Photometric analysis of a space shuttle water venting

Presented here is a preliminary interpretation of a recent experiment conducted on Space Shuttle Discovery (Mission STS 29) in which a stream of liquid supply water was vented into space at twilight. The data consist of video images of the sunlight-scattering water/ice particle cloud that formed, taken by visible light-sensitive intensified cameras both onboard the spacecraft and at the AMOS ground station near the trajectory's nadir. This experiment was undertaken to study the phenomenology of water columns injected into the low-Earth orbital environment, and to provide information about the lifetime of ice particles that may recontact Space Shuttle orbits later. The findings about the composition of the cloud have relevance to ionospheric plasma depletion experiments and to the dynamics of the interaction of orbiting spacecraft with the environment

Which solar EUV indices are best for reconstructing the solar EUV irradiance ?

The solar EUV irradiance is of key importance for space weather. Most of the time, however, surrogate quantities such as EUV indices have to be used by lack of continuous and spectrally resolved measurements of the irradiance. The ability of such proxies to reproduce the irradiance from different solar atmospheric layers is usually investigated by comparing patterns of temporal correlations. We consider instead a statistical approach. The TIMED/SEE experiment, which has been continuously operating since Feb. 2002, allows for the first time to compare in a statistical manner the EUV spectral irradiance to five EUV proxies: the sunspot number, the f10.7, Ca K, and Mg II indices, and the He I equivalent width. Using multivariate statistical methods such as multidimensional scaling, we represent in a single graph the measure of relatedness between these indices and various strong spectral lines. The ability of each index to reproduce the EUV irradiance is discussed; it is shown why so few lines can be effectively reconstructed from them. All indices exhibit comparable performance, apart from the sunspot number, which is the least appropriate. No single index can satisfactorily describe both the level of variability on time scales beyond 27 days, and relative changes of irradiance on shorter time scales.Comment: 6 figures, to appear in Adv. Space. Re

Stereotactic Radiosurgery for Management of Cavernous Malformations

Cavernous malformations (CMs) are abnormal vascular formations of the brain with an estimated incidence of 0.4%-0.8% in the general population.1 CMs have the potential to cause significant morbidity, and have been associated with epileptic seizures, intracranial hemorrhage, and focal neurological deficits.2 Management options include non-treatment, surgical resection, and radiosurgery. We review here the efficacy of different management strategies for cavernous malformations and highlight the specific role of radiosurgery. One of the major complications of cerebral cavernous malformations is intracranial hemorrhage. To optimize patient treatment, it is beneficial to be able to identify patients that are at an increased risk of developing a hemorrhage and would most benefit from intervention. The overall rate of hemorrhage in patients with CMs has been estimated to be 2.25%.3 The rate of hemorrhage, however, is significantly affected by the initial symptom presentation. Patients presenting with a hemorrhage have significantly higher rates of rehemorrhage compared to patients presenting due to incidental findings.3,4 Flemming et al. found that patients presenting with hemorrhage had an overall annual rate of hemorrhage of 6.19% compared to patients presenting without hemorrhage of 0.33%. With increasing use of MR imaging, the percentage of cavernous malformations found incidentally approaches 40%.1 Because the risk of hemorrhage is low in patients with CMs found incidentally, surgical or radiosurgery management may not be indicated. In contrast, patients presenting with symptoms of hemorrhage should be considered for therapeutic intervention due to a high risk for subsequent hemorrhage. One option for the management of cavernous malformations is surgical intervention by CM resection. There is conflicting evidence in the literature regarding the effectiveness of CM resection, likely due to different methodologies used for determining efficacy. When post-operative outcomes are compared to pre-operative values, significant improvement is observed as demonstrated by improvements in the modified Rankin scale and decreased annual hemorrhage rate.5,6 However, the results are limited by the fact that studies did not include a control group of patients that did not receive surgery. A recent retrospective study by Moultrie and colleagues compared the outcome of patients treated with surgical to conservative management. Patients who underwent CM resection had worsened short-term disability scores, increased risk of developing intracranial hemorrhage, and new focal neurologic deficits.

From the transantarctic basin to the ferrar large igneous province-new palynostratigraphic age constraints for triassic-jurassic sedimentation and magmatism in East Antarctica

We present new palynological data from the Transantarctic Mountains that clarify the timing of sedimentary and magmatic processes in the transition from continental deposition of the Beacon Supergroup to emplacement of the Ferrar Large Igneous Province. Samples were collected from twenty-three Triassic and Jurassic sections in the southern area of north Victoria Land (NVL), East Antarctica. Recovered palynomorph assemblages are correlated with the widely used, although informal palynostratigraphic framework established for eastern Australia by Price. The associated Late Triassic-earliest Jurassic zone, APT5, is modified here with a proposed new subdivision: Lower APT5 ("APT5L"; middle-late Norian), Middle APT5 ("APT5M"; Rhaetian), and Upper APT5 ("APT5U"; Hettangian-earliest Sinemurian). We further propose a modification unifying the relevant formal eastern Australian and New Zealand palynostratigraphic zones, with a new Polycingulatisporites crenulatus Association Zone (new zonal status) that includes the P. crenulatus Association Subzone (new subzone; equivalent to APT5L) and the following Foveosporites moretonensis Association Subzone (new subzonal status; equivalent to APT5M). Our palynostratigraphic dating of the NVL assemblages demonstrates that the onset of sedimentation was diachronous in this part of the Transantarctic Basin, ranging from at least the Rhaetian to, in places, early Sinemurian. By lack of evidence for rocks containing APT5U assemblages and by analogy with the few coeval sections in Australia, we infer that the Hettangian interval in NVL is probably consumed by unconformity. Deposition of ashes from distal silicic volcanism commenced in the early Sinemurian and reached a peak phase beginning in middle Pliensbachian (ca 187. Ma), coinciding with the first major magmatic interval of the silicic Chon Aike Province in Patagonia and West Antarctica. Two major episodes of phreatomagmatic activity, driven by shallow-level sill intrusion into sandstone aquifers, occurred during the middle Pliensbachian and during the late Pliensbachian-early Toarcian. The latter episode was closely followed by the first pillow extrusion and local lava effusion. Contrary to some previous studies, we further conclude that all available palynological evidence is compatible with a short-lived emplacement of the plateau-forming Kirkpatrick Basalt at around 180. Ma during the early Toarcian. © 2014 Elsevier B.V

Holistic corpus-based dialectology

This paper is concerned with sketching future directions for corpus-based dialectology. We advocate a holistic approach to the study of geographically conditioned linguistic variability, and we present a suitable methodology, 'corpusbased dialectometry', in exactly this spirit. Specifically, we argue that in order to live up to the potential of the corpus-based method, practitioners need to (i) abandon their exclusive focus on individual linguistic features in favor of the study of feature aggregates, (ii) draw on computationally advanced multivariate analysis techniques (such as multidimensional scaling, cluster analysis, and principal component analysis), and (iii) aid interpretation of empirical results by marshalling state-of-the-art data visualization techniques. To exemplify this line of analysis, we present a case study which explores joint frequency variability of 57 morphosyntax features in 34 dialects all over Great Britain