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I. De Pater, University of California, Berkeley Berkeley, California, USA,
D. P. Hamilton, University of Maryland College Park, Maryland, USA,
M. R. Showalter, SETI Institute Mountain View, California, USA,
H. B. Throop, Planetary Science Institute Tucson, Arizona, USA,
J. A. Burns, Cornell University Ithaca, New York, USA
Six streams of dust were unexpectedly detected by the Ulysses dust detector while this spacecraft was approximately within one AU distance from Jupiter (Grün et al., 1993). Stream durations ranged from hours to days for individual streams. It was clear that the dust in these streams (or bursts), from their directionality of approach to the spacecraft and from the nearness of stream occurrences to Jupiter, emanated from the Jovian system.
Following the original report, Baguhl et al. (1994) later relaxed the criteria for differentiating true dust impacts from “noise pulses” and found almost triple the number of dust impacts in the six streams already found. They also found 5 more streams that, except for one stream, clearly emanated from the Jovian system. The criteria were relaxed in such a way as to not introduce “noise events” into the data.
We examine whether the dark, orbitally-leading hemisphere of Saturn's satellite Iapetus might be coated by debris from low-albedo Phoebe, which orbits retrograde well exterior to Iapetus. Using simplified analytical models along with more complete numerical integrations, we follow the paths of various-sized particles launched gently off Phoebe following collisions with interplanetary and interstellar meteoroids. Micron grains can quickly reach Iapetus since (due to solar radiation) they trace elliptical orbits; larger grains may only hit after their more-circular orbits collapse due to Poynting-Robertson drag; few very large and very small Phoebe grains strike Iapetus. Despite some inconsistencies with observations, we conclude that Phoebe may possibly be the agent that has darkened Iapetus.
We present preliminary analysis of new HST observations of the transiting extrasolar planet HD 209458b. Photometric observations were obtained with the Fine Guidance Sensor (FGS) on the Hubble Space Telescope (HST), providing milli-mag precision and high time resolution (40 Hz). The FGS photometry allows us to derive precise stellar/orbital parameters (ephemeris, inclination, limb darkening) and planetary radius, and also allows a search for the presence of planetary rings and satellites. We discuss preliminary results and two approaches to modelling the observations.
Shallow ice cores were obtained from widely distributed sites across the West Antarctic ice sheet, as part of the United States portion of the International Trans-Antarctic Scientific Expedition (US ITASE) program. The US ITASE cores have been dated by annual-layer counting, primarily through the identification of summer peaks in non-sea-salt sulfate (nssSO42–) concentration. Absolute dating accuracy of better than 2 years and relative dating accuracy better than 1 year is demonstrated by the identification of multiple volcanic marker horizons in each of the cores, Tambora, Indonesia (1815), being the most prominent. Independent validation is provided by the tracing of isochronal layers from site to site using high-frequency ice-penetrating radar observations, and by the timing of mid-winter warming events in stable-isotope ratios, which demonstrate significantly better than 1 year accuracy in the last 20 years. Dating precision to ±1 month is demonstrated by the occurrence of summer nitrate peaks and stable-isotope ratios in phase with nssSO42–, and winter-time sea-salt peaks out of phase, with phase variation of <1 month. Dating precision and accuracy are uniform with depth, for at least the last 100 years.
An updated compilation of published and new data of major-ion (Ca, Cl, K, Mg, Na, NO3, SO4) and methylsulfonate (MS) concentrations in snow from 520 Antarctic sites is provided by the national ITASE (International Trans-Antarctic Scientific Expedition) programmes of Australia, Brazil, China, Germany, Italy, Japan, Korea, New Zealand, Norway, the United Kingdom, the United States and the national Antarctic programme of Finland. The comparison shows that snow chemistry concentrations vary by up to four orders of magnitude across Antarctica and exhibit distinct geographical patterns. The Antarctic-wide comparison of glaciochemical records provides a unique opportunity to improve our understanding of the fundamental factors that ultimately control the chemistry of snow or ice samples. This paper aims to initiate data compilation and administration in order to provide a framework for facilitation of Antarctic-wide snow chemistry discussions across all ITASE nations and other contributing groups. The data are made available through the ITASE web page (http://www2.umaine.edu/itase/content/syngroups/snowchem.html) and will be updated with new data as they are provided. In addition, recommendations for future research efforts are summarized.
