MEASUREMENTS OF THE CORONAL ACCELERATION REGION OF A SOLAR FLARE

Krucker, S&auml,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>

Optical and UV surface brightness of translucent dark nebulae : Dust albedo, radiation field, and fluorescence emission by H₂

Mattila, K.,Haas, M.,Haikala, L. K.,Jo, Y-S.,Lehtinen, K.,Leinert, Ch.,V&auml,is&auml,nen, P. Springer-Verlag 2018 Astronomy and astrophysics Vol.617 No.-

<P><I>Context.</I> Dark nebulae display a surface brightness because dust grains scatter light of the general interstellar radiation field (ISRF). High-galactic-latitudes dark nebulae are seen as bright nebulae when surrounded by transparent areas which have less scattered light from the general galactic dust layer.</P><P><I>Aims.</I> Photometry of the bright dark nebulae LDN 1780, LDN 1642, and LBN 406 shall be used to derive scattering properties of dust and to investigate the presence of UV fluorescence emission by molecular hydrogen and the extended red emission (ERE).</P><P><I>Methods.</I> We used multi-wavelength optical photometry and imaging at ground-based telescopes and archival imaging and spectroscopic UV data from the spaceborn GALEX and SPEAR/FIMS instruments. In the analysis we used Monte Carlo RT and both observational data and synthetic models for the ISRF in the solar neighbourhood. The line-of-sight extinctions through the clouds have been determined using near infrared excesses of background stars and the 200/250 <I>μ</I>m far infrared emission by dust as measured using the ISO and <I>Herschel</I> space observatories.</P><P><I>Results.</I> The optical surface brightness of the three target clouds can be explained in terms of scattered light. The dust albedo ranges from ~0.58 at 3500 Å to ~0.72 at 7500 Å. The spectral energy distribution of LDN 1780 is explained in terms of optical depth and background scattered light effects instead of the original published suggestion in terms of ERE. The far-ultraviolet surface brightness of LDN 1780 cannot be explained by scattered light only. In LDN 1780, H2 fluorescent emission in the wavelength range 1400-1700 Å has been detected and analysed.</P><P><I>Conclusions.</I> Our albedo values are in good agreement with the predictions of the dust model of Weingartner and Draine and with the THEMIS CMM model for evolved core-mantle grains. The distribution of H2 fluorescent emission in LDN 1780 shows a pronounced dichotomy with a strong preference for its southern side where enhanced illumination is impinging from the Sco OB2 association and the O star <I>ζ</I> Oph. A good correlation is found between the H2 fluorescence and a previously mapped 21-cm excess emission. The H2 fluorescence emission in LDN 1780 has been modelled using a PDR code; the resulting values for H2 column density and the total gas density are consistent with the estimates derived from CO observations and optical extinction along the line of sight.</P>

Peroxiredoxins, a novel protein family in lung cancer

Lehtonen, Siri T.,Svensk, Anne-Mari,Soini, Ylermi,Pä,&auml,kkö,, Paavo,Hirvikoski, Pasi,Kang, Sang Won,S&auml,ily, Marjaana,Kinnula, Vuokko L. Wiley Subscription Services, Inc., A Wiley Company 2004 International journal of cancer: Journal internati Vol.111 No.4

<P>Cigarette smoke, the major risk factor for lung cancer, induces an accumulation of reactive oxygen species. These have multiple effects on cell defense, cell proliferation and cell death. Thus, compounds involved in the regulators of redox balance can be hypothesized to play a fundamental role in both carcinogenesis and tumor progression. Here, we have evaluated the expressions of all 6 peroxiredoxins (Prxs I–VI) in lung carcinomas. Prxs represent a protein family with the capability of breaking down hydrogen peroxide; thus, they can participate in cellular antioxidant defense, regulate cell proliferation and increase drug resistance of cultured cells. Altogether 92 cases were investigated by immunohistochemistry, including 32 adenocarcinomas, 45 squamous cell, 9 small cell and 6 other carcinomas. Additionally, 11 cases with adenocarcinoma or squamous cell carcinoma were studied by Western analysis and/or by RT-PCR. Prxs I, II, IV and VI were particularly elevated in lung carcinomas as assessed by immunohistochemistry and/or RT-PCR. Western analysis revealed that Prxs I and IV were significantly elevated in tumors compared to nonmalignant tissue (p = 0.04 and 0.002, respectively). There were remarkable variations in Prx expression in various tumor subtypes, the most striking being Prx IV expression, which was mainly associated with adenocarcinoma. Elevated Prx VI expression was associated with high-grade squamous cell carcinoma (p = 0.03) and Prx II expression, with advanced tumor stage (p = 0.01). Our results suggest that Prxs may have effects on the progression of lung cancer. © 2004 Wiley-Liss, Inc.</P>

