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The rocky shores of the north-east Atlantic have been long studied. Our focus is from Gibraltar to Norway plus the Azores and Iceland. Phylogeographic processes shape biogeographic patterns of biodiversity. Long-term and broadscale studies have shown the responses of biota to past climate fluctuations and more recent anthropogenic climate change. Inter- and intra-specific species interactions along sharp local environmental gradients shape distributions and community structure and hence ecosystem functioning. Shifts in domination by fucoids in shelter to barnacles/mussels in exposure are mediated by grazing by patellid limpets. Further south fucoids become increasingly rare, with species disappearing or restricted to estuarine refuges, caused by greater desiccation and grazing pressure. Mesoscale processes influence bottom-up nutrient forcing and larval supply, hence affecting species abundance and distribution, and can be proximate factors setting range edges (e.g., the English Channel, the Iberian Peninsula). Impacts of invasive non-native species are reviewed. Knowledge gaps such as the work on rockpools and host–parasite dynamics are also outlined.
Spectrum analysis in the ultrasoft X-ray region is complicated by the fact that this radiation is almost totally absorbed in any medium. This has necessitated spectrometer components which minimize this effect. Nondispersive and total reflection techniques, though high in speed, lack good resolution and in the case of the latter, are usually restricted to analysis of elements differing by at least three atomic numbers.
Diffracting media which have proven successful are the long-chain organic crystals and gratings at grazing incidence. The grating is superior to the organic crystal concerning resolution and dispersion and has proven to be comparable arid in some cases better for peak intensity and line-to-background ratios.
Lightly-ruled gratings have been used for many years, but little attention has been given the blazed grating until recently. Since the critical angle of total reflection for a given material is wavelength-dependent, it may be utilized to discriminate against shorter wavelengths and thus improve line-to-background ratios. The optimum conditions for sensitivity, then, would be to relate the input angle to the blaze angle and vary the input angle as a function of wavelength, thereby maximizing the line intensity or the line-to-backgrourid ratio as required.
Several gratings with varying blaze angles and surface finishes are evaluated with O Kα (23.7Å) and C Kα (44Å) radiation.
The importance of groove profile is emphasized by comparing the profile as determined by the electron microscope with the experimental evidence. The variation of diffraction efficiency with wavelength and input angle is then considered theoretically and compared with experimental results.
Measurements in the infrared wavelength domain allow direct assessment of the physical state and energy balance of cool matter in space, enabling the detailed study of the processes that govern the formation and evolution of stars and planetary systems in galaxies over cosmic time. Previous infrared missions revealed a great deal about the obscured Universe, but were hampered by limited sensitivity.
SPICA takes the next step in infrared observational capability by combining a large 2.5-meter diameter telescope, cooled to below 8 K, with instruments employing ultra-sensitive detectors. A combination of passive cooling and mechanical coolers will be used to cool both the telescope and the instruments. With mechanical coolers the mission lifetime is not limited by the supply of cryogen. With the combination of low telescope background and instruments with state-of-the-art detectors SPICA provides a huge advance on the capabilities of previous missions.
SPICA instruments offer spectral resolving power ranging from R ~50 through 11 000 in the 17–230 μm domain and R ~28.000 spectroscopy between 12 and 18 μm. SPICA will provide efficient 30–37 μm broad band mapping, and small field spectroscopic and polarimetric imaging at 100, 200 and 350 μm. SPICA will provide infrared spectroscopy with an unprecedented sensitivity of ~5 × 10−20 W m−2 (5σ/1 h)—over two orders of magnitude improvement over what earlier missions. This exceptional performance leap, will open entirely new domains in infrared astronomy; galaxy evolution and metal production over cosmic time, dust formation and evolution from very early epochs onwards, the formation history of planetary systems.
One of the seminar topics scheduled for the summer of 1955 by the Society for American Archaeology was “The American Southwest: A Problem in Cultural Isolation.” The assignment was to “… examine the assumption that these Southwestern cultures resulted from local acceptance and development of generalized and/or specific traits which can be isolated in distant cultural contexts at earlier times than their climactic developments can be observed in the Southwest.”
