15,168 research outputs found
The gender and access to health services study: final report
Men and women frequently think and behave differently. To observe this is not to suggest anything so absurdly simple as that there are only male and female ways of being; behaviours and thought processes vary according to numerous other factors besides gender. That this is very generally the case however, does mean that there are broad - and often broadly predictable - differences in the way men and women engage with the world. Most commercial organisations understand this very well and plan accordingly. Many public authorities recognise it too and take these differences into account when developing and providing services. For historical reasons however the NHS has rarely done so. It is widely known that there are differences between men and women in the incidence and prevalence of most health conditions. Sometimes there are clear biological reasons for these differences but often there are not. Where biology offers little or no enlightenment, other questions need to be asked: · Do men and women behave in ways that predispose them to particular health conditions to different degrees? · Do men and women use health services with different degrees of effectiveness? · Do men and women receive differerent kinds of service from the NHS? The answer is â yes, these things happen frequently. This is sometimes to the disadvantage of one sex and sometimes to the disadvantage of the other. Sometimes it is to the disadvantage of both. And when these things happen, health outcomes are often affected. This report looks at the reasons why gender is such an important and fundamental determinant of health status and considers the ways in which gender inequalities can be tackled within the present legislative and policy framework. It also brings together the knowledge and evidence in relation to six specific areas of health concerns
Compton scattering in a converging fluid flow - I. The transfer equation
The equations describing Compton scattering in an optically thick fluid flow are derived under the diffusion approximation. The relative importance of the bulk and random motions of the scattering electrons is discussed. In a converging fluid flow of speed u, bulk acceleration of photons dominates thermal Comptonization when u âł (12kT_e/m_e)^(1/2)â
Compton scattering in a converging fluid flow - III Spherical supercritical accretion
Radiative transfer in spherical, supercritical accretion on to a massive black hole is considered. Particular emphasis is placed on the case of non-adiabatic flow in which electron scattering in the converging flow is the dominant source of opacity and photon heating. In escaping diffusively, the photons, which are produced mainly at the trapping radius, undergo âŒ(c/u_(tr))^2 scatterings (where utr is the velocity of the flow at the trapping radius), each one giving a secular fractional energy increase âŒ(u_(tr)/c)^2 and a total average increase of order unity. The emitted radiation spectrum will be a superposition of the locally produced spectra at low frequencies and a power-law at high frequencies. For gas accreting radially with the free-fall speed, the spectral index observed in the outflowing radiation is α~2. Both thermal and non-thermal emission processes are discussed. The conditions under which bulk heating of the photons is important are specified
Hydromagnetic flows from accretion discs and the production of radio jets
We examine the possibility that energy and angular momentum are removed magnetically from accretion discs, by field lines that leave the disc surface and extend to large distances. We illustrate this mechanism by solving the equations of magnetohydrodynamics, assuming infinite conductivity, for axially symmetric, self-similar, cold magnetospheric flow from a Keplerian accretion disc in which the field strength B scales with radius r as B âr^(-5/4). We show that a centrifugally driven outflow of matter from the disc is possible, if the poloidal component of the magnetic field makes an angle of less than 60° with the disc surface. At large distances from the disc, the toroidal component of the magnetic field becomes important and collimates the outflow into a pair of anti-parallel jets moving perpendicular to the disc. Close to the disc, the flow is probably driven by gas pressure in a hot magnetically dominated corona. In this way, magnetic stresses can extract the angular momentum from a thin accretion disc and thus enable matter to be accreted, independently of the presence of viscosity. These jet solutions have the property that most of the power is concentrated within a central core, while most of the angular momentum and magnetic flux is carried near the jet walls. The relevance of this mechanism for the evolution of accretion discs around massive black holes in galactic nuclei and the production of jets in extragalactic radio sources is described
Compton scattering in a converging fluid flow - II. Radiation-dominated shock
The problem of Compton scattering in an optically thick fluid flow in which bulk motion is the dominant source of photon heating is illustrated by analysing a radiation-dominated, plane-parallel shock of speed u with photon to electron ratio greatly exceeding âŒ(m_p/m_e)â . In traversing the shock (of thickness âŒ(c/u) Thomson optical depths), a typical photon experiences (c/u)2 scatterings, each one giving a secular fractional energy increase âŒ(u/c)^2 and a total average increase of order unity. In a converging fluid flow, an exponentially small number of photons are accelerated to an exponentially large energy. Thus, a power-law spectrum will be transmitted at high frequencies. For a shock of Mach number M, bulk acceleration produces a spectral index α = (M^2 â Âœ)(M^2 + 6)(M^2 â 1)^(â2), which tends to unity for a strong shock. The applicability of these results to quasars and the microwave background is briefly discussed
The use of imaging systems to monitor shoreline dynamics
The development of imaging systems is nowadays established as one of the most powerful and reliable tools for monitoring beach morphodynamics. Two different techniques for shoreline detection are presented here and, in one case, applied to the study of beach width oscillations on a sandy beach (Pauanui Beach, New Zealand). Results indicate that images can provide datasets whose length and sample interval are accurate enough to resolve inter-annual and seasonal oscillations, and long-term trends. Similarly, imaging systems can be extremely useful in determining the statistics of rip current occurrence. Further improvements in accuracy and reliability are expected with the recent introduction of digital systems
The Extended Power Law as Intrinsic Signature For a Black Hole
We analyze the exact general relativistic exact integro-differential equation
of radiative transfer describing the interaction of low energy photons with a
Maxwellian distribution of hot electrons in gravitational field of a
Schwarzschild black hole. We prove that due to Comptonization an initial
arbitrary spectrum of low energy photons unavoidably results in spectra
characterized by an extended power-law feature. We examine the spectral index
by using both analytical and numerical methods for a variety of physical
parameters as such the plasma temperature and the mass accretion rate. The
presence of the event horizon as well as the behaviour of the null geodesics in
its vicinity largely determine the dependence of the spectral index on the flow
parameters. We come to the conclusion that the bulk motion of a converging flow
is more efficient in upscattering photons than thermal Comptonization provided
that the electron temperature in the flow is of order of a few keV or less. In
this case, the spectrum observed at infinity consists of a soft component
produced by those input photons that escape after a few scatterings without any
significant energy change and of hard component (described by a power law)
produced by the photons that underwent significant upscattering. The luminosity
of the power-law component is relatively small compared to that of the soft
component. For accretion into black hole the spectral energy index of the
power-law is always higher than one for plasma temperature of order of a few
keV. This result suggests that the bulk motion Comptonization might be
responsible for the power-law spectra seen in the black-hole X-ray sources.Comment: 31 pages, 3 figures; Astrophysical Journal accepte
Study of state-of-the-art static inverter design Final report, 6 Jan. - 6 Jun. 1966
Multiple purpose inverter design based on phase demodulated inverter circuit selected from state-of-the-art assessment of ten inverter circuit
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