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The H <small>i</small> environment of counter‐rotating gas hosts: gas accretion from cold gas blobs
Chung, Aeree,Bureau, Martin,van Gorkom, J. H.,Koribalski, Bä,rbel Blackwell Publishing Ltd 2012 Monthly notices of the Royal Astronomical Society Vol.422 No.2
<P><B>ABSTRACT</B></P><P>We probe the H <SMALL>i</SMALL> properties and the gas environments of three early‐type barred galaxies harbouring counter‐rotating ionized gas: NGC 128, NGC 3203 and NGC 7332. Each system has one or more optically identified galaxy at a similar or as yet unknown redshift within a 50‐kpc projected radius. Using H <SMALL>i</SMALL> synthesis imaging data, we investigate the hypothesis that the counter‐rotating gas in these galaxies has been accreted from their neighbours. In NGC 128 and NGC 3203, we find 9.6 × 10<SUP>7</SUP> and 2.3 × 10<SUP>8</SUP> M<SUB>⊙</SUB> of H <SMALL>i</SMALL>, respectively, covering almost the entire stellar bodies of dwarf companions that appear physically connected. Both the H <SMALL>i</SMALL> morphology and kinematics are suggestive of tidal interactions. In NGC 7332, we do not find any directly associated H <SMALL>i</SMALL>. Instead, NGC 7339, a neighbour of a comparable size at about 10 kpc, is found with 8.9 × 10<SUP>8</SUP> M<SUB>⊙</SUB> of H <SMALL>i</SMALL> gas. More recently in a single dish observation, however, another group discovered a large H <SMALL>i</SMALL> structure which seems to be an extension of NGC 7339’s H <SMALL>i</SMALL> disc and also covers NGC 7332. All these observations thus suggest that H <SMALL>i</SMALL> gas is being accreted in these three galaxies from their companions, which is likely responsible for the kinematically decoupled gas component present in their central region. In particular, the dynamical friction time‐scales of the nearest neighbours with H <SMALL>i</SMALL> gas of NGC 128 and NGC 3203 are comparable to their orbital time‐scales around the counter‐rotators, several ∼10<SUP>8</SUP> yr, implying that those neighbours will likely soon merge with the primary galaxies, fuelling them with gas. NGC 7332 also appears to be in the merging process with its neighbour through the common H <SMALL>i</SMALL> envelope. Besides, we find some other potential gas donors around NGC 128 and NGC 7332: two H <SMALL>i</SMALL>‐rich galaxies with <IMG src='/wiley-blackwell_img/equation/MNR_20679_mu1.gif' alt ='inline image'/> and 2.5 × 10<SUP>9</SUP> M<SUB>⊙</SUB> at a distance of ≈67 kpc from NGC 128 and two dwarf systems with <I>M</I><SUB>HI</SUB>= 3.9 × 10<SUP>7</SUP> and 7.4 × 10<SUP>7</SUP> M<SUB>⊙</SUB> at ≲100 kpc from NGC 7332. Among the seven H <SMALL>i</SMALL> features identified in this study, three of them are associated with dwarf galaxies, two of which have only been recently identified in a blind survey, while the third one is still not catalogued at optical wavelengths. Considering the incompleteness of existing studies of the faint dwarf galaxy population both in the optical and in H <SMALL>i</SMALL>, accretion from cold gas blobs, presumably gas‐rich dwarfs, is expected to occur even more frequently than what is inferred from such cases that have been observed to date.</P>
Calderón–Zygmund estimates in generalized Orlicz spaces
Hä,stö,, Peter,Ok, Jihoon Academic Press 2019 Journal of differential equations Vol.267 No.5
<P><B>Abstract</B></P> <P>We establish the <SUP> W 2 , φ ( ⋅ ) </SUP> -solvability of the linear elliptic equations in non-divergence form under a suitable, essentially minimal, condition of the generalized Orlicz function φ ( ⋅ ) = φ ( x , t ) , by deriving Calderón–Zygmund type estimates. The class of generalized Orlicz spaces we consider here contains as special cases classical Lebesgue and Orlicz spaces, as well as non-standard growth cases like variable exponent and double phase growth.</P>
MEASUREMENTS OF THE CORONAL ACCELERATION REGION OF A SOLAR FLARE
Krucker, Sä,m,Hudson, H. S.,Glesener, L.,White, S. M.,Masuda, S.,Wuelser, J.-P.,Lin, R. P. IOP Publishing 2010 The Astrophysical journal Vol.714 No.2
<P>The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and the Nobeyama Radioheliograph (NoRH) are used to investigate coronal hard X-ray and microwave emissions in the partially disk-occulted solar flare of 2007 December 31. The STEREO mission provides EUV images of the flare site at different viewing angles, establishing a two-ribbon flare geometry and occultation heights of the RHESSI and NoRH observations of similar to 16 Mm and similar to 25 Mm, respectively. Despite the occultation, intense hard X-ray emission up to similar to 80 keV occurs during the impulsive phase from a coronal source that is also seen in microwaves. The hard X-ray and microwave source during the impulsive phase is located similar to 6 Mm above thermal flare loops seen later at the soft X-ray peak time, similar in location to the above-the-loop-top source in the Masuda flare. A single non-thermal electron population with a power-law distribution (with spectral index of similar to 3.7 from similar to 16 keV up to the MeV range) radiating in both bremsstrahlung and gyrosynchrotron emission