Drifting diffusion on a circle as continuous limit of a multiurn Ehrenfest model

We study the continuous limit of a multibox Erhenfest urn model proposed before by the authors. The evolution of the resulting continuous system is governed by a differential equation, which describes a diffusion process on a circle with a nonzero drifting velocity. The short time behavior of this diffusion process is obtained directly by solving the equation, while the long time behavior is derived using the Poisson summation formula. They reproduce the previous results in the large $M$ (number of boxes) limit. We also discuss the connection between this diffusion equation and the Schr$\ddot{\rm o}$dinger equation of some quantum mechanical problems.Comment: 4 pages prevtex4 file, 1 eps figur

Probing vortices in 4He nanodroplets

We present static and dynamical properties of linear vortices in 4He droplets obtained from Density Functional calculations. By comparing the adsorption properties of different atomic impurities embedded in pure droplets and in droplets where a quantized vortex has been created, we suggest that Ca atoms should be the dopant of choice to detect vortices by means of spectroscopic experiments.Comment: Typeset using Revtex4, 4 pages and 2 Postscript file

Generating vortex rings in Bose-Einstein condensates in the line-source approximation

We present a numerical method for generating vortex rings in Bose-Einstein condensates confined in axially symmetric traps. The vortex ring is generated using the line-source approximation for the vorticity, i.e., the rotational of the superfluid velocity field is different from zero only on a circumference of given radius located on a plane perpendicular to the symmetry axis and coaxial with it. The particle density is obtained by solving a modified Gross-Pitaevskii equation that incorporates the effect of the velocity field. We discuss the appearance of density profiles, the vortex core structure and the vortex nucleation energy, i.e., the energy difference between vortical and ground-state configurations. This is used to present a qualitative description of the vortex dynamics.Comment: Accepted for publication in Phys. Rev.

Energetics and Possible Formation and Decay Mechanisms of Vortices in Helium Nanodroplets

The energy and angular momentum of both straight and curved vortex states of a helium nanodroplet are examined as a function of droplet size. For droplets in the size range of many experiments, it is found that during the pickup of heavy solutes, a significant fraction of events deposit sufficient energy and angular momentum to form a straight vortex line. Curved vortex lines exist down to nearly zero angular momentum and energy, and thus could in principle form in almost any collision. Further, the coalescence of smaller droplets during the cooling by expansion could also deposit sufficient angular momentum to form vortex lines. Despite their high energy, most vortices are predicted to be stable at the final temperature (0.38 K) of helium nanodroplets due to lack of decay channels that conserve both energy and angular momentum.Comment: 10 pages, 8 figures, RevTex 4, submitted to Phys. Rev.

The Synergistic Effect of SAHA and Parthenolide in MDA-MB231 Breast Cancer Cells

The sesquiterpene lactone Parthenolide (PN) exerted a cytotoxic effect on MDA-MB231 cells, a triple-negative breast cancer (TNBC) cell line, but its effectiveness was scarce when employed at low doses. This represents an obstacle for a therapeutic utilization of PN. In order to overcome this difficulty we associated to PN the suberoylanilide hydroxamic acid (SAHA), an histone deacetylase inhibitor. Our results show that SAHA synergistically sensitized MDA-MB231 cells to the cytotoxic effect of PN. It is noteworthy that treatment with PN alone stimulated the survival pathway Akt/mTOR and the consequent nuclear translocation of Nrf2, while treatment with SAHA alone induced autophagic activity. However, when the cells were treated with SAHA/PN combination, SAHA suppressed PN effect on Akt/mTOR/Nrf2 pathway, while PN reduced the prosurvival autophagic activity of SAHA. In addition SAHA/PN combination induced GSH depletion, fall in Δψm, release of cytochrome c, activation of caspase 3 and apoptosis. Finally we demonstrated that combined treatment maintained both hyperacetylation of histones H3 and H4 induced by SAHA and down-regulation of DNMT1 expression induced by PN. Inhibition of the DNA-binding activity of NF-kB, which is determined by PN, was also observed after combined treatment. In conclusion, combination of PN to SAHA inhibits the cytoprotective responses induced by the single compounds, but does not alter the mechanisms leading to the cytotoxic effects. Taken together our results suggest that this combination could be a candidate for TNBC therapy. J. Cell. Physiol. 230: 1276-1289, 2015

Search for the Flavor-Changing Neutral Current Decay D0→μ+μ−D^0 \to \mu^+\mu^- with the HERA-B Detector

We report on a search for the flavor-changing neutral current decay $D^0 \to \mu^+\mu^-$ using $50 \times 10^6$ events recorded with a dimuon trigger in interactions of 920 GeV protons with nuclei by the HERA-B experiment. We find no evidence for such decays and set a 90% confidence level upper limit on the branching fraction $Br(D^0 \to \mu^+\mu^-) <2.0 \times 10^{-6}$.Comment: 17 pages, 4 figures (of which 1 double), paper to be submitted to Physics Letters

Measurement of the J/Psi Production Cross Section in 920 GeV/c Fixed-Target Proton-Nucleus Interactions

The mid-rapidity (dsigma_(pN)/dy at y=0) and total sigma_(pN) production cross sections of J/Psi mesons are measured in proton-nucleus interactions. Data collected by the HERA-B experiment in interactions of 920 GeV/c protons with carbon, titanium and tungsten targets are used for this analysis. The J/Psi mesons are reconstructed by their decay into lepton pairs. The total production cross section obtained is sigma_(pN)(J/Psi) = 663 +- 74 +- 46 nb/nucleon. In addition, our result is compared with previous measurements

Non-Anatomic Proximal Realignment for Recurrent Patellar Dislocation Does Not Sufficiently Prevent Redislocation

Several operative techniques have been described for recurrent patellar dislocation. Clinical results vary depending on the procedure and indication. The present study aimed to evaluate the clinical outcome of Insall’s proximal realignment for recurrent patellar dislocation at mid-term follow-up. Forty-five patients were reviewed with a mean follow-up period of 49 months after having undergone Insall’s procedure. Outcome measures included reports of redislocations, complications, patient-reported outcome scores (Kujala, Tegner activity scale) and subjective assessment. No statistically significant improvements (p < 0.05) in patient-reported outcome measures were noted. Sixteen patients (35%) had poor to fair results using the Kujala score. Subjective assessment revealed that 12 patients (27%) were dissatisfied with the outcome of their surgery and would not undergo the same procedure. Ten patients (22%) had suffered from redislocation at the latest follow-up. In 4 cases (9%), intra-articular knee hematoma occurred which required arthroscopic intervention. The overall mid-term outcome of the present study shows low patient satisfaction. Non-anatomic realignment for recurrent patellar dislocation does not adequately prevent redislocation

Ratio of the Isolated Photon Cross Sections at \sqrt{s} = 630 and 1800 GeV

The inclusive cross section for production of isolated photons has been measured in \pbarp collisions at $\sqrt{s} = 630$ GeV with the \D0 detector at the Fermilab Tevatron Collider. The photons span a transverse energy ($E_T$) range from 7-49 GeV and have pseudorapidity $|\eta| < 2.5$. This measurement is combined with to previous \D0 result at $\sqrt{s} = 1800$ GeV to form a ratio of the cross sections. Comparison of next-to-leading order QCD with the measured cross section at 630 GeV and ratio of cross sections show satisfactory agreement in most of the $E_T$ range.Comment: 7 pages. Published in Phys. Rev. Lett. 87, 251805, (2001

Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO