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In recent years, the discovery of massive quasars at
has provided a striking challenge to our understanding of the origin and growth of supermassive black holes in the early Universe. Mounting observational and theoretical evidence indicates the viability of massive seeds, formed by the collapse of supermassive stars, as a progenitor model for such early, massive accreting black holes. Although considerable progress has been made in our theoretical understanding, many questions remain regarding how (and how often) such objects may form, how they live and die, and how next generation observatories may yield new insight into the origin of these primordial titans. This review focusses on our present understanding of this remarkable formation scenario, based on the discussions held at the Monash Prato Centre from November 20 to 24, 2017, during the workshop ‘Titans of the Early Universe: The Origin of the First Supermassive Black Holes’.
The search for life in the Universe is a fundamental problem of astrobiology and modern science. The current progress in the detection of terrestrial-type exoplanets has opened a new avenue in the characterization of exoplanetary atmospheres and in the search for biosignatures of life with the upcoming ground-based and space missions. To specify the conditions favourable for the origin, development and sustainment of life as we know it in other worlds, we need to understand the nature of global (astrospheric), and local (atmospheric and surface) environments of exoplanets in the habitable zones (HZs) around G-K-M dwarf stars including our young Sun. Global environment is formed by propagated disturbances from the planet-hosting stars in the form of stellar flares, coronal mass ejections, energetic particles and winds collectively known as astrospheric space weather. Its characterization will help in understanding how an exoplanetary ecosystem interacts with its host star, as well as in the specification of the physical, chemical and biochemical conditions that can create favourable and/or detrimental conditions for planetary climate and habitability along with evolution of planetary internal dynamics over geological timescales. A key linkage of (astro)physical, chemical and geological processes can only be understood in the framework of interdisciplinary studies with the incorporation of progress in heliophysics, astrophysics, planetary and Earth sciences. The assessment of the impacts of host stars on the climate and habitability of terrestrial (exo)planets will significantly expand the current definition of the HZ to the biogenic zone and provide new observational strategies for searching for signatures of life. The major goal of this paper is to describe and discuss the current status and recent progress in this interdisciplinary field in light of presentations and discussions during the NASA Nexus for Exoplanetary System Science funded workshop ‘Exoplanetary Space Weather, Climate and Habitability’ and to provide a new roadmap for the future development of the emerging field of exoplanetary science and astrobiology.
Surface radiocarbon (Δ14C) in the North Pacific has been monitored using a commercial volunteer observation ship since the early 2000s. Here we report the temporal and spatial variations in Δ14C in the summer surface water when the surface ocean is vertically stratified over a 13-yr period, 2004–2016. The long-term Δ14C decreasing trend after the late 1970s in the subtropical region has continued to the present and the rate of decrease of the Kuroshio and Kuroshio Extension, North Pacific and California current areas is calculated to be –3.3, –5.2 and –3.3 ‰/yr, respectively. After 2012 the Δ14C of the Kuroshio and Kuroshio Extension area, however, has remained at an approximately constant value of around 50‰. The result may indicate that subtropical surface Δ14C in the western North Pacific has reached an equilibrium with atmospheric Δ14CO2. The Δ14C in the subarctic region is markedly lower than values in the subtropical region and it seems that the decreasing tendency of surface Δ14C has changed to an increasing tendency after 2010. The results may indicate that bomb-produced 14C, which has accumulated below the mixed layer in the past few decades, has been entrained into the surface layer by deep convection.
This study focused on parotid gland tumours diagnosed as benign by fine-needle aspiration cytology and investigated the necessity of frozen section biopsy.
There were 104 cases of parotid gland tumour where fine-needle aspiration cytology was benign and frozen section biopsy was subsequently performed, between April 2006 and June 2016. In this retrospective study, the results of frozen section biopsy were analysed and compared with the final histological diagnosis.
