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We present results from a multiwavelength study of the blazar PKS 1954–388 at radio, UV, X-ray, and gamma-ray energies. A RadioAstron observation at 1.66 GHz in June 2012 resulted in the detection of interferometric fringes on baselines of 6.2 Earth-diameters. This suggests a source frame brightness temperature of greater than 2 × 1012 K, well in excess of both equipartition and inverse Compton limits and implying the existence of Doppler boosting in the core. An 8.4-GHz TANAMI VLBI image, made less than a month after the RadioAstron observations, is consistent with a previously reported superluminal motion for a jet component. Flux density monitoring with the Australia Telescope Compact Array confirms previous evidence for long-term variability that increases with observing frequency. A search for more rapid variability revealed no evidence for significant day-scale flux density variation. The ATCA light-curve reveals a strong radio flare beginning in late 2013, which peaks higher, and earlier, at higher frequencies. Comparison with the Fermi gamma-ray light-curve indicates this followed ~ 9 months after the start of a prolonged gamma-ray high-state—a radio lag comparable to that seen in other blazars. The multiwavelength data are combined to derive a Spectral Energy Distribution, which is fitted by a one-zone synchrotron-self-Compton (SSC) model with the addition of external Compton (EC) emission.
A megaslump at Batagaika, in northern Yakutia, exposes a remarkable stratigraphic sequence of permafrost deposits ~50–80 m thick. To determine their potential for answering key questions about Quaternary environmental and climatic change in northeast Siberia, we carried out a reconnaissance study of their cryostratigraphy and paleoecology, supported by four rangefinder 14C ages. The sequence includes two ice complexes separated by a unit of fine sand containing narrow syngenetic ice wedges and multiple paleosols. Overall, the sequence developed as permafrost grew syngenetically through an eolian sand sheet aggrading on a hillslope. Wood remains occur in two forest beds, each associated with a reddened weathering horizon. The lower bed contains high amounts of Larix pollen (>20%), plus small amounts of Picea and Pinus pumila, and is attributed to interglacial conditions. Pollen from the overlying sequence is dominated by herbaceous taxa (~70%–80%) attributed to an open tundra landscape during interstadial climatic conditions. Of three hypothetical age schemes considered, we tentatively attribute much of the Batagaika sequence to Marine Oxygen Isotope Stage (MIS) 3. The upper and lower forest beds may represent a mid–MIS 3 optimum and MIS 5, respectively, although we cannot discount alternative attributions to MIS 5 and 7.
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.
This triennium has in general not been one of spectacular new developments in photometric of polarimetric techniques; rather, existing techniques have been improved and are being exploited by more observatories than before. For this reason, the previous report (31.113.097) should be consulted for a broad survey of the subject, while the present has the character of a progress report.
Our knowledge of the universe comes from recording the photon and particle fluxes incident on the Earth from space. We thus require sensitive measurement across the entire energy spectrum, using large telescopes with efficient instrumentation located on superb sites. Technological advances and engineering constraints are nearing the point where we are recording as many photons arriving at a site as is possible. Major advances in the future will come from improving the quality of the site. The ultimate site is, of course, beyond the Earth’s atmosphere, such as on the Moon, but economic limitations prevent our exploiting this avenue to the degree that the scientific community desires. Here we describe an alternative, which offers many of the advantages of space for a fraction of the cost: the Antarctic Plateau.
We have monitored the 610 MHz flux density of 21 pulsars on a daily basis for five years. The flux density time series for these pulsars range from nearly constant for the most distant and heavily scattered pulsars to rapidly varying, saturated time series for more nearby pulsars. The measured stability of the flux density from the most distant pulsars (variations less than 5%) implies that the average radio emission from pulsars, before it has been affected by propagation through the ISM, is constant in strength over five years. The flux variations for 12 of the pulsars are consistent with a Kolmogorov turbulence spectrum over a range of more than three orders of magnitude in scattering strength, with no detectable presence of an inner scale (si ≥ 107cm). The flux variations are greater than predicted by this model for five pulsars – including the Crab and Vela – but this group is consistent with a Kolmogorov spectrum and an inner scale of ∼ 1010cm.
We report on the first results of our ground-survey of H2O masers to establish a list of suitable candidates for space-VLBI observations. Due to the large VSOP/HALCA baselines and its limited sensitivity only very strong and compact sources will be detected. The best candidates from this survey will be part of The VSOP Survey which intends to observe a large number of continuum and maser sources. This systematic and uniform survey, of a large number of sources, will be invaluable in determining the properties of the sub-milliarcsecond emission from maser sources.
Field studies were carried out to assess diel activity patterns of the balsam gall midge, Paradiplosis tumifex Gagné (Diptera: Cecidomyiidae) in 2012, and its inquiline, Dasineura balsamicola (Lintner) (Diptera: Cecidomyiidae) in 2013, in a young balsam fir (Abies balsamea (Linnaeus) Miller) stand in New Brunswick, Canada. Both gallmaker and inquiline are most active during the afternoon/evening hours (17:00–22:00 hours). Male gallmaker activity was largely confined to the space below the crown and typically involved short periods of flight of <30 seconds. Calling and mating by the gallmaker occurred at ground level and were followed by dispersal of females to the vegetative crown. Female gallmakers were typically observed in the tree crown beginning in early afternoon, with peak oviposition occurring between 20:00 and 21:00 hours. Female inquilines displayed similar activity patterns, although no calling or mating were observed. Moreover, inquiline flight and foraging for oviposition sites were more active than the gallmaker, with shorter rest periods and more buds visited than the gallmaker. Our results indicate that population monitoring should focus on female gallmakers as they fly during the evening. Also, before any treatment application, care should be taken to accurately identify the insects to ensure that the inquiline is not inadvertently killed.
