948 research outputs found
On the morphology of Anisakis pegreffii: a comparative analysis of three microscopic techniques used to build a new parasite atlas
BACKGROUND: Human anisakidosis is a parasitic anthropozoonosis caused by larval
nematodes of the family Anisakidae. Here, we report a detailed description of the
morphology of Anisakis pegreffii third-stage larva performed using a conventional light
and confocal microscopy, and scanning electron microscopy (SEM) that provide a
basis for both phenotypic studies and genetic mutations.
METHODS: The collected larvae from fish were morphologically identified as Anisakis
larvae Type I, and they were characterized by PCR-RFLP to identify the Anisakis
pegreffii specie. Using NC5/NC2 primers, ribosomal genomic regions ITS1, 5.8 SrRNA
and ITS2 of DNA were amplified and PCR products were sequenced. Fifteen larvae
belonging to Anisakis pegreffii were fixed, sectioned, and examined with a light and
confocal microscope and by SEM.
RESULTS: In our studies, have been acquired detailed ultrastructural images, which
have been integrated with those derived from the dissection of the parasite, obtained
with light and confocal microscopy. The structural and ultrastructural images
concerning the third stage larvae of Anisakis pegreffii have been studied, analyzed and
compared among them. The derived overall view has allowed detecting new interesting
details of a well-known parasite and has been schematically showed.
CONCLUSIONS: The aim of this study is to furnish an updated atlas of Anisakis
pegreffii. Confocal microscopy, as well as the light and electron microscopy have
played a pivotal role in the accumulation of new scientific data regarding the anatomical
structures of this nematode. This work is the result of one year of engagement by the
Authors and the outcome is a comprehensive atlas on Anisakis pegreffii microscopy
Theoretical Uncertainties in Red Giant Branch Evolution: The Red Giant Branch Bump
A Monte Carlo simulation exploring uncertainties in standard stellar
evolution theory on the red giant branch of metal-poor globular clusters has
been conducted. Confidence limits are derived on the absolute V-band magnitude
of the bump in the red giant branch luminosity function (M_v,b) and the excess
number of stars in thebump, R_b. The analysis takes into account uncertainties
in the primordial helium abundance, abundance of alpha-capture elements,
radiative and conductive opacities, nuclear reaction rates, neutrino energy
losses, the treatments of diffusion and convection, the surface boundary
conditions, and color transformations.
The uncertainty in theoretical values for the red giant bump magnitude varies
with metallicity between +0.13/-0.12 mag at [Fe/H] = -2.4 and +0.23/-0.21 mag
at [Fe/H] = -1.0 to 0.50 at [Fe/H] =
-1.0. These theoretical values for R_b are in agreement with observations.Comment: 30 pages, 6 figures. To appear in Ap
The Age Dependent Luminosities of the Red Giant Branch Bump, Asymptotic Giant Branch Bump, and Horizontal Branch Red Clump
Color-magnitude diagrams of globular clusters often exhibit a prominent
horizontal branch (HB) and may also show features such as the red giant branch
(RGB) bump and the asymptotic giant branch (AGB) bump. Stellar evolution theory
predicts that the luminosities of these features will depend on the metallicity
and age of the cluster. We calculate theoretical lines of 2 to 12 Gyr constant
age RGB-bumps and AGB-bumps in the V(HB-Bump)--[Fe/H] diagram, which shows the
brightness difference between the bump and the HB as a function of metallicity.
In order to test the predictions, we identify giant branch bumps in new Hubble
Space Telescope color-magnitude diagrams for 8 SMC clusters. First, we conclude
that the SMC cluster bumps are RGB-bumps. The data for clusters younger than ~6
Gyr are in fair agreement the relative age dependent luminosities of the HB and
RGB-bump. The V(HB-Bump)--[Fe/H] data for clusters older then ~6 Gyr
demonstrate a less satisfactory agreement with our calculations. We conclude
that ~6 Gyr is a lower bound to the age of clusters for which the Galactic
globular cluster, age independent V(HB-Bump)--[Fe/H] calibration is valid.
