Central University of Venezuela

A preliminary stability and dispersion study for wave propagation problems is developed for mimetic finite difference discretizations. The discretization framework corresponds to the fourth-order staggered-grid Castillo-Grone operators that offer a sextuple of free parameters. The parameter-dependent mimetic stencils allow problem discretization at domain boundaries and at the neighbor grid cells. For arbitrary parameter sets, these boundary and near-boundary mimetic stencils are lateral, and we here draw first steps on the parametric dependency of the stability and dispersion properties of such discretizations. As a reference, our analyses also present results based on Castillo-Grone parameters leading to mimetic operators of minimum bandwidth that have been previously applied in similar physical problems. The most interior parameter-dependent mimetic stencils exhibit a specific Toeplitz-like structure, which reduces to the standard central finite difference formula for staggered differentiation at grid interior. Thus, our results apply to the whole discretization grid. The study done for the 1-D problem could be applied to the discretization of a free surface boundary condition along an orthogonal gridline to this boundary.

The objective of this study was based on the application of the response surface methodology (RSM) for yield optimization in maize (Zea mays L.). The hybrid INIA SQ-1 was used, and the Response Surface Methodology was used using the Box-Behnken design (DBB), with which the following factors were evaluated: plant density, nitrogen (N) dose and phosphorus (P) dose at three levels each; for the optimization of the response variables: “yield” (kg.ha-1) and the “number of grains per square meter” (g.m2). The response surface method provided a statistically validated predictive model, which through adjustments was adapted to an established optimization process. For the variable “yield”, a maximum response was found with the application of 150 Kg.ha-1 of N and 90 kg.ha-1 of P. In relation to the number of grains per square meter (g.m2), the optimum was obtained using 75,000 plants.ha-1 and an applied dose of 150 kg.ha-1.

The objective of this review is to present soil and pasture evaluation studies using georeferenced aerial photographs captured by sensors on board drones and analyzed using the Geographic Information System (GIS) to develop strategies for use in the management of pastures and farm potential. The use of intensive grazing systems requires advanced knowledge for efficient management, and smart and precision agriculture represents a strategy to reduce costs. Using GIS and drones, an immediate comprehensive diagnosis is obtained, such as quantification of the degradation of a pasture or farm, distribution of botanical composition, and variability of soil and pasture nutrients to generate fertilization plans by specific area (precision agriculture).

The aim of this study was to describe the treatment of permanent teeth diagnosed with irreversible pulpitis, which can be effectively managed with partial or total pulpotomy. This alternative approach has shown great clinical and radiographic success in the long term compared to traditional pulpectomies. In this series of clinical cases, all the teeth exhibited symptoms of intense pain upon exposure to cold and at night. The clinical examination revealed extensive caries, while radiographic imaging showed radiolucent lesions in contact with the pulp chamber, indicating symptomatic irreversible pulpitis. The chosen treatment approach was either partial or total pulpotomy. The tooth was anesthetized, and the operative field was isolated and disinfected. After removing caries with a sterile round drill, the area was rinsed with sodium hypochlorite. In some cases, a portion of the pulp tissue was removed, while in others, the entire tissue of the pulp chamber was extracted using diamond burs. Hemostasis was achieved by applying sterile cotton pellets for 2 to 6 minutes. Following that, the tissue exhibited no signs of bleeding. Bioceramic cements were used, and the tooth was definitively restored. Periodic follow-up examinations were conducted, consistently showing positive pulp responses and no evidence of periradicular radiolucent lesions on radiographs.

