208 research outputs found
Impact of soil management on the functional activity of microbial communities associated to cork oak rhizosphere
The microbial ecology of cork oak rhizosphere was investigated using the Biolog community level physiological profile (CLPP) that provides a unique metabolic fingerprint helpful for the characterization of complex microbial communities. Microbial populations from the rhizosphere of cork oak plants growing at three different sites within the same area were characterized using CLPP and compared. The sites were distinguished by a different soil management under the tree cover and, in general terms, by a different anthropogenic impact. The comparison of metabolic fingerprints of the different microbial populations showed the existence of a relationship between general microbial activity and functional biodiversity in the rhizosphere and the level of anthropogenic impact. Particularly the presence of grazing animals, soil tillage and fire could be identified as the main factors affecting both the general microbial activity and the structure of microbial populations from cork oak rhizospheres
Measurements with the ELI-NP cavity Beam Position Monitor Read-out Electronics at FLASH
The Extreme Light Infrastructure - Nuclear Physics
Gamma Beam System (ELI-NP GBS) will be installed and
commissioned starting within the next year in Magurele,
Romania. It will generate gamma beam through Compton
back-scattering of a recirculated laser and a multi-bunch
electron beam, produced by a 720 MeV LINAC. In order
to obtain bunch by bunch position measurements, four cavity
beam position monitors (cBPM) near the two interaction
points are foreseen. Extensive tests on the cBPM readout
electronics, recently developed by Instrumentation
Technologies and acquired for ELI-NP GBS, were performed
in laboratory at INFN-LNF and at FLASH in
DESY, during the user operation. In the latter case, three
cBPMs installed along the LINAC, with similar features as
the ones of ELI-NP GBS, were used as measuring devices
and signal sources for the read-out electronics under test.
We present here the measurements collected and the related
analysis, with a particular focus on the beam position
measurement resolution
Thermal simulations for optical transition radiation screen for Eli-NP compton gamma source
The ELI-NP GBS (Extreme Light Infrastructure-Nuclear Physics Gamma Beam Source) is a high brightness elec-tron LINAC that is being built in Romania. The goal for this facility is to provide high luminosity gamma beam through Compton Backscattering. A train of 32 bunches at 100Hz with a nominal charge of 250pC is accelerated up to 740 MeV. Two interaction points with an IR Laser beam produces the gamma beam at different energies. In order to measure the electron beam spot size and the beam proper-ties along the train, the OTR screens must sustain the ther-mal and mechanical stress due to the energy deposited by the bunches. This paper is an ANSYS study of the issues due to the high quantity of energy transferred to the OTR screen. They will be shown different analysis, steady-state and thermal transient analysis, where the input loads will be the internal heat generation equivalent to the average power, deposited by the ELI-GBS beam in 512 ns, that is the train duration. Each analyses will be followed by the structural analysis to investigate the performance of the OTR materi
Spot size measurements in the Eli-NP compton gamma source
A high brightness electron Linac is being built in the Compton Gamma Source at the ELI Nuclear Physics facility in Romania. To achieve the design luminosity, a train of 32 bunches with a nominal charge of 250 pC and 16 ns spacing , will collide with the laser beam in the interaction point. Electron beam spot size is measured with an OTR (optical transition radiation) profile moni-tors. In order to measure the beam properties, the optical radiation detecting system must have the necessary accu-racy and resolution. This paper deals with the studies of different optic configurations to achieve the magnifica-tion, resolution and accuracy desired considering design and technological constraints; we will compare several configurations of the optical detection line to justify the one chosen for the implementation in the Lina
Longitudinal and Transverse Wakefields Simulations and Studies in Dielectric-Coated Circular Waveguides
In recent years, there has been a growing interest and rapid experimental progress on the use of e.m. fields produced by electron beams passing through dielectric-lined structures and on the effects they might have on the drive and witness bunches. Short ultra-relativistic electron bunches can excite very intense wakefields, which provide an efficient acceleration through the dielectric wakefield accelerators (DWA) scheme with higher gradient than that in the conventional RF LINAC. These beams can also generate high power narrow band THz coherent Cherenkov radiation. These high gradient fields may create strong instabilities on the beam itself causing issues in plasma acceleration experiments (PWFA), plasma lensing experiments and in recent beam diagnostic applications. In this work we report the results of the simulations and studies of the wakefields generated by electron beams at different lengths and charges passing on and off axis in dielectric-coated circular waveguides. We also propose a semi-analytical method to calculate these high gradient fields without resorting to time consuming simulations
Optical issues for the diagnostic stations for the ELI-NP compton gamma source
