Small Number Of Hosts Research Articles

High Throughput VMs Placement With Constrained Communication Overhead and Provable Guarantees

Placement of VMs in the cloud is one of the most fundamental problems in systems research. Traditionally, placement algorithms assume that the schedulers have complete information about the currently available resources at each host. However, this assumption is in many cases unrealistic, as gathering fresh status information from each of the thousands of hosts in a large data center incurs excessive communication overhead, which results in long queueing delays. Efforts to resolve this problem by employing several parallel schedulers typically exhibit collisions when several schedulers are simultaneously trying to place VMs on the same host. Our work analyzes the performance of various placement algorithms and provides empirical evidence that using multiple randomized schedulers obtains high throughput, while significantly decreasing both the communication overhead, and the number of collisions between schedulers. We, therefore, introduce Adaptive Partial State Random (APSR) – an efficient parallel random resource management algorithm that samples only from a small number of hosts and dynamically adjusts the degree of parallelism to provide provable guarantees on the probability of collisions between distinct schedulers. We formally analyze APSR, evaluate it on real workloads, and integrate it into the popular OpenStack cloud management platform. Our evaluation shows that APSR matches the throughput provided by other parallel schedulers, while achieving up to 13x lower decline ratio and a reduction of over 85% in communication overheads.

Peculiarities of the epizootic process in strongylatosis of the gastrointestinal tract of sheep and evaluation of the quality of mutton

The article is devoted to the study of the peculiarities of the epizootic process in strongylatosis of the gastrointestinal tract of sheep and the assessment of the quality of mutton in mixed helminthiasis. The work on the study of the helminthofauna of strongylates was carried out on sheep farms of the Kursk region. In order to study the spreading of strogilatoses, the re-search of helminthic and larvoscopic of feces from 1754 sheep was carried out.The abomasum and intestines of 126 sheep of different ages were subjected to the complete helminthological autopsy. The authors report that strongylatoses of the digestive tract of sheep are widely spread in the Kursk region. Up to 92% of sheep of all ages are infected with a combina-tion of strongylates of various species. 13 species of strongylates from 8 kinds have been registered on sheep farms. Representatives of the genera Ostertagia, Trichostrongylus and Nematodir dominate. It is revealed that the distribution of the number of parasites in the host population is over-dispersed, the majority of sheep are infected with an insignificant number of strongylates, and the main part of helminths is concentrated in a relatively small number of hosts. The dynamics of infection of sheep of different ages and isolation of stron-gylates eggs were studied. Data on the sex ratio of strongylates parasitic on sheep, de-pending on the season of the year, are given. The research results confirm that in recent years the tendency of infection of sheep with trichostrongilus is increased. In more than 30% of cases, mixed invasion by various types of helminthes is registered. At the same time, dicroceliotic-strongylatous invasion, fasciolous-strongylatous and combined inva-sion with strongylates and thin-necked cysticercus are of the greatest spread. Associative invasion has a pronounced negative impact on the quality of mutton. By assessing the quality of mutton, it was found that only 27.26% of sheep with mixed helminthiasis belong to the 1st category of fatness, 72.8% belong to the 2nd category. Mutton obtained from sheep with mixed helminthiasis, fresh meat, has no differences with the meat of non-invasive animals. After 72 hours of storage, mutton of the 2nd category of fatness has a dubious re-action to peroxidase and with copper sulfate, the pH indicator is in the range of 6.1-6.2. The total number of microorganisms (CFU / g) exceeds the standard by two orders of magnitude after 5 days of storage. The slaughter output of carcasses of the 1st and 2nd categories of fatness from sheep infested with different types of helminths with a high intensity of invasion by strongylates is less by 1.8% and 5.4%, respectively, than in the group of non-invasive an-imals.