Application of the V(HB-bump)--[Fe/H] diagram to stellar population studies is
discussed.Comment: Accepted for publication in the Astrophysical Journal, 30 pages,
Latex aaspp4.sty, including 7 postscript figure
The shape of the Red Giant Branch Bump as a diagnostic of partial mixing processes in low-mass stars
We suggest to use the shape of the Red Giant Branch (RGB) Bump in metal-rich
globular clusters as a diagnostic of partial mixing processes between the base
of the convective envelope and the H-burning shell. The Bump located along the
differential luminosity function of cluster RGB stars is a key observable to
constrain the H-profile inside these structures. In fact, standard evolutionary
models that account for complete mixing in the convective unstable layers and
radiative equilibrium in the innermost regions do predict that the first
dredge-up lefts over a very sharp H-discontinuity at the bottom of the
convective region. Interestingly enough we found that both atomic diffusion and
a moderate convective overshooting at the base of the convective region
marginally affects the shape of the RGB Bump in the differential Luminosity
Function (LF). As a consequence, we performed several numerical experiments to
estimate whether plausible assumptions concerning the smoothing of the
H-discontinuity, due to the possible occurrence of extra-mixing below the
convective boundary, affects the shape of the RGB Bump. We found that the
difference between the shape of RGB Bump predicted by standard and by smoothed
models can be detected if the H-discontinuity is smoothed over an envelope
region whose thickness is equal or larger than 0.5 pressure scale heights.
Finally, we briefly discuss the comparison between theoretical predictions and
empirical data in metal-rich, reddening free Galactic Globular Clusters (GGCs)
to constrain the sharpness of the H-profile inside RGB stars.Comment: 15 pages, 8 postscript figures, ApJ in pres
Behavioral and clinical characteristics of people receiving medical care for HIV infection in an outpatient facility in Sicily, Italy
Aim: The authors examined a cohort of HIV-positive outpatients at the AIDS Center of Palermo University in Italy in order to identify factors related to the frequency of their visits to the outpatient facility for health care services. Methods: Two hundred and twenty-four HIV-infected subjects were enrolled in the study. Demographic and HIV disease characteristics were recorded and assessed with the number of days accessed to our outpatients unit in univariate and multivariate analyses. The potential relationship with immunological status was also analyzed stratifying the patients into groups according to their CD4+ T-cell counts ( 65500 vs, \u2c2500/mm3, and 65200 vs < 200/mm3). Results: Both univariate and multivariate analyses showed that duration of antiretroviral therapy, \u2c25 years and hypertension were significantly associated with a CD4+ T-cell count of, \u2c2500/mm3, whereas geographic origin (Africa) was associated with a CD4+ T-cell count of, \u2c2200/mm3. Mean number of days the patients sought access to day-care services for laboratory tests was negatively associated with CD4+ T-cell count. Conclusion: Patients with low CD4+ T-cell counts showed higher use of health care services, demonstrating how early HIV diagnosis can help to reduce health care costs. The CD4+ T-cell cut-off of 200 cells emphasizes the importance of identifying and managing HIV infection among hard-to-reach groups like vulnerable migrants. In our sle, the illegal status of immigrants does not influence the management of their HIV/AIDS condition, but the lack of European health card that documents the current antiretroviral status, could interfere with the efforts to eradicate AIDS. A better understanding of the major determinants of HIV treatment costs has led to appropriate large-scale actions, which in turn has increased resources and expanded intervention programs. Further guidance should be offered to hard-to-reach groups in order to improve early AIDS diagnosis, and procedures for identifying and managing these vulnerable subjects should be made available to care commissioners and service providers
