Electrical activity and ionic gradients in cardiac muscle: with special reference to the effects of 2-4-dinitrophenol

This Thesis is divided into three parts. In Part I the electrical activity and intracellular ionic contents of sodium, potassium and chloride in the rat auricle have been investigated, to test a hypothesis advanced by Shanes (l958) to account for the action of 2-4-dinitrophenol on the heart. In Part II some observations on arrhythmias produced by 2- 4- dinitrophenol in the heart have been extended and investigated. In Part III the results of a few polarisation experiments are presented.Since the main body of the work has been done and the Thesis written, additional experiments on the efflux of chloride using Br⁸² as .tracer have been carried out. The results of tnese experiment have been added in the results of Part I

X-ray Pulsars in the Small Magellanic Cloud

XMM-Newton archival data for the Small Magellanic Cloud have been examined for the presence of previously undetected X-ray pulsars. One such pulsar, with a period of 202 s, is detected. Its position is consistent with an early B star in the SMC and we identify it as a high mass X-ray binary (HMXB). In the course of this study we determined the pulse period of the possible AXP CXOU J010043.1-721134 to be 8.0 s, correcting an earlier report (Lamb et al 2002b) of a 5.4 s period for this object. Pulse profiles and spectra for each of these objects are presented as well as for a recently discovered (Haberl & Pietsch 2004) 263 s X-ray pulsar. Properties of an ensemble of 24 optically identified HMXB pulsars from the SMC are investigated. The locations of the pulsars and an additional 22 X-ray pulsars not yet identified as having high mass companions are located predominately in the young (ages $\le 3 \times 10^{7}$ years) star forming regions of the SMC as expected on the basis of binary evolution models. We find no significant difference between the distribution of spin periods for the HMXB pulsars of the SMC compared with that of the Milky Way. For those HMXB pulsars which have Be companions we note an inverse correlation between spin period and maximum X-ray flux density. (This anti-correlation has been previously noted for all X-ray binary pulsars by Stella, White & Rosner 1986). The anti-correlation for the Be binaries may be a reflection of the fact that the spin periods and orbital periods of Be HMXBs are correlated. We note a similar correlation between X-ray luminosity and spin period for the Be HMXB pulsars of the Milky Way and speculate that exploitation of the correlation could serve as a distance indicator.Comment: final version accepted in The Astrophysical Journa

Quasiperiodic oscillations in bright galactic-bulge X-ray sources

Quasiperiodic oscillations with frequencies in the range 5-50 Hz have recently been discovered in X-rays from two bright galactic-bulge sources and Sco X-1. These sources are weakly magnetic neutron stars accreting from disks which the plasma is clumped. The interaction of the magnetosphere with clumps in the inner disk causes oscillations in the X-ray flux with many of the properties observed

Malaria-filaria coinfection in mice makes malarial disease more severe unless filarial infection achieves patency

Coinfections are common in natural populations, and the literature suggests that helminth coinfection readily affects how the immune system manages malaria. For example, type 1–dependent control of malaria parasitemia might be impaired by the type 2 milieu of preexisting helminth infection. Alternatively, immunomodulatory effects of helminths might affect the likelihood of malarial immunopathology. Using rodent models of lymphatic filariasis (Litomosoides sigmodontis) and noncerebral malaria (clone AS Plasmodium chabaudi chabaudi), we quantified disease severity, parasitemia, and polyclonal splenic immune responses in BALB/c mice. We found that coinfected mice, particularly those that did not have microfilaremia (Mf), had more severe anemia and loss of body mass than did mice with malaria alone. Even when controlling for parasitemia, malaria was most severe in Mf coinfected mice, and this was associated with increased interferon-g responsiveness. Thus, in Mf mice, filariasis upset a delicate immunological balance in malaria infection and exacerbated malaria-induced immunopathology. Helminth infections are prevalent throughout tropical regions where malaria is transmitted [1–5]. Interactions among infections commonly alter disease severity [6, 7], and malaria-helminth coinfection can either exac

Spectral Theory of Time Dispersive and Dissipative Systems

We study linear time dispersive and dissipative systems. Very often such systems are not conservative and the standard spectral theory can not be applied. We develop a mathematically consistent framework allowing (i) to constructively determine if a given time dispersive system can be extended to a conservative one; (ii) to construct that very conservative system -- which we show is essentially unique. We illustrate the method by applying it to the spectral analysis of time dispersive dielectrics and the damped oscillator with retarded friction. In particular, we obtain a conservative extension of the Maxwell equations which is equivalent to the original Maxwell equations for a dispersive and lossy dielectric medium.Comment: LaTeX, 57 Pages, incorporated revisions corresponding with published versio

Ultracold, radiative charge transfer in hybrid Yb ion - Rb atom traps

Ultracold hybrid ion-atom traps offer the possibility of microscopic manipulation of quantum coherences in the gas using the ion as a probe. However, inelastic processes, particularly charge transfer can be a significant process of ion loss and has been measured experimentally for the Yb$^{+}$ ion immersed in a Rb vapour. We use first-principles quantum chemistry codes to obtain the potential energy curves and dipole moments for the lowest-lying energy states of this complex. Calculations for the radiative decay processes cross sections and rate coefficients are presented for the total decay processes. Comparing the semi-classical Langevin approximation with the quantum approach, we find it provides a very good estimate of the background at higher energies. The results demonstrate that radiative decay mechanisms are important over the energy and temperature region considered. In fact, the Langevin process of ion-atom collisions dominates cold ion-atom collisions. For spin dependent processes \cite{kohl13} the anisotropic magnetic dipole-dipole interaction and the second-order spin-orbit coupling can play important roles, inducing couplingbetween the spin and the orbital motion. They measured the spin-relaxing collision rate to be approximately 5 orders of magnitude higher than the charge-exchange collision rate \cite{kohl13}. Regarding the measured radiative charge transfer collision rate, we find that our calculation is in very good agreement with experiment and with previous calculations. Nonetheless, we find no broad resonances features that might underly a strong isotope effect. In conclusion, we find, in agreement with previous theory that the isotope anomaly observed in experiment remains an open question.Comment: 7 figures, 1 table accepted for publication in J. Phys. B: At. Mol. Opt. Phys. arXiv admin note: text overlap with arXiv:1107.114

When The Silv\u27ry Moon Is Shining On The Goldn Harvest Sheaves

https://digitalcommons.library.umaine.edu/mmb-vp/4831/thumbnail.jp

Three New Long Period X-ray Pulsars Discovered in the Small Magellanic Cloud

The Small Magellanic Cloud is increasingly an invaluable laboratory for studying accreting and isolated X-ray pulsars. We add to the class of compact SMC objects by reporting the discovery of three new long period X-ray pulsars detected with the {\it Chandra X-ray Observatory}. The pulsars, with periods of 152, 304 and 565 seconds, all show hard X-ray spectra over the range from 0.6 - 7.5 keV. The source positions of the three pulsars are consistent with known H-alpha emission sources, indicating they are likely to be Be type X-ray binary star systems.Comment: Accepted for publication in the Astrophysical Journa