bluuebunny/crossref_metadata_2025 huggingface dataset:
Laser ultrasonic nondestructive evaluation of sub-millimeter-level crack growth in the rail foot weld
Authors: Ren Guanpin , Sun Zhongrui , Dai Xinyi , Liu Shuang , Zhang Xiaoqin , Chen Xiaofeng , Yan Min , Liu Shuang
Published: July 2022

Laser-generated ultrasonic wave characteristics in the rail foot weld were simulated and reported for qualitative analysis and evaluation of sub-millimeter-level crack growth. Numerical analyses using the finite element method (FEM), the propagation characteristics, and displacement field distribution of a laser-generated ultrasonic wave after the interaction with cracks were fully demonstrated. By calculating displacement amplitude distribution, the optimal sensing position and area were the laser incident point and the upper surface, respectively. Crack growth degree toward the rail bottom and axial direction can be confirmed by analyzing time and amplitude of the echoes originating from the rail bottom and crack surface reflection. By combining time with peak intensity of the echo reflection from the rail bottom, the sub-millimeter-level crack growth process inside the rail foot weld is capable of acquiring and evaluating. The results justify that the laser ultrasonic technique, characterized by laser excitation and laser detection, is a competitive nondestructive testing technique for sub-millimeter-level crack growth evaluation and detection inside the rail foot weld.
Collision-free distributed MAC protocol for passive optical intra-rack data center networks
Authors: Baziana Peristera , Drainakis Georgios
Published: July 2022

In this paper, we present a distributed medium access control (MAC) protocol and a network architecture suitable for optical intra-rack data center networks (DCNs). The intra-rack communication is performed using passive optical components, over four data wavelength division multiplexing (WDM) channels of either 40 or 100 Gbps each, keeping low power consumption. On the other hand, the inter-rack communication is performed over a separate network through upper layer routers. In this study, we focus only on the intra-rack communication. We introduce an intra-rack DCN (IR-DCN) architecture that works in the optical domain, and two IR-DCN configurations with different total nominal capacity: 160 and 400 Gbps, respectively. Also, we propose a synchronous pre-transmission coordination fair access intra-rack MAC (intra-MAC) protocol taking into account the traffic characteristics and priority classes within existing DCNs. The proposed intra-MAC protocol totally eliminates packet collisions, achieving high performance. Particularly, it reaches high bandwidth utilization even under heavy loads: 90% and 87.5% for the two IR-DCN configurations of 160 and 400 Gbps total capacity, respectively. Also, it achieves low mean end-to-end (e2e) packet delay, lower than 0.25 and 0.12 ms, respectively, providing a reliable solution for time-sensitive DCN traffic. Specifically, simulation results demonstrate that the highest priority traffic experiences e2e delay lower than 1.9 and 1.1 µs, respectively, which is sufficient for the service of the strictest delay requirements of time-sensitive cloud applications. The intra-MAC protocol is decentralized, without the need for a network controller, providing high flexibility. Our IR-DCN proposal is studied in comparison to other currently dominant intra-rack/cluster DCNs, and it achieves from 6% to 57% higher throughput and from 20% to 99% lower e2e delay at high loads. Comparatively, it is on average 80% and 68% more energy and cost efficient, respectively.
Optimizing sampling for surface localization in 3D-scanning microscopy
Authors: Burcklen Marie-Anne , Galland Frédéric , Le Goff Loïc
Published: July 2022

3D-scanning fluorescence imaging of living tissue is in demand for less phototoxic acquisition process. For the imaging of biological surfaces, adaptive and sparse scanning schemes have been proven to efficiently reduce the light dose by concentrating acquisitions around the surface. In this paper, we focus on optimizing the scanning scheme at a constant photon budget, when the problem is to estimate the position of a biological surface whose intensity profile is modeled as a Gaussian shape. We propose an approach based on the Cramér–Rao bound to optimize the positions and number of scanning points, assuming signal-dependant Gaussian noise. We show that, in the case of regular sampling, the optimization problem can be reduced to a few parameters, allowing us to define quasi-optimal acquisition strategies, first when no prior knowledge of the surface location is available and then when the user has a prior on this location.
Investigation of quadrature squeezing in parametric downconversion with a partially coherent pump
Authors: Rao Sakshi , Sharma Preeti , Kanseri Bhaskar
Published: July 2022

We investigate the behavior of squeezing in combined quadratures of biphotons generated in the parametric downconversion process for partially coherent pump beams in spatial, temporal, and spatiotemporal domains compared to fully coherent beams. These beams involve both stationary (continuous-wave) and non-stationary (pulsed) processes. This study also involves the derivation of complex Gaussian representation for a partially spatially coherent pump modeled as a Gaussian Schell model beam, which is more resistant to the effects of turbulence. Our findings illustrate that by employing the partially coherent pump, one can generate a squeezed state possessing partially coherent properties without compromising in squeezing by optimizing pump field amplitude, interaction length, and degree of coherence of the pump. We anticipate these results to be useful in limiting the possibility of eavesdropping in noisy channels and optical high-precision measurements in the case of continuous-variable quantum key distribution based on two-mode squeezed states.
Superpixel-based sub-hologram method for real-time color three-dimensional holographic display with large size
Authors: Ma Haowen , Wei Chenxiao , Wei Jiahao , Han Yu , Pi Dapu , Yang Yan , Zhao Weirui , Wang Yongtian , Liu Juan
Published: July 2022

