bluuebunny/crossref_metadata_2025 huggingface dataset:
Einschätzungen zum elektronischen Rezept – eine
Querschnittstudie unter Apothekern in Deutschland
Authors: Strumann Christoph , Möller Birger , Steinhäuser Jost
Published: June 2021

Hintergrund Mit dem Modellprojekt GERDA („Geschützter
e-Rezept-Dienst der Apotheken“) wurde von der Landesapothekerkammer
(LAK) und dem Landesapothekerverband (LAV) in Baden-Württemberg die
Möglichkeit geschaffen, Rezepte im Rahmen von Online-Sprechstunden
über das von der Kassenärztlichen Vereinigung
Baden-Württemberg betriebene telemedizinische Portal
„docdirekt“, zu verordnen. Vor diesem Hintergrund war das Ziel
der Studie, Barrieren und fördernde Faktoren aufseiten der Apotheken
für die Beteiligung an einer Versorgung, die eine elektronische
Verordnung von Rezepten beinhaltet, zu explorieren und zu priorisieren. Auf
Basis dieser Determinanten wurden Empfehlungen zur Optimierung einer
erfolgreichen Implementierung ähnlicher Versorgungsangebote
abgeleitet.

Methode Es wurde ein Mixed-Methods-Design gewählt, um die
Determinanten zu explorieren und zu priorisieren. Im ersten Schritt wurden
Determinanten für die Beteiligung an einem System, welches die
elektronische Verordnung von Rezepten ermöglicht mithilfe von
Einzelinterviews mit an docdirekt beteiligten Teleärzten,
niedergelassenen Hausärzten und Apothekern exploriert.
Anschließend wurden diese Determinanten in einem zweiten Schritt durch
eine quantitative Befragung von Apothekern priorisiert.

Ergebnisse Von den 523 an der Umfrage teilgenommenen Apothekern war mehr
als die Hälfte bereit sich an einem E-Rezept-System zu beteiligen,
8,5% schließen eine zukünftige Beteiligung aus.
Insgesamt konnten 18 Determinanten für die Beteiligung an einem System,
welches die elektronische Verordnung von Rezepten ermöglicht, exploriert
werden. Der Schutz der freien Apothekenwahl wurde als wichtigster Aspekt
für eine Beteiligung identifiziert. Gefolgt von der Möglichkeit
einer Korrekturfunktion bei E-Rezepten (um z. B. Retaxierungen oder
Medikationsfehlern zu vermeiden), der Integration des E-Rezepts in die
bestehende Apotheken-EDV sowie dem gesetzlichen Ausschluss von direkten
Verträgen mit Versandapotheken. Zeitersparnisse und eine ggf.
höhere Vergütung wurden dagegen als weniger relevant
bewertet.

Schlussfolgerung Insgesamt gab über die Hälfte der
befragten Apotheken an, sich an einem E-Rezept-System beteiligen zu wollen.
Für die ab Januar 2022 geplante flächendeckende
Einführung von E-Rezepte kann der Einbezug der identifizierten
fördernden Faktoren vonseiten der Politik, Softwareentwickler und
Verbände eine wichtige Rolle bei der Implementierung spielen.
Recent Advances in Dimeric Cycloparaphenylenes as Nanotube Fragments
Authors: Sun Zhe , Li Ke
Published: June 2021

Since the discovery of cycloparaphenylenes in 2008, the chemical synthesis of more-complicated molecular systems with curved π-surfaces has been vigorously sought, giving rise to a plethora of new exciting molecules with various topologies and functions. This Synpacts article briefly summarizes recent examples of carbon nanohoop dimers, highlighting three examples as nanotube fragments. Their synthesis, isomerization, photophysical properties, and host–guest chemistry are discussed.

1 Introduction

2 Synthetic Strategy toward Nanotube Dimers

3 Isomerization Dynamics of Nanotube Dimers

4 Photophysical Properties of Nanotube Dimers

5 Host–Guest Chemistry of Nanotube Dimers

6 Conclusions
The Role of Exosomes in the Treatment, Prevention, Diagnosis, and Pathogenesis of COVID-19
Authors: Zani-Ruttenstock Elke , Antounians Lina , Khalaj Kasra , Figueira Rebeca L. , Zani Augusto
Published: June 2021

The novel coronavirus disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), continues to be a major health concern. In search for novel treatment strategies against COVID-19, exosomes have attracted the attention of scientists and pharmaceutical companies worldwide. Exosomes are small extracellular vesicles, secreted by all types of cells, and considered as key mediators of intercellular communication and stem-cell paracrine signaling. Herein, we reviewed the most recent literature about the role of exosomes as potential agents for treatment, prevention, diagnosis, and pathogenesis of COVID-19. Several studies and ongoing clinical trials have been investigating the anti-inflammatory, immunomodulatory, and reparative effects of exosomes derived from mesenchymal stem/stromal cells for COVID-19-related acute lung injury. Other studies reported that exosomes play a key role in convalescent plasma therapy for COVID-19, and that they could be of use for the treatment of COVID-19 Kawasaki's-like multisystem inflammatory syndrome and as drug delivery nanocarriers for antiviral therapy. Harnessing some advantageous aspects of exosome biology, such as their endogenous origin, capability of crossing biological barriers, high stability in circulation, and low toxicity and immunogenicity, several companies have been testing exosome-based vaccines against SARS-CoV-2. As they carry cargos that mimic the status of parent cells, exosomes can be isolated from a variety of sources, including plasma, and employed as biomarkers of COVID-19. Lastly, there is growing evidence supporting the role of exosomes in COVID-19 infection, spread, reactivation, and reinfection. The lessons learned using exosomes for COVID-19 will help determine their efficacy and applicability in other clinical conditions.
Impact of the Global COVID-19 Pandemic on the Incidence, Presentation, and Management of Pediatric Appendicitis: Lessons Learned from the First Wave
Authors: Saalabian Kerstin , Rolle Udo , Friedmacher Florian
Published: June 2021