Practical sample pretreatment techniques coupled with capillary electrophoresis for real samples in complex matrices

Jarvas, Gabor,Guttman, Andras,Mię,kus, Natalia,Bą,czek, Tomasz,Jeong, Sunkyung,Chung, Doo Soo,Pä,toprstý,, Vladimir,Masá,r, Mariá,n,Hutta, Milan,Datinská,, Vladim Elsevier 2020 Trends in analytical chemistry Vol.122 No.-

<P><B>Abstract</B></P> <P>By coupling a sample pretreatment technique of sample clean up and enrichment power with capillary electrophoresis (CE) of high-performance separation, the task of analyzing trace analytes in a complex matrix such as a biological sample can be carried out successfully with ease. This review aims for providing an overview of strategies to couple sample pretreatment techniques with capillary and related microscale (e.g., microchip) electrophoresis, practically adoptable in an automatic manner, without requiring serious modification of existing instruments to install sophisticated interfaces. In-line sample pretreatment techniques based on liquid phase microextraction performed before sample injection and on-line sample preconcentration techniques performed during or after sample injection are discussed with emphasis on the applicability to samples of high conductivity, commonly encountered for biological samples. An overview of the recent developments in microfluidic immobilized enzymatic microreactors which fit excellently to microchip CE is also given.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Recent advances and major trends in sample pretreatment for capillary electrophoresis are summarized. </LI> <LI> In-line and on-line sample pretreatment techniques are discussed with emphasis on biological samples. </LI> <LI> We provide an overview of strategies to couple sample pretreatment techniques with capillary and microchip electrophoresis. </LI> </UL> </P>

The 8th International Comparison of Absolute Gravimeters 2009: the first Key Comparison (CCM.G-K1) in the field of absolute gravimetry

Jiang, Z,Pá,linká,š,, V,Arias, F E,Liard, J,Merlet, S,Wilmes, H,Vitushkin, L,Robertsson, L,Tisserand, L,Pereira Dos Santos, F,Bodart, Q,Falk, R,Baumann, H,Mizushima, S,M&auml,kinen, J Springer-Verlag 2012 METROLOGIA -BERLIN- Vol.49 No.6

<P>The 8th International Comparison of Absolute Gravimeters (ICAG2009) took place at the headquarters of the International Bureau of Weights and Measures (BIPM) from September to October 2009. It was the first ICAG organized as a key comparison in the framework of the CIPM Mutual Recognition Arrangement of the International Committee for Weights and Measures (CIPM MRA) (CIPM 1999). ICAG2009 was composed of a Key Comparison (KC) as defined by the CIPM MRA, organized by the Consultative Committee for Mass and Related Quantities (CCM) and designated as CCM.G-K1. Participating gravimeters and their operators came from national metrology institutes (NMIs) or their designated institutes (DIs) as defined by the CIPM MRA. A Pilot Study (PS) was run in parallel in order to include gravimeters and their operators from other institutes which, while not signatories of the CIPM MRA, nevertheless play important roles in international gravimetry measurements. The aim of the CIPM MRA is to have international acceptance of the measurement capabilities of the participating institutes in various fields of metrology. The results of CCM.G-K1 thus constitute an accurate and consistent gravity reference traceable to the SI (International System of Units), which can be used as the global basis for geodetic, geophysical and metrological observations of gravity. The measurements performed afterwards by the KC participants can be referred to the international metrological reference, i.e. they are SI-traceable.</P><P>The ICAG2009 was complemented by a number of associated measurements: the Relative Gravity Campaign (RGC2009), high-precision levelling and an accurate gravity survey in support of the BIPM watt balance project. The major measurements took place at the BIPM between July and October 2009. Altogether 24 institutes with 22 absolute gravimeters (one of the 22 AGs was ultimately withdrawn) and nine relative gravimeters participated in the ICAG/RGC campaign.</P><P>This paper is focused on the absolute gravity campaign. We review the history of the ICAGs and present the organization, data processing and the final results of the ICAG2009.</P><P>After almost thirty years of hosting eight successive ICAGs, the CIPM decided to transfer the responsibility for piloting the future ICAGs to NMIs, although maintaining a supervisory role through its Consultative Committee for Mass and Related Quantities.</P>

