops a plateau at low temperature, which might be related to the protected topologically conducting surface states. Our first-principles calculation confirms further that NaZn4As3 is a topological insulator (TI) for both different phases rather than a previously proposed TSM. The Hall resistivity reveals that the hole carriers dominate the transport properties for the whole temperature range investigated. Furthermore, an obvious kink possibly associated to the structure transition has been detected in thermopower around ∼170 K. The large thermopower and moderate κ indicate that NaZn4As3 and /or its derivatives can provide a good platform for optimizing and studying the thermoelectric performance.
Fragmentation dynamics of electron-impact double ionization of helium
Authors: Liu Shiwei , Ye Difa , Liu Jie
Published: February 2023

We study the double ionization dynamics of a helium atom impacted by electrons with full-dimensional classical trajectory Monte Carlo simulation. The excess energy is chosen to cover a wide range of values from 5 eV to 1 keV for comparative study. At the lowest excess energy, i.e., close to the double-ionization threshold, it is found that the projectile momentum is totally transferred to the recoil-ion while the residual energy is randomly partitioned among the three outgoing electrons, which are then most probably emitted with an equilateral triangle configuration. Our results agree well with experiments as compared with early quantum-mechanical calculation as well as classical simulation based on a two-dimensional Bohr’s model. Furthermore, by mapping the final momentum vectors event by event into a Dalitz plot, we unambiguously demonstrate that the ergodicity has been reached and thus confirm a long-term scenario conceived by Wannier. The time scale for such few-body thermalization, from the initial nonequilibrium state to the final microcanonical distribution, is only about 100 attoseconds. Finally, we predict that, with the increase of the excess energy, the dominant emission configuration undergoes a transition from equilateral triangle to T-shape and finally to a co-linear mode. The associated signatures of such configuration transition in the electron-ion joint momentum spectrum and triple-electron angular distribution are also demonstrated.
Filtering time-dependent covariance matrices using time-independent eigenvalues
Authors: Bongiorno C , Challet D , Loeper G
Published: February 2023

We propose a data-driven, model-free, way to reduce the noise of covariance matrices of time-varying systems. If the true covariance matrix is time-invariant, non-linear shrinkage of the eigenvalues is known to yield the optimal estimator for large matrices. Such a method outputs eigenvalues that are highly dependent on the inputs, as common sense suggests. When the covariance matrix is time-dependent, we show that it is generally better to use the set of eigenvalues that encode the average influence of the future on present eigenvalues resulting in a set of time-independent average eigenvalues. This situation is widespread in nature, one example being financial markets, where non-linear shrinkage remains the gold-standard filtering method. Our approach outperforms non-linear shrinkage both for the Frobenius norm distance, which is the typical loss function used for covariance filtering and for financial portfolio variance minimization, which makes our method generically relevant to many problems of multivariate inference. Further analysis of financial data suggests that the expected overlap between past eigenvectors and future ones is systematically overestimated by methods designed for constant covariances matrices. Our method takes a simple empirical average of the eigenvector overlap matrix, which is enough to outperform non-linear shrinkage.
Single-event effects calibration using two-photon absorption and a CMOS image sensor
Authors: Blommaert D. , Leroux P. , Caestecker A. , Meynants G.
Published: February 2023

This paper proposes a method to get an indication of the amount of electron-hole pairs that are necessary to trigger a single-event effect (SEE) in electronics by using two-photon absorption (TPA) and a CMOS image sensor. One of the most important materials in electronics is silicon, which is also the photosensitive part of CMOS image sensors. TPA can occur in it when two photons with an energy lower than the bandgap energy interact with the same electron within a short time window. This can be done by focusing a pulsed laser beam on a sensitive node in the electronics, generating a cloud of electron-hole pairs and thus simulating a SEE. We propose to first measure the necessary laser energy to generate a SEE with TPA in the electronics, to then focus the laser beam with the same laser energy in the CMOS image sensor. With the CMOS image sensor, we will be able to tell how many electrons were detected, which gives a good indication of how many electron-hole pairs were needed for the SEE. This paper first describes TPA, then characterises different CMOS image sensors to finally compare those results with heavy-ions.
Recent results from DEAP-3600
Authors: Lai M.
Published: February 2023

DEAP-3600 is the largest running dark matter detector filled with liquid argon, set at SNOLAB, in Sudbury, Canada, 2 km underground. The experiment holds the most stringent exclusion limit in argon for WIMPs above 20 GeV/c2. In the most recent published analysis, the background events due to α-induced scintillation in the neck of the detector limited the sensitivity. The sensitivity of the detector in the next WIMP search will be improved thanks to the decrease in backgrounds achieved by hardware upgrades and applying multivariate analyses. Moreover, the WIMP analysis has been revisited in terms of a non-relativistic effective field theory framework, and the impact of possible substructures in the galactic dark matter halo was explored. This analysis was motivated by the latest results from Gaia and the Sloan Sky Digital Survey. Here DEAP-3600 set the world’s best exclusion limit for xenon-phobic dark matter scenarios. Finally, a custom-developed analysis has recently pointed out the extraordinary sensitivity to ultra-heavy, multi-scattering dark matter candidates, resulting in world-leading exclusion limits on two composite dark matter candidates up to Planck scale masses. These proceedings, after a quick overview of the dark matter detection in DEAP-3600, outline the detector upgrades and the dark matter search results from the collaboration of the last three years.
The Bergen proton CT system
Authors: Aehle M. , Alme J. , Barnaföldi G.G. , Bodova T. , Borshchov V. , van den Brink A. , Chaar M. , Eikeland V. , Feofilov G. , Garth C. , Gauger N.R. , Genov G. , Grøttvik O. , Helstrup H. , Igolkin S. , Keidel R. , Kobdaj C. , Kortus T. , Leonhardt V. , Mehendale S. , Mulawade R.N. , Odland O.H. , O’Neill G. , Papp G. , Peitzmann T. , Pettersen H.E.S. , Piersimoni P. , Protsenko M. , Rauch M. , Ur Rehman A. , Richter M. , Röhrich D. , Santana J. , Schilling A. , Seco J. , Songmoolnak A. , Sølie J.R. , Tambave G. , Tymchuk I. , Ullaland K. , Varga-Köfaragó M. , Volz L. , Wagner B. , Wendzel S. , Wiebel A. , Xiao R. , Yang S. , Yokoyama H. , Zillien S.
Published: February 2023

The Bergen proton Computed Tomography (pCT) is a prototype detector under construction. It aims to have the capability to track and measure ions’ energy deposition to minimize uncertainty in proton treatment planning. It is a high granularity digital tracking calorimeter, where the first two layers will act as tracking layers to obtain positional information of the incoming particle. The remainder of the detector will act as a calorimeter. Beam tests have been performed with multiple beams. These tests have shown that the ALPIDE chip sensor can measure the deposited energy, making it possible for the sensors to distinguish between the tracks in the Digital Tracking Calorimeter (DTC).
Effect of valve spacing on peristaltic pumping
Authors: Wolf Ki Tae , Poorghani Amir , Dixon J Brandon , Alexeev Alexander
Published: February 2023

Peristaltic fluid pumping due to a periodically propagating contraction wave in a vessel fitted with one-way elastic valves is investigated numerically. It is concluded that the valve spacing within the vessel relative to the contraction wavelength plays a critical role in providing efficient pumping. When the valve spacing does not match the wavelength, the valves open asynchronously and the volume of the vessel segments bounded by two consecutive valves changes periodically, thereby inducing volumetric fluid pumping. The volumetric pumping leads to higher pumping flowrate and efficiency against an adverse pressure gradient. The optimum pumping occurs when the ratio of valve spacing to contraction wavelength is about

2

/

3

. This pumping regime is characterized by a longer period during which the valves are open. The results are useful for further understanding the pumping features of lymphatic system and provide insight into the design of biomimetic pumping devices.
Contact geometric approach to Glauber dynamics near a cusp and its limitation
Authors: Goto Shin-itiro , Lerer Shai , Polterovich Leonid
Published: February 2023

We study a nonequilibrium mean field Ising model in the low temperature phase regime, where metastable equilibrium states develop a cuspidal (spinodal) singularity. We focus on celebrated Glauber dynamics, and design a contact Hamiltonian flow which captures some of its rough features in this regime. We prove, however, that there is an inevitable discrepancy between the scaling laws for the relaxation time in the Glauber and the contact Hamiltonian dynamical systems.
ZnO nanoparticles-modified polycaprolactone-gelatin membranes for guided/bone tissue regeneration, antibacterial and osteogenic differentiation properties
Authors: Prado-Prone Gina , Silva-Bermudez Phaedra , Rodil Sandra E , Ganjkhani Yasaman , Moradi Ali-Reza , Méndez Franklin J , García-Macedo Jorge A , Bazzar Masoomeh , Almaguer-Flores Argelia
Published: February 2023