can explain the observed hard X-ray and microwave spectrum, respectively. This clearly establishes the non-thermal nature of the above-the-loop-top source. The large hard X-ray intensity requires a very large number (>5 x 10(35) above 16 keV for the derived upper limit of the ambient density of similar to 8 x 10(9) cm(-3)) of suprathermal electrons to be present in this above-the-loop-top source. This is of the same order of magnitude as the number of ambient thermal electrons. We show that collisional losses of these accelerated electrons would heat all ambient electrons to superhot temperatures (tens of keV) within seconds. Hence, the standard scenario, with hard X-rays produced by a beam comprising the tail of a dominant thermal core plasma, does not work. Instead, all electrons in the above-the-loop-top source seem to be accelerated, suggesting that the above-the-loop-top source is itself the electron acceleration region.</P>
Revealing community structures by ensemble clustering using group diffusion
Ivannikova, Elena,Park, Hyunwoo,Hä,mä,lä,inen, Timo,Lee, Kichun Elsevier 2018 Information fusion Vol.42 No.-
<P><B>Abstract</B></P> <P>We propose an ensemble clustering approach using group diffusion to reveal community structures in data. We represent data points as a directed graph and assume each data point belong to single cluster membership instead of multiple memberships. The method is based on the concept of ensemble group diffusion with a parameter to represent diffusion depth in clustering. The ability to modulate the diffusion-depth parameter by varying it within a certain interval allows for more accurate construction of clusters. Depending on the value of the diffusion-depth parameter, the presented approach can determine very well both local clusters and global structure of data. At the same time, the ability to combine single outcomes of the method results in better cluster segmentation. Due to this property, the proposed method performs well on data sets where other conventional clustering methods fail. We test the method with both simulated and real-world data sets. The results support our theoretical conjectures on improved accuracy compared to other selected methods.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Robust clustering results by integrating views from individual diffusion scales. </LI> <LI> Regulating cluster sizes by an admitted group dependence level. </LI> <LI> Handling directed graphs. </LI> <LI> Flexibility in the tuning of the parameters. </LI> <LI> Adaptation to datasets with various underlying structure and density properties. </LI> </UL> </P>
Thermal ageing and short-range ordering of Alloy 690 between 350 and 550 °C
Mouginot, Roman,Sarikka, Teemu,Heikkilä,, Mikko,Ivanchenko, Mykola,Ehrnsté,n, Ulla,Kim, Young Suk,Kim, Sung Soo,Hä,nninen, Hannu Elsevier 2017 Journal of nuclear materials Vol.485 No.-
<P><B>Abstract</B></P> <P>Thermal ageing of Alloy 690 triggers an intergranular (IG) carbide precipitation and is known to promote an ordering reaction causing lattice contraction. It may affect the long-term primary water stress corrosion cracking (PWSCC) resistance of pressurized water reactor (PWR) components. Four conditions of Alloy 690 (solution annealed, cold-rolled and/or heat-treated) were aged between 350 and 550 °C for 10 000 h and characterized. Although no direct observation of ordering was made, variations in hardness and lattice parameter were attributed to the formation of short-range ordering (SRO) in all conditions with a peak level at 420 °C, consistent with the literature. Prior heat treatment induced ordering before thermal ageing. At higher temperatures, stress relaxation, recrystallization and α-Cr precipitation were observed in the cold-worked samples, while a disordering reaction was inferred in all samples based on a decrease in hardness. IG precipitation of M<SUB>23</SUB>C<SUB>6</SUB> carbides increased with increasing ageing temperature in all conditions, as well as diffusion-induced grain boundary migration (DIGM).</P> <P><B>Highlights</B></P> <P> <UL> <LI> SRO was suggested in Alloy 690 with 9.18 wt% Fe after thermal ageing at 350, 420 and 475 °C. </LI> <LI> Prior thermal treatment promoted SRO before ageing. </LI> <LI> Cold work led to recrystallization and precipitation of α-Cr upon ageing at 550 °C. </LI> <LI> Thermal ageing promoted IG precipitation of Cr-rich M<SUB>23</SUB>C<SUB>6</SUB> carbides and DIGM. </LI> </UL> </P>
Proton Shell Evolution below Sn132 : First Measurement of Low-Lying β -Emitting Isomers in Ag123,125
Chen, Z. Q.,Li, Z. H.,Hua, H.,Watanabe, H.,Yuan, C. X.,Zhang, S. Q.,Lorusso, G.,Nishimura, S.,Baba, H.,Browne, F.,Benzoni, G.,Chae, K. Y.,Crespi, F. C. L.,Doornenbal, P.,Fukuda, N.,Gey, G.,Gernhä American Physical Society 2019 Physical Review Letters Vol.122 No.21
Induced versus intrinsic magnetic moments in ultrafast magnetization dynamics
Hofherr, M.,Moretti, S.,Shim, J.,Hä,user, S.,Safonova, N. Y.,Stiehl, M.,Ali, A.,Sakshath, S.,Kim, J. W.,Kim, D. H.,Kim, H. J.,Hong, J. I.,Kapteyn, H. C.,Murnane, M. M.,Cinchetti, M.,Steil, D.,Math American Physical Society 2018 Physical Review B Vol.98 No.17