157 research outputs found
Resistance to fungicides and streptomycin in Phytophthora parasitica : genetic determinism and use in hybrid determination
Progeny of #Phytophthora parasitica$ derived from the pairings between metalaxyl-resistant MET.1 (A2) carrying homozygous dominant resistance and S1 (A1) wild-type consisted of selfs from each parent and hybrids carrying heterozygous dominant resistance. Similar results were obtained when dimetomorph-resistant DT.1 (A1) carrying homozygous dominant resistance was paired with wild-type S2 (A2). Progeny from the pairing between homozygous Str resistant (A1) to streptomycin and A2 resistant to metalaxyl consisted of selfs and hybrids resistant to either streptomycin or metalaxyl but not both. These results suggest that streptomycin-resistance is cytoplasmic. Progeny from the pairing between homozygous metalaxyl-resistant MET.1 (A1) and homozygous Str (A2) resistant to streptomycin consisted of 28 selfs from A1, 32 selfs form A2, 2 hybrids resulting from the union of A1 oogonium with an A2 antheridium. Progeny from the pairing between homozygous dimetomorph and streptomycin-resistant DT.1 (A1) with wild-type S2 (A2) consisted of 22 selfs A1, 14 selfs A2 and 12 hybrids, two of them resulted from the union A2 oogonium with an A1 antheridium. (Résumé d'auteur
Dimethomorph and metalaxyl sensitivity in somatic hybrids of Phytophthora parasitica obtained by protoplast fusion
Protoplasts were successfully isolated from wild-type and mutant strains of #Phytophthora nicotianae var. #parasitica using Novozym 234. Putative somatic hybrids were recovered following protoplast fusions from the first time to dimethomorph resistant strain P 310 (Dim r) or metalaxyl P 26 (Met r) by selection on agar amended with dimethomorph and metalaxyl. Fusion products from this cross were resistant to dimethomorph and metalaxyl. Zoospore progeny from the fusion products retained this phenotype, suggesting that nuclear fusion had taken place. (Résumé d'auteur
Multi-seasonal systematic camera-trapping reveals fluctuating densities and high turnover rates of Carpathian lynx on the western edge of its native range
Camera-trapping and capture-recapture models are the most widely used tools for estimating densities of wild felids that have unique coat patterns, such as Eurasian lynx. However, studies dealing with this species are predominantly on a short-term basis and our knowledge of temporal trends and population persistence is still scarce. By using systematic camera-trapping and spatial capture-recapture models, we estimated lynx densities and evaluated density fluctuations, apparent survival, transition rate and individual's turnover during five consecutive seasons at three different sites situated in the Czech–Slovak–Polish borderland at the periphery of the Western Carpathians. Our density estimates vary between 0.26 and 1.85 lynx/100 km2 suitable habitat and represent the lowest and the highest lynx densities reported from the Carpathians. We recorded 1.5–4.1-fold changes in asynchronous fluctuated densities among all study sites and seasons. Furthermore, we detected high individual’s turnover (on average 46.3 ± 8.06% in all independent lynx and 37.6 ± 4.22% in adults) as well as low persistence of adults (only 3 out of 29 individuals detected in all seasons). The overall apparent survival rate was 0.63 ± 0.055 and overall transition rate between sites was 0.03 ± 0.019. Transition rate of males was significantly higher than in females, suggesting male-biased dispersal and female philopatry. Fluctuating densities and high turnover rates, in combination with documented lynx mortality, indicate that the population in our region faces several human-induced mortalities, such as poaching or lynx-vehicle collisions. These factors might restrict population growth and limit the dispersion of lynx to other subsequent areas, thus undermining the favourable conservation status of the Carpathian population. Moreover, our study demonstrates that long-term camera-trapping surveys are needed for evaluation of population trends and for reliable estimates of demographic parameters of wild territorial felids, and can be further used for establishing successful management and conservation measures
NectarCAM : a camera for the medium size telescopes of the Cherenkov Telescope Array
NectarCAM is a camera proposed for the medium-sized telescopes of the
Cherenkov Telescope Array (CTA) covering the central energy range of ~100 GeV
to ~30 TeV. It has a modular design and is based on the NECTAr chip, at the
heart of which is a GHz sampling Switched Capacitor Array and a 12-bit Analog
to Digital converter. The camera will be equipped with 265 7-photomultiplier
modules, covering a field of view of 8 degrees. Each module includes the
photomultiplier bases, high voltage supply, pre-amplifier, trigger, readout and
Ethernet transceiver. The recorded events last between a few nanoseconds and
tens of nanoseconds. The camera trigger will be flexible so as to minimize the
read-out dead-time of the NECTAr chips. NectarCAM is designed to sustain a data
rate of more than 4 kHz with less than 5\% dead time. The camera concept, the