First Report of Phytopythium oedochilum Causing Root Rot on Coreopsis lanceolata in Italy

HomePlant DiseaseVol. 106, No. 2First Report of Phytopythium oedochilum Causing Root Rot on Coreopsis lanceolata in Italy PreviousNext DISEASE NOTE OPENOpen Access licenseFirst Report of Phytopythium oedochilum Causing Root Rot on Coreopsis lanceolata in ItalyA. Garibaldi, D. Bertetti, G. Tabone, I. Luongo, and M. L. GullinoA. GaribaldiCentre of Competence AGROINNOVA, University of Torino, 10095 Grugliasco, ItalySearch for more papers by this author, D. BertettiCentre of Competence AGROINNOVA, University of Torino, 10095 Grugliasco, ItalySearch for more papers by this author, G. TaboneCentre of Competence AGROINNOVA, University of Torino, 10095 Grugliasco, ItalySearch for more papers by this author, I. LuongoDISAFA, University of Torino, 10095 Grugliasco, ItalySearch for more papers by this author, and M. L. Gullino†Corresponding author: M. L. Gullino; E-mail Address: [email protected]https://orcid.org/0000-0002-7706-1915Centre of Competence AGROINNOVA, University of Torino, 10095 Grugliasco, ItalySearch for more papers by this authorAffiliationsAuthors and Affiliations A. Garibaldi1 D. Bertetti1 G. Tabone1 I. Luongo2 M. L. Gullino1 † 1Centre of Competence AGROINNOVA, University of Torino, 10095 Grugliasco, Italy 2DISAFA, University of Torino, 10095 Grugliasco, Italy Published Online:16 Jan 2022https://doi.org/10.1094/PDIS-06-21-1318-PDNAboutSectionsPDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Corepsis lanceolata, common name lance-leaved coreopsis, is a perennial herbaceous plant belonging to the family Compositae, used in beds and mixed borders, where it flowers for a long period. During the summer of 2020, twenty-five 5-month-old potted plants of C. lanceolata growing in a private garden located near Campiglia Cervo (Biella province, northern Italy) showed stunted growth and general decay. Leaves of affected plants yellowed, collapsed, and dried. Stunted roots exhibited symptoms of rot. The most affected plants died. Affected roots were washed thoroughly, surface sterilized for 30 s in a 1% NaOCl solution, and then rinsed with sterile water. Small fragments (about 2 mm2) were excised from the margins of affected root tissues and plated on the selective medium for oomycetes (PDA-BNPRA-HMI) described by Masago et al. (1977). A Pythium-like organism was consistently isolated and transferred to corn meal agar (CMA). Then, several whitish mycelial disks (10 mm in diameter) of isolate 20-29-4 were taken from colonies grown on CMA and floated on water with soil extract (Erwin and Ribeiro 1996) contained in Petri plates. Plates were maintained at room temperature. After 8 days, hyphae 2.8 to 4.8 (average 3.6) µm in width produced subglobose to pyriform sporangia, measuring 17.0 to 27.0 × 20.6 to 59.3 (average 22.4 × 36.7) µm. Oospores were not observed. The DNA of the isolate 20-29-4 was extracted using the l’E.Z.N.A. Fungal DNA Mini Kit (Omega Bio-Tek, Darmstadt, Germany). The internal transcribed spacer (ITS) region of rDNA was amplified using the primers ITS1/ITS4 (White et al. 1990) and sequenced. BLAST analysis of the 811 bp segment (GenBank accession no. MZ144196) showed a 100% identity with the ex-type CBS 292.37 of Phytopythium oedochilum (GenBank accession no. AY598664). Pathogenicity tests were performed on three healthy plants of C. lanceolata using the isolate 20-29-4. The inoculum was obtained by growing the isolate on a mixture of wheat and hemp kernels (2:1) for 15 days. Infested kernels were mixed (4 g/liter) into a steam disinfested substrate consisting of a mix of sphagnum peat/pomix/pine bark/clay (50:20:20:10) in which C. lanceolata plants were transplanted. Three control plants were transplanted into a steam disinfested soil treated with uninoculated kernels (4 g/liter). All plants were maintained in a greenhouse at temperatures ranging from 16 to 26°C. In the months following inoculation, plants showed stunting and a general decay. Three months after inoculation, a microorganism with the morphological characteristics of P. oedochilum was constantly reisolated from stunted roots. Controls remained symptomless. P. oedochilum has been reported on a small number of hosts in which the Coreopsis genus is not included (Farr and Rossman 2021). This is the first report of P. oedochilum on C. lanceolata in Italy as well as worldwide. The economic consequences of this disease are currently limited. However, since the use of C. lanceolata is becoming popular, this disease may discourage gardeners and commercial growers from suggesting this ornamental plant in gardens and landscaping.The author(s) declare no conflict of interest.

Automatic barcode gap discovery reveals diverse clades of Rhipicephalus spp. and Haemaphysalis spp. ticks from small mammals in 'Asir, Saudi Arabia

BackgroundThe ixodid tick genera Rhipicephalus and Haemaphysalis contain several species of medical and/or veterinary importance, but their diversity in some regions of the world remains under-explored. For instance, very few modern studies have been performed on the taxonomy of these genera on the Arabian Peninsula.MethodsIn this study, we trapped small mammals in the 'Asir Mountains of south-western Saudi Arabia and collected tick specimens for morphological examination and molecular barcoding, targeting three mitochondrial loci: cox1, 16S rRNA and 12S rRNA.ResultsWe obtained a total of 733 ticks (608 Haemaphysalis spp. and 125 Rhipicephalus spp.) from 75 small mammal hosts belonging to six species. All tick specimens were immature except for nine adults recovered from a hedgehog (Paraechinus aethiopicus). Morphologically, the Rhipicephalus ticks resembled R. camicasi, but the Haemaphysalis ticks showed differences in palp morphology compared with species previously described from Saudi Arabia. Phylogenetic analysis and automatic barcode gap discovery identified a novel clade of Rhipicephalus sp. representing most of the nymphs. This was most closely related to R. leporis, R. guilhoni and R. linnaei. The adult ticks and a small proportion of nymphs clustered with R. camicasi sequences from a previous study. Finally, the Haemaphysalis nymphs formed two distinct clades that were clearly separated from all reference sequences but closest to some African species.ConclusionsThis apparent high level of tick diversity observed in a single study site of only ~ 170 km2, on a relatively small number of hosts, highlights the potential for the discovery of new tick species on the Arabian Peninsula.Graphical

Metabarcoding of eukaryotic parasite communities describes diverse parasite assemblages spanning the primate phylogeny.

Despite their ubiquity, in most cases little is known about the impact of eukaryotic parasites on their mammalian hosts. Comparative approaches provide a powerful method to investigate the impact of parasites on host ecology and evolution, though two issues are critical for such efforts: controlling for variation in methods of identifying parasites and incorporating heterogeneity in sampling effort across host species. To address these issues, there is a need for standardized methods to catalogue eukaryotic parasite diversity across broad phylogenetic host ranges. We demonstrate the feasibility of a metabarcoding approach for describing parasite communities by analysing faecal samples from 11 nonhuman primate species representing divergent lineages of the primate phylogeny and the full range of sampling effort (i.e. from no parasites reported in the literature to the best-studied primates). We detected a number of parasite families and regardless of prior sampling effort, metabarcoding of only ten faecal samples identified parasite families previously undescribed in each host (x̅=8.5 new families per species). We found more overlap between parasite families detected with metabarcoding and published literature when more research effort-measured as the number of publications-had been conducted on the host species' parasites. More closely related primates and those from the same continent had more similar parasite communities, highlighting the biological relevance of sampling even a small number of hosts. Collectively, results demonstrate that metabarcoding methods are sensitive and powerful enough to standardize studies of eukaryotic parasite communities across host species, providing essential new tools for macroecological studies of parasitism.

