226 research outputs found
Einstein@Home Discovery of 24 Pulsars in the Parkes Multi-Beam Pulsar Survey
We have conducted a new search for radio pulsars in compact binary systems in the Parkes multi-beam pulsar survey (PMPS) data, employing novel methods to remove the Doppler modulation from binary motion. This has yielded unparalleled sensitivity to pulsars in compact binaries. The required computation time of 17, 000 CPU core years was provided by the distributed volunteer computing project Einstein@Home, which has a sustained computing power of about 1 PFlop sâ1. We discovered 24 new pulsars in our search, 18 of which were isolated pulsars, and 6 were members of binary systems. Despite the wide filterbank channels and relatively slow sampling time of the PMPS data, we found pulsars with very large ratios of dispersion measure (DM) to spin period. Among those is PSR J1748â3009, the millisecond pulsar with the highest known DM (420 pc cmâ3). We also discovered PSR J1840â0643, which is in a binary system with an orbital period of 937 days, the fourth largest known. The new pulsar J1750â2536 likely belongs to the rare class of intermediate-mass binary pulsars. Three of the isolated pulsars show long-term nulling or intermittency in their emission, further increasing this growing family. Our discoveries demonstrate the value of distributed volunteer computing for data-driven astronomy and the importance of applying new analysis methods to extensively searched data
The PALFA Survey: Going to great depths to find radio pulsars
The on-going PALFA survey is searching the Galactic plane (|b| < 5 deg., 32 <
l < 77 deg. and 168 < l < 214 deg.) for radio pulsars at 1.4 GHz using ALFA,
the 7-beam receiver installed at the Arecibo Observatory. By the end of August
2012, the PALFA survey has discovered 100 pulsars, including 17 millisecond
pulsars (P < 30 ms). Many of these discoveries are among the pulsars with the
largest DM/P ratios, proving that the PALFA survey is capable of probing the
Galactic plane for millisecond pulsars to a much greater depth than any
previous survey. This is due to the survey's high sensitivity, relatively high
observing frequency, and its high time and frequency resolution. Recently the
rate of discoveries has increased, due to a new more sensitive spectrometer,
two updated complementary search pipelines, the development of online
collaborative tools, and access to new computing resources. Looking forward,
focus has shifted to the application of artificial intelligence systems to
identify pulsar-like candidates, and the development of an improved
full-resolution pipeline incorporating more sophisticated radio interference
rejection. The new pipeline will be used in a complete second analysis of data
already taken, and will be applied to future survey observations. An overview
of recent developments, and highlights of exciting discoveries will be
presented.Comment: Proceedings of IAUS 291 "Neutron Stars and Pulsars: Challenges and
Opportunities after 80 years", J. van Leeuwen (ed.); 6 pages, 4 figure
Fast Radio Burst Discovered in the Arecibo Pulsar ALFA Survey
Recent work has exploited pulsar survey data to identify temporally isolated,
millisecond-duration radio bursts with large dispersion measures (DMs). These
bursts have been interpreted as arising from a population of extragalactic
sources, in which case they would provide unprecedented opportunities for
probing the intergalactic medium; they may also be linked to new source
classes. Until now, however, all so-called fast radio bursts (FRBs) have been
detected with the Parkes radio telescope and its 13-beam receiver, casting some
concern about the astrophysical nature of these signals. Here we present FRB
121102, the first FRB discovery from a geographic location other than Parkes.
