1,457 research outputs found
Політичні стереотипи та стереотипізація мислення: роль та значення у системі іміджевих комунікацій
Всебічно розглянуто особливості стереотипізації мислення як важливого чинника
у процесі сприйняття та аналізу особою або групою осіб суспільно-політичної
дійсності.
Досліджено природу, джерела та механізми формування політичних стереотипів
та показано їх роль і значення у системі іміджевих комунікацій. Наголошено на
необхід-
ності аналізу існуючої системи стереотипів при створенні іміджу суб’єкта політики.There have been thoroughly examined peculiarities of stereotyping of thinking as an
important factor in the process of perception and analysis of socio-political reality by a
person
or a group of people. There have been investigated the nature, sources and
mechanism of
political stereotypes formation and showed their role and meaning in the system if
image
communications. There has been put an emphasis on the necessity of analysis of the
existing
system of stereotypes while creating the image of a subject of policy
Щоденники експедиційної роботи Григорія Дем'яна (Вступна стаття та підготовка текстів Василя Сокола)
The interaction between S(-II) and ferric oxides exerts a major control for the sulphur and iron cycle and in particular for the carbon and electron flow in many aquatic systems. It is regarded to be a key reaction leading ultimately to pyrite formation, the pathways still remaining unresolved. We have studied the reaction between lepidocrocite (γ-FeOOH, 21–42 mmol L−1) and dissolved S(-II) (3–9 mmol L−1) in batch experiments at pH 7 in a glove box using TEM, XRD, Mössbauer spectroscopy, and wet chemistry extraction to explore the nanocrystalline products forming at different time steps in close contact to the lepidocrocitesurface. S(0) and acid extractable Fe(II) (Fe(II)HCl) were the main products detected by wet chemistry extraction. The reaction could be divided into three steps: a rapid (<15 min) consumption of dissolved S(-II), formationof S(0) and the build-up of an Fe(II)HCl pool. Then in the absence of dissolved S(-II) concentrations of S(0) and Fe(II)HCl increased only slightly. TEM measurements revealed the occurrence of a mackinawite rim covering the lepidocrocite crystals and being separated from the lepidocrocitesurface by an interfacial magnetite layer that can be regarded as a steady state product of the interaction between lepidocrocite and mackinawite. A significant fraction of Fe(II) was formed in excess to FeS within the first 2 h. The amount of this fraction increased with decreasing ratio between dissolved S(-II) concentration and the concentration ofsurface sites, which we attributed to a kinetic decoupling of S(-II) oxidation and Fe(II) detachment from the lepidocrocitesurface. At low ratios, S(-II) seems to transfer electrons to lepidocrocite faster then stoichiometric amounts of FeS could. After 2 days Fe(II)HCl and S(0) started to decrease resulting in pyrite formation accompanied by traces of magnetite. TEM measurements indicated that mackinawite completely dissolved and precipitation of pyrite occurred dislocated from the lepidocrocitesurface. The absence of dissolved sulphide under these conditions suggest that excess Fe(II) is involved in the formationof polysulphides which are key precursors during pyrite formation. We propose that the occurrence of excess Fe(II) is a common phenomenon particularly in low sulphide – high iron environments attributing significant reactivity to ferric (hydr)oxide
Site-selective measurement of coupled spin pairs in an organic semiconductor
From organic electronics to biological systems, understanding the role of intermolecular interactions between spin pairs is a key challenge. Here we show how such pairs can be selectively addressed with combined spin and optical sensitivity. We demonstrate this for bound pairs of spin-triplet excitations formed by singlet fission, with direct applicability across a wide range of synthetic and biological systems. We show that the site sensitivity of exchange coupling allows distinct triplet pairs to be resonantly addressed at different magnetic fields, tuning them between optically bright singlet (S=0) and dark triplet quintet (S=1,2) configurations: This induces narrow holes in a broad optical emission spectrum, uncovering exchange-specific luminescence. Using fields up to 60 T, we identify three distinct triplet-pair sites, with exchange couplings varying over an order of magnitude (0.3–5 meV), each with its own luminescence spectrum, coexisting in a single material. Our results reveal how site selectivity can be achieved for organic spin pairs in a broad range of systems
General relativity as an effective field theory: The leading quantum corrections
I describe the treatment of gravity as a quantum effective field theory. This
allows a natural separation of the (known) low energy quantum effects from the
(unknown) high energy contributions. Within this framework, gravity is a well
behaved quantum field theory at ordinary energies. In studying the class of
quantum corrections at low energy, the dominant effects at large distance can
be isolated, as these are due to the propagation of the massless particles
(including gravitons) of the theory and are manifested in the
nonlocal/nonanalytic contributions to vertex functions and propagators. These
leading quantum corrections are parameter-free and represent necessary
consequences of quantum gravity. The methodology is illustrated by a
calculation of the leading quantum corrections to the gravitational interaction
of two heavy masses.Comment: 34 pages, Latex, UMHEP-40
