600 research outputs found
Optical phase coherent timing of the Crab nebula pulsar with Iqueye at the ESO New Technology Telescope
The Crab nebula pulsar was observed in 2009 January and December with a novel
very fast optical photon counter, Iqueye, mounted at the ESO 3.5 m New
Technology Telescope. Thanks to the exquisite quality of the Iqueye data, we
computed accurate phase coherent timing solutions for the two observing runs
and over the entire year 2009. Our statistical uncertainty on the determination
of the phase of the main pulse and the rotational period of the pulsar for
short (a few days) time intervals are s and ~0.5 ps,
respectively. Comparison with the Jodrell Bank radio ephemerides shows that the
optical pulse leads the radio one by ~240 s in January and ~160 s in
December, in agreement with a number of other measurements performed after
1996. A third-order polynomial fit adequately describes the spin-down for the
2009 January plus December optical observations. The phase noise is consistent
with being Gaussian distributed with a dispersion of s in most observations, in agreement with theoretical expectations for
photon noise-induced phase variability.Comment: 10 pages, 5 figures. Accepted for publication in Monthly Notices of
the Royal Astronomical Societ
Aqueye+: a new ultrafast single photon counter for optical high time resolution astrophysics
Aqueye+ is a new ultrafast optical single photon counter, based on single
photon avalanche photodiodes (SPAD) and a 4-fold split-pupil concept. It is a
completely revisited version of its predecessor, Aqueye, successfully mounted
at the 182 cm Copernicus telescope in Asiago. Here we will present the new
technological features implemented on Aqueye+, namely a state of the art timing
system, a dedicated and optimized optical train, a high sensitivity and high
frame rate field camera and remote control, which will give Aqueye plus much
superior performances with respect to its predecessor, unparalleled by any
other existing fast photometer. The instrument will host also an optical
vorticity module to achieve high performance astronomical coronography and a
real time acquisition of atmospheric seeing unit. The present paper describes
the instrument and its first performances.Comment: Proceedings of the SPIE, Volume 9504, id. 95040C 14 pp. (2015
Use of natural extract of chestnut (Silvafeed ENC®) in broiler feeding: effect on growth performance
The aim of this research was to study the effect of addition of natural extract of chestnut (Castanea sativa) Silvafeed ENC® in commercial feed on the growth of broilers. Two hundred and four broiler chicks (Cobb 508) 14 d old male, were randomly assigned to 12 floor pens and fed commercial diet supplemented with 0% (CE0), 0.15% (CE15), 0.20% (CE20) and 0.25% (CE25) of ENC. The ENC addition showed a beneficial effect on weight increases daily feed intake (DFI) and average daily gain (ADG) from 14 to 35 days of age. In the second half of trial the effects were less evident and concluding with a detrimental effect in CE25 group. Feed conversion rate (FCR) appears to be statistically different in the second and fifth weeks of feeding. The inclusion of ENC at 0.20%, (CE20) had significant influences on final weight, DFI and ADG and a favourable influence on FCR in comparison with the other three groups. In conclusion, ENC has been shown to be beneficial at concentrations between 0.15% and 0.20%
Aqueye optical observations of the Crab Nebula pulsar
We observed the Crab pulsar in October 2008 at the Copernico Telescope in
Asiago - Cima Ekar with the optical photon counter Aqueye (the Asiago Quantum
Eye) which has the best temporal resolution and accuracy ever achieved in the
optical domain (hundreds of picoseconds). Our goal was to perform a detailed
analysis of the optical period and phase drift of the main peak of the Crab
pulsar and compare it with the Jodrell Bank ephemerides. We determined the
position of the main peak using the steepest zero of the cross-correlation
function between the pulsar signal and an accurate optical template. The pulsar
rotational period and period derivative have been measured with great accuracy
using observations covering only a 2 day time interval. The error on the period
is 1.7 ps, limited only by the statistical uncertainty. Both the rotational
frequency and its first derivative are in agreement with those from the Jodrell
Bank radio ephemerides archive. We also found evidence of the optical peak
leading the radio one by ~230 microseconds. The distribution of phase-residuals
of the whole dataset is slightly wider than that of a synthetic signal
generated as a sequence of pulses distributed in time with the probability
proportional to the pulse shape, such as the average count rate and background
level are those of the Crab pulsar observed with Aqueye. The counting
statistics and quality of the data allowed us to determine the pulsar period
and period derivative with great accuracy in 2 days only. The time of arrival
of the optical peak of the Crab pulsar leads the radio one in agreement with
what recently reported in the literature. The distribution of the phase
residuals can be approximated with a Gaussian and is consistent with being
completely caused by photon noise (for the best data sets).Comment: 7 pages, 7 figures. Accepted for publication in Astronomy and
Astrophysic
effects of a natural extract of chestnut wood on digestibility performance traits and nitrogen balance of broiler chicks
Currently, feed ingredients containing tannin are attracting more interest as substitutes for antibiotic growth promoters in animal and poultry feeding. This study investigated the influence of a natural extract of chestnut wood (Silvafeed ENC) on broiler digestibility (experiment 1) and on the growth performance, carcass quality, and nitrogen balance of broilers (experiment 2). Results showed that the inclusion of ENC did not influence the apparent digestibility of organic matter, CP, and ether extract. Chick growth performance showed a quadratic or cubic response with increasing levels of ENC. When chicks were fed ENC from 14 to 56 d of age, the ENC had a positive effect on average daily gain in the first 2 wk of addition, whereas this effect was not evident in the last 2 wk compared with the control group. Similar trends were also shown for daily feed intake. Overall, the chicks fed 0.20% ENC had significantly better growth performance than the control group. Carcass analysis showed no gross lesions in organs and no significant differences in thigh and breast composition among groups. Noteworthy is the fact that the ENC-treated groups had less total litter nitrogen; in particular, chicks fed 0.15 and 0.20% ENC showed a significant difference in total litter nitrogen compared with the control group. No significant difference in nitrogen balance was observed. Addition of 0.20% ENC seemed to have a positive influence on chick feeding
Heterozygous, Polyploid, Giant Bacterium, Achromatium, Possesses an Identical Functional Inventory Worldwide across Drastically Different Ecosystems
Achromatium is large, hyperpolyploid and the only known heterozygous bacterium. Single cells contain approximately 300 different chromosomes with allelic diversity far exceeding that typically harbored by single bacteria genera. Surveying all publicly available sediment sequence archives, we show that Achromatium is common worldwide, spanning temperature, salinity, pH, and depth ranges normally resulting in bacterial speciation. Although saline and freshwater Achromatium spp. appear phylogenetically separated, the genus Achromatium contains a globally identical, complete functional inventory regardless of habitat. Achromatium spp. cells from differing ecosystems (e.g., from freshwater to saline) are, unexpectedly, equally functionally equipped but differ in gene expression patterns by transcribing only relevant genes. We suggest that environmental adaptation occurs by increasing the copy number of relevant genes across the cell’s hundreds of chromosomes, without losing irrelevant ones, thus maintaining the ability to survive in any ecosystem type. The functional versatility of Achromatium and its genomic features reveal alternative genetic and evolutionary mechanisms, expanding our understanding of the role and evolution of polyploidy in bacteria while challenging the bacterial species concept and drivers of bacterial speciation
- …