Design and characterization of refractive secondary optical elements for a point-focus Fresnel lens-based high CPV system

This is the final version of the article. Available from AIP Publishing via the DOI in this record.Point-focus Fresnel lens-based High Concentrator Photovoltaic (HCPV) systems are usually equipped with refractive secondary optical elements (SOE) in order to improve their performance. Two basic SOE designs are optically modeled and simulated in this work: Domed-Kaleidoscope (D-K) with breaking-symmetry top and SILO (SIngle-Lens-Optical element). Wavelength-dependent optical material properties like refractive index and absorption coefficient, as well as the spectral response of a typical triple-junction (TJ) solar cell, are included in the ray tracing simulations. Moreover, using a CPV Solar Simulator "Helios 3198", both HCPV units are experimentally characterized. The acceptance angle characteristics of both HCPV units, obtained through optical simulations and through indoor characterization, are compared. The acceptance angle characteristic is better for the HCPV unit with the D-K SOE both in simulations and in experimental measurements, showing concordance between simulation and experiment. However, simulation results underestimate the experimental ones concerning the acceptance angle, which will be investigated in future works.European Regional Development Fund (ERDF) and Spanish Economy Ministry (ENE2013-45242-R and ENE2016-78251-R); Universidad de Jaén (UJA) and Caja Rural de Jaén (UJA2015/07/01). Financial support provided by the Universidad de Jaén Doctoral School. The authors also thank Lambda Research Corporation for its donation of TracePro optical software

Scutoids are a geometrical solution to three-dimensional packing of epithelia

As animals develop, tissue bending contributes to shape the organs into complex three-dimensional structures. However, the architecture and packing of curved epithelia remains largely unknown. Here we show by means of mathematical modelling that cells in bent epithelia can undergo intercalations along the apico-basal axis. This phenomenon forces cells to have different neighbours in their basal and apical surfaces. As a consequence, epithelial cells adopt a novel shape that we term “scutoid”. The detailed analysis of diverse tissues confirms that generation of apico-basal intercalations between cells is a common feature during morphogenesis. Using biophysical arguments, we propose that scutoids make possible the minimization of the tissue energy and stabilize three-dimensional packing. Hence, we conclude that scutoids are one of nature's solutions to achieve epithelial bending. Our findings pave the way to understand the three-dimensional organization of epithelial organs

Author Correction: Scutoids are a geometrical solution to three-dimensional packing of epithelia.

The original version of this Article contained an error in ref. 39, which incorrectly cited 'Fristrom, D. & Fristrom, J. W. in The Development of Drosophila melanogaster (eds. Bate, M. & Martinez-Arias, A.) II, (Cold spring harbor laboratory press, 1993)'. The correct reference is 'Condic, M.L, Fristrom, D. & Fristrom, J.W. Apical cell shape changes during Drosophila imaginal leg disc elongation: a novel morphogenetic mechanism. Development 111: 23-33 (1991)'. Furthermore, the last sentence of the fourth paragraph of the introduction incorrectly omitted citation of work by Rupprecht et al. The correct citation is given below. These errors have now been corrected in both the PDF and HTML versions of the Article. Rupprecht, J.F., Ong, K.H., Yin, J., Huang, A., Dinh, H.H., Singh, A.P., Zhang, S., Yu, W. & Saunders, T.E. Geometric constraints alter cell arrangements within curved epithelial tissues. Mol. Biol. Cell 28, 3582-3594 (2017)

Treatment with tocilizumab or corticosteroids for COVID-19 patients with hyperinflammatory state: a multicentre cohort study (SAM-COVID-19)

