bluuebunny/crossref_metadata_2025 huggingface dataset:
Refining the E + A Galaxy: A Spatially Resolved Spectrophotometric Sample of Nearby Post-starburst Systems in SDSS-IV MaNGA (MPL-5)
Authors: Greene Olivia A. , Anderson Miguel R. , Marinelli Mariarosa , Holley-Bockelmann Kelly , Campbell Lauren E. P. , Liu Charles T.
Published: April 2021

Post-starburst galaxies are crucial to disentangling the effect of star formation and quenching on galaxy demographics. They comprise, however, a heterogeneous population of objects, described in numerous ways. To obtain a well-defined and uncontaminated sample, we take advantage of spatially resolved spectroscopy to construct an unambiguous sample of E + A galaxies—post-starburst systems with no observed ongoing star formation. Using data from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) Survey, in the fourth generation of the Sloan Digital Sky Survey (SDSS-IV), we have identified 30 E + A galaxies that lie within the green valley of color–stellar mass space. We first identified E + A candidates by their central, single-fiber spectra and (u–r) color from SDSS DR15, and then further required each galaxy to exhibit E + A properties throughout the entirety of the system to three effective radii. We describe our selection criteria in detail, note common pitfalls in E + A identification, and introduce the basic characteristics of the sample. We will use this E + A sample, which has been assembled with stringent criteria and thus re-establishes a well-defined subpopulation within the broader category of post-starburst galaxies, to study the evolution of galaxies and their stellar populations in the time just after star formation within them is fully quenched.
The Panchromatic Hubble Andromeda Treasury: Triangulum Extended Region (PHATTER). I. Ultraviolet to Infrared Photometry of 22 Million Stars in M33
Authors: Williams Benjamin F. , Durbin Meredith J. , Dalcanton Julianne J. , Lang Dustin , Girardi Leo , Smercina Adam , Dolphin Andrew , Weisz Daniel R. , Choi Yumi , Bell Eric F. , Rosolowsky Erik , Skillman Evan , Koch Eric W. , Lindberg Christina W. , Hagen Lea , Gordon Karl D. , Seth Anil , Gilbert Karoline , Guhathakurta Puragra , Lauer Tod , Bianchi Luciana
Published: April 2021

We present panchromatic resolved stellar photometry for 22 million stars in the Local Group dwarf spiral Triangulum (M33), derived from Hubble Space Telescope observations with the Advanced Camera for Surveys in the optical (F475W, F814W), and the Wide Field Camera 3 in the near-ultraviolet (F275W, F336W) and near-infrared (F110W, F160W) bands. The large, contiguous survey area covers ∼14 square kpc and extends to 3.5 kpc (14′, or 1.5–2 scale lengths) from the center of M33. The PHATTER observing strategy and photometry technique closely mimics that of Panchromatic Hubble Andromeda Treasury, but with updated photometry techniques that take full advantage of all overlapping pointings (aligned to within <5–10 milliarcseconds) and improved treatment of spatially varying point-spread functions. The photometry reaches a completeness-limited depth of F475W∼28.5 in the lowest surface density regions observed in M33 and F475W∼26.5 in the most crowded regions found near the center of M33. We find the young populations trace several relatively tight arms, while the old populations show a clear, looser two-armed structure. We present extensive analysis of the data quality, including artificial star tests to quantify completeness, photometric uncertainties, and flux biases. This stellar catalog is the largest ever produced for M33, and is publicly available for download by the community.
A DG-IMEX Method for Two-moment Neutrino Transport: Nonlinear Solvers for Neutrino–Matter Coupling*
Authors: Laiu M. Paul , Endeve Eirik , Chu Ran , Harris J. Austin , Messer O. E. Bronson
Published: April 2021

Neutrino–matter interactions play an important role in core-collapse supernova (CCSN) explosions, as they contribute to both lepton number and/or four-momentum exchange between neutrinos and matter and thus act as the agent for neutrino-driven explosions. Due to the multiscale nature of neutrino transport in CCSN simulations, an implicit treatment of neutrino–matter interactions is desired, which requires solutions of coupled nonlinear systems in each step of the time integration scheme. In this paper, we design and compare nonlinear iterative solvers for implicit systems with energy-coupling neutrino–matter interactions commonly used in CCSN simulations. Specifically, we consider electron neutrinos and antineutrinos, which interact with static matter configurations through the Bruenn 85 opacity set. The implicit systems arise from the discretization of a nonrelativistic two-moment model for neutrino transport, which employs the discontinuous Galerkin (DG) method for phase-space discretization and an implicit–explicit (IMEX) time integration scheme. In the context of this DG-IMEX scheme, we propose two approaches to formulate the nonlinear systems: a coupled approach and a nested approach. For each approach, the resulting systems are solved with Anderson-accelerated fixed-point iteration and Newton’s method. The performance of these four iterative solvers has been compared on relaxation problems with various degrees of collisionality, as well as proto–neutron star deleptonization problems with several matter profiles adopted from spherically symmetric CCSN simulations. Numerical results suggest that the nested Anderson-accelerated fixed-point solver is more efficient than other tested solvers for solving implicit nonlinear systems with energy-coupling neutrino–matter interactions.
Chromospheric Activity of Periodic Variable Stars Based on the LAMOST Low- and Medium-resolution Spectral Survey
Authors: Long Liu , Zhang Li-yun , Bi Shao-Lan , Shi Jianrong , Lu Hong-Peng , Han Xianming L. , Wang Haifeng , Prabhakar Misra
Published: April 2021