Among the 104 cases diagnosed as benign by fine-needle aspiration cytology, 102 cases and 2 cases were diagnosed as benign and malignant, respectively, by frozen section biopsy. The final histological diagnoses showed that 98 cases were benign and 6 cases were malignant. The sensitivity and specificity values of frozen section biopsy in detecting malignant tumours were 33 per cent and 100 per cent, respectively.
The necessity of frozen section biopsy in cases with benign fine-needle aspiration cytology may be low in parotid gland surgery.
Between July of 2012 and December of 2014, 39 patients were enrolled prospectively to investigate the prevalence of glucose transporter 1 (GLUT1) deficiency in a ketogenic diet clinic. None of them had GLUT1 deficiency. All patients seen in the same clinic within the same period were reviewed retrospectively. A total of 18 of these 85 patients had a genetic diagnosis, including GLUT1 deficiency, pathogenic copy number variants, congenital disorder of glycosylation, neuronal ceroid lipofuscinosis type II, mitochondrial disorders, tuberous sclerosis, lissencephaly, and SCN1A-, SCN8A-, and STXBP1-associated epileptic encephalopathies. The prevalence of genetic diagnoses was 21% and prevalence of GLUT1 deficiency was 2.4% in our retrospective cohort study.
Employing a comparative experimental design drawing on over 18,000 interviews across eleven countries on four continents, this article revisits the discussion about the economic and cultural drivers of attitudes towards immigrants in advanced democracies. Experiments manipulate the occupational status, skin tone and national origin of immigrants in short vignettes. The results are most consistent with a Sociotropic Economic Threat thesis: In all countries, higher-skilled immigrants are preferred to their lower-skilled counterparts at all levels of native socio-economic status (SES). There is little support for the Labor Market Competition hypothesis, since respondents are not more opposed to immigrants in their own SES stratum. While skin tone itself has little effect in any country, immigrants from Muslim-majority countries do elicit significantly lower levels of support, and racial animus remains a powerful force.
The purpose of this study was to clarify the association between hand, foot, and mouth disease (HFMD) epidemics and meteorological conditions. We used HFMD surveillance data of all 47 prefectures in Japan from January 2000 to December 2015. Spectral analysis was performed using the maximum entropy method (MEM) for temperature-, relative humidity-, and total rainfall-dependent incidence data. Using MEM-estimated periods, long-term oscillatory trends were calculated using the least squares fitting (LSF) method. The temperature and relative humidity thresholds of HFMD data were estimated from the LSF curves. The average temperature data indicated a lower threshold at 12 °C and a higher threshold at 30 °C for risk of HFMD infection. Maximum and minimum temperature data indicated a lower threshold at 6 °C and a higher threshold at 35 °C, suggesting a need for HFMD control measures at temperatures between 6 and 35 °C. Based on our findings, we recommend the use of maximum and minimum temperatures rather than the average temperature, to estimate the temperature threshold of HFMD infections. The results obtained might aid in the prediction of epidemics and preparation for the effect of climatic changes on HFMD epidemiology.
CRL2688 is suggested to be one of the proto-planetary nebulae which are probably at a stage in which the central star is evolving from the red giant phase with rapid mass loss (Zuckerman 1978). The bipolar shape in both the optical and H2 emission indicates that a dense toroid of dust and gas obscures the star and surrounds the optical emission. The toroid is probably responsible for channelling the mass loss to the polar directions (Ney et al. 1975, Morris 1981, Beckwith et al. 1984). We present the results of mapping observations of CO (J = 1-0) emission from the expanding molecular envelope (Zuckerman et al. 1976, Lo et al. 1976, Knapp et al. 1982, Thronson et al. 1983) of the bipolar reflection nebula CRL2688 using the Nobeyama 45-m telescope with a 1.5″ resolution at a 7″.5 observing spacing.