18F-FDG PET-Derived Volume-Based Parameters to Predict Disease-Free Survival in Patients with Grade III Breast Cancer of Different Molecular Subtypes Candidates to Neoadjuvant Chemotherapy
We investigated whether baseline [F-18] Fluorodeoxyglucose (F-18-FDG) positron emission tomography (PET)-derived semiquantitative parameters could predict disease-free survival (DFS) in patients with grade III breast cancer (BC) of different molecular subtypes candidate to neoadjuvant chemotherapy (NAC). For each F-18-FDG-PET/CT scan, the following parameters were calculated in the primary tumor (SUVmax, SUVmean, MTV, TLG) and whole-body (WB_SUVmax, WB_MTV, and WB_TLG). Receiver operating characteristic (ROC) analysis was used to determine the capability to predict DFS and find the optimal threshold for each parameter. Ninety-five grade III breast cancer patients with different molecular types were retrieved from the databases of the University Hospital of Padua and the University Hospital of Ferrara (luminal A: 5; luminal B: 34; luminal B-HER2: 22; HER2-enriched: 7; triple-negative: 27). In luminal B patients, WB_MTV (AUC: 0.75; best cut-off: WB_MTV > 195.33; SS: 55.56%, SP: 100%; p = 0.002) and WB_TLG (AUC: 0.73; best cut-off: WB_TLG > 1066.21; SS: 55.56%, SP: 100%; p = 0.05) were the best predictors of DFS. In luminal B-HER2 patients, WB_SUVmax was the only predictor of DFS (AUC: 0.857; best cut-off: WB_SUVmax > 13.12; SS: 100%; SP: 71.43%; p < 0.001). No parameter significantly affected the prediction of DFS in patients with grade III triple-negative BC. Volume-based parameters, extracted from baseline F-18-FDG PET, seem promising in predicting recurrence in patients with grade III luminal B and luminal B- HER2 breast cancer undergoing NAC
Intermediate mass stars: updated models
A new set of stellar models in the mass range 1.2 to 9 is
presented. The adopted chemical compositions cover the typical galactic values,
namely and . A comparison among
the most recent compilations of similar stellar models is also discussed. The
main conclusion is that the differencies among the various evolutionary results
are still rather large. For example, we found that the H-burning evolutionary
time may differ up to 20 %. An even larger disagreement is found for the
He-burning phase (up to 40-50 %). Since the connection between the various
input physics and the numerical algorithms could amplify or counterbalance the
effect of a single ingredient on the resulting stellar model, the origin of
this discrepancies is not evident. However most of these discrepancies, which
are clearly found in the evolutionary tracks, are reduced on the isochrones. By
means of our updated models we show that the ages inferred by the theory of
stellar evolution is in excellent agreement with those obtained by using other
independent methods applied to the nearby Open Clusters. Finally, the
theoretical initial/final mass relation is revised.Comment: 35 pages, 24 figures, 4 tables, accepted for publication in the
Astrophisycal Journa
Improving Mechanical Properties and Reaction to Fire of EVA/LLDPE Blends for Cable Applications with Melamine Triazine and Bentonite Clay
The high flame-retardant loading required for ethylene-vinyl acetate copolymer blends with polyethylene (EVA-PE) employed for insulation and sheathing of electric cables represents a significant limitation in processability and final mechanical properties. In this work, melamine triazine (TRZ) and modified bentonite clay have been investigated in combination with aluminum trihydroxide (ATH) for the production of EVA-PE composites with excellent fire safety and improved mechanical properties. Optimized formulations with only 120 parts per hundred resin (phr) of ATH can achieve self-extinguishing behavior according to the UL94 classification (V0 rating), as well as reduced combustion kinetics and smoke production. Mechanical property evaluation shows reduced stiffness and improved elongation at break with respect to commonly employed EVA-PE/ATH composites. The reduction in filler content also provides improved processability and cost reductions. The results presented here allow for a viable and halogen-free strategy for the preparation of high performing EVA-PE composites
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