We present a catalog of 75,867 periodic variable stars from data release 7 of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope. We calculated the chromospheric activity index, equivalent widths for 201,349 spectra, and excess fractional luminosity (

R

H
α

′

) for 130,796 spectra. Based on the intensity of the Hα line, we detected 30,719 F-, G-, and K-type variable stars with Hα fill-in or emission and 2521 M-type variable stars exhibiting Hα emission. Furthermore, 14,938 out of 30,573 periodic variable stars showed Hα variability. Analysis of samples with different spectral types confirmed that the activity fraction of stars with later spectral type clearly decreases as the absolute Galactic height increases away from the Galactic plane. The results also show that at the same absolute Galactic height, the activity fractions in eclipsing binaries are higher than those in single stars. In this study, we present the activity–rotation relations for F-, G-, K-, and M-type variable stars. The results of analysis show that rapid rotators keep a saturated value, and the absolute value of the power-law index exhibits an increasing trend from F- to K-type stars in the unsaturated regime. Moreover, we confirm that the angular momentum and magnetic momentum are positively correlated, which indicates that the α–ω dynamo may be working. In addition, we confirmed the correlations among the Hα, Hβ, Hγ, Hδ, Ca ii H&K, and Ca ii infrared triplet lines.
L’avenir de la Social Security aux États-Unis
Authors: Diamond Peter A.
Published: April 2021

La Social Security américaine fait face à un risque d’insolvabilité à moyen terme. Cet article passe en revue les difficultés politiques depuis 1970 pour adopter une législation bipartisane pérenne. Il examine en particulier la réforme de 1983 qui a permis de garantir pendant près d’un demi-siècle le financement des pensions. La perspective de l’épuisement du Trust Fund en 2034 fait de nouveau resurgir le risque d’insolvabilité. L’examen de l’histoire institutionnelle récente et passée des États-Unis, ainsi que l’analyse d’expériences étrangères, permettent d’éclairer le débat actuel et de dresser un panorama des solutions possibles pour garantir l’avenir à long terme de la Social Security .
La structuration d’un domaine évaluatif transversal : retours d’expériences sur les évaluations d’impact sur la santé
Authors: Benjankhar Lamia , Cotton Paul
Published: April 2021

Depuis dix ans, l’évaluation d’impact sur la santé (EIS) connaît un développement accéléré en France. Son approche globale en santé lui confère un caractère transversal, croisant données probantes et retour d’expérience d’usagers, santé et politiques thématiques. Elle se distingue ainsi d’autres formes d’évaluations, tant sur le plan méthodologique que stratégique. Outre les défis induits par ces spécificités pour les praticiens de l’évaluation, le retour d’expérience sur cinq EIS réalisées témoigne d’une sous-exploitation de cette démarche, tant dans son potentiel opérationnel que d’ouverture de l’exercice à d’autres projets en dehors des seules opérations urbaines.
Dynamical analysis of a banking duopoly model with capital regulation and asymmetric costs
Authors: Brianzoni Serena , Campisi Giovanni
Published: April 2021

It is well known that regulation and efficiency are two important issues on banking literature. The goal of the paper is to analyse them through a banking duopoly model with heterogeneous expectations. To this purpose, we consider two scenarios. In the first one, we focus on regulation effects. In particular, empirical literature on Italian banks finds evidence on the asymmetry of the costs of regulation that penalize small banks with respect to the large ones. In this direction, we analyse a duopoly model where small banks and large banks have different forecasting rules and we capture the differences of the regulations' effects assuming asymmetry in the cost functions. We introduce linear cost function for small banks and quadratic cost function for large banks. In the second scenario, we study the relation between regulation and bank efficiency highlighting empirical results showing that large banks register higher level of inefficiency than small banks. Moreover, in order to stress new evidences and to confirm empirical results on banking regulation and efficiency, we conduct an analytical and numerical analysis.
Primer registro de la familia Cydnidae (Hemiptera: Heteroptera) en Isla de Pascua, Chile
Authors: Vargas Catalina J. , Faúndez Eduardo I. , Carvajal Mariom A.
Published: April 2021

Se presenta un nuevo registro del cídnido andino y neotropical Melanaethus spinolae (Signoret, 1863) para Chile insular. El nuevo registro proviene específicamente de Isla de Pascua, convirtiendo a esta chinche en el primer cídnido para esta isla oceánica. Se comentan las posibles causas de la expansión de este taxón.
Primera cita del elusivo calamar oceánico Thysanoteuthis rhombus Troschel, 1857 (Cephalopoda: Thysanoteuthidae) en la costa catalana
Authors: Fernández-Álvarez Fernando Ángel , Colmenero Ana I. , Barría Claudio
Published: April 2021

El chipirón volantín (Thysanoteuthis rhombus Troschel, 1857) es una especie de calamar oceánico grande y elusivo. En este trabajo se proporciona el primer registro de la especie para la costa catalana y se discute en el contexto de registros de la especie en zonas cercanas.
Investigación sobre las propiedades mecánicas y de corrosión del compuesto de matriz metálica Al 7075/Redmud.
Authors: Sambathkumar Mani , Sasikumar Kondayampalayam S.K. , Gukendran Rangasamy , Dineshkumar Karupannasamy , Ponappa Kannayiram , Harichandran Samiyappan
Published: April 2021