The fast-evolving nature of the coronavirus disease 2019 (COVID-19) pandemic has led to unprecedented clinical, logistical, and socioeconomical challenges for health-care systems worldwide. While several studies have analyzed the impact on the presentation and management of acute appendicitis (AA) in the adult population, there is a relative paucity of similar research in pediatric patients with AA. To date, there is some evidence that the incidence of simple AA in children may have decreased during the first lockdown period in spring 2020, whereas the number of complicated AA cases remained unchanged or increased slightly. Despite a worrying trend toward delayed presentation, most pediatric patients with AA were treated expediently during this time with comparable outcomes to previous years. Hospitals must consider their individual capacity and medical resources when choosing between operative and non-operative management of children with AA. Testing for severe acute respiratory syndrome coronavirus type 2 is imperative in all pediatric patients presenting with fever and acute abdominal pain with diarrhea or vomiting, to differentiate between multisystem inflammatory syndrome and AA, thus avoiding unnecessary surgery. During the further extension of the COVID-19 crisis, parents should be encouraged to seek medical care with their children early in order that the appropriate treatment for AA can be undertaken in a timely fashion.
Optimizing Clinical Monitoring Tools to Enhance Patient Review by Pharmacists
Authors: Schreier Diana J. , Lovely Jenna K.
Published: June 2021

Background The Clinical Monitoring List (CML) is a real-time scoring system and intervention tool used by Mayo Clinic pharmacists caring for hospitalized patients.

Objective The study aimed to describe the iterative development and implementation of pharmacist clinical monitoring tools within the electronic health record at a multicampus health system enterprise.

Methods Between October 2018 and January 2019, pharmacists across the enterprise were surveyed to determine opportunities and gaps in CML functionality. Responses were received from 39% (n = 162) of actively staffing inpatient pharmacists. Survey responses identified three main gaps in CML functionality: (1) the desire for automated checklists of tasks, (2) additional rule logic closely aligning with clinical practice guidelines, and (3) the ability to dismiss and defer rules. The failure mode and effect analysis were used to assess risk areas within the CML. To address identified gaps, two A/B testing pilots were undertaken. The first pilot analyzed the effect of updated CML rule logic on pharmacist satisfaction in the domains of automated checklists and guideline alignment. The second pilot assessed the utility of a Clinical Monitoring Navigator (CMN) functioning in conjunction with the CML to display rules with selections to dismiss or defer rules until a user-specified date. The CMN is a workspace to guide clinical end user workflows; permitting the review and actions to be completed within one screen using EHR functionality.

Results A total of 27 pharmacists across a broad range of practice specialties were selected for two separate two-week pilot tests. Upon pilot completion, participants were surveyed to assess the effect of updates on performance gaps.

Conclusion Findings from the enterprise-wide survey and A/B pilot tests were used to inform final build decisions and planned enterprise-wide updated CML and CMN launch. This project serves as an example of the utility of end-user feedback and pilot testing to inform project decisions, optimize usability, and streamline build activities.
Imaging pyrometry for most color cameras using a triple pass filter
Authors: McNesby Kevin , Dean Steven , Benjamin Richard , Grant Jesse , Anderson James , Densmore John
Published: June 2021

A simple combination of the Planck blackbody emission law, optical filters, and digital image processing is demonstrated to enable most commercial color cameras (still and video) to be used as an imaging pyrometer for flames and explosions. The hardware and data processing described take advantage of the color filter array (CFA) that is deposited on the surface of the light sensor array present in most digital color cameras. In this work, a triple-pass optical filter incorporated into the camera lens allows light in three 10-nm wide bandpass regions to reach the CFA/light sensor array. These bandpass regions are centered over the maxima in the blue, green, and red transmission regions of the CFA, minimizing the spectral overlap of these regions normally present. A computer algorithm is used to retrieve the blue, green, and red image matrices from camera memory and correct for remaining spectral overlap. A second algorithm calibrates the corrected intensities to a gray body emitter of known temperature, producing a color intensity correction factor for the camera/filter system. The Wien approximation to the Planck blackbody emission law is used to construct temperature images from the three color (blue, green, red) matrices. A short pass filter set eliminates light of wavelengths longer than 750 nm, providing reasonable accuracy (±10%) for temperatures between 1200 and 6000 K. The effectiveness of this system is demonstrated by measuring the temperature of several systems for which the temperature is known.
On pointwise decay of waves
Authors: Schlag W.
Published: June 2021

