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There have been few studies realized that evaluate the effects of adopting
different nutritional systems in more than one phase of cattle production on
carcass and meat characteristics. This study was realized to evaluate carcass
and meat characteristics from bulls submitted to different nutritional systems
during two production phases. The experiment was conducted at
Figueira’s farm during two production phases: I (cow–calf)
– 80 calves (99.6±2.72 days of age and
109.7±2.99 kg of BW) with their mothers were randomly assigned into
two supplemental diets: cow–calf mineral supplement
(n=40) or cow–calf creep-feeding
(n=40); II (stocker) – the same 80
calves (201.2±2.11 days of age and 190.2±3.37 kg of BW)
were redistributed into two production systems: stocker pasture
(n=40) or stocker feedlot (SF;
n=40). After, all 80 animals were kept on a pasture
system (III) for 290 days, and then finished in a feedlot system (IV) for more
33 days. Then, they were slaughtered at an average 764.2±3.06 days of
age and at 499.2±3.33 kg of final BW. After slaughter, the average
daily gain was calculated, and the carcass and meat characteristics were
measured. The statistical model design used was completely randomized in a
2×2 factorial arrangement (two treatment groups on
cow–calf phase and two treatment groups on stocker phase). The single
effects between the groups in each phase and the interactions between both
phases (cow–calf v. stocker) were analyzed. The
results were compared by Fisher’s test, using the R statistical
software. A cow–calf by stocker phases interaction occurred for
carcass conformation and fiber diameter. For single effects, the greatest
influences observed were in the stocker phase. The feedlot group was slaughtered
17 days earlier, with greater final BW (3.8%), hot carcass weight
(5.7%), average daily gain (6.9%), dressing percentage
(1.8%), carcass length (1.8%), carcass width
(1.5%), longissimus muscle area (4.8%)
and muscle depth (2.3%) than pasture group. The SF group also had
influence on fat color; showing higher L* and lower
b* values. These results reveal that bulls
reared in feedlot at the stocker phase have higher muscle development and that
the stocker phase has the greatest potential to influence carcass
characteristics and meat quality.
In consequence of the decision made by the Fifth General Assembly of the I.A.U. I have been entrusted, from January 1936, with the direction of the Central Bureau for the International Service of Latitudes.
I am much indebted to Prof. Kimura, who preceded me as Director and to Prof. Kohlschütter, Director of the Geodetic Institute of Potsdam, for information and advice, which has been of great assistance to me; therefore I desire to acknowledge to them my deep gratitude.
Photometric observations of V1054 Oph (Wolf 630 AB, mv = 9.69) and of the comparison star HD 152678 (mv = 8.1) were carried out in the UBV bands at Catania Astrophysical Observatory on 1994, June 15, using the 91 cm Cassegrain telescope equipped with an improved version of the twin-beam photometer URSULA (De Biase et al. 1988). We have detected a relatively low-intensity flare event preceded by a pre-flare dip of low amplitude and the exceptionally long duration of 36 min. The integration times were 10, 5 and 5 sec in the U, B and V bands, respectively. The variable and the comparison stars were observed simultaneously in the two independent channels of the twin-beam photometer. The sky background was subtracted from the photon count rates of V1054 Oph and its comparison star in each spectral band, and the flux of the variable was normalized to that of the comparison star.
During UBV photoelectric measurements of G102-21 - a dM3 star recently discovered as a remarkably active X-ray source by Micela et al. (1995) - we have observed the flare shown in Fig. 1 (left panel). The observed flux increase at flare maximum and the energy output (cf. Table 1) make this event one of the largest amplitude and most energetic flares ever detected on UV Cet-type stars.
The ratios EU/EB (=8.9) and EU/EV (=3.9) are more than 7 and 2 times larger, respectively, than the mean values found for typical dMe flares by Lacy et al. (1976). Moreover, assuming the empirical relation between the absolute magnitude MV and the mean energy dissipation during a flare (Gurzadyan 1980), the energy released in the U band exceeds the predicted one by a factor of ∼ 3 · 103. Clearly, we observed a rather peculiar and rare event that does not appear to be a typical flare on red-dwarf stars.
Compact solar flares are triggered by sudden energy release in magnetically confined plasma. This class of flares is well suited to be studied with numerical hydrodynamic models. In particular, one can compare the evolution of observed and synthetic X-ray spectra, computed under various assumptions for the mechanism of impulsive energy deposition, to constrain theoretical models and their parameter space. We discuss recent results on solar flares along this line, non thermal to models of energy depositions by relativistic electron beams. We shall also discuss possible applications of X-ray spectral synthesis to stellar flares.
