bluuebunny/crossref_metadata_2025 huggingface dataset:
Capacity Analysis of Non-Orthogonal Multiple Access for Uplink and Downlink
Authors: Srivastava Saurabh , Dash Prajna Parimita , Kumar Sanjay
Published: February 2021

Non-orthogonal multiple access (NOMA) is intended to be used for the next generation 5G cellular networks. In this paper, the expressions for the channel capacities for symmetric and asymmetric NOMA networks have been analysed. The performance measure of user spectral efficiency and the sum-rate bounds, for the NOMA and the existing orthogonal multiple access (OMA) networks have been compared. Furthermore, analysis of user rate and capacity of NOMA network has been carried out and it is observed that the NOMA capacity region varies as a function of the power allocation factor. The corresponding models have been developed for both uplink and downlink, and simulated with MATLAB. The NOMA performance with imperfect Successive Interference Cancellation (SIC) decoding is also analysed for the downlink. It is also verified that the transmit power may be increased to counter the spectral efficiency reduction due to imperfect SIC.
Design of Dual-Band and Low-Profile SIW Cavity-Backed Slot Antenna for 5G Applications
Authors: Kumar Amit , Singh Amit Kumar
Published: February 2021

In this communication, the design of a dual-band and low-profile SIW cavity-backed slot antenna operating at K-band and Ka-band has been proposed to expand the Impedance bandwidth (IBW) of the antenna. The dual-band antenna consists of the SIW cavity with two parallel slots etched on the conductor’s ground plane. To obtain a dual-band, higher-order hybrid modes are tuned and combined to form the second band of the proposed antenna with a broader bandwidth. For dual-band antenna, fractional bandwidth of 5.26% and 6.15% are attained with the maximum gain of 5.45 dBi and 6.15 dBi at 24.7 GHz and 27.8 GHz, respectively. A cavity-backed antenna using via-hole and the slot has been proposed to improve an IBW and other antenna performance parameters. Via-hole establishes a connection between the top and bottom surfaces of the cavity, creating a new path for the current to flow by shortening the slot’s effective length. An IBW of 4.2 GHz (15.32%), where a gain of 7.8 dBi and 9.2 dBi have been realized at 25.9 GHz and 28.8 GHz, respectively. Isolation of less than 25 dB has been achieved through simulation. In terms of λ0, the overall volumetric dimension of the proposed antenna is 1.68 λ0×1.31λ0×0.04λ0. The proposed design demonstrates better performance in terms of antenna parameters, including compactness, good radiation characteristics, enhanced impedance bandwidth, and higher gain than the latest state of the art.
Active Infrastructure Sharing – A Key Enabler of Wireless Networks
Authors: Dua Tilak Raj
Published: February 2021

Innovations and dynamic technological developments motivated the era of Information and Communications. We have witnessed revolution in communication and pattern as well as in the need of connecting world. Telecom industry is always been the core of digitization. Current pandemic situation has reflected new business and connectivity models and huge dependency on the telecom sector. The telecom network enables virtual work and meetings, education, financial transaction, e commerce, health, social meetings, webinars etc. Apart from the common usage for entertainment in terms of OTT, social media – the telecom network has become fundamental to contactless transactions – telemedicine, contactless courier delivery, online shopping etc. This paper presents an overview of telecom infrastructure model, concept of infrastructure sharing and its advantages. It also discusses various factors affecting infrastructure sharing.
EUROMAIDÁN Y LA CRISIS POLÍTICA DE UCRANIA: ANTECEDENTES Y PERSPECTIVAS
Authors: KulyK Hanna
Published: February 2021

Euromaidán es el nombre dado a una serie de manifestaciones que comenzó a finales del año 2013 en Ucrania, cuando el ex presidente Victor Yanukovych declaró la suspensión de la firma del Acuerdo de Asociación con la Unión Europea. Como resultado, miles de personas salieron a las calles de Kiev para mostrar su desacuerdo con la decisión del Gobierno. De esta manera, el Euromaidán, que empezó siendo un movimiento social, acabó provocando una confrontación entre los ciudadanos y el Gobierno ucraniano, situación que derivó en un conflicto militar con Rusia en el este de Ucrania. Esta situación marcó el comienzo de la actual crisis política del país. En este artículo se presentará el contexto histórico amplio como también la cronología actual de la crisis ucraniana, desde noviembre de 2013 hasta mayo de 2019. Todos los acontecimientos de esta crisis ucraniana deben considerarse como un único proceso tal y como se muestra en la siguiente secuencia: Euromaidán, anexión de Crimea, fase activa del conflicto militar en Dombás (hasta la firma del Segundo Protocolo de Minsk en 2015), fase pasiva del conflicto militar en Dombás y militarización del Mar Negro. Finalmente, se presentarán las conclusiones y las perspectivas para el futuro.
EL DESARROLLO DE PROYECTOS MINEROS Y SU IMPACTO EN LAS COMUNIDADES DE SU ÁREA DE INFLUENCIA
Authors: Ramírez Cristina
Published: February 2021

