3,427 research outputs found
Intensity of Vascular Streak Dieback in Different Cocoa Clones and Various Agro-climatic Conditions
Vascular streak dieback (VSD) is one of the main diseases on cocoa. This disease can produce a heavy damage in susceptible plants. Agro-climatic condition influences the VSD disease severity level. A study on the relationship between agro-climatic condition and VSD disease severity was conducted in eight locations which were selected based on difference in agro-climatic conditions including altitude, rainfall, number of wet, and dry months. Randomized complete block design was used consisting of eight agro-climatic conditions as treatments which consisted of 200 trees samples, and scored for VSD intensity. A study was also conducted on the response of cocoa clones with different level of resistance at different altitude at Kendeng Lembu, Jatirono, Sungai Lembu, Banjarsari, and Sumber Asin Plantations. A split plot design was applied consisting of two factors. The first factor was location including Pager Gunung (highland) and Besaran (lowland). The second factor was clone resistance with two levels: PA 191 (resistant) and BL 703 (susceptible). VSD scores and stomatal characteristics (stomata number, stomata diameter, and stomata aperture) were determined. The results of experiment showed that VSD scoring differed significantly between the eight agro-climatic conditions. The highest VSD score occurred in the lowland (Gereng Rejo, Banjarsari Plantation, 38 m asl.), where the average annual rainfall was 2161 mm, with five dry months. Cocoa trees in Sumber Asin (580 m asl.), with the average annual rainfall of 2302 mm and 8.5 wet months/3.5 dry months were mostly free of VSD disease. Altitude was positively correlated with rainfall, and negatively correlated with VSD severity. Number of wet months was negatively correlated with VSD severity. Conversely, number of dry months was positively correlated with VSD. The result indicated that genotype, environment, or their interaction did not significantly affect number and aperture of stomata. Although stomatal diameter was significantly affected by environment, genotypes or their interaction with environment did not influence this character
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 s–1. 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 J1748–3009, the millisecond pulsar with the highest known DM (420 pc cm–3). We also discovered PSR J1840–0643, which is in a binary system with an orbital period of 937 days, the fourth largest known. The new pulsar J1750–2536 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
Enumerating Abelian Returns to Prefixes of Sturmian Words
We follow the works of Puzynina and Zamboni, and Rigo et al. on abelian
returns in Sturmian words. We determine the cardinality of the set
of abelian returns of all prefixes of a Sturmian word in
terms of the coefficients of the continued fraction of the slope, dependingly
on the intercept. We provide a simple algorithm for finding the set
and we determine it for the characteristic Sturmian words.Comment: 19page
Transcatheter closure of a large patent ductus arteriosus with the clamshell septal umbrella
AbstractIn 14 patients undergoing transcatheter closure of a large (>4 mm diameter) patent ductus arteriosus, occlusion was attempted with use of the Bard Clamshell septal umbrella. Patient age ranged from 0.7 to 30.4 years. Isolated patent ductus arteriosus was present in 11 patients; 3 had additional congenital heart lesions. Moderate or severe pulmonary hypertension was present in four patients. The diameter of the patent ductus arteriosus ranged from 4.5 to 14 mm, as determined by contrast injection through an 11F sheath or by balloon sizing; it appeared larger by this method than by the standard angiographic method.All 14 patent ductus arteriosi were successfully closed. Prior embolization of a Rashkind umbrella was the reason for using a Clamshell device in three patients; one additional embolization of a Clamshell device occurred. All errant devices were retrieved at cardiac catheterization, without associated hemodynamic instability. No other complications occurred. Among the 14 patients, 11 had complete ductal closure by Doppler color flow mapping at last follow-up and 3 had trivial residual Row. All four patients having associated complex lesions or pulmonary hypertension, or both, had symptomatic improvement after the procedure, although one child (with Shone's anomaly) died 3 months later.The Clamshell device provides stable and effective closure of a large patent ductus arteriosus, and allows transcatheter closure to be offered to some patients who were previously considered unsuitable for this procedure
Infrared Observations of Hot Gas and Cold Ice toward the Low Mass Protostar Elias 29
We have obtained the full 1-200 um spectrum of the low luminosity (36 Lsun)
Class I protostar Elias 29 in the Rho Ophiuchi molecular cloud. It provides a
unique opportunity to study the origin and evolution of interstellar ice and
the interrelationship of interstellar ice and hot core gases around low mass
protostars. We see abundant hot CO and H2O gas, as well as the absorption bands
of CO, CO2, H2O and ``6.85 um'' ices. We compare the abundances and physical
conditions of the gas and ices toward Elias 29 with the conditions around
several well studied luminous, high mass protostars. The high gas temperature
and gas/solid ratios resemble those of relatively evolved high mass objects
(e.g. GL 2591). However, none of the ice band profiles shows evidence for
significant thermal processing, and in this respect Elias 29 resembles the
least evolved luminous protostars, such as NGC 7538 : IRS9. Thus we conclude
that the heating of the envelope of the low mass object Elias 29 is
qualitatively different from that of high mass protostars. This is possibly
related to a different density gradient of the envelope or shielding of the
ices in a circumstellar disk. This result is important for our understanding of
the evolution of interstellar ices, and their relation to cometary ices.Comment: 18 pages and 14 figures, accepted for publication in A&
Polarization studies of Rotating Radio Transients
We study the polarization properties of 22 known rotating radio transients
(RRATs) with the 64-m Parkes radio telescope and present the Faraday rotation
measures (RMs) for the 17 with linearly polarized flux exceeding the off-pulse
noise by 3. Each RM was estimated using a brute-force search over trial
RMs that spanned the maximum measurable range (in steps of 1 ), followed by an
iterative refinement algorithm. The measured RRAT RMs are in the range |RM|
to rad m with an average linear polarization
fraction of per cent. Individual single pulses are observed to be up
to 100 per cent linearly polarized. The RMs of the RRATs and the corresponding
inferred average magnetic fields (parallel to the line-of-sight and weighted by
the free electron density) are observed to be consistent with the Galactic
plane pulsar population. Faraday rotation analyses are typically performed on
accumulated pulsar data, for which hundreds to thousands of pulses have been
integrated, rather than on individual pulses. Therefore, we verified the
iterative refinement algorithm by performing Monte Carlo simulations of
artificial single pulses over a wide range of S/N and RM. At and above a S/N of
17 in linearly polarized flux, the iterative refinement recovers the simulated
RM value 100 per cent of the time with a typical mean uncertainty of
rad m. The method described and validated here has also been
successfully used to determine reliable RMs of several fast radio bursts (FRBs)
discovered at Parkes.Comment: Submitted to MNRAS, 10 pages, 6 figure
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