1,280 research outputs found
Radiative transfer effects on Doppler measurements as sources of surface effects in sunspot seismology
We show that the use of Doppler shifts of Zeeman sensitive spectral lines to
observe wavesn in sunspots is subject to measurement specific phase shifts
arising from, (i) altered height range of spectral line formation and the
propagating character of p mode waves in penumbrae, and (ii) Zeeman broadening
and splitting. We also show that these phase shifts depend on wave frequencies,
strengths and line of sight inclination of magnetic field, and the polarization
state used for Doppler measurements. We discuss how these phase shifts could
contribute to local helioseismic measurements of 'surface effects' in sunspot
seismology.Comment: 12 pages, 4 figures, Accepted for publication in the Astrophysical
Journal Letter
Eating Disorders
Anorexia and bulimia are diseases known since ancient times, but in recent years their frequency has been continuously increasing in most industrialized countries. The etiology of these disorders can be traced back to the interaction between genetic predisposition, childhood experiences, and cultural pressures. As regards the course, a certain tendency to chronicity can be observed, and in extreme cases, they can cause death. According to the diagnostic classification of the DSM-5, eating disorders include anorexia nervosa, bulimia nervosa, binge eating disorder (which, compared to DSM-IV, becomes a diagnostic category in its own right), and other specified feeding and eating disorders (OSFED). Both anorexia and bulimia cause potentially serious medical complications. To maximize the chances of good outcomes a multidisciplinary intervention is necessary with staff including professionally heterogeneous figures: a psychiatrist, a psychologist, and a nutritionist. Therapeutic success for these patients is limited. Eating disorders require, among psychiatric disorders, the greatest possible collaboration between different professional figures with different specializations
3D photospheric velocity field of a Supergranular cell
We investigate the plasma flow properties inside a Supergranular (SG) cell,
in particular its interaction with small scale magnetic field structures. The
SG cell has been identified using the magnetic network (CaII wing brightness)
as proxy, applying the Two-Level Structure Tracking (TST) to high spatial,
spectral and temporal resolution observations obtained by IBIS. The full 3D
velocity vector field for the SG has been reconstructed at two different
photospheric heights. In order to strengthen our findings, we also computed the
mean radial flow of the SG by means of cork tracing. We also studied the
behaviour of the horizontal and Line of Sight plasma flow cospatial with
cluster of bright CaII structures of magnetic origin to better understand the
interaction between photospheric convection and small scale magnetic features.
The SG cell we investigated seems to be organized with an almost radial flow
from its centre to the border. The large scale divergence structure is probably
created by a compact region of constant up-flow close to the cell centre. On
the edge of the SG, isolated regions of strong convergent flow are nearby or
cospatial with extended clusters of bright CaII wing features forming the knots
of the magnetic network.Comment: 7 pages, submitted to A&A, referee's comments include
Nonlinear response of single-molecule nanomagnets: equilibrium and dynamical
We present an experimental study of the {\em nonlinear} susceptibility of
Mn single-molecule magnets. We investigate both their
thermal-equilibrium and dynamical nonlinear responses. The equilibrium results
show the sensitivity of the nonlinear susceptibility to the magnetic
anisotropy, which is nearly absent in the linear response for axes distributed
at random. The nonlinear dynamic response of Mn was recently found to be
very large and displaying peaks reversed with respect to classical
superparamagnets [F. Luis {\em et al.}, Phys. Rev. Lett. {\bf 92}, 107201
(2004)]. Here we corroborate the proposed explanation -- strong field
dependence of the relaxation rate due to the detuning of tunnel energy levels.
This is done by studying the orientational dependence of the nonlinear
susceptibility, which permits to isolate the quantum detuning contribution.