Perú, al día de hoy, es considerado un país en vías de desarrollo, que ha encontrado en la explotación de sus recursos minerales una fuente de ingresos importante. La actividad minera y de hidrocarburos, en el 2017, ha contribuido con el 9.3% al crecimiento del Producto Bruto Interno (PBI) del país; sin embargo, el desarrollo de proyectos mineros, en todas sus etapas, sigue generando conflictos sociales dentro de las comunidades de su área de influencia directa e indirecta. Es por esta razón que el presente trabajo, a manera de estudio, se ha centrado en analizar los reajustes que ha generado el desarrollo del Proyecto Minero Constancia en las estructuras societarias de las comunidades de su área de influencia, Chilloroya y Uchuccarco. Para este fin, primero se hace una línea de tiempo con los principales conflictos sociales que se han presentado desde la firma del convenio en el 2012 hasta el 2017. Posteriormente, se realiza un análisis de los clivajes para comprender sistemáticamente las bases de las estructuras sociales del conflicto social y finalmente, a manera de conclusión, se proponen algunas recomendaciones para que el desarrollo de proyectos mineros sea más duradero y sostenible, en armonía con los pobladores de su área de influencia.
Anexo 2. Ítems informativos. Cronología informativa sobre la pandemia COVID en España (antecedentes)
Authors: Garcia Soler Guillem
Published: February 2021

Tabla resumen de la información recogida de los distintos ítems informativos en los medios escogidos.
Políticas públicas y Pueblo Mapuche: brechas y desafíos para una agenda insuficiente
Authors: Huencho Verónica Figueroa
Published: February 2021

En las últimas décadas, los pueblos indígenas han ido adquiriendo mayor notoriedad en los espacios públicos por demandas que abarcan aspectos estructurales hasta otros de carácter político y/o administrativo. En el caso de Chile, estas demandas han ido creciendo pero sin un correlato por parte del Estado, donde las decisiones se han centrado en ámbitos como la seguridad interior y la intervención de comunidades indígenas a través de diferentes acciones. Es así como el año 2019 estuvo marcado por decisiones de política pública que dejaron en evidencia, una vez más, las visiones sesgadas que existen al momento de definir e implementar estas políticas. Desde una perspectiva de política pública, y con un foco de análisis en el pueblo mapuche, este capítulo analiza los contenidos y alcances de estas medidas impulsadas en 2019 y que permiten evidenciar elementos relevantes que tensionan la relación entre el Estado y los pueblos indígenas.
Aproximaciones a la migración colombo-venezolana: Desigualdad, Prejuicio y Vulnerabilidad
Authors: Pineda G. Esther , Ávila Keymer
Published: February 2021

La situación política, económica y social de Colombia durante décadas motivó la migración de sus ciudadanos hacia el territorio venezolano, lo cual se acentuó con el conflicto armado. Venezuela, que se caracterizó desde los años 50 del siglo XX por ser un país receptor de inmigrantes, dejó de ser un destino atractivo a partir de los años 80 por la crisis económica y política que atravesó, época a partir de la cual pueden detectarse las primeras oleadas de migrantes venezolanos. Pero es a partir del año 2015 cuando se evidencia un incremento de este fenómeno como consecuencia de la profundización de la crisis política, económica y social experimentada por la sociedad venezolana y la pauperización de las condiciones de vida de gran parte de la población; esta situación ha convertido a Colombia en la opción migratoria más cercana y accesible para los venezolanos en busca de oportunidades
Los conflictos en la zona de África de los Grandes Lagos. Su impacto en el movimiento migratorio en Ruanda (1959-2017)
Authors: Dusabe Firmin
Published: February 2021

Los migrantes y los refugiados juegan un papel importante en los procesos de desarrollo y democratización, pero también en los conflictos en sus países de origen. En particular, los refugiados en el África de los Grandes Lagos han constituido uno de los principales problemas de seguridad en esta zona. En el caso de Ruanda, la Revolución de 1959 provocó una primera ola de exiliados ruandeses. Desde entonces, las luchas por el poder en el país no han parado de provocar muertes y miles de refugiados. La guerra del Frente Patriótico Ruandés (antiguos refugiados tutsis) contra el régimen de Habyarimana terminó con el genocidio de tutsis de 1994, donde millones de personas perdieron la vida y muchos miles de ruandeses se exiliaron en los países vecinos o en Europa. Tras el genocidio, el número de ruandeses que viven en el extranjero como refugiados políticos ha aumentado. Esta situación de refugiados forzosos se explica por los conflictos que ha habido en esta zona de los Grandes Lagos en estos últimos años.
Illumination characteristics of vortex beams in dark-field microscopic systems
Authors: Wang Yuqin , Yong Kangle , Tang Shanfa , Zhang Rongzhu
Published: February 2021

A Laguerre–Gaussian (LG) vortex beam is employed as an illumination source for a dark-field microscopy imaging system. To discover the influences of beam characteristics on the imaging quality, an analysis model has been established to show the light-field change rule on both object and image planes. The analytic expressions of the light field on the two planes are deduced. When a rectangular defect is simulated, the light distributions on the object and image planes with different parameters are calculated. The results show that the size of the beam spot on the object plane can be changed by adjusting the topological charge of the vortex beam to obtain the best imaging effect for defects of different scales.
Passive athermalization and achromatization of a two-component system with air gap
Authors: Ivanov Stepan E. , Romanova Galina E.
Published: February 2021