SQUIDs in biomagnetism: a roadmap towards improved healthcare

Kö,rber, Rainer,Storm, Jan-Hendrik,Seton, Hugh,M&auml,kel&auml,, Jyrki P,Paetau, Ritva,Parkkonen, Lauri,Pfeiffer, Christoph,Riaz, Bushra,Schneiderman, Justin F,Dong, Hui,Hwang, Seong-min,You, Lixi IOP 2016 Superconductor science & technology Vol.29 No.11

<P>Globally, the demand for improved health care delivery while managing escalating costs is a major challenge. Measuring the biomagnetic fields that emanate from the human brain already impacts the treatment of epilepsy, brain tumours and other brain disorders. This roadmap explores how superconducting technologies are poised to impact health care. Biomagnetism is the study of magnetic fields of biological origin. Biomagnetic fields are typically very weak, often in the femtotesla range, making their measurement challenging. The earliest <I>in vivo</I> human measurements were made with room-temperature coils. In 1963, Baule and McFee (1963 <I>Am</I>. <I>Heart J</I>. <A HREF='http://dx.doi.org/10.1016/0002-8703(63)90075-9'> <B>55</B> 95−6</A>) reported the magnetic field produced by electric currents in the heart (‘magnetocardiography’), and in 1968, Cohen (1968 <I>Science</I> <A HREF='http://dx.doi.org/10.1126/science.161.3843.784'> <B>161</B> 784−6</A>) described the magnetic field generated by alpha-rhythm currents in the brain (‘magnetoencephalography’). Subsequently, in 1970, Cohen <I>et al</I> (1970 <I>Appl. Phys. Lett.</I> <A HREF='http://dx.doi.org/10.1063/1.1653195'> <B>16</B> 278–80</A>) reported the recording of a magnetocardiogram using a Superconducting QUantum Interference Device (SQUID). Just two years later, in 1972, Cohen (1972 <I>Science</I> <A HREF='http://dx.doi.org/10.1126/science.175.4022.664'> <B>175</B> 664–6</A>) described the use of a SQUID in magnetoencephalography. These last two papers set the scene for applications of SQUIDs in biomagnetism, the subject of this roadmap.</P> <P>The SQUID is a combination of two fundamental properties of superconductors. The first is flux quantization—the fact that the magnetic flux Φ in a closed superconducting loop is quantized in units of the magnetic flux quantum, Φ<SUB>0</SUB> ≡ <I>h</I>/2<I>e</I>, ≈ 2.07 × 10<SUP>−15</SUP> Tm<SUP>2</SUP> (Deaver and Fairbank 1961 <I>Phys. Rev. Lett.</I> <A HREF='http://dx.doi.org/10.1103/PhysRevLett.7.43'> <B>7</B> 43–6</A>, Doll R and Näbauer M 1961 <I>Phys. Rev. Lett.</I> <A HREF='http://dx.doi.org/10.1103/PhysRevLett.7.51'> <B>7</B> 51–2</A>). Here, <I>h</I> is the Planck constant and <I>e</I> the elementary charge. The second property is the Josephson effect, predicted in 1962 by Josephson (1962 <I>Phys. Lett.</I> <A HREF='http://dx.doi.org/10.1016/0031-9163(62)91369-0'> <B>1</B> 251–3</A>) and observed by Anderson and Rowell (1963 <I>Phys. Rev. Lett.</I> <A HREF='http://dx.doi.org/10.1103/PhysRevLett.10.230'> <B>10</B> 230–2</A>) in 1963. The Josephson junction consists of two weakly coupled superconductors separated by a tunnel barrier or other weak link. A tiny electric current is able to flow between the superconductors as a supercurrent, without developing a voltage across them. At currents above the ‘critical current’ (maximum supercurrent), however, a voltage is developed. In 1964, Jaklevic <I>et al</I> (1964 <I>Phys. Rev. Lett.</I> <A HREF='http://dx.doi.org/10.1103/PhysRevLett.12.159'> <B>12</B> 159–60</A>) observed quantum interference between two Josephson junctions connected in series on a superconducting loop, giving birth to the dc SQUID. The essential property of the SQUID is that a steady increase in the magnetic flux threading the loop causes the critical current to oscillate with a period of one flux quantum. In today’s SQUIDs, using conventional semiconductor readout electronics, one can typically detect a change in Φ corresponding to 10<SUP>−6</SUP> Φ<SUB>0</SUB> in one second. Although early practical SQUIDs were usually made from bulk superconductors, for example, niobium or Pb-Sn solder blobs, today’s devices are invariably made from thin superconducting films patterned with photolithography or even electron lithography. An extensive descri

