Gilat Satellite Networks (Israel)

Verticillium dahliae is a soilborne fungal pathogen affecting many economically important crops that can also infect weeds and rotational crops with no apparent disease symptoms. The main research goal was to test the hypothesis that V. dahliae populations recovered from asymptomatic rotational crops and weed species are evolutionarily and genetically distinct from symptomatic hosts. We collected V. dahliae isolates from symptomatic and asymptomatic hosts growing in fields with histories of Verticillium wilt of potato in Israel and Pennsylvania (United States), and used genotyping-by-sequencing to analyze the evolutionary history and genetic differentiation between populations of different hosts. A phylogeny inferred from 26,934 single-nucleotide polymorphisms (SNPs) in 126 V. dahliae isolates displayed a highly clonal structure correlated with vegetative compatibility groups, and isolates grouped in lineages 2A, 2B824, 4A, and 4B, with 77% of the isolates in lineage 4B. The lineages identified in this study were differentiated by host of origin; we found 2A, 2B824, and 4A only in symptomatic hosts but isolates from asymptomatic hosts (weeds, oat, and sorghum) grouped exclusively within lineage 4B, and were genetically indistinguishable from 4B isolates sampled from symptomatic hosts (potato, eggplant, and avocado). Using coalescent analysis of 158 SNPs of lineage 4B, we inferred a genealogy with clades that correlated with geographic origin. In contrast, isolates from asymptomatic and symptomatic hosts shared some of the same haplotypes and were not differentiated. We conclude that asymptomatic weeds and rotational hosts may be potential reservoirs for V. dahliae populations of lineage 4B, which are pathogenic to many cultivated hosts.

Abstract AimsManagement of silvo-pastoral systems in planted and natural forests in semi-arid Mediterranean regions often employs seasonal night corrals for animal protection. This management system changes the spatial distribution of animal excreta, resulting in a net transfer of soil mineral resources and their accumulation in the corrals. After abandonment, corrals are colonized by ruderal species, becoming focal sources for their spread in the forest. We aimed to implement a rational management of seasonal sheep corrals based on a better understanding of the vegetation processes occurring in abandoned corrals, in order to alleviate their negative impact in the forest.MethodsRelationships between temporal changes in the vegetation, the soil seed-bank and levels of soil nutrients were studied in a chronosequence of abandoned sheep corrals and compared with nearby reference plots in planted Eucalyptus forests grazed by sheep in the semi-arid North-Western Negev, Israel. The region has a bi-seasonal Mediterranean climate, with high dominance of annual species in the grazing range.Important FindingsAbandoned sheep corrals were colonized by seeds of ruderals originating in older abandoned corrals. Subsequent successional changes occur at a slow rate, driven by the depletion of soil resources in the abandoned corrals, and were still in progress 20 years after abandonment. Ruderals were gradually replaced, first by taller grasses and followed by short grasses, but most forbs and particularly geophytes did not recover during this period. Recovery of the original herbaceous vegetation in the corrals was through seed dispersal from the surrounding vegetation, not from the original soil seed-bank remaining in the corrals after abandonment. Ruderal species in the grazed, planted forests behave as patch-tracking metapopulations. Their persistency depends on constant creation of new corrals compensating for the gradually dwindling populations in older abandoned corrals, and on the availability of dispersal vectors.

Far End Crosstalk (FEXT) in a twisted pair cable is the most dominant noise impairment in short loops for VDSL2 systems. Its impact significantly reduces the VDSL2 modems performance and in some cases might reduce the modem throughput by more than 50%. Canceling the FEXT impact using Dynamic Spectral Management Level 3 (DSM L3, aka Vectoring aka FEXT Cancellation) is an emerging technology for high rates data traffic over copper (Up to 100Mbit/sec). We have developed an eight VDSL2 modems prototype with DSM L3 capabilities. In this article we introduce an overview of our system design and a variety of tests results that reflect the DSM L3 potential.

