183 research outputs found
Procedura per la valutazione dell'emissione di campi EM da un apparato per ipetermia con componente diatermica a 434.0 MHz e verifica del rispetto degli standard
The objective of this technical report is to establish a measurement procedure and/or measurement protocol in order to characterize the electromagnetic, electric and/or magnetic field sources at the workplaces, particularly in hospitals and in medical environmental. In this particular cases the exposure to electromagnetic fields involve workers, in-patients and their parents, and the devices and medical equipments. For the workers case we refer on the D.Lgs 81/2008 which acknowledges the European Directive 2004/40/EC on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (electromagnetic fields). For the in-patients the risk-benefit evaluation for exposure to electromagnetic fields is to advantage of benefit, except particular situations. For the parents of the in-patients we apply the standard fixed by the italian law (DPCM 8 Luglio 2003 “Fissazione dei limiti di esposizione, dei valori di attenzione e degli obiettivi di qualità per la protezione della popolazione dalle esposizioni a campi elettrici, magnetici ed elettromagnetici generati a frequenze comprese fra 100 kHz e 300 GHz”) For the devices and the medical equipments we refer to the CEI EN 60601-1-2. The standard fixes the electromagnetic immunity limits to 10 V/m for life-supporting equipments and systems and to 3 V/m for no life-supporting equipments and systems An instrument device for hyperthermia (Delta, Easytech Srl) has been chose as case-study for test the proposed measurement procedure. This instrument device is used in medical environmental to treatment of the pathologies of the locomotor apparatus. Its operating frequency is in ISM band (433.05÷434.79 MHz)
The mystery of the 'Kite' radio source in Abell 2626: insights from new Chandra observations
We present the results of a new Chandra study of the galaxy cluster A2626.
The radio emission of the cluster shows a complex system of four symmetric arcs
without known correlations with the X-ray emission. The mirror symmetry of the
radio arcs toward the center and the presence of two optical cores in the
central galaxy suggested that they may be created by pairs of precessing radio
jets powered by dual AGNs inside the cD galaxy. However, previous observations
failed to observe the second jetted AGN and the spectral trend due to radiative
age along the radio arcs, thus challenging this interpretation. The new Chandra
observation had several scientific objectives, including the search for the
second AGN that would support the jet precession model. We focus here on the
detailed study of the local properties of the thermal and non-thermal emission
in the proximity of the radio arcs, in order to get more insights into their
origin. We performed a standard data reduction of the Chandra dataset deriving
the radial profiles of temperature, density, pressure and cooling time of the
intra-cluster medium. We further analyzed the 2D distribution of the gas
temperature, discovering that the south-western junction of the radio arcs
surrounds the cool core of the cluster. We studied the X-ray SB and spectral
profiles across the junction, finding a cold front spatially coincident with
the radio arcs. This may suggest a connection between the sloshing of the
thermal gas and the nature of the radio filaments, raising new scenarios for
their origin. A possibility is that the radio arcs trace the projection of a
complex surface connecting the sites where electrons are most efficiently
reaccelerated by the turbulence that is generated by the gas sloshing. In this
case, diffuse emission embedded by the arcs and with extremely steep spectrum
should be most visible at very low radio frequencies.Comment: 7 pages, 7 figures. Accepted for publication on A&
Procedura per la valutazione dell\u27emissione di campi EM da un apparato per ipetermia con componente diatermica a 434.0 MHz e verifica del rispetto degli standard
