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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>
Sö,derhä,ll, Irene,Wu, Chenglin,Novotny, Marian,Lee, Bok Luel,Sö,derhä,ll, Kenneth American Society for Biochemistry and Molecular Bi 2009 The Journal of biological chemistry Vol.284 No.10
<P>Melanization is an important immune component of the innate immune system of invertebrates and is vital for defense as well as for wound healing. In most invertebrates melanin synthesis is achieved by the prophenoloxidase-activating system, a proteolytic cascade similar to vertebrate complement. Even though melanin formation is necessary for host defense in crustaceans and insects, the process needs to be tightly regulated because of the hazard to the animal of unwanted production of quinone intermediates and melanization in places where it is not suitable. In the present study we have identified a new melanization inhibition protein (MIP) from the hemolymph of the crayfish, Pacifastacus leniusculus. Crayfish MIP has a similar function as the insect MIP molecule we recently discovered in the beetle Tenebrio molitor but interestingly has a completely different sequence. Crayfish MIP as well as Tenebrio MIP do not affect phenoloxidase activity in itself but instead interfere with the melanization reaction from quinone compounds to melanin. Importantly, crayfish MIP in contrast to Tenebrio MIP contains a fibrinogen-like domain, most similar to the substrate recognition domain of vertebrate l-ficolins. Surprisingly, an Asp-rich region similar to that found in ficolins that is likely to be involved in Ca2+ binding is present in crayfish MIP. However, crayfish MIP did not show any hemagglutinating activity as is common for the vertebrate ficolins. A mutant form of MIP with a deletion lacking four Asp amino acids from the Asp-rich region lost most of its activity, implicating that this part of the protein is involved in regulating the prophenoloxidase activating cascade. Overall, a new negative regulator of melanization was identified in freshwater crayfish that shows interesting parallels with proteins (i.e. ficolins) involved in vertebrate immune response.</P>
Jä,ger, K.,Bartó,k, T.,Ö,rdö,g, V.,Barnabá,s, B. Elsevier 2010 South African journal of botany : official journal Vol.76 No.3
<P><B>Abstract</B></P><P>This is the first report on the beneficial effect of microalgal and cyanobacterial biomass on anther cultures of maize (<I>Zea mays</I> L.). Investigations were made on the cytokinin- and auxin-like activity and content of terrestrial and fresh-water living microalgal and cyanobacterial strains. The influence of media supplemented with biomass from four selected strains on the anther induction, the frequency of microspore-derived embryo-like structures, and regeneration capacity in anther cultures of maize was also studied. The addition of cyanobacterial and microalgal biomass to the induction and regeneration media in concentrations of 1 or 2g/L improved the androgenic response, and was able to reduce the quantity of the synthetic auxin 2,4-dichlorophenoxy-acetic acid (2,4-D) required, or replace it completely.</P>
Microscopic control ofSi29nuclear spins near phosphorus donors in silicon
Jä,rvinen, J.,Zvezdov, D.,Ahokas, J.,Sheludyakov, S.,Vainio, O.,Lehtonen, L.,Vasiliev, S.,Fujii, Y.,Mitsudo, S.,Mizusaki, T.,Gwak, M.,Lee, SangGap,Lee, Soonchil,Vlasenko, L. American Physical Society 2015 Physical review. B, Condensed matter and materials Vol.92 No.12
White, J S,Forgan, E M,Laver, M,Hä,fliger, P S,Khasanov, R,Cubitt, R,Dewhurst, C D,Park, M-S,Jang, D-J,Lee, H-G,Lee, S-I IOP Pub 2008 Journal of physics, an Institute of Physics journa Vol.20 No.10
<P>We report on the first small-angle neutron scattering measurements from the flux line lattice (FLL) in the high-<I>T</I><SUB>c</SUB> cuprate superconductor Sr<SUB>0.9</SUB>La<SUB>0.1</SUB>CuO<SUB>2</SUB>. Using a polycrystalline sample, the scattered intensity decreases monotonically with scattering angle away from the undiffracted beam, independently of the azimuthal angle around the beam. The absence of clear peaks in the intensity suggests the establishment of a highly disordered FLL within the grains. We find that the intensity distribution may be represented by the form factor for a single flux line in the London approximation, with some contribution from crystal anisotropy. Most interestingly however, we find that, over the observed field range, the temperature dependence of the diffracted intensity is best represented by s-wave pairing, with lower limits of the gap values being very similar to the Bardeen–Cooper–Schrieffer value of Δ(0) = 1.76<I> k</I><SUB>B</SUB><I>T</I><SUB>c</SUB>. However, a qualitative consideration of corrections to the observed intensity suggests that these gap values are likely to be higher, implying strong-coupling behaviour.</P>
Fuchs, Hendrik,Tan, Zhaofeng,Lu, Keding,Bohn, Birger,Broch, Sebastian,Brown, Steven S.,Dong, Huabin,Gomm, Sebastian,Hä,seler, Rolf,He, Lingyan,Hofzumahaus, Andreas,Holland, Frank,Li, Xin,Liu, Ying Copernicus GmbH 2017 Atmospheric chemistry and physics Vol.17 No.1