The Global Health Consortium at Florida International University developed an end-to-end solution framework based on the input of a diverse panel of experts from middle-income country (MIC) government agencies, public health think tanks, academia, and nonprofit organizations to identify mechanisms to help MIC governments and stakeholders increase access to novel vaccines for infectious diseases. The resultant layout can be deployed to improve vaccine discovery and development, strengthen regulatory processes, and boost vaccine production, access, and implementation. Mechanisms include policies and incentives MIC governments can use to stimulate vaccine investment and activity, as well as actions government agencies can take together with other stakeholders to coordinate efforts or build capabilities. Through a series of individual virtual interviews, we engaged diverse experts from MIC government agencies, public health think tanks, academia, and nonprofit organizations who understand the vaccine ecosystem, immunization policies, and population health financing at global, regional, and country levels. Responses were mapped, and in-depth questions were prepared for a group virtual discussion. This paper is the result of such a group discussion. The panel identified clear opportunities for MICs to improve locally-driven innovations and future access to novel vaccines. It proposes a solution framework for countries considering investing in vaccine research and development and innovation to use as a guide to evaluate the steps they could take to improve such an environment and incentivize innovation in vaccine development. It is hoped that this end-to-end solution framework will become a key resource to help MICs strengthen policies and take more actions to make such improvements.

This research aimed to determine the susceptibility of Aspergil-lus spp. to four antifungal agents using the Etest® method in several clinical samples (respiratory samples, soft tissue, otic tissue, and ocular tissue, among others) from a private health center in Venezuela. Thirty-three strains were evaluated: 11 Aspergillus section Flavi, eight Aspergillus section Fumigati, six Aspergillus section Nigri, four Aspergillus section Terrei, and four Aspergillus spp. A 0.5 McFarland standard suspension of a 5-day culture of each Aspergillusstrain was prepared on Potato Dextrose agar and then inoculated on Sabouraud agar plates with 2% glucose. Voriconazole (VCZ), amphotericin B (AMB), caspo-fungin (CAS), and posaconazole (PCZ) were tested. Minimal inhibitory concen-trations (MIC) in μg/mL were determined after 24 and 48 hours of incubation at 35 °C and th range (R), geometric mean (GM), MIC50, and MIC90 were calcu-lated. The results for the 33 Aspergillus spp. tested after 24 h were the follow-ing: VCZ (R = 0.031- 16; GM = 0.145; MIC50 = 0.125 and MIC90 = 0.5), AMB (R = 0.031-16; GM = 0.644; MIC50 = 0.5 and MIC90 = 8), CAS (R = 0.031-16; GM = 0.1076; MIC50 = 0.063 and MIC90 = 1), PCZ (R =0.031 - 0.5; GM = 0.0755; MIC50 = 0.063 and MIC90 = 0.25). This investigation allowed assessing the an-tifungal susceptibility profiles of Aspergillus spp. isolated from clinical samples by the Etest® method, which is practical, reproducible and easy to perform in microbiology laboratories.

Here we examine properties of MeV electron microbursts to better understand their generation mechanisms. Using 15 years of data from Solar, Anomalous, Magnetospheric Particles Explorer/Heavy Ion Large Telescope, >1 MeV microburst repetition periods (time spacing between bursts) are examined and clear dependencies on Auroral Electrojet (AE), L shell, and magnetic local time (MLT) are discovered. Microburst repetition periods are shortest around 0–6 hr MLT and 4–5 L shell, and grow longer toward the day and afternoon sectors and larger L shells. Shorter repetition periods (<1 s) are also found to be more common during higher AE, while longer periods (>10 s) more common during quiet times. The microburst repetition period distributions are compared directly to those of rising tone chorus wave elements and found to be similar in the night, dawn and day MLT sectors, suggesting chorus wave repetition periods are likely directly controlling those of microburst precipitation. However, dusk‐side distributions differ, indicating that the dusk‐side microbursts properties may be controlled by other processes.