In this work we report on the characteristics of GaAs/AlGaAs heterostructures with a symmetric double two-dimensional electron gas (D-2DEG). Optical characterization was made by room temperature photoreflectance (PR) spectroscopy as well as electrical properties were determinated using the quantum Hall effect measurements at 2K. In order to study the surface effects on the conduction band profile, three samples with different GaAs cap layer thickness (25, 60 and 80 nm) were grown by the molecular beam epitaxy. Photoreflectance spectra at room temperature show the wide-period Franz-Keldysh oscillations between 1.42 and 1.70 eV originated by the surface electric field. The analysis of these oscillations shows that the surface electric field varies from 503 to 120 kV/cm whereas the thickness of the cap layer increases that was produced by the reduction of the depletion zone near the surface. Using QHE measurements we found that electron density increases if the surface electric field decreases.
In classical T Tauri stars (CTTS) strong shocks are formed where the accretion funnel impacts with the denser stellar chromosphere. Although current models of accretion provide a plausible global picture of this process, some fundamental aspects are still unclear: the observed X-ray luminosity in accretion shocks is order of magnitudes lower than predicted; the observed density and temperature structures of the hot post-shock region are puzzling and still unexplained by models.
To address these issues we performed 2D MHD simulations describing an accretion stream impacting onto the chromosphere of a CTTS, exploring different configurations and strengths of the magnetic field. From the model results we then synthesized the X-ray emission emerging from the hot post-shock, taking into account the local absorption due to the pre-shock stream and surrounding atmosphere.
We find that the different configurations and strengths of the magnetic field profoundly affect the hot post-shock properties. Moreover the emerging X-ray emission strongly depends also on the viewing angle under which accretion is observed. Some of the explored configuration are able to reproduce the observed features of X-ray spectra of CTTS.
The structure and dynamics of young stellar object (YSO) accretion shocks depend strongly on the local magnetic field strength and configuration, as well as on the radiative transfer effects responsible for the energy losses. We present the first 3D YSO shock simulations of the interior of the stream, assuming a uniform background magnetic field, a clumpy infalling gas, and an acoustic energy flux flowing at the base of the chromosphere. We study the dynamical evolution and the post-shock structure as a function of the plasma-beta (thermal pressure over magnetic pressure). We find that a strong magnetic field (~hundreds of Gauss) leads to the formation of fibrils in the shocked gas due to the plasma confinement within flux tubes. The corresponding emission is smooth and fully distinguishable from the case of a weak magnetic field (~tenths of Gauss) where the hot slab demonstrates chaotic motion and oscillates periodically.
Hepatitis C virus (HCV) infection is associated with oxidative stress and vitamin A possesses antioxidant activity. The objective of the present study was to investigate vitamin A nutritional status in chronic hepatitis, liver cirrhosis and hepatocellular carcinoma (HCC), according to biochemical, functional and dietetic indicators correlating these findings with liver function, liver damage and death. Vitamin A nutritional status was analysed by serum retinol levels, dietetic indicators and functional indicators. A total of 140 patients with HCV-related liver disease were enrolled. Vitamin A deficiency was detected in 54·3 % of all patients, and there was a progressive drop in serum retinol levels from chronic hepatitis C patients towards cirrhosis and HCC patients. Increased total bilirubin, liver transaminases and prothrombin time, presence of hepatic encephalopathy and ascites were related to reduced serum retinol levels, and values ≤ 0·78 μmol/l of serum retinol were associated with liver-related death. A high prevalence of inadequate intake of vitamin A was observed in all stages of chronic liver disease. The functional indicator was not an adequate parameter for evaluating the vitamin A nutritional status. Therefore, serum retinol concentration is related to severity of the disease, liver complications and mortality. The effectiveness of nutritional counselling and measures of intervention in this group in improving vitamin A nutritional status should be examined further in a controlled study.
Low temperature (400°C) deposition of ferromagnetic Ni-Mn-Ga thin films is successfully performed via rf magnetron sputtering technique using co-deposition of two targets Ni50Mn50 and Ni50Ga50 on sapphire (0001) and Si (100) substrates. The films are in part amorphous with significant degree of crystallinity. The obtained crystallographic structure is shown to be substrate-dependent. Films on both substrates are ferromagnetic at room temperature (Curie temperature ∼ 332.5K) with well-defined hysteresis loops, low coercivity (∼ 100 Oe) and a saturation magnetization of ∼ 200 emu/cc. At low temperature (5 K), both films show increased magnetization value with wider hysteresis loops having higher coercivity and remanent magnetization. The process is therefore effective in achieving the appropriate thermodynamic conditions to deposit thin films of the Ni-Mn-Ga austenitic phase (highly magnetic at room temperature) at relatively low substrate temperature without the need for post-deposition annealing or further thermal treatment, which is prerequisite for the device fabrication.
