1,963 research outputs found
Un pequeño Oso de las Cavernas (Ursus rossicus) del Sur de Siberia, Rusia BARYSHNIKOV, G.
[Abstract] The skull, mandibles and cheek teeth of U. Rossicus from four localities of the South Siberia are examined. This species inhabited the steppe regions in early Middle and Late Pleistocene. By odontological characters it is more close to U. r. Rossicus from Krasnodar, than to U. Rossicus uralensis from Kizel Cave in Ural. Discriminant analysis, based on measurements of lower cheek teeth of the cave bears from seven sites of Europe and Siberia, demonstrated that U. Rossicus most resembles morphometrically U. Savini . As a result of cladistic analysis employed 17 characters of skull, limb bones, and dentition, the phylogenetic tree has been obtained for 7 species of the genus U r s u s . A four species of the cave bears are included in the subgenus Spelearctos: U. savini, U. rossicus, U. deningeri and U. spelaeu
Relations between the aromaticity and magnetic dipole transitions in the electronic spectra of hetero[8]circulenes
Magnetically induced current densities have been calculated at the second-order MOller-Plesset perturbation theory (MP2) level for seven hetero[8]circulenes and their dicationic and dianionic forms. Calculations of the magnetic dipole transition moments have also been carried out at the algebraic diagrammatic construction (ADC(2)) and the second-order approximate coupled-cluster (CC2) levels. The calculations show that the degree of aromaticity and the size of the magnetic dipole transition moment of the lowest magnetic-dipole allowed excited state are related. We show that neutral hetero[8]circulenes are weakly antiaromatic when the first excited state with a large magnetic dipole transition moment of 10-16 a.u. lies at high energies (approximate to 2.8-3.5 eV). For the dications, this transition often lies at much lower energies. Hetero[8]circulene dications with large magnetic dipole transition moments are strongly antiaromatic. The lowest excited states of the hetero[8]circulene dianions have very small magnetic dipole transition moments implying that they are aromatic.Peer reviewe
First-principles method for calculating the rate constants of internal-conversion and intersystem-crossing transitions
A method for calculating the rate constants for internal-conversion (k(IC)) and intersystem-crossing (k(ISC)) processes within the adiabatic and Franck-Condon (FC) approximations is proposed. The applicability of the method is demonstrated by calculation of k(IC) and k(ISC) for a set of organic and organometallic compounds with experimentally known spectroscopic properties. The studied molecules were pyrromethene-567 dye, psoralene, hetero[8]circulenes, free-base porphyrin, naphthalene, and larger polyacenes. We also studied fac-Alq(3) and fac-Ir(ppy)(3), which are important molecules in organic light emitting diodes (OLEDs). The excitation energies were calculated at the multi-configuration quasi-degenerate second-order perturbation theory (XMC-QDPT2) level, which is found to yield excitation energies in good agreement with experimental data. Spin-orbit coupling matrix elements, non-adiabatic coupling matrix elements, Huang-Rhys factors, and vibrational energies were calculated at the time-dependent density functional theory (TDDFT) and complete active space self-consistent field (CASSCF) levels. The computed fluorescence quantum yields for the pyrromethene-567 dye, psoralene, hetero[8]circulenes, fac-Alq(3) and fac-Ir(ppy)(3) agree well with experimental data, whereas for the free-base porphyrin, naphthalene, and the polyacenes, the obtained quantum yields significantly differ from the experimental values, because the FC and adiabatic approximations are not accurate for these molecules.Peer reviewe
Dobrushin-Kotecky-Shlosman theorem for polygonal Markov fields in the plane
We consider the so-called length-interacting Arak-Surgailis polygonal Markov
fields with V-shaped nodes - a continuum and isometry invariant process in the