The Chronological relationship of the Adena and Hopewell cultures and their placement within the temporal column of North American prehistory was considered of sufficient importance by the Committee on Radioactive Carbon 14 to warrant a special effort to obtain dates. Individuals and institutions in the Mississippi Valley were requested to provide samples, with the result that specimens were submitted from an Adena site in Kentucky (126) and one in Ohio (214). Two specimens from a Tchefuncte culture midden in Louisiana thought to be of comparable age and typology to Adena (150 and 151) were processed in order to provide information on a common cultural level over a considerable area. A total of six specimens from the Hopewellian level were dated. These comprise runs on three different kinds of organic material from mound 25 of the Hopewell group (137-139), Ross County, Ohio; a specimen from mound 9 of the Havana group in Mason County, Illinois (152); material from Bynum, a Hopewell period site in northeast Mississippi (154); and from the Crooks site, a Marksville mound in LaSalle Parish, Louisiana (143). It was believed, before the samples were dated, that this would afford satisfactory information not only on the time position of Adena and Hopewell but might also clear up the question as to the priority of appearance in the north or the south of those cultural influences which produced the general stages of early to middle Woodland and their local representations.
This Brief Paper will serve as an introduction to an examination of the ceramic material excavated by Giddings at the site of Iyatayet on Cape Denbigh in Norton Sound in northwestern Alaska. Norton Sound is located in the northeastern Bering Sea. The site has become well known because of the Cape Denbigh flint complex which occurred in the lowest level of the site and which was separated from the pottery levels above by a sterile zone of varying thickness, from 2 to 18 inches, made up of laminated, sandy clay (Giddings, 1949, 1951). This sterile zone was contorted and has been tentatively interpreted as indicating a colder climate than the present.
The upper sections of the excavated area at Iyatayet give every indication of having been intermittently occupied from relatively recent times back through Eskimo history to approximately 2000 years ago. The top layers of the site contain the same artifacts and ceramic materials as those found on the neighboring Nukleet site which is thought to date roughly around 1500 to 1600 A.D. Other materials from the upper zone are suggestive of Early Punuk.
Background:ATP8A2 mutations have only recently been associated with human disease. We present the clinical features from the largest cohort of patients with this disorder reported to date. Methods: An observational study of 9 unreported and 2 previously reported patients with biallelic ATP8A2 mutations was carried out at multiple centres. Results: The mean age of the cohort was 9.4 years old (range: 2.5-28 yrs). All patients demonstrated developmental delay, severe hypotonia and movement disorders: chorea/choreoathetosis (100%), dystonia (27%) or facial dyskinesia (18%). Hypotonia was apparent at birth (70%) or before 6 months old (100%). Optic atrophy was observed in 75% of patients who had a funduscopic examination. MRI of the brain was normal for most patients with a small proportion showing mild cortical atrophy (30%), delayed myelination (20%) and/or hypoplastic optic nerves (20%). Epilepsy was seen in two older patients. Conclusions:ATP8A2 gene mutations have emerged as a cause of a novel phenotype characterized by developmental delay, severe hypotonia and hyperkinetic movement disorders. Optic atrophy is common and may only become apparent in the first few years of life, necessitating repeat ophthalmologic evaluation. Early recognition of the cardinal features of this condition will facilitate diagnosis of this disorder.
Studies estimating the human health impact of the foodborne disease often include estimates of the number of gastroenteritis hospitalisations. The aims of this study were to examine the degree to which hospital discharge data underreport hospitalisations due to bacterial gastroenteritis and to estimate the frequency of stool sample submission among patients presenting with gastroenteritis. Using linked laboratory and hospital discharge data from a healthcare organisation and its affiliated hospital, we examined the International Classification of Disease (ICD-9-CM) diagnosis codes assigned to hospitalised adults with culture-confirmed Campylobacter, Salmonella, or Escherichia coli O157 infections and determined the frequency of stool sample submission. Among 138 hospitalised patients with culture-confirmed infections, 43% of Campylobacter patients, 56% of Salmonella patients and 35% of E. coli O157 patients had that pathogen-specific code listed on the discharge record. Among patients without their infection listed as a diagnosis, 65% were assigned a nonspecific gastroenteritis code. Submitting a specimen for culture ⩾3 days before discharge was significantly associated with having the pathogen-specific diagnosis listed. Of 6181 patients assigned a nonspecific gastroenteritis code, 69% had submitted a stool sample for bacterial culture. This study can be used to understand differences and adjust for the underreporting and underdiagnosed of Campylobacter, Salmonella and E. coli O157 in hospital discharge and surveillance data, respectively.
