73 research outputs found
Rumen fluid, a new diagnostic matrix in dairy cattle farms?
Production diseases of dairy cows are considered man-made problems caused by the inability of cowsto achieve a sufficient feed energy intake (Mulligan, 2008).A correct management of production diseases demands early diagnostic and prognostic parameters, inorder to improve the management system and reduce the prevalence of clinical cases (Ingvartsen,2003).A previous study of our group indicated that forestomachs walls express immune receptors andcytokines, and the rumen liquor contains leukocytes able to produce IFN-γ (Trevisi, 2014).Our working hypothesis implied that ruminal fluids could be a source of diagnostic information for theidentification of herds at risk for production diseases.We first demonstrated that the diet can influence the immune response in forestomachs. Diverseleukocyte populations at low concentrations and IFN-γ were revealed in some samples of rumen fluids,with a clear inhibition of the response observed in the animals fed the maize-supplemented diet,compared to a normal and a soy-supplemented diet.We better characterized the leukocytes subpopulations in the rumen liquor, isolating B cells, monocytesand γδT cells.Finally we performed a field survey in order to find correlation among the immune profile of the rumenliquor. Clinically healthy animals showed a farm specific immunologic pattern of the rumen liquor: lowCD45 mRNA expression, low IFN-γ, few/absent B-cells.We can conclude that the epithelial cells of ruminant forestomachs can react to different stresses(metabolic, infectious, inflammatory) and the inflammatory response can be sustained by infiltratingleukocytes.Our data points into the idea that dairy farms could be ranked according to a risk score using theinflammatory markers in rumen fluids, in addition to the traditional analysis.
The Gas Pixel Detector as an X-ray photoelectric polarimeter with a large field of view
The Gas Pixel Detector (GPD) is a new generation device which, thanks to its
50 um pixels, is capable of imaging the photoelectrons tracks produced by
photoelectric absorption in a gas. Since the direction of emission of the
photoelectrons is strongly correlated with the direction of polarization of the
absorbed photons, this device has been proposed as a polarimeter for the study
of astrophysical sources, with a sensitivity far higher than the instruments
flown to date. The GPD has been always regarded as a focal plane instrument and
then it has been proposed to be included on the next generation space-borne
missions together with a grazing incidence optics. Instead in this paper we
explore the feasibility of a new kind of application of the GPD and of the
photoelectric polarimeters in general, i.e. an instrument with a large field of
view. By means of an analytical treatment and measurements, we verify if it is
possible to preserve the sensitivity to the polarization for inclined beams,
opening the way for the measurement of X-ray polarization for transient
astrophysical sources. While severe systematic effects arise for inclination
greater than about 20 degrees, methods and algorithms to control them are
discussed.Comment: 11 pages, 8 figure
An X-ray Polarimeter for HXMT Mission
The development of micropixel gas detectors, capable to image tracks produced
in a gas by photoelectrons, makes possible to perform polarimetry of X-ray
celestial sources in the focus of grazing incidence X-ray telescopes. HXMT is a
mission by the Chinese Space Agency aimed to survey the Hard X-ray Sky with
Phoswich detectors, by exploitation of the direct demodulation technique. Since
a fraction of the HXMT time will be spent on dedicated pointing of particular
sources, it could host, with moderate additional resources a pair of X-ray
telescopes, each with a photoelectric X-ray polarimeter in the focal plane. We
present the design of the telescopes and the focal plane instrumentation and
discuss the performance of this instrument to detect the degree and angle of
linear polarization of some representative sources. Notwithstanding the limited
resources the proposed instrument can represent a breakthrough in X-ray
Polarimetry.Comment: 10 pages, 9 figure
Monensin controlled-release capsule administered in late-pregnancy differentially affects rumination patterns, metabolic status, and cheese-making properties of the milk in primiparous and multiparous cows