A STATISTICAL STUDY OF SOLAR ELECTRON EVENTS OVER ONE SOLAR CYCLE

Wang, Linghua,Lin, R. P.,Krucker, S&auml,m,Mason, Glenn M. IOP Publishing 2012 The Astrophysical journal Vol.759 No.1

<P>We survey the statistical properties of 1191 solar electron events observed by the WIND 3DP instrument from <1 keV to greater than or similar to 300 keVfor a solar cycle (1995 through 2005). After taking into account times of high background, the corrected occurrence frequency of solar electron events versus peak flux exhibits a power-law distribution over three orders of magnitude with exponents between -1.0 and -1.6 for different years, comparable to the frequency distribution of solar proton events, microflares, and coronal mass ejections (CMEs), but significantly flatter than that of soft X-ray (SXR) flares. At 40 keV (2.8 keV), the integrated occurrence rate above similar to 0.29 (similar to 330) cm(-2) s(-1) sr(-1) keV(-1) near 1 AU is similar to 1000 year(-1) (similar to 600 year(-1)) at solar maximum and similar to 35 year(-1) (similar to 25 year(-1)) at solar minimum, about an order of magnitude larger than the observed occurrence rate. We find these events typically extend over similar to 45 degrees in longitude, implying the occurrence rate over the whole Sun is similar to 10(4) year(-1) near solar maximum. The observed solar electron events have a 98.75% association with type III radio bursts, suggesting all type III bursts may be associated with a solar electron event. They have a close (similar to 76%) association with the presence of low-energy (similar to 0.02-2 MeV nucleon(-1)), He-3-rich (He-3/He-4 >= 0.01) ion emissions measured by the ACE ULEIS instrument. For these electron events, only similar to 35% are associated with a reported GOES SXR flare, but similar to 60% appear to be associated with a CME, with similar to 50% of these CMEs being narrow. These electrons are often detected down to below 1 keV, indicating a source high in the corona.</P>

Effect of anchoring groups in zinc phthalocyanine on the dye-sensitized solar cell performance and stability

Garcí,a-Iglesias, Miguel,Yum, Jun-Ho,Humphry-Baker, Robin,Zakeeruddin, Shaik M.,Pé,chy, Peter,Vá,zquez, Purificació,n,Palomares, Emilio,Gr&auml,tzel, Michael,Nazeeruddin, Moham Royal Society of Chemistry 2011 Chemical science Vol.2 No.6

