42,868 research outputs found
The High Time Resolution Universe surveys for pulsars and fast transients
The High Time Resolution Universe survey for pulsars and transients is the
first truly all-sky pulsar survey, taking place at the Parkes Radio Telescope
in Australia and the Effelsberg Radio Telescope in Germany. Utilising multibeam
receivers with custom built all-digital recorders the survey targets the
fastest millisecond pulsars and radio transients on timescales of 64 us to a
few seconds. The new multibeam digital filter-bank system at has a factor of
eight improvement in frequency resolution over previous Parkes multibeam
surveys, allowing us to probe further into the Galactic plane for short
duration signals. The survey is split into low, mid and high Galactic latitude
regions. The mid-latitude portion of the southern hemisphere survey is now
completed, discovering 107 previously unknown pulsars, including 26 millisecond
pulsars. To date, the total number of discoveries in the combined survey is 135
and 29 MSPs. These discoveries include the first magnetar to be discovered by
it's radio emission, unusual low-mass binaries, gamma-ray pulsars and pulsars
suitable for pulsar timing array experiments.Comment: Proceedings of IAUS 291 "Neutron Stars and Pulsars: Challenges and
Opportunities after 80 years"; J. van Leeuwen (ed.); 6 pages, 2 figure
The part-frequency matrices of a partition
A new combinatorial object is introduced, the part-frequency matrix sequence
of a partition, which is elementary to describe and is naturally motivated by
Glaisher's bijection. We prove results that suggest surprising usefulness for
such a simple tool, including the existence of a related statistic that
realizes every possible Ramanujan-type congruence for the partition function.
To further exhibit its research utility, we give an easy generalization of a
theorem of Andrews, Dixit and Yee on the mock theta functions. Throughout, we
state a number of observations and questions that can motivate an array of
investigations.Comment: Presented at the Kliakhandler Conference 2015, Algebraic
Combinatorics and Applications, at Michigan Technological University. To
appear in the Proceeding
Proof of a conjectured q,t-Schr\"{o}der identity
A conjecture of Chunwei Song on a limiting case of the q,t-Schr\"{o}der
theorem is proved combinatorially. The proof matches pairs of tableaux to
Catalan words in a manner that preserves differences in the maj statistic.Comment: 8 pages; v2 corrects presentation error in example and notation
(substance of proof unchanged
Partitions into a small number of part sizes
We study , the number of partitions of into part sizes, and
find numerous arithmetic progressions where and take on values
divisible by 2 and 4. Expanding earlier work, we show for (A,B) = (36,30), (72,42), (252,114), (196,70), and likely many
other progressions for which our method should easily generalize. Of some
independent interest, we prove that the overpartition function in the first three progressions (the fourth is known), and
thereby show that in each of these progressions
as well, and discuss the relationship between these congruences in more
generality. We end with open questions in this area.Comment: 11 pages; v2, small correction to proof of Theorem 7; v3, clean up
some explanations, acknowledge recent results from Xinhua Xiong on
overpartitions mod 16; v4, final journal version to appear International
Journal of Number Theory (Feb. 2017
Installation and Use of Pulsar Search Software
Searching for radio pulsars typically requires a bespoke software pipeline to
efficiently make new discoveries. In this paper we describe the search process,
provide a tool for installing pulsar software, and give an example of a pulsar
search.Comment: Tutorial on tempo2 presented at the Beijing pulsar conference during
2011. To appear in "Astronomical Research and Technology" Vol.9, No.3, page
21
Automatic Pet Door and Magnetic Field Activation
Automatic pet doors are sold commercially as a completely built unit on today’s market. A low-cost design has been created to allow more flexible placement and construction of a door. This door is unlocked upon detection of a magnetic field originating from the pet’s collar. The required activation signal has been carefully characterized to allow customization of the door and collar for a particular purpose. Detailed information on the operating circuit and sensor activation are provided. Results of how the door is constructed and operated, as well as personalization, are presented
A Bijection for Partitions with Initial Repetitions
A theorem of Andrews equates partitions in which no part is repeated more
than 2k-1 times to partitions in which, if j appears at least k times, all
parts less than j also do so. This paper proves the theorem bijectively, with
some of the generalizations that usually arise from such proofs.Comment: 5 page
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