bluuebunny/crossref_metadata_2025 huggingface dataset:
Control de existencias y su relación con la gestión rentable en una distribuidora de alimentos
Authors: Lima Amado Debbie Alissa
Published: April 2024

La presente investigación analiza la relación entre el control de existencias y la gestión rentable de una distribuidora de alimentos, en Arequipa, en el año 2023. En cuanto a la metodología, el estudio fue de tipo cuantitativo y aplicado, con un nivel correlacional de carácter transversal. La población estuvo conformada por 50 individuos que laboraban en la entidad, a quienes se les aplicó un cuestionario para reunir información sobre la aplicación del control de existencias y la gestión rentable; dicho instrumento fue validado mediante el juicio de expertos y se determinó su confiabilidad con base en el alfa de Cronbach. En los resultados se halló que la relación entre las variables es alta y significativa, por ende, se aceptó la hipótesis de investigación, dado que se observó un valor de Rho de Spearman de 0,989 y un grado de significancia de 0,000; de manera adicional, se visualizó un valor de coeficiente de Spearman mayor a 0,9 y una significancia de 0,000; ello nos demuestra el vínculo fuerte y significativo entre la rentabilidad económica, financiera y comercial. Para concluir, la investigación culmina con la confirmación de la relevancia de un eficiente control de existencias para optimizar la gestión rentable en una distribuidora de alimentos, además, adoptar dichas acciones traerá consigo un almacenamiento correcto de existencias y mayor ganancia.
Estrategias de marketing competitivo para mejorar el posicionamiento del local “H Sports Bar” de Bahía de Caráquez
Authors: Lemoine Quintero Frank Angel , Proaño Delgado Noelia Thaily
Published: April 2024

El marketing competitivo se ha convertido en la herramienta más efectiva para alcanzar mejor cuota de mercado a nivel regional. El objetivo del estudio fue analizar la efectividad de estrategia de marketing competitivo para mejorar el posicionamiento del local H Sports Bar de Bahía de Caráquez. Bajo el contexto cuantitativo se aplicó el método descriptivo para desarrollar un estudio que describa los hechos basados en los instrumentos aplicados. Entre los resultados más relevantes refirieron tener en cuenta a los bares como fuente de entretenimiento, lo que se deja entrever con la objetividad con la que se califica a los bares, con base en esto se pueden plantear varias estrategias para poder fortalecer la imagen y lograr fidelizar a clientes potenciales. Entre los puntos fuertes de H Sports Bar se destacan el mercado, la fidelización y la segmentación del mercado, por lo que se hace una comparación con otro local para ver cuáles son los puntos fuertes de cada uno y así mejorar el local. Por lo tanto, la propuesta se orientó en la elaboración de una página web para fortalecer el posicionamiento competitivo del local H Sports Bar de Bahía de Caráquez.
Validation of an enzyme-linked immunosorbent assay test-system for bevacizumab concentration determing in biological fluids
Authors: Pisarev V. V. , Ivanov A. V.
Published: April 2024

Introduction. One of the reasons for the development of many diseases primarily malignant is the increased expression of Vascular Endothelial Growth Factor (VEGF). Bevacizumab is a drug that neutralizes the biological activity of VEGF. The molecular structure of bevacizumab is a recombinant humanized antibody. Its use reduces vascularization in the foci of increased VEGF expression which slows down tumor growth and also helps restore vision in a number of ophthalmic diseases. To determine the concentration of bevacizumab in human biological fluids a test system based on Enzyme-linked Immunosorbent Assay (ELISA) is presented.

Aim. Aim of this study is the validation of this test system.

Materials and methods. Blank sera of volunteers, bevacizumab solution, enzyme-linked immunosorbent assay, solid-phase sandwich ELISA kit, microplate photometer.

Results and discussion. The following characteristics of the test system were determined: the lower limit of quantification is 2.0 mcg/ml, the upper calibration range is up to 200 mcg/ml, the accuracy and precision within one series and between series does not exceed 20 %, and the total error of the method – 30 %, short-term stability for samples at room temperature – 6 hours, long-term stability – 14 days at –20 °C, the ability to freeze/thaw of samples is up to three times, the ability to determine samples with a concentration above the upper calibrator after diluting in 2 times.

Conclusion. The results obtained fully comply with international acceptance criteria and allow the use of the ELISA test system manufactured by LLC "Probiotek" for use in the field of clinical laboratory diagnostics.
Preservative-Free Fixed Combination of Tafluprost 0.0015% and Timolol 0.5% for Treatment-Naive Patients with Open-Angle Glaucoma
Authors: Rhee Teakkwan , Kim Jaeheon , Ha Ahnul
Published: April 2024

