Research relative to angular distribution of snow reflectance/snow cover characterization and microwave emission

Remote sensing has been applied in recent years to monitoring snow cover properties for applications in hydrologic and energy balance modeling. In addition, snow cover has been recently shown to exert a considerable local influence on weather variables. Of particular importance is the potential of sensors to provide data on the physical properties of snow with high spatial and temporal resolution. Visible and near-infrared measurements of upwelling radiance can be used to infer near-surface properties through the calculation of albedo. Microwave signals usually come from deeper within the snow pack and thus provide depth-integrated information, which can be measured through clouds and does not relay on solar illumination.Fundamental studies examining the influence of snow properties on signals from various parts of the electromagnetic spectrum continue in part because of the promise of new remote sensors with higher spectral and spatial accuracy. Information in the visible and near-infrared parts of the spectrum comprise nearly all available data with high spatial resolution. Current passive microwave sensors have poor spatial resolution and the data are problematic where the scenes consist of mixed landscape features, but they offer timely observations that are independent of cloud cover and solar illumination

Histopathological Morphometry of Human Endobronchial Biopsies – a Comparison of Conventional Quantitative Analyses and Stereological Designs

Endobronchial biopsies collected by fiberoptic bronchoscopy have been increasingly used in biomedical research on disease mechanisms and clinical therapy studies of chronic inflammatory airway disorders. Although less invasive techniques are available for the investigation of the inflammatory infiltrate of the bronchial tree, a standardization of their results with respect to the extent or level of the sampled airway proved impracticable. Moreover in a clinical setting the structural alterations of the airway mucosa can only be assessed by histopathological biopsy analysis, which makes this approach indispensable to airway research. More and more quantitative approaches in biopsy studies have been reported. The high variability of their results points out the need for reliable and robust quantitative methods and sampling designs in order to allow for an easier interpretation and corroboration of the outcomes of different studies. It is unclear whether classical 2D approaches and unbiased stereological 3D designs for counting inflammatory cells, measuring area fraction or layer thickness on histological sections are equally well suited for these purposes. The aim of this study was to characterise the agreement between 2D and 3D approaches for inflammatory cell counting by simultaneously applying them on bioptic material. Furthermore, stereological designs were proposed for quantifying the extent of epithelial desquamation and the mean thickness of the reticular basement membrane, and the results were related to previously published data gained by 2D tissue analyses. The hypotheses that the epithelial integrity depends on biopsy size or mean basement membrane thickness were also verified. Biopsies from the segmental bronchi were collected by fiberoptic bronchoscopy in a group of smokers (n=7) and a group of healthy non-smokers (n=7), embedded in paraffin and exhaustively sectioned. Systematic uniform random samples of sections were stained histochemically (PAS) or immunohistochemically for macrophages (CD68) and T-lymphocytes (CD3), respectively. On the same systematic uniform random samples of fields of view, cell numbers per unit volume were assessed using the physical disector and cell and nuclear profiles were counted and related to the subepithelial layer area. To obtain a zero-dimensional index allowing for a direct comparison of the two methods, the CD68+/CD3+ ratio was calculated for each approach. The extent of epithelial desquamation was assessed as area fraction of the basement membrane by counting the intersections of a line grid with the basement membrane on PAS stained sections. On the same sections the arithmetic mean thickness of the reticular basement membrane was estimated using a coherent test system of points and line segments. Counting cell profiles per unit area severely overestimated the number of larger cells (macrophages) relative to smaller cells (T-lymphocytes). Counting of nuclear profiles delivered average values similar to the physical disector but a bias proportional to the magnitude of the CD68+/CD3+ ratios was identified. The extent of epithelial desquamation was similar between the two groups and in accordance with previous studies in healthy volunteers and asthmatics. The lack of a difference between the (non-asthmatic) subjects of this study and published data on asthma patients confirms earlier similar findings. This strengthens the doubt about the morphopathological significance of the epithelial disruption, suggesting an artefactual cause. The arithmetic mean thickness of the reticular basement membrane, an important marker of airway remodelling in biopsy studies of asthma, showed no significant difference between healthy non-smokers and smokers in the small studied groups. The average values were very similar to the results of another published stereological design and to those obtained by image analysis of perpendicular sections. At the same time they were conspicuously lower than the data reported by studies employing direct point-to-point measurements on sections. This underlines the overestimation of the mean thickness introduced by tangential cutting of the basement membrane when relying on 2D measurements of this three-dimensional structure

Mapping Synaptic Pathology within Cerebral Cortical Circuits in Subjects with Schizophrenia

