...standardization of VANA is a fundamental principle behind EFFi. The exact value chosen for VANA appears not to be critical. ...a moderate error in flow sensor calibration is of low importance. In ...future studies, EFFi should be compared with alternative parameters (e.g., VAE/VT proposed by Lucangelo and colleagues 10). Because EFFi and VDphys/VT reflect uneven V : /Q : among lung compartments, it was expected that they correlate closely.
Experimental studies of light dripline nuclei are reviewed. Progress in the production of very short lived nuclei and the development of radioactive nuclear beams has given this field the necessary ...tools for detailed studies of the most exotic nuclei. A well-known feature for some of the light dripline nuclei is that under certain circumstances they may form a neutron or a proton halo with a dilute mass distribution extending far outside the core of the nucleus. The first observation of halo states was made in the middle of the 1980s and it generated an interest in dripline physics, both experimentally and theoretically, that has gone far beyond the study of halo states. The experimental results for halo states are starting to give a fairly complete understanding of their structure in many cases. The data include masses, spins, moments, reaction data over a wide energy range and beta-decays. There are two main classes of halo state: the two-body halos with one nucleon surrounding the core, like the one-neutron halos
11
Be
and
19
C
and the one-proton halo
8
B
; and the Borromean three-body halos with two valence nucleons around the core, the key examples being
6
He
,
11
Li
and
14
Be
. Experimental information about systems lying just outside the dripline play an important rôle in understanding the structure of the halo states, examples being
10
Li
and
13
Be
, which form two-body subsystems of
11
Li
and
14
Be
, respectively. Unbound resonance states that correspond to exotic unbound quantum systems like
5
H
,
7
H
and
9
He
have been identified. There are continuum states existing above the particle separation threshold as well as spectra indicating cluster or molecular structure. The traditional magic numbers valid for more stable nuclei have been found to disappear and be replaced with new ones in the dripline regions. The beta-decays in these regions may give access to halos in excited states and the associated beta-delayed particle decay modes provide information about coupling to the continuum.
After a short historical overview, examples on the most recent experimental results from this rapidly growing field of nuclear physics will be given.
Letter to editor Bajc Marika; Jonson Björn
European journal of nuclear medicine and molecular imaging,
07/2020, Letnik:
47, Številka:
7
Journal Article
Letter to editor Bajc, Marika; Jonson, Björn
European journal of nuclear medicine and molecular imaging,
07/2020, Letnik:
47, Številka:
7
Journal Article
Exotic Nuclei Jonson, Björn
Herald of the Russian Academy of Sciences,
05/2019, Letnik:
89, Številka:
3
Journal Article
The paper is dedicated to a very interesting and rapidly developing field of nuclear physics—the generation and study of exotic nuclei in the vicinity of the driplines. The history of this field is ...presented with methods of obtaining such nuclei in the accelerators of the world’s leading research centers—the European Organization for Nuclear Research (CERN) in Switzerland and the Helmholtz Center for Heavy Ion Research (GSI) in Germany. The structure of the nuclei, as they change greatly approaching the driplines of neutron and proton stability, is given, as well as the results of experimental research of neutron- and proton-rich nuclei and the formation of neutron halos in isotopes of helium, lithium, beryllium, and boron, strongly enriched with neutrons. Information on medical applications of radionuclide beams is presented.
Letter to editor Bajc, Marika; Jonson, Björn
European journal of nuclear medicine and molecular imaging,
2020/7, Letnik:
47, Številka:
7
Journal Article
Both reduction in tidal volume (VT) and alveolar recruitment may be important to limit ventilator-associated lung injury during mechanical ventilation of patients with the acute respiratory distress ...syndrome (ARDS). The aim of this study was to assess the risk of alveolar derecruitment associated with VT reduction from 10 to 6 ml/kg. Whether this VT-related derecruitment could be reversed, either by a recruitment maneuver or by an increase in positive end-expiratory pressure (PEEP) level, was also investigated. Fifteen patients with ARDS were successively ventilated using conventional VT (CVT = 10 +/- 1 ml/kg) and low VT (LVT = 6 +/- 1 ml/ kg); total PEEP (PEEPtot) was individually set at the lower inflection point (Plip) of the pressure-volume curve (PEEPtot = 11 +/- 4 cm H(2)O). Pressure-volume curves were recorded from zero PEEP (ZEEP) and from PEEP, and recruited volume (Vrec) was calculated as the volume difference between the two curves for a given pressure. Despite a similar PEEPtot, Vrec was significantly lower with LVT than with CVT, indicating low VT-induced alveolar derecruitment. Reduction in VT was associated with a reduced Sa(O(2)). In 10 patients, Vrec was also measured before and after a recruitment maneuver (two sustained inflations at 45 cm H(2)O), and after an increase in PEEP (by 4 cm H(2)O). Low VT-induced derecruitment was reversed by a recruitment maneuver and by increasing PEEP. We conclude that a reduction in VT could be responsible for alveolar derecruitment, which may be transiently reversed by a reexpansion maneuver or prevented by a PEEP increase above Plip.
Measuring elastic pressure-volume (Pel-V) curves of the respiratory system and the volume recruited by a positive end-expiratory pressure (PEEP) allows one to study the pressure range over which ...recruitment occurs in acute lung injury (ALI), and to explain how recruitment affects the compliance. Pel-V curves were measured with the low flow inflation technique in 11 patients mechanically ventilated for ALI. Curve I was recorded during inflation from the volume attained after a prolonged expiration (6 s) at PEEP (9.0 +/- 2.2 cm H2O), and Curve II after expiration to the elastic equilibrium volume at zero end-expiratory pressure (ZEEP). By using the end-expiratory volume of the breaths, the curves were aligned on a common volume axis to determine the effect of a single complete expiration. In each patient, Curve II (from ZEEP) was shifted toward lower volumes than Curve I. The volume shift, probably due to derecruitment, was 205 +/- 100 ml at 15 cm H2O (p < 0.01) and 78 +/- 93 ml at 30 cm H2O (p < 0.01); thus, during inflation from ZEEP, the volume deficit was successively regained over a pressure range up to at least 30 cm H2O. At any pressure, compliance was higher on the curve from ZEEP than from PEEP, by 10.0 +/- 8.7 ml/cm H2O at 15 cm H2O (p < 0.01), and by 5.4 +/- 5.5 at 30 cm H2O (p < 0.01). It is concluded that in ALI, a single expiration to ZEEP leads to lung collapse. High compliance during insufflation from ZEEP indicates that lung recruitment happens far above the lower inflection point of the Pel-V curve.
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