7,272 research outputs found
New RR Lyrae variables in binary systems
Despite their importance, very few RR Lyrae (RRL) stars have been known to
reside in binary systems. We report on a search for binary RRL in the OGLE-III
Galactic bulge data. Our approach consists in the search for evidence of the
light-travel time effect in so-called observed minus calculated ()
diagrams. Analysis of 1952 well-observed fundamental-mode RRL in the OGLE-III
data revealed an initial sample of 29 candidates. We used the recently released
OGLE-IV data to extend the baselines up to 17 years, leading to a final sample
of 12 firm binary candidates. We provide diagrams and binary parameters
for this final sample, and also discuss the properties of 8 additional
candidate binaries whose parameters cannot be firmly determined at present. We
also estimate that per cent of the RRL reside in binary systems.Comment: MNRAS Letters, in pres
On conjectures and problems of Ruzsa concerning difference graphs of S-units
Given a finite nonempty set of primes S, we build a graph with
vertex set by connecting x and y if the prime divisors of both the
numerator and denominator of x-y are from S. In this paper we resolve two
conjectures posed by Ruzsa concerning the possible sizes of induced
nondegenerate cycles of , and also a problem of Ruzsa concerning
the existence of subgraphs of which are not induced subgraphs.Comment: 15 page
The effect of fertilizers on different wine grape varieties in model container trials
Nutrient supply trials were carried out in model container trials with sandy soils adjusted to low and high nutrient levels (P, K, Mg) for 16 varieties with 5 replications as determined from the averages of years and varieties. The utilization of high nutrient supply in the soil can be summed up as follows: Analysis data revealed an increase of P in the leaf and wood but there was no change in the grape. Potassium level increased in the leaf and wood but remained unchanged in the grape. Magnesium level increased in the leaf and wood and also in the grape.Of the production indices an increase was observed in the green mass, wood mass, grape number and grape weight but a decrease in mean grape weight and in the sugar and acid content of the must.Winterhardiness increased slightly.It was evident that some varieties differed considerably from the varietal mean in the evaluated parameters
The role of variety as genetic potential in nutrient utilization
A container model trial was set up on sandy soil with 5 replications to study the nutrient regime of 16 wine grape varieties in a 10 year program starting in 1982 at Kecskemet-Miklostelep in the Institute for Viticulture and Oenology. Leaf, fruit and wood analysis data and production parameters (fruit and wood weight, frost tolerance) were evaluated every year under identical cultural conditions. Interactions between years, varieties and nutrient elements (N, P, K, Ca, Mg, Zn, B, Fe, Mn) were discussed. Trials so far have proved the decisive role of variety characters fixed genetically on nutrient uptake and nutrient utilization at given nutrient supply
A heuristic quantum theory of the integer quantum Hall effect
Contrary to common belief, the current emitted by a contact embedded in a
two-dimensional electron gas (2DEG) is quantized in the presence of electric
and magnetic fields. This observation suggests a simple, clearly defined model
for the quantum current through a Hall device that does not invoke disorder or
interactions as the cause of the integer quantum Hall effect (QHE), but is
based on a proper quantization of the classical electron drift motion. The
theory yields a quantitative description of the breakdown of the QHE at high
current densities that is in agreement with experimental data. Furthermore,
several of its key points are in line with recent findings of experiments that
address the dependency of the QHE on the 2DEG bias voltage, results that are
not easily explained within the framework of conventional QHE models.Comment: 20 pages, 6 figure
The VVV Survey reveals classical Cepheids tracing a young and thin stellar disk across the Galaxy's bulge
Solid insight into the physics of the inner Milky Way is key to understanding
our Galaxy's evolution, but extreme dust obscuration has historically hindered
efforts to map the area along the Galactic mid-plane. New comprehensive
near-infrared time-series photometry from the VVV Survey has revealed 35
classical Cepheids, tracing a previously unobserved component of the inner
Galaxy, namely a ubiquitous inner thin disk of young stars along the Galactic
mid-plane, traversing across the bulge. The discovered period (age) spread of
these classical Cepheids implies a continuous supply of newly formed stars in
the central region of the Galaxy over the last 100 million years.Comment: Accepted for publication in The Astrophysical Journal Letters.
Near-IR finding charts of the Cepheids are available at the following URL:
http://www.astro.puc.cl/~idekany/pub/inner_disk_ceph_fc.pn
On the modulation of RR Lyrae stars in the globular cluster M3
A new, extended time-series photometry of M3 RR Lyrae stars has revealed that
four of the ten double-mode stars show large-amplitude Blazhko modulation of
both radial modes. The first, detailed analysis of the peculiar behavior of the
unique, Blazhko RRd stars is given. While the P1/P0 period ratio is normal, and
the overtone mode is dominant in the other RRd stars of the cluster, the period
ratio is anomalous and the fundamental mode has a larger (or similar) mean
amplitude than the overtone has in Blazhko RRd stars. The modulations of the
fundamental and overtone modes are synchronized only in one of the Blazhko RRd
stars. No evidence of any connection between the modulations of the modes in
the other three stars is found. The Blazhko modulation accounts, at least
partly, for the previously reported amplitude and period changes of these
stars. Contrary to the Blazhko statistics of RRab and RRd stars,
Blazhko modulation occurs only in 10 of the overtone variables in M3. Four
of the five Blazhko RRc stars are bright, evolved objects, and one has a
similar period and brightness as Blazhko RRd stars have. The regions of the
instability strip with high and low occurrence rate of the Blazhko modulation
overlap with the regions populated by first- and second-generation stars
according to theoretical and observational studies, raising up the possibility
that the Blazhko modulation occurs preferentially in first-generation RR Lyrae
stars.Comment: 6 pages, 4 figures, accepted for publication in ApJ
New skeletal tuberculosis cases in past populations from Western Hungary (Transdanubia)
The distribution, antiquity and epidemiology of tuberculosis (TB) have previously been studied in osteoarchaeological material in the eastern part of Hungary, mainly on the Great Plain. The purpose of this study is to map the occurrence of skeletal TB in different centuries in the western part of Hungary, Transdanubia, and to present new cases we have found. Palaeopathological analysis was carried out using macroscopic observation supported by radiographic and molecular methods. A large human osteoarchaeological sample (n = 5684) from Transdanubian archaeological sites ranging from the 2nd to the 18th centuries served as a source of material. Spinal TB was observed in seven individuals (in three specimens with Pott's disease two of which also had cold abscess) and hip TB was assumed in one case. The results of DNA for Mycobacterium tuberculosis were positive in seven of the eight cases identified by paleopathology, and negative in the assumed case of hip TB. However, the molecular results are consistent with highly fragmented DNA, which limited further analysis. Based on the present study and previously published cases, osteotuberculosis was found in Transdanubia mainly during the 9th–13th centuries. However, there are no signs of TB in many other 9th–13th century sites, even in those that lie geographically close to those where osteotuberculous cases were found. This may be due to a true absence of TB caused by the different living conditions, way of life, or origin of these populations. An alternative explanation is that TB was present in some individuals with no typical paleopathology, but that death occurred before skeletal morphological features could develop
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