Thyroid Hormones Regulate Selenoprotein Expression and Selenium Status in Mice
Impaired expression of selenium-containing proteins leads to perturbed thyroid hormone (TH) levels, indicating the central importance of selenium for TH homeostasis. Moreover, critically ill patients with declining serum selenium develop a syndrome of low circulating TH and a central downregulation of the hypothalamus-pituitary-thyroid axis. This prompted us to test the reciprocal effect, i.e., if TH status would also regulate selenoprotein expression and selenium levels. To investigate the TH dependency of selenium metabolism, we analyzed mice expressing a mutant TH receptor α1 (TRα1+m) that confers a receptor-mediated hypothyroidism. Serum selenium was reduced in these animals, which was a direct consequence of the mutant TRα1 and not related to their metabolic alterations. Accordingly, hyperthyroidism, genetically caused by the inactivation of TRβ or by oral TH treatment of adult mice, increased serum selenium levels in TRα1+m and controls, thus demonstrating a novel and specific role for TRα1 in selenium metabolism. Furthermore, TH affected the mRNA levels for several enzymes involved in selenoprotein biosynthesis as well as serum selenoprotein P concentrations and the expression of other antioxidative selenoproteins. Taken together, our results show that TH positively affects the serum selenium status and regulates the expression of several selenoproteins. This demonstrates that selenium and TH metabolism are interconnected through a feed-forward regulation, which can in part explain the rapid parallel downregulation of both systems in critical illness
Lock-in detection for pulsed electrically detected magnetic resonance
We show that in pulsed electrically detected magnetic resonance (pEDMR)
signal modulation in combination with a lock-in detection scheme can reduce the
low-frequency noise level by one order of magnitude and in addition removes the
microwave-induced non-resonant background. This is exemplarily demonstrated for
spin-echo measurements in phosphorus-doped Silicon. The modulation of the
signal is achieved by cycling the phase of the projection pulse used in pEDMR
for the read-out of the spin state.Comment: 4 pages, 2 figure
Elucidating the structural composition of a Fe-N-C catalyst by nuclear and electron resonance techniques
Fe–N–C catalysts are very promising materials for fuel cells and metal–air batteries. This work gives fundamental insights into the structural composition of an Fe–N–C catalyst and highlights the importance of an in‐depth characterization. By nuclear‐ and electron‐resonance techniques, we are able to show that even after mild pyrolysis and acid leaching, the catalyst contains considerable fractions of α‐iron and, surprisingly, iron oxide. Our work makes it questionable to what extent FeN4 sites can be present in Fe–N–C catalysts prepared by pyrolysis at 900 °C and above. The simulation of the iron partial density of phonon states enables the identification of three FeN4 species in our catalyst, one of them comprising a sixfold coordination with end‐on bonded oxygen as one of the axial ligands
Probing the wave function and dynamics of the quintet multiexciton state with coherent control in a singlet fission material
High-spin states play a key role in chemical reactions found in nature. In artificial molecular systems, singlet fission produces a correlated triplet-pair state, a spin-bearing excited state that can be harnessed for more efficient solar-energy conversion and photocatalysis. In particular, triplet-pair states with overall quintet character (total spin S=2) have been discovered, but many of the fundamental properties of these biexciton states remain unexplored. The net spin of these pair states makes spin-sensitive probes attractive for their characterization. Combined with their surprisingly long spin coherence (of order microseconds), this opens up techniques relying on coherent spin control. Here we apply coherent manipulation of triplet-pair states to (i) isolate their spectral signatures from coexisting free triplets and (ii) selectively couple quintet and triplet states to specific nuclear spins. Using this approach, we separate quintet and triplet transitions and extract the relaxation dynamics and hyperfine couplings of the fission-borne spin states. Our results highlight the distinct properties of correlated and free triplet excitons and demonstrate optically induced nuclear spin polarization by singlet fission
New Approach for Measuring at Future -Factories
It is suggested that the measurements of hadronic invariant mass ()
distributons in the inclusive decays can be
useful in extracting the CKM matrix element . We investigated
hadronic invariant mass distributions within the various theoretical models of
HQET, FAC and chiral lagrangian as well as ACCMM model. It is also emphasized
that the distribution even at the region in the inclusive
are effetive in selecting the events, experimentally viable at
the future asymmetric factories, with better theoretical understandings.Comment: 11 pages not including 1 figur
Generalized Gordon Identities, Hara Theorem and Weak Radiative Hyperon Decays
It is shown that an alternative form of the parity-nonconserving (PNC)
transition electromagnetic current resolves partly a puzzle with the Hara
theorem. New formulation of it has allowed PNC weak radiative hyperon
transitions of the charged hyperons and
revealing hitherto unseen transition
toroid dipole moment.Comment: LaTex, 7 pages, 2 tables added, text also change
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