6,498 research outputs found
A Ballistic Graphene Cooper Pair Splitter
We report an experimental study of Cooper pair splitting in an encapsulated
graphene based multiterminal junction in the ballistic transport regime. Our
device consists of two transverse junctions, namely the
superconductor/graphene/superconductor and the normal metal/graphene/normal
metal junctions. In this case, the electronic transport through one junction
can be tuned by an applied bias along the other. We observe clear signatures of
Cooper pair splitting in the local as well as nonlocal electronic transport
measurements. Our experimental data can be very well described by using a
modified Octavio-Tinkham-Blonder-Klapwijk model and a three-terminal beam
splitter model
Nonlinear thermoelectric effects in high-field superconductor-ferromagnet tunnel junctions
Thermoelectric effects result from the coupling of charge and heat transport,
and can be used for thermometry, cooling and harvesting of thermal energy. The
microscopic origin of thermoelectric effects is a broken electron-hole
symmetry, which is usually quite small in metal structures, and vanishes at low
temperatures. We report on a combined experimental and theoretical
investigation of thermoelectric effects in superconductor/ferromagnet hybrid
structures. We investigate the depencence of thermoelectric currents on the
thermal excitation, as well as on the presence of a dc bias voltage across the
junction. Large thermoelectric effects are observed in
superconductor/ferromagnet and superconductor/normal-metal hybrid structures.
The spin-independent signals observed under finite voltage bias are shown to be
reciprocal to the physics of superconductor/normal-metal microrefrigerators.
The spin-dependent thermoelectric signals in the linear regime are due to the
coupling of spin and heat transport, and can be used to design more efficient
refrigeratorsComment: 11 pages, submitted to Beilstein Journal of Nanotechnolog
BeppoSAX observations of the quasar Markarian 205
We present the first BeppoSAX observation (0.1 to 220 keV) of the quasar Mrk
205. We have searched for the unusual Fe line profile claimed in the XMM-Newton
spectrum which has been widely discussed in recent literature. We find no
evidence for a broad, ionized Fe line component in our data. We detect for the
first time a Compton hump in this object. Besides, when this component is
included in the fit, the line strength diminishes, in agreement with a recent
re-analysis of the XMM-Newton data, but with better constraints on the
reflection component thanks to the PDS instrument (15-220 keV). We interpret
this fact as another indication for illumination of a distant and cold material
rather than reprocessing in the highly ionized inner parts of an accretion
disk. We cannot constrain the presence of a high energy cutoff but we confirm
the existence of a variable soft excess (one year timescale).Comment: 13 pages, 12 figures, accepted for publication in A&
O znaÄenju i nekim kontekstima termina âautonomijaâ. Konceptualno istraĆŸivanje
The paper aims to analyse conceptually the meaning of the term âautonomyâ and to examine critically its relations with other ethical norms. The question posed is whether autonomy is a right, or an ability, or a capacity, or an achievement, and whether it ought to be distinguished from self-determination. It is shown that autonomy is an anthropological principle, and that self-determination as its manifestation is a human right. As to its relation with other ethical norms, it is shown that there are possible conflicts between a patientâs and his doctorâs autonomies, as well as between autonomy and the duty to protect life, and between autonomy and care, so that trust plays an important role. The author concludes that man is autonomous not if and only if he is able to determine himself, but rather