En el presente trabajo se realiza una investigación sobre las propiedades mecánicas y el comportamiento frente a corrosión del compuesto de matriz metálica Al 7075. El cual se preparó a partir de Al 7075 como matriz y lodo rojo como refuerzo, mediante el uso de un proceso de fundición por agitación en dos pasos. El porcentaje en volumen de refuerzo varía de 0% a 15%. La densidad del material compuesto se calculó mediante el principio de Arquímedes, mayor que la matriz básica. La distribución uniforme del refuerzo y la matriz en el material compuesto se estudió utilizando micrografías ópticas, y la microdureza del material se determinó utilizando una máquina de ensayo de dureza Vickers. La microdureza del compuesto aumentó, mientras que el refuerzo pasó del 0% al 15%. La resistencia a la tracción del material compuesto se elevó al 5% de la tolerancia de refuerzo (326 MPa), que es más alta que la matriz base. Los compuestos de matriz metálica Al 7075 presentan una velocidad de corrosión más baja en una solución de NaCl al 3,5% que la matriz base. A medida que aumenta el porcentaje en volumen en el lodo rojo, se reduce la velocidad de corrosión de los compuestos.
Efecto de la soldadura sobre la fiabilidad de las propiedades mecánicas en los materiales de acero AISI 1020 y AISI 6150
Authors: Çivi Can , İren Emre
Published: April 2021

La soldadura es uno de los métodos de fabricación y reparación más importantes de la tecnología actual. Aunque se sabe que puede reducir las propiedades mecánicas de los materiales, es una necesidad en muchas áreas y, en algunos casos, se prefiere debido a la fabricación eficiente y rápida. El uso generalizado de la soldadura ha planteado el problema de la fiabilidad de la estructura soldada. Es importante llevar a cabo análisis de confiabilidad, especialmente en construcciones soldadas críticas o algunos materiales críticos. En este estudio se seleccionaron dos materiales de acero (AISI 1020 y AISI 6150) los cuales se seleccionaron con diferentes niveles de soldabilidad. La soldadura por arco metálico con gas (GMAW), la soldadura por arco con gas tungsteno (GTAW) y la soldadura por arco metálico protegido (SMAW) se eligieron como técnicas de soldadura industrial generalizadas. Se examinaron las propiedades mecánicas soldadas y no soldadas de estos materiales teniendo en cuenta la fiabilidad y se investigó el efecto de la soldadura y los métodos de soldadura. Los análisis de confiabilidad revelaron que las propiedades mecánicas y microestructuras no predecibles son la característica principal del proceso de soldadura, especialmente en algunos materiales o métodos.
Nano plaquetas de grafeno reforzado con un compuesto fabricado mediante sinterización por inducción de alta ultra frecuencia
Authors: Çavdar Uğur
Published: April 2021

En este trabajo, se estudiaron compuestos de nanoplaquetas de grafeno (GNP) como refuerzo de una aleación de aluminio, estudiándose refuerzos con adiciones variables de hasta un 2,0% en peso de GNP. Los polvos, de diferentes composiciones, se agitaron durante 2 h a una velocidad de 35 rpm en un mezclador tipo V para obtener una dispersión homogénea. Posteriormente, se sintetizaron mediante un tratamiento térmico a 620 ºC, en un horno de inducción de ultra alta frecuencia (UHFIHS) durante 5 min y 40 MPa de presión en un entorno de vacío. Se evaluó la densidad, rugosidad superficial, pérdida de masa ocurrida durante el proceso y la dureza Vickers de los nanocomposites obtenidos en cada caso. Se realizaron análisis SEM, EDX y XRD y se examinaron los resultados obtenidos. Se evaluó el efecto de la adición de grafeno en el aluminio y se determinó que las mejores propiedades se producían para una adición de un 0,8% en peso de GNP.
Affording Twitter in Emergency Situations
Authors: Mirbabaie Milad , Amojo Ireti , Stieglitz Stefan
Published: April 2021

This study focuses on Twitter affordances and sense-making outcomes during a single emergency situation. By using an interpretive affordance lens, this study aims to assess rumors as influencers of sense-making during the 2017 Manchester terrorist attack. The authors combined a quantitative network analysis with a qualitative content analysis to assess the role of rumors during the emergency management after the attack. This study provides argumentative grounds for the notion of sense-making as a consequence of affording social media and builds on prior research to place sense-making as a cognitive process within the affordance concept. The authors emphasize new potentials to prevent or control rumors on social media for practitioners and contribute insights to rumor research. Namely, the authors contribute a novel perspective of rumors and their role during emergency management on social media.
Prefusion F–Based Polyanhydride Nanovaccine Induces Both Humoral and Cell-Mediated Immunity Resulting in Long-Lasting Protection against Respiratory Syncytial Virus
Authors: Stephens Laura M. , Ross Kathleen A. , Waldstein Kody A. , Legge Kevin L. , McLellan Jason S. , Narasimhan Balaji , Varga Steven M.
Published: April 2021

Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract infection in both young children and in older adults. Despite the morbidity, mortality, and high economic burden caused by RSV worldwide, no licensed vaccine is currently available. We have developed a novel RSV vaccine composed of a prefusion-stabilized variant of the fusion (F) protein (DS-Cav1) and a CpG oligodeoxynucleotide adjuvant encapsulated within polyanhydride nanoparticles, termed RSVNanoVax. A prime-boost intranasal administration of RSVNanoVax in BALB/c mice significantly alleviated weight loss and pulmonary dysfunction in response to an RSV challenge, with protection maintained up to at least 6 mo postvaccination. In addition, vaccinated mice exhibited rapid viral clearance in the lungs as early as 2 d after RSV infection in both inbred and outbred populations. Vaccination induced tissue-resident memory CD4 and CD8 T cells in the lungs, as well as RSV F-directed neutralizing Abs. Based on the robust immune response elicited and the high level of durable protection observed, our prefusion RSV F nanovaccine is a promising new RSV vaccine candidate.
Triangle presentations and tilting modules for SL$_{2k+1}$
Authors: Jones Corey
Published: April 2021