Passive athermalization allows keeping spatial resolution through the given spectral range while working within a wide temperature range without refocusing. Existing works concerning the problem of passive athermalization usually analyze two-lens components with zero thickness and air gaps. In our work, we have included an air gap into the consideration and derived general expressions for an athermal achromatic case. We have shown that including the air gap into the analysis led to the expanded area of solutions and can be considered as basic for more complex schemes. The method suggested provides the basis for designing athermal systems for various optic electronic devices.
Demonstration of a general scaling law for far-field propagation
Authors: Dolash Thomas M. , Cooper Matthew A. , Spencer Mark F. , Shakir Sami A.
Published: February 2021

This paper conducts experiments that demonstrate the utility of a
general scaling law (GSL) for far-field propagation. In practice, the
GSL accurately predicts the diffraction-limited peak irradiance in a
far-field plane, regardless of the beam shape in a near-field plane.
Within the experimental setup, we use a reflective, phase-only spatial
light modulator to generate various beam shapes from expanded and
collimated laser-source illumination, including both flattop and
Gaussian beams with obscurations, in addition to phased arrays with
these beam shapes. We then focus the resulting near-field source plane
to a far-field target plane and measure the peak target irradiance to
compare to the associated GSL prediction. Overall, the results show
excellent agreement with less than 1% error for all test cases. Such
experiments present a convenient and relatively inexpensive approach
to demonstrating laser-system architectures (of varying complexity)
that involve far-field propagation.
MONet: heterogeneous Memory over Optical Network for large-scale data center resource disaggregation
Authors: Mishra Vaibhawa , Benjamin Joshua L. , Zervas Georgios
Published: February 2021

The memory over optical network (MONet) system is a disaggregated data center architecture where serial (HMC)/parallel (DDR4) memory resources can be accessed over optically switched interconnects within and between racks. An FPGA/ASIC-based custom hardware IP (ReMAT) supports heterogeneous memory pools, accommodates optical-to-electrical conversion for remote access, performs the required serial/parallel conversion, and hosts the necessary local memory controller. An optically interconnected HMC-based (serial I/O type) memory card is accessed by a memory controller embedded in the compute card, simplifying the hardware near the memory modules. This substantially reduces overheads on latency, cost, power consumption, and space. We characterize CPU–memory performance by experimentally demonstrating the impact of distance, number of switching hops, transceivers, channel bonding, and bit rate per transceiver on the bit error rate, power consumption, additional latency, sustained remote memory bandwidth/throughput (using industry standard benchmark STREAMS), and cloud workload performance (such as operations per second, average added latency, and retired instructions per second memcached with YCSB cloud workloads). MONet pushes the CPU–memory operational limit from a few centimeters to tens of meters, yet applications can experience as low as 10% performance penalty (at 36 m) compared to a direct-attached equivalent. Using the proposed parallel topology, a system can support up to 100,000 disaggregated cards.
Coupling light to higher order transverse modes of a near-concentric optical cavity
Authors: Utama Adrian Nugraha , Chow Chang Hoong , Nguyen Chi Huan , Kurtsiefer Christian
Published: February 2021

Optical cavities in the near-concentric regime have near-degenerate transverse modes; the tight focusing transverse modes in this regime enable strong coupling with atoms. These features provide an interesting platform to explore multi-mode interaction between atoms and light. Here, we use a spatial light modulator (SLM) to shape the phase of an incoming light beam to match several Laguerre-Gaussian (LG) modes of a near-concentric optical cavity. We demonstrate coupling efficiency close to the theoretical prediction for single LG modes and well-defined combinations of them, limited mainly by imperfections in the cavity alignment.
Discrete dipole approximation method for electromagnetic scattering by particles in an absorbing host medium
Authors: Dong Jian , Zhang Wenjie , Liu Linhua
Published: February 2021

Electromagnetic (EM) scattering by particles in an absorbing host medium is frequently encountered in practical applications, which makes the conventional EM scattering theory controversial and most of the theoretical methods for EM scattering inapplicable. Most of the relevant works in literature are confined to spherical particles. In this work, we develop the discrete dipole approximation (DDA) method for EM scattering by an arbitrary particle immersed in an absorbing host medium. We elaborate how the near- and far-field scattering quantities can be calculated by DDA. The accuracy of DDA is validated by comparison with the apparent and inherent scattering quantities of spherical particles computed by exact Mie theory. Then EM extinction by non-absorbing spheroids in absorbing host medium is studied by DDA. We find that particles that are prolonged in the incident direction are more likely to produce a negative apparent extinction, which is also supported by the near-field electric field distribution. The DDA method we develop will be useful and flexible in the study of EM scattering by particles in absorbing host medium.
Coherent laser detection of the femtowatt-level frequency-shifted optical feedback based on a DFB fiber laser
Authors: Zhao Yuanyang , Zhu Desheng , Tu Yourui , Pi Lingling , Li Hongtao , Xu Lin , Hu Zhijia , Shen Yuecheng , Yu Benli , Lu Liang
Published: February 2021

