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result(s) for
"Alvarez-Nuñez, Guillermo"
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Sensory interference shapes habitat suitability for an acoustically specialized predator
by
Alvarez-Nuñez, Guillermo
,
Jenkins, Julianna M. A.
,
Lesmeister, Damon B.
in
631/158
,
631/601
,
704/158
2025
Ambient acoustic conditions shape how animals perceive and interact with their environments, yet their role in structuring space use remains underexplored. Noise can mask biologically informative sounds which can impact foraging success, physiological fitness, and displace animals from viable habitat. Here, we test how landscape variables and soundscape characteristics across a mixed-use forest landscape affect spatial distribution of a nocturnal predator with specialized hearing. We used passive acoustic recordings to assess the effects of noise levels within biologically relevant frequency ranges on landscape use of the northern saw-whet owl (
Aegolius acadicus
) across 276 sites in Oregon, USA. Owl landscape use declined with increasing noise levels in the 1.60–7.10 kHz band, corresponding with species peak auditory sensitivity. In contrast, general low-frequency sound (0.25–1.00 kHz) was a poor predictor of landscape use but negatively affected acoustic detection probability. These results provide evidence that sensory masking from ambient soundscapes can constrain the realized acoustic niche and drive avoidance of otherwise suitable habitat. Our findings highlight the importance of considering full-spectrum acoustic environments in spatial ecology and suggest that species distributions are shaped not only by physical habitat but also by the perceptual accessibility of ecological information.
Journal Article
A New Computational Tool for the Development of Advanced Exergy Analysis and LCA on Single Effect LiBr–H2O Solar Absorption Refrigeration System
by
Alvarez, José R. Nuñez
,
Caratt Ortiz, Jean
,
Restrepo, Rafael Ramírez
in
Absorption cooling
,
Air conditioning
,
Alternative energy sources
2021
A single effect LiBr–H2O absorption refrigeration system coupled with a solar collector and a storage tank was studied to develop an assessment tool using the built-in App Designer in MATLAB®. The model is developed using balances of mass, energy, and species conservation in the components of the absorption cooling system, taking into account the effect of external streams through temperature and pressure drop. The whole system, coupled with the solar energy harvesting arrangement, is modeled for 24 h of operation with changes on an hourly basis based on ambient temperature, cooling system load demand, and hourly solar irradiation, which is measured and recorded by national weather institutes sources. Test through simulations and validation procedures are carried out with acknowledged scientific articles. These show 2.65% of maximum relative error on the energy analysis with respect to cited authors. The environmental conditions used in the study were evaluated in Barranquilla, Colombia, with datasets of the Institute of Hydrology, Meteorology and Environmental Studies (IDEAM), considering multiannual average hourly basis solar irradiation. This allowed the authors to obtain the behavior of the surface temperature of the water in the tank, COP, and exergy efficiency of the system. The simulations also stated the generator as the biggest source of irreversibility with around 45.53% of total exergy destruction in the inner cycle without considering the solar array, in which case the solar array would present the most exergy destruction.
Journal Article
Energy, Economic, and Environmental Evaluation of a Proposed Solar-Wind Power On-grid System Using HOMER Pro®: A Case Study in Colombia
by
Antonio Barrozo Budes, Farid
,
Valencia Ochoa, Guillermo
,
Obregon, Luis Guillermo
in
economic evaluation
,
energy efficiency
,
environmental impact
2020
The electrical sector in the Caribbean region of Colombia is currently facing problems that affect its reliability. Many thermo-electric plants are required to fill the gap and ensure energy supply. This paper thus proposes a hybrid renewable energy generation plant that could supply a percentage of the total energy demand and reduce the environmental impact of conventional energy generation. The hybrid plant works with a photovoltaic (PV) system and wind turbine systems, connected in parallel with the grid to supply a renewable fraction of the total energy demand. The investigation was conducted in three steps: the first stage determined locations where the energy system was able to take advantage of renewable sources, the second identified a location that could work more efficiently from an economic perspective, and finally, the third step estimated the number of PV solar panels and wind turbines required to guarantee optimal functioning for this location using, as a main method of calculation, the software HOMER pro® for hybrid optimization with multiple energy resources. The proposed system is expected to not only limit environmental impacts but also decrease total costs of electric grid consumption from thermoelectric plants. The simulations helped identify Puerto Bolivar, Colombia, as the location where the hybrid plant made the best use of non-conventional resources of energy. However, Rancho Grande was found to offer the system more efficiency, while generating a considerable amount of energy at the lowest possible cost. An optimal combination was also obtained—441 PV arrays and 3 wind turbines, resulting in a net present cost (NPC) of $11.8 million and low CO2 production of 244.1 tons per year.
