An Inquiry into the Cause of the Increase of Tuberculosis of Swine

The great increase in the number of swine found to be tuberculous presented a problem, the solution of which appeared to be desirable before adequate control measures could be devised or recommended. In the hope that a solution of the problem may be found this station undertook an investigation and attempted by experimental inquiry to determine the infection type of the tuberculosis associated with the animals which constituted the bulk of the retentions. In view of the apparent increased incidence and spread of tuberculosis among poultry in a large hog raising section, of which Nebraska forms a part, the experimental project mentioned was to a large extent so directed as to prove or disprove the hypothesis that avian infection may at least in part be held accountable for the great morbidity rate for tuberculosis among swine and its marked increase during the last fifteen years

The Immunizing Value of Commercial Vaccines and Bacterins Against Hemorrhagic Septicemia

In the course of certain studies having to do with hemorrhagic septicemia, we were particularly struck with the difficulties which we encountered in the immunization of susceptible laboratory animals (rabbits). This difficulty in no small degree excited our curiosity regarding the immunizing value of the considerable number of Hemorrhagic Septicemia bacterins and vaccines which during recent years have become such a prominent article of commerce. In the hope of securing some information relative to the immunizing value of the agents mentioned, we undertook a series of experiments in which the immunity of the bacterin and vaccine injected laboratory animals was definitely tested by subsequent inoculations with B. bipolaris

The Incidence of Avian Tuberculosis in Mammals other than Swine

The recognition of a very widespread and intense distribution of avian tuberculosis on the farms of a wide area of the United States, as well as the involvement of a mammalian species also, brought to the foreground the question whether or not the great prevalence of poultry tuberculosis could be of importance also from a public health point of view. This phase of the problem not only pertains to the people on the farms but likewise is of fundamental importance to the consumers of poultry produce. European authors had already identified the avian tubercle bacillus in human lesions while in this country careless speakers outside the profession of medicine and irresponsible journalists had made more or less sensational statements on the subject. The alleged public health phase of avian tuberculosis was regarded as warrant for an attempt to acquire more definite information on this subject. The importance of the problem arising from the widespread distribution of avian tuberculosis and its demonstrated communicability to at least one mammalian species of economic importance justified an extension of the investigation and hence the Nebraska Agricultural Experiment Station undertook the inquiry, the results of which are set forth in the following account

The Value of Commercial Vaccines and Bacterins Against Fowl Cholera

A great prevalence of the disease known as fowl cholera has naturally stimulated an interest in possible means of prevention and especially in those which may bring about a more or less lasting immunity. Vaccines which were favorably reported by some failed utterly in the hands of others, so that on the whole no substantial advantage has been gained. Vaccines and bacterins are nevertheless constantly urged on poultry owners confronted with disease and the Experiment Station is frequently called upon to give an opinion on their value or to recommend any special preparation. In order to comply with those demands in an intelligent and impartial manner, we have thought it wise to make some experiments with the various preparations offered by the pharmaceutical trade in the hope that this may enable us to recommend all or any preparation for the relief of our poultry raisers

Three-dimensional character of atom-chip-based rf-dressed potentials

We experimentally investigate the properties of radio-frequency-dressed potentials for Bose-Einstein condensates on atom chips. The three-dimensional potential forms a connected pair of parallel waveguides. We show that rf-dressed potentials are robust against the effect of small magnetic-field variations on the trap potential. Long-lived dipole oscillations of condensates induced in the rf-dressed potentials can be tuned to a remarkably low damping rate. We study a beam-splitter for Bose-Einstein condensates and show that a propagating condensate can be dynamically split in two vertically separated parts and guided along two paths. The effect of gravity on the potential can be tuned and compensated for using a rf-field gradient.Comment: 9 pages, 7 figure

Box traps on an atom chip for one-dimensional quantum gases

We present the implementation of tailored trapping potentials for ultracold gases on an atom chip. We realize highly elongated traps with box-like confinement along the long, axial direction combined with conventional harmonic confinement along the two radial directions. The design, fabrication and characterization of the atom chip and the box traps is described. We load ultracold ($\lesssim1 \mu$K) clouds of $^{87}$Rb in a box trap, and demonstrate Bose-gas focusing as a means to characterize these atomic clouds in arbitrarily shaped potentials. Our results show that box-like axial potentials on atom chips are very promising for studies of one-dimensional quantum gases.Comment: 9 pages 4 figure

