34,018 research outputs found
Magnetic Properties of Pd_(0.996)Mn_(0.004) Films for High Resolution Thermometry
We have previously reported on the temperature and magnetic field dependence of the magnetic susceptibility of thin Pd_(1−x)Mn_x alloy films. Extensive new measurements on sputtered films show that a commercial quality sputtering process produces a film with the same dependence of Curie temperature on x as previously reported for bulk samples of the same material. These measurements and parameters from the Renormalization Group theory for a Heisenberg ferromagnet, yield an estimate for T_c of 1.16 ± 0.01 K when x − 0.004, consistent with previously reported bulk result
Decoherence of one-dimensional flying qubits due to their cross-talk and imperfections
We study decoherence of propagating spin-1/2 excitations in generic
(non-integrable and/or disordered) spin chains. We find the relevant
decoherence times to be shorter in both the near-critical and diffusive regimes
(if any), which fact might have important implications for the recently
proposed spin chain-based implementations of quantum information processing.Comment: Latex, 5 pages, no figure
Acyclic orientations with path constraints
Many well-known combinatorial optimization problems can be stated over the
set of acyclic orientations of an undirected graph. For example, acyclic
orientations with certain diameter constraints are closely related to the
optimal solutions of the vertex coloring and frequency assignment problems. In
this paper we introduce a linear programming formulation of acyclic
orientations with path constraints, and discuss its use in the solution of the
vertex coloring problem and some versions of the frequency assignment problem.
A study of the polytope associated with the formulation is presented, including
proofs of which constraints of the formulation are facet-defining and the
introduction of new classes of valid inequalities
The Influence of Sodium Fluoride upon the Composition of Tibiae of Rats Partially Recovering from Rickets
McClure (1) has recently called attention to the need for additional information dealing with the localization of fluorine in teeth and bones and with associative factors invoked in its absorption and metabolism. The work of Roholm (2) and Shortt (3) with the human being appeared to support this viewpoint strongly. Roholm (2) found that fluoride may cause either osteomalacia or osteosclerosis and that storage of fluorine in the bodies of female workers in the cryolite industry in Denmark was sometimes sufficiently great that, even after they left the factory, enough fluorine to cause tooth damage was secreted in their milk. Shortt (3) et al. found ostcosclerosis associated with 30 to 45 years residence in a mottled enamel area in India
Comparative Quantizations of (2+1)-Dimensional Gravity
We compare three approaches to the quantization of (2+1)-dimensional gravity
with a negative cosmological constant: reduced phase space quantization with
the York time slicing, quantization of the algebra of holonomies, and
quantization of the space of classical solutions. The relationships among these
quantum theories allow us to define and interpret time-dependent operators in
the ``frozen time'' holonomy formulation.Comment: 24 pages, LaTeX, no figure
The Effects of Fluorides on the Teeth
Mention was made, in the previous paper, of the fact that mottled enamel of the teeth results from the presence of fluorine in the water supply. The water of the city of Ankeny and surrounding territory may have a fluorine concentration to exceed eight or ten parts per million of water; mottled enamel is very prevalent in that area. Work by Smith (1) of the University of Arizona indicates that mottled enamel may result when the concentration of fluorine is as low as 0.8 to 0.9 part per million of water. The work of Schulz and Lamb (2) and McCollum, Simmonds, Becker, and Bunting (3) has demonstrated that sodium fluoride when fed to rats will produce abnormalities of the teeth of these animals similar to that generally known as mottled enamel in human beings. The work reported in this paper had as its object to ascertain if other inorganic fluorides will produce mottled enamel and also to determine if mottled enamel can be produced by organic fluorides. Furthermore, it was deemed advisable to ascertain if the administration of alum (aluminum sulphate) along with sodium fluoride would prevent the development of mottled enamel
Time-domain Brillouin Scattering as a Local Temperature Probe in Liquids
We present results of time-domain Brillouin scattering (TDBS) to determine
the local temperature of liquids in contact to an optical transducer. TDBS is
based on an ultrafast pump-probe technique to determine the light scattering
frequency shift caused by the propagation of coherent acoustic waves in a
sample. Since the temperature influences the Brillouin scattering frequency
shift, the TDBS signal probes the local temperature of the liquid. Results for
the extracted Brillouin scattering frequencies recorded at different liquid
temperatures and at different laser powers - i.e. different steady state
background temperatures- are shown to demonstrate the usefulness of TDBS as a
temperature probe. This TDBS experimental scheme is a first step towards the
investigation of ultrathin liquids measured by GHz ultrasonic probing.Comment: arXiv admin note: substantial text overlap with arXiv:1702.0107
Topological low-temperature limit of Z(2) spin-gauge theory in three dimensions
We study Z(2) lattice gauge theory on triangulations of a compact 3-manifold.
We reformulate the theory algebraically, describing it in terms of the
structure constants of a bidimensional vector space H equipped with algebra and
coalgebra structures, and prove that in the low-temperature limit H reduces to
a Hopf Algebra, in which case the theory becomes equivalent to a topological
field theory. The degeneracy of the ground state is shown to be a topological
invariant. This fact is used to compute the zeroth- and first-order terms in
the low-temperature expansion of Z for arbitrary triangulations. In finite
temperatures, the algebraic reformulation gives rise to new duality relations
among classical spin models, related to changes of basis of H.Comment: 10 pages, no figure
Concise theory of chiral lipid membranes
A theory of chiral lipid membranes is proposed on the basis of a concise free
energy density which includes the contributions of the bending and the surface
tension of membranes, as well as the chirality and orientational variation of
tilting molecules. This theory is consistent with the previous experiments
[J.M. Schnur \textit{et al.}, Science \textbf{264}, 945 (1994); M.S. Spector
\textit{et al.}, Langmuir \textbf{14}, 3493 (1998); Y. Zhao, \textit{et al.},
Proc. Natl. Acad. Sci. USA \textbf{102}, 7438 (2005)] on self-assembled chiral
lipid membranes of DCPC. A torus with the ratio between its two
generated radii larger than is predicted from the Euler-Lagrange
equations. It is found that tubules with helically modulated tilting state are
not admitted by the Euler-Lagrange equations, and that they are less
energetically favorable than helical ripples in tubules. The pitch angles of
helical ripples are theoretically estimated to be about 0 and
35, which are close to the most frequent values 5 and
28 observed in the experiment [N. Mahajan \textit{et al.}, Langmuir
\textbf{22}, 1973 (2006)]. Additionally, the present theory can explain twisted
ribbons of achiral cationic amphiphiles interacting with chiral tartrate
counterions. The ratio between the width and pitch of twisted ribbons is
predicted to be proportional to the relative concentration difference of left-
and right-handed enantiomers in the low relative concentration difference
region, which is in good agreement with the experiment [R. Oda \textit{et al.},
Nature (London) \textbf{399}, 566 (1999)].Comment: 14 pages, 7 figure
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