This paper introduces some of the basic mechanisms relating the behavior of the spectral measure of Schrödinger operators near zero energy to the long-term decay and dispersion of the associated Schrödinger and wave evolutions. These principles are illustrated by means of the author’s work on decay of Schrödinger and wave equations under various types of perturbations, including those of the underlying metric. In particular, we consider local decay of solutions to the linear Schrödinger and wave equations on curved backgrounds that exhibit trapping. A particular application is waves on a Schwarzschild black hole spacetime. We elaborate on Price’s law of local decay that accelerates with the angular momentum, which has recently been settled by Hintz, also in the much more difficult Kerr black hole setting. While the author’s work on the same topic was conducted ten years ago, the global semiclassical representation techniques developed there have recently been applied by Krieger, Miao, and the author [“A stability theory beyond the co-rotational setting for critical wave maps blow up,” arXiv:2009.08843 (2020)] to the nonlinear problem of stability of blowup solutions to critical wave maps under non-equivariant perturbations.
Experimental, analytical, and computational investigation of mesh grid thermal physics in an electron gun with dispenser cathode
Authors: Neculaes Bogdan , Frutschy Kristopher , Cross Andrew , Caiafa Antonio
Published: June 2021

Gridded electron guns are key components of various electron beam based vacuum tubes. Mesh grids may be utilized for electron beam extraction and control. As part of the electron beam may be intercepted by the mesh grid, heating occurs, which could translate into performance degradation of the vacuum tube or even failure. This paper introduces an analytical model based on first physics principles for mesh grid heating in an electron gun, toward generating the upper bound for the intercepted electron beam power. 3D simulations and exploratory experiments for mesh grid heating in an electron gun directionally confirm the predictions of the analytical model. This analytical approach may be leveraged further when the upper bounds of mesh grid heating in electron guns are needed, as well as for adjusting mesh grid topology to increase its robustness against electron beam heating.
Photo-dissociation mechanism of trifluoroacetyl chloride in the gas phase: AIMS dynamic simulations
Authors: Hao Yuxia , Liu Lihong , Fang Wei-Hai
Published: June 2021

In this article, the structures and energies of CF3COCl in the low-lying electronic states have been determined by SA-2-CAS(8,7)/6-31G* and SA-2-MSPT2(8,7)/6-31G* calculations, which include equilibrium geometries, transition states, and three minimum-energy conical intersections (CI-1, CI-2, and CI-3) between S0 and S1 states. The AIMS method was used to carry out non-adiabatic dynamic simulations with the ab initio calculation performed at the SA-2-CAS(8,7)/6-31G* level. Upon irradiation to the S1 state, CF3COCl first relaxes to S1 minimum and then overcomes the ∼10 kcal/mol (TSS1_CCl) or ∼30 kcal/mol (TSS1_CO) barrier to the conical intersection region CI-1 or CI-3 (minor), with the S1 → S0 transition probability of 63:1. After non-adiabatic transition to the S0 state through CI-1, trajectories mainly distribute to three different reaction pathways, with one going back to S0 minimum through shortening of the C–Cl bond, the other forming CF3CO and Cl radicals by continuous elongation of the C–Cl distance, and another dissociating into CF3 + CO + Cl and running into the CI-3 region through elongation of C–C and C–Cl distances. Moreover, we found that the trajectories would recross to the S1 state with the recrossing probability of 13.9% through the CI-3 region due to the extremely sloped topographic character of CI-3. On the basis of time evolution of wavefunctions simulated here, the product ratio of CF3 + CO + Cl and CF3CO + Cl is 53.5%:18.4%, which is consistent with the experimental value of 3:1. We further explain the photo-dissociation wavelength dependence of CF3COCl, and the product ratio of CF3 + CO + Cl increases with the increase in total energy.
Efficient interlayer electron transfer in a MoTe2/WS2/MoS2 trilayer heterostructure
Authors: Pan Shudi , Valencia-Acuna Pavel , Kong Weijin , Liu Jianhua , Ge Xiaohui , Xie Wanfeng , Zhao Hui
Published: June 2021

Electron transfer and carrier dynamics in MoTe2/WS2/MoS2 trilayer heterostructures are investigated by transient absorption and photoluminescence measurements. Monolayer flakes of MoTe2, WS2, and MoS2 are obtained by mechanical exfoliation from their bulk crystals and are used to fabricate the heterostructures by a dry-transfer technique. Photoluminescence spectroscopic measurements indicate that the recombination of the MoS2 and WS2 intralayer excitons is significantly suppressed in the heterostructure, illustrating the efficient interlayer charge transfer processes. Layer-selective time-resolved differential reflectance measurements show that the electrons excited in MoTe2 can transfer to MoS2 within 0.3 ps. The transferred electrons show a long lifetime of several hundred picoseconds due to their slow recombination with the spatially separated holes that reside in MoTe2. Furthermore, the charge transfer and recombination processes are weakly dependent on the injected carrier density. These results demonstrate the feasibility of constructing van der Waals multilayer heterostructures involving the infrared-sensitive MoTe2 with emergent properties and provide important information to quantify the performance of MoTe2-based devices.
Enhanced thermodynamic and economic investigation of using heat recovery steam generators for solar thermal power plants
Authors: Biboum Alain Christian , Yilanci Ahmet
Published: June 2021

