807 resultados para Omega-centauri


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napisał C. Omega [d. i. Celestin Zyblikiewicz]

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Recent geomorphological observations as well as chemical and thermodynamic studies demonstrate that liquid water should be stable today on the Martian surface at some times of the day. In Martian conditions, brines would be particularly more stable than pure water because salts can depress the freezing point and lower the evaporation rate of water. Despite this evidence, no clear spectral signature of liquid has been observed so far by the hyperspectral imaging spectrometers OMEGA and CRISM. However, past spectral analysis lacks a good characterization of brines׳ spectral signatures. This study thus aims to determine how liquid brines can be detected on Mars by spectroscopy. In this way, laboratory experiments were performed for reproducing hydration and dehydration cycles of various brines while measuring their spectral signatures. The resulting spectra first reveal a very similar spectral evolution for the various brine types and pure water, with the main difference observed at the end of the dehydration with the crystallization of various hydrated minerals from brines. The main characteristic of this spectral behavior is an important decoupling between the evolution of albedo and hydration bands depths. During most of the wetting/drying processes, spectra usually display a low albedo associated with shallow water absorption band depths. Strong water absorption band depth and high albedo are respectively only observed when the surface is very wet and when the surface is very dry. These experiments can thus explain why the currently active Martian features attributed to the action of a liquid are only associated with low albedo and very weak spectral signatures. Hydration experiments also reveal that deliquescence occurs easily even at low temperature and moderate soil water vapor pressure and could thus cause seasonal darkening on Mars. These experiments demonstrate that the absence of water absorptions in CRISM in the middle afternoon does not rule out water activity and suggest future spectral investigations to identify water on the Martian surface.

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Purpose It has been shown that lutein and zeaxanthin accumulate in the macula where they enhance contrast sensitivity and may reduce the risk of progression to advanced age-related macular degeneration (AMD). Furthermore, omega-3 long-chain polyunsaturated fatty acids (PUFA) might further reduce this risk. However, controversy exists regarding whether PUFA may reduce the bioavailability of lutein. Methods This was a prospective 12-month, randomized, open label study evaluating the effect of supplementation with lutein, other antioxidants, and minerals on contrast sensitivity (CS) and macular pigment optical density (MPOD) in patients with age-related maculopathy. A total of 79 patients were randomized to either lutein (10 mg) and antioxidant supplement or lutein and antioxidant supplement in combination with PUFA. Patients received supplementation for a period of 6 months and were followed for a total of 12 months. Results Serum lutein and zeaxanthin increased significantly by the first follow-up visit at 1 month, and remained elevated throughout the intervention period of 6 months in the lutein-only group but not in the lutein+PUFA group. Macular pigment optical density and CS increased significantly in the lutein-only group (P < 0.005) but not in the lutein+PUFA group (P = 0.059) compared to baseline. Best-corrected visual acuity remained unchanged during the entire study period in both groups. Conclusions Addition of PUFA may reduce the bioavailability of lutein and therefore lessen the beneficial effect on macular pigment and CS. This needs to be considered when prescribing lutein supplements to patients with low lutein levels. (ClinicalTrials.gov number, NCT00563979.).

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Eight members of a family of Working Kelpies were presented with signs compatible with dermatomyositis. Alopecia, crusts, ulcerations of the skin, depigmentation of nasal planum and lips, onychodystrophy and atrophy of the masticatory muscles were present with varying degree. Histopathology of the skin, but not from muscles was performed in three dogs and confirmed the clinical diagnosis. Different immunomodulating drugs (steroids, cyclosporine, mycophenolate mofetil, pentoxifylline, doxycyline/niacinamid, omega-3 fatty acids and vitamin E) were used with variable success. Dermatomyositis is an immune-mediated disease and a genetic predisposition is known in humans and certain canine breeds, mainly Shetland Sheepdogs and Collies, but also for the Beauceron. The responsible genes have not been identified so far. It is assumed that the Working Kelpie derives from the Collie which could explain a hereditary predisposition in the Kelpie.

