94 research outputs found
Maternal and Neonatal Behaviour in Italian Mediterranean Buffaloes
The aim of this study was to describe the neonatal and maternal behaviour of Italian Mediterranean buffaloes. Thirty primiparous buffaloes were moved into individual pens 12.5 (±2.5) days before
calving. Maternal and neonatal behaviours were recorded for 48 h after calving and the analysis was
performed in continuous sampling with the software BORIS. Calvesâ clinical evaluations (temperature,
weight, and heart and respiratory rates) were performed at different time intervals and correlated with
behavioural data from the dam. Data were analysed with parametric and non-parametric methods after
controlling their distribution. The maternal behavioural pattern found highlighted buffaloesâ priorities
during the post-partum period: firstly, they stand and start grooming to ensure proper care for the calf; it
is only after this that they dedicate time to maintenance behaviours (feeding and lying). The dams mainly
groomed the calf during the first six hours after calving (average time in the 1â6-h interval: 7.7 ± 2.5 min.,
F = (2.5, 60.2) = 75.0; p < 0.001) to ensure the formation of the motherâinfant bond; thereafter, the behaviour
decreased over time. As reported in the literature, inexperienced mothers could sometimes delay the
calfâs first suckling with aggressive or rejection behaviours. In this regard, 16 buffalo dams showed at
least one maternal rejection behaviour, which was found to negatively correlate with calvesâ daily weight
gain (DWG) at 14 (rs = â0.5, p = 0.02) and 21 days (rs = â0.7, p < 0.001). The calves took on average
212.0 ± 110.0 min to suckle, and this behaviour was mainly shown during the first six hours. Overall,
suckling behaviour was correlated with standing: (rs = 0.6, p < 0.001) and walking (rs = 0.9, p < 0.001).
The calvesâ live weight and DWG were consistently higher than the values reported in the literature.
Our results present a detailed description of maternal and neonatal behaviour in the early post-partum
period in Italian Mediterranean buffaloes. We also found that maternal rejection behaviours can negatively
influence the calvesâ growth. Finally, we think that such results can improve the management of buffaloes
during the period around parturition
Phase transitions and He-synthesis driven winds in neutrino cooled accretion disks: prospects for late flares in short gamma-ray bursts
We consider the long term evolution of debris following the tidal disruption
of compact stars in the context of short gamma ray bursts (SGRBs). The initial
encounter impulsively creates a hot, dense, neutrino-cooled disk capable of
powering the prompt emission. After a long delay, we find that powerful winds
are launched from the surface of the disk, driven by the recombination of free
nucleons into alpha particles. The associated energy release depletes the mass
supply and eventually shuts off activity of the central engine. As a result,
the luminosity and mass accretion rate deviate from the earlier self-similar
behavior expected for an isolated ring with efficient cooling. This then
enables a secondary episode of delayed activity to become prominent as an
observable signature, when material in the tidal tails produced by the initial
encounter returns to the vicinity of the central object. The time scale of the
new accretion event can reach tens of seconds to minutes, depending on the
details of the system. The associated energies and time scales are consistent
with those occurring in X-ray flares.Comment: Revised version, accepted for publication in ApJ Letter
Evaluation of Sheep Anticipatory Response to a Food Reward by Means of Functional Near-Infrared Spectroscopy
Anticipatory behaviour to an oncoming food reward can be triggered via classical conditioning, implies the activation of neural networks, and may serve to study the emotional state of animals. The aim of this study was to investigate how the anticipatory response to a food reward affects the cerebral cortex activity in sheep. Eight ewes from the same flock were trained to associate a neutral auditory stimulus (water bubble) to the presence of a food reward (maize grains). Once conditioned, sheep were trained to wait 15 s behind a gate before accessing a bucket with food (anticipation phase). For 6 days, sheep were submitted to two sessions of six consecutive trials each. Behavioural reaction was filmed and changes in cortical oxy- and deoxy-hemoglobin concentration ([ÎO2Hb] and [ÎHHb] respectively) following neuronal activation were recorded by functional near infrared spectroscopy (fNIRS). Compared to baseline, during the anticipation phase sheep