The theoretical basis and experimental realization of an all-fiber self-mixing laser Doppler velocimetry based on frequency-shifted feedback in a distributed feedback (DFB) fiber laser are presented, which employs a pair of fiber-coupled acousto-optic modulators to adjust the modulation intensity and frequency of the laser self-mixing effect. Moreover, the minimum optical feedback intensity for the velocity signal successfully measured by the interferometer is 5.12 fW, corresponding to 0.16 photons per Doppler cycle. The results demonstrate that the proposed scheme can adapt to the non-contact measurement requirements of the wide-range speed and weak feedback level in the complex environment.
Role of neutrophil extracellular traps in regulation of lung cancer invasion and metastasis: Structural insights from a computational model
Authors: Lee Junho , Lee Donggu , Lawler Sean , Kim Yangjin
Published: February 2021

Lung cancer is one of the leading causes of cancer-related deaths worldwide and is characterized by hijacking immune system for active growth and aggressive metastasis. Neutrophils, which in their original form should establish immune activities to the tumor as a first line of defense, are undermined by tumor cells to promote tumor invasion in several ways. In this study, we investigate the mutual interactions between the tumor cells and the neutrophils that facilitate tumor invasion by developing a mathematical model that involves taxis-reaction-diffusion equations for the critical components in the interaction. These include the densities of tumor and neutrophils, and the concentrations of signaling molecules and structure such as neutrophil extracellular traps (NETs). We apply the mathematical model to a Boyden invasion assay used in the experiments to demonstrate that the tumor-associated neutrophils can enhance tumor cell invasion by secreting the neutrophil elastase. We show that the model can both reproduce the major experimental observation on NET-mediated cancer invasion and make several important predictions to guide future experiments with the goal of the development of new anti-tumor strategies. Moreover, using this model, we investigate the fundamental mechanism of NET-mediated invasion of cancer cells and the impact of internal and external heterogeneity on the migration patterning of tumour cells and their response to different treatment schedules.
Antipsychotics result in more weight gain in antipsychotic naive patients than in patients after antipsychotic switch and weight gain is irrespective of psychiatric diagnosis: A meta-analysis
Authors: Bak Maarten , Drukker Marjan , Cortenraad Shauna , Vandenberk Emma , Guloksuz Sinan
Published: February 2021

Introduction

Antipsychotics are associated with bodyweight gain and metabolic disturbance. Previous meta-analyses were limited to mainly antipsychotic switch studies in patients with a diagnosis of schizophrenia or psychosis with short follow-up periods. The present meta-analysis aimed to analyse the impact of weight change in antipsychotic-naive and antipsychotics switch patients and whether body weight change depended on diagnosis.

Method

We performed a meta-analysis of clinical trials of antipsychotics that reported weight change, irrespective of psychiatric diagnosis. Outcome measure was body weight change. Studies were classified into antipsychotic-naive and antipsychotic-switch. Forest plots stratified by antipsychotic and the duration of antipsychotic use were generated and results were summarised in figures.

Results

In total, 404 articles were included for the quantitative synthesis. 58 articles were on antipsychotic naive patients. In the antipsychotic naive group, all antipsychotics resulted in body weight gain. In the antipsychotic switch group, most antipsychotics likewise resulted in bodyweight gain, with exception of amisulpride, aripiprazole and ziprasidone that showed no body weight gain or even some weight loss after switching antipsychotics. Diagnosis was not a discriminating factor of antipsychotic induced weight change.

Conclusion

Antipsychotic use resulted in substantial increase in body weight in antipsychotic-naive patients. In antipsychotic-switch patients the weight gain was mild and not present in amisulpride, aripiprazole and ziprasidone. In both groups, weight gain was irrespective of the psychiatric diagnosis.
The short-term impacts of coronavirus quarantine in São Paulo: The health-economy trade-offs
Authors: Gori Maia Alexandre , Marteleto Leticia , Rodrigues Cristina Guimarães , Sereno Luiz Gustavo
Published: February 2021

We analyze the trade-offs between health and the economy during the period of social distancing in São Paulo, the state hardest hit by the COVID-19 pandemic in Brazil. We use longitudinal data with municipal-level information and check the robustness of our estimates to several sources of bias, including spatial dependence, reverse causality, and time-variant omitted variables. We use exogenous climate shocks as instruments for social distancing since people are more likely to stay home in wetter and colder periods. Our findings suggest that the health benefits of social distancing differ by levels of municipal development and may have vanished if the COVID-19 spread was not controlled in neighboring municipalities. In turn, we did not find evidence that municipalities with tougher social distancing performed worse economically. Our results also highlight that estimates that do not account for endogeneity may largely underestimate the benefits of social distancing on reducing the spread of COVID-19.
Primary and secondary supportive partnerships among HIV-positive and HIV-negative middle-aged and older gay men
Authors: Statz Matthew , Ware Deanna , Perry Nicholas , Huebner David , Cox Christopher , Brown Andre , Meanley Steven , Haberlen Sabina , Egan James , Brennan Mark , Teplin Linda A. , Bolan Robert , Friedman M. Reuel , Plankey Michael
Published: February 2021