The mid-infrared range contains many spectral features associated with large molecules and dust grains such as polycyclic aromatic hydrocarbons and silicates. These are usually very strong compared to fine-structure gas lines, and thus valuable in studying the spectral properties of faint distant galaxies. In this paper, we evaluate the capability of low-resolution mid-infrared spectroscopic surveys of galaxies that could be performed by SPICA. The surveys are designed to address the question how star formation and black hole accretion activities evolved over cosmic time through spectral diagnostics of the physical conditions of the interstellar/circumnuclear media in galaxies. On the basis of results obtained with Herschel far-infrared photometric surveys of distant galaxies and Spitzer and AKARI near- to mid-infrared spectroscopic observations of nearby galaxies, we estimate the numbers of the galaxies at redshift z > 0.5, which are expected to be detected in the polycyclic aromatic hydrocarbon features or dust continuum by a wide (10 deg2) or deep (1 deg2) blind survey, both for a given observation time of 600 h. As by-products of the wide blind survey, we also expect to detect debris disks, through the mid-infrared excess above the photospheric emission of nearby main-sequence stars, and we estimate their number. We demonstrate that the SPICA mid-infrared surveys will efficiently provide us with unprecedentedly large spectral samples, which can be studied further in the far-infrared with SPICA.
The blue continuum of the eclipsing polar UZ For is dominated by single- or double-peaked emission from He ii, He i and the Balmer lines. The red spectrum shows weak emission from the Na i doublet at λ 8183 and 8194 Å and strong emission from the Ca ii lines at λ 8498 and 8542 Å. Doppler tomography of the strongest emission features reveals the presence of emission from the irradiated face of the secondary star, the threading region, and the ballistic and magnetically confined accretion stream. We have obtained 28 new eclipse times of UZ For during 2011–2016 as part of our eclipse timing follow-up programme to test the two-planet model proposed to explain variations in the eclipse times of UZ For.
The Hubble Source Catalog (HSC) combines lists of sources detected on images obtained with the WFPC2, ACS and WFC3 instruments aboard the Hubble Space Telescope (HST) and now available in the Hubble Legacy Archive. The catalogue contains time-domain information for about two million of its sources detected using the same instrument and filter on at least five HST visits. The Hubble Catalog of Variables (HCV) aims to identify HSC sources showing significant brightness variations. A magnitude-dependent threshold in the median absolute deviation of photometric measurements (an outlier-resistant measure of light-curve scatter) is adopted as the variability detection statistic. It is supplemented with a cut in χred2 that removes sources with large photometric errors. A pre-processing procedure involving bad image identification, outlier rejection and computation of local magnitude zero-point corrections is applied to the HSC light-curves before computing the variability detection statistics. About 52 000 HSC sources have been identified as candidate variables, among which 7,800 show variability in more than one filter. Visual inspection suggests that ∼70% of the candidates detected in multiple filters are true variables, while the remaining ∼30% are sources with aperture photometry corrupted by blending, imaging artefacts or image processing anomalies. The candidate variables have AB magnitudes in the range 15–27m, with a median of 22m. Among them are the stars in our own and nearby galaxies, and active galactic nuclei.
The Berkeley Visible Image Tube (BVIT) has been a user instrument on the SALT 10-m telescope for the past six years. It can observe transient astrophysical phenomena occurring on time-scales of micro-seconds. This overview presented some recent observations of a dMe flare star, and discussed the recent results of our optical Search for Extraterrestrial Intelligence (OSETI) around nearby exoplanet-hosting stars.
We organized Workshop 13, Machine learning for transient classification, into two distinct question-and-answer parts. The first was a so-called ‘idiot session’, in which basic questions about machine learning and artificial intelligence were elicited from the audience. The second focussed discussions on the application of artificial intelligence to transient astronomy.
The workshop proved highly successful. The room was packed, and the many interesting questions and discussions were good preparation for the presentation to be made on ‘machine learning’ during the plenary session the following day.
