593 research outputs found
Dating of Old Lime Based Mixtures with the "Pure Lime Lumps" Technique
A number of studies carried out over the last forty years describe the application of radiocarbon dating of lime mixtures such as mortars, plasters and renders. Despite the fact that this method is very simple in principle, several studies have highlighted various practical challenges and factors that must be considered. These arise mainly from the contamination of samples with carbonaceous substances such as incompletely burnt limestone and aggregates of fossil origin including limestone sand.
However, recently studies have shown that accurate sample processing allow a significant reduction of these error sources and moreover adoption of a special sampling procedure based on the careful selection of lumps of incompletely mixed lime, provides an interesting alternative that avoids problems associated with contamination. The founding principle underlying this technique is the use of the pure lime lumps. These are thought to originate from imperfect mixing and are most prevalent in mortars, renders and plasters predating mechanical mixing. Previous sampling methods for radiocarbon dating did not discriminate between pure and contaminated lime lumps. As pure lumps contain the same lime as that used in other parts of the mixtures but importantly are free of contaminants such as sand grains or under burned pieces of limestone, they can dramatically reduce the errors in the radiocarbon dating
Remarks on the KLS conjecture and Hardy-type inequalities
We generalize the classical Hardy and Faber-Krahn inequalities to arbitrary
functions on a convex body , not necessarily
vanishing on the boundary . This reduces the study of the
Neumann Poincar\'e constant on to that of the cone and Lebesgue
measures on ; these may be bounded via the curvature of
. A second reduction is obtained to the class of harmonic
functions on . We also study the relation between the Poincar\'e
constant of a log-concave measure and its associated K. Ball body
. In particular, we obtain a simple proof of a conjecture of
Kannan--Lov\'asz--Simonovits for unit-balls of , originally due to
Sodin and Lata{\l}a--Wojtaszczyk.Comment: 18 pages. Numbering of propositions, theorems, etc.. as appeared in
final form in GAFA seminar note
Scaling exponent of the maximum growth probability in diffusion-limited aggregation
An early (and influential) scaling relation in the multifractal theory of
Diffusion Limited Aggregation(DLA) is the Turkevich-Scher conjecture that
relates the exponent \alpha_{min} that characterizes the ``hottest'' region of
the harmonic measure and the fractal dimension D of the cluster, i.e.
D=1+\alpha_{min}. Due to lack of accurate direct measurements of both D and
\alpha_{min} this conjecture could never be put to serious test. Using the
method of iterated conformal maps D was recently determined as D=1.713+-0.003.
In this Letter we determine \alpha_{min} accurately, with the result
\alpha_{min}=0.665+-0.004. We thus conclude that the Turkevich-Scher conjecture
is incorrect for DLA.Comment: 4 pages, 5 figure
The spread of epidemic disease on networks
The study of social networks, and in particular the spread of disease on
networks, has attracted considerable recent attention in the physics community.
In this paper, we show that a large class of standard epidemiological models,
the so-called susceptible/infective/removed (SIR) models can be solved exactly
on a wide variety of networks. In addition to the standard but unrealistic case
of fixed infectiveness time and fixed and uncorrelated probability of
transmission between all pairs of individuals, we solve cases in which times
and probabilities are non-uniform and correlated. We also consider one simple
case of an epidemic in a structured population, that of a sexually transmitted
disease in a population divided into men and women. We confirm the correctness
of our exact solutions with numerical simulations of SIR epidemics on networks.Comment: 12 pages, 3 figure
Transition Form Factors between Pseudoscalar and Vector Mesons in Light-Front Dynamics
We study the transition form factors between pseudoscalar and vector mesons
using a covariant fermion field theory model in dimensions. Performing
the light-front calculation in the frame in parallel with the
manifestly covariant calculation, we note that the suspected nonvanishing
zero-mode contribution to the light-front current does not exist in our
analysis of transition form factors. We also perform the light-front
calculation in a purely longitudinal frame and confirm that the form
factors obtained directly from the timelike region are identical to the ones
obtained by the analytic continuation from the spacelike region. Our results
for the decay process satisfy the constraints on the
heavy-to-heavy semileptonic decays imposed by the flavor independence in the
heavy quark limit.Comment: 20 pages, 14 figure
A Biased Review of Sociophysics
Various aspects of recent sociophysics research are shortly reviewed:
Schelling model as an example for lack of interdisciplinary cooperation,
opinion dynamics, combat, and citation statistics as an example for strong
interdisciplinarity.Comment: 16 pages for J. Stat. Phys. including 2 figures and numerous
reference
Hadronic Mass Spectrum Analysis of D+ into K- pi+ mu+ nu Decay and Measurement of the K*(892)^0 Mass and Width
We present a Kpi mass spectrum analysis of the four-body semileptonic charm
decay D+ into K- pi+ mu+ nu in the range of 0.65 GeV < mKpi < 1.5 GeV. We
observe a non-resonant contribution of 5.30 +- 0.74 +0.99 -0.51 % with respect
to the total D+ into K- pi+ mu+ nu decay. For the K*(892)^0 resonance, we
obtain a mass of 895.41 +- 0.32 +0.35 -0.36 MeV, a width of 47.79 +- 0.86 +1.3
-1.1 MeV, and a Blatt-Weisskopf damping factor parameter of 3.96 +- 0.54 +0.72
-0.90 GeV^(-1). We also report 90 % CL upper limits of 4 % and 0.64 % for the
branching ratios of D+ into K*(1680)^0 mu+ nu with respect to D+ into K- pi+
mu+ nu and D+ into K*(1430)^0 mu+ nu with respect to D+ into K- pi+ mu+ nu,
respectively.Comment: 14 page
Measurement of the Ratio of the Vector to Pseudoscalar Charm Semileptonic Decay Rate \Gamma(D+ > ANTI-K*0 mu+ nu)/\Gamma(D+ > ANTI-K0 mu+ nu)
Using a high statistics sample of photo-produced charm particles from the
FOCUS experiment at Fermilab, we report on the measurement of the ratio of
semileptonic rates \Gamma(D+ > ANTI-K pi mu+ nu)/\Gamma(D+ > ANTI-K0 mu+ nu)=
0.625 +/- 0.045 +/- 0.034. Allowing for the K pi S-wave interference measured
previously by FOCUS, we extract the vector to pseudoscalar ratio \Gamma(D+ >
ANTI-K*0 mu+ nu)/\Gamma(D+ > ANTI-K0 mu+ nu)= 0.594 +/- 0.043 +/- 0.033 and the
ratio \Gamma(D+ > ANTI-K0 mu+ nu)/\Gamma(D+ > K- pi+ pi+)= 1.019 +/- 0.076 +/-
0.065. Our results show a lower ratio for \Gamma(D > K* \ell nu})/\Gamma(D > K
\ell nu) than has been reported recently and indicate the current world average
branching fractions for the decays D+ >ANTI-K0(mu+, e+) nu are low. Using the
PDG world average for B(D+ > K- pi+ pi+) we extract B(D+ > ANIT-K0 mu+
nu)=(9.27 +/- 0.69 +/- 0.59 +/- 0.61)%.Comment: 15 pages, 1 figur
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