Journal Article
TLR expression in peripheral monocyte subsets of patients with idiopathic inflammatory myopathies: association with clinical and immunological features
by
Nuñez-Alvarez, Carlos
,
Juarez-Vega, Guillermo
,
Carrillo-Vazquez, Daniel Alberto
in
Antigens
,
Autoimmune diseases
,
Biomedical and Life Sciences
2020
Background
Monocytes and toll-like receptors (TLR) have been found in the inflammatory infiltrate of muscle biopsies in patients with idiopathic inflammatory myopathies (IIM), suggesting an important role of these cells in the pathogenesis of myositis. The monocyte subsets, their TLR expression in peripheral blood and their relationship with the clinical characteristics of patients with IIM has not been addressed.
Methods
We recruited 45 patients with IIM diagnosis and 15 age and sex-adjusted healthy controls. We assessed the disease activity and damage, performed a nailfold capillaroscopy and registered the cardio-pulmonary parameters from the medical charts. Monocyte subsets, their expression of TLR2 and TLR4 and the serum Th1/Th2/Th17 cytokines levels were evaluated by flow cytometry. We expressed quantitative variables as medians and interquartile ranges (IQR) or minimum and maximum (min–max). Differences between groups were assessed with Mann–Whitney U and the Kruskal–Wallis tests. Correlation between quantitative variables was assessed with Spearman Rho.
Results
Twenty-nine patients were women (64.4%) and 32 (71.1%) had dermatomyositis. In comparison to healthy controls, patients with active IIM had a higher percentage of intermediate monocytes and lower amounts of classical monocytes. Patients with IIM had a higher expression of TLR4 in all their monocyte subsets, regardless of disease activity and prednisone treatment. Serum IL-6 correlated with the TLR2 expression in every monocyte subset and the expression of TLR2 in intermediate monocytes was higher among patients with dysphagia. Subjects with nailfold capillaroscopy abnormalities had a higher amount of TLR2+ classical and non-classical monocytes and those with interstitial lung disease (ILD) had a higher percentage of TLR4+ non-classical monocytes. The classical and intermediate monocytes from patients with anti Mi2 antibodies had a higher expression of TLR4. The percentage of intermediate monocytes and the expression of TLR4 in all monocyte subsets showed a good diagnostic capacity in patients with IIM.
Conclusion
Patients with IIM have a differential pool of monocyte subsets with an enhanced expression of TLR2 and TLR4, which correlates with disease activity and distinctive clinical features including dysphagia, ILD, vasculopathy, and pro-inflammatory cytokines. These immunological features might be useful as a potential diagnostic tool as well as novel disease activity biomarkers in IIM.
Journal Article
Influence of ambient temperature in the city of Portoviejo, Ecuador on the energy performance of photovoltaic modules
by
Rodríguez-Gámez, María
,
Vázquez Pérez, Antonio
,
Epeni-Tombo, Genial Belvinel
in
Alternative energy sources
,
Ambient temperature
,
Electric potential
2023
The research analyzes the influence of the average temperature on the performance of specific photovoltaic solar modules under the environmental conditions of the city of Portoviejo, province of Manabí, Ecuador. The research is carried out using the qualitative methodology. Its main objective is to determine the influence of temperature on the energy performance of photovoltaic modules under the region's environmental conditions. Two electrical diagrams with different configurations were designed, which were analyzed and simulated using the MATLAB Simulink software. The results obtained show the direct relationship between the electrical parameters of voltage, current intensity, and power with the temperature value on the surface of the modules. It is concluded that the modules generate a higher value of voltage, electric current intensity, and electric power at a lower temperature, regardless of the level of solar irradiation they receive.
Journal Article
RESEARCH EVOLUTION ON RENEWABLE ENERGIES RESOURCES FROM 2007 TO 2017: A COMPARATIVE STUDY ON SOLAR, GEOTHERMAL, WIND AND BIOMASS ENERGY
by
Acevedo, Carlos
,
Alvarez, Jose Nunez
,
Ochoa, Guillermo Valencia
in
Bibliometrics
,
Biomass energy
,
Geothermal power
2019
This article presents a bibliometric analysis of trends and the research state on the main renewable energies based on information obtained from the SCIE / SSCI database for the period 2007-2017. The analysis is aimed at solar energy, geothermal energy, wind energy and biomass energy source. The results generated from the bibliometric techniques used allowed to obtain the behavior of the publications production and the influence that different countries and universities have on this subject. From the 10,363 publications, the 87.5% are journal articles and the 98% are in English language. In addition, 49.03% of the publications corresponded to solar energy, 33.83% to wind energy, 12.77% to biomass and 4.37% to geothermal energy. In the ten years analyzed, the United States has been the most influential country in this research area, presenting the largest volume of publications in each of the renewable energies source studied. The results of this paper provide to energy researchers a relevant overview of the tendencies and scope of the main renewable energies worldwide. In addition, to support scientific decision and prospective investment in research center, relevant data are presented on the countries producing these renewable energies and their relationship with the production of publications.
Journal Article
Neutrophil Extracellular Traps Contribute to COVID-19 Hyperinflammation and Humoral Autoimmunity
by
Núñez-Álvarez, Carlos
,
Alcalá-Carmona, Beatriz
,
Lira-Luna, Jaquelin
in
Antibodies
,
Antineutrophil cytoplasmic antibodies
,
Antinuclear antibodies
2021
The coronavirus disease 2019 (COVID-19) is related to enhanced production of NETs, and autoimmune/autoinflammatory phenomena. We evaluated the proportion of low-density granulocytes (LDG) by flow cytometry, and their capacity to produce NETs was compared with that of conventional neutrophils. NETs and their protein cargo were quantified by confocal microscopy and ELISA. Antinuclear antibodies (ANA), anti-neutrophil cytoplasmic antibodies (ANCA) and the degradation capacity of NETs were addressed in serum. MILLIPLEX assay was used to assess the cytokine levels in macrophages’ supernatant and serum. We found a higher proportion of LDG in severe and critical COVID-19 which correlated with severity and inflammatory markers. Severe/critical COVID-19 patients had higher plasmatic NE, LL-37 and HMGB1-DNA complexes, whilst ISG-15-DNA complexes were lower in severe patients. Sera from severe/critical COVID-19 patients had lower degradation capacity of NETs, which was reverted after adding hrDNase. Anti-NET antibodies were found in COVID-19, which correlated with ANA and ANCA positivity. NET stimuli enhanced the secretion of cytokines in macrophages. This study unveils the role of COVID-19 NETs as inducers of pro-inflammatory and autoimmune responses. The deficient degradation capacity of NETs may contribute to the accumulation of these structures and anti-NET antibodies are related to the presence of autoantibodies.
Journal Article
Colchicine Is Safe Though Ineffective in the Treatment of Severe COVID-19: a Randomized Clinical Trial (COLCHIVID)
by
González-Lara, Fernanda
,
Núñez-Álvarez, Carlos
,
Plata-Corona, Juan Carlos
in
Anti-inflammatory agents
,
Clinical trials
,
Colchicine
2022
BackgroundColchicine is an available, safe, and effective anti-inflammatory drug and has been suggested as a COVID-19 treatment, but its usefulness in hospitalized severe COVID-19 patients has not been thoroughly demonstrated.ObjectiveTo address the safety and efficacy of colchicine in hospitalized patients with severe COVID-19.DesignWe conducted a triple-blind parallel non-stratified placebo-controlled clinical trial.ParticipantsWe recruited 116 hospitalized patients with severe COVID-19 in Mexico.InterventionsPatients were randomized to receive 1.5 mg of colchicine or placebo at the time of the recruitment in the study (baseline) and 0.5 mg BID PO to complete 10 days of treatment.Main MeasuresThe primary composite outcome was the progression to critical disease or death. Besides, we evaluated immunological features at baseline and after recovery or disease progression in 20 patients.Key ResultsFifty-six patients were allocated to colchicine and 60 patients received placebo. The study was suspended after the second interim analysis demonstrated colchicine had no effect on the primary outcome (OR 0.83, 95%CI 0.35–1.93, P = 0.67), nor in the days of ICU and hospital stays. Adverse events were similar between groups (OR 1.63, 95% CI 0.66–3.88, P = 0.37). After colchicine treatment, patients had higher BUN and lower serum levels of IL-8, IL-12p70, and IL-17A.ConclusionsColchicine is safe but not effective in the treatment of severe COVID-19.Trial RegistrationClinicalTrials.gov Identifier: NCT04367168.