Besides, from the analysis of the longitudinal and transverse contributions we
estimate a bound for the decoherence time due to the coupling to the phonon
bath.Comment: 13 pages, 8 figures, resubmitted to Phys. Rev. B with minor change
Three-minute wave enhancement in the solar photosphere
It is a well-known result that the power of five-minute oscillations is
progressively reduced by magnetic fields in the solar photosphere. Many authors
have pointed out that this fact could be due to a complex interaction of many
processes: opacity effects, MHD mode conversion and intrinsic reduced acoustic
emissivity in strong magnetic fields. While five-minute oscillations are the
dominant component in the photosphere, it has been shown that chromospheric
heights are in turn dominated by three-minute oscillations. Two main theories
have been proposed to explain their presence based upon resonance filtering in
the atmospheric cavity and non linear interactions. In this work we show,
through the analysis of IBIS observations of a solar pore in the photospheric
Fe I 617.3 nm line, that three-minute waves are already present at the height
of formation of this line and that their amplitude depends on the magnetic
field strength and is strictly confined in the umbral region.Comment: A&A accepte
The role of miRNA-133b and its target gene SIRT1 in FAP-derived desmoid tumor.
Signaling pathways have a key role in driving the uncontrolled development of familial adenomatous polyposis (FAP)- associated and sporadic desmoid tumors (DTs). The relationship between the Wnt/b-catenin signaling pathway and DTs has been extensively studied, but no reliable biomarkers able to detect their histological subtype have been identified for the accurate diagnosis. In this study we studied the differences in miRNA expression between sporadic (20 patients) and FAP-associated DTs (7 patients) using microarray confirmed by quantitative PCR (qPCR). The analysis showed 19 dysregulated miRNAs. Among them miR-133b levels were significantly lower in FAP-associated DT than in sporadic DT. Therefore, two mRNAs, associated to miR-133b and β-catenin expression, the SIRT1 and ELAVL1were analyzed. The qPCR analysis showed that SIRT1 mRNA levels were significantly up-regulated in FAP-associated DT than in sporadic DT, whereas no differences in ELAVL1 expression was observed between these two DT types. In addition, a negative correlation was observed between miR-133b and SIRT1 in FAP-associated DTs, but not in sporadic DTs. The miR-133b-SIRT1-β-catenin axis may represent a novel mechanism underlying progression of FAP-associated D
The accuracy of NIRS in predicting chemical composition and fibre digestibility of hay-based total mixed rations
The aim of this study was to develop near-infrared spectroscopy (NIRS) prediction models for the estimation of chemical components and the fibre undegradable fractions (uNDF) of hay-based total mixed rations (TMR). A total of 205 TMR samples were used for the study. All the chemical components were measured using standard AOAC reference methods and expressed as percentages of dry matter (DM). Prediction models were developed using both cross- and independent validation and different mathematical treatments applied on spectral data. The best spectral treatment was chosen based on the method which simultaneously achieved the lowest root mean square error and the highest explained variance in cross-validation. The coefficient of determination in external validation (R2P) was the greatest for starch prediction model (R2P = 0.84), followed by acid detergent fibre (ADF; R2P = 0.79), and amylase-treated ash-corrected NDF with addition of sodium sulphite (aNDFom) and crude protein prediction models (CP; R2P = 0.73). The concordance correlation coefficient (CCC) in validation ranged from 0.66 (ash prediction model) to 0.92 (starch prediction model), indicating substantial to accurate models’ predictive ability. This study indicated that NIRS can be a screening method for the prediction of CP, Starch, aNDFom, ADF, acid detergent lignin (ADL), uNDF and Ash. The use of TMR utilised in various herds provided high variability for the NIRS calibration dataset, implying that the developed NIRS pre-diction models could be applicable to TMR collected from herds located in the Parmigiano Reggiano cheese production area.Highlights NIRS can be successfully employed to determine quickly and at cost-effective different compositional and digestibility traits in hay-based TMR. TMR analysis predicted by NIRS can support nutritionists in the formulation of diets containing a proper nutrient profile to sustain physiological, metabolic, and immunological processes. The use of NIR technology for TMR analysis can allow frequent monitoring of rations and increasingly timely corrections, maximising cows’ diet utilisation and conversion of the ingested feed
Time-budget of horses reared for meat production: Influence of stocking density on behavioural activities and subsequent welfare
Horses reared for meat production can be kept in intensive breeding farms where they are
housed in group pens at high stocking densities. The present study aimed to evaluate whether the
expressed behaviours correlated with stocking density, and to compare their time-budget with that
of wild-living horses. An ethogram of 13 mutually exclusive behavioural activities was developed.