One of the biggest challenges for large size three-dimensional (3D) holographic display based on the computer-generated hologram (CGH) is the trade-off between computation time and reconstruction quality, which has limited real-time synthesis of high-quality holographic image. In this paper, we propose a superpixel-based sub-hologram (SBS) method to reduce the computation time without sacrificing the quality of the reconstructed image. The superpixel-based sub-hologram method divides the target scene into a collection of superpixels. The superpixels are composed of adjacent object points. The region of the superpixel-based sub-hologram corresponding to each superpixel is determined by an approximation method. Since the size and the complexity of the diffraction regions are reduced, the hologram generation time is decreased significantly. The computation time has found to be reduced by 94.89% compared with the conventional sub-hologram method. It is shown that the proposed method implemented on the graphics processing unit (GPU) framework can achieve real-time (> 24 fps) color three-dimensional holographic display with a display size of 155.52 mm × 276.48 mm.
Large aperture high diffraction efficiency off-axis Fresnel lens fabrication and analysis
Authors: Gao Guohan , Shi Heng , Wang Lihua , Liu Dun , Wang Jiong , Du Junfeng , Bian Jiang , Fan Bin , Yang Hu
Published: July 2022

Large aperture high diffraction efficiency off-axis Fresnel lens is one of the most important optical elements in future 10m scale aperture transmissive space telescope systems. Improving diffraction efficiency and effective aperture are long-term goals and bottlenecks for engineering applications. A 4-level off-axis fresnel lens with Ф350 mm effective aperture and 2 µm critical dimension was fabricated through overlay etching technique bylaser direct writing system. Average diffraction efficiency of 75.9% was achieved and certain distribution pattern was observed. Influence of alignment errors on diffraction efficiency distribution was analysed and discussed in detail. This work presented the best results to our knowledge among the same field with similar aperture and critical dimension in open publications, and layed a solid foundation for future large aperture diffractive telescope development.
Anisotropic coding metasurfaces and their active manipulation based on vanadium dioxide for multifunctional applications in the terahertz region
Authors: Liu Shilei , Ouyang Chunmei , Yao Zhibo , Zhao Jing , Li Yanfeng , Feng Longcheng , Zhang Caihong , Jin Biaobing , Ma Jiajun , Li Hongyi , Liu Yi , Xu Quan , Han Jiaguang , Zhang Weili
Published: July 2022

Various kinds of metasurfaces have been proposed because they can be tailored to achieve the desired modulations on electromagnetic wave that do not occur in nature. Compared to conventional metamaterials, coding metasurfaces integrated with information science theory possess numerous distinctive advantages - simple design, time-saving and compatibility with digital devices. Here we propose terahertz multifunctional anisotropic reflective metasurfaces with a metal-insulator-metal cavity structure whose top constructional layer consists of a pair of gold arc-rings and a gold cut-wire located between them. Two different functions of narrow-band absorption and broadband polarization conversion are realized based on different coding matrices using the binary codes ‘0’ and ‘1’. Furthermore, we integrate a specific coding metasurface with vanadium dioxide (VO2) to realize a temperature-controlled active metasurface. Through the temperature change, dynamic functionalities switching between a narrow-band polarization converter with a polarization conversion ratio over 94% and an efficient low-pass filter are achieved under the phase transition of VO2, and the active metasurface is polarization independent. The proposed coding metasurfaces are verified numerically and experimentally, and have promising applications in terahertz modulation and functional devices.
RETRACTED: Single-shot 3D shape measurement based on RGB dot patterns and stereovision
Authors: Lu Yang , Wang Zihao , Yu Liandong , Jia Huakun , Chen Xiaozhe , Gao Rongke , Li Haiju , Wang Yeru , Ma Chao
Published: July 2022

One-shot projection structured light 3D measurement is a method to establish the stereo matching relationship and reconstruct 3D shape by projecting one pattern. However, the traditional stereo matching algorithm does not solve the problem of low matching accuracy and matching efficiency, which fundamentally limits the accuracy of 3D measurement. As the projector and imaging systems have daily higher resolution and imaging quality, RGB dots projection has more application prospects because of its ability to establish a stereo matching relationship through one projection. In this work, we proposed a single-shot 3D measurement method using line clustering stereo matching, and model correction methods. The projected RGB dots are extracted by slope differenced distribution and area constrained erosion method. Area constrained erosion can solve the problem of the segmented connected blobs caused by insufficient projection resolution. The clustering stereo matching method is utilized to coarse match the segmented center red points. A model correction method is utilized to restore and constrain the pattern that cannot be imaged. Experimental results demonstrated that our method achieves the best accuracy of about 0.089mm, better than the traditional disparity and RGB line method, which may shed light on the proposed method can accurately reconstruct the 3D surface.
Direct generation of orbital angular momentum in orthogonal fiber Bragg grating
Authors: Liu Rui , Li Yali , Chen Jiayan , Wu Luping , Ran Jianjun , Chen Zikai , Bai Zhiyong , Huang Churou , Huang Zheng , Zhu Guoxuan , Liao Changrui , Wang Yiping
Published: July 2022