This study describes the primary and secondary partnerships of aging gay men participating in the Understanding Patterns of Healthy Aging Among Men Who Have Sex with Men substudy of the Multicenter AIDS Cohort Study and examines differences in the prevalence of these relationship structures by HIV status while adjusting for age, education, and race/ethnicity. Relationships were compared within the following structural categories: “only a primary partnership”, “only a secondary partnership”, “both a primary and secondary relationship”, or “neither a primary nor secondary relationship”. There were 1,054 participants (51.9% HIV negative/48.1% HIV positive) included in the study. Participants had a median age of 62.0 years (interquartile range: 56.0–67.0) and most reported being non-Hispanic white (74.6%) and college educated (88.0%). Of the 1,004 participants with available partnership status data, 384 (38.2%) reported no primary or secondary partnerships, 108 (10.8%) reported secondary-only partnership, 385 (38.3%) reported primary-only partnership, and 127 (12.6%) reported both primary and secondary partnerships. Of participants who reported primary partnerships only, the prevalence rates (PRs) were lower among those 62 years and older, HIV positive, black non-Hispanic and Hispanics. Of participants who reported only having a secondary partnership, the PRs were higher among those 62 years and older and HIV positive. Of participants who did not report having either a primary or secondary partnership, the PRs were higher among those 62 years and older, HIV positive, and black non-Hispanic compared with their respective referent groups. There was no significant difference in PRs of having both primary and secondary partnerships by age category, HIV status, race/ethnicity, and education. This study aimed to fill a knowledge gap in the literature regarding both primary and secondary supportive partnerships among aging HIV-positive and HIV-negative gay men.
A DNA metabarcoding approach for recovering plankton communities from archived samples fixed in formalin
Authors: Shiozaki Takuhei , Itoh Fumihiro , Hirose Yuu , Onodera Jonaotaro , Kuwata Akira , Harada Naomi
Published: February 2021

Plankton samples have been routinely collected and preserved in formalin in many laboratories and museums for more than 100 years. Recently, attention has turned to use DNA information from formalin-fixed samples to examine changes in plankton diversity over time. However, no molecular ecological studies have evaluated the impact of formalin fixation on the genetic composition of the plankton community structure. Here, we developed a method for extracting DNA from archived formalin-preserved plankton samples to determine their community structure by a DNA metabarcoding approach. We found that a lysis solution consisting of borate-NaOH buffer (pH 11) with SDS and proteinase K effectively cleaved the cross-link formed by formalin fixation. DNA was extracted from samples preserved for decades in formalin, and the diatom community of the extracted DNA was in good agreement with the microscopy analysis. Furthermore, we stored a plankton sample for 1.5 years and demonstrated that 18S rRNA gene community structures did not change significantly from non-formalin-fixed, time-zero samples. These results indicate that our method can be used to describe the original community structure of plankton archived in formalin for years. Our approach will be useful for examining the long-term variation of plankton diversity by metabarcoding analysis of 18S rRNA gene community structure.
Evidence and magnitude of the effects of meteorological changes on SARS-CoV-2 transmission
Authors: Kaplin Adam , Junker Caesar , Kumar Anupama , Ribeiro Mary Anne , Yu Eileen , Wang Michael , Smith Ted , Rai Shesh N. , Bhatnagar Aruni
Published: February 2021

Importance

Intensity and duration of the COVID-19 pandemic, and planning required to balance concerns of saving lives and avoiding economic collapse, could depend significantly on whether SARS-CoV-2 transmission is sensitive to seasonal changes.

Objective

Hypothesis is that increasing temperature results in reduced SARS CoV-2 transmission and may help slow the increase of cases over time.

Setting

Fifty representative Northern Hemisphere countries meeting specific criteria had sufficient COVID-19 case and meteorological data for analysis.

Methods

Regression was used to find the relationship between the log of number of COVID-19 cases and temperature over time in 50 representative countries. To summarize the day-day variability, and reduce dimensionality, we selected a robust measure, Coefficient of Time (CT), for each location. The resulting regression coefficients were then used in a multivariable regression against meteorological, country-level and demographic covariates.

Results

Median minimum daily temperature showed the strongest correlation with the reciprocal of CT (which can be considered as a rate associated with doubling time) for confirmed cases (adjusted R2 = 0.610, p = 1.45E-06). A similar correlation was found using median daily dewpoint, which was highly colinear with temperature, and therefore was not used in the analysis. The correlation between minimum median temperature and the rate of increase of the log of confirmed cases was 47% and 45% greater than for cases of death and recovered cases of COVID-19, respectively. This suggests the primary influence of temperature is on SARS-CoV-2 transmission more than COVID-19 morbidity. Based on the correlation between temperature and the rate of increase in COVID-19, it can be estimated that, between the range of 30 to 100 degrees Fahrenheit, a one degree increase is associated with a 1% decrease—and a one degree decrease could be associated with a 3.7% increase—in the rate of increase of the log of daily confirmed cases. This model of the effect of decreasing temperatures can only be verified over time as the pandemic proceeds through colder months.