Spin transport in graphene nanostructures

Graphene is an interesting material for spintronics, showing long spin relaxation lengths even at room temperature. For future spintronic devices it is important to understand the behavior of the spins and the limitations for spin transport in structures where the dimensions are smaller than the spin relaxation length. However, the study of spin injection and transport in graphene nanostructures is highly unexplored. Here we study the spin injection and relaxation in nanostructured graphene with dimensions smaller than the spin relaxation length. For graphene nanoislands, where the edge length to area ratio is much higher than for standard devices, we show that enhanced spin-flip processes at the edges do not seem to play a major role in the spin relaxation. On the other hand, contact induced spin relaxation has a much more dramatic effect for these low dimensional structures. By studying the nonlocal spin transport through a graphene quantum dot we observe that the obtained values for spin relaxation are dominated by the connecting graphene islands and not by the quantum dot itself. Using a simple model we argue that future nonlocal Hanle precession measurements can obtain a more significant value for the spin relaxation time for the quantum dot by using high spin polarization contacts in combination with low tunneling rates

Yang-Yang thermodynamics on an atom chip

We investigate the behavior of a weakly interacting nearly one-dimensional (1D) trapped Bose gas at finite temperature. We perform in situ measurements of spatial density profiles and show that they are very well described by a model based on exact solutions obtained using the Yang-Yang thermodynamic formalism, in a regime where other, approximate theoretical approaches fail. We use Bose-gas focusing [Shvarchuck etal., Phys. Rev. Lett. 89, 270404 (2002)] to probe the axial momentum distribution of the gas, and find good agreement with the in situ results.Comment: extended introduction and conclusions, and minor changes throughout; accepted for publication in Phys. Rev. Let

Thermoluminescence of zircon: a kinetic model

The mineral zircon, ZrSiO4, belongs to a class of promising materials for geochronometry by means of thermoluminescence (TL) dating. The development of a reliable and reproducible method for TL dating with zircon requires detailed knowledge of the processes taking place during exposure to ionizing radiation, long-term storage, annealing at moderate temperatures and heating at a constant rate (TL measurements). To understand these processes one needs a kinetic model of TL. This paper is devoted to the construction of such amodel. The goal is to study the qualitative behaviour of the system and to determine the parameters and processes controlling TL phenomena of zircon. The model considers the following processes: (i) Filling of electron and hole traps at the excitation stage as a function of the dose rate and the dose for both (low dose rate) natural and (high dose rate) laboratory irradiation. (ii) Time dependence of TL fading in samples irradiated under laboratory conditions. (iii) Short time annealing at a given temperature. (iv) Heating of the irradiated sample to simulate TL experiments both after laboratory and natural irradiation. The input parameters of the model, such as the types and concentrations of the TL centres and the energy distributions of the hole and electron traps, were obtained by analysing the experimental data on fading of the TL-emission spectra of samples from different geological locations. Electron paramagnetic resonance (EPR) data were used to establish the nature of the TL centres. Glow curves and 3D TL emission spectra are simulated and compared with the experimental data on time-dependent TL fading. The saturation and annealing behaviour of filled trap concentrations has been considered in the framework of the proposed kinetic model and comparedwith the EPR data associated with the rare-earth ions Tb3+ and Dy3+, which play a crucial role as hole traps and recombination centres. Inaddition, the behaviour of some of the SiOmn− centres has been compared with simulation results.

Dialkyldithiophosphate Acids (HDDPs) as Effective Lubricants of Sol–Gel Titania Coatings in Technical Dry Friction Conditions

The goal of this study was the investigation of the effectiveness of dialkyldithiophosphate acids (HDDPs) films in improving the tribological properties of thin, sol– gel derived titania coatings. Amorphous, anatase, and rutile titania coatings were obtained using sol–gel dip–coating deposition after treatment at 100, 500, and 1,000 C, respectively. Titania coatings were then modified from the liquid phase by HDDPs acids having dodecyl-(C12), tetradecyl-(C14), and hexadecyl-(C16) alkyl chains deposited by dip–coating (DC) and Langmuir–Blodgett (LB) methods. The influence of the deposition procedure, the length of the HDDPs alkyl chain and the type of titania substrate on the surface morphology and tribological properties were studied. It was found, using wetting contact angle measurements, that these modifications of titania coatings decrease the surface free energy and increase its hydrophobicity. The surface topography imaged by Atomic force microscopy (AFM), exhibit island-like or agglomerate features for the DC deposition method, while smooth topographies were observed for LB depositions. Tribological tests were conducted by means of a microtribometer operating in the normal load range 30–100 mN. An enhancement of tribological properties was observed upon modification, as compared to unmodified titania