The increased resistance to disease observed after monensin treatment could reflect a reduction of inflammation and oxidative stress. We hypothesised that if monensin supplementation was given before calving, it would help in controlling inflammation, reduce the susceptibility to disease and increase the performance. Fourteen pregnant heifers (PR) and 24 multiparous cows (ML) were randomly assigned to a treated group (Mon) or a control group (Ctr). The Mon group received 32.4 g of monensin in a controlled-release capsule 21 days before calving (expected release rate, 335 mg/d for 95 days). Their health status, rumination activity, and plasma parameters were monitored from –28 to 56 days from calving. The milk yield (MY), milk composition, and cheese-making properties were also monitored. Rumen samples were collected at 30 days from calving to assess the volatile fatty acids composition and investigate immunological parameters. After calving, the Mon group had fewer clinical diseases, an increased rumination time, and a higher MY. Monensin reduced the infiltration of both T and B cells in rumen fluid. In ML, the Mon group had lower levels of β-hydroxybutyrate in the early postpartum period and a lower level of total reactive oxygen species. Of PR, the Mon group had a tendency for lower levels of nonesterified fatty acids, higher levels of ceruloplasmin after the first month of lactation, a tendency for lower levels of paraoxonase, higher levels of γ-glutamyl transferase and higher levels of total reactive oxygen species. Monensin treatment decreased the cheese-making properties in the milk of PR.HighlightsMonensin improved the performance of all the animals and decreased the disease incidence in all of them.Monensin heightened the inflammatory and oxidative stress status and reduced the cheese-making properties in pregnant heifers.Although different effects were seen in cows with different parity, dairy cows generally beneficed of monensin administration. Monensin improved the performance of all the animals and decreased the disease incidence in all of them. Monensin heightened the inflammatory and oxidative stress status and reduced the cheese-making properties in pregnant heifers. Although different effects were seen in cows with different parity, dairy cows generally beneficed of monensin administration
Measurement of the position resolution of the Gas Pixel Detector
The Gas Pixel Detector was designed and built as a focal plane instrument for
X-ray polarimetry of celestial sources, the last unexplored subtopics of X-ray
astronomy. It promises to perform detailed and sensitive measurements resolving
extended sources and detecting polarization in faint sources in crowded fields
at the focus of telescopes of good angular resolution. Its polarimetric and
spectral capability were already studied in earlier works. Here we investigate
for the first time, with both laboratory measurements and Monte Carlo
simulations, its imaging properties to confirm its unique capability to carry
out imaging spectral-polarimetry in future X-ray missions.Comment: Submitted to Nuclear Instruments and Methods in Physics Research
Section A; 15 figures, 3 table
LAMP: a micro-satellite based soft X-ray polarimeter for astrophysics
The Lightweight Asymmetry and Magnetism Probe (LAMP) is a micro-satellite
mission concept dedicated for astronomical X-ray polarimetry and is currently
under early phase study. It consists of segmented paraboloidal multilayer
mirrors with a collecting area of about 1300 cm^2 to reflect and focus 250 eV
X-rays, which will be detected by position sensitive detectors at the focal
plane. The primary targets of LAMP include the thermal emission from the
surface of pulsars and synchrotron emission produced by relativistic jets in
blazars. With the expected sensitivity, it will allow us to detect polarization
or place a tight upper limit for about 10 pulsars and 20 blazars. In addition
to measuring magnetic structures in these objects, LAMP will also enable us to
discover bare quark stars if they exist, whose thermal emission is expected to
be zero polarized, while the thermal emission from neutron stars is believed to
be highly polarized due to plasma polarization and the quantum electrodynamics
(QED) effect. Here we present an overview of the mission concept, its science
objectives and simulated observational results
Re-testing the JET-X Flight Module No. 2 at the PANTER facility
The Joint European X-ray Telescope (JET-X) was the core instrument of the
Russian Spectrum-X-gamma space observatory. It consisted of two identical soft
X-ray (0.3 - 10 keV) telescopes with focusing optical modules having a measured
angular resolution of nearly 15 arcsec. Soon after the payload completion, the
mission was cancelled and the two optical flight modules (FM) were brought to
the Brera Astronomical Observatory where they had been manufactured. After 16
years of storage, we have utilized the JET-X FM2 to test at the PANTER X-ray
facility a prototype of a novel X-ray polarimetric telescope, using a Gas Pixel
Detector (GPD) with polarimetric capabilities in the focal plane of the FM2.