Purpose: To assess efficacy, safety, and tolerability of the preservative-free (PF) fixed-dose combination (FC) of tafluprost 0.0015%/timolol 0.5% (PF tafluprost/timolol FC) in treatments-naive patients with primary open-angle glaucoma (POAG).Methods: This was a retrospective, real-world clinical practice setting study that included 107 eyes of 107 subjects with POAG who had never been treated for glaucoma. All subjects were received PF tafluprost/timolol FC once daily. Intraocular pressure (IOP) levels were documented for each eye at the untreated baseline and up to 6 months after the initiation of medical treatment. All adverse events, including ocular and systemic adverse reactions, were recorded. Additionally, the reasons for medication discontinuations were thoroughly documented.Results: A total of 32 POAG patients with high-baseline IOP (>21 mmHg) and 75 with normal-baseline IOP were included in the study. The subjects’ baseline mean age was 62.4 ± 8.7 years (range, 26.0–85.0 years); among them, 42 were female (39.3%). Mean IOP at baseline for all patients was 18.6 ± 4.3 mmHg. The mean IOP at 6 months was 12.6 ± 4.7 mmHg, representing a significant decrease compared to the baseline (–32%, p < 0.001). In POAG patients with high-baseline IOP, mean IOP was significantly lowered from 28.0 ± 5.7 mmHg at baseline to 18.0 ± 5.5 mmHg (–35%, p < 0.001); in patients with normal-baseline IOP, from 14.6 ± 3.4 mmHg at baseline to 10.3 ± 4.1 mmHg (–29%, p < 0.001). PF tafluprost/timolol FC was well-tolerated and safe. After 6 months, 97.2% of all patients remained on therapy.Conclusions: In this real-world observational study, once-daily treatment with PF tafluprost/timolol FC demonstrated clinically relevant and statistically significant efficacy, as well as safety and good tolerability, in treatment-naive patients diagnosed with POAG.
Unique Carbon Fibers for High-Temperature Applications
Authors: Yancey Robert , Haulik Tom , Fricano John , Chang Gary , Dust Adam , Burton Charles , Garnier John
Published: April 2024

Carbon-carbon composites have been used for many decades in applications, such as rocket nozzles, brakes, and thermal protection systems (TPS). The material consists of carbon fiber in a matrix of carbon/graphite. Carbon-carbon provides structural performance while withstanding extremely high temperatures. The material has a low coefficient of thermal expansion and performs well under thermal shock. Interest in carbon-carbon has grown recently with the focus on hypersonic weapon systems that undergo high thermal shock. The challenge with hypersonics is to develop a thermal protection systems that does not ablate or erode so the control surfaces of a hypersonic weapon remain intact to allow for manuevering of the weapon in flight. Most carbon-carbon composites produced to date do ablate at elevated temperatures and there continues to be many applications for this material. Rocket nozzles and throats are a primary example and with the increases in launches of rockets, ablative carbon-carbon will still be key component in launch systems.
Upgraded VKI Plasmatron capabilities with supersonic nozzles for extended material characterization methods
Authors: ElRassi J. , Holum S. , Sombaert L. , Viladegut A. , Walpot L. , Chazot O. , Helber B.
Published: April 2024

In the domain of re-entry and hypersonic vehicles, advancing material development requires comprehensive material testing to thoroughly understand the aero-thermo-chemistry at the surface. This paper overviews hypersonic, high-temperature activities conducted at the von Karman Institute for Fluid Dynamics (VKI) Plasmatron facility, employing three recently developed supersonic nozzles. These activities aim to augment VKI’s experimental and numerical capabilities in high-temperature material research, contributing to a deeper understanding of the chemical surface interactions, at stagnation and off-stagnation locations, during re-entry. The newly developed nozzles were 3D printed using an additive manufacturing aluminum alloy. The three nozzles serve distinct purposes: two conical ones of varying lengths are designed for stagnation point testing, while the third nozzle, adopting a semi-elliptical shape, is tailored for off-stagnation point testing. The initial section of the paper focuses on designing, manufacturing, and simulating these nozzles, then we characterize the nozzle flow and compare with simulations, while the subsequent part will delve into showcases of recent activities conducted in the Plasmatron facility utilizing these distinct nozzle configurations.
Homogenization Model for Multistable Honeycomb Metastructures with Beam-like Behavior
Authors: Boston D. Matthew , Arrieta Andres F.
Published: April 2024

Reduced order models facilitate initial design space investigations and enable assessing the benefits of compliant structures utilized for shape adaptability. This work presents a simple model to determine the flexural rigidity of a beam-like, multistable metastructure used as a spar in a hybrid spanwise morphing wing. The model considers the more complex metabeam as a homogeneous beam described by Euler-Bernoulli beam theory with an equivalent flexural rigidity. The analytical model's validity is established by comparing the obtained static and dynamic responses to finite element simulations. A closed-form expression of the flexural rigidity is then given, drawing from the multistable honeycomb's material properties and the metabeam’s geometry. The model's limitations are addressed by examining several specific cases of the metabeam’s morphed configurations and a more complex metabeam structure.
A MACHINE LEARNING-BASED ACCELERATED PYROLYSIS CHARACTERIZATION AND OPTIMIZATION OF HIGH-TEMPERATURE COMPOSITES
Authors: Picazo Paulina Portales , Cheng Roger , Gray Alexander , Zobeiry Navid
Published: April 2024