Objectives: The objective of this study was to estimate the association between tocilizumab or corticosteroids and the risk of intubation or death in patients with coronavirus disease 19 (COVID-19) with a hyperinflammatory state according to clinical and laboratory parameters. Methods: A cohort study was performed in 60 Spanish hospitals including 778 patients with COVID-19 and clinical and laboratory data indicative of a hyperinflammatory state. Treatment was mainly with tocilizumab, an intermediate-high dose of corticosteroids (IHDC), a pulse dose of corticosteroids (PDC), combination therapy, or no treatment. Primary outcome was intubation or death; follow-up was 21 days. Propensity score-adjusted estimations using Cox regression (logistic regression if needed) were calculated. Propensity scores were used as confounders, matching variables and for the inverse probability of treatment weights (IPTWs). Results: In all, 88, 117, 78 and 151 patients treated with tocilizumab, IHDC, PDC, and combination therapy, respectively, were compared with 344 untreated patients. The primary endpoint occurred in 10 (11.4%), 27 (23.1%), 12 (15.4%), 40 (25.6%) and 69 (21.1%), respectively. The IPTW-based hazard ratios (odds ratio for combination therapy) for the primary endpoint were 0.32 (95%CI 0.22-0.47; p < 0.001) for tocilizumab, 0.82 (0.71-1.30; p 0.82) for IHDC, 0.61 (0.43-0.86; p 0.006) for PDC, and 1.17 (0.86-1.58; p 0.30) for combination therapy. Other applications of the propensity score provided similar results, but were not significant for PDC. Tocilizumab was also associated with lower hazard of death alone in IPTW analysis (0.07; 0.02-0.17; p < 0.001). Conclusions: Tocilizumab might be useful in COVID-19 patients with a hyperinflammatory state and should be prioritized for randomized trials in this situatio

Variation in male ornaments in two lizard populations with contrasting parasite loads

In the context of the immunocompetence handicap hypothesis, we explored how differences in parasite load affect the way in which sexual ornaments codify information about individual quality. We studied variation in sexual signals in two Iberian populations of the lizard Psammodromus algirus, a species in which sexually active males display a red head coloration. In one population, males were free of tick nymphs, whereas in the other one all males were tick-infested (mean of 12.7 tick nymphs/individual).At the onset of the breeding season, the red-coloured surface was larger in the non-parasitized population than in the parasitized one, whereas the opposite was true for colour saturation. We experimentally simulated a bacterial infection (by intraperitoneal injection of lipopolysaccharide) to examine the effects of immune activation on the expression of this sexual ornament. In the non-parasitized population, our treatment caused a reduction in the red-coloured surface of experimental males, whereas in the parasitized population it caused a decrease in colour saturation. In the parasitized population, males that displayed sexual coloration were larger, and had fewer parasites, than uncoloured ones, and inflammatory response to lipopolysaccharide injection in the palm of the hind paw was negatively correlated with colour saturation, but not with colour extension. Thus, we suggest parasites not only constrained the expression of sexual ornaments, but they also changed the signal properties that conveyed useful information about the quality of their bearers

Nonhistological diagnosis of human cerebral tumors by 1H magnetic resonance spectroscopy and amino acid analysis

We describe a multivariate analysis procedure to classify human cerebral tumors nonhistologically in vitro, combining the use of 1H magnetic resonance spectroscopy (MRS) with automatic amino acid analysis of biopsy extracts. Eighty-one biopsies were obtained surgically and classified histologically in eight classes: high-grade astrocytomas (class 1, n = 19), low-grade astrocytomas (class 2, n = 10), normal brain (class 3, n = 9), medulloblastomas (class 4, n = 4), meningiomas (class 5, n = 18), metastases (class 6, n = 8), neurinomas (class 7, n = 9), and oligodendrogliomas (class 8, n = 4). Perchloric acid extracts were prepared from every biopsy and analyzed by high resolution 1H MRS and automatic amino acid analysis by ionic exchange chromatography. Intensities of 27 resonances and ratios of resonances were measured in the 1H MRS spectra, and 17 amino acid concentrations were determined in the chromatograms. Linear discriminant analysis provided the most adequate combination of these variables for binary classifications of a biopsy between any two possible classes and in multiple choice comparisons, involving the eight possible classes considered. Correct diagnosis was obtained when the class selected by the computer matched the histological diagnosis. In binary comparisons, consideration of the amino acid profile increased the percentage of correct classifications, being always higher than 75% and reaching 100% in many cases. In multilateral comparisons, scores were: high-grade astrocytomas, 80%; low-grade astrocytomas, 74%; normal brain, 100%; medulloblastomas, 100%; meningiomas, 94.5%; metastases, 86%; neurinomas, 100%; and oligodendrogliomas, 75%. These results indicate that statistical multivariate procedures, combining 1H MRS and amino acid analysis of tissue extracts, provide a valuable classifier for the nonhistological diagnosis of biopsies from brain tumors in vitro.Supported in part by grants from the Community of Madrid 08.1/0023/97 and 08.1/0046/98.Peer Reviewe