VLBI observations of the nucleus of Centaurus A were made in April, 1982 at two frequencies with an array of five Australian radio antennas as part of the Southern Hemisphere VLBI Experiment (SHEVE). Observations were undertaken at 2.29 GHz with all five antennas, while only two were operational at 8.42 GHz. The 2.29 GHz data yielded significant information on the structure of the nuclear jet. At 8.42 GHz a compact unresolved core was detected as well.
Six radio telescopes were operated as the first southern hemisphere VLBI array in April and May 1982. Observations were made at 2.3 and 8.4 Ghz. This array produced VLBI images of 28 southern hemisphere radio sources, high accuracy VLBI geodesy between southern hemisphere sites, and subarcsecond radio astrometry of celestial sources south of declination −45 degrees. This paper discusses only the astrophysical aspects of the experiment.
Mental health stigma and discrimination are significant problems. Common coping orientations include: concealing mental health problems, challenging others and educating others. We describe the use of common stigma coping orientations and explain variations within a sample of English mental health service users.
Cross-sectional survey data were collected as part of the Viewpoint survey of mental health service users’ experiences of discrimination (n = 3005). Linear regression analyses were carried out to identify factors associated with the three stigma coping orientations.
The most common coping orientation was to conceal mental health problems (73%), which was strongly associated with anticipated discrimination. Only 51% ever challenged others because of discriminating behaviour, this being related to experienced discrimination, but also to higher confidence to tackle stigma.
Although stigma coping orientations vary by context, individuals often choose to conceal problems, which is associated with greater anticipated and experienced discrimination and less confidence to challenge stigma. The direction of this association requires further investigation.
Cryogenic detectors for gravitational wave astronomy promise greatly improved sensitivity over room temperature detectors. The 3 mK detector which we have under construction should give an improvement of 106 over existing detectors. The cryogenic antennae are described and the calculated low temperature performance is detailed. New superconducting instrumentation is described.
Oropharyngeal cancer is increasing in prevalence in the UK and this is thought to be due to the emergence of disease related to human papilloma virus.
A literature review was conducted on the diagnosis and latest management of oropharyngeal cancer.
In non-smokers, human papilloma virus related disease is thought to have better outcomes, but this casts doubt on previous research which did not stratify patients according to human papilloma virus status. However, this theory provides a route for researchers to risk stratify and de-escalate treatments, and hence reduce treatment burden. In addition, the emergence of minimally invasive transoral techniques allows surgeons to remove large tumours without many of the side effects associated with radical (chemo)radiotherapy.
The emergence of human papilloma virus related disease and minimally invasive techniques have led the clinical and academic community to reconsider how oropharyngeal cancer is managed. Comparative and risk-stratification trials are urgently required and ongoing.
The Southern Hemisphere VLBI Experiment (SHEVE) program is aimed at producing high-resolution images of southern radio sources. The radio telescopes of the present SHEVE array are described below and some recent results presented.
Observations at a number of frequencies indicate that for at least two pulsars the average pulse shape has a slow but quite definite frequency dependence. Figure 1 shows average pulse shapes for CP 1919, CP 0950 and CP 1133. With the exception of those at 408 MHz these results were obtained at Parkes. The 408 MHz pulse shapes were obtained at Jodrell Bank by Lyne and Rickett. Circumstances of the observations are listed in Table I. Linearly polarized feeds were used at all frequencies.
The supernova SN1986j resembles the prototypical Type V supernova SN1961v in the relatively slow ∼1000km/s expansion velocity, the slow light curve, and also in the Hα dominated spectrum. The optical spectrum is similar to the spectra of some novae, and some OB stars with massive winds, being characteristic of a nebular plasma at about 1010cm−3 and 104K. What makes SN1986j exceptional is its tremendous radio luminosity, the brightest radio supernova observed to date. The radio emission indicates the presence of a massive circumstellar wind, with which the SN ejecta are now colliding. Since the cooling time of the optically emitting gas is about an hour, a heat source is required to power the light curve. Shocks moving back into the ejecta offer a natural heat source, and account quantitatively for the observed luminosity and spectral character of SN1986j. The large Hα/Hβ ratio is attributed to trapping of Ly α, which pumps the n = 2 level of hydrogen, causing a finite optical depth in Balmer lines, and converting Hβ to Pα and Hα. The ratio of the derived H(n = 2) density and column density yields a size for the Hα emitting region consistent with the thickness of a cooling shock, but less than 10−7 of the 1017cm VLBI size. An important discriminant between shock models and photoionization models of the spectrum is that shocks predict Lyman 2-photon emission. The mass of the optically emitting material in SN1986j is about 1M⊙, substantially less than the 2000 M⊙ argued in the case of SN1961v by Utrobin. However, there may be, and probably is, considerably more unobserved ejecta. This material should reveal itself as the remnant of SN1986j continues to evolve.