plane sharing a number of properties with the two-dimensional Ising model. For
these polygonal fields we establish a low-temperature phase separation theorem
in the spirit of the Dobrushin-Kotecky-Shlosman theory, with the corresponding
Wulff shape deteremined to be a disk due to the rotation invariant nature of
the considered model. As an important tool replacing the classical cluster
expansion techniques and very well suited for our geometric setting we use a
graphical construction built on contour birth and death process, following the
ideas of Fernandez, Ferrari and Garcia.Comment: 59 pages, new version revised according to the referee's suggestions
and now publishe
Dianthracenylazatrioxa[8]circulene: synthesis, characterization and application in OLEDs
A soluble, green-blue fluorescent, pi-extended azatrioxa[8]circulene was synthesized by oxidative condensation of a 3,6-dihydroxycarbazole and 1,4-anthraquinone by using benzofuran scaffolding. This is the first circulene to incorporate anthracene within its carbon framework. Solvent-dependent fluorescence and bright green electroluminescence accompanied by excimer emission are the key optical properties of this material. The presence of sliding pi-stacked columns in the single crystal of dianthracenylazatrioxa[8]circulene is found to cause a very high electron-hopping rate, thus making this material a promising n-type organic semiconductor with an electron mobility predicted to be around 2.26 cm(2) V-1 s(-1). The best organic light-emitting diode (OLED) device based on the dianthracenylazatrioxa[8]circulene fluorescent emitter has a brightness of around 16 000 Cd m(-2) and an external quantum efficiency of 3.3 %. Quantum dot-based OLEDs were fabricated by using dianthracenylazatrioxa[8]circulene as a host matrix material.Peer reviewe
Hyperbolicity Measures "Democracy" in Real-World Networks
We analyze the hyperbolicity of real-world networks, a geometric quantity
that measures if a space is negatively curved. In our interpretation, a network
with small hyperbolicity is "aristocratic", because it contains a small set of
vertices involved in many shortest paths, so that few elements "connect" the
systems, while a network with large hyperbolicity has a more "democratic"
structure with a larger number of crucial elements.
We prove mathematically the soundness of this interpretation, and we derive
its consequences by analyzing a large dataset of real-world networks. We
confirm and improve previous results on hyperbolicity, and we analyze them in
the light of our interpretation.
Moreover, we study (for the first time in our knowledge) the hyperbolicity of
the neighborhood of a given vertex. This allows to define an "influence area"
for the vertices in the graph. We show that the influence area of the highest
degree vertex is small in what we define "local" networks, like most social or
peer-to-peer networks. On the other hand, if the network is built in order to
reach a "global" goal, as in metabolic networks or autonomous system networks,
the influence area is much larger, and it can contain up to half the vertices
in the graph. In conclusion, our newly introduced approach allows to
distinguish the topology and the structure of various complex networks
The Study of Ethanol Extracts Composition of Organic (Kachkulnya Lake) and Organomineral (Barchin Lake) Sapropels from Novosibirsk Region
Изучена экстракция сапропелей Новосибирской области органического (оз. Качкульня) и
органоминерального (оз. Барчин) типов этанолом при варьировании температуры процесса.
Повышение температуры от 50 до 200 °C приводит к увеличению выхода экстрактов в 19,0 и
13,7 раз для сапропелей органического и органоминерального типов соответственно.
Методами ИК-спектроскопии и хромато-масс-спектрометрии установлен состав полученных
экстрактов. Продукты из сапропеля органического типа содержат 68,1 % этиловых
эфиров, преимущественно жирных кислот с числом атомов углерода в молекуле от 18 до 29.