Conclusions

The results suggest that boreal summer months are associated with slower rates of COVID-19 transmission, consistent with the behavior of a seasonal respiratory virus. Knowledge of COVID-19 seasonality could prove useful in local planning for phased reductions social interventions and help to prepare for the timing of possible pandemic resurgence during cooler months.
Mapping major SARS-CoV-2 drug targets and assessment of druggability using computational fragment screening: Identification of an allosteric small-molecule binding site on the Nsp13 helicase
Authors: Freidel Matthew R. , Armen Roger S.
Published: February 2021

The 2019 emergence of, SARS-CoV-2 has tragically taken an immense toll on human life and far reaching impacts on society. There is a need to identify effective antivirals with diverse mechanisms of action in order to accelerate preclinical development. This study focused on five of the most established drug target proteins for direct acting small molecule antivirals: Nsp5 Main Protease, Nsp12 RNA-dependent RNA polymerase, Nsp13 Helicase, Nsp16 2’-O methyltransferase and the S2 subunit of the Spike protein. A workflow of solvent mapping and free energy calculations was used to identify and characterize favorable small-molecule binding sites for an aromatic pharmacophore (benzene). After identifying the most favorable sites, calculated ligand efficiencies were compared utilizing computational fragment screening. The most favorable sites overall were located on Nsp12 and Nsp16, whereas the most favorable sites for Nsp13 and S2 Spike had comparatively lower ligand efficiencies relative to Nsp12 and Nsp16. Utilizing fragment screening on numerous possible sites on Nsp13 helicase, we identified a favorable allosteric site on the N-terminal zinc binding domain (ZBD) that may be amenable to virtual or biophysical fragment screening efforts. Recent structural studies of the Nsp12:Nsp13 replication-transcription complex experimentally corroborates ligand binding at this site, which is revealed to be a functional Nsp8:Nsp13 protein-protein interaction site in the complex. Detailed structural analysis of Nsp13 ZBD conformations show the role of induced-fit flexibility in this ligand binding site and identify which conformational states are associated with efficient ligand binding. We hope that this map of over 200 possible small-molecule binding sites for these drug targets may be of use for ongoing discovery, design, and drug repurposing efforts. This information may be used to prioritize screening efforts or aid in the process of deciphering how a screening hit may bind to a specific target protein.
Age-related changes in the neuromuscular control of forward and backward locomotion
Authors: Dewolf Arthur H. , Sylos-Labini Francesca , Cappellini Germana , Ivanenko Yury , Lacquaniti Francesco
Published: February 2021

Previous studies found significant modification in spatiotemporal parameters of backward walking in healthy older adults, but the age-related changes in the neuromuscular control have been considered to a lesser extent. The present study compared the intersegmental coordination, muscle activity and corresponding modifications of spinal montoneuronal output during both forward and backward walking in young and older adults. Ten older and ten young adults walked forward and backward on a treadmill at different speeds. Gait kinematics and EMG activity of 14 unilateral lower-limb muscles were recorded. As compared to young adults, the older ones used shorter steps, a more in-phase shank and foot motion, and the activity profiles of muscles innervated from the sacral segments were significantly wider in each walking condition. These findings highlight age-related changes in the neuromuscular control of both forward and backward walking. A striking feature of backward walking was the differential organization of the spinal output as compared to forward gait. In addition, the resulting spatiotemporal map patterns also characterized age-related changes of gait. Finally, modifications of the intersegmental coordination with aging were greater during backward walking. On the whole, the assessment of backward walk in addition to routine forward walk may help identifying or unmasking neuromuscular adjustments of gait to aging.
Key factors influencing earthquake-induced liquefaction and their direct and mediation effects
Authors: Hu Jilei , Tan Yunzhi , Zou Wenjun
Published: February 2021

Many factors impact earthquake-induced liquefaction, and there are complex interactions between them. Therefore, rationally identifying the key factors and clarifying their direct and indirect effects on liquefaction help to reduce the complexity of the predictive model and improve its predictive performance. This information can also help researchers understand the liquefaction phenomenon more clearly. In this paper, based on a shear wave velocity (Vs) database, 12 key factors are quantitatively identified using a correlation analysis and the maximum information coefficient (MIC) method. Subsequently, the regression method combined with the MIC method is used to construct a multiple causal path model without any assumptions based on the key factors for clarifying their direct and mediation effects on liquefaction. The results show that earthquake parameters produce more important influences on the occurrence of liquefaction than soil properties and site conditions, whereas deposit type, soil type, and deposit age produce relatively small impacts on liquefaction. In the multiple causal path model, the influence path of each factor on liquefaction becomes very clear. Among the key factors, in addition to the duration of the earthquake and Vs, other factors possess multiple mediation paths that affect liquefaction; the thickness of the critical layer and thickness of the unsaturated zone between the groundwater table and capping layer are two indirect-only mediators, and the fines content and thickness of the impermeable capping layer induce suppressive effects on liquefaction. In addition, the constructed causal model can provide a logistic regression model and a structure of the Bayesian network for predicting liquefaction. Five-fold cross-validation is used to compare and verify their predictive performances.
A new reproductive mode in anurans: Natural history of Bokermannohyla astartea (Anura: Hylidae) with the description of its tadpole and vocal repertoire
Authors: Malagoli Leo Ramos , Pezzuti Tiago Leite , Bang Davi Lee , Faivovich Julián , Lyra Mariana Lúcio , Giovanelli João Gabriel Ribeiro , Garcia Paulo Christiano de Anchietta , Sawaya Ricardo Jannini , Haddad Célio Fernando Baptista
Published: February 2021

