A phenomenological-based dynamic model for a polymer electrolyte membrane fuel-cell humidifier assembly

This paper presents the deduction of a phenomenological-based semi-physical model (PBSM) for the gas humidification in a fuel-cell assembly. Unlike previously published models, the one proposed here includes the momentum transfer effects and their influences over simultaneous heat and mass transfers occurring into the process as a whole. These effects strongly affect the model precision due to the compressible characteristics of the air. High sensitivity of gas properties regarding changes in both pressure and temperature are also included by modelling the gas as a compressible fluid. The model reproduces the air–water vapour mixture behaviour from the compressor discharge to the fuel-cell inlet port. Since the air humidity and temperature conditions must be maintained at their set-points to guarantee an optimal fuel-cell performance, a model such as the one presented here can be used for designing any model-based control strategy towards achieving desirable operative conditions taking also into account the operational context of the considered assembly. The comparative assessment done with experimental data from a real test bench has shown the effectiveness of the proposed model in accurately reproduce the behaviour of such complex systems.Peer ReviewedPostprint (published version

Parasitic castration in slipper limpets infested by the symbiotic crab Calyptraeotheres garthi

Two ill-explored hypotheses might explain host castration by parasitic pea crabs. The ‘energy drain’ hypothesis states that castration is caused by host-derived nutrient consumption of parasites that ultimately diminishes host-energy intake. The ‘steric interference’ hypothesis states that castration occurs when parasites physically inhibit host reproduction. This study evaluated whether Calyptraeotheres garthi, a pea crab from the southwestern Atlantic, is a parasitic castrator and explored whether the two hypotheses above explain castration in the limpet Crepidula cachimilla. None of three studied limpet species brooded embryos during the reproductive season when infested by mature female pea crabs. Also, limpets of C. cachimilla infested by C. garthi did not reproduce during a 90-day experimental period while crab-free limpets did spawn embryos during this period. Limpets resumed reproduction soon after pea crabs were experimentally removed from their brooding chamber. Thus, C. garthi does castrate limpets, and castration is reversible. Pea crabs ‘steal’ food from limpets, and infested limpets did not modify their feeding behavior to counteract nutrient loss. Thus, infested limpets are expected to ingest less food which provides partial support for the ‘energy drain’ hypothesis. However, the limpet’s body condition increased or was not affected by pea crabs during the breeding season which argues against the same hypothesis. Furthermore, that limpets promptly recovered reproductive activity once pea crabs were experimentally removed, that castration was not induced by the smallest pea crabs in the population (that fill only partially the brooding chamber), and that parasitized limpets did exhibit fully mature ovaries, support the ‘steric interference’ hypothesis explaining parasitic castration.Fil: Ocampo, Emiliano Hernan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Nuñez, Jesus Dario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Cledón, Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Baeza, J. Antonio. Universidad Católica del Norte. Coquimbo; Chile. Smithsonian Marine Station at Fort Pierce; Estados Unido

Cuantización por integral de camino de la teoría de dinámica de formas en 2+1 dimensiones

En este trabajo se calcula la integral de camino en un espacio de fase reducido, para la teoría de Dinámica de Formas en el toro en 2 + 1 dimensiones. Para lo cual, primero se realiza una revisión del método de mejor apareamiento y del procedimiento de intercambio de simetrías, para luego construir la teoría de Dinámica de Formas a partir de la formulación ADM de la Relatividad General. Se muestra que, la integral de camino en el espacio de fase reducido para la teoría de Dinámica de Formas, concuerda con los resultados reportados para la formulación ADM

Impact on reproductive performance and body condition in a small limpet parasitized by a large castrator pea crab

Parasitic castrators utilize the energy reserves that the host allocates on reproduction resulting in sterilization of the host. However, whether other processes (e.g., growth) are also impaired depends on the balance between the castrator's energy requirements and the available resources that the castrated host does not use in reproduction. We investigated whether the castrator pea crab Calytraeotheres garthi alters body condition, reproductive performance, and occurrence of copulation in its limpet host Bostrycapulus odites. For this purpose, we examined the anatomy of the ovary, the seminal receptacles, and the body condition of parasitized and unparasitized limpets. The histology of the female gonad of parasitized limpets revealed the ovarian tubules are smaller and characterized by a greater proportion of intertubular and intratubular free space compared with non-parasitized individuals. The body condition of female limpets from all sizes (during summer) and those larger than ~16 mm (during spring and autumn) were impacted by the pea crab. These results are in contrast to that previously reported in the comparatively larger limpet species Crepidula cachimilla, in which the same pea crab species does not alter or even increase the host body weight. We concluded this pea crab species could drastically impair its host's reproduction and body condition although deleterious effects are species-specific and likely depend on limpet body size. The histology of seminal receptacles revealed an uncommon disposition of spermatozoa (i.e., excessive debris and acrosomes detached from epithelium) in seminal receptacles of some parasitized limpets. However, this analysis failed to determine whether sperm derived from present matings or previous pea crab infection. Further studies are needed to address whether pea crabs interfere with the mating behavior of limpets and if the alterations in sperm disposition are a consequence of castration.Fil: Ocampo, Emiliano Hernan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Pérez García, Macarena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Nuñez, Jesus Dario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Luppi, Tomas Atilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentin

Genetic and morpho-physiological differentiation in a limpet population across an intertidal gradient

Marine organism adaptive capacity to different environmental conditions is a research priority to understand what conditions are important in structuring the spatial distribution of natural populations. In this context, this study evaluates whether potential differences in Siphonaria lessonii morphology (size and shell shape) and physiology (water loss regulation) at different shore heights are linked to genetically distinguishable individuals. To achieve this goal, we compared size-frequency distribution, morphometric, and genetic data (ISSR-PCR technique) of S. lessonii from the upper, middle and lower shore. We complemented these field samplings with laboratory experiments on water loss and mortality. Genetic analysis showed different genetic composition for individuals from the upper and lower shore. This pattern was accompanied by morpho-physiological variations: the upper shore had fewer small limpets, lower shell shape dispersion (with a morphotype characterized by a higher shell), and less water loss and mortality related to air exposure than the lower shore. The results reported herein support the idea that the extreme and unpredictable conditions of the upper shore may impose strong selection pressure on its inhabitants, leading to considerable morpho-physiological differentiation consistent with different genetic composition. This probably plays an important role in structuring the spatial distribution of natural S. lessonii populations with a possible effect on size-structure distribution.Fil: Nuñez, Jesus Dario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Fernandez Iriarte, Pedro Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Ocampo, Emiliano Hernan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Madrid, Enrique. Universidad Nacional de Mar del Plata; ArgentinaFil: Cledón, Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentin

Antiviral RNA silencing suppression activity of \u3ci\u3eTomato spotted wilt virus\u3c/i\u3e NSs protein

In addition to regulating gene expression, RNA silencing is an essential antiviral defense system in plants. Triggered by double-stranded RNA, silencing results in degradation or translational repression of target transcripts. Viruses are inducers and targets of RNA silencing. To condition susceptibility, most plant viruses encode silencing suppressors that interfere with this process, such as the Tomato spotted wilt virus (TSWV) NSs protein. The mechanism by which NSs suppresses RNA silencing and its role in viral infection and movement remain to be determined. We cloned NSs from the Hawaii isolate of TSWV and using two independent assays show for the first time that this protein restored pathogenicity and supported the formation of local infection foci by suppressor-deficient Turnip mosaic virus and Turnip crinkle virus. Demonstrating the suppression of RNA silencing directed against heterologous viruses establishes the foundation to determine the means used by NSs to block this antiviral process

Phylogeny, phylogeography, and systematics of the American pea crab genus Calyptraeotheres Campos, 1990, inferred from molecular markers

We used mitochondrial cytochrome oxidase I (COI) and the large ribosomal subunit (16S) genes to establish evolutionary relationships amongst species of Calyptraeotheres, evaluate their usefulness as DNA-barcoding genes, and assess molecular diversity at the population level within Calyptraeotheres garthi. Bayesian, maximum likelihood, and maximum parsimony phylogenies confirmed the monophyly of Calyptraeotheres, showing that the ancestor of C. garthi, Calyptraeotheres hernandezi, and Calyptraeotheres granti radiated after the formation of the Panamanian isthmus. This finding contradicts the austral/tropical hypothesis previously proposed based on morphological data. The COI and 16S distance matrices supported separation of species as well as the genera, and corroborated that DNA barcoding is a useful tool and complements the classical taxonomy in Pinnotheridae. Phylogenetic and genetic distance analyses suggested that C. hernandezi is a junior synonym of C. garthi. Finally, C. garthi did not show a population structure across its distribution range, and showed a pattern consistent with a recent population expansion event that began 230–300 Kya.Fil: Ocampo, Emiliano Hernan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Robles, Rafael. Universidade de Sao Paulo; BrasilFil: Terossi, Mariana. Universidade de Sao Paulo; BrasilFil: Nuñez, Jesus Dario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Cledón, Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Mantelatto, Fernando L.. Universidade de Sao Paulo; Brasi

Estudio de vida útil microbiológica y sensorial de leche fluida envasada y pasteurizada para producción en agricultura familiar