Triangle presentations are combinatorial structures on finite projective geometries which characterize groups acting simply transitively on the vertices of a locally finite building of type

\tilde{A}_{n-1},\ (n \ge 3)

. From a type

\tilde{A}_{n-1}

triangle presentation on a geometry of order

q

, we construct a fiber functor on the diagrammatic monoidal category

\mathrm{Web}(\mathrm{SL}^{-}_{n})

over any field

\mathbb{k}

with characteristic

p\ge n − 1

such that

q \equiv 1\ \mathrm{mod}\ p

. When

\mathbb{k}

is algebraically closed and

n

odd, this gives new fiber functors on the category of tilting modules for

\mathrm{SL}_{n}

.
Controlling the drug-resistant tuberculosis epidemic in India: challenges and implications
Authors: Husain Aliabbas A. , Kupz Andreas , Kashyap Rajpal S.
Published: April 2021

India has a higher tuberculosis (TB) burden than any other country, accounting for an estimated one-fourth of the global burden. Drug-resistant tuberculosis (DR-TB) presents a major public health problem in India. Patients with DR-TB often require profound changes in their drug regimens, which are invariably linked to poor treatment adherence and sub-optimal treatment outcomes compared to drug-sensitive TB. The challenge of addressing DR-TB is critical for India, as India contributes over 27% of global DR-TB cases. In recent decades, India has been proactive in its battle against TB, even implementing a revised National Strategic Plan to eliminate TB by 2025. However, to achieve this ambitious goal, the country will need to take a multifaceted approach with respect to its management of DR-TB. Despite concerted efforts made by the National TB Elimination Program, India faces substantial challenges with regard to DR-TB care, especially in peripheral and resource-limited endemic zones. This article describes some of the major challenges associated with mitigating the growing DR-TB epidemic in India and their implications.
Research on Influencing Factors of Sound Absorption Coefficient in Reverberation Chamber
Authors: Zhang Yue , Xie Xinxing , Mei Dongting , Shangguan Wen-Bin
Published: April 2021

In the automotive industry, testing the sound absorption coefficient of acoustic materials through reverberation chambers has been widely used. The advantage of this method is that sound waves are incident on the surface of acoustic materials randomly, which is more in line with actual engineering. At present, most of the reverberation chamber design and construction refers to the international standard ISO 354-2003. However, although the design indicators of the reverberation chamber have already met the requirements of the standard ISO 354-2003, there are still some differences between the test results of different reverberation chambers on the same group of samples to be tested, and sometimes the differences are so big they affect the engineering applications. In this paper, the sound absorption coefficients of the same group of samples in different reverberation chambers are tested, and there are some differences in the sound absorption coefficients. Also, the sound absorption coefficients of a variety of samples of different materials in several different reverberation chambers were tested, confirming that there is a phenomenon of poor repeatability of the sound absorption coefficient of the reverberation chamber test. To optimize the poor repeatability of the sound absorption coefficient of the reverberation chamber test, the diffuser in a reverberation chamber is arranged in many different ways. In each reverberation chamber with a different layout, the sound absorption coefficient of the same piece is tested. The diffuser layout of the reverberation chamber was adjusted to the optimal arrangement according to the test results of the sound absorption coefficient. Next, each factor in the testing process of the sound absorption coefficient that may have an impact on the test results is examined separately, and the influencing factors are analyzed. Finally, the optimal test scheme for testing the sound absorption coefficient in the reverberation chamber is given. More importantly, an acceptable margin of error is given regarding the sound absorption coefficient of the reverberation chamber test material.
CARB Low NOX Stage 3 Program - Final Results and Summary
Authors: Sharp Christopher , Neely Gary , Zavala Bryan , Rao Sandesh
Published: April 2021

Despite considerable progress over the last several decades, California continues to face some of the most significant air quality problems in the United States. These continued issues highlight the need for further mobile source NOX reductions to help California and other areas meet ambient air quality targets mandated by the U.S. EPA. Beginning in 2014, the California Air Resources Board (CARB) launched a program aimed at demonstrating technologies that could enable heavy-duty on-highway engines to reach tailpipe NOX levels up to 90% below the current standards, which were implemented in 2010. At the same time, mandated improvements to greenhouse gas emissions (GHG) require that these NOX reductions be achieved without sacrificing fuel consumption and increasing GHG emissions. The CARB demonstration program has progressed through several stages since it was initiated, and the Stage 3 Low NOX program completed in 2020 represents the culmination of these technology demonstration efforts. This effort, using a 2017 production diesel engine as a baseline, demonstrated a combination of technologies that enabled Low NOX emission levels near the 90% reduction target, while at the same time maintaining GHG emission rates at the same levels as the base engine.

