El enfriamiento evaporativo y las pozas de aspersión

La transferencia acoplada de calor y masa en una poza de enfriamiento por aspersión es descrita y calculada a través de las ecuaciones básicas de continuidad y energía. Se establecen las relaciones que describen el movimiento y distribución espacial de gotas, la interacción de éstas con el aire circundante y los coeficientes de transferencia de calor y masa. El sistema álgebro diferencial de ecuaciones modela los campos de temperatura y humedad absoluta, mientras que el campo de velocidad del aire es supuesto constante y se estima a partir de valores obtenidos de literatura. Esta simplificación permite desacoplar, en el cálculo numérico, las variables de velocidad y temperatura. El tratamiento acoplado de estas variables es reportado en otro trabajo de los autores [18]. El modelo obtenido se aplica a una poza circular de enfriamiento por aspersión con viento nulo. Los perfiles de velocidad del aire se proponen invariables y su magnitud y sentido se obtienen de otros trabajos de los autores. La solución simultánea de los campos térmicos y másico se obtiene por medio del método numérico de diferencias finitas. Las ecuaciones de transporte se resuelven usando el método matricial de dirección alternada implícita (ADI). La estabilidad numérica del sistema se alcanza utilizando un factor de amortiguamiento en los coeficientes de la matriz de coeficientes de las ecuaciones discretizadas. Se analizan los resultados que entrega el modelo al variar la viscosidad turbulenta del aire, puesto que influye en los valores de temperatura y humedad del aire, con el correspondiente impacto sobre las características de disipación de la poza

Convección natural asociada a pozas de enfriamiento por aspersión

Las pozas de enfriamiento por aspersión son intercambiadores de calor de tipo evaporativo de contacto directo agua-aire. Así, agua de proceso a alta temperatura se enfrla mediante la aspersión en pequeñas gotas, consiguiendo un aumento considerable del área de transferencia de calor y masa, resultando en una mayor cantidad de energía que las gotas entregan al aire debido al efecto convectivo y al calor latente de vaporización de la masa de agua que se evapora. Las transferencias que se producen alteran la temperatura y humedad del aire circundante, dando origen a fuerzas de empuje que inducen a una convección natural de aire en la poza de aspersión. En otro trabajo de los autores (10) se estudia este efecto, considerando que la convección natural inducida es conocida, con ello se consigue una considerable simplificación del problema planteado. En el presente trabajo no se considera esta simplificación, y el estudio se realiza acoplando numéricamente las ecuaciones de continuidad, transporte de momemtum y la ecuación de Poisson, para el campo dinámico y las ecuaciones de transporte de energfa y transporte de masa para los campos térmico y másico. Ambos campos están ligados principalmente a través de la fuerza de empuje del aire caliente y hlímedo que atraviesa la zona de aspersión, como también de las propiedades del aire. Se presenta el estudio, modelación y resolución numérica de tipo discreta de una poza cilíndrica, atendiendo las ventajas que este tipo de coordenadas presenta para el modelo. El sistema de ecuaciones álgebra diferencia/no lineal resultante, se resuelve por el método numérico de diferencias finitas

Explosive breeding and its consequences for critical adult and embryo behaviors in gliding treefrogs