We report on the formation of shallow junctions with high activation in both n+/p and p+/n Ge junctions using ion implantation and Flash Lamp Annealing (FLA). The shallowest junction depths (Xj) formed for the n+/p and p+/n junctions were 7.6 nm and 6.1 nm with sheet resistances (Rs) of 860 ohms/sq. and 704 ohms/sq., respectively. By reducing knocked-on oxygen during ion implantation in the n+/p junctions, Rs was decreased by between 5% and 15%. The lowest Rs observed was 235 ohms/sq. with a junction depth of 21.5 nm. Hall measurements clearly revealed that knocked-on oxygen degraded phosphorus activation (carrier concentration). In the p+/n Ge junctions, we show that ion implantation damage induced high boron activation. Using this technique, Rs can be reduced from 475 ohms/sq. to 349 ohms/sq. These results indicate that the potential for forming ultra-shallow n+/p and p+/n junctions in the nanometer range in Ge devices using FLA is very high, leading to realistic monolithically-integrated Ge CMOS devices that can take us beyond Si technology.
In 1986, a large avalanche destroyed 11 houses and killed 13 people at Maseguchi, Japan. Previous attempts to model the avalanche were based on the assumption that it was a powder avalanche consisting of snow particles suspended by air turbulence. In this paper, the avalanche is modelled as a dry flowing avalanche with a dense core of flowing material at the base. It is suggested that for a comprehensive explanation of the observed damage and the characteristics of the avalanche deposit, the assumption that the avalanche was a flowing avalanche is more appropriate. The comparison of model results from a flowing versus a powder avalanche is of general interest for avalanche zoning and design of structures in avalanche-threatened areas.
The distribution of H2O masers in the Sgr B2 core was observed with a 2.5′×2.5′ wide field and with 540 km s−1 total velocity coverage by the Nobeyama Millimeter Array. Thirty-nine resolved maser spots were detected with a relative positional accuracy of 0.3″, which are clustered into four separate regions. In Sgr B2 north, the cluster lies at the edge of the continuum ridge. One of the maser spots shows strong and wide velocity-spread emission, suggesting it may correspond to a center of star forming activity. In Sgr B2 main, the strong maser spots are projected just on the face of a compact HII region, and are red-shifted relative to the central velocity of the HII region. There are two possibilities to interpret our results in Sgr B2 (M). One is that the H2O maser spots are distributed around the HII region and are infailing to the HII region. The other is that the H2O maser sources are associated with the cloud in the foreground of the HII region.
We report NH3 observations of the Sgr A complex region including Sgr A West and the 20 km/s and 50 km/s molecular clouds (M–0.13–0.08 and M–0.02–0.07) using the Nobeyama Millimeter Array and the 45m telescope. NH3(1,1) and (2,2) lines were simultaneously observed to estimate the kinetic temperature. Our results suggest strong interaction between the molecular clouds and the continuum sources in the Sgr A complex. The interaction with continuum sources might be an important factor in determining the physical conditions of molecular gas in the galactic center region.
Background: The ketogenic diet (KD) is used to treat severe childhood-onset epileptic encephalopathies, such as Infantile Spasms (IS). Unfortunately, limited resources for KD initiation result in treatment delays. We ask if earlier KD treatment of early-onset drug-resistant epilepsy results in better seizure outcomes. Methods: Children who started KD before age 4 years between 2000-present at SickKids Hospital were identified. Six-month seizure outcome was calculated as percent of pre-diet baseline seizure frequency (BSF). Results: 67 children were identified. 30 (44.8%) started KD <2 years old, 37 (55.2%) started KD 2-4 years old. Among <2 years old group, 83.3% achieved 50% reduction in BSF and 36.7% achieved 90% reduction. Among 2-4 year old group, 62.2% achieved 50% reduction in BSF and 24.3% achieved 90% reduction. 38 children had a history of IS; 17 with IS at diet initiation and 21 with past history of IS. 41.2% of the spasms cohort achieved 90% reduction in BSF, compared to 23.8% of the post-spasms cohort. Conclusions: KD was more effective when started before age 2 years than 2-4 years, and more effective in children with IS than in children with past history of IS. A rapid protocol for KD initiation in young infants and children may improve long-term outcomes
An elongated ERO with R - K′ = 7.5 behind the cluster A851 at z=0.4 was found to lie at z = 1.5 both by the photometric redshift and by a cross correlation method of its H-band SED with local E/SO spectra. the luminosity profile is well represented by a seeing convolved exponential disk, and the lack of redshifted H-alpha emission indicates that it has a dynamically relaxed disk with an old stellar population. Gravitational lensing of the cluster is not strong enough to stretch the image and cannot convert the de Vaucouleurs law into an exponential law.
