Correlated satellite measurements of low-energy electron precipitation and ground based observations of a visible auroral arc

Comparison of Injun 5 satellite measurements of low energy electron precipitation and ground based observations of visible auroral ar

Explorer 12 observations of charged particles in the inner radiation zone

Explorer XII satellite observations of charged particles in inner radiation zon

Observations of charged particle precipitation over the auroral zone during a magnetic substorm

An array of sensitive electrostatic analyzers was launched on the satellite INJUN 5 into a nearly polar, low altitude orbit. A series of three traversals of the northern auroral zone in the local evening sector on 3 December 1968 has provided high energy- and time-resolution observations of low-energy proton and electron intensities within the energy range 50 smaller than E smaller than 15,000 eV before, during and after a polar magnetic substorm. The region of high intensities of plasma-sheet electrons expanded dramatically during the substorm, extending 3.5 deg farther poleward and approximately 4.5 deg farther equatorward relative to that of the preceding pass

Plasmas in Saturn's magnetosphere

The solar wind plasma analyzer on board Pioneer 2 provides first observations of low-energy positive ions in the magnetosphere of Saturn. Measurable intensities of ions within the energy-per-unit charge (E/Q) range 100 eV to 8 keV are present over the planetocentric radial distance range about 4 to 16 R sub S in the dayside magnetosphere. The plasmas are found to be rigidly corotating with the planet out to distances of at least 10 R sub S. At radial distances beyond 10 R sub S, the bulk flows appear to be in the corotation direction but with lesser speeds than those expected from rigid corotation. At radial distances beyond the orbit of Rhea at 8.8 R sub S, the dominant ions are most likely protons and the corresponding typical densities and temperatures are 0.5/cu cm and 1,000,000 K, respectively, with substantial fluctuations. It is concluded that the most likely source of these plasmas in the photodissociation of water frost on the surface of the ring material with subsequent ionization of the products and radially outward diffusion. The presence of this plasma torus is expected to have a large influence on the dynamics of Saturn's magnetosphere since the pressure ratio beta of these plasmas approaches unity at radial distances as close to the planet as 6.5 R sub S. On the basis of these observational evidences it is anticipated that quasi-periodic outward flows of plasma, accompanied with a reconfiguration of the magnetosphere beyond about 6.5 R sub S, will occur in the local night sector in order to relieve the plasma pressure from accretion of plasma from the rings

Novel Phases and Reentrant Melting of Two Dimensional Colloidal Crystals

We investigate two-dimensional (2d) melting in the presence of a one-dimensional (1d) periodic potential as, for example, realized in recent experiments on 2d colloids subjected to two interfering laser beams. The topology of the phase diagram is found to depend primarily on two factors: the relative orientation of the 2d crystal and the periodic potential troughs, which select a set of Bragg planes running parallel to the troughs, and the commensurability ratio p= a'/d of the spacing a' between these Bragg planes to the period d of the periodic potential. The complexity of the phase diagram increases with the magnitude of the commensurabilty ratio p. Rich phase diagram, with ``modulated liquid'', ``floating'' and ``locked floating'' solid and smectic phases are found. Phase transitions between these phases fall into two broad universality classes, roughening and melting, driven by the proliferation of discommensuration walls and dislocations, respectively. We discuss correlation functions and the static structure factor in these phases and make detailed predictions of the universal features close to the phase boundaries. We predict that for charged systems with highly screened short-range interactions these melting transitions are generically reentrant as a function of the strength of the periodic potential, prediction that is in accord with recent 2d colloid experiments. Implications of our results for future experiments are also discussed.Comment: 37 pages, 24 figure

Understanding cervical screening non-attendance among ethnic minority women in England

Background: Women from Black, Asian and Minority Ethnic (BAME) backgrounds are less likely to attend cervical screening than White British women. This study explored socio-demographic and attitudinal correlates of cervical screening non-attendance among BAME women. Methods: Women (30-60 years) were recruited from Indian, Pakistani, Bangladeshi, Caribbean, African and White-British backgrounds (n=720). Participants completed structured interviews. Results: BAME women were more likely to be non-attenders than white British women, (44%-71% vs. 12%) and fell into two groups: the disengaged and the overdue. Migrating to the UK, speaking a language other than English and low education level were associated with being disengaged. Being overdue was associated with older age. Three attitudinal barriers were associated with being overdue for screening among BAME women: low perceived risk of cervical cancer due to sexual inactivity, belief that screening is unnecessary without symptoms and difficulty finding an appointment that fits in with other commitments. Conclusion: BAME non-attenders appear to fall into two groups and interventions for these groups may need to be targeted and tailored accordingly. It is important to ensure that BAME women understand cancer screening is intended for asymptomatic women and that those who have ceased sexual activity may still be at risk