Periodontitis is a highly prevalent infectious disease that causes the progressive destruction of the periodontal supporting tissues. If left untreated, it can lead to tooth loss impairing oral function, aesthetics, and the patient’s overall quality of life. Guided and Bone Tissue Regeneration (GTR/BTR) are surgical therapies based on the placement of a membrane that prevents epithelial growth into the defect, allowing the periodontal/bone cells (including stem cells) to regenerate or restore the affected tissues. The success of these therapies is commonly affected by the local bacterial colonization of the membrane area and its fast biodegradation, causing postoperative infections and a premature rupture of the membrane limiting the regeneration process. This study presents the antibacterial and osteogenic differentiation properties of polycaprolactone-gelatin (PCL-G) electrospun membranes modified with ZnO nanoparticles (ZnO-NPs). The membranes´ chemical composition, surface roughness, biodegradation, water wettability, and mechanical properties under simulated physiological conditions, were analyzed by the close relationship with their biological properties. The PCL-G membranes modified with 1, 3, and 6% w/w of ZnO-NPs showed a significant reduction in the planktonic and biofilm formation of four clinically relevant bacteria;A. actinomycetemcomitansserotype b, P. gingivalis,E. coli, andS. epidermidis. Additionally, the membranes presented appropriate mechanical properties and biodegradation rates to be potentially used in clinical treatments. Notably, the membranes modified with the lowest concentration of ZnO-NPs (1% w/w) stimulated the production of osteoblast markers and calcium deposits in human bone marrow-derived mesenchymal stem cells (BM-MSC) and were biocompatible to human osteoblasts cells (hFOB). These results suggest that the PCL-G membranes with 1% w/w of ZnO-NPs are high-potential candidates for GTR/BTR treatments, as they were the most effective in terms of better antibacterial effectiveness at a lower NPs-concentration while creating a favorable cellular microenvironment for bone growth.
Organizing in the “American Congo”: Mississippi’s Freedom Summer and its aftermath
Authors: Holt Thomas C.
Published: February 2023

Following the “March on Washington for Jobs and Freedom” in 1963, the civil rights movement targeted small towns and rural areas of the Deep South, where it discovered that conditions required different tactics than the sit-ins and street marches deployed in New South cities that eventually resulted in the passage of the Civil Rights Act of 1964. For the large black population still residing in the rural Deep South, however, a focus on gaining voting rights was more directly relevant to improving black livelihoods and safety than challenges to discrimination in public accommodations. The power of the ballot in the hands of the black majorities still resident in many plantation counties was a direct threat to continued white political control, however. White populations responded with deadly violence, precipitating a crisis that eventually led to passage of the Voting rights Act of 1965.
African American History: A Very Short Introduction
Authors: Holloway Jonathan Scott
Published: February 2023

What does it mean to be an American? The story of the African American past demonstrates the difficulty in answering this seemingly simple question. If being “American” means living in a land of freedom and opportunity, what are we to make of those Americans who were enslaved and who have suffered from the limitations of second-class citizenship; throughout their lives? African American history illuminates the United States’ core paradoxes, inviting profound questions about what it means to be an American, a citizen, and a human being.This book considers how, for centuries, African Americans have fought for what the black feminist intellectual Anna Julia Cooper called “the cause of freedom.”
Resistance and African American identity before the Civil War
Authors: Holloway Jonathan Scott
Published: February 2023

This chapter canvasses the many different ways that African Americans fought to preserve their humanity in the face of the everyday practices that were part of the slavery regime. Frederick Douglass’s famous acts of resistance and then his career as an abolitionist frame much of the chapter’s narrative. Douglass was not the only architect of resistance, however. Denmark Vesey, David Walker, Nat Turner, Harriet Tubman, Sojourner Truth, and others marked different ways to fight white supremacy, organized escape and organized violence chief among them. Of particular concern was the Fugitive Slave Law that made it clear that African Americans could never be confident that their freedom would be respected.
War, freedom, and a nation reconsidered
Authors: Holloway Jonathan Scott
Published: February 2023

This chapter explores the tensions that undergird the South’s secession from the Union and then the outbreak of the Civil War. Abraham Lincoln is often referred to as “the Great Emancipator,” but his journey toward the Emancipation Proclamation was not straight. Political pragmatism, military manpower shortages, as well as philosophical wrestling with what freedom would mean for African Americans all affected Lincoln’s decision to move toward emancipation. Upon the war’s conclusion important issues had to be resolved regarding African American labor, education, and citizenship rights. Reconstruction marked a marked a high-water mark for post-emancipation black rights, some of which were not seen again until the emergence of the modern civil rights movement.
Epilogue
Authors: Holloway Jonathan Scott
Published: February 2023