Previous publications have gone into detail regarding individual elements of the Stage 3 technology package. This paper will present a summary of the final configuration and final results of the Stage 3 program, including results for the fully aged aftertreatment system after the equivalent of 435,000 miles of operation. The performance of the final test article will be shown over a variety of both regulatory duty cycles and other off-cycle operations. The final fuel consumption and GHG performance of the system will also be described based on the benchmarking methods specified by EPA in the Phase 2 GHG standards.
Climate Change Awareness and related Tree Planting Practices in a Rural Community in North-Western Nigeria
Authors: Gobir A.A. , Aliyu A.A. , Abubakar A.A. , Esekhaigbe C. , Joshua I.A. , Adagba K.O. , Muhammad N.S. , Omole V.N. , Ibrahim J.M. , Nmadu A.G.
Published: April 2021

Background: Tree cutting is one of the causes of climate change and a common practice in Africa, a continent under significant threat from climate change. Therefore, climate change awareness and mitigation are vital to reducing its impacts in the region. Reforestation through planting of trees is an important carbon emission reduction strategy. This study assessed climate change awareness and related tree planting practices among household heads in a Nigerian rural community.Methods: A community-based descriptive, cross-sectional study was conducted in April 2019 among all household heads in Nasarawan Buhari community. An interviewer-administered questionnaire was used to collect data from the 104 household heads (or their representatives). Data was analyzed using SPSS (version 21.0) and statistical significance was set at p value of < 0.05.Results: The mean age of respondents was 40.6±12.6 years, and most of them (87.5%) were males. Half (50.0%) were aware of climate change, and their main source of information was radio (63.5%). Most (98.1%) used fire wood for cooking. Only a minority (27.9%) planted at least a tree in the year preceding the study. There was a statistically significant association between climate change awareness and occupation (p=0.038) but not with tree planting (p=0.827).Conclusion: The results indicated that only half of respondents were aware of climate change. There was high use of wood as cooking fuel with low tree planting. Tree planting was not associated with climate change awareness. There is therefore a need for continuous climate change education and mitigation campaign in the community.
Modeling of aboveground tree stand-level biomass in Erukot Forest of Oban Division, Cross River National Park, Nigeria
Authors: Bassey S.E. , Ajayi S.
Published: April 2021

This research estimated aboveground tree stand level Biomass in Erukot Forest of Oban Division, Cross River National Park. A total of 872 individual trees were identified and measured for diameter at breast height and total height (dbh ≥ 5cm). The 872 individual trees spread across 51 species belonging to 25 different tree families. Simple random sampling was used with sampling intensity of 0.3% to lay 15 nested plots (7m x 7m, 25m x 25m and 35m x 35m). Diameter at breast height, total height and specific density of each wood species were used to determine aboveground biomass for each tree. Conversion factors were applied to estimate stand level green and dry biomass, sequestered carbon and carbon dioxide (CO2) emission in the study area. Simple linear regression models were fitted into the stand level growth data for the forest (basal area and volume). The mean diameter at breast height and mean total height were 38.5cm and 18.5m respectively. Mean basal area of 39.8 m2 ha-1 was obtained with a mean volume of 177.3 m3 ha-1 . Average green biomass, dry biomass, carbon stock and carbon-dioxide emission of 521.8113 ton ha-1 , 341.5880 ton ha-1 , 183.196 ton ha-1 and 694.2067 ton ha-1 respectively were obtained in the study area. Stand level biomass model developed for the forest showed that common logarithm of volume per hectare is significantly related to common logarithm of stand biomass (R2 = 58%). The actual and predicted biomasses were not significantly different (Paired T-test at p ˂ 0.05). Estimated bias of 0.10% for the stand biomass model means that the developed model can be used to predict the aboveground biomass of the study area without any adjustment. The research has provided easy to use regression model for determining aboveground biomass at stand level. This is very useful for carbon trade and assessment of carbon-dioxide emissions through deforestation in the study area. The model is also a tool for assessing the wood productivity of the study area and for better management of the park.

Keyword: Sequestered carbon, aboveground biomass, dry biomass, conversion factor
Factors affecting mass media methods of extension delivery system in Yakurr Local Government Area of Cross River State, Nigeria
Authors: Adie U.B. , Ayi N.A. , Eya J.E.
Published: April 2021

The study examined the factors affecting mass media methods of extension delivery system in Yakurr Local Government Area of Cross River State, Nigeria. Specially, the objectives of the study were to describe the socio-economic characteristics of the farmers, access the teaching aids available for mass media method of extension delivery, identify the extension teaching methods exposed to farmers thanmass media and to identify factors affecting mass media method of extension service delivery in the study area. A multi-stage sampling technique was used in selecting 110 respondents from five (5) council wards. Data was obtained from the farmers using a set of structured and validated questionnaires and were analyzed using descriptive statistics, chi-square and likert scale analysis. Majority (58.18%) of the farmers were male, above 50 years (44.55%), married (56.36%) and with a family size of 1-4 (43.64%).Majority (76.3%) are Christians and had obtained their First School Leaving Certificate (54.55%). The result also revealed that the individual methods, group discussions, brainstorming, lecture methods, result demonstration, method demonstration, field trip, panel discussion, seminars and workshops (representing 70%, 53.6%, 70%, 73.6%, 71.8%, 60.9%, 59.1%, 60.9%, 70% and 62.7% respectively) were the extension methods exposed to farmers in the study area. Inability to access timely up-to-date information, unavailability of broadcast facility, lack of feedback, language barriers, time barriers and difficulty in accessing information (mean values being 3.72, 3.68, 3.57, 3.55, 3.54 and 3.51 respectively) were the major factors affecting mass media methods of extension delivery system in the study area. The decision rule (chi square),revealed that four mass media, namely radio (52.510), television (52.510), print media (newspaper) (44.546) and internet (14.546) were highly accessible by the farmers but radio (52.510) and television (52.510) were more highly accessible in the study area while billboards (0.290), magazines (0.582), pamphlets (2.328) and bulletins (1.310) were not accessible by the farmers. Based on the findings, the following recommendations were made: Agricultural Extension Services, including the Ministry of  Agriculture in the state should strengthen the use of radio and television in information dissemination to farmers in the study area.