Anurans have the greatest diversity of reproductive modes among tetrapod vertebrates, with at least 41 being currently recognized. We describe a new reproductive mode for anurans, as exhibited by the Paranapiacaba Treefrog, Bokermannohyla astartea, an endemic and poorly known species of the Brazilian Atlantic Forest belonging to the B. circumdata group. We also describe other aspects of its reproductive biology, that are relevant to understanding the new reproductive mode, such as courtship behavior, spawning, and tadpoles. Additionally, we redescribe its advertisement call and extend its vocal repertoire by describing three additional call types: courtship, amplectant, and presumed territorial. The new reproductive mode exhibited by B. astartea consists of: (1) deposition of aquatic eggs in leaf-tanks of terrestrial or epiphytic bromeliads located on or over the banks of temporary or permanent streams; (2) exotrophic tadpoles remain in the leaf-tanks during initial stages of development (until Gosner stage 26), after which they presumably jump or are transported to streams after heavy rains that flood their bromeliad tanks; and (3) tadpole development completes in streams. The tadpoles of B. astartea are similar to those of other species of the B. circumdata group, although with differences in the spiracle, eyes, and oral disc. The vocal repertoire of B. astartea exhibits previously unreported acoustic complexity for the genus. Bokermannohyla astartea is the only bromeligenous species known to date among the 187 known species within the tribe Cophomantini. We further discuss evolutionary hypotheses for the origin of this novel reproductive mode.
Higher levels of autistic traits associated with lower levels of self-efficacy and wellbeing for performing arts professionals
Authors: Buckley Eleanor , Pellicano Elizabeth , Remington Anna
Published: February 2021

This study sought for the first time to identify the extent to which autistic people are pursuing careers in the performing arts, and to determine the nature of the relationship between individuals’ autistic traits and their reported wellbeing. To address these aims, we recruited a self-selecting, community-based sample of individuals working in the performing arts and invited them to complete an online survey. A total of 1,427 respondents took part. We collected responses on participants’ backgrounds, including diagnostic history as well as measures assessing their level of autistic traits, perceived occupational self-efficacy, quality of life, and mental health. They were also asked open-ended questions about support needed, received, or desired in their workplace. Eleven of the 1,427 professionals (1%) reported a clinical diagnosis of autism. Correlational analyses demonstrated that higher levels of autistic traits were significantly associated with lower levels of quality of life, lower levels of occupational self-efficacy and greater severity of mental health conditions. Almost half the sample of professionals (N = 621; 44%) reported a desire for more employment-based support, and autistic traits were significantly higher in those participants who wanted greater support. Within the community of those working in the performing arts, there are a minority of individuals who are autistic or who have high levels of autistic traits. We have demonstrated for the first time that these individuals may be especially vulnerable to lower wellbeing.
A scaling approach to estimate the age-dependent COVID-19 infection fatality ratio from incomplete data
Authors: Seoane Beatriz
Published: February 2021

SARS-CoV-2 has disrupted the life of billions of people around the world since the first outbreak was officially declared in China at the beginning of 2020. Yet, important questions such as how deadly it is or its degree of spread within different countries remain unanswered. In this work, we exploit the ‘universal’ increase of the mortality rate with age observed in different countries since the beginning of their respective outbreaks, combined with the results of the antibody prevalence tests in the population of Spain, to unveil both unknowns. We test these results with an analogous antibody rate survey in the canton of Geneva, Switzerland, showing a good agreement. We also argue that the official number of deaths over 70 years old might be importantly underestimated in most of the countries, and we use the comparison between the official records with the number of deaths mentioning COVID-19 in the death certificates to quantify by how much. Using this information, we estimate the infection fatality ratio (IFR) for the different age segments and the fraction of the population infected in different countries assuming a uniform exposure to the virus in all age segments. We also give estimations for the non-uniform IFR using the sero-epidemiological results of Spain, showing a very similar increase of the fatality ratio with age. Only for Spain, we estimate the probability (if infected) of being identified as a case, being hospitalized or admitted in the intensive care units as function of age. In general, we observe a nearly exponential increase of the fatality ratio with age, which anticipates large differences in total IFR in countries with different demographic distributions, with numbers that range from 1.82% in Italy, to 0.62% in China or even 0.14% in middle Africa.
Understanding the sustainability debate on forest biomass for energy in Europe: A discourse analysis
Authors: Mather-Gratton Zachary James , Larsen Søren , Bentsen Niclas Scott
Published: February 2021

