3,740 research outputs found
Indagine esplorativa sui problemi e i bisogni delle famiglie di malati oncologici per migliorare l’assistenza, sia domiciliare sia in hospice
The objective of this study is to know what are the main difficulties that caregivers of cancer patients meet during the health care activity. With this aim in mind, an ad hoc questionnaire was built: the QATIP The questionnaire examines the emotions, needs and problems that the caregiver faces in helping a sick person. This study wished to provide initial input for reflection, focusing a proper attention to needs and problems faced by the figure of the caregive
A new Method to Constrain the Iron Abundance from Cooling Delays in Coronal Loops
Recent observations with TRACE reveal that the time delay between the
appearance of a cooling loop in different EUV temperature filters is
proportional to the loop length, dt_12 ~ L. We model this cooling delay in
terms of radiative loss and confirm this linear relationship theoretically. We
derive an expression that can be used to constrain the coronal iron enhancement
alpha_Fe=A_Fe^cor/A_Fe^Ph relative to the photospheric value as function of the
cooling delay dt_12, flux F_2, loop width w, and filling factor q_w < 1. With
this relation we find upper limits on the iron abundance enhancement of
alpha_Fe < 4.8+/-1.7 for 10 small-scale nanoflare loops, and alpha_Fe <
1.4+/-0.4 for 5 large-scale loops, in the temperature range of T~1.0-1.4 MK.
This result supports the previous finding that low-FIP elements, including Fe,
are enhanced in the corona. The same relation constitutes also a lower limit
for the filling factor, which is q_w > 0.2+/-0.1 and q_w > 0.8+/-0.2 for the
two groups of coronal loops.Comment: 2 Figure
Non-equilibrium of Ionization and the Detection of Hot Plasma in Nanoflare-heated Coronal Loops
Impulsive nanoflares are expected to transiently heat the plasma confined in
coronal loops to temperatures of the order of 10 MK. Such hot plasma is hardly
detected in quiet and active regions, outside flares. During rapid and short
heat pulses in rarified loops the plasma can be highly out of equilibrium of
ionization. Here we investigate the effects of the non-equilibrium of
ionization (NEI) on the detection of hot plasma in coronal loops.
Time-dependent loop hydrodynamic simulations are specifically devoted to this
task, including saturated thermal conduction, and coupled to the detailed
solution of the equations of ionization rate for several abundant elements. In
our simulations, initially cool and rarified magnetic flux tubes are heated to
10 MK by nanoflares deposited either at the footpoints or at the loop apex. We
test for different pulse durations, and find that, due to NEI effects, the loop
plasma may never be detected at temperatures above ~5 MK for heat pulses
shorter than about 1 min. We discuss some implications in the framework of
multi-stranded nanoflare-heated coronal loops.Comment: 22 pages, 7 figures, accepted for publicatio
Thermo-hydraulic Quench Propagation at the LHC Superconducting Magnet String
The superconducting magnets of the LHC are protected by heaters and cold by-pass diodes. If a magnet quenches, the heaters on this magnet are fired and the magnet chain is de-excited in about two minu tes by opening dump switches in parallel to a resistor. During the time required for the discharge, adjacent magnets might quench due to thermo-hydraulic propagation in the helium bath and/or heat con duction via the bus bar. The number of quenching magnets depends on the mechanisms for the propagation. In this paper we report on quench propagation experiments from a dipole magnet to an adjacent ma gnet. The mechanism for the propagation is hot helium gas expelled from the first quenching magnet. The propagation changes with the pressure opening settings of the quench relief valves
Fast Time Structure During Transient Microwave Brightenings: Evidence for Nonthermal Processes
Transient microwave brightenings (TMBs) are small-scale energy releases from
the periphery of sunspot umbrae, with a flux density two orders of magnitude
smaller than that from a typical flare. Gopalswamy et al (1994) first reported
the detection of the TMBs and it was pointed out that the radio emission
implied a region of very high magnetic field so that the emission mechanism has
to be gyroresonance or nonthermal gyrosynchrotron, but not free-free emission.
It was not possible to decide between gyroresonance and gyrosynchrotron
processes because of the low time resolution (30 s) used in the data analysis.
We have since performed a detailed analysis of the Very Large Array data with
full time resolution (3.3 s) at two wavelengths (2 and 3.6 cm) and we can now
adequately address the question of the emission mechanism of the TMBs. We find
that nonthermal processes indeed take place during the TMBs. We present
evidence for nonthermal emission in the form of temporal and spatial structure
of the TMBs. The fast time structure cannot be explained by a thermodynamic
cooling time and therefore requires a nonthermal process. Using the physical
parameters obtained from X-ray and radio observations, we determine the
magnetic field parameters of the loop and estimate the energy released during
the TMBs. The impulsive components of TMBs imply an energy release rate of 1.3
x 10^22 erg/s so that the thermal energy content of the TMBs could be less than
10^24 erg.Comment: 15 pages (Latex), 4 figures (eps). ApJ Letters in press (1997
Laboratory Experiments on Long Waves Interacting with Rigid Vertical Cylinders
The impact of waves caused by storm surges or floods could lead to significant damage to marine and fluvial structures. Hydraulic forces add significant hydrodynamic loads on bridges built in coastal and fluvial environments; therefore, the effect of the wave impact on bridge substructures must be properly considered for the safe and cost-effective design of the piers. The use of laboratory-scale models is a direct approach to investigate the effects of long waves on simple structures, mimicking bridge piers. The present study describes a laboratory-scale model, where the propagation of two different long waves in a flume, in the presence of two rigid cylinders, was investigated. The velocity measurements were acquired by the Particle Image Velocimetry (PIV) technique, providing instantaneous flow velocity vectors on 2D planes. For each experimental condition, the instantaneous velocity field close to the cylinders was analysed, in order i) to depict how it changes during the wave transit, and thus how the drag force acting on the cylinders could change, ii) to detect the spatial distributions of vorticity downstream. Some first interesting results have been obtained, showing a quite uniform distribution of the longitudinal velocity along the depth of the vertical plane upstream of the cylinders, with increasing values during the wave transit. No interactions in the central part of the flow downstream of the two cylinders was observed in the horizontal plane which are spaced approximately ten times their diameter. Finally, the vorticity has also been studied, displaying a phase-varying behaviour, which appears to lose symmetry during wave transit
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