<P>Abstract. In 2014, a large, comprehensive field campaign was conducted in the densely populated North China Plain. The measurement site was located in a botanic garden close to the small town Wangdu, without major industry but influenced by regional transportation of air pollution. The loss rate coefficient of atmospheric hydroxyl radicals (OH) was quantified by direct measurements of the OH reactivity. Values ranged between 10 and 20 s−1 for most of the daytime. Highest values were reached in the late night with maximum values of around 40 s−1. OH reactants mainly originated from anthropogenic activities as indicated (1) by a good correlation between measured OH reactivity and carbon monoxide (linear correlation coefficient R2 = 0.33) and (2) by a high contribution of nitrogen oxide species to the OH reactivity (up to 30 % in the morning). Total OH reactivity was measured by a laser flash photolysis-laser-induced fluorescence instrument (LP-LIF). Measured values can be explained well by measured trace gas concentrations including organic compounds, oxygenated organic compounds, CO and nitrogen oxides. Significant, unexplained OH reactivity was only observed during nights, when biomass burning of agricultural waste occurred on surrounding fields. OH reactivity measurements also allow investigating the chemical OH budget. During this campaign, the OH destruction rate calculated from measured OH reactivity and measured OH concentration was balanced by the sum of OH production from ozone and nitrous acid photolysis and OH regeneration from hydroperoxy radicals within the uncertainty of measurements. However, a tendency for higher OH destruction compared to OH production at lower concentrations of nitric oxide is also observed, consistent with previous findings in field campaigns in China. </P>
<i>SUZAKU</i>/WAM AND<i>RHESSI</i>OBSERVATIONS OF NON-THERMAL ELECTRONS IN SOLAR MICROFLARES
Ishikawa, Shin-nosuke,Krucker, Sä,m,Ohno, Masanori,Lin, Robert P. IOP Publishing 2013 The Astrophysical journal Vol.765 No.2
<P>We report on hard X-ray spectroscopy of solar microflares observed by the Wide-band All-sky Monitor (WAM), on board the Suzaku satellite, and by RHESSI. WAM transient data provide wide energy band (50 keV-5 MeV) spectra over a large field of view (similar to 2 pi sr) with a time resolution of 1 s. WAM is attractive as a hard X-ray solar flare monitor due to its large effective area (similar to 800 cm(2) at 100 keV, similar to 13 times larger than that of RHESSI). In particular, this makes it possible to search for high energy emission in microflares that is well below the RHESSI background. The WAM solar flare list contains six GOES B-class microflares that were simultaneously observed by RHESSI between the launch of Suzaku in 2005 July and 2010 March. At 100 keV, the detected WAM fluxes are more than similar to 20 times below the typical RHESSI instrumental background count rates. The RHESSI and WAM non-thermal spectra are in good agreement with a single power law with photon spectral indices between 3.3 and 4.5. In a second step, we also searched the RHESSI microflare list for events that should be detectable by WAM, assuming that the non-thermal power-law emission seen by RHESSI extends to >50 keV. From the 12 detectable events between 2005 July and 2007 February, 11 were indeed seen by WAM. This shows that microflares, similar to regular flares, can accelerate electrons to energies up to at least 100 keV.</P>
Chatrchyan, S.,Khachatryan, V.,Sirunyan, A. M.,Tumasyan, A.,Adam, W.,Bergauer, T.,Dragicevic, M.,Erö,, J.,Fabjan, C.,Friedl, M.,Frü,hwirth, R.,Ghete, V. M.,Hammer, J.,Hä,nsel, S.,Hoch, M. Springer-Verlag 2011 Journal of high energy physics Vol.2011 No.6
<P>A search is performed for an excess of events, over the standard model expectations, with a photon, a lepton, and large missing transverse energy in pp collisions root s = 7TeV. Such events are expected in many new physics models, in particular a theory that is broken via a gauge-mediated mechanism, when the lightest and neutral gauginos are mass degenerate. The data sample used in this search to an integrated luminosity of 35 pb(-1) collected with the CMS detector at the No evidence of such an excess above the standard model backgrounds, dominated by production, is found. The results are presented as 95% confidence level upper limits on the cross section for a benchmark gauge-mediated scenario, and are then converted into exclusion limits on the squark, gluino, and wino masses.</P>
ON THE RELATION OF ABOVE-THE-LOOP AND FOOTPOINT HARD X-RAY SOURCES IN SOLAR FLARES
Ishikawa, S.,Krucker, Sä,m,Takahashi, T.,Lin, R. P. IOP Publishing 2011 The Astrophysical journal Vol.737 No.2
<P>We report on the most prominent example of an above-the-loop hard X-ray source in the extensive solar flare database of RHESSI. The limb flare of 2003 October 22 around 20 UT resembles the famous Masuda flare, except that only one of the footpoint sources is visible with the other one occulted. However, even for this very prominent event, the above-the-loop source is only visible during one of the four hard X-ray peaks, highlighting the rare occurrence of above-the-loop sources that are equally bright as footpoint sources. The relative timing between the above-the-loop and footpoint sources shows that the coronal source peaks about 10 s before the footpoint source and decays during the time the footpoint source is most prominent. Furthermore, the derived number of non-thermal electrons within the above-the-loop source is large enough to provide the needed number of precipitating electrons to account for the footpoint emission over the duration of the hard X-ray peak. Hence, these observations support the simple scenario where bulk energization is accelerating all electrons within the above-the-loop source and precipitating electrons are emptying out of the above-the-loop source to produce the footpoint emissions.</P>