The legislative process before the adoption of the revised European Union renewable energy directive mobilised various actors around the forest biomass issue in Europe. Which storylines do actors use to discuss and define the sustainability of forest biomass, how are the differences between the existing storylines explained, and can distinct ‘discourse coalitions’ of actors be observed as following each storyline? These questions are addressed through a discourse analysis to critically evaluate the debate around the utilisation of forest biomass for European renewable energy to identify persistent storylines adopted by discourse coalitions as they communicate their understanding of the issue, and compete to influence the policymaking and public perception. The hypotheses are that there are more than the hypothetical binary arrangement of pro versus anti storylines, and that some actors follow multiple storylines. Locating the methodological approach on the two dimensions; text versus context and critical versus constructivist, this study pays closer attention to context rather than on individual linguistic elements of texts. Regarding the second dimension, this study builds upon constructivist epistemology, being concerned with understanding which truths these storylines produce for their speakers, and their external influences upon alternative storylines and actors. The three storylines presented here represent three competing discourses regarding forest biomass usage in European renewable energy: forestry prioritised, climate focussed and critical. Each of these are promoted by actors aiming to gain discursive hegemony on the issue, both in terms of the impact of their discourse upon EU policy making and in the eyes of the public. Despite the discursive differences created by these deeply held opposing views of what sustainability and nature are and what this means for forest biomass, there were several points where narrative elements overlapped. These can provide insight for developing a more constructive debate on the sustainability of forest biomass.
Effects of phosphorus deficiency on the absorption of mineral nutrients, photosynthetic system performance and antioxidant metabolism in Citrus grandis
Authors: Meng Xin , Chen Wei-Wei , Wang Yan-Yu , Huang Zeng-Rong , Ye Xin , Chen Li-Song , Yang Lin-Tong
Published: February 2021

Phosphorus (P) is an essential macronutrient for plant growth, development and production. However, little is known about the effects of P deficiency on nutrient absorption, photosynthetic apparatus performance and antioxidant metabolism in citrus. Seedlings of ‘sour pummelo’ (Citrus grandis) were irrigated with a nutrient solution containing 0.2 mM (Control) or 0 mM (P deficiency) KH2PO4 until saturated every other day for 16 weeks. P deficiency significantly decreased the dry weight (DW) of leaves and stems, and increased the root/shoot ratio in C. grandis but did not affect the DW of roots. The decreased DW of leaves and stems might be induced by the decreased chlorophyll (Chl) contents and CO2 assimilation in P deficient seedlings. P deficiency heterogeneously affected the nutrient contents of leaves, stems and roots. The analysis of Chl a fluorescence transients showed that P deficiency impaired electron transport from the donor side of photosystem II (PSII) to the end acceptor side of PSI, which showed a greater impact on the performance of the donor side of PSII than that of the acceptor side of PSII and photosystem I (PSI). P deficiency increased the contents of ascorbate (ASC), H2O2 and malondialdehyde (MDA) as well as the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR) and glutathione reductase (GR) in leaves. In contrast, P deficiency increased the ASC content, reduced the glutathione (GSH) content and the activities of SOD, CAT, APX and monodehydroascorbate reductase (MDHAR), but did not increase H2O2 production, anthocyanins and MDA content in roots. Taking these results together, we conclude that P deficiency affects nutrient absorption and lowers photosynthetic performance, leading to ROS production, which might be a crucial cause of the inhibited growth of C. grandis.
Is a Refundable Deductible Insurance an advantage for the insured? a mathematical approach
Authors: Claramunt M. Mercè , Mármol Maite
Published: February 2021

Most insurance policies include a deductible, so that a part of the claim is paid by the insured. In order to get full coverage of the claim, the insured has two options: purchase a Zero Deductible Insurance Policy or purchase an insurance policy with deductible together with Refundable Deductible Insurance. The objective of this paper is to analyze these two options and compare the premium paid by each. We definedif(P) as the difference between the premiums paid. This function depends on the parameters of the deductible applied, and we focus our attention on the sign of this difference and the calculation of the optimal deductible, that is, the values of the parameters of the deductible that allow us to obtain the greatest reduction in the premium.
Serum symmetric dimethylarginine shows a relatively consistent long-term concentration in healthy dogs with a significant effect of increased body fat percentage
Authors: Hillaert Amber , Liu Daisy J. X. , Daminet Sylvie , Broeckx Bart J. G. , Stock Emmelie , Paepe Dominique , Hesta Myriam , Vanderperren Katrien
Published: February 2021

Symmetric dimethylarginine (SDMA) is a promising renal marker that correlates well with the glomerular filtration rate and could allow earlier detection of impaired renal function. The main objectives of this study were to assess the long-term variability of SDMA in healthy dogs and examine the influence of an increased body fat percentage on the level of SDMA. Sixteen lean Beagles were randomly assigned to the control group or weight-change group in age- and gender-matched pairs. The energy intake of the control group (n = 8) was strictly regulated to maintain an ideal body weight for 83 weeks, while the weight-change group (n = 8) was fed to induce weight gain (week 0–47), to maintain stable excessive body weight (week 47–56) and to lose weight (week 56–83), consecutively. At 8 specified time points, the body condition score, body composition, glomerular filtration rate, serum concentration of SDMA and creatinine were analyzed. In the control group, the within-subject coefficient of variation, between-subject coefficient of variation, reference change value (type I error = 5%) and index of individuality were 0.16, 0.22, 0.43 and 0.73, respectively. The control group and weight-change group did not differ significantly in SDMA concentration. SDMA showed a significant negative association (coefficient = -0.07) with body fat percentage (p<0.01) in the weight-change group and a significant positive association (coefficient = 7.79) with serum creatinine (p<0.01) in the entire study population. In conclusion, SDMA concentration has high long-term stability in healthy adult dogs. For the evaluation of SDMA concentrations, subject-specific reference values are preferred over a population-based reference value seen their higher sensitivity. Moreover, an increased body fat percentage does seem to affect the serum SDMA concentration of otherwise healthy dogs, but its clinical relevance has to be clarified in further research.