4,420 research outputs found
Xylem plasticity in Pinus pinaster and Quercus ilex growing at sites with different water availability in the Mediterranean region: relations between Intra-Annual Density Fluctuations and environmental conditions.
Fluctuations in climatic conditions during the growing season are recorded in Mediterranean tree-rings and often result in intra-annual density fluctuations (IADFs). Dendroecology and quantitative wood anatomy analyses were used to characterize the relations between the variability of IADF traits and climatic drivers in Pinus pinaster Aiton and Quercus ilex L. growing at sites with different water availability on the Elba island in Central Italy. Our results showed that both species present high xylem plasticity resulting in the formation of L-type IADFs (L-IADFs), consisting of earlywood-like cells in latewood. The occurrence of such IADFs was linked to rain events following periods of summer drought. The formation of L-IADFs in both species increased the hydraulic conductivity late in the growing season, due to their larger lumen area in comparison to "true latewood". The two species expressed greater similarity under arid conditions, as unfavorable climates constrained trait variation. Wood density, measured as the percentage of cell walls over total xylem area, IADF frequency, as well as conduit lumen area and vessel frequency, specifically in the hardwood species, proved to be efficient proxies to encode climate signals recorded in the xylem. The response of these anatomical traits to climatic variations was found to be species- and site-specific
Blockade of Immunosuppressive Cytokines Restores NK Cell Antiviral Function in Chronic Hepatitis B Virus Infection
NK cells are enriched in the liver, constituting around a third of intrahepatic lymphocytes. We have previously demonstrated that they upregulate the death ligand TRAIL in patients with chronic hepatitis B virus infection (CHB), allowing them to kill hepatocytes bearing TRAIL receptors. In this study we investigated whether, in addition to their pathogenic role, NK cells have antiviral potential in CHB. We characterised NK cell subsets and effector function in 64 patients with CHB compared to 31 healthy controls. We found that, in contrast to their upregulated TRAIL expression and maintenance of cytolytic function, NK cells had a markedly impaired capacity to produce IFN-gamma in CHB. This functional dichotomy of NK cells could be recapitulated in vitro by exposure to the immunosuppressive cytokine IL-10, which was induced in patients with active CHB. IL-10 selectively suppressed NK cell IFN-gamma production without altering cytotoxicity or death ligand expression. Potent antiviral therapy reduced TRAIL-expressing CD56 bright NK cells, consistent with the reduction in liver inflammation it induced; however, it was not able to normalise IL-10 levels or the capacity of NK cells to produce the antiviral cytokine IFN-gamma. Blockade of IL-10 +/- TGF-beta restored the capacity of NK cells from both the periphery and liver of patients with CHB to produce IFN-gamma, thereby enhancing their non-cytolytic antiviral capacity. In conclusion, NK cells may be driven to a state of partial functional tolerance by the immunosuppressive cytokine environment in CHB. Their defective capacity to produce the antiviral cytokine IFN-gamma persists in patients on antiviral therapy but can be corrected in vitro by IL-10+/- TGF-beta blockade
long term administration of low doses of mycotoxins in poultry 1 residues of ochratoxin a in broilers and laying hens
Abstract The occurrence and amount of residues of ochratoxin A (OA) in poultry tissues and organs were investigated in a trial aimed at measuring the effects of contamination approaching the patterns more frequently found in natural situations (i.e., small doses of OA in the diet for long periods). Hubbard male broilers and laying hens were treated with an OA-contaminated feed (50 ppb) from the 14th day of age onward. Both groups were further divided into subgroups, some of which underwent continual treatment (64 and 169 days, respectively) and others that were withdrawn from administration (maximum 28 and 82 days, respectively). Determination of residues was performed by high performance liquid chromatography. Residues in liver were higher in broilers (up to 11.0 ppb) than in hens (1.5 ppb), whereas the reverse occurred in kidney (up to .8 and 5.8 ppb, respectively). Residues (.8 ppb) were also in hen thigh muscle but not in breast muscle. Residues of OA in poultry appear to be of possible public health concern. Suggestions for monitoring are given
Optical fiber technology enables smart needles for epidurals. An in-vivo swine study
Nowadays, epidural space identification is made by using subjective and manual techniques characterized by failure rates up to 7%. In this work, we propose a fiber optic sensor technology based needle guidance system, that is directly inspired by the most common technique currently used for epidurals; through real-time strain measurements, the fiber Bragg grating integrated inside the needle lumen is able to effectively perceive the typical force drop occurring when the needle enters the epidural space. An in vivo swine study demonstrates the validity of our approach, paving the way for the development of lab-in-a-needle systems
Microeconomic Flexibility in Latin America
We characterize the degree of microeconomic inflexibility in several Latin American economies and find that Brazil, Chile and Colombia are more flexible than Mexico and Venezuela. The difference in flexibility among these economies is mainly explained by the behavior of large establishments, which adjust more promptly in the more flexible economies, especially when accumulated shocks are substantial. We also study the path of flexibility in Chile and show that it declined in the aftermath of the Asian crisis. This decline can account for a substantial fraction of the sharp fall in TFP-growth in Chile since 1997 (from 3.1 percent per year for the preceding decade, to about 0.3 percent after). Moreover, if it were to persist, it could permanently shave almost half of a percent off Chile’s structural rate of growth.
A prototype of fine granularity lead-scintillating fiber calorimeter with imaging read out
The construction and tests performed on a smal prototype of lead-scintillating fiber calorimeter instrumented with multianode photomultipliers are reported. The prototype is 15 cm wide, 15 radiation lenghts deep and is made of 200 layers of 50 cm long fibers. One side of the calorimeter has been instrumented with an array of 3 × 5 multianode R8900-M16 Hamamatsu photomultipliers, each segmented with a matrix of 4 × 4 anodes. The read-out granularity is 240 pixels 11 × 11 mm 2 reading about 64 fibers each. They are interfaced to the 6 × 6 mm 2 pixelled photocade with truncated pyramid light guides made of BC-800 plastic, UV transparent. Moreover each photomultiplier provides also the OR information of the last 12 dynodes. This information can be useful for trigger purposes. The response of the individual anodes, their relative gain and cross-talk has been measured with a 404 nm picosecond laser illuminating only a few fibers on the opposite side of the read-out. We also present first results of the calorimeter response to cosmic rays and electron beam data collected at BTF facility in Frascati
Pseudoscalar glueball and mixing
We have performed a dynamical analysis of the mixing in the pseudoscalar
channel with the goal of understanding the existence and behavior of the
pseudoscalar glueball. Our philosophy has not been to predict precise values of
the glueball mass but to exploit an adequate effective theory to the point of
breaking and to analyze which kind of mechanisms restore compatibility with
data. Our study has lead to analytical solutions which allow a clear
understanding of the phenomena. The outcome of our calculation leads to a large
mass glueball MeV, to a large glue content of the
and to mixing angles in agreement with previous numerical studies.Comment: 12 pages, 8 figure
SV-IV Peptide1–16 reduces coagulant power in normal Factor V and Factor V Leiden
Native Factor V is an anticoagulant, but when activated by thrombin, Factor X or platelet proteases, it becomes a procoagulant. Due to these double properties, Factor V plays a crucial role in the regulation of coagulation/anticoagulation balance
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