increased their active behaviour, kept the head oriented to the gate (Wilcoxonâs signed rank test; p †0.001), and showed more asymmetric ear posture (Wilcoxonâs signed rank test; p †0.01), most likely reflecting a learnt association and an increased arousal. Results of trial-averaged [ÎO2Hb] and [ÎHHb] within individual sheep showed in almost every sheep a cortical activation during the anticipation phase (Student T-test; p †0.05). The sheep showed a greater response of the right hemisphere compared to the left hemisphere, possibly indicating a negative affective state, such as frustration. Behavioural and cortical changes observed during anticipation of a food reward reflect a learnt association and an increased arousal, but no clear emotional valence of the sheep subjective experience. Future work should take into consideration possible factors affecting the accurateness of measures, such as probeâs location and scalp vascularization
The Free and Cued Selective Reminding Test: Discriminative Values in a Naturalistic Cohort
Background: Neuropsychological assessment is still the basis for the first evaluation of patients with cognitive complaints. The Free and Cued Selective Reminding Test (FCSRT) generates several indices that could have different accuracy in the differential diagnosis between Alzheimer's disease (AD) and other disorders. Objective: In a consecutive series of naturalistic patients, the accuracy of the FCSRT indices in differentiating patients with either mild cognitive impairment (MCI) due to AD or AD dementia from other competing conditions was evaluated. Methods: We evaluated the accuracy of the seven FCSRT indices in differentiating patients with AD from other competing conditions in 434 consecutive outpatients, either at the MCI or at the early dementia stage. We analyzed these data through the receiver operating characteristics curve, and we then generated the odds-ratio map of the two indices with the best discriminative value between pairs of disorders. Results: The immediate and the delayed free total recall, the immediate total recall, and the index of sensitivity of cueing were the most useful indices and allowed to distinguish AD from dementia with Lewy bodies and psychiatric conditions with very high accuracy. Accuracy was instead moderate in distinguishing AD from behavioral variant frontotemporal dementia, vascular cognitive impairment, and other conditions. Conclusion: By using odd-ratio maps and comparison-customized cut-off scores, we confirmed that the FCSRT represents a useful tool to characterize the memory performance of patients with MCI and thus to assist the clinician in the diagnosis process, though with different accuracy values depending on the clinical hypothesis
Gamma Ray Bursts Flares detected and observed by the Swift Satellite
The detection of flares with the Swift satellite triggered a lot of
bservational and theoretical interest in these phenomena. As a consequence a
large analysis effort started within the community to characterize the
phenomenon and at the same time a variety of theoretical speculations have been
proposed to explain it. In this presentation we discuss part of the results we
obtained analyzing a first statistical sample of GRBs observed with Swift. The
first goal of this research is very simple: derive those observational
properties that could distinguish between internal and external shock and
between an ever active central engine and delayed shocks (refreshing) related
to a very small initial Lorentz bulk factor. We discuss first the method of
analysis and the morphology evidencing the similarities such flares have with
the prompt emission pulses. We conclude that GRB flares are due to internal
shocks and leave still open the question of whether or not the central engine
is active for a time of the order of 105 seconds after the prompt emission.Comment: Proceedings of the Beijing COSPAR Assembly 2006; submitted Nov 2,
200
Swift XRT Observations of the Afterglow of XRF 050416A
Swift discovered XRF 050416A with the BAT and began observing it with its
narrow field instruments only 64.5 s after the burst onset. Its very soft
spectrum classifies this event as an X-ray flash. The afterglow X-ray emission
was monitored up to 74 days after the burst. The X-ray light curve initially
decays very fast, subsequently flattens and eventually steepens again, similar
to many X-ray afterglows. The first and second phases end about 172 and 1450 s
after the burst onset, respectively. We find evidence of spectral evolution
from a softer emission with photon index Gamma ~ 3.0 during the initial steep
decay, to a harder emission with Gamma ~ 2.0 during the following evolutionary