Bioinformatic evidence of widespread priming in type I and II CRISPR-Cas systems

ABSTRACTCRISPR-Cas systems provide bacteria and archaea with adaptive immunity against invading genetic elements, such as plasmids, bacteriophages and archaeal viruses. They consist of cas genes and CRISPR loci, which store genetic memories of previously encountered invaders as short sequences termed spacers. Spacers determine the specificity of CRISPR-Cas defence and immunity can be gained or updated by the addition of new spacers into CRISPR loci. There are two main routes to spacer acquisition, which are known as naïve and primed CRISPR adaptation. Naïve CRISPR adaptation involves the de novo formation of immunity, independent of pre-existing spacers. In contrast, primed CRISPR adaptation (priming) uses existing spacers to enhance the acquisition of new spacers. Priming typically results in spacer acquisition from locations near the site of target recognition by the existing (priming) spacer. Primed CRISPR adaptation has been observed in several type I CRISPR-Cas systems and it is potentially widespread. However, experimental evidence is unavailable for some subtypes, and for most systems, priming has only been shown in a small number of hosts. There is also no current evidence of priming by other CRISPR-Cas types. Here, we used a bioinformatic approach to search for evidence of priming in diverse CRISPR-Cas systems. By analysing the clustering of spacers acquired from phages, prophages and archaeal viruses, including strand and directional biases between subsequently acquired spacers, we demonstrate that two patterns of primed CRISPR adaptation dominate in type I systems. In addition, we find evidence of a priming-like pathway in type II CRISPR-Cas systems.

Tempest: Temporal Dynamics in Anonymity Systems

Abstract Many recent proposals for anonymous communication omit from their security analyses a consideration of the effects of time on important system components. In practice, many components of anonymity systems, such as the client location and network structure, exhibit changes and patterns over time. In this paper, we focus on the effect of such temporal dynamics on the security of anonymity networks. We present Tempest, a suite of novel attacks based on (1) client mobility, (2) usage patterns, and (3) changes in the underlying network routing. Using experimental analysis on real-world datasets, we demonstrate that these temporal attacks degrade user privacy across a wide range of anonymity networks, including deployed systems such as Tor; pathselection protocols for Tor such as DeNASA, TAPS, and Counter-RAPTOR; and network-layer anonymity protocols for Internet routing such as Dovetail and HORNET. The degradation is in some cases surprisingly severe. For example, a single host failure or network route change could quickly and with high certainty identify the client’s ISP to a malicious host or ISP. The adversary behind each attack is relatively weak – generally passive and in control of one network location or a small number of hosts. Our findings suggest that designers of anonymity systems should rigorously consider the impact of temporal dynamics when analyzing anonymity.

Pathologies of Oligacanthorhynchus pardalis (Acanthocephala, Oligacanthorhynchidae) in Leopardus tigrinus (Carnivora, Felidae) in Southern Brazil

In Brazil, Oligacanthorhynchus pardalis (Westrumb, 1821) Schmidt, 1972 has been observed in five species of wild felines. In the present study, five roadkilled oncillas (Leopardus tigrinus Schreber, 1775) were collected in the State of Rio Grande do Sul, Brazil. Chronic lesions caused by O. pardalis were observed in the small intestine of one of the specimens. Histological examination identified a well-defined leukocyte infiltration and an area of collagenous fibrosis. Only males parasites (n = 5) were found, with a prevalence of 20%. The life cycle of Oligacanthorhynchus species is poorly known, although arthropods may be their intermediate hosts. The low prevalence encountered may be related to the small number of hosts examined, and the reduced ingestion of arthropods infected by larvae of O. pardalis. This is the first report of O. pardalis parasitizing L. tigrinus in the Brazilian state of Rio Grande do Sul.

