Fourth order perturbative expansion for the Casimir energy with a slightly deformed plate

We apply a perturbative approach to evaluate the Casimir energy for a massless real scalar field in 3+1 dimensions, subject to Dirichlet boundary conditions on two surfaces. One of the surfaces is assumed to be flat, while the other corresponds to a small deformation, described by a single function $\eta$, of a flat mirror. The perturbative expansion is carried out up to the fourth order in the deformation $\eta$, and the results are applied to the calculation of the Casimir energy for corrugated mirrors in front of a plane. We also reconsider the proximity force approximation within the context of this expansion.Comment: 10 pages, 3 figures. Version to appear in Phys. Rev.

Flexible generation of correlated photon pairs in different frequency ranges

The feasibility to generate correlated photon pairs at variable frequencies is investigated. For this purpose, we consider the interaction of an off-resonant laser field with a two-level system possessing broken inversion symmetry. We show that the system generates non-classical photon pairs exhibiting strong intensity-intensity correlations. The intensity of the applied laser tunes the degree of correlation while the detuning controls the frequency of one of the photons which can be in the THz-domain. Furthermore, we observe the violation of a Cauchy-Schwarz inequality characterizing these photons.Comment: 5 pages, 4 figure

Noninvasive Urinary Monitoring of Progression in IgA Nephropathy.

Standard methods for detecting and monitoring of IgA nephropathy (IgAN) have conventionally required kidney biopsies or suffer from poor sensitivity and specificity. The Kidney Injury Test (KIT) Assay of urinary biomarkers has previously been shown to distinguish between various kidney pathologies, including chronic kidney disease, nephrolithiasis, and transplant rejection. This validation study uses the KIT Assay to investigate the clinical utility of the non-invasive detection of IgAN and predicting the progression of renal damage over time. The study design benefits from longitudinally collected urine samples from an investigator-initiated, multicenter, prospective study, evaluating the efficacy of corticosteroids versus Rituximab for preventing progressive IgAN. A total of 131 urine samples were processed for this study; 64 urine samples were collected from 34 IgAN patients, and urine samples from 64 demographically matched healthy controls were also collected; multiple urinary biomarkers consisting of cell-free DNA, methylated cell-free DNA, DMAIMO, MAMIMO, total protein, clusterin, creatinine, and CXCL10 were measured by the microwell-based KIT Assay. An IgA risk score (KIT-IgA) was significantly higher in IgAN patients as compared to healthy control (87.76 vs. 14.03, p < 0.0001) and performed better than proteinuria in discriminating between the two groups. The KIT Assay biomarkers, measured on a spot random urine sample at study entry could distinguish patients likely to have progressive renal dysfunction a year later. These data support the pursuit of larger prospective studies to evaluate the predictive performance of the KIT-IgA score in both screening for non-invasive diagnosis of IgAN, and for predicting risk of progressive renal disease from IgA and utilizing the KIT score for potentially evaluating the efficacy of IgAN-targeted therapies

Selective and Efficient Quantum Process Tomography

In this paper we describe in detail and generalize a method for quantum process tomography that was presented in [A. Bendersky, F. Pastawski, J. P. Paz, Physical Review Letters 100, 190403 (2008)]. The method enables the efficient estimation of any element of the $\chi$--matrix of a quantum process. Such elements are estimated as averages over experimental outcomes with a precision that is fixed by the number of repetitions of the experiment. Resources required to implement it scale polynomically with the number of qubits of the system. The estimation of all diagonal elements of the $\chi$--matrix can be efficiently done without any ancillary qubits. In turn, the estimation of all the off-diagonal elements requires an extra clean qubit. The key ideas of the method, that is based on efficient estimation by random sampling over a set of states forming a 2--design, are described in detail. Efficient methods for preparing and detecting such states are explicitly shown.Comment: 9 pages, 5 figure

Incidental finding of lymphoma after septoplasty.