FRB 121102 was found in the Galactic anti-center region in the 1.4-GHz Pulsar
ALFA survey with the Arecibo Observatory with a DM = 557.4 3 pc
cm, pulse width of ms, and no evidence of interstellar
scattering. The observed delay of the signal arrival time with frequency agrees
precisely with the expectation of dispersion through an ionized medium. Despite
its low Galactic latitude (), the burst has three times the
maximum Galactic DM expected along this particular line-of-sight, suggesting an
extragalactic origin. A peculiar aspect of the signal is an inverted spectrum;
we interpret this as a consequence of being detected in a sidelobe of the ALFA
receiver. FRB 121102's brightness, duration, and the inferred event rate are
all consistent with the properties of the previously detected Parkes bursts.Comment: 9 pages, 3 figures, submitted to Ap
On detecting millisecond pulsars at the galactic center
The lack of detected pulsars at the Galactic Center (GC) region is a long-standing mystery. We argue that the high stellar density in the central parsec around the GC is likely to result in a pulsar population dominated by millisecond pulsars (MSPs), similar to the situation in globular cluster environments. Earlier GC pulsar searches have been largely insensitive to such an MSP population, accounting for the lack of pulsar detections. We estimate the best search frequency for such an MSP population with present and upcoming broad-band radio telescopes for two possible scattering scenarios, the âweak-scatteringâ case suggested by the recent detection of a magnetar close to the GC, and the âstrong-scatteringâ case, with the scattering screen located close to the GC. The optimal search frequencies are â 8 GHz ( weak-scattering ) and â 25 GHz ( strong-scattering ) , for pulsars with periods 1 â 20 ms, assuming that GC pulsars have a luminosity distribution similar to that those in the rest of the Milky Way. We find that 10 â 30 hr integrations with the Very Large Array and the Green Bank Telescope would be sufficient to detect MSPs at the GC distance in the weak-scattering case. However, if the strong-scattering case is indeed applicable to the GC, observations with the full Square Kilometre Array would be needed to detect the putative MSP population
Assessment of the risk to Norwegian biodiversity from import and keeping of American bison, European bison, domesticated water buffalo and domesticated yak. Scientific Opinion of the panel on Alien Organisms and Trade in Endangered Species (CITES) of the Norwegian Scientific Committee for Food and Environment
publishedVersio
The Establishment of Genetically Engineered Canola Populations in the U.S.
Concerns regarding the commercial release of genetically engineered (GE) crops include naturalization, introgression to sexually compatible relatives and the transfer of beneficial traits to native and weedy species through hybridization. To date there have been few documented reports of escape leading some researchers to question the environmental risks of biotech products. In this study we conducted a systematic roadside survey of canola (Brassica napus) populations growing outside of cultivation in North Dakota, USA, the dominant canola growing region in the U.S. We document the presence of two escaped, transgenic genotypes, as well as non-GE canola, and provide evidence of novel combinations of transgenic forms in the wild. Our results demonstrate that feral populations are large and widespread. Moreover, flowering times of escaped populations, as well as the fertile condition of the majority of collections suggest that these populations are established and persistent outside of cultivation
Einstein@Home Discovery of a PALFA Millisecond Pulsar in an Eccentric Binary Orbit
We report the discovery of the millisecond pulsar (MSP) PSR J1950+2414 (P = 4.3 ms) in a binary system with an eccentric (e = 0.08) 22 day orbit in Pulsar Arecibo L-band Feed Array survey observations with the Arecibo telescope. Its companion star has a median mass of 0.3M(circle dot) and is most likely a white dwarf (WD). Fully recycled MSPs like this one are thought to be old neutron stars spun-up by mass transfer from a companion star. This process should circularize the orbit, as is observed for the vast majority of binary MSPs, which predominantly have orbital eccentricities e <0.001. However, four recently discovered binary MSPs have orbits with 0. 