2,782 research outputs found

    Chemical evolution of the bulge of M31: predictions about abundance ratios

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    We aim at reproducing the chemical evolution of the bulge of M31 by means of a detailed chemical evolution model, including radial gas flows coming from the disk. We study the impact of the initial mass function, the star formation rate and the time scale for bulge formation on the metallicity distribution function of stars. We compute several models of chemical evolution using the metallicity distribution of dwarf stars as an observational constraint for the bulge of M31. Then, by means of the model which best reproduces the metallicity distribution function, we predict the [X/Fe] vs. [Fe/H] relations for several chemical elements (O, Mg, Si, Ca, C, N). Our best model for the bulge of M31 is obtained by means of a robust statistical method and assumes a Salpeter initial mass function, a Schmidt-Kennicutt law for star formation with an exponent k=1.5, an efficiency of star formation of 15±0.27Gyr1\sim 15\pm 0.27\, Gyr^{-1}, and an infall timescale of 0.10±0.03\sim 0.10\pm 0.03Gyr. Our results suggest that the bulge of M31 formed very quickly by means of an intense star formation rate and an initial mass function flatter than in the solar vicinity but similar to that inferred for the Milky Way bulge. The [α\alpha/Fe] ratios in the stars of the bulge of M31 should be high for most of the [Fe/H] range, as is observed in the Milky Way bulge. These predictions await future data to be proven.Comment: Accepted for publication by MNRA

    A first-order stabilization-free Virtual Element Method

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    In this paper, we introduce a new Virtual Element Method (VEM) not requiring any stabilization term based on the usual enhanced first-order VEM space. The new method relies on a modified formulation of the discrete diffusion operator that ensures stability preserving all the properties of the differential operator.(c) 2023 Elsevier Ltd. All rights reserved

    Poredbene hematološke i biokemijske analize divovske amazonske kornjače uzgajane pod lošim i normalnim hranidbenim uvjetima

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    Besides indicating the baseline values of the species, blood parameter assessments of chelonian may also be used as quick tools for diagnosing health status. An investigation was carried out to assess and compare red blood cells parameters, white blood cell (WBC) and total thrombocyte counts and certain blood biochemical parameters for freshwater turtles, Podocnemis expansa Schweigger, 1812 (Pelomedusidae) reared on normal (control group) and poor nutrition (malnourished group). For the malnourished turtles, a signififi cant decrease (P<0.05) in red blood cell counts was found, including hematocrit, plasma glucose, plasma total protein, cholesterol and urea levels, as well as WBC counts, azurophils and heterophils. Malnutrition did not alter the hemostasis, but caused severe normocytic-hypocromic anemia and marked immune depression, which were diagnosed here. This study was the fifi rst to characterize the physiological and immune status of giant turtles from the Amazon under adverse nutritional conditions.Osim za utvrđivanje osnovnih vrijednosti osebujnih za vrstu, pretraživanje krvnih pokazatelja može u kornjača biti rabljeno za brzo određivanje njihova zdravstvenoga stanja. Istraživanje je poduzeto da se odrede i usporede pokazatelji crvenih krvnih stanica, bijelih krvnih stanica, ukupnog broja trombocita i neki biokemijski pokazatelji za slatkovodne kornjače Podocnemis expansa Schweigger, 1812 (Pelomedusidae) uzgajane u normalnim (kontrolna skupina) i lošim hranidbenim uvjetima (pokusna skupina). U kornjača uzgajanih u lošim uvjetima ustanovljen je značajno smanjen (P<0,05) broj crvenih krvnih stanica kao i smanjene vrijednosti hematokrita, razine glukoze u plazmi, razine ukupnih proteina plazme, kolesterola i mokraćevine te broj bijelih krvnih stanica, azurofila i heterofila. Loša hranidba nije utjecala na hemostazu, ali je prouzročila tešku normocitnu hipokromnu anemiju i znatnu imunodepresiju. Ovo je prvo istraživanje u kojem je prikazan fiziološki i imunološki status divovske kornjače iz Amazone, držane u nepovoljnim hranidbenim uvjetima

    Efeito de fitase sobre o desempenho zootécnico de frangos de corte consumindo dietas com maior ou menor teor de fitato.