Anurans exhibit remarkable variation in reproduction, even among closely related species, with consequences for behavior across multiple life stages. Phyllomedusid treefrogs include explosive-breeders and better studied prolonged-breeding species. As adults, the explosive breeders gather rarely, in huge numbers, for intensely concentrated reproductive activity. As embryos, they have faster development, less gelatinous egg clutches, and tougher egg capsules than prolonged breeders, but much lower escape-hatching success in snake attacks. I studied adult and embryo behavior in the explosive-breeding gliding treefrog, Agalychnis spurrelli. First, in Chapter 2 I combined long-term natural history observations and automated acoustic recordings with machine-learning analysis to describe the phenology and environmental predictors of explosive breeding. I found that breeding occurs up to 11 times per year during 1–2-day long reproductive events, from late May to mid-September. Reproductive activity is strongly associated with rainfall over the previous 48 hours, especially afternoon and evening rain. This analysis advances our understanding of explosive-breeding phenology in anurans and highlights the importance of fine-scale changes in environmental conditions for frog reproduction and conservation. In Chapter 3, I tested the long-standing and widely accepted hypothesis that an unusual “egg-kicking” behavior by non-amplexed male A. spurrelli functions as an antagonistic strategy to dislodge and kill competitors’ eggs. I recorded and analyzed videos from breeding aggregations to demonstrate that egg-kicking does not dislodge eggs, rejecting this hypothesis. Instead, I propose this behavior functions as part of an alternative reproductive tactic under highly male-skewed operational sex ratios. In Chapters 4 and 5, I tested two hypotheses about why A. spurrelli embryos have strikingly lower escape-hatching success in snake attacks, compared to the prolonged breeding A. callidryas. In Chapter 4, I assessed a hypothesized sensory constraint, testing if later development of vestibular mechanosensing could constrain the ability of A. spurrelli embryos to sense risk cues. I found that vestibular mechanosensory ability, measured by strength of the vestibulo-occular reflex, strongly predicts hatching responses to physical disturbance in A. spurrelli, as in A. callidryas, and that its developmental timing is similar in both species. This rejects the hypothesized constraint and indicates that some other aspect of their biology causes species differences in escape success. In Chapter 5, I compared the egg-clutch biomechanics of A. spurrelli and A. callidryas and used egg-transplant snake-predation experiments and simulated attacks on de-jellied and control A. spurrelli eggs to test the role of egg and clutch structure in mechanosensory-cued hatching. I found that species differences in clutch structure affect vibration biomechanics and thus the cues available to embryos, and transplantation into A. callidryas clutches improved A. spurrelli’s escape success. Moreover, removing their tough jelly capsule increased hatching attempts and eliminated hatching complications. Together, these experiments show how parentally-produced egg and clutch structures contribute to species differences in embryo behavior and the effectiveness of antipredator defenses. Overall, this research enhances our understanding of how mating systems can influence behavior at multiple life stages and demonstrates the value of integrative and comparative research in elucidating mechanisms that underly functionally important interspecific differences in behavior

Analysis of Plasminogen Genetic Variants in Multiple Sclerosis Patients

Dessa Sadovnick, A.; Alcina, Antonio; Fedetz, María; Matesanz, F.; Vilariño-Güell, Carles; Dessa Sadovnick, A. et. al.Multiple sclerosis (MS) is a prevalent neurological disease of complex etiology. Here, we describe the characterization of a multi-incident MS family that nominated a rare missense variant (p.G420D) in plasminogen (PLG) as a putative genetic risk factor for MS. Genotyping of PLG p.G420D (rs139071351) in 2160 MS patients, and 886 controls from Canada, identified 10 additional probands, two sporadic patients and one control with the variant. Segregation in families harboring the rs139071351 variant, identified p.G420D in 26 out of 30 family members diagnosed with MS, 14 unaffected parents, and 12 out of 30 family members not diagnosed with disease. Despite considerably reduced penetrance, linkage analysis supports cosegregation of PLG p.G420D and disease. Genotyping of PLG p.G420D in 14446 patients, and 8797 controls from Canada, France, Spain, Germany, Belgium, and Austria failed to identify significant association with disease (P = 0.117), despite an overall higher prevalence in patients (OR = 1.32; 95% CI = 0.93–1.87). To assess whether additional rare variants have an effect on MS risk, we sequenced PLG in 293 probands, and genotyped all rare variants in cases and controls. This analysis identified nine rare missense variants, and although three of them were exclusively observed in MS patients, segregation does not support pathogenicity. PLG is a plausible biological candidate for MS owing to its involvement in immune system response, blood-brain barrier permeability, and myelin degradation. Moreover, components of its activation cascade have been shown to present increased activity or expression in MS patients compared to controls; further studies are needed to clarify whether PLG is involved in MS susceptibility.We also thank Généthon, L’Association Française contre les Myopathies (AFM), la Fondation pour l’Aide à la Recherche sur la Sclérose en Plaques (ARSEP), and the Biological Resources Centre (BRC) of The French Multiple Sclerosis Genetics Group (CRB-REFGENSEP). This research was undertaken thanks to funding from the Canada Research Chair [950-228408] and Canada Excellence Research Chair programs [214444], Canadian Institutes of Health Research [MOP-137051], Vancouver Coastal Health Research Institute, the Milan & Maureen Ilich Foundation [11-32095000], and the Vancouver Foundation [ADV14-1597]. Replication studies received funding from the program “Investissements d’avenir” ANR-10-IAIHU-06. Fondo de Investigación Sanitaria (FIS)-Instituto de Salud Carlos III (ISCIII)-Fondos Europeos de Desarrollo Regional (FEDER), Unión Europea [grant numbers P12/00555, PI13/01527, PI13/01466 and PI13/0879 to F.M., A.A. and G.I.] and Junta de Andalucía -FEDER [grant number CTS2704 to F.M.]. B.D. is a Clinical Investigator of the Research Foundation Flanders (FWO-Vlaanderen). A.G. and B.D. are supported by the Research Fund KU Leuven (OT/11/087 and CREA/14/023) and the Research Foundation Flanders (G073415N). A.L.T. reports personal fees from Biogen Idec, Chugai, Medimmune, Teva Innovation, and EMD Serono, and grants and personal fees from Genzyme Sanofi and Roche.Peer reviewe