The epilogue echoes the opening refrains of the book’s introduction: that the history of the United States is rife with paradoxes and often shattering juxtapositions when viewed through the lens of the black experience. Despite decades of civil rights gains and social progress, Black Lives Matter—a grassroots effort to call attention to civil rights denied—emerged. The openings of the National Memorial for Peace and Justice in Alabama and the Smithsonian’s National Museum of African American History and Culture were powerful reminders that at least some in the country were ready to reckon with the complexity of the American past, if only to secure a freer future.
The next step: an institutional peace
Authors: Richmond Oliver P.
Published: February 2023

This chapter expounds on the notion of institutional peace and its correlation to the development of the international peace architecture (IPA). Institutional peace aims to anchor states within a specific set of values and a shared legal context through which they agree multilaterally how to behave. They also agree to police and enforce that behaviour on the part of ‘renegade’ states. Thus, the role of international institutions and law in supporting the consolidation of constitutional peace represented the next step towards building positive peace. The institutional peace framework achieved most of its sophisticated tools following the world wars, guided by the principle that territorial adjustments should benefit the concerned populations.
Peacekeeping, peacebuilding, and statebuilding
Authors: Richmond Oliver P.
Published: February 2023

This chapter examines the different approaches that emerged as liberal peace coalesced around the modern international peace architecture (IPA) development. A first-generation approach from the 1950s onwards—consisting of peacekeeping, diplomacy, and mediation—aimed at a negative peace, in which neutral military intervention brought about ceasefire often through the UN. From the late 1960s, a second-generation approach—consisting of civil society efforts—focused more on law, rights, social reconciliation, and a positive peace. By the 1990s, a third generation of approaches focused on building liberal peace through bringing together development, peacekeeping, peacebuilding, and statebuilding. A developing fourth-generation approach promises hybrid forms of peace.
Improvised suburbs
Authors: Abbott Carl
Published: February 2023

This chapter explores what happens when neither private markets nor governments can provide housing for rapidly growing urban populations. In such cases, new residents will build their own housing on cheap peripheral land, creating rings of do-it-yourself suburbs. Such settlements are often irregular, meaning the household lacks legal title to the land (“squatters”) or has ignored zooming and building codes. Improvised suburbs were a response to fast urbanization in Mediterranean countries after 1945, Latin American and Asia after roughly 1960, and Africa even more recently. These communities have gone by many names, such as barriada in Peru, favela in Brazil, and gecekondu (“built overnight”) in Turkey. The term shantytown fails to recognize the complex social networks and systems that often develop. Governments have tried to regularize such suburban settlements by extending services and recognizing land titles.
What’s wrong with suburbs
Authors: Abbott Carl
Published: February 2023

This chapter explores critical responses to suburbs in print and moving-image media. From London in the early twentieth century to Los Angeles at century’s end, suburbs have been the target of strong criticism both from intellectuals and in popular culture. The chapter first examines the social critique that suburbs are boring places that stultify individuals, break traditional social ties, and isolate women. A second environmental criticism focuses on the consumption of open space and farmland and disruption of natural ecological systems resulting from suburban expansion. Political criticism points to the inefficiency of low-density settlements and the problems of coordinating services among local governments, despite efforts to create metropolitan governance institutions. Science fiction frequently presents a dystopian vision of the suburban future. Social research points out the flaws in these arguments and finds many positive aspects to suburban life, although it is difficult to separate real problems from pervasive suburban myth.
83 ‘WHAT DOES “ACTIVE AGEING” MEAN TO YOU?’ A FIVE-COUNTRY SURVEY OF ACADEMICS, STUDENTS, ADVOCACY GROUPS, AND ‘EXPERT’ OLDER PEOPLE
Authors: Wiggin D , Velonaki V-S , Sourtzi P , Timmons S ,   EMMA Consortium
Published: February 2023

Background

Older people are projected to make up almost one third of the European population by 2060. Healthy and active ageing (HAA) is a key to maximising the opportunities that the increasingly older demographic presents. A multinational survey was conducted to inform a new online EU-based master’s programme in active ageing, and a fundamental initial issue to explore was stakeholders’ understanding of the concept of ‘active ageing’.

Methods

An anonymous online survey, in five partner countries (Ireland, Greece, Austria, Slovenia and Greece) asked senior undergraduates and recent graduates; future employers; relevant academics; and other key stakeholders (e.g. advocacy groups, policy makers, and ‘expert’ older people): ‘What does the term active ageing mean to you?’. Content analysis of their replies ensued.