The objective of this technical report is to establish a measurement procedure and/or measurement protocol in order to characterize the electromagnetic, electric and/or magnetic field sources at the workplaces, particularly in hospitals and in medical environmental. In this particular cases the exposure to electromagnetic fields involve workers, in-patients and their parents, and the devices and medical equipments. For the workers case we refer on the D.Lgs 81/2008 which acknowledges the European Directive 2004/40/EC on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (electromagnetic fields). For the in-patients the risk-benefit evaluation for exposure to electromagnetic fields is to advantage of benefit, except particular situations. For the parents of the in-patients we apply the standard fixed by the italian law (DPCM 8 Luglio 2003 "Fissazione dei limiti di esposizione, dei valori di attenzione e degli obiettivi di qualit? per la protezione della popolazione dalle esposizioni a campi elettrici, magnetici ed elettromagnetici generati a frequenze comprese fra 100 kHz e 300 GHz") For the devices and the medical equipments we refer to the CEI EN 60601-1-2. The standard fixes the electromagnetic immunity limits to 10 V/m for life-supporting equipments and systems and to 3 V/m for no life-supporting equipments and systems An instrument device for hyperthermia (Delta, Easytech Srl) has been chose as case-study for test the proposed measurement procedure. This instrument device is used in medical environmental to treatment of the pathologies of the locomotor apparatus. Its operating frequency is in ISM band (433.05?434.79 MHz)
LoTSS jellyfish galaxies: II. Ram pressure stripping in groups versus clusters
Numerous examples of ram pressure stripping in galaxy clusters are present in
literature; however, substantially less work has been focused on ram pressure
stripping in lower mass groups. In this work we use the LOFAR Two-metre Sky
Survey (LoTSS) to search for jellyfish galaxies in ~500 SDSS groups (z<0.05),
making this the most comprehensive search for ram pressure stripping in groups
to date. We identify 60 jellyfish galaxies in groups with extended, asymmetric
radio continuum tails, which are found across the entire range of group mass
from . We
compare the group jellyfish galaxies identified in this work with the LoTSS
jellyfish galaxies in clusters presented in Roberts et al. (2021), allowing us
to compare the effects of ram pressure stripping across three decades in
group/cluster mass. We find that jellyfish galaxies are most commonly found in
clusters, with the frequency decreasing towards the lowest mass groups. Both
the orientation of observed radio continuum tails, and the positions of group
jellyfish galaxies in phase space, suggest that galaxies are stripped more
slowly in groups relative to clusters. Finally, we find that the star formation
rates of jellyfish galaxies in groups are consistent with `normal' star-forming
group galaxies, which is in contrast to cluster jellyfish galaxies that have
clearly enhanced star formation rates. On the whole, there is clear evidence
for ongoing ram pressure stripping in galaxy groups (down to very low group
masses), though the frequency of jellyfish galaxies and the strength of ram
pressure stripping appears smaller in groups than clusters. Differences in the
efficiency of ram pressure stripping in groups versus clusters likely
contributes to the positive trend between quenched fraction and host halo mass
observed in the local Universe.Comment: 10 pages, 7 figures, 1 appendix, accepted for publication in A&
Very Large Array observations of the mini-halo and AGN feedback in the Phoenix cluster
(Abridged) The relaxed cool-core Phoenix cluster (SPT-CL J2344-4243) features
an extremely strong cooling flow, as well as a mini-halo. Strong star-formation
in the brightest cluster galaxy indicates that AGN feedback has been unable to
inhibit this cooling flow. We have studied the strong cooling flow in the
Phoenix cluster by determining the radio properties of the AGN and its lobes.
In addition, we use spatially resolved observations to investigate the origin
of the mini-halo. We present new Very Large Array 1-12 GHz observations of the
Phoenix cluster which resolve the AGN and its lobes in all four frequency
bands, and resolve the mini-halo in L- and S-band. Using our L-band
observations, we measure the total flux density of the radio lobes at 1.5 GHz
to be mJy, and the flux density of the mini-halo to be
mJy. Using L- and X-band images, we produce the first spectral index maps of
the lobes from the AGN and measure the spectral indices of the northern and
southern lobes to be and , respectively.
Similarly, using L- and S-band data, we map the spectral index of the
mini-halo, and obtain an integrated spectral index of .