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Arachidonic acid (5Z,8Z,11Z,14Z-eicosatetraenoic acid; C20:4) (arachidonate, AA) is a vital polyunsaturated omega-6 fatty acid (PUFA) without its presence the mammalian brain, muscles, and possibly other organs cannot develop or function [1] and [2]. AA fulfils numerous known and possibly yet unknown functions as integral part of mammalian phospholipid membranes and as free AA which also acts as a precursor of a variety of biologically active lipid mediators generally referred to as eicosanoids (e.g., prostaglandins, leukotrienes). A more recent class of eicosanoids is composed of the endogenous cannabinoids (endocannabinoids) 2-arachidonoyl glycerol (2-AG) and arachidonoyl ethanolamide (anandamide, AEA), which act on cannabinoid CB1 and CB2 receptors but also modulate ion channels and nuclear receptors [3] and [4]. In recent years, the role of endocannabinoids as prominent anti-inflammatory and neuromodulatory eicosanoids has been shown by numerous studies [5].

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Conversation is central to the process of organizational learning and change. Drawing on the notion of reflective conversation, we describe an action research project, "learning through listening" in Omega, a residential healthcare organization. In this project, service users, staff, members of management committees, trustees, managers, and central office staff participated in listening to each other and in working together towards building capacity for creating their own vision of how the organization could move into the future, according to its values and ethos. In doing so they developed ways of engaging in reflective conversation that enabled progress towards a strategic direction.

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At the mid-latitudes of Utopia Planitia (UP), Mars, a suite of spatially-associated landforms exhibit geomorphological traits that, on Earth, would be consistent with periglacial processes and the possible freeze-thaw cycling of water. The suite comprises small-sized polygonally-patterned ground, polygon-junction and -margin pits, and scalloped, rimless depressions. Typically, the landforms incise a dark-toned terrain that is thought to be ice-rich. Here, we investigate the dark-toned terrain by using high resolution images from the HiRISE as well as near-infrared spectral-data from the OMEGA and CRISM. The terrain displays erosional characteristics consistent with a sedimentary nature and near-infrared spectra characterised by a blue slope similar to that of weathered basaltic-tephra. We also describe volcanic terrain that is dark-toned and periglacially-modified in the Kamchatka mountain-range of eastern Russia. The terrain is characterised by weathered tephra inter-bedded with snow, ice-wedge polygons and near-surface excess ice. The excess ice forms in the pore space of the tephra as the result of snow-melt infiltration and, subsequently, in-situ freezing. Based on this possible analogue, we construct a three-stage mechanism that explains the possible ice-enrichment of a broad expanse of dark-toned terrain at the mid-latitudes of UP: (1) the dark-toned terrain accumulates and forms via the regional deposition of sediments sourced from explosive volcanism; (2) the volcanic sediments are blanketed by atmospherically-precipitated (H2O) snow, ice or an admixture of the two, either concurrent with the volcanic-events or between discrete events; and, (3) under the influence of high obliquity or explosive volcanism, boundary conditions tolerant of thaw evolve and this, in turn, permits the migration, cycling and eventual formation of excess ice in the volcanic sediments. Over time, and through episodic iterations of this scenario, excess ice forms to decametres of depth. (C) 2015 Elsevier B.V. All rights reserved.

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Making seafood choices isn't easy for consumers who want to minimize exposure to mercury but also take advantage of healthy Omega-3 fatty acids. Rob Mason's research on mercury in various ocean fish and shellfish, and his discussion of what factors are important to consider, helps readers make wise choices.