design and tests of the various subcomponents and results of thermal and
electrical prototypes are presented. The design includes the mechanical
structure, cooling of the electronics, read-out, clock distribution, slow
control, data-acquisition, triggering, monitoring and services.Comment: In Proceedings of the 34th International Cosmic Ray Conference
(ICRC2015), The Hague, The Netherlands. All CTA contributions at
arXiv:1508.0589
The Cherenkov Telescope Array Large Size Telescope
The two arrays of the Very High Energy gamma-ray observatory Cherenkov
Telescope Array (CTA) will include four Large Size Telescopes (LSTs) each with
a 23 m diameter dish and 28 m focal distance. These telescopes will enable CTA
to achieve a low-energy threshold of 20 GeV, which is critical for important
studies in astrophysics, astroparticle physics and cosmology. This work
presents the key specifications and performance of the current LST design in
the light of the CTA scientific objectives.Comment: 4 pages, 5 figures, In Proceedings of the 33rd International Cosmic
Ray Conference (ICRC2013), Rio de Janeiro (Brazil). All CTA contributions at
arXiv:1307.223
An Assessment of the Effectiveness of High Definition Cameras as Remote Monitoring Tools for Dolphin Ecology Studies.
Research involving marine mammals often requires costly field programs. This paper assessed whether the benefits of using cameras outweighs the implications of having personnel performing marine mammal detection in the field. The efficacy of video and still cameras to detect Indo-Pacific bottlenose dolphins (Tursiops aduncus) in the Fremantle Harbour (Western Australia) was evaluated, with consideration on how environmental conditions affect detectability. The cameras were set on a tower in the Fremantle Port channel and videos were perused at 1.75 times the normal speed. Images from the cameras were used to estimate position of dolphins at the water’s surface. Dolphin detections ranged from 5.6 m to 463.3 m for the video camera, and from 10.8 m to 347.8 m for the still camera. Detection range showed to be satisfactory when compared to distances at which dolphins would be detected by field observers. The relative effect of environmental conditions on detectability was considered by fitting a Generalised Estimation Equations (GEEs) model with Beaufort, level of glare and their interactions as predictors and a temporal auto-correlation structure. The best fit model indicated level of glare had an effect, with more intense periods of glare corresponding to lower occurrences of observed dolphins. However this effect was not large (-0.264) and the parameter estimate was associated with a large standard error (0.113).The limited field of view was the main restraint in that cameras can be only applied to detections of animals observed rather than counts of individuals. However, the use of cameras was effective for long term monitoring of occurrence of dolphins, outweighing the costs and reducing the health and safety risks to field personal. This study showed that cameras could be effectively implemented onshore for research such as studying changes in habitat use in response to development and construction activities
Anonymous Traitor Tracing: How to Embed Arbitrary Information in a Key
In a traitor tracing scheme, each user is given a different decryption key. A content distributor can encrypt digital content using a public encryption key and each user in the system can decrypt it using her decryption key. Even if a coalition of users combines their decryption keys and constructs some ``pirate decoder\u27\u27 that is capable of decrypting the content, there is a public tracing algorithm that is guaranteed to recover the identity of at least one of the users in the coalition given black-box access to such decoder.
In prior solutions, the users are indexed by numbers and the tracing algorithm recovers the index of a user in a coalition. Such solutions implicitly require the content distributor to keep a record that associates each index with the actual identifying information for the corresponding user (e.g., name, address, etc.) in order to ensure accountability. In this work, we construct traitor tracing schemes where all of the identifying information about the user can be embedded directly into the user\u27s key and recovered by the tracing algorithm. In particular, the content distributor does not need to separately store any records about the users of the system, and honest users can even remain anonymous to the content distributor.
The main technical difficulty comes in designing tracing algorithms that can handle an exponentially large universe of possible identities, rather than just a polynomial set of indices . We solve this by abstracting out an interesting algorithmic problem that has surprising connections with seemingly unrelated areas in cryptography. We also extend our solution to a full ``broadcast-trace-and-revoke\u27\u27 scheme in which the traced users can subsequently be revoked from the system. Depending on parameters, some of our schemes can be based only on the existence of public-key encryption while others rely on indistinguishability obfuscation
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