3,029 research outputs found
Shapes of the Proton
A model proton wave function, constructed using Poincare invariance, and
constrained by recent electromagnetic form factor data, is used to study the
shape of the proton. Spin-dependent quark densities are defined as matrix
elements of density operators in proton states of definite spin-polarization,
and shown to have an infinite variety of non-spherical shapes. For high
momentum quarks with spin parallel to that of the proton, the shape resembles
that of a peanut, but for quarks with anti-parallel spin the shape is that of a
bagel.Comment: 8 pages, 5 figures, to be submitted to Phys. Rev. C This corrects a
few typos and explains some further connections with experiment
Nucleon Generalized Parton Distributions and Holographic Models
Using ideas from Light Front Holography, we discuss the calculation of the
nucleon helicity-independent generalized parton distributions of quarks in the
zero skewness case.Comment: Prepared for LIGHTCONE 2011, 23 - 27 May, 2011, Dalla
Actors that Unify Threads and Events
There is an impedance mismatch between message-passing concurrency and virtual machines, such as the JVM. VMs usually map their threads to heavyweight OS processes. Without a lightweight process abstraction, users are often forced to write parts of concurrent applications in an event-driven style which obscures control flow, and increases the burden on the programmer. In this paper we show how thread-based and event-based programming can be unified under a single actor abstraction. Using advanced abstraction mechanisms of the Scala programming language, we implemented our approach on unmodified JVMs. Our programming model integrates well with the threading model of the underlying VM
Direct neutron capture cross sections of 62Ni in the s-process energy range
Direct neutron capture on 62Ni is calculated in the DWBA and the cross
sections in the energy range relevant for s-process nucleosynthesis are given.
It is confirmed that the thermal value of the capture cross section contains a
subthreshold resonance contribution. Contrary to previous investigations it is
found that the capture at higher energies is dominated by p-waves, thus leading
to a considerably increased cross section at s-process energies and a modified
energy dependence.Comment: 10 pages, 1 figure, corrected typos in Eq. 6 and subsequent paragrap
A quark model analysis of the charge symmetry breaking in nuclear force
In order to investigate the charge symmetry breaking (CSB) in the short range
part of the nuclear force, we calculate the difference of the masses of the
neutron and the proton, , the difference of the scattering
lengths of the p-p and n-n scatterings, , and the difference of the
analyzing power of the proton and the neutron in the n-p scattering, , by a quark model. In the present model the sources of CSB are the
mass difference of the up and down quarks and the electromagnetic interaction.
We investigate how much each of them contributes to , and . It is found that the contribution of CSB of the
short range part in the nuclear force is large enough to explain the observed
, while is rather underestimated.Comment: 26 pages,6 figure
Quark Coulomb Interactions and the Mass Difference of Mirror Nuclei
We study the Okamoto-Nolen-Schiffer (ONS) anomaly in the binding energy of
mirror nuclei at high density by adding a single neutron or proton to a quark
gluon plasma. In this high-density limit we find an anomaly equal to two-thirds
of the Coulomb exchange energy of a proton. This effect is dominated by quark
electromagnetic interactions---rather than by the up-down quark mass
difference. At normal density we calculate the Coulomb energy of neutron matter
using a string-flip quark model. We find a nonzero Coulomb energy because of
the neutron's charged constituents. This effect could make a significant
contribution to the ONS anomaly.Comment: 4 pages, 2 figs. sub. to Phys. Rev. Let
Filtering spin with tunnel-coupled electron wave guides
We show how momentum-resolved tunneling between parallel electron wave guides
can be used to observe and exploit lifting of spin degeneracy due to Rashba
spin-orbit coupling. A device is proposed that achieves spin filtering without
using ferromagnets or the Zeeman effect.Comment: 4 pages, 4 figures, RevTex
A dynamical chiral bag model
We study a dynamical chiral bag model, in which massless fermions are
confined within an impenetrable but movable bag coupled to meson fields. The
self-consistent motion of the bag is obtained by solving the equations of
motion exactly assuming spherical symmetry. When the bag interacts with an
external meson wave we find three different kinds of resonances: {\it
fermionic}, {\it geometric}, and -resonances. We discuss the
phenomenological implications of our results.Comment: Two columns, 11 pages, 9 figures. Submitted to Physical Review
Pharmacokinetics, Tissue Distribution and Therapeutic Effect of Cationic Thermosensitive Liposomal Doxorubicin Upon Mild Hyperthermia
Purpose: To evaluate pharmacokinetic profile, biodistribution and therapeutic effect of cationic thermosensitive liposomes (CTSL) encapsulating doxorubicin (Dox) upon mild hyperthermia (HT). Methods: Non-targeted thermosensitive liposomes (TSL) and CTSL were developed, loaded with Dox and characterized. Blood kinetics and biodistribution of Dox-TSL and Dox-CTSL were followed in B16BL6 tumor bearing mice upon normothermia (NT) or initial hyperthermia conditions. Efficacy study in B16BL6 tumor bearing mice was followed with Dox-TSL or Dox-CTSL upon NT or HT. Efficacy study in LLC tumor bearing mice was performed upon two HT conditions. Intravital microscopy was performed on B16BL6 tumors implanted in dorsal-skin fold window-bearing mice. Results: Targeting did not cause faster blood clearance of CTSL compared to TSL. Highest uptake of liposomes was observed in spleen, kidneys and liver. Applying HT prior to CTSL administration increased drug delivery to the tumor and CTSL delivered ∼1.7 fold higher Dox concentration compared to TSL. Efficacy in B16BL6 murine melanoma showed that HT had a significant effect on CTSL in tumor suppression and prolonged survival. Efficacy in LLC Lewis lung carcinoma tumor model demonstrates that two HT treatments hold promises for a successful treatment option. Conclusion: CTSL have potency to increase drug efficacy in tumors due to their targeted and drug release functions
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