This study investigates the use of heat recovery steam generators (HRSGs) connected to three types of concentrated solar power (CSP) technologies for solar thermal power plants for the city of Faro-Poli located in northern Cameroon. The HRSGs are designed for the solar thermal power plants using solar tower (ST) technology as HRSG-1 and using parabolic trough collector (PTC) and linear Fresnel reflector (LFR) technologies as HRSG-2. HRSG-1 operates under temperatures between 56.4 and 314.9 °C, whereas HRSG-2 (PTC) and HRSG-2 (LFR) work under temperatures between 57.9 and 264 °C. The exergoeconomic analysis reveals that costs per exergy unit of the solar field system vary from 2.31 to 5.32 $/GJ and that relative cost differences and exergoeconomic factors of HRSG-1 (ST), HRSG-2 (PTC), and HRSG-2 (LFR) are 0.086 and 90.0%, 0.063 and 85.2%, and 0.112 and 72.0%, respectively. The results also show that costs per exergy unit of the HRSGs connected to these three CSP technologies are between 2.41 and 8.41 $/GJ. The avoidable-endogenous exergy destruction values are 158.5, 498.8, and 570.4 kW for HRSG-1 (ST), HRSG-2 (PTC), and HRSG-2 (LFR), respectively. Further, it is seen that HRSG-1 owns the lowest levelized cost rate of product with a value of 0.36 $/h, while the other two HRSG-2 technologies have a value of 1.08 $/h. Finally, the sensitivity analysis shows the cost reduction potential of the HRSGs to make them economically viable. It is concluded that the HRSG-1 (ST) is the most efficient technology considering its impact on the overall exergy efficiency, the levelized cost rate of product, and the cost per exergy unit.
RF wave mixing with sliding charge-density waves
Authors: Nikonov S. A. , Zybtsev S. G. , Pokrovskii V. Ya.
Published: June 2021

We report I–V curves of quasi one-dimensional charge-density wave (CDW) conductors under simultaneous impacts of rf voltage at two frequencies, F and f, with F ≫ f. We find that each Shapiro step (ShS) induced by F-irradiation behaves as a “host” surrounded with “satellites” induced by f-irradiation, e.g., by ShSs at the CDW currents corresponding to F ± f. The subharmonic “hosts” are surrounded with subharmonic “satellites,” e.g., by ShSs at the CDW currents corresponding to F/2 ± f/2. The hosts and satellites show oscillations of their widths as a function of rf amplitude. We demonstrate that each satellite can be treated as a conventional ShS, if its host ShS is taken as a reference point at which the CDW is resting. Thus, with the help of rf irradiation one can emulate CDW samples with tunable threshold voltages and extremely coherent sliding modes.
Mixing in a rotating soft microchannel under electrical double layer effect: A variational calculus approach
Authors: Gaikwad Harshad Sanjay , Mondal Pranab Kumar
Published: June 2021

In this work, we investigate the mixing dynamics of fluid streams in the rotating narrow-fluidic channel having grafted polyelectrolyte layer on its inner wall surfaces. We invoke the variational calculus approach for solving the coupled nonlinear system of transport equations, which is integrated with the non-homogeneous boundary conditions pertinent to this analysis. We obtain the velocity distribution in the asymptotic limit of geostrophic plug flow and then demonstrate the mixing dynamics from the perspective of qualitative assessment as well as quantitative evaluation. Performing the Poincaré map analysis, we predict the mixing of fluid streams from the qualitative assessment, while for the quantification of underlying mixing, we focus on the entropy of mixing analysis. We show that the grafted polyelectrolyte layer at the channel walls modulates the electrical double layer phenomenon following the involved electrostatics. This phenomenon in the presence of an external electric field strengthens the electroosmotic pumping in the fluidic channel non-trivially. Results show that the effects stemming from a larger thickness of the grafted polyelectrolyte layer, that is, the stronger electroosmotic pumping together with a relatively larger magnitude of friction drag, modulate the rotational force-driven primary as well as the secondary flows in the channel. The correlative–cooperative effects of the grafted polyelectrolyte layer on the rotational electrohydrodynamics lead to the formation of the dumbbell-shaped vortex and results in an enhancement in the underlying mixing.
Distinguishing steric and electrostatic molecular probe orientational ordering via their effects on reorientation-induced spectral diffusion
Authors: Hoffman David J. , Fica-Contreras Sebastian M. , Pan Junkun , Fayer Michael D.
Published: June 2021

The theoretical framework for reorientation-induced spectral diffusion (RISD) describes the polarization dependence of spectral diffusion dynamics as measured with two-dimensional (2D) correlation spectroscopy and related techniques. Generally, RISD relates to the orientational dynamics of the molecular chromophore relative to local electric fields of the medium. The predictions of RISD have been shown to be very sensitive to both restricted orientational dynamics (generally arising from steric hindrance) and the distribution of local electric fields relative to the probe (electrostatic ordering). Here, a theory that combines the two effects is developed analytically and supported with numerical calculations. The combined effects can smoothly vary the polarization dependence of spectral diffusion from the purely steric case (least polarization dependence) to the purely electrostatic case (greatest polarization dependence). Analytic approximations of the modified RISD equations were also developed using the orientational dynamics of the molecular probe and two order parameters describing the degree of electrostatic ordering. It was found that frequency-dependent orientational dynamics are a possible consequence of the combined electrostatic and steric effects, providing a test for the applicability of this model to experimental systems. The modified RISD equations were then used to successfully describe the anomalous polarization-dependent spectral diffusion seen in 2D infrared spectroscopy in a polystyrene oligomer system that exhibits frequency-dependent orientational dynamics. The degree of polarization-dependent spectral diffusion enables the extent of electrostatic ordering in a chemical system to be quantified and distinguished from steric ordering.
Designing high-power, octave spanning entangled photon sources for quantum spectroscopy
Authors: Szoke S. , He M. , Hickam B. P. , Cushing S. K.
Published: June 2021