Behavioural observations were performed over a 72 h period on group pens selected on the basis
of stocking density and the homogeneity of breed, age, height at the withers, and time since
arriving at the farm. Scan sampling (n = 96 scans/horse/day) was used on 22 horses. The mean
frequency (%) standard deviation (SD) for each behavioural activity was calculated to obtain
the time-budget. The associations between time-budget and stocking density were evaluated
using a bivariate analysis. The relationships were analysed by Pearson’s correlation coecient (r).
Our results show that locomotion, playing, and self-grooming positively correlated with a reduction
in stocking density, indicating the potential to use these behaviours as positive welfare indicators for
young horses kept in group pens. The data also revealed an unusual time-budget, where the main
behavioural activity expressed was standing (30.56% 6.56%), followed by feeding (30.55% 3.59%),
lying (27.33% 2.05%), and locomotion (4.07% 1.06%)
Effects of different feeding frequencies on growth, feed utilisation, digestive enzyme activities and plasma biochemistry of gilthead sea bream (Sparus aurata) fed with different fishmeal and fish oil dietary levels
In the context of Mediterranean aquaculture little attention has been paid to
the manipulation of feeding frequency at the on-growing phase. The effects of
different feeding frequencies: one meal per day, two meals per day, three meals
per day on growth, digestive enzyme activity, feed digestibility and plasma
biochemistry were studied in gilthead sea bream (Sparus aurata, L. 1758) fed
with high and low fishmeal and fish oil levels. Isonitrogenous and isolipidic
extruded diets were fed to triplicate fish groups by a fixed ration over 109
days. No significant effects of feeding frequency on overall performance, feed
efficiency and feed digestibility during the on-growing of gilthead sea bream
fed high or low fishmeal and fish oil dietary level were observed. Pepsin
activity showed an apparent decrease in fish receiving more than one meal a day
which was not compensated by an increased production of alkaline proteases
particularly in fish fed on low FM. Although there were no effects on growth
and feed utilisation at increasing feeding frequency, trypsin decreased
significantly with an increasing number of meals only under low FMFO diet.
Thus, it seemed that consecutive meals could have amplified the potential
trypsin inhibitor effect of the vegetable meal-based diet adopted. Results of
the plasma parameters related to nutritional and physiological conditions were
not affected by feeding frequency. The higher level of plasma creatinine
detected in fish fed a single daily meal with high FMFO level seems to be
within physiological values in relation to the higher protein efficiency
observed with this diet. According to the results, gilthead sea bream seems
able to maximise feed utilisation regardless of the number of meals, and this
could be a useful indicator for planning feeding activity at farm level to
optimise growth of fish and costs of feeding procedures
Searching for Planets in the Hyades II: Some Implications of Stellar Magnetic Activity
The Hyades constitute a homogeneous sample of stars ideal for investigating
the dependence of planet formation on the mass of the central star. Due to
their youth, Hyades members are much more chromospherically active than stars
traditionally surveyed for planets using high precision radial velocity (RV)
techniques. Therefore, we have conducted a detailed investigation of whether
magnetic activity of our Hyades target stars will interfere with our ability to
make precise RV searches for substellar companions. We measure chromospheric
activity (which we take as a proxy for magnetic activity) by computing the
equivalent of the R'HK activity index from the Ca II K line. is not
constant in the Hyades: we confirm that it decreases with increasing
temperature in the F stars, and also find it decreases for stars cooler than
mid-K. We examine correlations between simultaneously measured R'HK and RV
using both a classical statistical test and a Bayesian odds ratio test. We find
that there is a significant correlation between R'HK and the RV in only 5 of
the 82 stars in this sample. Thus, simple Rprime HK-RV correlations will
generally not be effective in correcting the measured RV values for the effects
of magnetic activity in the Hyades. We argue that this implies long timescale
activity variations (of order a few years; i.e., magnetic cycles or growth and
decay of plage regions) will not significantly hinder our search for planets in
the Hyades if the stars are closely monitored for chromospheric activity. The
trends in the RV scatter (sigma'_v) with , vsini, and P_rot for our stars
is generally consistent with those found in field stars in the Lick planet
search data, with the notable exception of a shallower dependence of sigma'_v
on for F stars.Comment: 15 pages, 7 figures, 3 tables; To appear in the July 2002 issue of
The Astronomical Journa
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