Cricopharyngeal dysfunction following head and neck cancer treatment may lead to a significant reduction in oral intake. Carbon dioxide laser is an established procedure for the treatment of non-malignant cricopharyngeal disorders. We report our experience of laser cricopharyngeal myotomy with objective swallowing outcome measures, before and after treatment.
We identified 11 patients who had undergone carbon dioxide laser cricopharyngeal myotomy for dysphagia following radiotherapy, with or without chemotheraphy between January 2006 and July 2011. We analysed the swallowing outcomes following carbon dioxide laser cricopharyngeal myotomy by retrospective grading of pre- and post-procedure videofluoroscopic swallowing study of liquids, using the validated Modified Barium Swallow Impairment Profile.
The median Modified Barium Swallow Impairment Profile score was 13 pre-myotomy and 10 post-myotomy. This difference between scores was non-significant (p = 0.41). The median, cricopharyngeal-specific Modified Barium Swallow Impairment Profile variables (14 and 17) improved from 3 to 2, but were similarly non-significant (p = 0.16). We observed the improved Modified Barium Swallow Impairment Profile scores post-procedure in the majority of patients.
Endoscopic carbon dioxide laser cricopharyngeal myotomy remains a viable option in treatment-related cricopharyngeal dysfunction; its targeted role requires further prospective study. Objective analysis of the technique can be reported using the validated Modified Barium Swallow Impairment Profile.
Background: Ependymomas are rare tumors of the central nervous system whose management is controversial. This population-based study of adults and children with ependymoma aims to (1) identify clinical and treatment-related factors that impact survival and (2) determine if postoperative radiotherapy (RT) can improve survival of patients with subtotal resection (STR) to levels similar to patients who had gross total resection (GTR). Methods: This retrospective population-based study evaluated 158 patients with ependymoma diagnosed between 1975-2007 in Alberta, Canada. Results: Younger patients (<7 years of age) were more likely to be diagnosed with grade III tumors compared with adults in whom grade I tumors were more common (p=0.003). Adults were more likely to have spinally located tumors compared to young children whose tumors were typically found in the brain. Overall, young children with ependymoma were more likely to die than older children or adults (p=0.001). An equivalent number of patients underwent GTR as compared with STR (48% vs 45%, respectively). Overall, older age, spinal tumor location, lower grade, and GTR were associated with improved progression free survival but only GTR was associated with significant improvement in overall survival. Median survival after STR and RT was 82 months compared with 122 months in patients who had GTR (p=0.0022). Conclusions: This is the first Canadian population-based analysis of patients with ependymoma including adults and children. Extent of resection appears to be the most important factor determining overall survival. Importantly, the addition of RT to patients initially treated with STR does not improve survival to levels similar to patients receiving GTR.
When the circulation of the blood is observed in the transparent tissues of an animal, it is noticed that the coloured corpuscles run in the axial part of the stream, while the colourless mostly keep in the peripheral still current. The coloured corpuscles move much faster than the colourless; they have also a gliding, while the colourless have a rotatory, motion. Further, if the frog's web be examined in the upright position, with the microscope inclined so as to be horizontal with the table on which it is placed, it is noticed that the great majority of the leucocytes not only flow in the peripheral stream, but on the upper surface of the vessel. From a number of observations of blood-vessels in the frog's web, examined in this position, it was found that for every 13 leucocytes which are seen running along the lower surface, there is an average of 92 on the upper. In fact, the only time, apparently, in which a leucocyte gets to the lower surface, is in passing round a curved capillary, where, in changing its position, the stream of coloured corpuscles prevents it from gaining the upper surface of the vessel for some distance. If followed along the stream, sufficiently far, such a leucocyte is eventually found to make its way through the stream of coloured blood-corpuscles and to gain the upper surface of the vessel.
Methods.—The great difficulties heretofore encountered in investigating the course of nerve fibres in the brain have been, firstly, the want of a method of preparation by which their gross anatomy could be thoroughly exposed, and, secondly, the failure of any previously known process of staining to satisfactorily indicate their direction on microscopic examination. In endeavouring to collect reliable data from the records of lesions of the human brain, it becomes only too evident that until more efficient methods of localising lesions be adopted than those generally in use at the present day, little can possibly be added to the knowledge we already possess.