LIME - a flexible, non-LTE line excitation and radiation transfer method for millimeter and far-infrared wavelengths

We present a new code for solving the molecular and atomic excitation and radiation transfer problem in a molecular gas and predicting emergent spectra. This code works in arbitrary three dimensional geometry using unstructured Delaunay latices for the transport of photons. Various physical models can be used as input, ranging from analytical descriptions over tabulated models to SPH simulations. To generate the Delaunay grid we sample the input model randomly, but weigh the sample probability with the molecular density and other parameters, and thereby we obtain an average grid point separation that scales with the local opacity. Our code does photon very efficiently so that the slow convergence of opaque models becomes traceable. When convergence between the level populations, the radiation field, and the point separation has been obtained, the grid is ray-traced to produced images that can readily be compared to observations. Because of the high dynamic range in scales that can be resolved using this type of grid, our code is particularly well suited for modeling of ALMA data. Our code can furthermore deal with overlapping lines of multiple molecular and atomic species.Comment: 13 pages, 12 figures, Accepted by A&A on 06/08/201

Слабка властивість Дарбу і перехідність лінійних відображень у топологічних векторних просторах

It is shown that every linear mapping on topological vector spaces always has weak Darboux property, therefore, it is continuous if and only if it is transitive. For finite-dimensional mapping $f$ with values in Hausdorff topological vector space the following conditions are equivalent: (i) $f$ is continuous; (ii) graph of $f$ is closed; (iii) kernel of $f$ is closed; (iv) $f$ is transition map.Показано, що кожне лінійне відображення в топологічних векторних просторах завжди має слабку властивість Дарбу, отже, буде неперервн

The leap of learning

This article seeks to elaborate the step of epistemological affirmation that exists within every movement of learning. My epistemological method is rooted in philosophical hermeneutics in contrast to empirical or rationalist traditions. I argue that any movement of learning is based upon an entry into a hermeneutical circle: one is thrown into, or leaps into, an interpretation which in some sense has to be temporarily affirmed or adopted in order to be either absorbed and integrated, or overcome and rejected. I illustrate this process through a retrieval of the concept of submission in pedagogy, particularly with reference to submission in Eastern traditions, as well as pre-modern Christian thought. These other traditions are introduced to contrast with the modern liberal Western perspective in which the role of submission has been almost entirely lost

Достатнi умови iснування точок симетричної квазiнеперервностi та клiковостi функцiй двох змiнних

It is established sufficient conditions under which for the function $f:X\times Y\to Z$ there is a residual in $X$ set $A$, such that the function $f$ is symmetrically quasi-continuous (cliquish) one with respect to $x$ at each point of the set $A\times Y$.Встановлено достатні умови, при яких для функції $f:X\times Y\to Z$ існує така залишкова в $X$ множина $A$, що функція $f$ симетрично квазінеперервна (клікова) відносно $x$ в кожній точці множини $A\times Y$

Nambu-Goto string with massive ends at finite temperature

It is shown that the critical (or deconfinement) temperature for the Nambu-Goto string connecting the point-like masses (quarks) does not depend on the value of these masses. This temperature turns out to be the same as that in the case of string with fixed ends (infinitely heavy immobile quarks).Comment: LaTex file, 8 page

Regularizing Property of the Maximal Acceleration Principle in Quantum Field Theory

It is shown that the introduction of an upper limit to the proper acceleration of a particle can smooth the problem of ultraviolet divergencies in local quantum field theory. For this aim, the classical model of a relativistic particle with maximal proper acceleration is quantized canonically by making use of the generalized Hamiltonian formalism developed by Dirac. The equations for the wave function are treated as the dynamical equations for the corresponding quantum field. Using the Green's function connected to these wave equations as propagators in the Feynman integrals leads to an essential improvement of their convergence properties.Comment: 9 pages, REVTeX, no figures, no table

Casimir energy of a non-uniform string

The Casimir energy of a non-uniform string built up from two pieces with different speed of sound is calculated. A standard procedure of subtracting the energy of an infinite uniform string is applied, the subtraction being interpreted as the renormalization of the string tension. It is shown that in the case of a homogeneous string this method is completely equivalent to the zeta renormalization.Comment: 11 pages, REVTeX, no figures and table

Pion form factor and QCD sum rules: case of axial current

We present an analysis of QCD sum rules for pion form factor in next-to-leading order of perturbation theory for the case of axial-vector pion currents. The theoretical predictions for Q^2-dependence of pion form factor are in good agreement with available experimental data. It is shown, that NLO corrections are large in this case and should be taken into account in rigorous theoretical analysis.Comment: LaTeX file, 10 pages, 5 figures, v2: added check of Ward identity constrains at Q^2=0, the continuum thresholds are determined to satisfy F_{\pi}(0)=1 condition with NLO accuracy, what led to \approx 10% reduction of our numerical estimates, references adde

Boundary terms in Nambu-Goto string action

We investigate classical strings defined by the Nambu-Goto action with the boundary term added. We demonstrate that the latter term has a significant bearing on the string dynamics. It is confirmed that new action terms that depend on higher order derivatives of string coordinates cannot be considered as continuous perturbations from the starting string functional. In the case the boundary term reduces to the Gauss-Bonnet term, a stability analysis is performed on the rotating rigid string solution. We determined the most generic solution that the fluctuations grow to. Longitudinal string excitations are found. The Regge trajectories are nonlinear.Comment: 9 LaTeX pages and 3 PostScript figures (uuencoded), preprint TPJU-15/9

Mass spectra of doubly heavy Omega_QQ' baryons

We evaluate the masses of baryons composed of two heavy quarks and a strange quark with account for spin-dependent splittings in the framework of potential model with the KKO potential motivated by QCD with a three-loop beta-function for the effective charge consistent with both the perturbative limit at short distances and linear confinement term at long distances between the quarks. The factorization of dynamics is supposed and explored in the nonrelativistic Schroedinger equation for the motion in the system of two heavy quarks constituting the doubly heavy diquark and the strange quark interaction with the diquark. The limits of approach, its justification and uncertainties are discussed. Excited quasistable states are classified by the quantum numbers of heavy diquark composed by the heavy quarks of the same flavor.Comment: 14 pages, revtex4-file, 3 eps-figures, 5 tables, typos correcte