The region south of the reflection nebula NGC1333 in Perseus is an active star forming region including numerous Herbig-Haro objects and at least 5 protostar candidates with molecular outflows and far-infrared emission. It has been actively studied in various wave bands (e.g. Aspin et al 1994 and references therein). We observed this region with ASCA with the primary objective to detect X-rays from the protostars embedded deep in the molecular cloud.
In the present paper, we stress the importance of the magnetic field in the problem of acceleration and collimation of astrophysical jets, and discuss our proposed generic picture for such “central gravitator + jets + lobes” systems and inherent interpretations of the various observational characteristics of such systems: Mechanisms are proposed for (1) the enhanced liberation of gravitational energy at the central object, (2) the transfer of a part of the liberated energy along the large-scale magnetic field by large-amplitude, torsional Alfvén wave trains that form collimated jets (we call this a sweeping pinch process), (3) the dumping of the transferred energy at the end of the jets when they impinge on the denser region outside the border of the “cavity” from which the mass contracted to the central condensation (central gravitator + accretion disk, as well as the larger-scale condensation surrounding them), and (4) the formation of wiggled jets and lobes as helical kinks and the tucked-up magnetic field produced in the sweeping pinch process, respectively.
The VLBI Space Observatory Programme (VSOP) is the first dedicated Space-VLBI mission. We report here on the planning for a second generation mission which builds on and extends the successful collaborations established for the VSOP mission, and which aims to improve both resolution and sensitivity by a factor of ∼10.
About 40 hours of observing data received by the space radio telescope HALCA at L-band (1.6 GHz) were analyzed in order to investigate interference received by the space radio telescope. Autocorrelation spectra for this study were specially prepared at the DRAO S2-correlator with a 7.8125 kHz frequency resolution in each 16 MHz channel. It was found that during 20% of the observing time the interfering signal was above the tolerable level of 1% of total receiver noise in a 16 MHz channel. The major source of interference is identified with uplink communication from ships to geostationary satellites in the International Maritime Satellite service (INMARSAT). The frequency range allocated for INMARSAT is 1636.5–1645.0 MHz. INMARSAT uses four geostationary satellites, two of which are located above the Atlantic Ocean where the strongest interference was observed. To avoid this interference it is recommended to move the HALCA observing frequency range from the currently used 1634–1666 MHz to 1645–1677 MHz. A simple criterion is proposed to predict harmful interference from INMARSAT. This criterion may be used in scheduling of future HALCA observations at L-band.
We are using the VSOP space VLBI mission to observe a complete sample of Pearson-Readhead survey sources at 4.8 GHz to determine core brightness temperatures and pc-scale jet properties. To date we have imaged 27 of the 31 objects in our sample. Our preliminary results show that the majority of objects contain strong core components that remain unresolved on baselines of 30,000 km. The brightness temperatures of several cores significantly exceed 1012 K, which is indicative of highly relativistically beamed emission. We also find that core brightness temperature is correlated with intraday variability in compact AGNs.
The Mitaka correlator is an FX-type correlator with 10-station inputs, which is designed for space VLBI and will be used for VSOP mainly. We report here the capabilities of the correlator, the results of model comparisons and the preliminary results of fringe test between the satellite HALCA and Japanese ground telescopes.