The GPD was developed by a collaboration between INFN-Pisa and INAF-IAPS. In
the first phase of the test campaign, we have re-tested the FM2 at PANTER to
have an up-to-date characterization in terms of angular resolution and
effective area, while in the second part of the test the GPD has been placed in
the focal plane of the FM2. In this paper we report the results of the tests of
the sole FM2, using an unpolarized X-ray source, comparing the results with the
calibration done in 1996.Comment: Author's accepted manuscript posted to arXiv.org as permitted by
Springer's Self-Archiving Policy. The final publication is available at
http://rd.springer.com/article/10.1007%2Fs10686-013-9365-
PolarLight: a CubeSat X-ray Polarimeter based on the Gas Pixel Detector
The gas pixel detector (GPD) is designed and developed for high-sensitivity
astronomical X-ray polarimetry, which is a new window about to open in a few
years. Due to the small mass, low power, and compact geometry of the GPD, we
propose a CubeSat mission Polarimeter Light (PolarLight) to demonstrate and
test the technology directly in space. There is no optics but a collimator to
constrain the field of view to 2.3 degrees. Filled with pure dimethyl ether
(DME) at 0.8 atm and sealed by a beryllium window of 100 micron thick, with a
sensitive area of about 1.4 mm by 1.4 mm, PolarLight allows us to observe the
brightest X-ray sources on the sky, with a count rate of, e.g., ~0.2 counts/s
from the Crab nebula. The PolarLight is 1U in size and mounted in a 6U CubeSat,
which was launched into a low Earth Sun-synchronous orbit on October 29, 2018,
and is currently under test. More launches with improved designs are planned in
2019. These tests will help increase the technology readiness for future
missions such as the enhanced X-ray Timing and Polarimetry (eXTP), better
understand the orbital background, and may help constrain the physics with
observations of the brightest objects.Comment: Accepted for publication in Experimental Astronom
Gas pixel detectors
Abstract With the Gas Pixel Detector (GPD), the class of micro-pattern gas detectors has reached a complete integration between the gas amplification structure and the read-out electronics. To obtain this goal, three generations of application-specific integrated circuit of increased complexity and improved functionality has been designed and fabricated in deep sub-micron CMOS technology. This implementation has allowed manufacturing a monolithic device, which realizes, at the same time, the pixelized charge-collecting electrode and the amplifying, shaping and charge measuring front-end electronics of a GPD. A big step forward in terms of size and performances has been obtained in the last version of the 0.18 μm CMOS analog chip, where over a large active area of 15×15 mm 2 a very high channel density (470 pixels/mm 2 ) has been reached. On the top metal layer of the chip, 105,600 hexagonal pixels at 50 μm pitch have been patterned. The chip has customable self-trigger capability and includes a signal pre-processing function for the automatic localization of the event coordinates. In this way, by limiting the output signal to only those pixels belonging to the region of interest, it is possible to reduce significantly the read-out time and data volume. In-depth tests performed on a GPD built up by coupling this device to a fine pitch (50 μm) gas electron multiplier are reported. Matching of the gas amplification and read-out pitch has let to obtain optimal results. A possible application of this detector for X-ray polarimetry of astronomical sources is discussed
X-ray polarimetry on-board HXMT
The development of micropixel gas detectors, capable to image tracks produced
in a gas by photoelectrons, makes possible to perform polarimetry of X-ray
celestial sources in the focus of grazing incidence X-ray telescopes. HXMT is a
mission by the Chinese Space Agency aimed to survey the Hard X-ray Sky with
Phoswich detectors, by exploitation of the direct demodulation technique. Since
a fraction of the HXMT time will be spent on dedicated pointing of particular
sources, it could host, with moderate additional resources a pair of X-ray
telescopes, each with a photoelectric X-ray polarimeter (EXP2, Efficient X-ray
Photoelectric Polarimeter) in the focal plane. We present the design of the
telescopes and the focal plane instrumentation and discuss the performance of
this instrument to detect the degree and angle of linear polarization of some
representative sources. Notwithstanding the limited resources, the proposed
instrument can represent a breakthrough in X-ray Polarimetry.Comment: 10 pages, 7 figure
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