We experimentally demonstrated an all-fiber reflective orbital angular momentum (OAM) generator based on orthogonal fiber Bragg grating (OFBG). The OFBG is formed by using a femtosecond laser to prepare two fiber Bragg gratings with a certain spacing in orthogonal planes. The ±1st- and ±2nd-order OAM modes were directly excited in this OFBG, and the chirality of the OAM modes depends on the relative positions of the two FBGs. The mode coupling properties and effects of center-to-center distance on OAM modes were investigated as well.
Non-line-of-sight imaging in the presence of scattering media using phasor fields
Authors: Luesia Pablo , Crespo Miguel , Jarabo Adrian , Redo-Sanchez Albert
Published: July 2022

Non-line-of-sight (NLOS) imaging aims to reconstruct partially or
completely occluded scenes. Recent approaches have demonstrated
high-quality reconstructions of complex scenes with arbitrary
reflectance, occlusions, and significant multi-path effects. However,
previous works focused on surface scattering only, which reduces the
generality in more challenging scenarios such as scenes submerged in
scattering media. In this work, we investigate current
state-of-the-art NLOS imaging methods based on phasor fields to reconstruct scenes submerged in scattering
media. We empirically analyze the capability of phasor fields in
reconstructing complex synthetic scenes submerged in thick scattering
media. We also apply the method to real scenes, showing that it
performs similarly to recent diffuse optical tomography methods.
Raman-induced frequency shift of pure quartic solitons in optical fiber with quartic dispersion
Authors: Wang Zhiteng , Luo Chanyou , Wang Youwen , Ling Xiaohui , Zhang Lifu
Published: July 2022

We investigate the impact of Raman scattering on pure quartic solitons (PQSs) in an optical fiber with quartic dispersion. An analytical expression of the Raman-induced frequency shift (RIFS) of a PQS is obtained by using the variational approach with the Gaussian function ansatz. We find the RIFS of a PQS is inversely proportional to the sixth power of pulse width, when the fiber is short enough. The RIFS of a PQS is more sensitive to the pulse width, compared with that of a conventional soliton which is inversely proportional to the fourth power of pulse width. The theoretical predictions show good agreement with numerical results. In addition, we also discuss the RIFS of the other three typical pulses with the same peak power and pulse width as the PQS. These results provide a thorough understanding of the role of higher-order nonlinear effects on the propagation dynamics of PQSs.
Rapid fabrication of large-area concave microlens arrays on silica glasses by femtosecond laser bursts
Authors: Wang Quanji , Yang Shaorui , Yang Zijing , Duan Jun , Xiong Wei , Deng Leimin
Published: July 2022

An efficient and flexible method using femtosecond laser bursts assisted by wet etching is presented to fabricate large-area high-quality microlens arrays (MLAs) on a silica glass surface. In this method, femtosecond laser bursts can ablate micro craters on silica glass in a fast, single-step process by controlling the electron density and a high-speed scanning galvanometer, and the influence mechanism of the number of pulses within a burst on the accuracy and quality of micro craters is analyzed in detail. The experimental results show that the preparation efficiency of micro craters is significantly improved to approximately 32,700 per second. By subsequent acid etching, concave microlenses with controllable dimensions, shapes, and alignments are easily obtained. A large area close-packed hexagonal concave MLA is successfully fabricated by using this method and shows high surface quality and uniformity, which excellently demonstrates the feasibility and flexibility of rapidly fabricating MLAs in the burst regime.
Structured transverse modes governed by maximum entropy principle
Authors: Tung J. C. , Ke H. T. , Liang H. C. , Huang K. F. , Chen Y. F.
Published: July 2022

Based on the birefringent effect of the gain medium, a diode-pumped Nd-doped vanadate laser with nearly hemispherical cavity is exploited to emulate the quantum Green functions of two-dimensional commensurate harmonic oscillators. By matching the theoretical calculations to the far-field patterns of lasing modes, the resonant transverse frequencies can be accurately determined up to extremely high orders. The Shannon entropy is further employed to calculate the spatial entanglement of the quantum Green function as a function the transverse frequency. From the resonant transverse frequencies, all lasing modes are confirmed to be in excellent agreement with the maximum entropy states. This discovery implies that the formation of lasing modes is relevant to the coupling interaction between the pump source and the laser cavity.
Polarization discrimination and surface sensing with a near-IR nanostructured hybrid mirror
Authors: Buchnev Oleksandr , Belosludtsev Alexandr , Fedotov Vassili A.
Published: July 2022

We demonstrate experimentally how to turn a conventional distributed
Bragg reflector into a polarization selecting mirror operating in the
near-IR at normal incidence without diffraction and with high
extinction ratio. Our approach involves combining a dielectric
multilayer composite with a sub-wavelength metal wire-grid
nanograting, which can be routinely fabricated using well-established
planar fabrication techniques. Moreover, the design and working
principle of our nanostructured hybrid mirror enable it to operate as
a surface sensor and allow straightforward integration of the mirror
with functional materials for tuning its wavelength/polarization
extinction ratio.
Narrow bandwidth spatiotemporal mode-locked Yb-doped fiber laser
Authors: Zhao Tian-Xu , Liu Guang-Xin , Dai Li-long , Zhao Bang , Cui Hu , Mou Cheng-Bo , Luo Zhi-Chao , Xu Wen-Cheng , Luo Ai-Ping
Published: July 2022