Keywords: Mass media, Extension ,Service delivery, Dissemination, Broadcast, Agriculture
Flaccid penile length and stretch factor in the newborn
Authors: Adekoya A.O. , Fetuga M.B. , Ogunlesi T.A. , Adekoya A.O. , Oba-Daini O.O. , Ajibola E.D.
Published: April 2021

Objective: Little is known about the flaccid penile length in the newborn and the degree of stretch of the penis among investigators while measuring the stretched penile length. This study aimed to document the flaccid penile length and the stretch factor in the newborn.Methods: This cross-sectional study was carried out on 200 term male infants within the first 72 hours of life. The flaccid penile length and the stretched penile length were measured with a wooden spatula and the stretch factor was calculated.Results: The mean (±SD) flaccid and stretched penile length were 30.9 ± 3.8 mm and 38.9 ± 4.0 mm respectively. The mean stretch factor was 26.4 %. Both testes had the same mean volume of 1.6 ± 0.5 ml. There was a significant correlation between flaccid and stretched penile lengths (r = 0.775, p = 0.000). The flaccid penile length was a significant predictor of the stretched penile length.Conclusion: This study has been able to determine the stretch factor while measuring the flaccid and stretch penile lengths in Nigerian newborn infants. It is recommended that the flaccid penile length be measured along with the stretched penile length and determine the stretch factor in order to compare how much investigators stretch the penis during measurement. This will allow for detailed comparison of penile anthropometry across different ethnic groups and races.

Keywords: flaccid penile length, newborn, stretch factor, stretched penile length.
Patterns of spirometry findings among patients with suspected lower airway obstruction in a tertiary hospital, South-South, Nigeria
Authors: Jumbo J. , Onini E.N. , Okoro T.E.
Published: April 2021

Objectives: The respiratory system consists of the upper airway and the lower airway. Although, the airway sub-serves several  functions, the most important functions of the airway are ventilation and gas exchange. Lower airway obstruction by diseases such as Asthma and COPD may impair airway function. Spirometry is a useful tool in the assessment of airway function. We aim to describe the observed patterns of spirometry findings among patients with suspected lower airway obstruction at the Niger Delta University Teaching Hospital (NDUTH), Okolobiri, South-South Nigeria.

Methods: Across-sectional study. Records of spirometry values were used to assess spirometry patterns. IBM SPSS software was used to analyze data.

Results: Spirometry records of a total 100 patients were analysed. Mean age was 48.90 ± 19.77 years. There were 59% males and 41% of females. Spirometry patterns were: normal-59%; obstructive-39%; restrictive-1%; mixed-1%.

Conclusion: Spirometry is a useful non-invasive tool in the diagnosis of respiratory diseases, and recommended for patient evaluation in every tertiary hospital in Nigeria.

Keywords: Spirometry pattern, airway obstruction, asthma, COPD
Research and development on climate change and greenhouse gases in support of climate-smart livestock production and a vibrant industry
Authors: Scholtz MM , Schönfeldt HC , Neser FWC , Schutte GM
Published: April 2021

Climate change represents a feedback-loop in which livestock production both contributes to the problem and suffers from the consequences. The impact of global warming and continued, uncontrolled release of greenhouse gasses (GHG) has twofold implications for the livestock industry, and consequently food security. Firstly, the continuous increase in ambient temperature is predicted to have a direct effect on the animal, as well as on food and nutrition security, due to changes associated with temperature itself, relative humidity, rainfall distribution in time and space, altered disease distribution, changes in the ecosystem and biome composition. Secondly, the responsibility of livestock production is to limit the release of greenhouse gases (GHG) or the carbon footprint, in order to ensure future sustainability. This can be done by implementing new or adapted climate-smart production systems, the use of known and new technologies to turn waste into assets, and by promoting sustainable human diets with low environmental impacts. The following elements, which are related to livestock production and climate change, are discussed in this paper: (1) restoring the value of grasslands/rangelands, (2) pastoral risk management and decision support systems, (3) improved production efficiency, (4) global warming and sustainable livestock production, (5) the disentanglement between food and nutritional needs, focusing on nutrient rich core foods, (6) GHG from livestock and carbon sequestration, and (7) water and waste management. No single organization (or industry) within South Africa can perform this research and the implementation thereof on its own. The establishment of a (virtual) centre of excellence in climate-smart livestock production and the environment for the livestock industries, with the objective to share research expertise and information, build capacity and conduct research and development studies, should be a priority.Keywords: Food and nutrition, global warming, production efficiency, rangeland, water, waste
Sustainable crossbreeding systems of beef cattle in the era of climate change
Authors: Mokolobate MC , Theunissen A , Scholtz MM , Neser FWC
Published: April 2021