Manufacturing polymer-based composites for high-temperature applications involves a series of complex steps during which the material undergoes several transformations. These typically include a lay-up step, a curing process, a high-temperature pyrolytic process to convert the resin phase into amorphous carbon, followed by several resin backfill steps, and finally, graphitization to achieve the desired crystalline structure of carbon atoms. The parameters used during the pyrolysis process significantly affect the degradation reactions, the final yield, laminate permeability, and hence the final properties of the material. Typically, extensive testing is required to characterize pyrolysis kinetics and identify optimal processing conditions. This paper addresses these challenges through a novel probabilistic machine-learning (ML)-based approach for the accelerated characterization and optimization of the pyrolysis process, utilizing theory-based transformations of limited experimental data affected by noise and errors. Gaussian Process Regression (GPR), a Bayesian probabilistic approach to regression, is used to determine optimal test parameters to accurately characterize pyrolysis kinetics and achieve the desired yield while satisfying specific constraints. This approach can be used to improve the processing efficiency of high-temperature composites and increase their performance with minimal experimental effort.
A Bayesian Generalized Regression Approach for estimating parameters in the Item Sum Technique of sensitive surveys
Authors: Alakija T. O. , Adeleke I. A. , Adamu M. O. , Adekeye K. S.
Published: April 2024

Most respondents find it difficult to respond to sensitive questions in surveys especially providing information that require one to disclose behaviors that are possibly against social norms. This study involves solving the problem of non-response or falsification of information in a sample survey as a result of sensitive questions using the Item Sum Technique (IST). The IST is a recent indirect method for collecting data for continuous sensitive characteristics and it is a quantitative variant of the Item Count Technique (ICT). The calibration method has previously been used to estimate the IST, but the method is design-based and only useful for sufficiently large domains. There are situations where the domain sample size is not adequate to meet the needs of the precision of the estimates, hence the smallarea estimation which is model-based may be needed. The Bayesian method is a model-based estimation method that tackles the problem of small area sample size. Results from simulation indicate the efficiency of the Bayesian Generalized Regression (BGREG) method for both small and large domain samples as compared with the Generalized Regression (GREG) and calibration method using three different criteria, AIC, BIC and MSE. A small sample survey on the use of substance abuse and internet gambling among university students from Nigeria was further used to show that the BGREG outperformed the GREG and Calibration methods using the AIC, BIC and MSE criterion.
Hepatoprotective and nephroprotective property of Zingiber officinale leaves in acetaminophen induced liver and kidney damage in Wistar rats
Authors: Ibukun O , Ibukun O
Published: April 2024

It is necessary to search for safe compounds for management of kidney and liver diseases, due to sideeffects of currently available drugs. This research studied the hepatoprotective and nephroprotective effects of Zingiber officiale leaves in Wistar rats using acetaminophen as toxicant. Thirty rats were classified to five categories comprising of six animals each. The first group was the normal control and was given only vehicle (distilled water). Groups 2 served as acetaminophen control and was givenacetaminophen (750mg/kg). Groups 3, 4, 5 received acetaminophen (750mg/kg). Groups 3, 4, 5 also received silymarin (reference drug; 50mg/kg), Zingiber officiale (200mg/kg), Zingiber officiale (400mg/kg) respectively. All administration was done by oral means for 21 days. Experimental rats were thereafter euthanized by cervical dislocation. Blood and other tissues were harvested. Results showed that rats in normal control, silymarin and Zingiber officinale groups had significantly (p < 0.05)lower serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), bilirubin, urea and creatinine levels in comparison with  rats in acetaminophen control. Rats in acetaminophen  control had lower concentration of protein in serum, in comparison with normal control, silymarin or Zingiber officiale treated groups. Furthermore, reduced glutathioneconcentration was lowered and malondialdehyde concentration was raised in tissues (liver and kidney) in acetaminophen control rats in comparison with other groups. There was no significant difference in the ALP, AST, total protein, albumin, bilirubin, urea, creatinine, GSH and MDA levels of treatment groups (3, 4 and 5). These findings imply that methanol leaf extract of Zingiber officiale possess hepatoprotective, nephroprotective and antioxidant effects in rats. The study is therefore relevantin the discovery of new compounds for ameliorating the burden of liver and kidney diseases.
Implementation of a Wide Band and Low Noise Signal Generator Based on Phase Locked Loop
Authors: Mutinda M. B. , Munji K. M. , Nyenge L. R.
Published: April 2024