Historical Review and Update of Surgical Treatment for Corneal Endothelial Diseases

The cornea remains in a state of deturgescence, maintained by endothelial cell Na+/K+ ATPase and by tight junctions between endothelial cells that limit entrance of fluid into the stroma. Fuchs' endothelial corneal dystrophy (FECD) was initially described by Fuchs in 1910 as a combination of epithelial and stromal edema in older patients. It manifests as bilateral, albeit asymmetric, central corneal guttae, corneal edema, and reduced vision. When edema is severe, the corneal epithelium can detach from its basement membrane, creating painful bullae on the anterior surface of the cornea. The course of this dystrophy can be further accelerated after intraocular surgery, specifically cataract extraction. Pseudophakic bullous keratopathy (PBK) is endothelial cell loss caused by surgery in the anterior chamber. If the corneal endothelium is damaged during surgery, the same spectrum of symptoms as found in FECD can develop. In the nineteenth century, penetrating keratoplasty was the only surgical procedure available for isolated endothelial disease. In the 1960s, Dr. José Barraquer described a method of endothelial keratoplasty using an anterior approach via laser-assisted in situ keratomileusis (LASIK) flap. In 1999, Melles and colleague described their technique of posterior lamellar keratoplasty. Later, Melles et al. started to change host dissection using simple "descemetorhexis" in a procedure known as Descemet's stripping endothelial keratoplasty. Following the widespread adoption of Descemet's stripping automated endothelial keratoplasty, the Melles group revisited selective Descemet's membrane transplantation and reported the results of a new procedure, Descemet's membrane endothelial keratoplasty (DMEK). Recently, some eye banks have experimented with the preparation of DMEK/Descemet's membrane automated endothelial keratoplasty donor tissue that may help the surgeon avoid the risk of tissue loss during the stromal separation step. Recently, the authors described a new bimanual technique for insertion and positioning of endothelium-Descemet membrane grafts in DMEK

Outcomes of Cystoid Macular Edema Following Descemet's Membrane Endothelial Keratoplasty in a Referral Center for Keratoplasty in Spain: Retrospective Study

The aim of this study was to analyze the outcomes of eyes with visually significant cystoid macular œdema (vs-CMO) after Descemet membrane endothelial keratoplasty (DMEK) in a referral center for keratoplasty in Spain. We conducted a retrospective, single-surgeon case series of eyes that developed post-DMEK vs-CMO performed between January 2011 and December 2020. Data collected included: indication for DMEK; biometric data; ocular comorbidities; past medical history; time to detection of vs-CMO after DMEK (T, weeks); best-corrected visual acuity (BCVA, logMAR) and central retinal thickness (CRT, µm) at diagnosis of vs-CMO, after resolution of CMO, and at last follow-up; and management strategy. Main outcomes analyzed were incidence of vs-CMO, improvement in BCVA and CRT after treatment of vs-CMO. Of 291 consecutive DMEK surgeries, 14 eyes of 13 patients (4.8%) developed vs-CMO. Five patients (38.5%) had history of CMO, and 28.6% of eyes had ophthalmic comorbidities. Median (P25-P75) T was 4 (3-10) weeks. Treatment success was observed in 12/13 eyes (92.3%), two of which required second-line treatment. In successful cases (median time-to-resolution 3.0 (2.0-3.5) months), median BCVA improved from 0.60 (0.40-0.80) logMAR to 0.30 (0.15-0.40) logMAR (p = 0.002) after treatment, and median CRT improved from 582.5 (400.0-655.0) µm to 278.0 (258.0-294.0) µm (p = 0.005). In our study, we found a 4.8% rate of post-DMEK vs-CMO, with most cases occurring in the first 3 months after surgery. Good functional and anatomical outcomes are expected in most eyes, without treatment-related complications or implications in graft outcomes. Additional studies are encouraged to determine a standardized protocol for post-DMEK vs-CMO.info:eu-repo/semantics/publishedVersio