We report a narrow bandwidth spatiotemporal mode-locked (STML) ytterbium-doped fiber laser, based on a homemade carbon nanotube/polyvinyl alcohol composite film and the multimode interference filtering effect. The wavelength-tunable narrow bandwidth STML operations combined with different pulse states are achieved, including single pulse, multiple pulses, and harmonics. The 3-dB bandwidth at the single-pulse state is 103 pm, while at the harmonic state, it is as narrow as 26 pm. To give an insight into the generation of the narrow bandwidth STML pulses, numerical simulations are performed. Such a laser has a wide range of potential applications in fields of optical communication and optical measurement, as well as provides a favorable platform for studying the evolution dynamics of multimode solitons.
Valley control by linearly polarized laser pulses: example of WSe2
Authors: Sharma S. , Elliott P. , Shallcross S.
Published: July 2022

Electrons at the band edges of materials are endowed with a valley index, a quantum number locating the band edge within the Brillouin zone. An important question is then how this index may be controlled by laser pulses, with current understanding that it couples exclusively via circularly polarized light. Employing both tight-binding and state-of-the-art time dependent density function theory, we show that on femtosecond time scales valley coupling is a much more general effect. We find that two time separated linearly polarized pulses allow almost complete control over valley excitation, with the pulse time difference and polarization vectors emerging as key parameters for valley control. Our findings highlight the possibility of controlling coherent electronic excitation by successive femtosecond laser pulses, and offer a route towards valleytronics in two-dimensional materials.
Recommendations for empowering early career researchers to improve research culture and practice
Authors: Kent Brianne A. , Holman Constance , Amoako Emmanuella , Antonietti Alberto , Azam James M. , Ballhausen Hanne , Bediako Yaw , Belasen Anat M. , Carneiro Clarissa F. D. , Chen Yen-Chung , Compeer Ewoud B. , Connor Chelsea A. C. , Crüwell Sophia , Debat Humberto , Dorris Emma , Ebrahimi Hedyeh , Erlich Jeffrey C. , Fernández-Chiappe Florencia , Fischer Felix , Gazda Małgorzata Anna , Glatz Toivo , Grabitz Peter , Heise Verena , Kent David G. , Lo Hung , McDowell Gary , Mehta Devang , Neumann Wolf-Julian , Neves Kleber , Patterson Mark , Penfold Naomi C. , Piper Sophie K. , Puebla Iratxe , Quashie Peter K. , Quezada Carolina Paz , Riley Julia L. , Rohmann Jessica L. , Saladi Shyam , Schwessinger Benjamin , Siegerink Bob , Stehlik Paulina , Tzilivaki Alexandra , Umbers Kate D. L. , Varma Aalok , Walavalkar Kaivalya , de Winde Charlotte M. , Zaza Cecilia , Weissgerber Tracey L.
Published: July 2022

Early career researchers (ECRs) are important stakeholders leading efforts to catalyze systemic change in research culture and practice. Here, we summarize the outputs from a virtual unconventional conference (unconference), which brought together 54 invited experts from 20 countries with extensive experience in ECR initiatives designed to improve the culture and practice of science. Together, we drafted 2 sets of recommendations for (1) ECRs directly involved in initiatives or activities to change research culture and practice; and (2) stakeholders who wish to support ECRs in these efforts. Importantly, these points apply to ECRs working to promote change on a systemic level, not only those improving aspects of their own work. In both sets of recommendations, we underline the importance of incentivizing and providing time and resources for systems-level science improvement activities, including ECRs in organizational decision-making processes, and working to dismantle structural barriers to participation for marginalized groups. We further highlight obstacles that ECRs face when working to promote reform, as well as proposed solutions and examples of current best practices. The abstract and recommendations for stakeholders are available in Dutch, German, Greek (abstract only), Italian, Japanese, Polish, Portuguese, Spanish, and Serbian.
Trial-by-trial predictions of subjective time from human brain activity
Authors: Sherman Maxine T. , Fountas Zafeirios , Seth Anil K. , Roseboom Warrick
Published: July 2022

Human experience of time exhibits systematic, context-dependent deviations from clock time; for example, time is experienced differently at work than on holiday. Here we test the proposal that differences from clock time in subjective experience of time arise because time estimates are constructed by accumulating the same quantity that guides perception: salient events. Healthy human participants watched naturalistic, silent videos of up to 24 seconds in duration and estimated their duration while fMRI was acquired. We were able to reconstruct trial-by-trial biases in participants’ duration reports, which reflect subjective experience of duration, purely from salient events in their visual cortex BOLD activity. By contrast, salient events in neither of two control regions–auditory and somatosensory cortex–were predictive of duration biases. These results held despite being able to (trivially) predict clock time from all three brain areas. Our results reveal that the information arising during perceptual processing of a dynamic environment provides a sufficient basis for reconstructing human subjective time duration.
Self-assessment of the home environment to plan for successful ageing: Report from a digital health co-design workshop
Authors: Laver Kate , Davis Aaron , Gwilt Ian , Dalistan Roslyn , Lane Rachel , Block Heather
Published: July 2022