027 <e <0.44; PSR J1950+2414 is the fifth such system to be discovered. The upper limits for its intrinsic spin period derivative and inferred surface magnetic field strength are comparable to those of the general MSP population. The large eccentricities are incompatible with the predictions of the standard recycling scenario: something unusual happened during their evolution. Proposed scenarios are (a) initial evolution of the pulsar in a triple system which became dynamically unstable, (b) origin in an exchange encounter in an environment with high stellar density, (c) rotationally delayed accretion-induced collapse of a super-Chandrasekhar WD, and (d) dynamical interaction of the binary with a circumbinary disk. We compare the properties of all five known eccentric MSPs with the predictions of these formation channels. Future measurements of the masses and proper motion might allow us to firmly exclude some of the proposed formation scenarios
The release of common pheasants and grey partridges for pointing dog training- consequences for biodiversity, animal welfare and health. Scientific Opinion of the Panel on Biodiversity of the Norwegian Scientific Committee for Food and Environment
Bakgrunn Siden sent pü 1800-tallet har det blitt satt ut et ukjent antall tamme fasaner og rapphøns i norsk natur. Disse fuglene brukes til jakttrening av stüende fuglehunder. Import, hold og utsetting av fasaner og rapphøns har i liten grad vÌrt regulert og det er heller ikke utredet hvilke konsekvenser som import, hold og utsetting og jakttrening vil kunne ha for biologisk mangfold, dyrehelse og dyrevelferd. Miljødirektoratet og Mattilsynet har i felleskap bedt VKM om ü utarbeide en vitenskapelig vurdering av mulige konsekvenser av utsetting av fasan og rapphøns pü biologisk mangfold, dyrehelse og dyrevelferd. VKM ble ogsü bedt om ü foreslü eventuelle risikoreduserende tiltak for biologisk mangfold og dyrevelferd. Metoder VKM opprettet en prosjektgruppe med ekspertise innenfor blant annet fugleøkologi, landskapsøkologi, populasjonsbiologi, viltmedisin og dyrevelferd. Gruppen utførte systematiske litteratursøk, undersøkte resultatene fra søkene og supplerte med andre relevante studier der det var nødvendig. I mangel av studier fra norske forhold brukte VKM studier fra andre land som setter ut fasaner og rapphøns (og i noen tilfeller andre arter av fuglevilt) som referanse. VKM undersøkte observasjonsdata for fasaner og rapphøns i Norge for perioden 2000 til 2022. I vurderingen av de ulike aspektene som vil kunne püvirkes av utsettingen, la VKM til grunn en ürlig utsetting av noen fü tusen fugler i Norge. Høyere antall og tetthet av fugler vil øke sannsynligheten for negative effekter og alvorlighetsgraden av konsekvensene. VKM vurderte effekten som utsatte fasaner og rapphøns har pü konkurranse med norske fugler,, krysning med beslektede arter, sykdomsoverføring, effekter pü flora (herbivori), og fauna (predasjon). I tillegg ble indirekte effekter gjennom interaksjon med andre arter vurtdert. VKM vurderte ogsü effekt pü biologisk mangfold i et 50-ürs perspektiv. I tillegg diskuterte VKM hvordan fuglenes velferd vil kunne püvirkes av hold, transport, utsetting, og eksponering for jakthunder. VKM lister ogsü opp relevante sykdommer og vurderer den potensielle effekten av disse pü dyrehelse under hold, transport og utsetting. For vurdering av aspekter relatert til import og dyrehelse, la VKM til grunn at fuglene importeres fra Sverige. Resultater og konklusjoner VKMs vurderinger viste at utsetting av fasaner og rapphøns i norsk natur medfører risiko for biologisk mangfold, dyrehelse og dyrevelferd. Risiko for økt konkurranse om mat vinterstid med fugler som har lignende økologisk nisje som fasaner og rapphøns, er lav pü nasjonal skala og moderat pü lokal skala. Det gjelder spesielt gulspurv, Emberiza citronella. Denne arten er klassifisert som sürbar pü den nasjonale rødlisten grunnet økende nedgang i bestanden, som igjen er forürsaket av redusert tilgjengelighet av mat om vinteren. Det er videre moderat risiko for predasjon pü invertebrater (virvelløse dyr) og negative effekter pü flora.The release of common pheasants and grey partridges for pointing dog training- consequences for biodiversity, animal welfare and health. Scientific Opinion of the Panel on Biodiversity of the Norwegian Scientific Committee for Food and EnvironmentpublishedVersio
Timing of Five PALFA-Discovered Millisecond Pulsars