In recent decades, the development of computerised neurocognitive screening has revolutionised medical management in the sports concussion arena by making possible preseason (baseline) testing of large numbers of athletes, and repeat follow-up testing of the concussed athlete, to monitor recovery and facilitate safe return-to-play decisions (Moser et al., 2007). The aim of this chapter is to introduce the most widely employed instrument of this genre, the ImPACT (Immediate Postconcussion Assessment and Cognitive Testing) test (Iverson, Lovell & Collins, 2002), and to review the available South African normative research data in respect of the instrument to date. While the test has potential for wide application beyond the sports concussion arena (as discussed in the concluding section of this chapter), its development within the sports injury context calls for background detail in this regard.
Mild traumatic brain injury (concussion) in sport
Mild traumatic brain injury (MTBI), typically referred to as ‘concussion’ in the sports arena, is a common feature amongst both amateur and professional sports alike (Cassidy, Carroll, Peloso, Borg & Von Holst, 2004). While once considered to be a ‘routine risk’ associated with participation in the game, the impact of these injuries has gained significant international interest and concern amongst sports and health professionals in the past three decades (Barth et al., 1989; Collins, Lovell & McKeag, 1999; Shuttleworth-Edwards, Border, Reid & Radloff, 2004), and is currently considered by the Centers for Disease Control and Prevention (CDC, 1997) to be of epidemic proportions. The incidence of the concussive injury varies widely depending on the sport, such that in one comparative high school study US football accounted for 63 per cent of all cases, wrestling for 10.5 per cent, girls’ soccer for 6.2 per cent, boys’ soccer for 5.7 per cent, girls’ basketball for 5.2 per cent, boys’ basketball for 4.2 per cent, softball for 2.1 per cent, baseball for 1.2 per cent, field hockey for 1.1 per cent and volleyball for 0.5 per cent (Powell & Barber-Foss, 1999).
The Nakhla meteorite represents basaltic rock from the martian upper crust, with reduced carbon indicative of the ingress of carbonaceous fluids. Study of a terrestrial analogue basalt with reduced carbon from the Ordovician of Northern Ireland shows that remote analysis could detect the carbon using Raman spectroscopy. Analysis of gases released by crushing detects methane-rich fluids in the basalt and especially in cross-cutting carbon-bearing veinlets. The results suggest that automated analysis on Mars could detect the reduced carbon, which may be derived from magmatic and/or meteoritic infall sources.
The future of centimetre and metre-wave astronomy lies with the Square Kilometre Array (SKA), a telescope under development by a consortium of 17 countries that will be 50 times more sensitive than any existing radio facility. Most of the key science for the SKA will be addressed through large-area imaging of the Universe at frequencies from a few hundred MHz to a few GHz. The Australian SKA Pathfinder (ASKAP) is a technology demonstrator aimed in the mid-frequency range, and achieves instantaneous wide-area imaging through the development and deployment of phased-array feed systems on parabolic reflectors. The large field-of-view makes ASKAP an unprecedented synoptic telescope that will make substantial advances in SKA key science. ASKAP will be located at the Murchison Radio Observatory in inland Western Australia, one of the most radio-quiet locations on the Earth and one of two sites selected by the international community as a potential location for the SKA. In this paper, we outline an ambitious science program for ASKAP, examining key science such as understanding the evolution, formation and population of galaxies including our own, understanding the magnetic Universe, revealing the transient radio sky and searching for gravitational waves.
Herpes virus infections can cause cognitive impairment during and after acute encephalitis. Although chronic, latent/persistent infection is considered to be relatively benign, some studies have documented cognitive impairment in exposed persons that is untraceable to encephalitis. These studies were conducted among schizophrenia (SZ) patients or older community dwellers, among whom it is difficult to control for the effects of co-morbid illness and medications. To determine whether the associations can be generalized to other groups, we examined a large sample of younger control individuals, SZ patients and their non-psychotic relatives (n=1852).
Using multivariate models, cognitive performance was evaluated in relation to exposures to herpes simplex virus type 1 (HSV-1), herpes simplex virus type 2 (HSV-2) and cytomegalovirus (CMV), controlling for familial and diagnostic status and sociodemographic variables, including occupation and educational status. Composite cognitive measures were derived from nine cognitive domains using principal components of heritability (PCH). Exposure was indexed by antibodies to viral antigens.
PCH1, the most heritable component of cognitive performance, declines with exposure to CMV or HSV-1 regardless of case/relative/control group status (p = 1.09 × 10−5 and 0.01 respectively), with stronger association with exposure to multiple herpes viruses (β = −0.25, p = 7.28 × 10−10). There were no significant interactions between exposure and group status.
Latent/persistent herpes virus infections can be associated with cognitive impairments regardless of other health status.