179 research outputs found
Excitation and deexcitation processes in atom-Rydberg atom collisions in helium-rich white dwarf atmospheres
We aim to show the importance of non-elastic excitation and deexcitation
processes in collisions with the
principal quantum number for helium-rich white dwarf atmospheres. We
compare the efficiencies of these processes with those of the known non-elastic
electron- atom processes in the atmospheres of some DB
white dwarfs. We show that in significant parts of the considered atmospheres,
which contain weakly ionized layers (the ionization degree ),
the influence of the studied atom-Rydberg atom processes on excited helium atom
populations is dominant or at least comparable to the influence of the
concurrent electron--atom processes.Comment: Astronomy & Astrophysics, Accepted: 14 February 201
The influence of the radiative non-symmetric ion-atom collisions on the stellar atmospheres in VUV region
The aim of this work is to draw attention to the processes of radiative
charge exchange in non-symmetric ion-atom collisions as a factor of influence
on the opacity of stellar atmospheres in VUV region. For that purpose
calculations of the spectral absorption coefficients for several ion-atom
systems, namely: He + H and H + X, where X = Na and Li have been
performed. On chosen examples it has been established that the examined
processes generate rather wide molecular absorption bands in the VUV region,
which should be taken into account for the interpretation of data obtained from
laboratory measurements or astrophysical observations. In this paper the
potential significance is discussed of the considered radiative processes for
DB white dwarfs and solar atmospheres, as well as for the atmospheres of the
so-called lithium stars
Ion-atom radiative processes in the solar atmosphere: quiet Sun and sunspots
In the previous works the significance of the symmetric and non-symmetric
ion-atom absorption processes in far UV and EUV regions within a model of the
quiet Sun atmosphere, has been studied. The considered processes were the
processes of the photo-dissociation of the molecular ions H and
H and absorption processes in H+H and H collisions, where
denotes the metal atom. As the continuation of the previous investigation,
these processes are considered also within the corresponding sunspot model. In
this work the non-symmetric ion-atom absorption processes are considered with
Mg, Si, etc. It was analyzed the significance of such processes in far UV
and EUV regions in comparison with the concurrent absorption processes,
especially with the processes of the photo-ionization of the metal atoms (Na,
Mg, Ca, etc.) which were not included in the consideration in the case of the
quiet Sun atmosphere. From our analysis it follows that the non-symmetric
ion-atom absorption processes considered here, are significant not only for
quiet Sun modeling but also for sunspots and should be included {\it ab initio}
in both cases.Comment: accepted in Advances in Space Researc
Fractional flow reserve in patients with intermediate values of Duke Treadmill Score and borderline coronary lesions
Despite the wide usage of exercise ECG tests and Duke Treadmill Score (DTS) in clinical practice, no comparison between this scoring system and Fractional Flow Reserve (FFR) has yet been made, particularly in cases of angiographically verified borderline lesions. Thirty patients with single coronary lesions and angiographically assessed borderline stenosis (between 30-70%) and previously calculated intermediate values of DTS between -10 to +4 were examined using FFR. Adequate specificity and sensitivity (0.769 and 0.556, respectively) were in a more narrow range of -0.5 to -10. Sex and age did not have an influence on the DTS values. There was a correlation between the values of FFR and age (r=0.395, p=0.031) and between angiographic assessment of stenosis and quantitative coronary angiography (QCA) (r=0.648, p<0.0001). In the study population, a decision on revascularization could not be based solely on angiographic or QCA assessment of the artery or on the values of DTS
Bowel function and quality of life after superior mesenteric nerve plexus transection in right colectomy with D3 extended mesenterectomy
Background: The aim of this study was to ascertain the impact of injury to the superior mesenteric nerve plexus caused by right colectomy with D3 extended mesenterectomy as performed in the prospective multicenter trial: “Safe Radical D3 Right Hemicolectomy for Cancer through Preoperative Biphasic Multi-detector Computed Tomography” in which all soft tissue surrounding the superior mesenteric vessels from the level of the middle colic artery to that of the ileocolic artery was removed. Methods: Bowel function and gastrointestinal quality of life in two consecutive cohorts that underwent right colectomy with and without D3 extended mesenterectomy were compared. Main outcome measures were the Diarrhea Assessment Scale (DAS) and Gastrointestinal Quality of Life Index (GIQLI). The data were collected prospectively through telephone interviews. Results: Forty-nine patients per group, comparable for age, sex, length of bowel resected but with significantly shorter follow-up time in the experimental group, were included. There was no difference in total DAS scores, subscores or additional questions except for higher bowel frequency scores in the D3 group (p = 0.02). Comparison of total GIQLI scores and subscales showed no difference between groups. Regression analysis with correction for confounding factors showed 0.48 lower bowel frequency scores in the D2 group (p = 0.022). Within the D3 group presence of jejunal arteries cranial to the D3 dissection area showed 1.78 lower DAS scores and 0.7 lower bowel frequency scores. Conclusions: Small bowel denervation after right colectomy with D3 extended mesenterectomy leads to increased bowel frequency but does not impact gastrointestinal quality of life. Individual anatomical variants can affect postoperative bowel function differently despite standardized surgery.acceptedVersio
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