Variation of discrete spectra for non-selfadjoint perturbations of selfadjoint operators

Let B=A+K where A is a bounded selfadjoint operator and K is an element of the von Neumann-Schatten ideal S_p with p>1. Let {\lambda_n} denote an enumeration of the discrete spectrum of B. We show that \sum_n \dist(\lambda_n, \sigma(A))^p is bounded from above by a constant multiple of |K|_p^p. We also derive a unitary analog of this estimate and apply it to obtain new estimates on zero-sets of Cauchy transforms.Comment: Differences to previous version: Extended Introduction, new Section 5, additional references. To appear in Int. Eq. Op. Theor

Radiative transitions involving the (2p2)(3 Pe) metastable autodetaching of H(-)

The absorption coefficient for the free-bound transition H (ls) + e(-)+ h omega yields H(-)(2 sq p,(3)P(e)) is calculated (together with the differential emission rate for the inverse process) using ls - 2s - 2p close coupling continuum wave functions and a Hylleraas bound state wave function. A maximum in the absorption and emission spectra is found to occur at a photon wavelength of 1219.5 A, which is 2 A closer to the Lyman alpha line than predicted by the calculations of Drake, and is in closer agreement with the stellar absorption feature identified by Heap and Stecher. The free-bound absorption process appears to be a significant source of continuous ultraviolet opacity

Charateristics of Indian Tubercle Bacilli

As result of the studies undertaken during the last 4 years at the Tuberculosis Chemotherapy Centre, Madras, some characteristics of Indian tubercle bacilli which differ from those of British tubercle bacilli have been observed. These factors relate to their virulence in the guinea-pig, susceptibility to hydrogen peroxide, and drug sensitivity. The Indian and British cultures are, however, closely similar in the majority of their in vitro characteristics. Before proceeding further, it must be emphasized, that the findings reported in this paper apply to cultures obtained from a rather selected group of patients. These patients presented themselves because of symptoms and the vast majority of them were positive on smear examination and had moderately or far advanced disease. Furthermore, all the patients were residents of Madras city

Encapsulation of particles using brittle coatings for subterranean applications

The production of a brittle and moisture-resistant coating for particles, which reduce or break the viscosity of fracturing fluids, was explored.;The viscosity-reducer was ammonium persulfate. Polyurethane and acrylate coatings were investigated. The coated particles were assessed for dissolution in water before and after being subjected to a compression test. Polyurethane-coated particles had a high leach prior to compression and were considered unsuitable. Acrylate coatings gave much better results. The addition of significant quantities of silica in the coat increased significantly its brittleness. The acrylate formed agglomerates during the coating process. These were easier to break than single particles. These agglomerates also gave a low leach rate and large release upon compression.;Agglomerates coated with acrylate and silica provide a novel solution to the opposing constraints of high water resistance and high susceptibility to brittle fracture

Effects of winglet on transonic flutter characteristics of a cantilevered twin-engine-transport wing model

A transonic model and a low-speed model were flutter tested in the Langley Transonic Dynamics Tunnel at Mach numbers up to 0.90. Transonic flutter boundaries were measured for 10 different model configurations, which included variations in wing fuel, nacelle pylon stiffness, and wingtip configuration. The winglet effects were evaluated by testing the transonic model, having a specific wing fuel and nacelle pylon stiffness, with each of three wingtips, a nonimal tip, a winglet, and a nominal tip ballasted to simulate the winglet mass. The addition of the winglet substantially reduced the flutter speed of the wing at transonic Mach numbers. The winglet effect was configuration-dependent and was primarily due to winglet aerodynamics rather than mass. Flutter analyses using modified strip-theory aerodynamics (experimentally weighted) correlated reasonably well with test results. The four transonic flutter mechanisms predicted by analysis were obtained experimentally. The analysis satisfactorily predicted the mass-density-ratio effects on subsonic flutter obtained using the low-speed model. Additional analyses were made to determine the flutter sensitivity to several parameters at transonic speeds

Perfect quantum transport in arbitrary spin networks

Spin chains have been proposed as wires to transport information between distributed registers in a quantum information processor. Unfortunately, the challenges in manufacturing linear chains with engineered couplings has hindered experimental implementations. Here we present strategies to achieve perfect quantum information transport in arbitrary spin networks. Our proposal is based on the weak coupling limit for pure state transport, where information is transferred between two end-spins that are only weakly coupled to the rest of the network. This regime allows disregarding the complex, internal dynamics of the bulk network and relying on virtual transitions or on the coupling to a single bulk eigenmode. We further introduce control methods capable of tuning the transport process and achieve perfect fidelity with limited resources, involving only manipulation of the end-qubits. These strategies could be thus applied not only to engineered systems with relaxed fabrication precision, but also to naturally occurring networks; specifically, we discuss the practical implementation of quantum state transfer between two separated nitrogen vacancy (NV) centers through a network of nitrogen substitutional impurities.Comment: 5+7 page

Quantum correlations and least disturbing local measurements

We examine the evaluation of the minimum information loss due to an unread local measurement in mixed states of bipartite systems, for a general entropic form. Such quantity provides a measure of quantum correlations, reducing for pure states to the generalized entanglement entropy, while in the case of mixed states it vanishes just for classically correlated states with respect to the measured system, as the quantum discord. General stationary conditions are provided, together with their explicit form for general two-qubit states. Closed expressions for the minimum information loss as measured by quadratic and cubic entropies are also derived for general states of two-qubit systems. As application, we analyze the case of states with maximally mixed marginals, where a general evaluation is provided, as well as X states and the mixture of two aligned states.Comment: 10 pages, 3 figure

Robustness of Device Independent Dimension Witnesses

Device independent dimension witnesses provide a lower bound on the dimensionality of classical and quantum systems in a "black box" scenario where only correlations between preparations, measurements and outcomes are considered. We address the problem of the robustness of dimension witnesses, namely that to witness the dimension of a system or to discriminate between its quantum or classical nature, even in the presence of loss. We consider the case when shared randomness is allowed between preparations and measurements and we provide a threshold in the detection efficiency such that dimension witnessing can still be performed.Comment: 8 pages, 5 figures, published versio

The growth rate of tubercle bacilli from South Indian and British patients

CULTURES of tubercle bacilli from Indian patients have been shown to be, on average, less virulent in the guinea-pig and to have a wider range of virulence than cultures obtained from British patients (Frimodt-Moller, Mathew and Barton, 1956 ; Mitchison et al., 1960 ; Bhatia et al., 1961). In the study of Bhatia et al. (loc. cit.) about one-third of the Indian cultures were as virulent as British cultures, the remainder being less virulent. In these studies the extent of disease in the organs of the guinea-pig was scored at intervals after the intramuscular injection of the organisms. In consequence, the measure of virulence was based upon the rate of development of the lesions and, by inference, the rate of multiplication of the bacilli in the organs. It was, therefore, considered of interest to compare the growth rates in vitro of Indian and British cultures of tubercle bacilli