Beef cattle are unique, because they not only suffer from climate change, but they also contribute to climate change through the emission of greenhouse gases (GHG). Mitigation and adaptation strategies are therefore needed. An effective way to reduce the carbon footprint from beef cattle would be to reduce the numbers and increase the production per animal, thereby improving their productivity. Sustainable crossbreeding systems can be an effective way to reduce GHG, as it has been shown to increase production. There are a wide range of different cattle breeds in South Africa which can be optimally utilized for effective and sustainable crossbreeding. This paper reports on the effects of crossbreeding on the kilogram calf weaned per Large Stock Unit (kgC/LSU) for 29 genotypes. These genotypes were formed by crossing Afrikaner (A) cows with Brahman (B), Charolais (C), Hereford (H) and Simmentaler (S) bulls and by back-crossing the F1 cows to the sire lines. A LSU is the equivalent of an ox of 450 kg with a daily weight gain of 500 g on grass pastures with a mean digestible energy (DE) content of 55% and a requirement of 75 MJ metabolizable energy (ME). Crossbreeding with A as dam line increased the kgC/LSU on average by 8 kg (+6%) - with the CA cross producing the most kgC/LSU (+8%) above that of the AA. The BA dam in crosses with C, H and S, increased kgC/LSU on average by 26 kg (+18%) above that of the AA dam, with the H x BA cross, producing the most kgC/LSU (+21%). The BA, CA, HA and SA F1 dam lines, back-crossed to the sire line breeds, increased kgC/LSU on average by 30 kg (21%), 21 kg (15%), 19kg (13%) and 26 kg (18%) above the that of the AA, respectively. The big differences between breeds in kgC/LSU provide the opportunity to facilitate effective crossbreeding that can be useful in the era of climate change. From this study it is clear that cow productivity can be increased by up to 21% through properly designed, sustainable crossbreeding systems, thereby reducing the carbon footprint of beef production.Keywords: Carbon footprint, cow productivity, kilogram calf, production systems
Methane production in different breeds, grazing different pastures or fed a total mixed ration, as measured by a Laser Methane Detector
Authors: Grobler SM , Scholtz MM , Van Rooyan H , Mpayipheli M , Neser FWC
Published: April 2021

Agriculture is responsible for 5% to 10% of the global anthropogenic greenhouse gas (GHG) emissions. Livestock contribute about 65% of agricultural GHG and enteric fermentation accounts for 90% of this. The global warming potential of CH4 is known to be 23 times more than that of carbon dioxide, resulting in it being a significant role player in the greenhouse gas family. The laser methane detector (LMD) is an instrument that has the potential to measure enteric CH4 emission from livestock under normal husbandry activities. This study was aimed at evaluating the efficiency and results, when using the LMD to measure CH4 production under normal production conditions. Twelve heifers, four each from the Bonsmara, Nguni and Jersey breeds, were subjected to grazing natural veld, forage sorghum under irrigation, oats pasture under irrigation or a total mixed ration. Measurements were taken late afternoon (18:00) when the animals were ruminating. Four repeated measurements, lasting 60 seconds each, were taken on 10 consecutive days on each of the production systems. The animals were adapted for a period of 14 days on the specific feed, before the measurements were taken. The Jersey heifers produced significantly less CH4 than the Bonsmara and Nguni on natural veld, with no significant differences between breeds on the forage sorghum. On natural veld the heifers generated 48% more CH4. These results thus indicate that the LMD produce sensible and repeatable measurements that can be interpreted in respect of CH4 production by cattle. The next step will be to increase the number of breeds, numbers per breed, and feeding strategies over all seasons in order to validate and build up a baseline data set on the use of the LMD to measure CH4 emissions from cattle under different grazing conditions.Keywords: Heifers, methane emission, pastures, total mixed ration
Visual evaluation of beef tenderness by using surface structural observations and its relationship to meat colour
Authors: Modika KY , Frylinck L , Moloto KW , Strydom PE , Heinze PH , Webb EC
Published: April 2021

The study describes the relationship between visual and instrumental measurements for colour and tenderness between five South African beef breeds: Bos indicus (Brahman), Sanga type (Nguni), British Bos taurus (Angus), European Bos taurus (Charolais) and the composite (Bonsmara). Ten animals per genotype were used (total = 50). The carcasses were split and the right sides were electrically stimulated, while the left sides were not stimulated. Steaks were aged until three days post mortem on polystyrene plates and until 9, 14 and 20 days post mortem in vacuum bags. The steaks were evaluated by visual analysis for colour, marbling, fibre separation, surface texture and structure integrity by a 10-member trained panel. Colour was also measured by the CIE L*, a*, b* system using a Minolta meter, and tenderness was measured by means of Warner-Bratzler shear force. High negative correlations were observed between the visual colour and L* (r = −0.809), b* (r = −0.698) and high positive correlations were observed between the visual colour and hue (r = 0.797). There were also negative correlations between shear force and structure integrity (r = −0.410) and fibre separation (r = −0.401). Very low negative correlations were observed between colour and shear force (r = −0.242). Therefore, although it may be possible to judge meat colour by visual analysis, it does not appear possible to predict tenderness by colour judgment. There is potential for an experienced eye to predict tenderness by observing visual structural properties such as fibre separation and structural integrity.Keywords: Meat colour and tenderness, tenderness prediction, trained visual panel, visual analysis
Effects of various concentrations of gonadotropins and 17β estradiol on the in vitro maturation of cattle oocytes selected using brilliant cresyl blue staining
Authors: Lekola K.P.M. , Ng’ambi J.W. , Nkadimeng M. , Mphaphathi M.L. , Nedambale T.L.
Published: April 2021