Abstract A coded antipodal communication system operating over a Rayieigh fading channel is considered. A partial Side Information (SI) scheme is addressed, where the receiver has an access to the sum of received faded energies over several consecutive symbols. The generalized cut‐off rate is examined both for the independent and for the correlated fading models, and conclusions regarding the usefulness of this particular SI scheme are drawn.

This article focuses on code design and code selection rules under power and decoding delay constraints for an antipodal (BPSK) modulated and convolutionally encoded communication system. The system operates over a slowly fading AWGN channel, described by the block-fading model. We emphasize perfect coherent detection with maximum likelihood decoding assuming ideal channel information (the instantaneous fading values). The dominant design criterion in this scenario is the code diversity level in terms of blocks while the standard Hamming distance plays a secondary role. A code design procedure, based on maximum distance separable (MDS) cyclic block codes is presented along with a code-search algorithm. The performance results of selected codes are assessed via simulation and compared to those achieved by Reed-Solomon codes with erasure and error decoding.

The correlated Rician channel is a useful model for a slowly fading channel, in which the complex fading process is composed of two quadrature Gaussian processes with a given autocorrelation function. For slow fading the correlation between adjacent symbols is relatively high. The authors investigate the achievable error probabilities over the channel, employing coherent detection and ideal side information on the realization of the fading processes at the receiver. An underlying decoding delay constraint which precludes the use of (ideal) interleaving is assumed. Coded BPSK performance is addressed both with and without the piecewise constant approximation (according to which the fading value remains constant during the symbol duration). For the latter case, that is no piecewise constant approximation, the analysis relies on the Fredholm determinant associated with the fading process autocorrelation function. The authors focus on the exponentially correlated channel. The "worst case" pairs of codewords are identified. The exponential behavior of the error probability with random coding (and i.i.d. Gaussian inputs) is analyzed, and the behavior of the cut-off rate and capacity is addressed. The results enhance the insight to the effect of the basic parameters governing the performance and these are examined in view of previous works and compared to relevant performance results for the block-fading channel model.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The interaction of two diseases — Verticillium wilt, caused byVerticillium dahliae, and early blight, caused byAlternaria solani — with salinity was investigated. The use of a system of two overlapping overhead irrigation lines enabled results to be obtained under a continuous gradient of salinity. Three cultivars were investigated, namely, Cara, Desiree and Nicola. The results illustrate the increase in symptom expression of the two diseases, as well as in associated characters such as height and maturity, in the presence of salt. Differences existed between cultivars in their response to the diseases in the presence of varying levels of salt.

Clinical and pathological changes suggesting an acute case of photo-sensitivity were observed in a flock of ostriches. A preliminary diagnosis of parsley (Petroselinum sativum)-induced photosensitisation was confirmed by experimental reproduction of the typical lesions in ducks. This seems to be the first report on natural and experimental induction of photosensitivity in ostriches and ducks caused by the ingestion of parsley.

Abstract The Coccids Antonina graminis and Odonaspis ruthae live on lawn grasses in southern Israel throughout the year. The main period of reproduction was in the summer, and it almost ceased below 17 °C. Seasonal fluctuations in A. graminis populations were characterized by one peak ‐ in summer ‐ in the semi‐arid zone, and by two peaks ‐ in summer and in winter ‐ in the arid zone.ZusammenfassungZur Phänologie von Antonina graminis (Mask.) (Hom., Pseudococcidae) und Odonaspis ruthae Kot. (Hom., Diaspididae) auf Rasen in Süd‐IsraelDie Schildläuse Antonina graminis und Odonaspis ruthae befinden sich das ganze Jahr über auf Rasenflächen im südlichen Teil Israels. Ihr Dichte‐Maximum wurde im Sommer beobachtet; als die Temperaturen unter 17 °C sanken, hörte ihre Fortpflanzung beinahe auf. Charakteristisch für A. graminis‐Populationen sind ein Höhepunkt im Sommer in der semi‐ariden Zone und 2 Höhepunkte, im Sommer und Winter, in der ariden Zone.