Journal Article
Novel Clinical, Immunological, and Metabolic Features Associated with Persistent Post-Acute COVID-19 Syndrome
by
Maravillas-Montero, José L.
,
Núñez-Álvarez, Carlos
,
Alcalá-Carmona, Beatriz
in
Adult
,
Aged
,
Biomarkers
2024
The coronavirus disease 2019 (COVID-19) survivors are frequently observed to present persistent symptoms constituting what has been called “post-acute COVID-19 syndrome” (PACS) or “long COVID-19”. Some clinical risk factors have been identified to be associated with PACS development; however, specific mechanisms responsible for PACS pathology remain unknown. This study investigates clinical, immunological, and metabolomic risk factors associated with post-acute COVID-19 syndrome (PACS) in 51 patients, assessed 7–19 months after acute infection. Among the participants, 62.7% were male and 37.2% were female, with an average age of 47.8 years. At the follow-up, 37.2% met the criteria for PACS, revealing significant differences in immunological and metabolomic profiles at the time of acute infection. Patients with PACS were characterized by elevated levels of mature low-density granulocytes (LDGs), interleukin-8 (IL-8), pyruvate, pseudouridine, and cystine. Baseline multivariate analysis showed increased pyruvate and decreased alpha tocopherol levels. At follow-up, there was a decrease in absolute B lymphocytes and an increase in non-classical monocytes and 3-hydroxyisovaleric acid levels. These findings suggest that specific immunological and metabolomic markers during acute infection can help identify patients at higher risk of developing persistent PACS.
Journal Article
Clinical and immunological features associated to the development of a sustained immune humoral response in COVID-19 patients: Results from a cohort study
by
Lomelín-Gascón, Julieta
,
Núñez-Álvarez, Carlos
,
Cervantes-Díaz, Rodrigo
in
anti-cellular antibodies
,
Antibodies
,
Antibody response
2022
BackgroundUntil now, most of the research addressing long-term humoral responses in coronavirus disease 2019 (COVID-19) had only evaluated the serum titers of anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgGs, without the assessment of the baseline antiviral clinical and immune profile, which is the aim of this study and may be the key factor leading to a broad and sustained antibody response.MethodsWe included 103 patients with COVID-19. When the patients sought medical attention (baseline), a blood sample was drawn to perform immunophenotype of lymphocytes by flow cytometry. The patients were assessed 15 days after baseline and then every month until the third month, followed by a last visit 6 months after recruitment. We evaluated the anti-SARS-COV-2 IgG at all time points, and the serum levels of cytokines, chemokines, anti-cellular (AC) antibodies and neutrophil extracellular traps were also assessed during the follow-up. The primary outcome of the study was the presence of a sustained immune humoral response, defined as an anti-SARS-CoV-2 IgG titer >4.99 arbitrary units/mL in at least two consecutive measures. We used generalized lineal models to assess the features associated with this outcome and to assess the effect of the changes in the cytokines and chemokines throughout time on the development of a sustained humoral immune response.ResultsAt baseline the features associated to a sustained immune humoral response were the diagnosis of critical disease, absolute number of lymphocytes, serum IP-10, IL-4, IL-2, regulatory T cells, CD8+ T cells, and positive AC antibodies. Critical illness and the positivity of AC antibodies were associated with a sustained humoral immune response after 3 months, whilst critical illness and serum IL-13 were the explanatory variables after 6 months.ConclusionA sustained immune humoral response is strongly related to critical COVID-19, which is characterized by the presence of AC antibodies, quantitative abnormalities in the T cell compartment, and the serum cytokines and chemokines during acute infection and throughout time.
Journal Article