The workshop clearly reflected the general awareness and excitement in the community for the potential of machine learning in regard to transient detections in astronomy in the era of ZTF, LSST, LIGO and the SKA. Several of the presentations at this Symposium had already been exhibiting specific attention to the roles of machine-learning techniques and products. The extent to which the younger generations were being involved was clearly noticeable, and that augured well for research into workable solutions for astronomy’s ‘Big Data’ problems which – as stated frequently at this conference – are only just around the corner.
Astrosat is a multi-instrument orbiting observatory that was launched in 2015 by the Indian Space Research Organization (ISRO). The same field of view is observed simultaneously at wavelengths ranging from gamma ray to the optical blue. This talk described the observatory’s performance, with emphasis on time-domain studies, and gave examples of results.
HR 6902 was the first target of a systematic study by Griffin (1986, JApA, 7, 195) of binaries showing composite spectra. It is also a well-studied member of the ζ Aur class. ζ Aur systems are long-period eclipsing binaries that are comprised of an evolved giant primary and a hot dwarf companion. Although those component stars have very different effective temperatures they have similar luminosities in the blue and near-UV regions, and hence display a composite spectrum at those wavelengths. In principle the ζ Aur systems are excellent tests of evolutionary and structural stellar models. In recent years the somewhat fragmentary eclipse photometry of HR 6902 has been out-classed by the high-precision continuous monitoring by the space mission CoRoT. HR 6902 was selected as a primary target of its seismology field, because the possible detection of solar-like pulsations in a giant component of a double-lined eclipsing binary could help to calibrate the scaling relation of giant pulsators. Our poster reported the results of a new analysis based on the CoRoT observations and follow-up spectroscopy with HARPS at the ESO 3.6-m telescope at La Silla.
The unprecedented accuracy of the CoRoT photometry enabled us to:
improve drastically the accuracy of the binary orbit and stellar parameters (by a factor ~10 for the radii)
extend the test of validity/calibration of the scaling relations to high stellar mass and radius, and put constraints on the evolutionary state (particularly since this binary is certainly free from tidal effects).
TAOS II is a next-generation occultation survey with the goal of measuring the size distribution of the small end of the Kuiper Belt (objects with diameters 0.5–30 km). Such objects have magnitudes r > 30, and are thus undetectable by direct imaging. The project will operate three telescopes at San Pedro Mártir Observatory in Baja California, México. Each telescope will be equipped with a custom-built camera comprised of a focal-plane array of CMOS imagers. The cameras will be capable of reading out image data from 10,000 stars at a cadence of 20 Hz. The telescopes will monitor the same set of stars simultaneously to search for coincident occultation detections, thus minimising the false-positive rate. This talk described the project, and reported on the progress of the development of the survey infrastructure.
In the last decade great strides have been made in understanding the role of binary stars in the evolution and shaping of planetary nebulæ (PNe). Observational efforts have mainly focused on finding close binaries with orbital periods of 1 day or less. Those close binary systems make up around 1 in 5 PNe, and constitute the youngest accessible window into the aftermath of the critical and unobserved common-envelope (CE) phase of binary-star evolution. The poster focused on our recent work with the High Resolution Spectrograph (HRS) on the Southern African Large Telescope (SALT) to search for long-period binaries in PNe. Considerably less is known about such long-period binaries with orbital periods of weeks to years, but they may be fundamental to improving CE population synthesis models and for determining the total binary fraction of PNe. The queue-mode operation of SALT and the excellent sensitivity and stability of HRS (which is enclosed in a vacuum tank) are ideally suited to detecting binaries with low radial-velocity amplitudes over the expected timescales of weeks to years. Many exciting new discoveries about binaries have already been made in this newly-accessible southern horizon in time-domain astronomy thanks to the many unique advantages of SALT.
The radio sky is full of transients, their time-scales ranging from nanoseconds to decades. Recent developments in technology sensitivity and computing capabilities have opened up the short end of that range, and are revealing a plethora of new phenomenologies. Studies of radio transients were previously restricted to analyses of archived data, but are now including real-time analyses. We focus here on Fast Radio Bursts, discuss and compare the properties of the population, and describe what is to date the only known repeating Fast Radio Burst and its host galaxy. We also review what will be possible with the new instrumentation coming online.