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    Alimentos alternativos estão sendo estudados com o intuito de buscar matérias-primas em substituição ao milho e farelo de soja, os quais estão escassos e com um alto valor no mercado. Destes, uma opção é o farelo de trigo que pode ser incluído na dieta de aves em pequenas proporções, em virtude do alto teor de fibra e outros fatores antinutricionais. Para minimizar estes fatores pode-se optar pela suplementação de fitase exógena para aumentar a degradação do fitato do farelo de trigo, sendo que esta melhoria permite que o alimento seja usado em níveis mais elevados, fornecendo proporções consideráveis de fósforo e outros minerais, reduzindo os custos com alimentação e a poluição ambiental (POURREZA & CLASSEN, 2001; CLASSEN & BEDFORD, 2001; KERR et al., 2010). Com isso, o objetivo deste trabalho foi avaliar o efeito do farelo de trigo e fitase sobre os parâmetros de desempenho zootécnico de frangos de corte de um a 32 dias de idade

    Abyssal plain faunal carbon flows remain depressed 26 years after a simulated deep-sea mining disturbance

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    Future deep-sea mining for polymetallic nodules in abyssal plains will negatively impact the benthic ecosystem, but it is largely unclear whether this ecosystem will be able to recover from mining disturbance and if so, to what extent and at what timescale. During the “DISturbance and reCOLonization” (DISCOL) experiment, a total of 22% of the seafloor within a 10.8 km2 circular area of the nodulerich seafloor in the Peru Basin (SE Pacific) was ploughed in 1989 to bury nodules and mix the surface sediment. This area was revisited 0.1, 0.5, 3, 7, and 26 years after the disturbance to assess macrofauna, invertebrate megafauna and fish density and diversity. We used this unique abyssal faunal time series to develop carbon-based food web models for each point in the time series using the linear inverse modeling approach for sediments subjected to two disturbance levels: (1) outside the plough tracks; not directly disturbed by plough, but probably suffered from additional sedimentation; and (2) inside the plough tracks. Total faunal carbon stock was always higher outside plough tracks compared with inside plough tracks. After 26 years, the carbon stock inside the plough tracks was 54% of the carbon stock outside plough tracks. Deposit feeders were least affected by the disturbance, with modeled respiration, external predation, and excretion rates being reduced by only 2.6% inside plough tracks compared with outside plough tracks after 26 years. In contrast, the respiration rate of filter and suspension feeders was 79.5% lower in the plough tracks after 26 years. The “total system throughput” (T ..), i.e., the total sum of modeled carbon flows in the food web, was higher throughout the time series outside plough tracks compared with the corresponding inside plough tracks area and was lowest inside plough tracks directly after the disturbance (8.63 103 1.58 105 mmol Cm2 d1). Even 26 years after the DISCOL disturbance, the discrepancy of T .. between outside and inside plough tracks was still 56 %. Hence, C cycling within the faunal compartments of an abyssal plain ecosystem remains reduced 26 years after physical disturbance, and a longer period is required for the system to recover from such a small-scale sediment disturbance experiment.publishe

    Risk factors for pre-clinical atherosclerosis in adolescents with type 1 diabetes

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    Aims: To assess whether, besides "traditional" risk factors, overall oxidative stress, oxidized lipoproteins, and glycemic variability are associated with early macro-vascular damage in type 1 diabetes (T1D). Methods: In 267 children/adolescents with T1D (130 girls, age 9.1-23.0 years) we evaluated: derivatives of reactive oxygen metabolites [d-ROMs], serum total antioxidant capacity [TAC] and oxidized LDL-cholesterol [oxLDL]; markers of early vascular damage (Lipoprotein-associated phospholipase A2 [Lp-PLA2], z-score of carotid intima-media thickness [z-cIMT] and carotid-femoral pulse wave velocity [z-PWV]); CGM metrics of four weeks preceding the visit, central systolic/diastolic blood pressures (cSBP/cDBP), and HbA1c, z-score of BP (z-SBP/z-DBP) and circulating lipids longitudinally collected since T1D onset.. Three general linear models were built with z-cIMT, z-PWV adjusted for current cDBP, and Lp-PLA2 as independent variables. Results: The z-cIMT was associated with male gender (B = 0.491, η2 = 0.029, p = 0.005), cSBP (B = 0.023, η2 = 0.026, p = 0.008) and oxLDL (B = 0.022, η2 = 0.022, p = 0.014). The z-PWV was associated with diabetes duration (B = 0.054, η2 = 0.024, p = 0.016), daily insulin dose (B = 0.52, η2 = 0.018, p = 0.045), longitudinal z-SBP (B = 0.18, η2 = 0.018, p = 0.045) and dROMs (B = 0.003, η2 = 0.037, p = 0.004). Lp-PLA2 was associated with age (B = 0.221, η2 = 0.079, p = 3*10-6), oxLDL (B = 0.081, η2 = 0.050, p = 2*10-4), longitudinal LDL-cholesterol (B = 0.031, η2 = 0.043, p = 0.001) and male gender (B = -1.62, η2 = 0.10, p = 1.3*107). Conclusions: Oxidative stress, male gender, insulin dose, diabetes duration and longitudinal lipids and blood pressure, contributed to the variance of early vascular damage in young patients with T1D

    Evaluation of the productive and vegetative aspects of the cultivar 'Imperial Gala' apple tree with EM-9 interstem in different lengths.