A signal generator, an essential electronic test instrument with versatile applications, finds its utility in various fields such as cellular communications, radar systems, microstrip antennas, and electronics labs. This research focuses on the simulation and design of a low-phase noise signal generatoroperating in frequency range of 35 MHz to 3 GHz . To accomplish this, an Atmega 328P microcontroller on an Arduino board was employed to control the synthesizer based on the Phase-Locked-Loop (PLL) concept. The signal generator’s performance was assessed, with particular emphasis on predicting and analyzing the phase noise generated by the PLL components. To ensure a robust system, a third-order loop filter was devised to effectively suppress spurs. Through simulation using the ADIsimPLLsimulation tool, optimal values for loop bandwidth (10 kHz) and phase margin (45°) were obtained. The chosen Phase-Locked-Loop chip for this implementation was the ADF4351, manufactured by Analog Devices. By conducting transient analysis, the time required for the PLL system to transition from the minimum to the maximum output frequency was determined. Furthermore, the characteristics of the generator’s signal were investigated in the frequency range of 35-100 MHz using a cathode ray oscilloscope, and for 101-3000 MHz using a spectrum analyzer. The phase noise levels were calculated at different frequencies (35 MHz, 387 MHz, 1 GHz, 2 GHz, and 2.9 GHz) and analyzed at varying offsets (1 kHz, 10 kHz,100 kHz, and 1 MHz). Comparatively, the experimental results indicated a higher level of phase noise than what was obtained through simulation. Notably, as the output frequency increased, there was a corresponding increase in the amount of phase noise. The maximum spur observedoccurred at the third harmonic, measuring -18.6 dBc, while the minimum spur appeared at the fourth harmonic, measuring -44.5 dBc.
Water Quality Assessment and Spatial Variation in Aba River Water, South-Eastern Nigeria
Authors: Wokeh O. K. , Okey-Wokeh C. G. , Orose E.
Published: April 2024

The status of the Aba freshwater ecosystem (river) was assessed for the influence of human activities at differentsections of the river and its attendant effects on water parameters. To achieve this, samples of water were collected monthly from January to June 2020 at three sampling stations marked A1, A2, and A3 and were analysed on-site for water, electrical conductivity (EC), dissolved oxygen (DO), pH, salinity, total dissolved solids (TDS) and temperature with the aid of a handheld multi-parameter kit. Biochemical oxygen demand (BOD) was fixed onsiteand taken to the laboratory along with samples for potentially toxic metals (PTMs), Cd, Cu, Pb, Fe, and Zn),which were analysed by standard analytical procedure.Statistical variation across the sampling hotspots was determined with a one-way analysis of variance. The results indicated the average values of pH were moderately low in all the stations with little statistically variation (p˃ 0.05) between samples. The mean EC indicated station A1 (1394.32±152) had the highest concentration, followed by station A2 (972.14±52.22), and A3 (496.16±72.10) was the lowest. The mean salinity, TDS and Cl- followed a similar pattern as EC, with significant differences (p ˂ 0.05) in all the stations. DO values for A3 (4.90±0.37) were the highest while for A1 (3.34±0.21) they were the least. The mean BOD results for station A1 (6.54±5.54) were the highest whereas for A3 (3.28±0.66) they were the lowest. The value of metals across the stations indicated higher occurrence pattern: Fe˃ Zn ˃Cu˃ Cd˃ Cr˃ Pb. Generally, the concentrations of physicochemical and potentially toxic metal parameters were above the threshold for surface water and this deduced that the river was contaminated and needed urgent remediation. Also, the government should regulate the discharges of industrial effluents, agricultural wastes and sewage into the water body to safeguard the river from further deterioration.
Evaluation of fungal permeated lignocellulosic filter for remediation of water pollutants
Authors: Titilawo M. A. , Adeyemi F. M. , Ajani T. F. , Ogunlana E. O. , Titilawo Y.
Published: April 2024

The use of biological techniques to remove pollutants from the environment has been long advocated. In this study, we assessed the efficacy of a fungal permeated lignocellulosic filter (mycofilter) in the removal of water pollutants using surface water as the test sample. A wild macrofungus was collected from a field within Osun State University, Oke-Baale, Osogbo, and cultured on potato dextrose agar. Identification was achieved using morphological and PCR techniques. Mycofilters (FCCs) were developed from pure macrofungus mycelium and diced pasteurized corncob (CC). Collected surface water (RW) was passedthrough three mycofilters, each with flow rates of 0.2, 0.5, and 1.0 ml/min. Diced pasteurized corncob (CC) was used as the negative control. Physicochemical parameters including pH, temperature, turbidity, cadmium, copper, iron, zinc, and lead, and microbial parameters i.e. total bacterial count (TBC) and Escherichia coli counts (ECC) of RW, CC, and FCC treated waters were determined. Phenotypically, the fungus was identified as Macrolepiota procera and yielded 650 bp by PCR product assessment on gel electrophoresis. Remarkably, FCC reduced the levels of turbidity, chemical, and microbial contaminants significantly at p = 0.001, < 0.05, and ≤ 0.002 respectively compared to CC. The flow rate of 0.2 ml/min was the most efficient in reducing contaminants in the RW. This study reveals the potential of the Macrolepiota procera permeated filter in reducing water contaminants.
Characterization of amorphous silicon nitride prepared from sand and coffee husk wastes by carbothermal reduction-nitridation
Authors: Ndung'u S. N. , Nthiga E. W. , Wanjau R. N.
Published: April 2024

The continued coffee demand in Kenya has amplified the generation of its husk wastes causing disposal problems. This has led to serious pollution to the environment. Therefore, developing a greener and cost-effective ways to handle these wastes is necessary. The current study entailed the use of extracted silica and coffee husk biochar as novel precursor materials for the synthesis of silicon nitride .....
Influence of Principals’ Provision of Welfare Services on Tutors’ Job Commitment in Primary Teachers Training Colleges in Eastern Region Kenya
Authors: Mbaka Kenkelvin Kimathi , Kalai Jeremiah M. , Mutegi Reuben G.
Published: April 2024

