297 research outputs found
Logarithmic Corrections to Scaling in the --Model
We study the distribution of partition function zeroes for the --model in
two dimensions. In particular we find the scaling behaviour of the end of the
distribution of zeroes in the complex external magnetic field plane in the
thermodynamic limit (the Yang--Lee edge) and the form for the density of these
zeroes. Assuming that finite--size scaling holds, we show that there have to
exist logarithmic corrections to the leading scaling behaviour of thermodynamic
quantities in this model. These logarithmic corrections are also manifest in
the finite--size scaling formulae and we identify them numerically. The method
presented here can be used to check the compatibility of scaling behaviour of
odd and even thermodynamic functions in other models too.Comment: 3 pages, latex, 2 figure
Implications of neoadjuvant therapy in human epidermal growth factor receptor 2–positive breast cancer
Breast cancer outcomes have markedly improved in great part because of advances in therapy. These improved outcomes, however, have been accompanied by greater financial costs, toxicities, and overtreatment of a substantial number of patients. We must now focus on studies that leverage our accumulated knowledge and use a more individualized approach for the locoregional and systemic management of this disease. De-escalation trials can be harder to perform as a result of the complexities of noninferiority designs, difficulty in funding them, and human nature. Behavioral economists find that people experience negative feelings about losses more strongly than positive feelings about gains of similar size. This makes it harder to conduct trials that are designed to treat breast cancer precisely rather than comprehensively, including studies that aim to de-escalate standard therapy
Logarithmic Corrections to Scaling in the Two Dimensional --Model
By expressing thermodynamic functions in terms of the edge and density of
Lee--Yang zeroes, we relate the scaling behaviour of the specific heat to that
of the zero field magnetic susceptibility in the thermodynamic limit of the
--model in two dimensions. Assuming that finite--size scaling holds, we
show that the conventional Kosterlitz--Thouless scaling predictions for these
thermodynamic functions are not mutually compatable unless they are modified by
multiplicative logarithmic corrections. We identify these logarithmic
corrections analytically in the case of the specific heat and numerically in
the case of the susceptibility. The techniques presented here are general and
can be used to check the compatibility of scaling behaviour of odd and even
thermodynamic functions in other models too.Comment: 11 pages, latex, 4 figure
No Evidence Supporting Flare Driven High-Frequency Global Oscillations
The underlying physics that generates the excitations in the global
low-frequency, < 5.3 mHz, solar acoustic power spectrum is a well known process
that is attributed to solar convection; However, a definitive explanation as to
what causes excitations in the high-frequency regime, > 5.3 mHz, has yet to be
found. Karoff and Kjeldsen (Astrophys. J. 678, 73-76, 2008) concluded that
there is a correlation between solar flares and the global high-frequency solar
acoustic waves. We have used the Global Oscillations Network Group (GONG)
helioseismic data in an attempt to verify Karoff and Kjeldsen (2008) results as
well as compare the post-flare acoustic power spectrum to the pre-flare
acoustic power spectrum for 31 solar flares. Among the 31 flares analyzed, we
observe that a decrease in acoustic power after the solar flare is just as
likely as an increase. Furthermore, while we do observe variations in acoustic
power that are most likely associated with the usual p-modes associated with
solar convection, these variations do not show any significant temporal
association with flares. We find no evidence that consistently supports flare
driven high-frequency waves.Comment: 20 pages, 9 figures, Accepted for publication in Solar Physic
Disposition of docosahexaenoic acid-paclitaxel, a novel taxane, in blood: in vitro and clinical pharmacokinetic studies
PURPOSE: Docosahexaenoic acid-paclitaxel is as an inert prodrug composed
of the natural fatty acid DHA covalently linked to the C2'-position of
paclitaxel (M. O. Bradley et al., Clin. Cancer Res., 7: 3229-3238, 2001).
Here, we examined the role of protein binding as a determinant of the
pharmacokinetic behavior of DHA-paclitaxel. EXPERIMENTAL DESIGN: The blood
distribution of DHA-paclitaxel was studied in vitro using equilibrium
dialysis and in 23 cancer patients receiving the drug as a 2-h i.v.