IntroductionSeptoplasty, or surgical correction of the deviated septum, is an elective, routinely performed rhinologic procedure to address nasal airway obstruction. In many cases, resected septal cartilage and bone fragments are sent for pathologic review, although there is no consensus on this practice. We reported two cases of incidentally diagnosed lymphoma after elective septoplasty and discussed clinical presentation, diagnosis, and management.MethodsRetrospective chart review of two patients who underwent septoplasty at a tertiary academic medical center and found to have incidental lymphoma based on histopathology.ResultsTwo patients who underwent septoplasty had an incidental diagnosis of lymphoma on pathologic analysis. One patient was noted to have an S-shaped septal deviation that produced bilateral nasal obstruction. She underwent a difficult septoplasty, in which the mucoperichondrial flap was firmly adherent to the underlying septum and bone. Final pathology demonstrated diffuse large B-cell lymphoma. She was treated with chemoradiation and remained free of disease at 59 months. The other patient had a history of nasal trauma, which produced left septal deviation. He underwent an uncomplicated septoplasty, with pathology that demonstrated low-grade B-cell lymphoma. Because there was no evidence of active disease, the decision was made to not treat and to observe the patient clinically.ConclusionsThis is the first reported series of septal lymphoma incidentally diagnosed on routine septoplasty. Although histopathologic review of specimens from routine nasal and sinus surgery is not routinely performed, this report highlighted the importance of this process, on a case-by-case basis, in detecting unexpected malignancies that otherwise were clinically silent

The quantum one-time pad in the presence of an eavesdropper

A classical one-time pad allows two parties to send private messages over a public classical channel -- an eavesdropper who intercepts the communication learns nothing about the message. A quantum one-time pad is a shared quantum state which allows two parties to send private messages or private quantum states over a public quantum channel. If the eavesdropper intercepts the quantum communication she learns nothing about the message. In the classical case, a one-time pad can be created using shared and partially private correlations. Here we consider the quantum case in the presence of an eavesdropper, and find the single letter formula for the rate at which the two parties can send messages using a quantum one-time pad

Derivative expansion of the electromagnetic Casimir energy for two thin mirrors

We extend our previous work on a derivative expansion for the Casimir energy, to the case of the electromagnetic field coupled to two thin, imperfect mirrors. The latter are described by means of vacuum polarization tensors localized on the mirrors. We apply the results so obtained to compute the first correction to the proximity force approximation to the static Casimir effect.Comment: Version to appear in Phys. Rev.

Spinning test particles and clock effect in Kerr spacetime

We study the motion of spinning test particles in Kerr spacetime using the Mathisson-Papapetrou equations; we impose different supplementary conditions among the well known Corinaldesi-Papapetrou, Pirani and Tulczyjew's and analyze their physical implications in order to decide which is the most natural to use. We find that if the particle's center of mass world line, namely the one chosen for the multipole reduction, is a spatially circular orbit (sustained by the tidal forces due to the spin) then the generalized momentum $P$ of the test particle is also tangent to a spatially circular orbit intersecting the center of mass line at a point. There exists one such orbit for each point of the center of mass line where they intersect; although fictitious, these orbits are essential to define the properties of the spinning particle along its physical motion. In the small spin limit, the particle's orbit is almost a geodesic and the difference of its angular velocity with respect to the geodesic value can be of arbitrary sign, corresponding to the spin-up and spin-down possible alignment along the z-axis. We also find that the choice of the supplementary conditions leads to clock effects of substantially different magnitude. In fact, for co-rotating and counter-rotating particles having the same spin magnitude and orientation, the gravitomagnetic clock effect induced by the background metric can be magnified or inhibited and even suppressed by the contribution of the individual particle's spin. Quite surprisingly this contribution can be itself made vanishing leading to a clock effect undistiguishable from that of non spinning particles. The results of our analysis can be observationally tested.Comment: IOP macros, eps figures n. 12, to appear on Classical and Quantum Gravity, 200