The purpose of the study was to investigate the influence of principals’ provision of welfare services on tutors’ job commitment in primary teachers training colleges in Eastern Region Kenya. The study was guided by the following objective: To determine the influence of principals’ provision of welfare services on tutors’ levels of job commitment in Primary Teachers Training Colleges in Eastern Region, Kenya. The Existence Relatedness and Growth Theory of Motivation guided the study. Descriptive survey design was used. For this study, the target population entailed five (5) Teacher Training College principals, 260 tutors and 1860 second year students of the five (5) public teachers training colleges in Eastern Region, Kenya. To sample the respondents, the researcher used census method to sample the 5 college principals, and used 50% to sample the tutors and 10% for second year students giving a sample size of 130 and 186 respectively. Simple random sampling was therefore used to select the tutors and students using replacement method. The instruments used were questionnaires for tutors and teacher trainees and interview guides for principals. Data was analyzed using descriptive (frequencies, means and standard deviations) and inferential statistics (p-values from ordinal logistic regression and independent sample t-test). The results were graphically visualized through frequency distribution tables, bar graphs and tables. Regression results showed that increasing provision of welfare services by principals by 1% would promote job commitment levels of tutors by approximately 122%. The study also revealed a positive and significant relationship between provision of welfare services (medical facilities, welfare group, free meals and housing facilities) by principals and the job commitment levels among tutors (r=0.3518436, p=4.336e-05), The results implying that provision of welfare services by the principals, increased the tutors’ level of both affective,continuance and normative job commitment. Based on the findings, the study recommended that through ministry of education, to have well placed sound policy to promote principals’ training on importance of provision of welfare services in order to enhance academic performance in Primary Teachers Education Examination as a result of tutors’ job commitment
Preperitoneal pelvic balloon tamponade—an effective intervention to control pelvic injury hemorrhage in a swine model
Authors: Jin Xiaogao , Chu Qinjun , Bing Hailong , Li Fang , Bai Jingyue , Lou Junge , Sun Liwei , Zhang Chenxi , Lin Lin , Li Liumei , Wang Haibo , Zhou Zhanfeng , Zhang Junfeng , Lian Hongkai
Published: April 2024

Objective: This study aimed to estimate the effects of the volume of preperitoneal balloon (PPB) on arterial and venous hemorrhage in a swine pelvic fracture model.

Methods: Twenty-four swine were randomized into 0-mL, 500-mL, 800-mL, and 1000-mL intra-hematoma PPB groups. They were subjected to open-book pelvic fracture and reproducible injuries in the external iliac artery and vein. The pelvic binder and IH-PPBs with different volumes of fluid were applied to control the active hemorrhage after arterial and venous injuries. The survival time and rate during 60-min observation and digital subtraction angiography (DSA) images were the primary endpoints in this study. Secondary endpoints included survival rate within 70 min, peritoneal pressure, hemodynamics, blood loss, infusion fluid, blood pH, and lactate concentration.

Results: Our results indicated that the 800-mL and 1000-mL groups had a higher survival rate (0%, 50%, 100% and 100% for 0, 500, 800, and 1000-mL groups respectively; p < 0.0001) and longer survival time (13.83 ± 2.64, 24.50 ± 6.29, 55.00 ± 6.33, and 60.00 ± 0.00 min for 0, 500, 800, and 1,000 groups respectively; p < 0.0005) than the 0-mL or 500-mL groups during the 60 min observation. Contrastingly, survival rate and time were comparable between 800-mL and 1000-mL groups during the 60-min observation. The IH-PPB volume was associated with an increase in the pressure of the balloon and the preperitoneal pressure but had no effect on the bladder pressure. Lastly, the 1000-mL group had a higher mean arterial pressure and systemic vascular resistance than the 800-mL group.

Conclusion: IH-PPB volume-dependently controls vascular bleeding after pelvic fracture in the swine model. IH-PPB with a volume of 800 mL and 1000 mL efficiently managed pelvic fracture-associated arterial and venous hemorrhage and enhanced survival time and rate in the swine model without evidences of visceral injury.
The phycosphere and its role in algal biofuel production
Authors: Yarbro Jake , Khorunzhy Emma , Boyle Nanette
Published: April 2024