В экстрактах сапропелей органоминерального типа относительное содержание этиловых
эфиров составляет 43,6 %, в состав которых кроме этиловых эфиров жирных кислот входят
в значительных количествах этиловые эфиры окси- и гидроксикислот. Отличительной
особенностью экстрактов сапропеля органоминерального типа является наличие в нем
углеводов и соединений, включающих в свой состав фурановый циклThe extraction of sapropels of organic type (Kachkulnya Lake) and organo-mineral type (Barchin
Lake) from Novosibirsk region by ethanol at a variation of process temperature was studied. It was
shown that the rising of the temperature from 50 °C to 200 °C results in an increase the yields of
extracts by 19,0 and 13,7 times for sapropels organic and organo-mineral -types respectively
The composition of obtained extracts was established by IR and GC – MC methods. Products from
sapropel organic type contained 68,1 % ethyl esters, mainly of fatty acids with carbon atoms in the
molecule are from 18 to 29 numbers. It was established that relative content of ethyl esters in extract of
organo-mineral type sapropel was 43,6 %, they have a significant amounts of ethyl esters of hydroxy –
and oxyacids. A distinctive feature of the ethanol extract from organo-mineral type sapropel is the
presence of carbohydrates and compounds containing a furan rin
Differences and overlap in self-reported symptoms of bipolar disorder and borderline personality disorder
Background: Differential diagnosis between bipolar disorder (BD) and borderline personality disorder (BPD) is often challenging due to some overlap in symptoms and comorbidity of disorders. We investigated correlations in self-reported symptoms of BD and BPD in screening questionnaires at the levels of both total scores and individual items and explored overlapping dimensions. Methods: The McLean Screening Instrument (MSI) for BPD and the Mood Disorder Questionnaire (MDQ) for BD were filled in by patients with unipolar and bipolar mood disorders (n = 313) from specialized psychiatric care within a pilot study of the Helsinki University Psychiatric Consortium. Pearson's correlation coefficients between total scores and individual items of the MSI and the MDQ were estimated. Relationships between MDQ and MSI were evaluated by exploratory factor analysis (EFA). Results: The correlation between total scores of the MDQ and MSI was moderate (r = 0.431, P <0.001). Significant correlations were found between the MSI items of "impulsivity'' and "mood instability'' and all MDQ items (P <0.01). In the EFA, the MSI "impulsivity'' and "mood instability'' items had significant cross-loadings (0.348 and 0.298, respectively) with the MDQ factor. The MDQ items of "irritability'', "flight of thoughts'' and "distractibility'' (0.280, 0.210 and 0.386, respectively) cross-loaded on the MSI factor. Conclusions: The MDQ and MSI items of "affective instability'', "impulsivity'', "irritability'', "flight of thoughts'' and "distractibility'' appear to overlap in content. The other scale items are more disorder-specific, and thus, may help to distinguish BD and BPD. (C) 2015 Elsevier Masson SAS. All rights reserved.Peer reviewe
Second order analysis of geometric functionals of Boolean models
This paper presents asymptotic covariance formulae and central limit theorems
for geometric functionals, including volume, surface area, and all Minkowski
functionals and translation invariant Minkowski tensors as prominent examples,
of stationary Boolean models. Special focus is put on the anisotropic case. In
the (anisotropic) example of aligned rectangles, we provide explicit analytic
formulae and compare them with simulation results. We discuss which information
about the grain distribution second moments add to the mean values.Comment: Chapter of the forthcoming book "Tensor Valuations and their
Applications in Stochastic Geometry and Imaging" in Lecture Notes in
Mathematics edited by Markus Kiderlen and Eva B. Vedel Jensen. (The second
version mainly resolves minor LaTeX problems.
Optimization of supply diversity for the self-assembly of simple objects in two and three dimensions
The field of algorithmic self-assembly is concerned with the design and
analysis of self-assembly systems from a computational perspective, that is,
from the perspective of mathematical problems whose study may give insight into
the natural processes through which elementary objects self-assemble into more
complex ones. One of the main problems of algorithmic self-assembly is the
minimum tile set problem (MTSP), which asks for a collection of types of
elementary objects (called tiles) to be found for the self-assembly of an
object having a pre-established shape. Such a collection is to be as concise as
possible, thus minimizing supply diversity, while satisfying a set of stringent
constraints having to do with the termination and other properties of the
self-assembly process from its tile types. We present a study of what we think
is the first practical approach to MTSP. Our study starts with the introduction
of an evolutionary heuristic to tackle MTSP and includes results from extensive
experimentation with the heuristic on the self-assembly of simple objects in
two and three dimensions. The heuristic we introduce combines classic elements
from the field of evolutionary computation with a problem-specific variant of
Pareto dominance into a multi-objective approach to MTSP.Comment: Minor typos correcte
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