Many middle aged and older people will need to adapt or modify their home in order to age in place. Arming older people and their families with the knowledge and tools to assess their home and plan simple modifications ahead of time will decrease reliance on professional assessment. The objective of this project was to co-design a tool which enables people to assess their own home environment and make future plans for ageing in the home. We recruited members of the public who were aged 60 or older to attend a series of two co-design workshops. Thirteen participants worked through a series of discussions and activities including appraising different types of tools available and mapping what a digital health tool might look like. Participants had a good understanding of the main types of home hazards in their own homes and the types of modifications which may be useful. Participants believed the concept of the tool would be worthwhile and identified a number of features which were important including a checklist, examples of good design which was both accessible and aesthetically pleasing and links to other resources such as websites which provide advice about to make basic home improvements. Some also wanted to share the results of their assessment with family or friends. Participants highlighted that features of the neighbourhood, such as safety and proximity to shops and cafes, were also important when considering the suitability of their home for ageing in place. Findings will be used to develop a prototype for usability testing.
Evaluating indirect genetic effects of siblings using singletons
Authors: Howe Laurence J. , Evans David M. , Hemani Gibran , Davey Smith George , Davies Neil M.
Published: July 2022

Estimating effects of parental and sibling genotypes (indirect genetic effects) can provide insight into how the family environment influences phenotypic variation. There is growing molecular genetic evidence for effects of parental phenotypes on their offspring (e.g. parental educational attainment), but the extent to which siblings affect each other is currently unclear. Here we used data from samples of unrelated individuals, without (singletons) and with biological full-siblings (non-singletons), to investigate and estimate sibling effects. Indirect genetic effects of siblings increase (or decrease) the covariance between genetic variation and a phenotype. It follows that differences in genetic association estimates between singletons and non-singletons could indicate indirect genetic effects of siblings if there is no heterogeneity in other sources of genetic association between singletons and non-singletons. We used UK Biobank data to estimate polygenic score (PGS) associations for height, BMI and educational attainment in self-reported singletons (N = 50,143) and non-singletons (N = 328,549). The educational attainment PGS association estimate was 12% larger (95% C.I. 3%, 21%) in the non-singleton sample than in the singleton sample, but the height and BMI PGS associations were consistent. Birth order data suggested that the difference in educational attainment PGS associations was driven by individuals with older siblings rather than firstborns. The relationship between number of siblings and educational attainment PGS associations was non-linear; PGS associations were 24% smaller in individuals with 6 or more siblings compared to the rest of the sample (95% C.I. 11%, 38%). We estimate that a 1 SD increase in sibling educational attainment PGS corresponds to a 0.025 year increase in the index individual’s years in schooling (95% C.I. 0.013, 0.036). Our results suggest that older siblings may influence the educational attainment of younger siblings, adding to the growing evidence that effects of the environment on phenotypic variation partially reflect social effects of germline genetic variation in relatives.
Social relations and mental ill-health among newly arrived refugees in Sweden: A cross-sectional study
Authors: Mangrio Elisabeth , Grahn Mathias , Zdravkovic Slobodan , Cuadra Carin
Published: July 2022

Background

Previous research indicates that social relations have an impact on the well-being of refugees and that well-being is important for effective integration into the host country. Few studies in Sweden have, to the best of our knowledge, looked at the association between social relations and mental ill-health among newly arrived refugees. The aim is to investigate what effect social relations have on the mental health of newly arrived refugees in the south of Sweden.

Methods

A cross-sectional study was conducted in Scania, the southernmost county of Sweden, between February 2015 and February 2016. The study population consisted of newly arrived adult refugees speaking Dari or Arabic, who received the civic and health information that is part of an introduction course for all newly arrived refugees.

Results

Individuals who rarely met with friends had higher odds of experiencing mental ill-health [OR = 1.70, 95% CI, 1.03–2.82] than individuals who frequently spent time with friends. Furthermore, individuals who seldom attended social/community meetings or activities in an organisation or group, such as a sports association or another kind of association, a church, a mosque, or women’s or men’s meetings, had higher odds of mental ill-health (OR = 1.58, 1.1–2.28), compared to those who frequently did so.

Conclusions

The study suggests a link between spending time with friends, as well as engaging in social/community activities, and the mental health of newly arrived refugees in the southernmost county of Sweden, which is one of the counties in Sweden that received the highest number of refugees. The results are in line with a previous study on the same subject in Sweden.
The role of patent waivers and compulsory licensing in facilitating access to COVID-19 vaccines: Findings from a survey among healthcare practitioners in Nigeria
Authors: Adigwe Obi Peter , Oturu Davidson
Published: July 2022

The roll out of COVID-19 vaccines has again revealed the gap between high income countries and developing nations in terms of access to healthcare commodities and services. With the slow vaccination roll out in many low income countries and the emergence of more contagious variants of COVID-19, many persons are at risk of contracting the disease in settings with low immunisation coverage. This study aimed at exploring the views of healthcare practitioners on the role of patent waivers and compulsory licensing in facilitating access to vaccines. A cross-sectional study was undertaken among practitioners in the health sector, which comprised private, public, and development agencies. A well structured and validated questionnaire was administered to the study participants using both physical and online methods of administration in Nigerian setting. A total of 526 respondents participated in the study, majority of them were males (54.4%). A third of the study participants (31.1%) had postgraduate degrees. A strong majority of the respondents (81.2%) agreed that the role of patent is to promote innovation, whilst 70.6% of them indicated that intellectual property waivers can improve access to COVID-19 vaccines. Slightly above half of the respondents (56.0%) indicated that patent waivers can reduce innovation in the pharmaceutical sector, they however indicated that such challenge can be mitigated by granting incentives to innovators whose intellectual property rights had been waived. This study has revealed that there is a need for intellectual property rights waiver and compulsory licensing of all novel COVID-19 commodities including vaccines, as this is an important strategy that can improve access to relevant products in developing countries.
Performance bonuses and the quality of primary health care delivered by family health teams in Brazil: A difference-in-differences analysis
Authors: Fardousi Nasser , Nunes da Silva Everton , Kovacs Roxanne , Borghi Josephine , Barreto Jorge O. M. , Kristensen Søren Rud , Sampaio Juliana , Shimizu Helena Eri , Gomes Luciano B. , Russo Letícia Xander , Gurgel Garibaldi D. , Powell-Jackson Timothy
Published: July 2022