Oleaginous microalgae have become a focus for large-scale biofuel production due to their ability to accumulate large quantities of lipids. However, production is currently limited by cost and predation. At present, algal biofuel cultivation is optimized through starvation, supplementing media with nutrients, or genetic engineering; these methods can often be costly with little to no increase in lipid production or the culture’s defense. Investigating the phycosphere of algal-bacterial interactions may overcome these current barriers to large-scale production. The phycosphere of algal-bacterial interactions have formed over millions of years through mutualistic and symbiotic relationships and can provide a more direct source of nutrients compared to adding the nutrients in bulk. The most promising of these interactions include the production of phytohormones and quorum signaling compounds that alter the behaviors of the consortia. Phytohormones can improve algal growth rates, lipid production, and stress resistance. Quorum signaling could create consortia capable of warding off invaders—such as rotifers—while self-regulating and altering behavior based on population density. Mechanisms within the algal phycosphere present many opportunities for the development of novel engineering strategies to further improve algal lipid production and operational costs. This review outlines previous preliminary phycosphere research as well as posing possible opportunities to be pursued in future biofuel production.
Case Report: Transcatheter aortic valve implantation using balloon-expandable bioprosthesis in patients with severe pure aortic regurgitation on noncalcified native valves: a series of cases
Authors: Santos Luciano de Moura , Luz Larissa Santos , Bastos Vinicius Lelis , Barcelos Tulio Assunção , Abreu Frederico André Alves , Beck Leonardo Cogo , Darnasser Mohammed Jamal Aldin Hilal , Cruz Francisco de Assis , Matos Luis Carlos Vieira , Carvalho Wenderval Borges
Published: April 2024

Background

For individuals with pure aortic regurgitation (AR), transcatheter aortic valve implantation (TAVI) is cautiously recommended only for those with a high or prohibitive surgical risk. We aimed to describe the results of a case series of transcatheter implantation of a balloon-expandable aortic valve bioprosthesis (BEV) for the treatment of noncalcified native valve AR.

Methods

From February 2022–November 2022, we performed TAVI in patients with severe pure AR. Cases were indicated on the basis of symptoms, high/prohibitive surgical risk, or patient refusal of conventional treatment.

Results

Five patients underwent successful TAVI. The mean age was 81.9 ± 6.6 years, 3 (60%) female and 5 (100%) in NYHA class III or IV. The baseline echocardiogram showed an ejection fraction of 49.0 ± 10.6% and left ventricular end-systolic diameter 28.5 ± 4.7 mm/m². The average area of the aortic annulus was 529.1 ± 47.0mm² and the area oversizing index was 17.6 ± 1.2%. In the 30-day follow-up, there were no cases of prosthesis embolization, annulus rupture, stroke, acute myocardial infarction, acute renal failure, hemorrhagic complication or death. One patient required a permanent pacemaker and another had a minor vascular complication. The clinical follow-up were 19.8 months (16.7–21.8). During this period, all patients remained alive and in NYHA class I or II. One of the patients developed a moderate paravalvular leak.

Conclusion

TAVI with a BEV proved to be safe and effective in this small case series of patients with noncalcified native valve AR in a follow-up longer than 1 year.
Case Report: Pulsed field ablation for epicardial right-sided accessory pathway
Authors: Haskova Jana , Peichl Petr , Borisincova Eva , Kautzner Josef
Published: April 2024

We present a case of a 32-year-old male with a history of palpitations and preexcitation on ECG who underwent altogether four failed catheter ablations using different approaches in the two other electrophysiology centers within two years. ECG showed overt preexcitation with a positive delta wave in lead I and negative in leads V1–V3, suggesting a right free wall accessory pathway. During the electrophysiological study, the accessory pathway was localized on the free lateral wall. However, the electrograms and mapping during atrial and ventricular pacing suggested the presence of true epicardial accessory pathway. Repeated radiofrequency energy delivery with the support of the steerable sheath and excellent contact (as assessed by intracardiac echocardiography) at the earliest ventricular activation was not successful. Therefore, the Farawave catheter (Boston Scientific, Inc) was used, and a flower configuration with the intention to cover the entire atrial attachment of the pathway during ventricular pacing was selected. Application of pulsed field resulted in interruption of accessory pathway conduction. An electrophysiological study one year later confirmed the persistent effect of ablation. This case illustrates the potential utility of pulsed field energy for the ablation of atrial insertion of the accessory pathway with an epicardial course. Such an approach can avoid epicardial mapping and access and may improve the safety of the procedure.
Automatic identification and quantification of volcanic hotspots in Alaska using HotLINK: the hotspot learning and identification network
Authors: Saunders-Shultz Pablo , Lopez Taryn , Dietterich Hannah , Girona Társilo
Published: April 2024