Carbon dioxide rebreathing in non-invasive ventilation. Analysis of masks, expiratory ports and ventilatory modes

Background and Aim. Carbon dioxide (CO2) rebreathing is a complication of non-invasive ventilation (NIV). Our objectives were to evaluate the ability of masks with exhaust vents (EV) to avoid rebreathing while using positive pressure (PP) NIV with different levels of expiratory pressure (EPAP). Concerning volume-cycled NIV, we aimed to determine whether cylindrical spacers located in the circuit generate rebreathing. Materials and methods. 5 healthy volunteers were evaluated. Bi-level PP was used with 3 nasal and 2 facial masks with and without EV. Spacers of increasing volume attached to nasal hermetic masks were evaluated with volume NIV. Inspired CO2 fraction was analyzed. Results. Rebreathing was zero with all nasal masks and EPAP levels. Using facial masks 1 volunteer showed rebreathing. There was no rebreathing while using all the spacers. Conclusions. In healthy volunteers, nasal and facial masks with EV prevent rebreathing. In addition, the use of spacers did not generate this undesirable phenomenon

Primary alveolar hypoventilation and XXXXY chromosopathy

The association of primary alveolar hypoventilation (PAH) and chromosomic diseases has not been described previously. A 19 year-old man with Fraccaro’s syndrome (XXXXY karyotype) was admitted to evaluate chronic hypercapnic respiratory failure, pulmonary arterial hypertension and cor pulmonale. PAH was diagnosed. As effective treatment, such as non-invasive positive pressure ventilation (NIPPV), is available for this disorder we should intensify the search for PAH in patients with chromosome disease

How to bring out pre-service teachers’ previous experiences and beliefs? Teaching practices from the realistic model

[EN] Various teaching practices are presented to bring out pre-service teachers’ previous experiences and beliefs about the teaching and disciplinary knowledge required to be a teacher. These practices were introduced in subjects in social science education, mathematics education, teaching self-expression through movement and the practical training sessions of the bachelor’s degrees in pre-school and primary school teaching of the University of Girona. The teaching practices were planned and organised based on the teaching staff’s realistic training perspective. This view assumes that teacher training should integrate personal experiences, through reflection, with classroom practice and theoretical knowledge. The starting point is awareness of previous experiences and beliefs. These, if not adequately considered and dealt with, can be an obstacle to the acquisition of new knowledge.The tools and strategies used are role play, open-ended questions, introspective activities based on movement and image analogy. Analysis of the practices reveals how pre-service teachers are becoming aware of their previous experiences and beliefs, and how these can influence their professional identity. It is concluded that these aspects, which are usually deep-rooted, should be reconstructed through reflective cycles during initial teacher training[ES] Se presentan diversas prácticas docentes para hacer emerger las experiencias previas y creencias de los futuros maestros sobre los conocimientos didácticos y disciplinares necesarios para el oficio de enseñar. Estas prácticas se han llevado a cabo en asignaturas de Didáctica de las Sociales, Didáctica de las Matemáticas, Didáctica de la Expresión Corporal y el Prácticum de los Grados de Maestro de Educación Infantil y Primaria de la Universidad de Girona.Las prácticas docentes se han planificado y gestionado a partir de la perspectiva realista de formación del profesorado. Esta perspectiva asume que la formación de maestros debe garantizar la integración de las experiencias personales en la práctica de aula y los conocimientos teóricos, y ello a través de la reflexión. Desde esta perspectiva, el punto de partida es la toma de consciencia de las experiencias previas y creencias, ya que si no se consideran y gestionan adecuadamente pueden ser un obstáculo para la adquisición de nuevos conocimientos.Las herramientas y estrategias usadas son un juego de rol, preguntas abiertas, actividades introspectivas basadas en el movimiento y la analogía con imágenes. El análisis de las prácticas ha puesto de manifiesto cómo los futuros maestros van tomando consciencia de sus experiencias previas y creencias, y cómo éstas pueden influir en su identidad profesional. Se concluye que estos aspectos, que suelen estar muy arraigados, deben ser tratados a través de ciclos reflexivos durante la formación inicial de maestros para favorecer su reconstrucción.Alsina, A.; Batllori, R.; Falgás, M.; Güell, R.; Vidal, I. (2016). ¿Cómo hacer emerger las experiencias previas y creencias de los futuros maestros? Prácticas docentes desde el modelo realista. REDU. Revista de Docencia Universitaria. 14(2):11-36. doi:10.4995/redu.2016.5672.SWORD113614