The chiral‐induced spin selectivity effect (CISS) is a breakthrough phenomenon that has revolutionized the field of electrocatalysis. We report the first study on the electron spin‐dependent electrocatalysis for the oxygen reduction reaction, ORR, using iron phthalocyanine, FePc, a well‐known molecular catalyst for this reaction. The FePc complex belongs to the non‐precious catalysts group, whose active site, FeN4, emulates catalytic centers of biocatalysts such as Cytochrome C. This study presents an experimental platform involving FePc self‐assembled to a gold electrode surface using chiral peptides (L and D enantiomers), i.e., chiro‐self‐assembled FePc systems (CSAFePc). The chiral peptides behave as spin filters axial ligands of the FePc. One of the main findings is that the peptides' handedness and length in CSAFePc can optimize the kinetics and thermodynamic factors governing ORR. Moreover, the D‐enantiomer promotes the highest electrocatalytic activity of FePc for ORR, shifting the onset potential up to 1.01 V vs. RHE in an alkaline medium, a potential close to the reversible potential of the O2/H2O couple. Therefore, this work has exciting implications for developing highly efficient and bioinspired catalysts, considering that, in biological organisms, biocatalysts that promote O2 reduction to water comprise L‐enantiomers.

The chiral‐induced spin selectivity effect (CISS) is a breakthrough phenomenon that has revolutionized the field of electrocatalysis. We report the first study on the electron spin‐dependent electrocatalysis for the oxygen reduction reaction, ORR, using iron phthalocyanine, FePc, a well‐known molecular catalyst for this reaction. The FePc complex belongs to the non‐precious catalysts group, whose active site, FeN4, emulates catalytic centers of biocatalysts such as Cytochrome C. This study presents an experimental platform involving FePc self‐assembled to a gold electrode surface using chiral peptides (L and D enantiomers), i.e., chiro‐self‐assembled FePc systems (CSAFePc). The chiral peptides behave as spin filters axial ligands of the FePc. One of the main findings is that the peptides' handedness and length in CSAFePc can optimize the kinetics and thermodynamic factors governing ORR. Moreover, the D‐enantiomer promotes the highest electrocatalytic activity of FePc for ORR, shifting the onset potential up to 1.01 V vs. RHE in an alkaline medium, a potential close to the reversible potential of the O2/H2O couple. Therefore, this work has exciting implications for developing highly efficient and bioinspired catalysts, considering that, in biological organisms, biocatalysts that promote O2 reduction to water comprise L‐enantiomers.

Introduction Studies evaluating the rate and histology of appendiceal neoplasms between complicated and uncomplicated appendicitis include a small number of patients. Therefore, we sought a meta-analysis and systematic review comparing the rates and types of appendiceal neoplasm between complicated and uncomplicated appendicitis. Methods We included articles published from the time of inception of the datasets to September 30, 2022. The electronic databases included English publications in Ovid MEDLINE In-Process & Other Non-Indexed Citations, Ovid MEDLINE, Ovid EMBASE, and Scopus. Results A total of 4962 patients with appendicitis enrolled in 4 comparative studies were included. The mean age was 43.55 years (16- 94), and half were male (51%). Based on intra-operative findings, 1394 (38%) had complicated appendicitis, and 3558 (62%) had uncomplicated appendicitis. The overall incidence rate of neoplasm was 1.98%. No significant difference was found in the incidence rate of appendiceal neoplasm between complicated (3.29%) and uncomplicated (1.49%) appendicitis (OR 0.44, 95% CI 0.16- 1.23; p < 0.087; I2 = 54.9%). The most common appendiceal neoplasms were Neuroendocrine Tumors (NET) (49.21%), Nonmucinous Adenocarcinoma (24.24%), Mixed Adeno-Neuroendocrine Tumor (MANEC) (11.40%), Mucinous Adenocarcinoma (4.44%). There was a significant difference between complicated and uncomplicated appendicitis in rates of adenocarcinoma (50% vs. 13%), NET (31% vs. 74%), MANEC (19% vs. 13%) (P < 0.001). Conclusion While there was no significant difference in the overall neoplasm rate between complicated and uncomplicated appendicitis, the NET rate was significantly higher in uncomplicated appendicitis. In comparison, the Adenocarcinoma rate was considerably higher in Complicated appendicitis. These findings emphasize the importance of evaluating risk factors for neoplasm when considering appendectomy in patients with appendicitis.