An increase in volcanic thermal emissions can indicate subsurface and surface processes that precede, or coincide with, volcanic eruptions. Space-borne infrared sensors can detect hotspots—defined here as localized volcanic thermal emissions—in near-real-time. However, automatic hotspot detection systems are needed to efficiently analyze the large quantities of data produced. While hotspots have been automatically detected for over 20 years with simple thresholding algorithms, new computer vision technologies, such as convolutional neural networks (CNNs), can enable improved detection capabilities. Here we introduce HotLINK: the Hotspot Learning and Identification Network, a CNN trained to detect hotspots with a dataset of −3,800 satellite-based, Visible Infrared Imaging Radiometer Suite (VIIRS) images from Mount Veniaminof and Mount Cleveland volcanoes, Alaska. We find that our model achieves an accuracy of 96% (F1-score 0.92) when evaluated on −1,700 unseen images from the same volcanoes, and 95% (F1-score 0.67) when evaluated on −3,000 images from six additional Alaska volcanoes (Augustine Volcano, Bogoslof Island, Okmok Caldera, Pavlof Volcano, Redoubt Volcano, Shishaldin Volcano). In comparison with an existing threshold-based hotspot detection algorithm, MIROVA (Coppola et al., Geological Society, London, Special Publications, 2016, 426, 181–205), our model detects 22% more hotspots and produces 12% fewer false positives. Additional testing on −700 labeled Moderate Resolution Imaging Spectroradiometer (MODIS) images from Mount Veniaminof demonstrates that our model is applicable to this sensor’s data as well, achieving an accuracy of 98% (F1-score 0.95). We apply HotLINK to 10 years of VIIRS data and 22 years of MODIS data for the eight aforementioned Alaska volcanoes and calculate the radiative power of detected hotspots. From these time series we find that HotLINK accurately characterizes background and eruptive periods, similar to MIROVA, but also detects more subtle warming signals, potentially related to volcanic unrest. We identify three advantages to our model over its predecessors: 1) the ability to detect more subtle volcanic hotspots and produce fewer false positives, especially in daytime images; 2) probabilistic predictions provide a measure of detection confidence; and 3) its transferability, i.e., the successful application to multiple sensors and multiple volcanoes without the need for threshold tuning, suggesting the potential for global application.
Rare earth element enrichment in coal and coal-adjacent strata of the Uinta Region, Utah and Colorado
Authors: Coe Haley H. , Birgenheier Lauren P. , Fernandez Diego P. , Gall Ryan D. , Vanden Berg Michael D. , Giebel Andrew
Published: April 2024

This study aims to quantify rare earth element enrichment within coal and coal-adjacent strata in the Uinta Region of central Utah and western Colorado. Rare earth elements are a subset of critical minerals as defined by the U.S. Geological Survey. These elements are used for a wide variety of applications, including renewable energy technology in the transition toward carbon-neutral energy. While rare earth element enrichment has been associated with Appalachian coals, there has been a more limited evaluation of western U.S. coals. Here, samples from six active mines, four idle/historical mines, four mine waste piles, and seven stratigraphically complete cores within the Uinta Region were geochemically evaluated using portable X-ray fluorescence (n = 3,113) and inductively coupled plasma-mass spectrometry (n = 145) elemental analytical methods. Results suggest that 24%–45% of stratigraphically coal-adjacent carbonaceous shale and siltstone units show rare earth element enrichment (>200 ppm), as do 100% of sampled igneous material. A small subset (5%–8%) of coal samples display rare earth element enrichment, specifically in cases containing volcanic ash. This study proposes two multi-step depositional and diagenetic models to explain the enrichment process, requiring the emplacement and mobilization of rare earth element source material due to hydrothermal and other external influences. Historical geochemical evaluations of Uinta Region coal and coal-adjacent data are sparse, emphasizing the statistical significance of this research. These results support the utilization of active mines and coal processing waste piles for the future of domestic rare earth element extraction, offering economic and environmental solutions to pressing global demands.
Unlock the potential for Saudi Arabian higher education: a systematic review of the benefits of ChatGPT
Authors: Faisal Eman
Published: April 2024

This systematic review investigates the potential benefits of integrating ChatGPT in higher education. Focusing on ChatGPT’s impact, the study identifies themes such as ChatGPT’s role in teaching and instruction, enhancing student learning and engagement, aiding language learning, and promoting inclusivity. The review underscores ChatGPT’s ability to reshape the educational landscape, improve research and writing, bridge language gaps, and address specific challenges. ChatGPT emerges as a transformative tool empowering educators and students, aligning with Saudi Arabia’s pursuit of academic excellence and future workforce readiness.
Evaluating game-based teaching systems in economics courses
Authors: Iannace Arturo Mariano , Bisanti Matteo , Piazzoli Andrea
Published: April 2024

The integration of games in education has garnered substantial interest. This study explores a game-based teaching system, a prototype megagame with RPG elements, within an economics course. Methodologically, we assessed the engagement of the course as a proxy for gauging the impact of the game on the learning process. The game involved 177 undergraduate students in thematic sessions, with 59 males and 118 females. Of these, only 114 filled out the pre-test, and 86 filled out the post-test, showing a dropout rate of 25%. The range of the age was between 19 and 21 years. We propose an evaluative framework through pre-post surveys. The theoretical analysis underscores the immersive potential of RPGs in educational contexts, while the results show a decrease in cognitive engagement and an increase in some elements of emotional engagement in students’ perceptions, despite high starting expectations by students. Thus, this research highlights the need for a more effective use of gaming as an educational tool by identifying and addressing these shortfalls through further studies, and for the subsequent broader implementation of GBL techniques.
Longitudinal predictors of reading and arithmetic at different attainment levels
Authors: Banfi Chiara , Jöbstl Viktoria , Göbel Silke M. , Landerl Karin
Published: April 2024