En Argentina se encuentra prohibida la venta de leche sin pasteurizar, aunque esta práctica se registra en forma habitual en la mayoría de las cuencas lácteas del país siendo sostenida, en parte, por la falta de tecnología adecuada y validada para pequeñas escalas, pero también por la existencia de un segmento que demanda el producto debido a su costo/calidad. Como alternativa novedosa, se diseñó y construyó un equipo para envasar y pasteurizar la leche dentro del envase.Fil: Soteras, Trinidad. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto Tecnología de Alimentos; Argentina.Fil: Palladino, Pablo Martin. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto Tecnología de Alimentos; Argentina.Fil: Justianovich, Sergio Hernan. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto De Investigación y Desarrollo Tecnológico para la Agricultura Familiar (IPAF). Región Pampeana; Argentina.Fil: Ocampo, Fernando David. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto De Investigación y Desarrollo Tecnológico para la Agricultura Familiar (IPAF). Región Pampeana; Argentina.Fil: Ormando, Paula. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto Tecnología de Alimentos; Argentina.Fil: Denoya, Gabriela Inés. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto Tecnología de Alimentos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Evaluación del riesgo de infección por COVID-19 en el Departamento del Valle del Cauca mediante una herramienta TIC

Introducción: The use of technology in the health area is applied through telemedicine and the use of applications for many activities. In our case in risk detection and patient prioritization to COVID-19. Objective: Document the experience in the mobile application use "VALLE CORONA" to COVID-19 and risk stratification. Methods: It is an operational and observational research. A mobile application was designed with 14 questions that were established according to the evidence and recommendations of experts and international institutions and the Colombian National Institute of Health. An algorithm was developed to classify the risk and thus establish possible cases or suspected cases. The risk was established according to the traffic light. Green: Low risk of being infected by SARS COV2, orange: intermediate risk, red: high risk of being infected. Results: The app was used by 3,165 people, 1,893 men and 1,273 women, median age of 37.38 years; 2,026 users between 25-50 years. Algorithm classification was: GREEN: 2,761 cases. RED: 270 cases. >60 years were 23 users and in <60 years were 247. ORANGE: 134 cases >60 years were 11 users and for <60 years 123 cases. Conclusions: The mobile application for the control of a pandemic at the local level is real, economic and has an impact on the follow-up of cases and prioritization of them, in addition to generating an articulation with the different institutions with a cross-sectoral approach; highlighting the success of the mobilization of experts in epidemiology.Introducción: La utilización de la tecnología en el área de la salud es aplicada mediante la telemedicina y utilización de aplicaciones para diversas actividades. En nuestro caso para la detección del riesgo y priorización de pacientes para intervención. Objetivo: Documentar la experiencia en el uso de una aplicación móvil “VALLE CORONA” para COVID-19 y la estratificación del riesgo. Métodos: Es una Investigación operativa y observacional. Se diseño una aplicación con 14 preguntas que se establecieron de acuerdo a la evidencia y recomendaciones de expertos e instituciones internacionales y del Instituto Nacional de Salud colombiano. Se elaboró un algoritmo para clasificar el riesgo y así establecer posibles casos o casos sospechosos. El riesgo se estableció según el semáforo. Verde: Bajo riesgo de cursar con infección por SARS COV2, naranja: riesgo intermedio, rojo: alto riesgo de cursar con la infección. Resultados: La aplicación fue utilizada por 3,165 usuarios, 1,893 hombres y 1,273 mujeres, mediana de edad: 37.38 años; 2,026 usuarios entre 25-50 años. Clasificación del algoritmo: VERDE: 2,761 casos. ROJO:  270 casos. >60 años fueron 23 usuarios y en <60 años fueron 247. NARANJA: 134 casos > 60 años fueron 11 usuarios y para los <60 años 123 casos. Conclusiones: La aplicación móvil para el control de una pandemia a nivel local es real, económica y tiene impacto para el seguimiento de casos y priorización de ellos, además que genera una articulación con las diferentes instituciones con enfoque transectorial e intersectorial; destacándose el éxito de la movilización de los expertos en epidemiologia

Fragmentation of Andes-to-Amazon connectivity by hydropower dams

Andes-to-Amazon river connectivity controls numerous natural and human systems in the greater Amazon. However, it is being rapidly altered by a wave of new hydropower development, the impacts of which have been previously underestimated. We document 142 dams existing or under construction and 160 proposed dams for rivers draining the Andean headwaters of the Amazon. Existing dams have fragmented the tributary networks of six of eight major Andean Amazon river basins. Proposed dams could result in significant losses in river connectivity in river mainstems of five of eight major systems—the Napo, Marañón, Ucayali, Beni, and Mamoré. With a newly reported 671 freshwater fish species inhabiting the Andean headwaters of the Amazon (>500 m), dams threaten previously unrecognized biodiversity, particularly among endemic and migratory species. Because Andean rivers contribute most of the sediment in the mainstem Amazon, losses in river connectivity translate to drastic alteration of river channel and floodplain geomorphology and associated ecosystem services