Entangled photon spectroscopy is a nascent field that has important implications for measurement and imaging across chemical, biology, and materials fields. Entangled photon spectroscopy potentially offers improved spatial and temporal-frequency resolutions, increased cross sections for multiphoton and nonlinear measurements, and new abilities in inducing or measuring quantum correlations. A critical step in enabling entangled photon spectroscopies is the creation of high-flux entangled sources that can use conventional detectors as well as provide redundancy for the losses in realistic samples. Here, we report a periodically poled, chirped, lithium tantalate platform that generates entangled photon pairs with ∼10−7 efficiency. For a near watt level diode laser, this results in a near μW-level flux. The single photon per mode limit that is necessary to maintain non-classical photon behavior is still satisfied by distributing this power over up to an octave-spanning bandwidth. The spectral–temporal photon correlations are observed via a Michelson-type interferometer that measures the broadband Hong–Ou–Mandel two-photon interference. A coherence time of 245 fs for a 10 nm bandwidth in the collinear case and a coherence time of 62 fs for a 125 nm bandwidth in the non-collinear case are measured using a CW pump laser and, essentially, collecting the full photon cone. We outline in detail the numerical methods used for designing and tailoring the entangled photons source, such as changing center wavelength or bandwidth, with the ultimate aim of increasing the availability of high-flux UV–Vis entangled photon sources in the optical spectroscopy community.
Entangled-photon interferometry for plasmas
Authors: Wang Zhehui , Shih Yanhua
Published: June 2021

Subpicosecond coincidence timing from nonlocal intensity interference of entangled photons allows quantum interferometry for plasmas. Using a warm plasma dispersion relation, we correlate phase measurement sensitivity with different plasma properties or physics mechanisms over six orders of magnitude. Due to Nα (α≤−1/2) scaling with the photon number N, quantum interferometry using entangled light can probe small signals in plasmas not previously accessible. As an example, it is predicted that plasmas will induce shifts to a Gaussian dip, a well-known quantum optics phenomenon that is yet to be demonstrated for plasmas.
Crystal structure engineering in multimetallic high-index facet nanocatalysts
Authors: Shen Bo , Huang Liliang , Shen Jiahong , He Kun , Zheng Cindy Y. , Dravid Vinayak P. , Wolverton Chris , Mirkin Chad A.
Published: June 2021

Significance

Crystal structure engineering in nanoparticles represents an important strategy in catalyst design, as catalytic performance is highly dependent on atomic arrangement. However, realizing crystal structure engineering in high-index facet nanocatalysts has been a synthetic challenge for decades. Here, we first employed density functional theory calculations to determine whether surface modifications can stabilize high-index facets during crystal structure transformations and then synthesized a library of multimetallic high-index facet tetrahexahedral (THH) nanoparticles with controllable crystal structures. Importantly, the crystal structural transition between the intermetallic and chemically disordered states is reversable, and the THH morphology of nanocatalysts is maintained during this transformation. This approach broadens the synthetic scope of nanocatalysts available for use in diverse chemical processes.
Small stories in short interactions
Authors: Koester Almut
Published: June 2021

The study investigates story-telling in naturally-occurring interactions in a care home for older people with dementia in England. Stories were told by a range of discourse participants and varied from more relationally-oriented anecdotes occurring as part of small talk to more transactionally-oriented narratives embedded into work routines. The main aim of the study was to explore narratives as social practice in the interactions of the care staff and to discover what functions they perform in their workplace practice and more generally in that of the care home. The analysis focused principally on two primarily work-oriented narrative types: “working stories” and “narratives of professional practice”. The findings were that such stories performed a range of key functions in the professional practice of the care givers, in particular problem-solving, knowledge-sharing and critical evaluation.
Migration and regional cooperation for development: ECOWAS in perspective
Authors: Attoh Franca , Ishola Ebenezer
Published: June 2021

The phenomenon of migration involves the movement of people from one milieu to another. Different reasons underscore this movement by people such as escape from conflict, quest for greener pasture, search for employment, and coercion from criminal syndicates. This paper focuses on the dynamics of intraregional migration in West Africa. The importance of migration within West Africa is emphasized in the region’s development agenda, Vision 2020, which places importance on regional resource development. Ease of migration is central to harnessing the region’s human resource potential for development ends. At inception, migration within West Africa was governed by the ECOWAS protocol on free movement of persons, residence, and establishment adopted in 1979. Within this framework, migration is considered as an integral element in the economic integration of the region. Hence, the protocol provides the right of entry for 90 days, residence and establishment for citizens of ECOWAS member countries. The ECOWAS Common Approach on Migration adopted in 2008 currently governs the migration process in the region. In interrogating migration governance in West Africa, this paper identifies challenges, such as, defective state capacities and continued underdevelopment, protectionist policies, language, colonial vestiges, such as, currency, among others, as factors militating against the successful exploitation of the region’s productive population for development ends.
E3 ubiquitin ligase Wwp1 regulates ciliary dynamics of the Hedgehog receptor Smoothened
Authors: Lv Bo , Stuck Michael W. , Desai Paurav B. , Cabrera Oscar A. , Pazour Gregory J.
Published: June 2021

