618 research outputs found
Transport in the XX chain at zero temperature: Emergence of flat magnetization profiles
We study the connection between magnetization transport and magnetization
profiles in zero-temperature XX chains. The time evolution of the transverse
magnetization, m(x,t), is calculated using an inhomogeneous initial state that
is the ground state at fixed magnetization but with m reversed from -m_0 for
x0. In the long-time limit, the magnetization evolves into a
scaling form m(x,t)=P(x/t) and the profile develops a flat part (m=P=0) in the
|x/t|1/2 while it
expands with the maximum velocity, c_0=1, for m_0->0. The states emerging in
the scaling limit are compared to those of a homogeneous system where the same
magnetization current is driven by a bulk field, and we find that the
expectation values of various quantities (energy, occupation number in the
fermionic representation) agree in the two systems.Comment: RevTex, 8 pages, 3 ps figure
A helyi szintű klĂmastratĂ©giák megvalĂłsĂtásának akadályai
Gazdasági Élet és Társadalo
Magnetization distribution in the transverse Ising chain with energy flux
The zero-temperature transverse Ising chain carrying an energy flux j_E is
studied with the aim of determining the nonequilibrium distribution functions,
P(M_z) and P(M_x), of its transverse and longitudinal magnetizations,
respectively. An exact calculation reveals that P(M_z) is a Gaussian both at
j_E=0 and j_E not equal 0, and the width of the distribution decreases with
increasing energy flux. The distribution of the order-parameter fluctuations,
P(M_x), is evaluated numerically for spin-chains of up to 20 spins. For the
equilibrium case (j_E=0), we find the expected Gaussian fluctuations away from
the critical point while the critical order-parameter fluctuations are shown to
be non-gaussian with a scaling function Phi(x)=Phi(M_x/)=P(M_x)
strongly dependent on the boundary conditions. When j_E not equal 0, the system
displays long-range, oscillating correlations but P(M_x) is a Gaussian
nevertheless, and the width of the Gaussian decreases with increasing j_E. In
particular, we find that, at critical transverse field, the width has a
j_E^(-3/8) asymptotic in the j_E -> 0 limit.Comment: 8 pages, 5 ps figure
Formation of Liesegang patterns: Simulations using a kinetic Ising model
A kinetic Ising model description of Liesegang phenomena is studied using
Monte Carlo simulations. The model takes into account thermal fluctuations,
contains noise in the chemical reactions, and its control parameters are
experimentally accessible. We find that noisy, irregular precipitation takes
place in dimension d=2 while, depending on the values of the control
parameters, either irregular patterns or precipitation bands satisfying the
regular spacing law emerge in d=3.Comment: 7 pages, 8 ps figures, RevTe
Axon diversity of lamina I local-circuit neurons in the lumbar spinal cord
Spinal lamina I is a key area for relaying and integrating information from nociceptive primary afferents with various other sources of inputs. Although lamina I projection neurons have been intensively studied, much less attention has been given to local-circuit neurons (LCNs), which form the majority of the lamina I neuronal population. In this work the infrared light-emitting diode oblique illumination technique was used to visualize and label LCNs, allowing reconstruction and analysis of their dendritic and extensive axonal trees. We show that the majority of lamina I neurons with locally branching axons fall into the multipolar (with ventrally protruding dendrites) and flattened (dendrites limited to lamina I) somatodendritic categories. Analysis of their axons revealed that the initial myelinated part gives rise to several unmyelinated small-diameter branches that have a high number of densely packed, large varicosities and an extensive rostrocaudal (two or three segments), mediolateral, and dorsoventral (reaching laminae III–IV) distribution. The extent of the axon and the occasional presence of long, solitary branches suggest that LCNs may also form short and long propriospinal connections. We also found that the distribution of axon varicosities and terminal field locations show substantial heterogeneity and that a substantial portion of LCNs is inhibitory. Our observations indicate that LCNs of lamina I form intersegmental as well as interlaminar connections and may govern large numbers of neurons, providing anatomical substrate for rostrocaudal “processing units” in the dorsal horn
Derivation of the Matalon-Packter law for Liesegang patterns
Theoretical models of the Liesegang phenomena are studied and simple
expressions for the spacing coefficients characterizing the patterns are
derived. The emphasis is on displaying the explicit dependences on the
concentrations of the inner- and the outer-electrolytes. Competing theories
(ion-product supersaturation, nucleation and droplet growth, induced sol-
coagulation) are treated with the aim of finding the distinguishing features of
the theories. The predictions are compared with experiments and the results
suggest that the induced sol-coagulation theory is the best candidate for
describing the experimental observations embodied in the Matalon-Packter law.Comment: 9 pages, 7 figures, RevTe
A társadalmi klĂma változása Magyarországon
A klĂmaváltozás egy ideig elsĹ‘sorban a meteorolĂłgusok Ă©s a környezet vĂ©delmĂ©vel foglalkozĂł szakemberek számára volt fontos kĂ©rdĂ©s, mára azonban már az egyik legfontosabb társadalmi, gazdasági Ă©s politikai kĂ©rdĂ©ssĂ© vált. Ez a változás a „társadalmi klĂma változásának” nevezhetĹ‘. EzĂ©rt Ă©rthetĹ‘, hogy ma már ezzel a kĂ©rdĂ©ssel szinte minden szakterĂĽlet kĂ©pviselĹ‘i –köztĂĽk az orvosok is a szociolĂłgusok is –komolyan foglalkoznak. Magyarországon 2018 oktĂłbere Ă©s 2019 decembere között a klĂmaváltozás társadalom Ă©letĂ©ben betöltött szerepe megváltozott, Ă©s ezzel Magyarországon a „társadalmi klĂma változás” egy Ăşj szakaszához Ă©rkezett. Ennek a változásnak a vizsgálata azĂ©rt kĂĽlönösen fontos, mert a klĂmaváltozás ma már nem csupán egy termĂ©szeti jelensĂ©g, hanem egy olyan kĂ©rdĂ©s, amely a társadalom tagjait is komolyan foglalkoztatja, Ă©s amely a társadalom Ă©letĂ©ben az elkövetkezĹ‘ Ă©vekben meghatározĂł szerepet tölthet be.
For sometime, climate change has been a major topic for meteorologists and environmentalists alike, but has now become one of the most important social, economic and political question. This change can be called a "social climate change".Therefore, it is understandable that practically all professionals, including physicians and sociologists, are already addressing this question. In Hungary, between October 2018 and December 2019, the role of climate change in the life of society changed, bringing a new phase of'social climate change' in Hungary
- …