We analyzed the epidemiologic characteristics and risk factors for surgical site infection (SSI) in kidney transplant recipients. From among 1,939 kidney transplant recipients, 120 with corresponding control subjects were evaluated in this study (1:1 ratio). Reoperation, chronic glomerulonephritis, acute graft rejection, delayed graft function, diabetes, and high body mass index were identified in the analysis as risk factors for SSI.
Traumatic memory is a key symptom in psychological trauma victims and may remain vivid for several years. Psychotherapy has shown that neither the psychopathological signs of trauma nor the expression of traumatic memories are static over time. However, few studies have investigated the neural substrates of psychotherapy-related symptom changes.
We studied 16 subthreshold post-traumatic stress disorder (PTSD) subjects by using a script-driven symptom provocation paradigm adapted for single photon emission computed tomography (SPECT) that was read aloud during traumatic memory retrieval both before and after exposure-based and cognitive restructuring therapy. Their neural activity levels were compared with a control group comprising 11 waiting-list subthreshold PTSD patients, who were age- and profile-matched with the psychotherapy group.
Significantly higher activity was observed in the parietal lobes, left hippocampus, thalamus and left prefrontal cortex during memory retrieval after psychotherapy. Positive correlations were found between activity changes in the left prefrontal cortex and left thalamus, and also between the left prefrontal cortex and left parietal lobe.
Neural mechanisms involved in subthreshold PTSD may share neural similarities with those underlying the fragmented and non-verbal nature of traumatic memories in full PTSD. Moreover, psychotherapy may influence the development of a narrative pattern overlaying the declarative memory neural substrates.
The organic carbon accumulation rate in mangrove ecosystem was reported to be important sink of carbon as well as that in boreal peat accumulation. For the estimation of 10 years scale organic carbon accumulation rates at mangrove plantation coastal area, the 210Pb is expected to be suitable for decades scale estimation by its half-life, though it has possibility of bio-/physical- turbation effect in applying 210Pb chronology, especially in Asian mangrove ecosystem where the anthropogenic physical turbation by coastal fishery is vigorous. We studied the organic carbon and 210Pb accumulation rates in subtropical mangrove coastal ecosystems in Japan, Vietnam and Thailand to remove the effect of bio- anthropogenic turbation on organic carbon accumulation. We finally concluded that 210Pb was applicable to estimate organic carbon accumulation rates in these ecosystems. The measured organic carbon accumulation rates using 210Pb in mangrove coastal ecosystems of Japan, Vietnam and Thailand were
$0.22 - 6.0$
t-C ha-1 y-1.
The ability to predict the consequences of an accidental release of radionuclides relies mainly on the level of understanding of the mechanisms involved in radionuclides interactions with different components of agricultural and natural ecosystems and their formalisation into predictive models. Numerous studies and databases about contaminated agricultural and natural areas have been obtained but their use to enhance our prediction ability has been largely limited by their unresolved variability. Such variability seems to stem from incomplete knowledge about radionuclide interactions with the soil matrix, soil moisture, biological elements in the soil and additional pollutants, which may be found in such soils.
In this project, we investigated mainly the role of the biological elements (plants, mycorrhiza, microbes) in: radionuclide sorption/desorption in soils and radionuclide uptake/release by plants. Because of their chemical nature importance, the bioavailability of three radionuclides: caesium, strontium, and technetium have been followed. The role of one additional non-radioactive pollutant (copper) has been scrutinised.
Role of microorganisms (Kd for caesium and strontium in organic soils is much greater in the presence of microorganisms than in their absence), plant physiology (changes in plant physiology affect radionuclide uptake by plants), the presence of mycorrhizal fungi (interferes with the uptake of radionuclides by plants), have been demonstrated.
Knowledge acquired from these experiments has been incorporated into two mechanistic models CHEMFAST and BIORUR specifically modelling radionuclide sorption/desorption from soil matrices and radionuclide uptake by/release from plants. These mechanistic models have been incorporated into an assessment model to enhance its prediction ability.