<P>We have designed and developed an unsymmetrical zinc phthalocyanine (TT9) sensitizer that consists of three <I>tert</I>-butyl and two carboxylic acid groups that act as “<I>push</I>” and “<I>pull</I>”, respectively. The two carboxylic acid groups graft the sensitizer onto the semiconductor surface resulting in enhanced stability under heat and light compared to the similar unsymmetrical zinc phthalocyanine (TT1) sensitizer that consists of three <I>tert</I>-butyl and only one carboxylic acid groups. The solar cells containing the TT9 and TT1 sensitizers with non-volatile electrolyte were subjected to light soaking conditions at 60 °C. Under these conditions, the short circuit current of the TT1 sensitized solar cell after 1000 h decreases to half of its initial value where as the TT9 sensitized solar cell remained the same demonstrating the influence of number of anchoring groups on the stability of zinc phthalocyanine sensitized solar cells.</P> <P>Graphic Abstract</P><P>Phthalocyanine TT9 (red) grafts onto the semiconductor surface resulting in enhanced stability compared to TT1 (black). <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0sc00602e'> </P>

HARD X-RAY OBSERVATIONS OF A JET AND ACCELERATED ELECTRONS IN THE CORONA

Glesener, Lindsay,Krucker, S&auml,m,Lin, R. P. IOP Publishing 2012 The Astrophysical journal Vol.754 No.1

<P>We report the first hard X-ray observation of a solar jet on the limb with flare footpoints occulted, so that faint emission from accelerated electrons in the corona can be studied in detail. In this event on 2003 August 21, RHESSI observed a double coronal hard X-ray source in the pre-impulsive phase at both thermal and nonthermal energies. In the impulsive phase, the first of two hard X-ray bursts consists of a single thermal/nonthermal source coinciding with the lower of the two earlier sources, and the second burst shows an additional nonthermal, elongated source, spatially and temporally coincident with the coronal jet. Analysis of the jet hard X-ray source shows that collisional losses by accelerated electrons can deposit enough energy to generate the jet. The hard X-ray time profile above 20 keV matches that of the accompanying Type III and broadband gyrosynchrotron radio emission, indicating both accelerated electrons escaping outward along the jet path and electrons trapped in the flare loop. The double coronal hard X-ray source, the open field lines indicated by Type III bursts, and the presence of a small post-flare loop are consistent with significant electron acceleration in an interchange reconnection geometry.</P>

On the possibilities to use atmospheric reanalyses to evaluate the warming structure in the Arctic

Chung, C. E.,Cha, H.,Vihma, T.,R&auml,is&auml,nen, P.,Decremer, D. Copernicus GmbH 2013 Atmospheric chemistry and physics Vol.13 No.22

<P>Abstract. There has been growing interest in the vertical structure of the recent Arctic warming. We investigated temperatures at the surface, 925, 700, 500 and 300 hPa levels in the Arctic (north of 70° N) using observations and four reanalyses: ERA-Interim, CFSR, MERRA and NCEP II. For the period 1979-2011, the layers at 500 hPa and below show a warming trend in all seasons in all the chosen reanalyses and observations. Restricting the analysis to the 1998-2011 period, however, all the reanalyses show a cooling trend in the Arctic-mean 500 hPa temperature in autumn, and this also applies to both observations and the reanalyses when restricting the analysis to the locations with available IGRA radiosoundings. During this period, the surface observations mainly representing land areas surrounding the Arctic Ocean reveal no summertime trend, in contrast with the reanalyses whether restricted to the locations of the available surface observations or not. In evaluating the reanalyses with observations, we find that the reanalyses agree better with each other at the available IGRA sounding locations than for the Arctic average, perhaps because the sounding observations were assimilated into reanalyses. Conversely, using the reanalysis data only from locations matching available surface (air) temperature observations does not improve the agreement between the reanalyses. At 925 hPa, CFSR deviates from the other three reanalyses, especially in summer after 2000, and it also deviates more from the IGRA radiosoundings than the other reanalyses do. The CFSR error in summer T925 is due mainly to underestimations in the Canadian-Atlantic sector between 120° W and 0°. The other reanalyses also have negative biases in this longitude band. </P>