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The recA gene is essential for SOS response induction, for inducible DNA repair and for homologous recombination in E. coli. The level of recA expression is significant for these functions. A basal level of about 1000 molecules of RecA protein is sufficient for homologous recombination of the cell and is essential for the induction of the SOS response. Based on previous observations, two models regarding the origin of the basal RecA protein were postulated. One was that it comes from the leaky expression of the LexA repressed promoter. The other was that it is from another weak but constitutive promoter. The first part of this thesis is to study these possibilities. An $\Omega$ cartridge containing the transcription terminator of gene 32 of T4 phage was exploited to define a second promoter for recA expression. Insertion of this $\Omega$ cartridge downstream of the known promoter gave rise to only minor expression. Purification and N-terminus sequencing of the RecA protein from the insertion mutant did not support the existence of a second promoter. To determine whether the basal RecA is due to the leaky expression of the known LexA repressed promoter, recA expression of a SOS induction minus strain (basal level expression of recA) was compared with that of a recA promoter down mutation recA1270. The result demonstrated that there is leaky expression from the LexA repressed promoter. All the evidence supports the conclusion that there is only one promoter for both basal and induced expression levels of recA.^ Several translation enhancer sequences which are complementary to different regions of the 16S rRNA were found to exist in recA mRNA. The leader sequence of recA mRNA is highly complementary to a region of the 16S rRNA. Thus it appeared that recA expression could be regulated at post-transcriptional levels. The second part of this thesis is focused on the study of the post-transcriptional control of recA expression. Deletions of the complementary regions were created to examine their effect on recA expression. The results indicated that all of the complementary regions were important for the normal expression of recA and their effects were post-transcriptional. RNA secondary structures of wild type recA mRNA was inspected and a stem-loop structure was revealed. The expression down mutations at codon 10 and 11 were found to stabilize this structure. The conclusions of the second part of this thesis are that there is post-transcriptional control for recA expression and the leader sequence of recA mRNA plays more than one role in the control of recA expression. ^

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delta11B results and deduced pH, pCO2 and omega values obtained for a tropical coral specimen Porites collected in 1998 at Yasawa (16°48'S- 177°27'E) on the western side of the Fiji archipelago, location in the north western part of the Pacific Warm Pool. Such Porites specimen grew during the XXth century (1898-1998). Boron isotopes results allowed the reconstruction of surface ocean acidification in the vincinity of Fiji Islands with strong interdecadal influence of the ENSO at regional scale. pHT calculation parameters (Hönisch et al., 2007): a=0 PER MIL; alpha=0.9804; delta11B=39.5 PER MIL; salinity=35.02; pKB from Dickson (1990). pCO2 and omega calculation parameters: TA= 2350 µM; Ca= 10.2 mM; Dickson et al.(2007); Mucci 1983.

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Ocean acidification leads to changes in marine carbonate chemistry that are predicted to cause a decline in future coral reef calcification. Several laboratory and mesocosm experiments have described calcification responses of species and communities to increasing CO2. The few in situ studies on natural coral reefs that have been carried out to date have shown a direct relationship between aragonite saturation state (Omega arag) and net community calcification (Gnet). However, these studies have been performed over a limited range of Omega arag values, where extrapolation outside the observational range is required to predict future changes in coral reef calcification. We measured extreme diurnal variability in carbonate chemistry within a reef flat in the southern Great Barrier Reef, Australia. Omega arag varied between 1.1 and 6.5, thus exceeding the magnitude of change expected this century in open ocean subtropical/tropical waters. The observed variability comes about through biological activity on the reef, where changes to the carbonate chemistry are enhanced at low tide when reef flat waters are isolated from open ocean water. We define a relationship between net community calcification and Omega arag, using our in situ measurements. We find net community calcification to be linearly related to Omega arag, while temperature and nutrients had no significant effect on Gnet. Using our relationship between Gnet and Omega arag, we predict that net community calcification will decline by 55% of its preindustrial value by the end of the century. It is not known at this stage whether exposure to large variability in carbonate chemistry will make reef flat organisms more or less vulnerable to the non-calcifying physiological effects of increasing ocean CO2 and future laboratory studies will need to incorporate this natural variability to address this question.