Double-balloon enteroscopy: a descriptive study of 50 explorations Enteroscopia de doble balón: estudio descriptivo de 50 exploraciones

Aim: to evaluate the utility of double-balloon enteroscopy for small-bowel disease. Design: a prospective study of 50 consecutive enteroscopies performed from December 2004 to July 2005 to analyze diagnoses and treatments. Patients: 44 patients (33 had undergone a previous capsule endoscopy) with indications for obscure digestive hemorrhage, angiodysplasia, Peutz-Jeghers syndrome, ulcer, suspected Crohn's disease, tumors, and refractory celiac disease. Results: we carried out enteroscopy studies in 44 patients by the oral route and, in 6 additional patients, by both the oral and anal routes. We reached the ileon with the oral route in all cases but one (jejunal stenosis), and in 4 cases out of 7 with the anal route, with an average duration of 73 minutes. We found angiodysplasia in 19 cases, as well as NSAID-related enteropathy, Crohn's disease, diverticulosis, and Waldenström's disease. We performed biopsies in 31% of cases with diagnoses of adenocarcinoma, lymphangiectasia secondary to tumor in celiac disease, and Whipple's disease. We treated 19 patients with angiodysplasia (1 to 20 synchronous lesions) with argon, and 4 patients with polyps using polipectomy (sporadic polyps or Peutz-Jeghers syndrome). A retained capsule in one patient with stenosis was removed. Conclusions: double-balloon enteroscopy is a useful and effective technique in the diagnosis and treatment of small intestine diseases, thus complementing capsule endoscopy. More studies are needed to analyze its impact on the management of this condition.<br>Objetivo: valorar la utilidad de la enteroscopia de doble balón en enfermedades de intestino delgado. Diseño: estudio prospectivo descriptivo de 50 enteroscopias consecutivas (diciembre 2004 a julio 2005), analizando diagnóstico y terapéutica. Pacientes: cuarenta y cuatro pacientes (33 con cápsula endoscópica previa) con hemorragia digestiva oculta o lesiones detectadas mediante cápsula (angiodisplasias, pólipos, úlceras, enfermedad de Crohn, celiaca refractaria y tumores). Resultados: se realizó enteroscopia vía oral a 44 pacientes y vía oral más anal a 6. Por vía oral se progresó hasta íleon en todos los casos excepto uno (estenosis yeyunal), por vía anal en 4 de 7 (3 casos con dificultad de paso por Bahuin). La duración media fue 73 minutos. Se detectaron angiodisplasias (19 casos), úlceras en enteropatía por AINE, enfermedad de Crohn, enfermedad de Waldenström, y divertículos. Se realizaron biopsias en yeyuno-íleon en un tercio de los casos (adenocarcinoma, linfangiectasias secundarias a tumor sobre celíaca, enfermedad de Whipple). Se realizó terapéutica con argón a 19 pacientes con angiodisplasias (1 a 20 lesiones), polipectomía a 4 pacientes con pólipos esporádicos o Peutz Jeghers (1 a 15 pólipos) y se extrajo una cápsula endoscópica retenida en una estenosis. Conclusiones: la enteroscopia de doble balón es una técnica útil y eficaz en el diagnóstico y tratamiento de las lesiones del intestino delgado, complementando a la cápsula endoscópica. Hacen falta más estudios para analizar el impacto esperado en el cambio del manejo de estos pacientes