Coherent vortex structures and 3D enstrophy cascade

Existence of 2D enstrophy cascade in a suitable mathematical setting, and under suitable conditions compatible with 2D turbulence phenomenology, is known both in the Fourier and in the physical scales. The goal of this paper is to show that the same geometric condition preventing the formation of singularities - 1/2-H\"older coherence of the vorticity direction - coupled with a suitable condition on a modified Kraichnan scale, and under a certain modulation assumption on evolution of the vorticity, leads to existence of 3D enstrophy cascade in physical scales of the flow.Comment: 15 pp; final version -- to appear in CM

Spin paramagnetism in d-wave superconductors

The Ginzburg-Landau equations are derived from the microscopic theory for clean layered superconductors with $d_{x^2-y^2}$ pairing symmetry, including the Pauli paramagnetism effect. The upper critical field $H_{c2}$ parallel to the $c$ axis is calculated. A comparison with the experimental data for YBCO suggests that, relative to the orbital effect, the Pauli paramagnetism contribution to $H_{c2}$ is significant. The reversible magnetization $M$ in high magnetic fields is also calculated, showing strong temperature dependence of the slope $dM/dH$, as a consequence of the spin paramagnetism. A simple expression for the high temperature spin susceptibility is derived, in a good agreement with the Knight shift measurements on YBCO.Comment: 8 pages, 3 figures; minor changes are included; reference 35 is added; shorter version will be published in Phys. Rev. B, scheduled issue 01 July 200

Immunoreactivity to food antigens in patients with early rheumatoid arthritis

Uloga izmenjene crevne mukoze kao osnove nastanka autoimunosti u reumatoidnom artritisu (RA) još uvek nije razjašnjena. Kod bolesnika sa poodmaklim RA se mogu otkriti antitela na različite antigene iz hrane. Poseban značaj pridaje se IgG klasi ovih antitela jer aktivacija njihovih receptora (CD16/ FcγIIIR) na ćelijama imunskog sistema može imati veoma raznovrsne efekte. Nije poznato zašto postoji povišena imunoreaktivnost na antigene hrane kod bolesnika sa RA. Kao jedan od mogućih uzroka povišene imunoreaktivnosti na svakodnevne antigene iz hrane spominje se i enzim dipeptidil peptidaza IV (DPPIV). Ovaj enzim menja aktivnost biološki aktivnih peptida, a kao jedna od najvažnijih uloga ove peptidaze navodi se njen doprinos aktivaciji T limfocita i pokretanje imunskog odgovora. Brojna literatura opisuje serumsku aktivnost i ekspresiju DPPIV u hroničnom reumatoidnom artiritsu, ali nema puno podataka o ulozi ovog enzima u patogenezi ranog RA. Rad je imao za cilj da se prouči moguća povezanost između humoralne i ćelijske imunoreaktivnosti na antigene prisutne u namirnicama (glijadin, proteini kravljeg mleka i fitohemaglutinin) sa aktivnošću bolesti u obolelih od ranog, nelečenog RA. Dodatno, cilj je bio i da se odredi serumska aktivnost i ekspresija DPPIV na mononuklearnim ćelijama krvi kod pacijenata sa RA i da se utvrdi njihova moguća povezanost sa kliničkim pokazateljima bolesti. Ispitivana je i ekspresija IgG receptora na površini imunokompetentnih ćelija. Studija preseka obuhvatila je 50 bolesnika sa ranim, nelečenim RA, kao i 100 osoba u tri kontrolne grupe. U prvoj kontrolnoj grupi bilo je 30 obolelih od degenerativnih bolesti zglobova i kičme, uskladjenih po polu i po starosti sa obolelima od RA. Drugu kontrolnu grupu je činilo 40 zdravih ispitanika, a treću 30 bolesnika sa dugotrajnim RA (bolest trajala duže od 5 god) koja je učestvovala samo u ispitivanju ekspresije i serumske aktivnosti DPPIV...The potential role of changed gut mucosa as a basis for development of autoimmunity in rheumatoid arthritis (RA) has been assessed, but still remains unclear. Antibodies to food antigens were detected in chronic RA, with the special emphasis on IgG class of antibodies, because the activation of their receptors (CD16/FcγIIIR) on many different immune cells can result in various effects. As a potential cause of this immunoreactivity to food antigens, the enzyme dipeptidyl peptidase IV (DPPIV/CD26) is mentioned. DPPIV/CD26 changes activity of biologically active peptides, but one of the most important roles of this enzyme is activation of T lymphocytes and immune regulation. The majority of published data deals with chronic, established RA disease. However, little is known about the possible role of DPPIV/CD26 in the pathogenesis of early RA. The aim of this study was to investigate possible relationship between humoral/cellular immunity to food antigens and disease activity in treatment naive patients with early RA (eRA). Moreover, the aim of this study was to determine the serum activity of DPPIV, its expression on peripheral blood mononuclear cells (PBMC) and to assess possible correlations with disease activity (DAS28) in untreated patients with eRA. Furthermore, expression of CD16 on immunocompetent cells of peripheral blood and its possible relation to food antigens was examined. Study included 50 patients with early, untreated RA, and 100 persons in three control groups. First control group consisted of 30 patients with osteoarthritis, matched by age and gender. Second control group included 40 healthy volunteers and third control group consisted of 30 patients with chronic RA (tested only for DPPIV serum activity and expression). ELISA tests were used to determine the levels of IgA, IgG and IgM antibodies to gliadin and cow’s milk proteins (CMP), MTT test was used for the determination of the stimulation of lymphocyte proliferation. Determination of subpopulations (CD16, CD56, CD26) of immunocompetent cells was performed by flow cytometry. Serum activity of DPPIV was determined by the direct photometric method..