Converging lines of evidence indicate that schizophrenia is characterized by impairments of synaptic machinery within cerebral cortical circuits. Efforts to localize these alterations in brain tissue from subjects with schizophrenia have frequently been limited to the quantification of structures that are non-selectively identified (e.g., dendritic spines labeled in Golgi preparations, axon boutons labeled with synaptophysin), or to quantification of proteins using methods unable to resolve relevant cellular compartments. Multiple label fluorescence confocal microscopy represents a means to circumvent many of these limitations, by concurrently extracting information regarding the number, morphology, and relative protein content of synaptic structures. An important adaptation required for studies of human disease is coupling this approach to stereologic methods for systematic random sampling of relevant brain regions. In this review article we consider the application of multiple label fluorescence confocal microscopy to the mapping of synaptic alterations in subjects with schizophrenia and describe the application of a novel, readily automated, iterative intensity/morphological segmentation algorithm for the extraction of information regarding synaptic structure number, size, and relative protein level from tissue sections obtained using unbiased stereological principles of sampling. In this context, we provide examples of the examination of pre- and post-synaptic structures within excitatory and inhibitory circuits of the cerebral cortex

Different formation routes of pore structure in aluminum powder metallurgy alloy

In powder metallurgy (PM), severe plastic deformation (SPD) is a well-known technological solution to achieve interesting properties. However, the occurrence of pores in the final product may limit these properties. Also, for a given type of microstructure, the stereometric parameters of the pore structures, such as shape (represented by Aspect and Dcircle) and distribution (fshape, and fcircle), decisively affect the final properties. The influence of different processing routes (pressing, sintering and equal channel angular pressing (ECAP)) on pore structures in an aluminum PMalloy is discussed. The nature of porosity, porosity evolution and its behavior is explored. The correlation between pore size and morphology is also considered. The final pore structure parameters (Aspect, Dcircle, fshape, and fcircle) of studied aluminum alloys produced by different processing routes depends on the different formation routes

Computational Approaches and Models for Ovarian Ageing: From 2D to 4D

The theme of the work presented in this multi-disciplinary PhD is the development of new computational tools and techniques to study and understand spatio-temporal follicle growth in neonatal mouse ovaries. The female ovary is endowed at birth with a finite, non-renewable supply of oocytes, each enclosed in a layer of supporting somatic (granulosa) cells to form a quiescent follicle. From birth, a steady trickle of follicles initiate growth to maintain a supply of mature oocytes for regular ovulation. Disruption in the regulation of initiation of follicle growth can result in various pathologies, such as premature ovarian failure and polycystic ovary syndrome. The mechanism of regulation of the initiation of follicle growth remains unclear, but may involve inter-follicle signaling via paracrine growth factors. To investigate this hypothesis, a new technique for quantifying and analyzing spatial distributions of quiescent and growing follicles in the adult human has been developed, as an extension of a novel technique previously developed in neonatal mice in our laboratory. As in the mouse study, we have found evidence that in the human ovary neighbouring quiescent follicles inhibit follicle growth, at a small range. This approach has been further extended to cultured neonatal mouse ovaries, which in vitro lack a systemic blood supply, to investigate the relative contributions of inter-follicle paracrine signaling and endocrine growth factor/nutrient signaling to the regulation of initiation of follicle growth. Accurate counts of the numbers of follicles in ovaries are important for a wide variety of studies of ovarian physiology, including investigating the effects of age, toxins, chemotherapeutics, endocrine disruptors and specific genes (knock out/transgenic studies) on follicle formation, endowment and development. Many published studies use frequent sampling of a small number of ovaries (often as few as three) to obtain estimates of the number of follicles. We have tested the validity of this approach by generating 3D spherical simulated ovaries which contain realistic numbers of follicles at different stages and which are realistically positioned within these ovaries. The number and position of follicles is based on real biological data. This model enables us to rapidly ‘virtually’ section the ovary in silico and obtain computer-generated counts of the numbers of follicles in sections at different frequencies, such as one every fifth section (1/5), 1/20 or 1/50. As we know precisely how many follicles each simulated ovary contains, we can compare the accuracy using different sampling frequencies of varying numbers of ovaries. This has enabled us to demonstrate that the error is smaller when infrequent sampling of a large number of ovaries (≥8) is carried out, and that this actually involves analyzing fewer sections overall. We have gone on to generate simulated ovaries from knockout mice, with more or fewer follicles, and can predict how many ovaries are required to make robust comparisons between knockout and control animals. This has shown that biological variability contributes more to counting error than the method of sampling. These simulated ovaries provide a unique resource to model large studies. Currently follicle counts are obtained by fixing and serially sectioning ovaries, and manually counting the follicles in sections. This is laborious and time-consuming. Faster methods of obtaining follicle estimates are required. With the use of confocal microscopy and immunohistochemistry for an oocyte-specific protein, we were able to establish a protocol that allows us to image and computationally reconstruct a whole neonatal mouse ovary in 3D. Follicle number can be estimated rapidly using a stereologic method. The stereologic technique error was estimated using the simulated ovary model, leading to the conclusion that the method can be safely used to obtain rapid estimates of follicle number. The time required can be further reduced by using image processing to detect the stained follicles on the sections. We have developed an algorithmic technique that can instantaneously identify stained oocytes, count them, and calculate their spatial distribution. A fundamental unanswered question is whether follicles move in the ovary, particularly as they grow. This question has arisen from the observation that small follicles tend to be situated close to the ovarian surface, while large ones are closer to the medulla. This question has implications for interfollicle signaling. We have developed a protocol to image the ovary while in culture using timelapse confocal and live lipid stains to visualize the follicles. Results show that small follicles are not moving significantly over a period of 12h. This project can be extended in the future with the use of transgenic mice for GFP tagging, to accurately monitor changes in structures of interest within cultured ovaries

