Petrography and Geochemistry of Metals in Almahata Sitta Ureilites

Ureilites are ultramafic achondrites, predominantly composed of olivine and pyroxenes with accessory carbon, metal and sulfide. The majority of ureilites are believed to represent the mantle of the ureilite parent body (UPB) [1]. Although ureilites have lost much of their original metal [2], the metal that remains retains a record of the formative processes. Almahata Sitta is predominantly composed of unbrecciated ureilites with a wide range of silicate compositions [3,4]. As a fall it presents a rare opportunity to examine fresh ureilite metal in-situ, and analyzing their highly siderophile element (HSE) ratios gives clues to their formation. Bulk siderophile element analyses of Almahata Sitta fall within the range observed in other ureilites [5]. We have examined the metals in seven ureilitic samples of Almahata Sitta (AS) and one associated chondrite fragment (AS#25)

New records of marine invertebrates from Ascension Island (central Atlantic)

The sea anemone Telmatactis forskalii, the zoanthid Isaurus tuberculatus, the nemertine Baseodiscus delineatus, the echinoderms Ophiocoma wendtii and Mithrodia clavigera, the molluscs Colubraria canariensis, Glyphepithema turtoni, Tonna pennata, Trivia candidula, Melanella eburnea, Melanella n.sp., Echineulima leucophaes, Stylocheilus striatus, Limaria hians, Pteria hirundo and Callistoctopus macropus, and the crustaceans Tetraclitella sp., Oxynaspis celata, Thor amboinensis and Parribacus antarcticus are recorded from Ascension Island for the first time. A new depth record is given for the sea anemone Telmatactis cricoides. An undescribed shrimp species of the genus Lysmata and the shrimp Lysmata moorei were observed to clean fish at night.info:eu-repo/semantics/publishedVersio

Chemical telemetry of OH observed to measure interstellar magnetic fields

We present models for the chemistry in gas moving towards the ionization front of an HII region. When it is far from the ionization front, the gas is highly depleted of elements more massive than helium. However, as it approaches the ionization front, ices are destroyed and species formed on the grain surfaces are injected into the gas phase. Photodissociation removes gas phase molecular species as the gas flows towards the ionization front. We identify models for which the OH column densities are comparable to those measured in observations undertaken to study the magnetic fields in star forming regions and give results for the column densities of other species that should be abundant if the observed OH arises through a combination of the liberation of H2O from surfaces and photodissociation. They include CH3OH, H2CO, and H2S. Observations of these other species may help establish the nature of the OH spatial distribution in the clouds, which is important for the interpretation of the magnetic field results.Comment: 11 pages, 2 figures, accepted by Astrophysics and Space Scienc

Gravitational Lensing at Millimeter Wavelengths

With today's millimeter and submillimeter instruments observers use gravitational lensing mostly as a tool to boost the sensitivity when observing distant objects. This is evident through the dominance of gravitationally lensed objects among those detected in CO rotational lines at z>1. It is also evident in the use of lensing magnification by galaxy clusters in order to reach faint submm/mm continuum sources. There are, however, a few cases where millimeter lines have been directly involved in understanding lensing configurations. Future mm/submm instruments, such as the ALMA interferometer, will have both the sensitivity and the angular resolution to allow detailed observations of gravitational lenses. The almost constant sensitivity to dust emission over the redshift range z=1-10 means that the likelihood for strong lensing of dust continuum sources is much higher than for optically selected sources. A large number of new strong lenses are therefore likely to be discovered with ALMA, allowing a direct assessment of cosmological parameters through lens statistics. Combined with an angular resolution <0.1", ALMA will also be efficient for probing the gravitational potential of galaxy clusters, where we will be able to study both the sources and the lenses themselves, free of obscuration and extinction corrections, derive rotation curves for the lenses, their orientation and, thus, greatly constrain lens models.Comment: 69 pages, Review on quasar lensing. Part of a LNP Topical Volume on "Dark matter and gravitational lensing", eds. F. Courbin, D. Minniti. To be published by Springer-Verlag 2002. Paper with full resolution figures can be found at ftp://oden.oso.chalmers.se/pub/tommy/mmviews.ps.g

Real-time and non-invasive measurements of cell mechanical behaviour with optical coherence phase microscopy

There is an unmet need in tissue engineering for non-invasive, label-free monitoring of cell mechanical behaviour in their physiological environment. Here, we describe a novel optical coherence phase microscopy (OCPM) set-up which can map relative cell mechanical behaviour in monolayers and 3D systems non-invasively, and in real-time. 3T3 and MCF-7 cells were investigated, with MCF-7 demonstrating an increased response to hydrostatic stimulus indicating MCF-7 being softer than 3T3, demonstrating the ability to provide qualitative data on cell mechanical behaviour. Quantitative measurements of 6% agarose beads have been taken with commercial Cell Scale Microsquisher® system demonstrating that their mechanical properties are in the same order of magnitude of cells, indicating that this is an appropriate test sample for the novel method desctibed

Central serous chorioretinopathy: An evidence-based treatment guideline.