phases. The spectra show intrinsic absorption in the host galaxy. The
consistency of the initial photon index with the high energy BAT photon index
suggests that the initial phase of the X-ray light curve may be the low-energy
tail of the prompt emission. The lack of jet break signatures in the X-ray
afterglow light curve is not consistent with empirical relations between the
source rest-frame peak energy and the collimation-corrected energy of the
burst. The standard uniform jet model can give a possible description of the
XRF 050416A X-ray afterglow for an opening angle larger than a few tens of
degrees, although numerical simulations show that the late time decay is
slightly flatter than expected from on-axis viewing of a uniform jet. A
structured Gaussian-type jet model with uniform Lorentz factor distribution and
viewing angle outside the Gaussian core is another possibility, although a full
agreement with data is not achieved with the numerical models explored.Comment: Accepted for publication on ApJ; replaced with revised version: part
of the discussion moved in an appendix; 11 pages, 6 figures; abstract
shortened for posting on astro-p
A Comprehensive Analysis of Fermi Gamma-ray Burst Data: III. Energy-Dependent T90 Distributions of GBM GRBs and Instrumental Selection Effect on Duration Classification
The durations (T90) of 315 GRBs detected with Fermi/GBM (8-1000 keV) by 2011
September are calculated using the Bayesian Block method. We compare the T90
distributions between this sample and those derived from previous/current GRB
missions. We show that the T90 distribution of this GRB sample is bimodal, with
a statistical significance level being comparable to those derived from the
BeppoSAX/GRBM sample and the Swift/BAT sample, but lower than that derived from
the CGRO/BATSE sample. The short-to-long GRB number ratio is also much lower
than that derived from the BATSE sample, i.e., 1:6.5 vs 1:3. We measure T90 in
several bands, i.e., 8-15, 15-25, 25-50, 50-100, 100-350, and 350-1000 keV, to
investigate the energy-dependence effect of the bimodal T90 distribution. It is
found that the bimodal feature is well observed in the 50-100 and 100-350 keV
bands, but is only marginally acceptable in the 25-50 keV and 350-1000 keV
bands. The hypothesis of the bimodality is confidently rejected in the 8-15 and
15-25 keV bands. The T90 distributions in these bands are roughly consistent
with those observed by missions with similar energy bands. The parameter T90 as
a function of energy follows \bar T90 \propto E^{-0.20\pm 0.02} for long GRBs.
Considering the erratic X-ray and optical flares, the duration of a burst would
be even much longer for most GRBs. Our results, together with the observed
extended emission of some short GRBs, indicate that the central engine activity
time scale would be much longer than T90} for both long and short GRBs and the
observed bimodal T90 distribution may be due to an instrumental selection
effect.Comment: 29 pages, 2 tables, 9 figures, accepted for publication in Ap
A Comprehensive Study of Gamma-Ray Burst Optical Emission: I. Flares and Early Shallow Decay Component
Well-sampled optical lightcurves of 146 gamma-ray bursts (GRBs) are compiled
from the literature. By empirical fitting we identify eight possible emission
components and summarize the results in a "synthetic" lightcurve. Both optical
flare and early shallow-decay components are likely related to long-term
central engine activities. We focus on their statistical properties in this
paper. Twenty-four optical flares are obtained from 19 GRBs. The isotropic
R-band energy is smaller than 1% of . The relation between
isotropic luminosities of the flares and gamma-rays follows . Later flares tend to be
wider and dimmer, i.e., and . The detection
probability of the optical flares is much smaller than that of X-ray flares. An
optical shallow decay segment is observed in 39 GRBs. The relation between the
break time and break luminosity is a power-law, with an index of , similar to that derived from X-ray flares. The X-ray and optical breaks
are usually chromatic, but a tentative correlation is found. We suggest that
similar to the prompt optical emission that tracks -rays, the optical
flares are also related to the erratic behavior of the central engine. The
shallow decay component is likely related to a long-lasting spinning-down
central engine or piling up of flare materials onto the blastwave. Mixing of
different emission components may be the reason of the diverse chromatic
afterglow behaviors.Comment: 43 pages, 13 figures, 3 tables, accepted for publication in Ap
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