Exploring CuCrFeVTi system to produce high entropy alloys for high heat flux applications

Cu5Cr35Fe35V20Ti5, Cu10Cr35Fe35V10Ti10, Cu15Cr35Fe35V5Ti10 and Cu20Cr30Fe30V10Ti10 were produced by low-pressure arc-melting to evaluate the feasibility of developing reduced activation high entropy alloys containing copper. The materials present a dendritic microstructure and some Cu and Ti segregation in the as-cast condition, being the Cu5Cr35Fe35V20Ti5 the most homogenous alloy. Copper particles, with a mean size of about 10 nm, are found distributed inside the dendrites. The volume fraction of the copper particles is ~ 7 times higher in the alloy with 5 at.% Cu content that in the alloy with 20 at.%, with values ranging from 22 ± 5 to 3 ± 2 particles/¿m2. Combination of massive Berkovich nanoindentation, statistical analysis and analytical scanning electron microscopy, has been successful for determining the hardness and elastic modulus values of each phase and quantifying their contribution to microhardness values obtained by standard Vickers microindentation.This research has been supported by Agencia Estatal de Investigación (PID2019-105325RB-C33 / AEI / 10.13039/501100011033) and by the Regional Government of Madrid through the program TECHNOFUSIÓN(III)CM (S2018/EMT-4437)

Fabrication and characterization of Cu reinforced with Y-enriched particles following a novel powder metallurgy route

Dispersion strengthened copper alloys have been produced following an innovative powder metallurgy route. Copper and yttrium acetate powders have been mechanically alloyed and posteriorly thermal treated at 923 K for 3 h and 15 h under a hydrogen atmosphere in order to transform the yttrium acetate into Y2O3. Subsequently, the powders were consolidated by hot isostatic pressing. It has been concluded that the duration of the thermal treatment of the powder is a determining factor in the degree of densification of the alloy. The study of the microstructure by Scanning Electron Microscopy and Electron Backscatter Diffraction has revealed the presence of micrometer and submicrometer grains and nanometric Y-O enriched Cu particles embedded in the copper matrix, the mean grain size being smaller for the sample produced from the powder thermal treated for 15 h. Transmission Electron Microscopy investigations concluded that the nanoparticles exhibit a spherical shape with a size up to 25 nm and correspond to monoclinic Y2O3. Annealing twins have been also observed, especially in the material produced from thermal treated powder for longer. The mechanical properties have been inferred from Vickers microhardness measurements and compression tests. Below 473 K the yield strengths of the produced materials are greater than that of pure copper and above 473 K are close to them. From the study of the thermal properties of the densest material it has been found that its thermal conductivity remains nearly constant in the temperature range 300–773 K, and its value is around 85% the thermal conductivity of CuCrZr, the reference material for ITER.The present work has been supported by the Agencia Estatal de Investigación (PID2019-105325RB-C33 / AEI / 10.13039/501100011033) and by the Regional Government of Madrid through the program TECHNOFUSIÓN(III)CM (S2018/EMT-4437). The support of the Regional Government of Madrid through the multi-annual agreement with UC3M ("Excelencia para el Profesorado Universitario"- EPUC3M14) - Fifth regional research plan 2016-2020 is acknowledge