Background The association between conventional transvenous pacemaker leads and tricuspid regurgitation (TR) has been well described. Leadless pacemakers (LP) have risen as an alternative to conventional transvenous pacemakers in order to avoid lead associated complications. Prior studies have included a mix of leadless pacemaker types including: Nanostim, Micra, etc. This is the first study exploring only one model of LP. Purpose The purpose of the study was to investigate the impact of leadless pacemaker therapy on tricuspid regurgitation. Methods Adult patients who underwent Micra leadless pacemaker implantation at a single center from 2016 to 2022 were identified retrospectively. Patients who had an echocardiogram prior to the procedure and within 24 months after the procedure were included. Echocardiograms were reviewed to assess for change in presence or in severity of tricuspid regurgitation. Results There were 310 patients in total who received LP at our hospital. Of these, 104 met inclusion criteria. 189 patients were excluded because they did not have an echocardiogram before or after the procedure. 17 more were excluded because their post procedure echo was done more than 2 years later. The average age of our patient population was 78. Of the 104 total patients, 97 had some TR before LP implantation (Trace 41%, Trace-Mild 4%, Mild 31%, Mild-Moderate 7%, Moderate 13%, Moderate-Severe 1%, Severe 2%). After implantation, 34 patients had worsening TR (33%), 23 patients had improved TR (22%), and 47 patients had no change in TR severity (45%) p=0.053. Conclusion Overall, the results did not show a statistically significant improvement or worsening in TR severity after LP implantation. Further studies should be done to validate these findings, to evaluate the effect of a larger sample size, and to examine whether controlling for additional confounders maintains or contradicts this finding.

ARTICLE Mapping density, diversity and species-richness of the Amazon tree flora Using 2.046 botanically-inventoried tree plots across the largest tropical forest on Earth, we mapped tree species-diversity and tree species-richness at 0.1-degree resolution, and investigated drivers for diversity and richness. Using only location, stratified by forest type, as predictor, our spatial model, to the best of our knowledge, provides the most accurate map of tree diversity in Amazonia to date, explaining approximately 70% of the tree diversity and species-richness. Large soil-forest combinations determine a significant percentage of the variation in tree species-richness and tree alpha-diversity in Amazonian forest-plots. We suggest that the size and fragmentation of these systems drive their large-scale diversity patterns and hence local diversity. A model not using location but cumulative water deficit, tree density, and temperature seasonality explains 47% of the tree species-richness in the terra-firme forest in Amazonia. Over large areas across Amazonia, residuals of this relationship are small and poorly spatially structured, suggesting that much of the residual variation may be local. The Guyana Shield area has consistently negative residuals, showing that this area has lower tree species-richness than expected by our models. We provide extensive plot meta-data, including tree density, tree alpha-diversity and tree species-richness results and gridded maps at 0.1-degree resolution.

This study combines the use of multi‐objective decision trees (MODT) and a fuzzy TOPSIS approach to cope with sequential decision‐making under uncertainty with multiple conflicting objectives. To this aim, the MODT generates a Pareto‐optimal frontier of solutions for competing objectives, while fuzzy TOPSIS helps assess the noninferior solutions and assign weights to the objectives by considering possible uncertainties in outcomes as well as potential linguistic expression. The proposed approach is illustrated with a temporal decision problem concerning climate‐driven refugee resettlement, taking into consideration the challenges of global warming and system interdependencies in an uncertain context. The fuzzy TOPSIS approach was illustrated using two different procedures, and the procedure based on vector normalisation graphically depicts the fuzzy triangular representation of the final ranking.