Background

Pay-for-performance (P4P) programmes to incentivise health providers to improve quality of care have been widely implemented globally. Despite intuitive appeal, evidence on the effectiveness of P4P is mixed, potentially due to differences in how schemes are designed. We exploited municipality variation in the design features of Brazil’s National Programme for Improving Primary Care Access and Quality (PMAQ) to examine whether performance bonuses given to family health team workers were associated with changes in the quality of care and whether the size of bonus mattered.

Methods and findings

For this quasi-experimental study, we used a difference-in-differences approach combined with matching. We compared changes over time in the quality of care delivered by family health teams between (bonus) municipalities that chose to use some or all of the PMAQ money to provide performance-related bonuses to team workers with (nonbonus) municipalities that invested the funds using traditional input-based budgets. The primary outcome was the PMAQ score, a quality of care index on a scale of 0 to 100, based on several hundred indicators (ranging from 598 to 660) of health care delivery. We did one-to-one matching of bonus municipalities to nonbonus municipalities based on baseline demographic and economic characteristics. On the matched sample, we used ordinary least squares regression to estimate the association of any bonus and size of bonus with the prepost change over time (between November 2011 and October 2015) in the PMAQ score. We performed subgroup analyses with respect to the local area income of the family health team. The matched analytical sample comprised 2,346 municipalities (1,173 nonbonus municipalities; 1,173 bonus municipalities), containing 10,275 family health teams that participated in PMAQ from the outset. Bonus municipalities were associated with a 4.6 (95% CI: 2.7 to 6.4; p < 0.001) percentage point increase in the PMAQ score compared with nonbonus municipalities. The association with quality of care increased with the size of bonus: the largest bonus group saw an improvement of 8.2 percentage points (95% CI: 6.2 to 10.2; p < 0.001) compared with the control. The subgroup analysis showed that the observed improvement in performance was most pronounced in the poorest two-fifths of localities. The limitations of the study include the potential for bias from unmeasured time-varying confounding and the fact that the PMAQ score has not been validated as a measure of quality of care.

Conclusions

Performance bonuses to family health team workers compared with traditional input-based budgets were associated with an improvement in the quality of care.
Atypus karschi Dönitz, 1887 (Araneae: Atypidae): An Asian purse-web spider established in Pennsylvania, USA
Authors: Řezáč Milan , Tessler Steven , Heneberg Petr , Herrera Ivalú Macarena Ávila , Gloríková Nela , Forman Martin , Řezáčová Veronika , Král Jiří
Published: July 2022

The mygalomorph spiders of the family Atypidae are among the most archaic spiders. The genusAtypusLatreille, 1804 occurs in Eurasia and northern Africa, with a single enigmatic species,Atypus snetsingeriSarno, 1973, known only from a small area in southeastern Pennsylvania in eastern USA. A close relationship to European species could be assumed based on geographic proximity, butA.snetsingerimore closely resembled Asian species. This study was undertaken to learn more about the genetics ofA.snetsingeri, its habitat requirements and natural history. Molecular markers (CO1 sequences) were compared to available data for other atypids and showed thatA.snetsingeriis identical withA.karschiDönitz, 1887 native to East Asia. Natural history parameters in Pennsylvania were also similar in every respect toA.karschiin Japan, therefore, we propose that the spider is an introduced species and the specific epithetsnetsingeriis relegated to a junior synonym ofA.karschi. Cytogenetic analysis showed an X0 sex chromosome system (42 chromosomes in females, 41 in males) and we also detected nucleolus organizing regions and heterochromatin, the latter for the first time in the Atypoidea. In Pennsylvania the spider is found in a variety of habitats, from forests to suburban shrubbery, where the above-ground webs are usually attached vertically to trees, shrubs, or walls, although other webs are oriented horizontally near the ground. Prey include millipedes, snails, woodlice, carabid beetles and earthworms.Atypus karschiis the first known case of an introduced purse-web spider. It is rarely noticed but well-established within its range in southeastern Pennsylvania.
Factors motivating female sex workers to initiate pre- exposure prophylaxis for HIV prevention in Zimbabwe
Authors: Nhamo Definate , Duma Sinegugu E. , Ojewole Elizabeth B. , Chibanda Dixon , Cowan Frances M.
Published: July 2022

Background

Female sex workers (FSWs) have a 26 times greater chance of HIV infection compared to the women in the general population. The World Health Organization recommends pre-exposure prophylaxis (PrEP) for population groups with an HIV incidence of 3% or higher and FSWs in southern Africa fit this criteria. This study sought to understand factors that motivate FSWs to initiate PrEP, in Harare, Zimbabwe.