Results

Within the first 473 responses, the most common concept (at nearly 50%) was active participation in society, including social engagement and other gainful activities, while hobbies and activities were also mentioned. The other main concept was that active ageing means favourable personal life qualities. This encompassed a broad range of aspects such as dignity, and physical, psychological, and social wellness. Health (physical and psychological), living longer in good health, and health promotion were often specified, while positive self-esteem, self-image, and self-respect were mentioned occasionally. Independence, including autonomy, ability to self-care, and decision-making and financial independence, was another key concept. Service provision in health and social care, and policy and rights were frequently mentioned. Most concepts were similarly reported in all five countries, but there were some nuances, such as Irish participants citing autonomy and service provision less often.

Conclusion

This European data highlights the understanding, among a range of stakeholders, of the concept of ‘active ageing’, as occurring at both a societal/service level, and at a personal level, with health, wellness and independence being key elements of the latter.
125 WARD-BASED MEDICAL TEAMS: IMPACT ON THE CARE OF THE OLDER PERSON WARD
Authors: Whelan A , Doyle P , Ryan C , Kaur I , Mulroy M
Published: February 2023

Background

The COVID-19 pandemic forced healthcare management to make structural adaptations in the interest of infection control. One such adaptation is the introduction of ward-based medical teams. The multidisciplinary team (MDT) is one of the cornerstones of geriatric medicine. Therefore, we aimed to explore the perception of the care of the older person MDT on the introduction of ward-based medical teams.

Methods

Qualitative data was collected on a geriatric ward in October 2020 via written questionnaire. The questionnaire analysed how the transition to ward based medical teams was perceived in terms of inter-professional collaboration and clinical service delivered to patients.

Results

There were 14 respondents, 10 of whom were nursing staff (71%). 86% strongly agreed that the medical team was more accessible, with most interactions occurring face-to-face. Patient care and safety was thought to have improved, 79% and 71% of respondents respectively. 93% felt they had a better rapport with the medical team. 71% felt the MDT meeting is more effective, 57% believed the meeting had greater impact on patient care.

However, 93% felt there was less workspace. 21% believed there were more daily admissions and 57% felt the majority of patient transfers from other wards were inappropriate.

Overall 86% favoured ward-based medical teams, with 57% of staff reporting that the change led to increased personal job satisfaction.

Conclusion

By increasing the geographic proximity of doctors to other professionals, doctors were more accessible, issues were tackled quicker, and there was less time wasted bleeping medical teams. Overall staff favoured a ward-based system. However, there are challenges implementing this system. Particular attention should be paid to the availability of adequate workspace, including telephones and computers. Ward transfers should be minimized as continuity of care can be compromised. Strategies should be implemented so medical charts are available to the MDT during consultant-led ward rounds.
215 WHAT IMPACT CAN ‘EMERGENCY DEPARTMENT IN THE HOME’ (EDITH) HAVE ON THE OLDER ADULT POPULATION PRESENTING WITH FALLS?
Authors: Delaney A , Doyle C , Sweeney A , Davis A , McNally S , McNamara R , Mooney R
Published: February 2023

Background

EDITH is a frailty response service providing medical and occupational therapy input to older adults living within the catchment area of a level 4 acute hospital. EDITH aims to reduce avoidable Emergency Department (ED) attendances and utilise alternative care pathways. Falls are common among older people and are often associated with poorer outcomes. Traditionally, older patients who have had a fall and contact emergency services for assistance are transferred to the ED and this can be associated with elevated risks. Additionally, older patients who have had a fall and are discharged on scene by the emergency services are at greater risk of recurring falls in the absence of immediate onward referral to community falls prevention services (Nowak and Hubbard 2009).

Methods

Paper count method data collection was completed. Inclusion criteria included referrals from the National Ambulance Service within the last 6 months.

Results

75 patients met the inclusion criteria; 34 males, 41 females with an average age of 82. 11 patients were conveyed to hospital, giving a conveyance rate of 14.6%, the average conveyance rate for the EDITH service is 7.2%. 3 patients were conveyed to ED, while 8 patients were conveyed to the Medical Assessment Unit (MAU) in the local level 3 hospital. This resulted in 72% of patients that required hospital conveyance being streamed to the MAU; traditionally 100% of these patients would have presented to ED. Overall, 85.4% of patients seen remained at home.

Conclusion

EDITH are providing targeted medical and occupational therapy assessment(s) for older adults in their homes with successful outcomes. Implementation of alternative care pathways, reduction in avoidable ED attendances and prolonged independence in the home for this patient profile are some of the favourable findings.

Reference

1. Nowak A, Hubbard RE. (2009) Falls and frailty: lessons from complex systems. Journal of the Royal Society of Medicine. 102(3):98–102.