that he has the right to determine himself because he is autonomous. This holds for everybody from their beginning to their end, irrespective of what they are able to do and the situation they may be in. Since every human being is autonomous, autonomy entails self-limitation, and so it does not mean independence, but interdependence. As to trust, autonomy is to be acknowledged, while trust is to be practiced, since autonomy is of people, while trust is in people.Cet article tente dâanalyser de maniĂšre conceptuelle la signification du terme dâautonomie et de questionner ses rapports avec dâautres normes Ă©thiques. La question est de savoir si lâautonomie est un droit, une facultĂ© ou une possibilitĂ©, et sâil faut la diffĂ©rencier de lâautodĂ©termination. Il est montrĂ© que lâautonomie est un principe anthropologique et que lâautodĂ©termination, qui en est sa manifestation, est un droit humain. En ce qui concerne ses rapports avec dâautres normes Ă©thiques, il est montrĂ© que dâautres conflits sont possibles, des conflits entre lâautonomie du patient et lâautonomie du mĂ©decin, entre lâautonomie et les devoirs de protection de la vie, mais aussi entre lâautonomie et les soins. Ainsi, un rĂŽle important revient Ă la confiance. Lâauteur conclut que lâhomme nâest pas autonome, si et seulement si, il est capable dâautodĂ©termination, mais câest bien parce quâil a un droit Ă lâautodĂ©termination quâil est autonome. Cela vaut pour chacun depuis ses dĂ©buts jusquâĂ ses fins, indĂ©pendamment de ce dont il est capable
de faire et de la situation dans laquelle il peut se trouver. Ătant donnĂ© que chaque ĂȘtre humain est autonome, lâautonomie entraĂźne Ă ses cĂŽtĂ©s lâautolimitation, de telle maniĂšre quâil ne sâagit pas dâindĂ©pendance mais dâinterdĂ©pendance. En ce qui concerne la confiance, lâautonomie doit ĂȘtre reconnue, et la confiance doit ĂȘtre pratiquĂ©e, car ce dont il sâagit câest dâautonomie des personnes, et câest bien en la personne que lâon a confiance.Der Beitrag gilt einer Analyse der Bedeutung des Terminus âAutonomieâ sowie einer kritischen PrĂŒfung seiner Beziehungen zu anderen ethischen Normen. Zu klĂ€ren ist, ob Autonomie ein Recht, eine FĂ€higkeit, ein Vermögen oder eine Errungenschaft darstellt und ob man zwischen Autonomie und Selbstbestimmung unterscheiden muss. Es wird gezeigt, dass Autonomie ein anthropologisches Prinzip ist und Selbstbestimmung als Manifestation von Autonomie ein menschliches Recht. Was die Beziehungen zu anderen ethischen Normen angeht, so zeigen sich mögliche ethische Konflikte zwischen Patienten- und Arztautonomie, zwischen Autonomie und der Pflicht
zum Lebensschutz und zwischen Autonomie und FĂŒrsorge, was der Norm des Vertrauens eine wichtige Rolle zuweist. Der Autor gelangt zu dem Ergebnis, dass der Mensch nicht deswegen noch dann autonom ist, wenn er sich selbst zu bestimmen in der Lage ist, sondern dass er das Recht zur Selbstbestimmung besitzt, weil er autonom ist. Dies gilt fĂŒr jedermann, unabhĂ€ngig von seinem Können oder seiner Lebenssituation, vom Anfang bis zum Ende seines Lebens. Da jedes menschliche Wesen in diesem Sinne autonom ist, impliziert Autonomie Selbstbegrenzung und somit nicht UnabhĂ€ngigkeit, sondern Interdependenz. Was die Norm des Vertrauens angeht, so muss Autonomie anerkannt, Vertrauen hingegen praktiziert werden. Denn: Autonomie gehört untrennbar zum Menschen, Vertrauen gilt dem Menschen.Älanak nastoji konceptualno analizirati znaÄenje termina âautonomijaâ i kritiÄki ispitati njegove odnose s drugim etiÄkim normama. Postavlja se pitanje je li autonomija pravo ili sposobnost ili moguÄnost te da li bi ju trebalo razlikovati od samoodreÄenja. Pokazuje se da je autonomija antropoloĆĄki princip te da je samoodreÄenje kao njezina manifestacija ljudsko pravo. Ć to se tiÄe njezina odnosa s drugim etiÄkim normama, pokazuje se da su moguÄi sukobi izmeÄu autonomije pacijenta i autonomije lijeÄnika, kao i izmeÄu autonomije i duĆŸnosti zaĆĄtite ĆŸivota te izmeÄu autonomije i skrbi, tako da vaĆŸnu ulogu igra povjerenje. Autor zakljuÄuje da Äovjek nije autonoman