infusion (dose, 200-1100 mg/m(2)). RESULTS: In vitro, DHA-paclitaxel was
found to bind extensively to human plasma (99.6 +/- 0.057%). The binding
was concentration independent (P = 0.63), indicating a nonspecific,
nonsaturable process. The fraction of unbound paclitaxel increased from
0.052 +/- 0.0018 to 0.055 +/- 0.0036 (relative increase, 6.25%; P = 0.011)
with an increase in DHA-paclitaxel concentration (0-1000 microg/ml),
suggesting weakly competitive drug displacement from protein-binding
sites. The mean (+/- SD) area under the curve of unbound paclitaxel
increased nonlinearly with dose from 0.089 +/- 0.029 microg.h/ml (at 660
mg/m(2)) to 0.624 +/- 0.216 microg.h/ml (at 1100 mg/m(2)), and was
associated with the dose-limiting neutropenia in a maximum-effect model
(R(2) = 0.624). A comparative analysis indicates that exposure to
Cremophor EL and unbound paclitaxel after DHA-paclitaxel (at 1100 mg/m(2))
is similar to that achieved with paclitaxel on clinically relevant dose
schedules. CONCLUSIONS: Extensive binding to plasma proteins may explain,
in part, the unique pharmacokinetic profile of DHA-paclitaxel described
previously with a small volume of distribution ( approximately 4 liters)
and slow systemic clearance ( approximately 0.11 liters/h)
The Kosterlitz-Thouless Universality Class
We examine the Kosterlitz-Thouless universality class and show that essential
scaling at this type of phase transition is not self-consistent unless
multiplicative logarithmic corrections are included. In the case of specific
heat these logarithmic corrections are identified analytically. To identify
those corresponding to the susceptibility we set up a numerical method
involving the finite-size scaling of Lee-Yang zeroes. We also study the density
of zeroes and introduce a new concept called index scaling. We apply the method
to the XY-model and the closely related step model in two dimensions. The
critical parameters (including logarithmic corrections) of the step model are
compatable with those of the XY-model indicating that both models belong to the
same universality class. This result then raises questions over how a vortex
binding scenario can be the driving mechanism for the phase transition.
Furthermore, the logarithmic corrections identified numerically by our methods
of fitting are not in agreement with the renormalization group predictions of
Kosterlitz and Thouless.Comment: 36 pages (latex), plus 10 figures (postscript). This version to
appear in Nuclear Physics
Emergence of Skyrme crystal in Gross-Neveu and 't Hooft models at finite density
We study two-dimensional, large field theoretic models (Gross-Neveu
model, 't Hooft model) at finite baryon density near the chiral limit. The same
mechanism which leads to massless baryons in these models induces a breakdown
of translational invariance at any finite density. In the chiral limit baryonic
matter is characterized by a spatially varying chiral angle with a wave number
depending only on the density. For small bare quark masses a sine-Gordon kink
chain is obtained which may be regarded as simplest realization of the Skyrme
crystal for nuclear matter. Characteristic differences between confining and
non-confining models are pointed out.Comment: 27 pages, 11 figures, added reference, corrected sig
A statistical correlation of sunquakes based on their seismic and white-light emission
Several mechanisms have been proposed to explain the transient seismic emission, i.e. “sunquakes,” from some solar flares. Some theories associate high-energy electrons and/or white-light emission with sunquakes. High-energy charged particles and their subsequent heating of the photosphere and/or chromosphere could induce acoustic waves in the solar interior. We carried out a correlative study of solar flares with emission in hard X-rays, enhanced continuum emission at 6173 Å, and transient seismic emission. We selected those flares observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) with a considerable flux above 50 keV between 1 January 2010 and 26 June 2014. We then used data from the Helioseismic and Magnetic Imager onboard the Solar Dynamic Observatory to search for excess visible-continuum emission and new sunquakes not previously reported. We found a total of 18 sunquakes out of 75 flares investigated. All of the sunquakes were associated with an enhancement of the visible continuum during the flare. Finally, we calculated a coefficient of correlation for a set of dichotomic variables related to these observations. We found a strong correlation between two of the standard helioseismic detection techniques, and between sunquakes and visible-continuum enhancements. We discuss the phenomenological connectivity between these physical quantities and the observational difficulties of detecting seismic signals and excess continuum radiation
On mappings preserving the sharp and star orders
The present paper is devoted to the study of linear maps preserving certain relations, such as the sharp partial order and the star partial order in semisimple Banach algebras and C*-algebras.The first author is partially supported by the Spanish Ministry of Science and Innovation, D.G.I. project no.
MTM2011-23843, and Junta de Andaluc´ıa grant FQM375. The second author is also supported by a Plan Propio de Investigaci´on grant from University of Almer´ıa, and Junta de Andaluc´ıa grant FQM 3737. The third author is partially supported by FEDER Funds through “Programa Operacional Factores de Competitividade – COMPETE” and by Portuguese Funds through FCT - “Funda¸c˜ao para a Ciˆencia e a Tecnologia”, within the project
PEst-OE/MAT/UI0013/2014
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