Reading and arithmetic are distinct academic skills that share similarities in skill acquisition and use. Previous research investigated the cognitive basis of associations and dissociations between reading and arithmetic by using either subtyping or dimensional approaches. In the current study, we aim to bridge the gap between these two approaches by investigating common and distinct predictors of reading and arithmetic at different performance levels with quantile regression models. This allowed us to look more closely at the lower tail of the ability distributions, and to test whether predictions for children with low reading and arithmetic fluency differed from the typical performance range. We analyzed longitudinal data of 357 children speaking English or German. Outcome variables were reading and arithmetic fluency assessed at the end of Grade 1, 2, and 3. Predictors were assessed in Grade 1. Results confirmed nonverbal IQ and working memory as domain-general predictors of reading and arithmetic. The association of reading and arithmetic was mainly explained by nonverbal IQ, phonological awareness, RAN and multi-digit transcoding. Across grades and performance levels, phonological awareness and RAN made a specific contribution to reading. Magnitude processing and multi-digit transcoding were specific predictors of arithmetic. Counting also made a specific prediction to arithmetic in Grade 3, but only in the low performance range. Our findings indicate partly distinct underlying cognitive mechanisms for reading and arithmetic. Shared predictors are involved in retrieval efficiency, language processing and cross-format integration. These results have important implications, as they suggest that most predictors are equally relevant for children with low, typical or even excellent reading and arithmetic fluency.
Fostering humanization in education: a scoping review on mindfulness and teacher education
Authors: Soares Filipa , Lopes Amélia , Serrão Carla , Ferreira Elisabete
Published: April 2024

The humanization of education is increasingly invoked as a counterpoint to the overly technical and instrumental view of education that has developed in recent decades. In this article, it is intended to contribute to identify ways toward education humanization through teacher education. As the research on humanization of education at the empirical level remains vague, studies on mindfulness in teacher education are taken as a first means of operationalizing research into the conditions of fostering reflection on the humanization of education in teacher education. As a step along this path a scoping review was conducted to map research on mindfulness in teacher education and its relationship with the humanization of education, guided by questions such as how MBAs have been conceptualized and their role in humanizing teacher education. The scoping review allowed the identification of 21 articles which were charted according to analytical frameworks regarding: the mindfulness conceptualization, chosen research paradigms, and the role given to mindfulness in teacher education. Findings suggest that the way mindfulness is conceptualized in research makes an essential difference in acknowledging its instrumental and/or transformative role in education. Transformative approaches may bring an added educational value, addressing the subjective, reflective, and critical dimensions of teacher education. From this point of view, mindfulness-based education practices could be a promising pathway to inform empirical research on the humanization of education through teacher education.
Why comparing matters – on case comparisons in organic chemistry
Authors: Graulich Nicole , Lieber Leonie
Published: April 2024

When working with domain-specific representations such as structural molecular representations and reaction mechanisms, learners need to be engaged in multiple cognitive operations, from attending to relevant areas of representations, linking implicit information to structural features, and making meaningful connections between information and reaction processes. For these processes, appropriate instruction, such as a clever task design, becomes a crucial factor for successful learning. Chemistry learning, and especially organic chemistry, merely addressed meaningful task design in classes, often using more reproduction-oriented predict-the-product tasks. In recent years, rethinking task design has become a major focus for instructional design in chemistry education research. Thus, this perspective aims to illustrate the theoretical underpinning of comparing cases from different perspectives, such as the structure-mapping theory, the cognitive load theory, and the variation theory, and outlines, based on the cognitive theory of multimedia learning, how instructors can support their students. Variations of this task design in the chemistry classroom and recommendations for teaching with case comparisons based on current state-of-the-art evidence from research studies in chemistry education research are provided.
The landscape of genetic variations in non-syndromic primary ovarian insufficiency in the MENA region: a systematic review
Authors: Allouch Asma , Al-Barazenji Tara , Al-Shafai Mashael , Abdallah Atiyeh M.
Published: April 2024

Introduction

Premature ovarian insufficiency (POI) is a primary cause of infertility with variable clinical manifestations. POI is a multifactorial disease with both environmental and known genetic etiologies, but data on the genetic variations associated with POI in the Middle East and North Africa (MENA) region are scarce. The aim of this study was to systematically review all known genetic causes of POI in the MENA region.

Methods

The PubMed, Science Direct, ProQuest, and Embase databases were searched from inception to December 2022 for all reports of genetic variants associated with POI in the MENA region. Clinical and genetic data were collected from eligible articles, and ClinVar and PubMed (dbSNP) were searched for variants.

Results

Of 1,803 studies, 25 met the inclusion criteria. Fifteen studies were case-control studies and ten were case reports representing 1,080 non-syndromic POI patients in total. Seventy-nine variants in 25 genes associated with POI were reported in ten MENA countries. Of the 79 variants, 46 were rare and 33 were common variants. Of the 46 rare variants, 19 were pathogenic or likely pathogenic according to ACMG classification guidelines and ClinVar. No clear phenotype-genotype association was observed. Male family members carrying pathogenic variants also had infertility problems.

Discussion

To our best knowledge, this is the first systematic review of the genetic variants associated with POI in the MENA region. Further functional studies are needed to assess the disease-causing molecular mechanisms of these variants. Knowledge of the genetic basis of POI in the Middle East could facilitate early detection of the condition and thus early implementation of therapeutic interventions, paving the way for precision medicine options in specific populations.