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The recession of mountain glaciers worldwide is increasing global sea level and, in many regions, human activities will have to adapt to changes in surface hydrology. Thus, it is important to provide up-to-date analyses of glacier change and the factors modulating their response to climate warming. Here we report changes in the extent of >120 glaciers on the Lyngen Peninsula, northern Norway, where glacier runoff is utilised for hydropower and where glacial lake outburst floods have occurred. Glaciers covered at least 114 km2 in 1953 and we compare this inventory with those from 1988, 2001 and a new one from 2014, and previously-dated Little Ice Age (LIA) limits. Results show a steady reduction in area (~0.3% a−1) between their LIA maximum (~1915) and 1988, consistent with increasing summer air temperatures, but recession paused between 1988 and 2001, coinciding with increased winter precipitation. Air temperatures increased 0.5°C per decade from the 1990s and the rate of recession accelerated to ~1% a−1 between 2001 and 2014 when glacier area totalled ~95.7 km2. Small glaciers (<0.05 km2) with low maximum elevations (<1400 m) experienced the largest percentage losses and, if warming continues, several glaciers may disappear within the next two decades.
We report on new pulsars discovered in Arecibo drift-scan datA. Processing of 2200 deg2 of data has resulted in the detection of 41 known and 12 new pulsars. New pulsars include two millisecond pulsars, one solitary and one binary recycled pulsar, and one pulsar with very unusual pulse profile morphology and complex drifting subpulse behavior.
This article proposes an assessment of the ingestion doses potentially received by people
living in the Japanese areas most severely affected by the radioactive deposits due to the
Fukushima nuclear accident. The assessment distinguishes two consecutive periods: the
first 2 months (March 15th to May 15th 2011) and the rest of the year 2011, according to
the two main foodstuff contamination periods identified (Renaud et al.,
2013). On the basis of the worst-case hypothesis that can reasonably be made, the
estimated doses are much lower than they might have been in other circumstances, on
account of generally moderate levels of contamination for most foods, early evacuation of
the most severely affected areas and the consumption bans ordered by the Japanese
authorities. Thus, a single ingestion of 100 g of leafy vegetables in the early days by a
one-year-old child living in non-evacuated localities near Iitate and Kawamata could have
led to an equivalent dose to the thyroid of about 25 mSv; and to a thyroid dose of about
140 mSv for the rather unrealistic scenario of a daily consumption. Because of the rapid
decrease in the contamination of vegetables and a much weaker contamination of other
crops, and thanks to measures taken by the authorities (prohibition of consumption, use of
certain fodder, etc.), the ingestion doses potentially received during the remainder of
the year 2011 are estimated to be below 1 mSv. In the event that sales limits would have
been ignored, only repeated consumption of mushrooms would have led to doses above that
level. Even with the worst-case hypotheses, the doses potentially caused by ingestion are
much lower than those resulting from outdoor exposure to radioactive deposits:
approximately several millisieverts in a year for the population living in the
non-evacuated localities near Iitate and Kawamata.
During and after the Fukushima accident, the IRSN collected and interpreted the results
of radiological measurements performed on foodstuffs of terrestrial origin published by
Japan's Ministry of Health between mid-March 2011 and July 2012. Analysis of the findings
shows that the accident's date, livestock-rearing practices and the deposits'
characteristics had a decisive influence. The fact that radioactive fallout occurred very
early in the growing and breeding season largely explains the moderate contamination of
most foodstuffs of terrestrial origin, notably in the areas with the largest deposits. In
the case of dairy products and meat, feeding imported fodder to livestock in stables, a
common practice in Japan, compounded the calendar effect. Measurements published in Japan
have also borne out the particular sensitivity of mushrooms, including cultivated species,
The first direct detection of gravitational waves may be made through observations of pulsars. The principal aim of pulsar timing-array projects being carried out worldwide is to detect ultra-low frequency gravitational waves (f ∼ 10−9–10−8 Hz). Such waves are expected to be caused by coalescing supermassive binary black holes in the cores of merged galaxies. It is also possible that a detectable signal could have been produced in the inflationary era or by cosmic strings. In this paper, we review the current status of the Parkes Pulsar Timing Array project (the only such project in the Southern hemisphere) and compare the pulsar timing technique with other forms of gravitational-wave detection such as ground- and space-based interferometer systems.
The PULSE@Parkes project has been designed to monitor the rotation of radio pulsars over time spans of days to years. The observations are obtained using the Parkes 64-m and 12-m radio telescopes by Australian and international high school students. These students learn the basis of radio astronomy and undertake small projects with their observations. The data are fully calibrated and obtained with the state-of-the-art pulsar hardware available at Parkes. The final data sets are archived and are currently being used to carry out studies of 1) pulsar glitches, 2) timing noise, 3) pulse profile stability over long time scales and 4) the extreme nulling phenomenon. The data are also included in other projects such as gamma-ray observatory support and for the Parkes Pulsar Timing Array project. In this paper we describe the current status of the project and present the first scientific results from the Parkes 12-m radio telescope. We emphasise that this project offers a straightforward means to enthuse high school students and the general public about radio astronomy while obtaining scientifically valuable data sets.
A ‘pulsar timing array’ (PTA), in which observations of a large sample of pulsars spread across the celestial sphere are combined, allows investigation of ‘global’ phenomena such as a background of gravitational waves or instabilities in atomic timescales that produce correlated timing residuals in the pulsars of the array. The Parkes Pulsar Timing Array (PPTA) is an implementation of the PTA concept based on observations with the Parkes 64-m radio telescope. A sample of 20 ms pulsars is being observed at three radio-frequency bands, 50 cm (~700 MHz), 20 cm (~1400 MHz), and 10 cm (~3100 MHz), with observations at intervals of two to three weeks. Regular observations commenced in early 2005. This paper describes the systems used for the PPTA observations and data processing, including calibration and timing analysis. The strategy behind the choice of pulsars, observing parameters, and analysis methods is discussed. Results are presented for PPTA data in the three bands taken between 2005 March and 2011 March. For 10 of the 20 pulsars, rms timing residuals are less than 1 μs for the best band after fitting for pulse frequency and its first time derivative. Significant ‘red’ timing noise is detected in about half of the sample. We discuss the implications of these results on future projects including the International Pulsar Timing Array and a PTA based on the Square Kilometre Array. We also present an ‘extended PPTA’ data set that combines PPTA data with earlier Parkes timing data for these pulsars.
We report here on two years of timing of 168 pulsars using the Parkes radio telescope. The vast majority of these pulsars have spin-down luminosities in excess of 1034 erg s−1 and are prime target candidates to be detected in gamma-rays by the Fermi Gamma-Ray Space Telescope. We provide the ephemerides for the ten pulsars being timed at Parkes which have been detected by Fermi in its first year of operation. These ephemerides, in conjunction with the publicly available photonlist, can be used to generate gamma-ray profiles from the Fermi archive. We will make the ephemerides of any pulsars of interest available to the community upon request. In addition to the timing ephemerides, we present the parameters for 14 glitches which have occurred in 13 pulsars, seven of which have no previously known glitch history.The Parkes timing programme, in conjunction with Fermi observations, is expected to continue for at least the next four years.