The Hedgehog pathway, critical to vertebrate development, is organized in primary cilia. Activation of signaling causes the Hedgehog receptor Ptch1 to exit cilia, allowing a second receptor, Smo, to accumulate in cilia and activate the downstream steps of the pathway. Mechanisms regulating the dynamics of these receptors are unknown, but the ubiquitination of Smo regulates its interaction with the intraflagellar transport system to control ciliary levels. A focused screen of ubiquitin-related genes identified nine required for maintaining low ciliary Smo at the basal state. These included cytoplasmic E3s (Arih2, Mgrn1, and Maea), a ciliary localized E3 (Wwp1), a ciliary localized E2 (Ube2l3), a deubiquitinase (Bap1), and three adaptors (Kctd5, Skp1a, and Skp2). The ciliary E3, Wwp1, binds Ptch1 and localizes to cilia at the basal state. Activation of signaling removes both Ptch1 and Wwp1 from cilia, thus providing an elegant mechanism for Ptch1 to regulate ciliary Smo levels.
Local memory CD4 T cell niches in respiratory viral infection
Authors: Pruner Kurt B. , Pepper Marion
Published: June 2021

Respiratory viral infections present a major threat to global health and prosperity. Over the past century, several have developed into crippling pandemics, including the SARS-CoV-2 virus. Although the generation of neutralizing serum antibodies in response to natural immunity and vaccination are considered to be hallmarks of viral immune protection, antibodies from long-lived plasma cells are subject to immune escape from heterologous clades of zoonotic, recombined, or mutated viruses. Local immunity in the lung can be generated through resident memory immune subsets that rapidly respond to secondary infection and protect from heterologous infection. Although many immune cells are required to achieve the phenomenon of resident memory, herein we highlight the pleiotropic functions of CD4 tissue resident memory T cells in the lung and discuss the implications of resident memory for vaccine design.
Assessment of occupational exposure from shielded and unshielded syringes for clinically relevant positron emission tomography (PET) isotopes—a Monte Carlo approach using EGSnrc
Authors: McCann Ann , León Vintró Luis , Cournane Seán , Lucey Julie
Published: June 2021

18F has been the most widely used radionuclide in positron emission tomography (PET) facilities over the last few decades. However, increased interest in novel PET tracers, theranostics and immuno-PET has led to significant growth in clinically used positron-emitting radionuclides. The decay schemes of each of these radioisotopes are markedly different from 18F, with different endpoint energies for the emitted positrons and, in some cases, additional high energy gamma radiation. This has implications for the occupational exposure of personnel involved in the manipulation and dispensing of PET radiopharmaceuticals. The EGSnrc Monte Carlo simulation software was used to estimate the doses to extremities in contact with unshielded and shielded syringes containing 64Cu, 18F, 11C, 13N, 15O, 68Ga and 89Zr, respectively. Dose rates at various distances from the syringe were also modelled, with dose rates reported in terms of eye (Hp(3)), skin equivalent (Hp(0.07)) and deep (Hp(10)) doses. The composition and geometry of the simulated syringe shields were based on a selection of commercially available PET shields. Experimental dose rate measurements were performed for validation purposes where possible. Contact skin dose rates for all isotopes, except for 64Cu, were found to be higher than 18F for the unshielded syringe. The addition of a shield resulted in approximately equal contact skin dose rates for nearly all isotopes, for each shield type, with the exception of 89Zr which was notably higher. Dose rate constants (µGy/MBq.hr) for a range of PET isotopes and shields are presented and their significance discussed.
On mix-norms and the rate of decay of correlations
Authors: Oakley Bryan W , Thiffeault Jean-Luc , Doering Charles R
Published: June 2021

Two quantitative notions of mixing are the decay of correlations and the decay of a mix-norm—a negative Sobolev norm—and the intensity of mixing can be measured by the rates of decay of these quantities. From duality, correlations are uniformly dominated by a mix-norm; but can they decay asymptotically faster than the mix-norm? We answer this question by constructing an observable with correlation that comes arbitrarily close to achieving the decay rate of the mix-norm. Therefore the mix-norm is the sharpest rate of decay of correlations in both the uniform sense and the asymptotic sense. Moreover, there exists an observable with correlation that decays at the same rate as the mix-norm if and only if the rate of decay of the mix-norm is achieved by its projection onto low-frequency Fourier modes. In this case, the function being mixed is called q
-recurrent; otherwise it is q-transient. We use this classification to study several examples and raise questions for future investigations.
Mixing rates for symplectic almost Anosov maps
Authors: Eslami Peyman , Liverani Carlangelo
Published: June 2021

We establish sharp bounds on the mixing rates of a class of two dimensional non-uniformly hyperbolic symplectic maps. This provides a primer on how to investigate such questions in a concrete example and, at the same time, it solves a controversy between previous rigorous results and numerical experiments.
Variational methods for breather solutions of nonlinear wave equations
Authors: Mandel Rainer , Scheider Dominic
Published: June 2021

We construct infinitely many real-valued, time-periodic breather solutions of the nonlinear wave equation