We report the discovery and timing results for five millisecond pulsars (MSPs) from the Arecibo PALFA survey: PSRs J1906+0055, J1914+0659, J1933+1726, J1938+2516, and J1957+2516. Timing observations of the five pulsars were conducted with the Arecibo and Lovell telescopes for time spans ranging from 1.5 to 3.3 years. All of the MSPs except one (PSR J1914+0659) are in binary systems with low eccentricities. PSR J1957+2516 is likely a redback pulsar, with a companion and possible eclipses that last ~10% of the orbit. The position of PSR J1957+2516 is also coincident with a near-infrared source. All five MSPs are distant ( kpc) as determined from their dispersion measures, and none of them show evidence of Îł-ray pulsations in a fold of Fermi Gamma-Ray Space Telescope data. These five MSPs bring the total number of MSPs discovered by the PALFA survey to 26 and further demonstrate the power of this survey in finding distant, highly dispersed MSPs deep in the Galactic plane
The release of common pheasants and grey partridges for pointing dog training- consequences for biodiversity, animal welfare and health. Scientific Opinion of the Panel on Biodiversity of the Norwegian Scientific Committee for Food and Environment
Source at https://vkm.no/.Bakgrunn Siden sent pü 1800-tallet har det blitt satt ut et ukjent antall tamme fasaner og rapphøns i norsk natur. Disse fuglene brukes til jakttrening av stüende fuglehunder. Import, hold og utsetting av fasaner og rapphøns har i liten grad vÌrt regulert og det er heller ikke utredet hvilke konsekvenser som import, hold og utsetting og jakttrening vil kunne ha for biologisk mangfold, dyrehelse og dyrevelferd. Miljødirektoratet og Mattilsynet har i felleskap bedt VKM om ü utarbeide en vitenskapelig vurdering av mulige konsekvenser av utsetting av fasan og rapphøns pü biologisk mangfold, dyrehelse og dyrevelferd. VKM ble ogsü bedt om ü foreslü eventuelle risikoreduserende tiltak for biologisk mangfold og dyrevelferd. Metoder VKM opprettet en prosjektgruppe med ekspertise innenfor blant annet fugleøkologi, landskapsøkologi, populasjonsbiologi, viltmedisin og dyrevelferd. Gruppen utførte systematiske litteratursøk, undersøkte resultatene fra søkene og supplerte med andre relevante studier der det var nødvendig. I mangel av studier fra norske forhold brukte VKM studier fra andre land som setter ut fasaner og rapphøns (og i noen tilfeller andre arter av fuglevilt) som referanse. VKM undersøkte observasjonsdata for fasaner og rapphøns i Norge for perioden 2000 til 2022. I vurderingen av de ulike aspektene som vil kunne püvirkes av utsettingen, la VKM til grunn en ürlig utsetting av noen fü tusen fugler i Norge. Høyere antall og tetthet av fugler vil øke sannsynligheten for negative effekter og alvorlighetsgraden av konsekvensene. VKM vurderte effekten som utsatte fasaner og rapphøns har pü konkurranse med norske fugler,, krysning med beslektede arter, sykdomsoverføring, effekter pü flora (herbivori), og fauna (predasjon). I tillegg ble indirekte effekter gjennom interaksjon med andre arter vurtdert. VKM vurderte ogsü effekt pü biologisk mangfold i et 50-ürs perspektiv. I tillegg diskuterte VKM hvordan fuglenes velferd vil kunne püvirkes av hold, transport, utsetting, og eksponering for jakthunder. VKM lister ogsü opp relevante sykdommer og vurderer den potensielle effekten av disse pü dyrehelse under hold, transport og utsetting. For vurdering av aspekter relatert til import og dyrehelse, la VKM til grunn at fuglene importeres fra Sverige. Resultater og konklusjoner VKMs vurderinger viste at utsetting av fasaner og rapphøns i norsk natur medfører risiko for biologisk mangfold, dyrehelse og dyrevelferd. Risiko for økt konkurranse om mat vinterstid med fugler som har lignende økologisk nisje som fasaner og rapphøns, er lav pü nasjonal skala og moderat pü lokal skala. Det gjelder spesielt gulspurv, Emberiza citronella. Denne arten er klassifisert som sürbar pü den nasjonale rødlisten grunnet økende nedgang i bestanden, som igjen er forürsaket av redusert tilgjengelighet av mat om vinteren. Det er videre moderat risiko for predasjon pü invertebrater (virvelløse dyr) og negative effekter pü flora.The release of common pheasants and grey partridges for pointing dog training- consequences for biodiversity, animal welfare and health. Scientific Opinion of the Panel on Biodiversity of the Norwegian Scientific Committee for Food and EnvironmentpublishedVersio
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