Methods

We purposively selected and recruited 20 FSWs to participate in the study in-order to gain an in-depth understanding of factors that motivate FSWs to initiate PrEP in Harare, Zimbabwe. We identified FSW who had been initiated on PrEP at a specialized clinic providing comprehensive sexual reproductive health (SRH) services for sex workers including HIV prevention options. We used a descriptive phenomenological approach to collect and analyze the data. Data was analyzed using Colaizzi’s seven steps to analyze data.

Findings

Two broad themes were identified as intrinsic and extrinsic motivators. The two broad themes each have several sub-themes. The sub-themes under intrinsic motivation were (i) Self- protection from HIV infection and (ii) condoms bursting. Six sub-themes were identified as external motivators for initiating PrEP, these included (i) occupational risk associated with sex work, (ii) increased chance of offering unprotected sex as a motivator to initiate PrEP, (iii) positive encouragement from others (iv) need to take care of the children and (v) prior participation in HIV prevention research studies and (vi) Gender Based Violence.

Conclusions

Understanding the factors that motivate FSWs to initiate PrEP is critical in developing contextually appropriate strategies to promote PrEP initiation and adherence strategies within specific and eligible populations for receiving PrEP according to the WHO guidelines (2015).
Human rights violations and associated factors of the Hijras in Bangladesh—A cross-sectional study
Authors: Amanullah A. S. M. , Abir Tanvir , Husain Taha , Lim David , Osuagwu Uchechukwu L. , Ahmed Giasuddin , Ahmed Saleh , Nur -A Yazdani Dewan Muhammad , Agho Kingsley E.
Published: July 2022

Background

Hijras in Bangladesh face considerable discrimination, stigma, and violence despite the 2013 legislation that recognized Hijras as a third gender. There is a dearth of published literature describing the extent of human rights violations among this population and their associated factors.

Methods

A questionnaire was administered to 346 study participants aged 15 years and older, living in five urban cities of Bangladesh who self-identified as Hijra, in 2019. The six human rights violation indicators (Economic, Employment, Health, Education, Social and Civic and Political Right) assessed were categorized as binary. Associations between sociodemographic characteristics and the six human rights violations were tested using univariate and multivariate logistic regression.

Results

Human right violations including economic, educational, political, employment, health and social/civil right violations were reported in 73.3%, 59.3%, 58.5%, 46.4%, 42.7%, and 34.4% of the participants, respectively. Economic rights violations were associated with bisexuality (Adjusted odds ratios [AOR] 3.60, 95%CI: 1.57, 8.26) and not living with family (AOR 2.71, 95%CI: 1.21, 6.09), while Hijras who earned more than 10,000 Bangladesh Taka experienced higher odds of educational (AOR 2.77, 95%CI: 1.06, 7.19) and political rights violations (AOR 4.30, 95%CI: 1.06, 7.44). Living in Dhaka city was associated with a reduced odds for economic and political rights violation while experiencing violations of one human right could lead to violation of another in the Hijra community.

Conclusion

Human rights violations were common in Bangladesh Hijras, particularly the Bisexual Hijras. Media and educational awareness campaigns are needed to address the underlying roots of a violation. Programs focused on the families, young people and high-income earners of this community are needed in Bangladesh.
Transfer dynamics of multi-resistance plasmids in Escherichia coli isolated from meat
Authors: Darphorn Tania S. , Koenders-van Sintanneland Belinda B. , Grootemaat Anita E. , van der Wel Nicole N. , Brul Stanley , ter Kuile Benno H.
Published: July 2022

Resistance plasmids are crucial for the transfer of antimicrobial resistance and thus form a matter of concern for veterinary and human healthcare. To study plasmid transfer, foodborne Escherichia coli isolates harboring one to five known plasmids were co-incubated with a general recipient strain. Plasmid transfer rates under standardized conditions varied by a factor of almost 106, depending on the recipient/donor strain combination. After 1 hour transconjugants never accounted for more than 3% of the total number of cells. Transconjugants were formed from 14 donors within 1 hour of co-incubation, but in the case of 3 donors 24 hours were needed. Transfer rates were also measured during longer co-incubation, between different species and during repeated back and forth transfer. Longer co-incubation resulted in the transfer of more types of resistance. Maximum growth rates of donor strains varied by a factor of 3. Donor strains often had higher growth rates than the corresponding transconjugants, which grew at the same rate as or slightly faster than the recipient. Hence, possessing one or more plasmids does not seem to burden the harboring strain metabolically. Transfer was species specific and repeated transfer of one plasmid did not result in different transfer rates over time. Transmission Electron microcopy was used to analyze the morphology of the connection between co-incubated strains. Connection by more pili between the cells resulted in better aggregate formation and corresponded with higher transfer rates.
The influence of receiving real-time visual feedback on breathing during treadmill running to exhaustion
Authors: Passafiume Joseph A. , Glover Nelson A. , Crecelius Anne R. , Chaudhari Ajit M. W.
Published: July 2022