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    The obtaining of a compact plant, with less vigor and high productivity, equivalent to a conventional plant, constitutes a strong tendency in the current horticulture, aiming at a raising of the fruit production at the same planted area. One of the techniques that have had success nowadays is the interstem use. This study was developed in a commercial orchard of Randon Agro Silvo Pastoril S.A. (RASIP), located in the Rio Grande do Sul state, Brazil. The purpose of this work was to evaluate the vegetative and productive development of apple trees of 'Imperial Gala' with different lengths of EM-9 interstem. The treatments consisted of five interstem lengths: 10, 15, 20, 25, 30 cm. In the seventh year of implantation the following parameters were evaluated: the height of the plant, the diameter of the 'Imperial Gala' 5 cm above the second graft point, the volume of the tree-head (height, width and length), the number of bud per branch, and the number of fruits per lineal centimeter of branch. Through this study it could be concluded that the greater interstem (30 cm) presented better indices with relation of vigor control. However, the number of fruits per lineal centimeter of branch with the interstem of 10 cm offered only significant superiority, when compared with the interstem of 30 cm. Using interstem technique allows to gather the benefits of the rootstock 'Marubakaido' and to control excessive vigour with the interstem EM-9.Trabalho apresentado no VIII International Symposium on Temperate Zone Fruits in the Tropics and Subtropics, Florianópolis, 2007

    Bud load and its influence on agronomic performance and wine aromatic composition of ‘Fiano’ grapevine in Southern Brazil

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    The objective of this study was to evaluate the influence of bud load on the agronomic performance and composition of volatile compounds of the ‘Fiano’ grapevine cultivated in Southern Brazil. The experiment was conducted in a commercial vineyard in the municipality of Campo Largo, Paraná (Southern Brazil) in the 2019/2020 and 2020/2021 seasons. Vines were Guyot-pruned and evaluated according to different bud loads: 10, 20, 30 and 40 buds per plant. Agronomic performance, technological maturity and the volatile compounds were evaluated, and the data were submitted for variance analysis. The mean values were compared using the Tukey test (p &lt; 0.05). The volatile compounds in the wines were identified using gas chromatography (GC-MS/HS-SPME). The loads of 30 and 40 buds per plant showed an increase in productivity and the maintenance of the physical characteristics and technological ripeness of the grapes. A higher bud load resulted in a larger leaf area and better values for the Ravaz Index. However, the highest bud load (40 buds per plant) reduced the sprouting and shoot length, while a bud load of 30 buds per plant presented the best agronomic performance in the subtropical region of Southern Brazil. The physical characteristics of the bunches and the technological ripeness were not affected, and the increase in bud load did not alter most of the volatile compounds of ‘Fiano’ wines. However, some volatile compounds, such as diethyl succinate and linalool, presented higher concentrations in wines with the lowest yields (10 buds per plant)

    Spatial variability of nitrogen dioxide and formaldehydeand residential exposure of children in the industrial area of Viadana, Northern Italy

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    Chipboard production is a source of ambient air pollution. We assessed the spatial variability of outdoor pollutants and residentialexposure of children living in proximity to the largest chipboard industry in Italy and evaluated the reliability of exposureestimates obtained from a number of available models. We obtained passive sampling data on NO2and formaldehyde collectedby the Environmental Protection Agency of Lombardy region at 25 sites in the municipality of Viadana during 10 weeks (2017-2018) and compared NO2measurements with average weekly concentrations from continuous monitors. We compared interpo-lated NO2and formaldehyde surfaces with previous maps for 2010. We assessed the relationship between residential proximity tothe industry and pollutant exposures assigned using these maps, as well as other available countrywide/continental models basedon routine data on NO2, PM10, andPM2.5. The correlation between NO2concentrations from continuous and passive samplingwas high (Pearson'sr= 0.89), although passive sampling underestimated NO2especially during winter. For both 2010 and 2017-2018, we observed higher NO2and formaldehyde concentrations in the south of Viadana, with hot-spots in proximity to theindustry. PM10and PM2.5exposures were higher for children at 3.5 km to theindustry, whereas NO2exposure was higher at 1-1.7 km to the industry. Road and population densities were also higher close tothe industry. Findings from a variety of exposure models suggest that children living in proximity to the chipboard industry inViadana are more exposed to air pollution and that exposure gradients are relatively stable over time
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