Quasiparticle energy spectrum in ferromagnetic Josephson weak links

The quasiparticles energy spectrum in clean ferromagnetic weak links between conventional superconductors is calculated. Large peaks in DOS, due to a special case of Andreev reflection at the ferromagnetic barrier, correspond to spin-splitt bound states. Their energies are obtained as a function of the barrier thickness, exchange field strength, and of the macroscopic phase difference $\phi$ at the link, related to the Josephson current. In the ground state, $\phi$ can be 0 or $\pi$, depending on the ferromagnetic barrier influence. Conditions for the appearence of the zero-energy bound states (ZES) and for the spin polarized ground state (SPGS) are obtained analytically. It is shown that ZES appear only outside the weak link ground state.Comment: 11 pages, 6 figure

In situ calibration of magnetic field coils using free-induction decay of atomic alignment

We propose a precision method for the in situ calibration of a three-axis coil system based on the free-induction decay of spin-aligned atoms. In addition, we present a simple and efficient method for measuring the three-vector components of a residual magnetic field

Topological enslavement in evolutionary games on correlated multiplex networks

Governments and enterprises strongly rely on incentives to generate favorable outcomes from social and strategic interactions between individuals. The incentives are usually modeled by payoffs in evolutionary games, such as the prisoner's dilemma or the harmony game, with imitation dynamics. Adjusting the incentives by changing the payoff parameters can favor cooperation, as found in the harmony game, over defection, which prevails in the prisoner's dilemma. Here, we show that this is not always the case if individuals engage in strategic interactions in multiple domains. In particular, we investigate evolutionary games on multiplex networks where individuals obtain an aggregate payoff. We explicitly control the strength of degree correlations between nodes in the different layers of the multiplex. We find that if the multiplex is composed of many layers and degree correlations are strong, the topology of the system enslaves the dynamics and the final outcome, cooperation or defection, becomes independent of the payoff parameters. The fate of the system is then determined by the initial conditions

Influence of nutrient substrates on the expression of cellulases in Cerambyx cerdo L. (Coleoptera: Cerambycidae) larvae

The expression and distribution of digestive cellulases along the midgut of Cerambyx cerdo larvae were analyzed for the first time and are presented in this article. Four groups of larvae were examined: larvae developed in the wild; larvae taken from the wild and successively reared on an artificial diet based on polenta; and larvae hatched in the laboratory and reared on two different artificial diets. Seven endocellulase and seven β-D-glucosidase isoforms were detected in all midgut extracts of C. cerdo with a zymogram after native PAGE. We observed that C. cerdo larvae are capable of producing cellulase isoforms with different PAGE mobilities depending on the nutrient substrate. From our findings it can be assumed that, depending on the distribution of endocellulase and β-D-glucosidase, cellulose molecules are first fragmented in the anterior and middle midgut by endo-β-1,4-glucanase; subsequently, the obtained fragments are broken down by β-D-glucosidase mostly in middle midgut