Breathing plays a vital role in everyday life, and specifically during exercise it provides working muscles with the oxygen necessary for optimal performance. Respiratory inductance plethysmography (RIP) monitors breathing through elastic belts around the chest and abdomen, with efficient breathing defined by synchronous chest and abdomen movement. This study examined if providing runners with visual feedback through RIP could increase breathing efficiency and thereby time to exhaustion. Thirteen recreational runners (8F, 5M) ran to exhaustion on an inclined treadmill on two days, with visual feedback provided on one randomly chosen day. Phase angle was calculated as a measure of thoraco-abdominal coordination. Time to exhaustion was not significantly increased when visual feedback was provided (p = 1). Phase angle was not significantly predicted by visual feedback (p = 0.667). Six participants improved phase angle when visual feedback was provided, four of whom increased time to exhaustion. Four participants improved phase angle by 9° or more, three of whom increased time to exhaustion. Participants who improved phase angle with visual feedback highlight that improving phase angle could increase time to exhaustion. Greater familiarization with breathing techniques and visual feedback and a different paradigm to induce running fatigue are needed to support future studies of breathing in runners.
Proximal and fatty acid analysis in Ostrea chilensis, Crassostrea gigas and Mytilus chilensis (Bivalvia: Mollusca) from southern Chile
Authors: Valenzuela Andrea , Oyarzún Pablo A. , Toro Jorge E. , Navarro Jorge M. , Ramírez Oscar , Farias Ana
Published: July 2022

Oysters and blue mussels are important hydrobiological resources for aquaculture. In Chile, they are farming on the Chiloé island, where around 18% of the world’s mussels are produced, however, their nutritional dynamics are largely unknown. For this reason, the objective of this study was to determine the proximal biochemical composition and the fatty acid profile in the Chilean oyster (Ostrea chilensis), the Pacific oyster (Crassostrea gigas) and the Chilean mussel (Mytilus chilensis), to perform an intra and interspecific comparison. Shellfish sampled in winter were characterized by a high protein content, followed by medium values for lipid content and a low carbohydrate content compared to similar species in Europe. Also, oysters and mussels were found to be rich in omega-3 long chain polyunsaturated fatty acid (n-3 LC-PUFA), so they can be considered excellent functional food option for a healthy human diet. Their high contribution of n-3 LC-PUFA ranged between 5.2–12.9 μg FA mg-1 dry weight with high n-3/n-6 ratios, which depends on both the species and the on-growing location. Both taxa can be considered a plausible option to promote a healthy diet of marine origin in future generations. Also, these results could benefit the projection and development of aquaculture of these mollusks.
Impact of measured versus estimated glomerular filtration rate-based screening on living kidney donor characteristics: A study of multiple cohorts
Authors: van der Weijden Jessica , van Londen Marco , Roodnat Joke I. , Kho Marcia L. , van de Wetering Jacqueline , Kloke Heinrich , Dooper Ine M. M. , Bakker Stephan J. L. , Navis Gerjan , Nolte Ilja M. , De Borst Martin H. , Berger Stefan P.
Published: July 2022

Background

Most transplant centers in the Netherlands use estimated glomerular filtration rate (eGFR) for evaluation of potential living kidney donors. Whereas eGFR often underestimates GFR, especially in healthy donors, measured GFR (mGFR) allows more precise kidney function assessment, and therefore holds potential to increase the living donor pool. We hypothesized that mGFR-based donor screening leads to acceptance of donors with lower pre-donation eGFR than eGFR-based screening.

Methods

In this longitudinal cohort study, we compared eGFR (CKD-EPI) before donation in one center using mGFR-based screening (mGFR-cohort, n = 250) with two centers using eGFR-based screening (eGFR-cohort1, n = 466 and eGFR-cohort2, n = 160). We also compared differences in eGFR at five years after donation.

Results

Donor age was similar among the cohorts (mean±standard deviation (SD) mGFR-cohort 53±10 years, eGFR-cohort1 52±13 years, P = 0.16 vs. mGFR-cohort, and eGFR-cohort2 53±9 years, P = 0.61 vs. mGFR-cohort). Estimated GFR underestimated mGFR by 10±12 mL/min/1.73m2 (mean±SD), with more underestimation in younger donors. In the overall cohorts, mean±SD pre-donation eGFR was lower in the mGFR-cohort (91±13 mL/min/1.73m2) than in eGFR-cohort1 (93±15 mL/min/1.73m2, P<0.05) and eGFR-cohort2 (94±12 mL/min/1.73m2, P<0.05). However, these differences disappeared when focusing on more recent years, which can be explained by acceptance of more older donors with lower pre-donation eGFR over time in both eGFR-cohorts. Five years post-donation, mean±SD eGFR was similar among the centers (mGFR-cohort 62±12 mL/min/1.73m2, eGFR-cohort1 61±14 mL/min/1.73m2, eGFR-cohort2 62±11 mL/min/1.73m2, P = 0.76 and 0.95 vs. mGFR-cohort respectively). In the mGFR-cohort, 38 (22%) donors were excluded from donation due to insufficient mGFR with mean±SD mGFR of 71±9 mL/min/1.73m2.

Conclusions

Despite the known underestimation of mGFR by eGFR, we did not show that the routine use of mGFR in donor screening leads to inclusion of donors with a lower pre-donation eGFR. Therefore eGFR-based screening will be sufficient for the majority of the donors. Future studies should investigate whether there is a group (e.g. young donors with insufficient eGFR) that might benefit from confirmatory mGFR testing.