The present study is the second part of a program of characterization of the site surrounding the SoGIN Garigliano Nuclear Power Plant (Southern Italy), which is currently involved in decommissioning activities. In the first phase of the project the reference groups of the population were established on the basis of a socio-economical study of the site; the radiological doses due to the assumed radioactive releases during the decommissioning phase were calculated by using climatological, hydrological, geomorphological parameters of the studied area; transport and diffusion specific models of some radionuclides in the environment were implemented to calculate the dose using specific evaluation software. The second part of the study focuses on the project of an environmental network designed in order to ensure the continuous monitoring of the radioactive release concentrations. All the criteria for the choice of grid points, by considering specific paths of transfer in the environment, were established for all the environmental compartments. A field campaign was carried out aiming to assess the “zero level" due to the natural radioactivity and past anthropogenic activities.
The BioMoSA (Biosphere Models for Safety Assessment of Radioactive Waste Disposal) project was part of the EC fifth framework research program. The main goal of this project was the improvement of the scientific basis for the application of biosphere models in the framework of long-term safety studies of radioactive waste disposal facilities. Another aim of the project was to provide operators and regulatory bodies with guidelines for performance assessments of repository systems. The study focused on the development and application of site-specific models and a generic biosphere tool BIOGEM (BIOsphere GEneric Model), using the experience from National programs and the IAEA BIOMASS reference biosphere methodology. The models were applied to 5 typical locations in Europe, resulting in estimates of the annual individual doses to the critical groups and the ranking of the importance of the pathways for each of the sites. The results of the site-specific and generic models were then compared. Uncertainty in the results was estimated by means of stochastic calculations which allowed a comparison of the overall model uncertainty with the variability across the different sites considered.
The metal bioaccumulation levels in target-organs associated with microlocalisation approaches at the subcellular level provide information for the understanding of the metabolic metal cycle. These findings could be used to select relevant biomarkers of exposure and to focus on specific contaminated organelles to study potential biological effects. Moreover, the metal accumulated in the cytosol fraction can be bound to macromolecules in order to be eliminated and/or to induce a potential cellular effect. Tissular distribution, transfer efficiency from water and subcellular fractionation were investigated on the freshwater bivalve, Corbicula fluminea after uranium aqueous exposure. The subcellular fractionation was performed while measuring associated uranium to each cellular different fraction as follows: cellular debris and nuclei, mitochondria and lysosomes, membranes, microsomes and cytosol. In our experimental conditions, the accumulation in the cytosol fraction was low and more than 80 % of the total uranium in gills and visceral mass was accumulated in the insoluble fraction. Main results presented in this paper come from light and electron microscope observations of subcellular fractions (nuclei/debris and lysosomes/mitochondria) in order to validate the efficiency of the fractionation technique. An adaptation of the fractionation technique is proposed. This set of data confirms high differences of fractionation efficiency as a function of used fractionation technique and organs/biological model.
Some 3×109 kg of phosphogypsum (PG) wastes are annually generated by two fertiliser-production factories in Huelva (south-western Spain). PG has relatively high concentrations of 226Ra and other radionuclides, with an special concern due to the 222Rn emissions. These wastes could be used to improve the fertility of agriculture soils in a large former marsh area of the Guadalquivir river. Thus, it is interesting to study the levels and behaviour of natural radionuclides within this system to evaluate the radioactive impact of this amendment. An agronomical test is being conducted by one of the authors in an experimental farm in Lebrija (Seville). The soils are treated with 13 and 26 t ha-1 of PG, 30 t ha-1 of manure. Each treatment was repeated twice and continued for two years with beetroot and cotton plant production. We are measuring 226Ra (by alpha counting and gamma spectrometry) and U isotopes (by alpha spectrometry and ICP-MS analysis) in drainage waters, soils and vegetal-tissues samples. The PG used in the treatment has 620 ± 70 Bq kg-1 of 226Ra. The drainage waters have 226Ra contents similar to those from non-contaminated natural waters, but the uranium concentrations are one order of magnitude higher. Our results are suggesting that the major uranium input comes from the application of phosphate-fertiliser. No significant levels of radionuclides were found in the vegetal tissues.
Kinetic transfer coefficients are important parameters to understand and reliably model the behaviour of non-conservative radionuclides in aquatic environments. This report pertains to a series of radiotracer experiments on 239Pu uptake in natural unfiltered waters from the Hueznar reservoir (southern Spain). The experimental procedure ensures the preservation of environmental conditions and the dissolved Pu activity was measured by liquid scintillation technique. The data suggest that the main pathways for Pu uptake consist of two parallel and reversible reactions. We studied the effects of suspended matter concentrations and the specific surface area on the kinetic transfer coefficients.