Background To describe demographic and clinicopathological aspects of a South-American cohort of incipient oral squamous cell carcinoma patients. Methods A cross-sectional, observational study was performed to assess demographic and clinicopathological characteristics of incipient oral squamous cell carcinoma patients from 6 South-American institutions. Results One hundred and seven patients within the histopathological spectrum of incipient oral squamous cell carcinoma (in-situ and microinvasive) were included. Fifty-eight (54.2%) patients were men with a mean age of 60.69 years. Forty-nine (45.8%) and thirty-nine (36.5%) patients had history of tobacco and alcohol use, respectively. Clinically, most of the lesions were plaques (82.2%), ≥ 2 cm in extension (72%), affecting the lateral border of the tongue (55.1%), and soft palate (12.1%) with a mixed (white and red) appearance. Eighty-two (76.7%) lesions were predominantly white and 25 (23.3%) predominantly red. Conclusions To the best of our knowledge, this is the largest cohort of incipient oral squamous cell carcinoma patients, which raises awareness of clinicians’ inspection acuteness by demonstrating the most frequent clinical aspects of this disease, potentially improving oral cancer secondary prevention strategies.

This article presents attitudes and practices regarding COVID-19 vaccination in the South American population. The study collected data from a self-administered survey distributed through social media platforms between February and April 2022 (N = 6555). The survey included questions related to participants’ sociodemographic background, flu vaccination practices, sources of information about COVID-19, and opinions regarding pandemic management and vaccination against SARS-CoV-2. The respondents agreed with the statement that COVID-19 vaccines were necessary (86.4%), effective (79.8%), safe (79.1%), and should be mandatory (64%). Overall, 83.4% accepted vaccination and 12.3% refused it completely. Main rejection reasons were safety (65.8%) and efficacy (54.9%) issues, and rushed development and approvals (49.1%). Vaccine uptake was associated with being ≥60 years, being a healthcare worker, previous influenza vaccine uptake, adherence to preventive measures, the death of ≥1 close people from COVID-19, and being informed through mass media or health authorities’ channels. Vaccine uptake inversely correlated with male gender, low educational level, and use of closed social networks for COVID-19 information purposes. This study provides valuable insights into COVID-19 vaccination attitudes and practices in South America that may be used to promote vaccine uptake in the region. Higher COVID-19 vaccination acceptance among people with previously acquired prevention habits reinforces the importance of routine health promotion strategies.

Cardiovascular disease has remained one of the leading causes of mortality in the world. The basic pathophysiology of coronary artery disease (CAD) is a reduction of the blood flow in coronary vessels, leading to restricted blood flow to the heart muscle. Both modifiable and non-modifiable risk factors contribute to its multifactorial etiology. The clinical presentation ranges from asymptomatic to typical symptoms like chest pain, shortness of breath, and left arm or jaw pain. The purpose of this review is to investigate and analyze the variation of CAD depending on the biological sex, age, race, or ethnicity and how it might differ in the studied population while comparing the symptoms and prognosis of CAD. For this research, PubMed’s database was used. A total of 926 articles were selected using pre-determined inclusion and exclusion criteria, with 74 articles eligible to be included in the narrative review. Studies were selected from the general population of patients with CAD, regardless of their severity, stage of diagnosis, and treatment plan. The scale for the assessment of non-systematic review articles (SANRA) was used to assess the quality of the study. As humans age, the incidence of CAD increases, and people over 75 are more likely to have multiple-vessel CAD. It has been observed that South Asians have the highest rate of CAD at 24%, while the White population has the lowest at 8%. The prevalence of CAD also depends on race, with the White population having the lowest rate at 3.2%, followed by Hispanics at 5%, Black women at 5.2%, and Black men at 5.7%. Younger Black women tend to have more chest pain. Men with CAD commonly experience chest pain, and women are more likely to present with atypical symptoms. Modifiable risk factors such as smoking and alcoholism are more commonly observed in young men than in young women. Coronary artery disease in the elderly, female, minority, and Black patients is associated with a higher mortality rate. Acknowledging the prevalence of certain risk factors, signs, results, and responses to treatment in certain socio-demographic groups, as well as the provision and accessibility of diagnosis and treatment, would lead to a better outcome for all individuals. The impact of this shift can range from an earlier diagnosis of CAD to a faster and more customized treatment plan tailored to each patient's individual requirements.