The dynamics of energy allocation in adult arrhenotokous and thelytokous Venturia canescens

AbstractThe ability to adjust resource allocation to the quality of the environment has broad implications for animal reproductive success. Organisms with complex life cycles that may experience various selection pressures during their lifetime are expected to evolve mechanisms to modulate the resource allocation strategies adopted during ontogeny to the conditions encountered by the adult. In the parasitoid Venturia canescens Gravenhorst (Hymenoptera: Ichneumonidae), thelytoky appears to have been selected for in anthropogenic habitats, where hosts are relatively numerous and food is absent, and arrhenotoky in natural habitats where hosts are more scarce and food is present. A previous study postulated that during their juvenile stage, females of both reproductive modes adopt strategies of energy allocation in accordance with these conditions, possibly providing a direct short‐term advantage to arrhenotokous forms, which partially co‐occur with thelytokous forms under natural conditions. To test this assumption, we provided daily adult thelytokous and arrhenotokous females with a small number of hosts together with food. To compare their lifetime resource allocation strategies, we recorded wasp longevities, egg loads, and carbohydrate reserves in wasps of different ages. Our analysis indicates that thelytokous females are able, to a certain extent, to cope with these conditions, because they reached the same longevity as arrhenotokous females. Nevertheless, thelytokous females suffered from a higher degree of time limitation compared with arrhenotokous ones, and arrhenotokous wasps appeared to maintain their energetic advantage over the adult stage. These results provide new insights, and point to the consideration of other activities, such as flight performance and/or ability to reach food and hosts, in the understanding of the role of resource allocation strategies in the maintenance of sex in this species.

Experimental validation of the ON–OFF packet-level model for IP traffic

Much effort has been spent in analyzing and modeling IP traffic from the perspective of the packet-counting process that aggregates packet arrivals over fixed time intervals. Much less has been done regarding the modeling of the patterns of arrival of IP packets. The main purpose of this study was to determine whether the ON–OFF packet-level model is an adequate model. As shown in this paper, at the aggregate level the answer is yes, to great accuracy. Further, it compares favorably to other models such as modulated Poisson arrivals. At the IP-flow level, the ON–OFF model is not adequate; rather, an active–inactive model is appropriate. The reason is that the rate in the ON state greatly varies from an ON period to the other. We further argue experimentally that it is only necessary to consider a small number of hosts and host pairs to account for the impact on a queuing system and on the long-term variability of the traffic. The starting point of the approach is to analyze and model traffic along the dimensions of packet size and packet inter-arrival processes. The method is applied to well-known and publicly available traces from the ITA and NLANR repositories, as well as traces of traffic captured in our institution premises.

Attachment sites and frequency distribution of erythraeid mites, Leptus indianensis (Acari: Prostigmata), ectoparasitic on harvestmen, Leiobunum formosum (Opiliones).

Host attachment sites and frequency distribution of parasitism were investigated for the larval erythraeid mite Leptus indianensis parasitising a sample of 500 harvestmen. Leiobunum formosum in Tennessee, USA. A significant difference was found in the number of mites attached to different body segments of the harvestmen with the greatest number of mites attached to femurs I-IV. Scanning electron microscopy revealed that the mites attached to smooth areas of the host integument between rows of stout setae. The frequency distribution of mites parasitising the harvestman population was highly clumped (Coefficient of Dispersion = 3.34) with a relatively small number of hosts being parasitised by most of the mites.

Alternative Patch-utilization Strategies in Sympatric Parasitoids (Hymenoptera: Pteromalidae)

This study was designed to characterize the patch-utilization strategies of two sympatric species of parasitoids. The hypothesis is presented that sympatric species that use the same range of hosts may exhibit divergent patch-utilization strategies, possibly allowing for coexistence. The species studied were Muscidifurax raptor Girault & Saunders and M. zaraptor Kogan & Legner, pupa parasites of synanthropic fly species in the southwestern United States. Laboratory behavior experiments demonstrated that these species have alternative strategies of patch utilization. M. raptor has a short handling time and exhibits the apparent strategy of parasitizing as many hosts as possible per patch. M. zaraptor has a longer handling time and generally enters a patch where it parasitizes a small number of hosts, before leaving quickly to search for other patches. Both strategies are accentuated at high parasitoid densities.