Central serous chorioretinopathy (CSC) is a relatively common disease that causes vision loss due to macular subretinal fluid leakage and it is often associated with reduced vision-related quality of life. In CSC, the leakage of subretinal fluid through defects in the retinal pigment epithelial layer's outer blood-retina barrier appears to occur secondary to choroidal abnormalities and dysfunction. The treatment of CSC is currently the subject of controversy, although recent data obtained from several large randomized controlled trials provide a wealth of new information that can be used to establish a treatment algorithm. Here, we provide a comprehensive overview of our current understanding regarding the pathogenesis of CSC, current therapeutic strategies, and an evidence-based treatment guideline for CSC. In acute CSC, treatment can often be deferred for up to 3-4 months after diagnosis; however, early treatment with either half-dose or half-fluence photodynamic therapy (PDT) with the photosensitive dye verteporfin may be beneficial in selected cases. In chronic CSC, half-dose or half-fluence PDT, which targets the abnormal choroid, should be considered the preferred treatment. If PDT is unavailable, chronic CSC with focal, non-central leakage on angiography may be treated using conventional laser photocoagulation. CSC with concurrent macular neovascularization should be treated with half-dose/half-fluence PDT and/or intravitreal injections of an anti-vascular endothelial growth factor compound. Given the current shortage of verteporfin and the paucity of evidence supporting the efficacy of other treatment options, future studies-ideally, well-designed randomized controlled trials-are needed in order to evaluate new treatment options for CSC

Community indicators: a framework for observing and supporting community activity on Cloudworks

Cloudworks (Cloudworks.ac.uk) is a social networking site designed for sharing, finding and discussing learning and teaching ideas and experiences. Design and development of the site has been based on an iterative analysis, development and implementation approach, underpinned by ongoing research and evaluation. To this end, we have been seeking to establish strategies to enable us to systematically position transactions and emerging patterns of activity on the site so that we can more reliably use the empirical evidence we have gathered (Galley, 2009a, Galley 2009b, Alevizou et al., 2010a, Conole et al, 2010). In this paper we will introduce a framework we have developed for observing and supporting community development on the site. In building our framework we have used empirical evidence gathered from the site, then related it to the literature from a range of disciplines concerned with professional and learning communities. We link research relating to distance learning communities with studies into Computer Mediated Communication (CMC), self-organising communities on the web, and wider research about the nature of learning organisations and continuous professional development. We argue that this framework can be used to capture the development of productive communities in the space (i.e. how far cohesive, productive groups can be said to be emerging or not) and also help focus futur

Horizontal Branch Stars: The Interplay between Observations and Theory, and Insights into the Formation of the Galaxy

We review HB stars in a broad astrophysical context, including both variable and non-variable stars. A reassessment of the Oosterhoff dichotomy is presented, which provides unprecedented detail regarding its origin and systematics. We show that the Oosterhoff dichotomy and the distribution of globular clusters (GCs) in the HB morphology-metallicity plane both exclude, with high statistical significance, the possibility that the Galactic halo may have formed from the accretion of dwarf galaxies resembling present-day Milky Way satellites such as Fornax, Sagittarius, and the LMC. A rediscussion of the second-parameter problem is presented. A technique is proposed to estimate the HB types of extragalactic GCs on the basis of integrated far-UV photometry. The relationship between the absolute V magnitude of the HB at the RR Lyrae level and metallicity, as obtained on the basis of trigonometric parallax measurements for the star RR Lyrae, is also revisited, giving a distance modulus to the LMC of (m-M)_0 = 18.44+/-0.11. RR Lyrae period change rates are studied. Finally, the conductive opacities used in evolutionary calculations of low-mass stars are investigated. [ABRIDGED]Comment: 56 pages, 22 figures. Invited review, to appear in Astrophysics and Space Scienc

The non-invasive biopsy: will urinary proteomics make the renal tissue biopsy redundant?

Proteomics is a rapidly advancing technique which gives a functional insight into gene expression in living organisms. Urine is an ideal medium for study as it is readily available, easily obtained and less complex than other bodily fluids. Considerable progress has been made over the last 5 years in the study of urinary proteomics as a diagnostic tool for renal disease. The advantages of this technique over the traditional renal biopsy include accessibility, safety, the possibility of serial sampling, and the potential for non-invasive prognostic and diagnostic monitoring of disease and an individual’s response to treatment. Urinary proteomics is now moving from a discovery phase in small studies to a validation phase in much larger numbers of patients with renal disease. Whilst there are still some limitations in methodology, which are assessed in this review, the possibility of urinary proteomics replacing the invasive tissue biopsy for diagnosis of renal disease is becoming increasingly realistic