The objective of this study was to determine the in vitro maturation rate of cattle oocytes selected with brilliant cresyl blue (BCB) stain, in tissue culture medium 199 (TCM 199) supplemented with various concentrations of hormones. Oocytes were retrieved from abattoir-derived ovaries by aspiration. Oocytes were then exposed to 26 μM BCB stain, and classified according to the colour of their cytoplasm: BCB+ (oocytes with blue cytoplasm) and BCB- (unstained oocytes). The BCB selected and the non-selected immature oocytes were randomly allocated into TCM 199 + 10% foetal bovine serum (FBS) maturation media supplemented with three concentrations of hormones as treatments (T). The T1 group was matured in the presence of 0.5 μg follicle stimulating hormone (FSH)/mL, 5 mg luteinising hormone (LH)/mL and 2 μg estradiol (E2)/mL. The T2 group was matured in 1 μg FSH, 6 mg LH and 2.5 μg E2/mL. The T3 group was matured in 1.5 μg FSH, 7 mg LH and 4.5 μg E2/mL. The maturation rate of oocytes was determined by the protrusion of the first polar bodies 24 h after maturation. Data were analysed by ANOVA using SAS. Treatment 2 yielded higher maturation rates for with BCB+ (30.5%) and without BCB (35%) oocytes, with T1 giving a lower maturation rate for BCB+ (10.7%) and without BCB (9.7%) oocytes. However, BCB- oocytes had lower polar body extrusion (0.7%, 1% and 2.7%) for T1, T2 and T3, respectively. In conclusion, immature oocytes that were exposed to BCB+ and cultured in TCM 199 supplemented with 10% FBS, 1 μg FSH, 6 mg LH and 2.5 μg E2/mL had a higher number of matured oocytes (extrusion of first polar body), similar to those that were not exposed to BCB (no BCB). Oocyte selection with BCB staining was a useful test for classifying good-quality cattle oocytes.
Growth performance, immune status and organ morphometry in broilers fed Bacillus subtilis-supplemented diet
Authors: Sikandar A. , Zaneb H. , Younus M. , Masood S. , Aslam A. , Shah M. , Rehman H.
Published: April 2021

The present research aimed to investigate the effects of Bacillus subtilis (B. subtilis) on performance, immune system, gut, and lymphoid organs’ microarchitecture in broilers. A total of 120 day-old broiler chicks were randomly distributed into four groups. The birds were fed a corn-soy-based basal diet (BD) (control) or the same BD supplemented with 10% zinc bacitracin (ZnB), 0.05 g/kg or 0.1 g/kg of B. subtilis (BS). The broilers fed 0.1 g/kg of B. subtilis had superior mean bodyweight and lower feed conversion ratio compared with the non-supplemented or ZnB-fed groups. The BS-0.1 group registered higher antibody titer against the Newcastle disease (ND) virus. Cell-mediated immune response post Phytohaemagglutinin-P (PHA-P) injection was attained by both BS-0.1 and BS-0.05 groups. Histomorphological study revealed increased thymus cortical width, and cortex/medulla ratio in BS-0.1 group compared with control. Area of bursal follicles and germinal centres of spleen also improved in BS-0.1 group. Compared to ZnB and control, higher villus height (VH) and villus crypt ratio of the duodenum and jejunum were recorded on day 21, and higher VH of duodenum and ileum was noted on day 35 in BS-0.1 and BS-0.05 groups. In conclusion, B. subtilis-type probiotics contributed positively to better growth performance, improved immune system and modulated morphology of lymphoid organs and gut mucosa in broilers.Keywords: Immunity, intestinal mucosa, poultry, probiotics
Stock assessment of the Tigertooth croaker, Otolithes ruber (Bloch & Schneider, 1801) from the commercial prawn trawl fishery by-catch in coastal Kenya
Authors: Mzingirwa Fatuma A. , Nyamora Jane M. , Omukoto Johnstone O. , Tuda Paul
Published: April 2021

Commercial bottom prawn trawling has been reported to generate a higher proportion of by-catch of up to 70% in Kenya. The Tigertooth croaker, Otolithes ruber is one of the species caught in large quantities as commercial by-catch and also by artisanal fishers. This has led to growing concern that the species could be at risk of over-exploitation. The purpose of this study was to carry out a stock assessment of O. ruber. Stock assessment parameters were estimated using ELEFAN with the generic algorithm as included in the R package TropFishR. The length-converted catch curve and the length-based yield per recruit model were employed. The exploitation rate (F/Z = 0.71) indicates that the stock is overfished based on the length-converted catch curve. The current fishing mortality (F = 2.3) based on the catch curve is larger than the reference level ( = 1.1) based on the yield per recruit analysis and also indicates that the stock is overfished (= 2.09). To reverse the current trend of exploitation, improved management of the stock is required, which should include further studies on other by-catch species and the generation of data to capture the whole fishery for a better estimation of stock status.
ANALYSIS OF LOAD FORECASTING ACCURACY BASED ON HO CHI MINH CITY DATA
Authors: THANH NGỌC TRẦN
Published: April 2021

Short term load forecasting is one of the fundamental parts of the electric system. Among exponential smoothing methods, the Holt-Winters method is widely used to forecast the short-term load since it is easy and simple to use, and it has high ability to adapt to the forecast of different time horizons. This paper presents a new approach by combining Holt-Winters and Walk-Forward Validation methodology to forecast the maximum power demand for Ho Chi Minh City, Vietnam. The data is divided into the training and test sets in many cases. The forecast accuracy of the mean absolute error (MAE) and the mean absolute percentage error (MAPE) are used to analyze the characteristic of forecast for each day of the week.