We find that the mini-halo is most likely formed by turbulent re-acceleration
powered by sloshing in the cool core due to a recent merger. In addition, we
find that the feedback in the Phoenix cluster is consistent with the picture
that stronger cooling flows are to be expected for massive clusters like the
Phoenix cluster, as these may feature an underweight supermassive black hole
due to their merging history. Strong time variability of the AGN on
Myr-timescales may help explain the disconnection between the radio and the
X-ray properties of the system. Finally, a small amount of jet precession
likely contributes to the relatively low ICM re-heating efficiency of the
mechanical feedback.Comment: 12 pages, 14 figures. Accepted for publication in A&
Valutazione del rischio elettromagnetico ai sensi del D.Lgs. 81/2008 presso l\u27Azienda Ospedaliera Mellino Mellini Chiari (Brescia)
.La relazione riferisce i risultati della campagna di misura effettuata nei giorni dal 6 al 9 giugno 2011 e successivamente il 4 e il 6 luglio 2011. La campagna ? stata preceduta da un sopralluogo (21 marzo 2011) alle strutture di competenza dell\u27Azienda Mellino Mellini (Chiari, Iseo, Rovato, Palazzolo ed Orzinuovi) per la definizione delle azioni da intraprendere per la valutazione del rischio elettromagnetico in conformit? al D.Lgs. 81/2008. Pi? specificatamente gli obiettivi della campagna di misura sono stati i seguenti. Misura dei campi elettromagnetici (EM) in punti predefiniti per la determinazione dei livelli di campo EM presenti. Determinazione dei campi elettrici, magnetici ed elettromagnetici emessi da apparecchiature elettromedicali quali magnetoterapia e radarterapia . Misura dei campi magnetici (in particolare induzione magnetica) presenti nei locali tecnici quali cabina elettrica e impianti di condizionamento. Valutazione dell\u27intensit? dell\u27induzione magnetica all\u27interno e in prossimit? di incubatrici e culle termiche (Chiari e Iseo). Valutazione delle specifiche tecniche di elettrobisturi (Blocco Operatorio di Iseo). Caratterizzazione della presenza di eventuali interferenze EM dovute alla rete wireless (reparto di terapia intensiva di cardiologia di Chiari) o da disturbi EM presenti su apparecchiature per diagnostica (neurologia di Chiari)
Radio continuum tails in ram pressure-stripped spiral galaxies: experimenting with a semi-empirical model in Abell 2255
Wide-field radio continuum observations of galaxy clusters are revealing an
increasing number of spiral galaxies hosting tens of kpc-long radio tails
produced by the nonthermal interstellar medium being displaced by the ram
pressure. We present a semi-empirical model for the multi-frequency radio
continuum emission from ram pressure stripped tails based on the pure
synchrotron cooling of a radio plasma moving along the stripping direction with
a uniform velocity. We combine LOFAR and uGMRT observations at 144 and 400 MHz
to study the flux density and spectral index profiles of the radio tails of 7
galaxies in Abell 2255, and use the model to reproduce the flux density and
spectral index profiles, and infer the stripped radio plasma velocity. For 5
out of 7 galaxies we observe monotonic decrease in both flux density and
spectral index up to kpc from their stellar disk. Our model reproduces
the observed trends with a radio plasma bulk projected velocity between 160 and
430 km s. This result represents the first indirect measure of the
stripped, nonthermal interstellar medium velocity. The observed spectral index
trends indicate that the synchrotron cooling is faster than the adiabatic
expansion losses, thus suggesting that the stripped radio plasma can survive
for a few tens of Myr outside of the stellar disk. This provides a lower limit
for the lifetime of the stripped ISM outside of the disk. As a proof of
concept, we use the best-fit velocities to constrain the galaxies' 3D velocity
in the cluster to be in the 300-1300 km s. We estimate the ram pressure
affecting these galaxies to be between 0.1 and 2.9 erg
cm, and measure the inclination between their stellar disk and the ram
pressure wind.Comment: 15 pages, 9 figures, 5 tables. Accepted for publication on A&A on May
31st 202
Two striking head-Tail galaxies in the galaxy cluster IIZW108: Insights into transition to turbulence, magnetic fields, and particle re-Acceleration
We present deep Jansky Very Large Array observations at 1.4 and 2.7 GHz (full polarization), as well as optical OmegaWINGS/WINGS and X-ray observations of two extended radio galaxies in the IIZW108 galaxy cluster at z = 0.04889. They show a bent tail morphology in agreement with a radio lobed galaxy falling into the cluster potential. Both galaxies are found to possess properties comparable with narrow-Angle tail galaxies in the literature even though they are part of a low mass cluster. We find a spectral index steepening and an increase in fractional polarization through the galaxy jets and an ordered magnetic field component mostly aligned with the jet direction. This is likely caused by either shear due to the velocity difference of the intracluster medium and the jet fluid and/or magnetic draping of the intracluster medium across the galaxy jets. We find clear evidence that one source is showing two active galactic nuclei (AGN) outbursts from which we expect the AGN has never turned off completely. We show that pure standard electron cooling cannot explain the jet length. We demonstrate therefore that these galaxies can be used as a laboratory to study gentle re-Acceleration of relativistic electrons in galaxy jets via transition from laminar to turbulent motion
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