A high brightness electron Linac is being built in the Compton Gamma Source at the ELI Nuclear Physics facility in Romania. To achieve the design luminosity, a train of 32 bunches, 16 ns spaced, with a nominal charge of 250 pC will collide with the laser beam in the interaction point. Electron beam spot size is measured with optical transition radiation (OTR) profile monitors. In order to measure the beam properties, the optical radiation detecting system must have the necessary accuracy and resolution. This paper deals with the studies of different optic configurations to achieve the magnification, resolution and accuracy in order to measure very small beam (below 30 μm) or to study the angular distribution of the OTR and therefore the energy of the beam. Several configurations of the optical detection line will be studied both with simulation tools (e.g. Zemax) and experimentally. The paper will deal also with the sensibility of optic system (in terms of depth of field, magnification and resolution) to systematic error
OTR based measurements for ELI-NP Gamma Beam Source
The Gamma Beam Source (ELI-NP-GBS) machine is an advanced source of up to ≈20 MeV Gamma Rays based on Compton back-scattering, i.e. collision
of an intense high power laser beam and a high brightness electron beam with maximum kinetic energy of about 720 MeV. The Linac will provide trains of
32 electron bunches in each RF pulse, separated by 16.1 ns; each bunch has a charge of 250 pC . The goal of my work is to propose a layout for a distributed energy measurement along the ELI-NP-GBS machine: this will be useful during the commissioning stage of the machine in order to verify the correct functionality of the newly design C-Band accelerating structures, due to the fact that there are OTR screens after each accelerating module. Furthermore, I have studied the feasibility of bunch by bunch energy measurement using a gated camera system
Improvement in Hemodynamic Responses to Metaboreflex Activation after One Year of Training in Spinal Cord Injured Humans
Spinal cord injured (SCI) individuals show an altered hemodynamic response to metaboreflex activation due to a reduced capacity to vasoconstrict the venous and arterial vessels below the level of the lesion. Exercise training was found to enhance circulating catecholamines and to improve cardiac preload and venous tone in response to exercise in SCI subjects. Therefore, training would result in enhanced diastolic function and capacity to vasoconstrict circulation. The aim of this study was to test the hypothesis that one year of training improves hemodynamic response to metaboreflex activation in these subjects. Nine SCI individuals were enrolled and underwent a metaboreflex activation test at the beginning of the study (T0) and after one year of training (T1). Hemodynamics were assessed by impedance cardiography and echocardiography at both T0 and T1. Results show that there was an increment in cardiac output response due to metaboreflex activity at T1 as compared to T0 (545.4 ± 683.9 mL · min(-1) versus 220.5 ± 745.4 mL · min(-1), P < 0.05). Moreover, ventricular filling rate response was higher at T1 than at T0. Similarly, end-diastolic volume response was increased after training. We concluded that a period of training can successfully improve hemodynamic response to muscle metaboreflex activation in SCI subjects
Analysis and Correction of Geometrical Non-Linearities of ELI-NP BPMs on Position and Current Measurements
The advanced source of Gamma-ray photons will be soon built near Bucharest (Romania) by an European consortium (EurogammaS) led by INFN, as part of the ELI-NP (Extreme Light Infrastructure-Nuclear Physics). It will generate photons by Compton back-scattering in the collision between a multi-bunch electron beam, at a maximum energy of 720 MeV, and a high intensity recirculated laser pulse. An S-Band photo-injector and the following C-band Linac, which are under construction, will operate at 100Hz repetition rate with macro pulses of 32 electron bunches, separated by 16ns and with 250pC nominal charge. Stripline and cavity BPMs will be installed along the linac, in order to measure both the position and charge of the electron beam. Stripline BPM response can be considered linear within a limited area around the BPM origin. In order to use the full BPM acceptance area, without accuracy losses due to non-linearities, we plan to use correction algorithms, developed on the basis of simulations and measurements of BPMs response. In particular, suitable high-order surface polynomials will be used
Diving response after a one-week diet and overnight fasting
Background: We hypothesized that overnight fasting after a short dietary period, especially with carbohydrates, could allow performing breath-hold diving with no restraint for diaphragm excursion and blood shift and without any increase of metabolism, and in turn improve the diving response.
Methods: During two separate sessions, 8 divers carried out two trials: (A) a 30-m depth dive, three hours after a normal breakfast and (B) a dive to the same depth, but after following a diet and fasting overnight. Each test consisted of 3 apnea phases: descent, static and ascent whose durations were measured by a standard chronometer. An impedance cardiograph, housed in an underwater torch, provided data on trans-thoracic fluid index (TFI), stroke volume (SV), heart rate (HR) and cardiac output (CO). Mean blood pressure (MBP), arterial O-2 saturation (SaO(2)), blood glucose (Glu) and blood lactate (BLa) were also collected.
Results: In condition B, duration of the static phase of the dive was longer than A (37.8 +/- 7.4 vs. 27.3 +/- 8.4 s respectively, P < 0.05). In static phases, mean Delta SV value (difference between basal and nadir values) during fasting was lower than breakfast one (-2.6 +/- 5.1 vs. 5.7 +/- 7.6 ml, P < 0.05). As a consequence, since mean. HR values were equally decreased in both metabolic conditions, mean. CO value during static after fasting was lower than the same phase after breakfast (-0.4 +/- 0.5 vs. 0.4 +/- 0.5 L . min(-1) respectively, P < 0.05). At emersion, despite the greater duration of dives during fasting, SaO(2) was higher than A (92.0 +/- 2.7 vs. 89.4 +/- 2.9 % respectively, P < 0.05) and BLa was lower in the same comparison (4.2 +/- 0.7 vs. 5.3 +/- 1.1 mmol L-1, P < 0.05).
Conclusions: An adequate balance between metabolic and splancnic status may improve the diving response during a dive at a depth of 30 m, in safe conditions for the athlete's healt
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