Magnetic trapping of neutral particles: Classical and Quantum-mechanical study of a Ioffe-Pritchard type trap

Recently, we developed a method for calculating the lifetime of a particle inside a magnetic trap with respect to spin flips, as a first step in our efforts to understand the quantum-mechanics of magnetic traps. The 1D toy model that was used in this study was physically unrealistic because the magnetic field was not curl-free. Here, we study, both classically and quantum-mechanically, the problem of a neutral particle with spin S, mass m and magnetic moment mu, moving in 3D in an inhomogeneous magnetic field corresponding to traps of the Ioffe-Pritchard, `clover-leaf' and `baseball' type. Defining by omega_p, omega_z and omega_r the precessional, the axial and the lateral vibrational frequencies, respectively, of the particle in the adiabatic potential, we find classically the region in the $(\omega_{r}% (omega_r -- omega_z) plane where the particle is trapped. Quantum-mechanically, we study the problem of a spin-one particle in the same field. Treating omega_r / omega_p and omega_z / omega_p as small parameters for the perturbation from the adiabatic Hamiltonian, we derive a closed-form expression for the transition rate 1/T_{esc} of the particle from its trapped ground-state. We find that in the extreme cases, the expression for 1/T_{esc} is dominated by the largest of the two frequencies omega_r and omega_z.Comment: 25 pages + 1 EPS figur

Expected Behavior of Quantum Thermodynamic Machines with Prior Information

We estimate the expected behavior of a quantum model of heat engine when we have incomplete information about external macroscopic parameters, like magnetic field controlling the intrinsic energy scales of the working medium. We explicitly derive the prior probability distribution for these unknown parameters, $a_i, (i=1,2)$. Based on a few simple assumptions, the prior is found to be of the form $\Pi(a_i) \propto 1/a_i$. By calculating the expected values of various physical quantities related to this engine, we find that the expected behavior of the quantum model exhibits thermodynamic-like features. This leads us to a surprising proposal that incomplete information quantified as appropriate prior distribution can lead us to expect classical thermodynamic behavior in quantum models.Comment: Revtex, 13 pages, 3 figures, revised version, new results added, accepted for Phys. Rev.

Studying the Nature of Dark Energy with Galaxy Clusters

We report on the status of our effort to constrain the nature of dark energy through the evolution of the cluster mass function. Chandra temperature profiles for 31 clusters from a local cluster sample are shown. The X-ray appearance of the proto supermassive binary black hole at the center of the cluster Abell 400 is described. Preliminary weak lensing results obtained with Megacam@MMT for a redshift z=0.5 cluster from a distant cluster sample are given.Comment: 5 pages, to appear in: Aschenbach, B., Burwitz, V., Hasinger, G., Leibundgut, B. (eds.), Relativistic Astrophysics and Cosmology - Einstein's Legacy. ESO Astrophysics Symposia, Springer Verlag, Berlin, German

Direct amplification and differentiation of pathogenic and nonpathogenic Entamoeba histolytica DNA from stool specimens

Discrimination of pathogenic and nonpathogenic Entamoeba histolytica is of great clinical importance. A simple and rapid DNA extraction method that can be used directly with stool specimens was developed without the need for prior cultivation of the parasites. The entire protocol can be performed at room temperature in a 1.5-ml microcentrifuge tube format. There is no DNA precipitation step. The subsequent nested polymerase chain reaction consists of an initial E. histolytica-specific amplification, followed by two separate amplifications using two primer pairs specific for pathogenic and nonpathogenic E. histolytica, respectively. Amplification products can be verified by restriction endonuclease digests. There is no need for hybridizations or the use of radionucleotides. One trophozoite per milligram of stool sample could be detected and differentiated in a 0.1-g specimen

Estimating the effect of joint interventions from observational data in sparse high-dimensional settings

We consider the estimation of joint causal effects from observational data. In particular, we propose new methods to estimate the effect of multiple simultaneous interventions (e.g., multiple gene knockouts), under the assumption that the observational data come from an unknown linear structural equation model with independent errors. We derive asymptotic variances of our estimators when the underlying causal structure is partly known, as well as high-dimensional consistency when the causal structure is fully unknown and the joint distribution is multivariate Gaussian. We also propose a generalization of our methodology to the class of nonparanormal distributions. We evaluate the estimators in simulation studies and also illustrate them on data from the DREAM4 challenge.Comment: 30 pages, 3 figures, 45 pages supplemen