∂

t
t

U
−
Δ
U
=
Q

(

x

)

|
U

|

p
−
2

U

on

T
×

R

N

with suitable N ⩾ 2, p > 2 and localized nonnegative Q. These solutions are obtained from critical points of a dual functional and they are weakly localized in space. Our abstract framework allows to find similar existence results for the nonlinear Klein–Gordon equation and biharmonic wave equations.
The Dubrovin threefold of an algebraic curve
Authors: Agostini Daniele , Çelik Türkü Özlüm , Sturmfels Bernd
Published: June 2021

The solutions to the Kadomtsev–Petviashvili equation that arise from a fixed complex algebraic curve are parametrized by a threefold in a weighted projective space, which we name after Boris Dubrovin. Current methods from nonlinear algebra are applied to study parametrizations and defining ideals of Dubrovin threefolds. We highlight the dichotomy between transcendental representations and exact algebraic computations. Our main result on the algebraic side is a toric degeneration of the Dubrovin threefold into the product of the underlying canonical curve and a weighted projective plane.
Symmetry of positive solutions of elliptic equations with mixed boundary conditions in a sub-spherical sector
Authors: Chen Hongbin , Li Rui , Yao Ruofei
Published: June 2021

The paper is devoted to the qualitative properties of positive solutions to a semilinear elliptic equation in a planar sub-spherical sector. Under certain range of amplitudes, we prove some monotonicity properties via the method of moving planes. The symmetry properties follow from the uniqueness of the corresponding over-determined problem by Farina and Valdinoci (2013 Am. J. Math.).
Effects on I–V relations from small permanent charge and channel geometry via classical Poisson–Nernst–Planck equations with multiple cations
Authors: Wen Zhenshu , Bates Peter W , Zhang Mingji
Published: June 2021

We analyse a quasi-one-dimensional Poisson–Nernst–Planck system for ionic flow through a membrane channel with nonzero but small permanent charge. The system includes three ion species, two cations with the same valences and one anion. The cross-sectional area of the channel is included in the system, which provides certain information of the geometry of the three-dimensional channel. This is critical for our analysis. We treat the model as a boundary value problem of a singularly perturbed system of differential equations. Under the framework of geometric singular perturbation theory, together with specific structures of the model, the existence and local uniqueness of solutions to the boundary value problem for small permanent charges is established. Furthermore, treating the permanent charge as a small parameter, via regular perturbation analysis, we are able to derive an approximation of the I–V (current–voltage) relations explicitly, from which the permanent charge and channel geometry effects on ionic flows are analysed in detail. Critical potentials are identified and their roles in characterising the ionic flow properties of interest are studied. Some critical potentials can be experimentally estimated, and this provides an efficient way to adjust the boundary pot to observe distinct dynamics of ionic flows. Mathematical analysis indicates that a short and narrow filter within which the permanent charge is confined is expected in order to optimise the effect of permanent charges. This is consistent with the typical structure of an ion channel.
Invariant measures of fractional stochastic delay reaction–diffusion equations on unbounded domains
Authors: Chen Zhang , Wang Bixiang
Published: June 2021

In this paper, existence of invariant measure is mainly investigated for a fractional stochastic delay reaction–diffusion equation defined on unbounded domains. We first establish the mean-square uniform smallness of the tails of the solutions in order to overcome the non-compactness of standard Sobolev embeddings on unbounded domains. We then show the weak compactness of a family of probability distributions of the solutions by combining the Ascoli–Arzelà theorem, the uniform tail-estimates as well as the technique of dyadic division.
Normalized solutions for fractional nonlinear scalar field equations via Lagrangian formulation
Authors: Cingolani S , Gallo M , Tanaka K
Published: June 2021

We study existence of solutions for the fractional problem

(

P

m

)

(

−
Δ

)

s

u
+
μ
u
=
g

(

u

)

in

R

N

,

∫

R

N

u

2

d
x
=
m
,

u
∈

H

r

s

(

R

N

)

,

where N ⩾ 2, s ∈ (0, 1), m > 0, μ is an unknown Lagrange multiplier and

g
∈
C

(

R
,
R

)

satisfies Berestycki–Lions type conditions. Using a Lagrangian formulation of the problem (P

m
), we prove the existence of a weak solution with prescribed mass when g has L
2 subcritical growth. The approach relies on the construction of a minimax structure, by means of a Pohozaev’s mountain in a product space and some deformation arguments under a new version of the Palais–Smale condition introduced in Hirata and Tanaka (2019 Adv. Nonlinear Stud.
19 263–90); Ikoma and Tanaka (2019 Adv. Differ. Equ.
24 609–46). A multiplicity result of infinitely many normalized solutions is also obtained if g is odd.
Existence, uniqueness and regularity for the stochastic Ericksen–Leslie equation
Authors: De Bouard Anne , Hocquet Antoine , Prohl Andreas
Published: June 2021

We investigate existence and uniqueness for the liquid crystal flow driven by colored noise on the two-dimensional torus. After giving a natural uniqueness criterion, we prove local solvability in L

p
-based spaces, for every p > 2. Thanks to a bootstrap principle together with a Gyöngy–Krylov-type compactness argument, this will ultimately lead us to prove the existence of a particular class of global solutions which are partially regular, strong in the probabilistic sense, and taking values in the ‘critical space’ L
2 × H
1.
Smoothing of nonsmooth differential systems near regular-tangential singularities and boundary limit cycles
Authors: Novaes Douglas D , Rondón Gabriel
Published: June 2021

Understanding how tangential singularities evolve under smoothing processes was one of the first problem concerning regularization of Filippov systems. In this paper, we are interested in C

n
-regularizations of Filippov systems around visible regular-tangential singularities of even multiplicity. More specifically, using Fenichel theory and blow-up methods, we aim to understand how the trajectories of the regularized system transits through the region of regularization. We apply our results to investigate C

n
-regularizations of boundary limit cycles with even multiplicity contact with the switching manifold.
Equilibrium states for maps isotopic to Anosov
Authors: Álvarez Carlos F , Sánchez Adriana , Varão Régis
Published: June 2021

In this work we address the problem of existence and uniqueness (finiteness) of ergodic equilibrium states for partially hyperbolic diffeomorphisms isotopic to Anosov on

T

4

, with two-dimensional center foliation. To do so we propose to study the disintegration of measures along one-dimensional subfoliations of the center bundle. Moreover, we obtain a more general result characterizing the disintegration of ergodic measures in our context.
Spin and polarization effects on the nonlinear Breit–Wheeler pair production in laser-plasma interaction
Authors: Song Huai-Hang , Wang Wei-Min , Li Yan-Fei , Li Bing-Jun , Li Yu-Tong , Sheng Zheng-Ming , Chen Li-Ming , Zhang Jie
Published: June 2021

The spin effect of electrons/positrons (e
−/e
+) and polarization effect of γ photons are investigated in the interaction of two counter-propagating linearly polarized laser pulses of peak intensity 8.9 × 1023 W cm−2 with a thin foil target. The processes of nonlinear Compton scattering and nonlinear Breit–Wheeler pair production based on the spin- and polarization-resolved probabilities are implemented into the particle-in-cell (PIC) algorithm by Monte Carlo methods. It is found from PIC simulations that the average degree of linear polarization of emitted γ photons can exceed 50%. This polarization effect leads to a reduced positron yield by about 10%. At some medium positron energies, the reduction can reach 20%. Furthermore, we also observe that the local spin polarization of e
−/e
+ leads to a slight decrease of the positron yield about 2% and some anomalous phenomena about the positron spectrum and photon polarization at the high-energy range, due to spin-dependent photon emissions. Our results indicate that spin and polarization effects should be considered in calculating the pair production and laser-plasma interaction with the laser power of 10 PW to 100 PW classes.
Hearing Higgs with gravitational wave detectors
Authors: Salvio Alberto
Published: June 2021

The relic gravitational wave background due to tensor linear perturbations generated during Higgs inflation is computed. Both the Standard Model and a well-motivated phenomenological completion (that accounts for all the experimentally confirmed evidence of new physics) are considered. We focus on critical Higgs inflation, which improves on the non-critical version and features an amplification of the tensor fluctuations. The latter property allows us to establish that future space-borne interferometers, such as DECIGO, BBO and ALIA, may detect the corresponding primordial gravitational waves.
Microcrack localization using a collinear Lamb wave frequency-mixing technique in a thin plate
Authors: Wang Ji-Shuo , Xu Cai-Bin , Zhao You-Xuan , Hu Ning , Deng Ming-Xi
Published: June 2021

A novel Lamb wave frequency-mixing technique is proposed for locating microcracks in a thin plate, which does not require the resonance condition of Lamb wave mixing and can accurately locate the microcracks through only one-time sensing. Based on the bilinear stress-strain constitutive model, a two-dimensional finite element (FE) model is built to investigate the frequency-mixing response induced by the interaction between two primary Lamb waves and a microcrack. When twoprimary Lamb waves of A0 and S0 modes with different frequencies excited on the same side of the plate simultaneously impinge on the examined microcrack, under the modulation of the contact acoustic nonlinearity, the microcrack itself can be deemed as the secondary sound source and it will radiate the Lamb waves of new combined frequencies. Based on the timeof flight of the generated A0 mode at difference frequency, an indicator named normalized amplitude index (NAI) is defined to directly locate the multi-microcracks in the given plate. It is found that the number and location of the microcracks can be intuitively visualized by using the NAI based frequency-mixing technique. It is also demonstrated that the proposed frequency mixing technique is a promising approach for the microcrack localization.
Controlled plasmon-enhanced fluorescence by spherical microcavity*
Authors: Zhao Jingyi , Zhang Weidong , Wen Te , Ye Lulu , Lin Hai , Tang Jinglin , Gong Qihuang , Lyu Guowei
Published: June 2021

A surrounding electromagnetic environment can engineer spontaneous emissions from quantum emitters through the Purcell effect. For instance, a plasmonic antenna can efficiently confine an electromagnetic field and enhance the fluorescent process. In this study, we demonstrate that a photonic microcavity can modulate plasmon-enhanced fluorescence by engineering the local electromagnetic environment. Consequently, we constructed a plasmon-enhanced emitter (PE-emitter), which comprised a nanorod and a nanodiamond, using the nanomanipulation technique. Furthermore, we controlled a polystyrene sphere approaching the PE-emitter and investigated in situ the associated fluorescent spectrum and lifetime. The emission of PE-emitter can be enhanced resonantly at the photonic modes as compared to that within the free spectral range. The spectral shape modulated by photonic modes is independent of the separation between the PS sphere and PE-emitter. The band integral of the fluorescence decay rate can be enhanced or suppressed after the PS sphere couples to the PE-emitters, depending on the coupling strength between the plasmonic antenna and the photonic cavity. These findings can be utilized in sensing and imaging applications.