ako i samo ako je sposoban za samoodreÄenje nego da ima pravo na samoodreÄenje zato ĆĄto je autonoman. To vaĆŸi za svakoga od njegova poÄetka do njegova kraja, bez obzira na to ĆĄto je sposoban uÄiniti i situaciju u kojoj se moĆŸe naÄi. BuduÄi da je svako ljudsko biÄe autonomno, autonomija za sobom povlaÄi samoograniÄavanje, tako da ne znaÄi nezavisnost, nego meÄuzavisnost. Ć to se tiÄe povjerenja, autonomiju treba priznavati, a povjerenje treba prakticirati zato ĆĄto se radi o autonomiji ljudi, a povjerenje se ima u ljude
Compton processes in the bright AGN MCG+8-11-11
We present preliminary results on the hard X-ray emission properties of the
Seyfert 1.5 galaxy MCG+8-11-11 as observed by INTEGRAL and SWIFT. All the
INTEGRAL IBIS/ISGRI data available up to October 2009 have been analyzed
together with two SWIFT/XRT snapshot observations performed in August and
October 2009, quasi-simultaneously to INTEGRAL pointed observations of
MCG+8-11-11. No correlation is observed between the hard X-ray flux and the
spectral slope, while the position of the high-energy cut-off is found to have
varied during the INTEGRAL observations. This points to a change in the
temperature of the Comptonising medium from a minimum value of kT = 30-50 keV
to values larger than 100-150 keV. There is no significant detection of Compton
reflection, with a 3 sigma upper limit of R < 0.2, and no line has been
detected at 112 keV, as previously claimed from HEAT observations (112 keV flux
F < 2.4e-4 ph/cm^2/s). The variability behaviour of MCG+8-11-11 is found to be
similar to that shown by IC 4329A, with different temperatures of the electron
plasma for similar flux levels of the source, while other bright Seyfert
galaxies present different variability patterns at hard X-rays, with spectral
changes correlated to flux variations (e.g. NGC 4151).Comment: 6 pages, 4 figures. Accepted for publication on PoS (contribution
PoS(INTEGRAL 2010)077), proceedings of the 8th INTEGRAL Workshop "The
Restless Gamma-ray Universe" (September 2010, Dublin, Ireland
High-energy emission from NGC 5506, the brightest hard X-ray Narrow Line Seyfert 1 galaxy
We present results on the hard X-ray emission of NGC 5506, the brightest
narrow line Seyfert 1 galaxy above 20 keV. All the recent observations by
INTEGRAL, Swift and Suzaku have been analysed and spectral analysis during nine
separated time periods has been performed. While flux variations by a factor of
2 were detected during the last 7 years, only moderate spectral variations have
been observed, with the hint of a hardening of the X-ray spectrum and a
decrease of the intrinsic absorption with time. Using Suzaku observations it is
possible to constrain the amount of Compton reflection to R = 0.6-1.0, in
agreement with previous results on the source. The signature of Comptonisation
processes can also be found in the detection of a high-energy cut-off during
part of the observations, at Ec = 40-100 keV. When a Comptonisation model is
applied to the Suzaku data, the temperature and the optical depth of the
Comptonising electron plasma are measured at kT = 60-80 keV and tau = 0.6-1.0,
respectively. The properties inferred for NGC 5506 in this study agree with
those based on other data sets for the same AGN, and fit the picture of NLS1
having in general lower high-energy cut-offs at hard X-rays than their broad
line equivalent.Comment: 8 pages, 3 figures, 1 table. Proceedings of the Workshop "Narrow-Line
Seyfert 1 Galaxies and Their Place in the Universe", Milano, April 4-6, 2011
(Proceedings of Science,
http://pos.sissa.it/cgi-bin/reader/conf.cgi?confid=126
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