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Cuando se habla de alimentación saludable, se aconsejan cuatro comidas diarias y dos colaciones en base a frutas o lácteos. Sin embargo, existe una tendencia a limitar el número de comidas, debido al ritmo de vida que se lleva actualmente y, a su vez,a aumentar el número de ocasiones en el día donde se comen pequeñas cantidades de comidas a intervalos irregulares, especialmente “snacks". Convirtiéndose un componente muy importante de la dieta, siendo fuente de calorías adicionales que podrían o no estar indicados en el plan alimentario adecuado. El problema detona a partir de la última década, ya que ha crecido notablemente, en varios países del mundo (tanto en países desarrollados como en aquellos que se encuentran en vías de desarrollo), la prevalencia de sobrepeso y de obesidad, considerándose, por ello, una epidemia global y siendo la enfermedad crónica no transmisible más prevalente en estos tiempos (Archivos Argentinos de Pediatría, 2005). Reconociéndose como un gran problema de salud pública, según la Organización Mundial de la Salud (OMS), que conlleva a otras enfermedades no transmisibles. Por esto, el consumidor comienza a preocuparse por tener una alimentación saludable y se hace necesario el desarrollo de snacks que se adapten a esta necesidad. El objetivo general de este proyecto es desarrollar galletas saladas tipo snack mejorando sus características nutricionales, rediseñando las formulaciones para que sean atractivas al consumo utilizando las propiedades beneficiosas a la salud del aceite de oliva virgen, por el alto contenido de ácidos grasos monoinsaturados, la buena relación de ácido graso linoleico (omega 6) y el ácido graso linolénico (omega 3), y por el contenido de sustancias antioxidantes. (Alonso, 1993). El desarrollo del producto comenzó con la pre-selección de 9 formulaciones de galletas que coincidieran con las características deseadas, estas fueron sometidas a una evaluación sensorial realizada por 20 evaluadores semi entrenados, resultando elegidas, cinco de ellas. Las formulaciones elegidas fueron sometidas a análisis físico-químicos, a fin de obtener el perfil lipídico de cada una de ellas y su composición centesimal. Una vez obtenida esta información, se efectuó una comparación con snacks que se encontraban el circuito comercial, en los años 2010 y 2014. Por otra parte, se realizó una nueva evaluación sensorial con 100 alumnos de la Facultad de Ciencias Agrarias, a fin de determinar el grado de aceptación. Como conclusión, con respecto al perfil lipídico, se observó un mejoramiento destacado en ambas comparaciones, tanto con respecto a las galletas comerciales de la actualidad, y mucho más notorio, en las del año 2010. Además, se obtuvieron mejores características nutricionales, especialmente con respecto al contenido de sodio y de fibra, en relación al snack presente en el mercado. Desde el punto de vista organoléptico, todas las formulaciones tuvieron buena aceptación.

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The data show the survival data of Atlantic cod larvae from two different stocks, which were measured in two separate experiments in Kristineberg, Sweden in 2013 on the Western Baltic stock and in Tromsö, Norway in 2014 on the Barents Sea stock. Survival was measured as a response to ocean acidification, control tanks were kept at ambient CO2 concentrations. CO2 concentrations and feeding concentrations are also provided.

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This dataset contains raster grids in GeoTIFF format describing the benthic environment of South Georgia. The data include topographic layers that are directly calculated from a bathymetry grid (Slope, Aspect, Roughness, Slope, Terrain Ruggedness Index, Topographic Position Index). A benthic classification of the area is included, based on topographic layers. Also included are sea-bed environmental layers that are interpolated from global three dimensional grids (Alkalinity, Apparent Oxygen Utilisation, Omega Aragonite, Omega Calcite, Dissolved Oxygen, Nitrate, pH, Phosphate, Salinity, Silicate, Temperature, and Total CO2). These layers were used to construct a habitat suitability model for Octocorallia. The geographic extent is 43°57'56.65"W - 33°45'38.19"W and 52°47'29.50"S - 56° 9'11.03"S. The spatial resolution is 150m x 150m (except for benthic classification wihch is 450m x 450m). The map projection is EPSG:3762.