Timely processing of big data in collaborative large-scale distributed systems

Today’s Big Data phenomenon, characterized by huge volumes of data produced at very high rates by heterogeneous and geographically dispersed sources, is fostering the employment of large-scale distributed systems in order to leverage parallelism, fault tolerance and locality awareness with the aim of delivering suitable performances. Among the several areas where Big Data is gaining increasing significance, the protection of Critical Infrastructure is one of the most strategic since it impacts on the stability and safety of entire countries. Intrusion detection mechanisms can benefit a lot from novel Big Data technologies because these allow to exploit much more information in order to sharpen the accuracy of threats discovery. A key aspect for increasing even more the amount of data at disposal for detection purposes is the collaboration (meant as information sharing) among distinct actors that share the common goal of maximizing the chances to recognize malicious activities earlier. Indeed, if an agreement can be found to share their data, they all have the possibility to definitely improve their cyber defenses. The abstraction of Semantic Room (SR) allows interested parties to form trusted and contractually regulated federations, the Semantic Rooms, for the sake of secure information sharing and processing. Another crucial point for the effectiveness of cyber protection mechanisms is the timeliness of the detection, because the sooner a threat is identified, the faster proper countermeasures can be put in place so as to confine any damage. Within this context, the contributions reported in this thesis are threefold * As a case study to show how collaboration can enhance the efficacy of security tools, we developed a novel algorithm for the detection of stealthy port scans, named R-SYN (Ranked SYN port scan detection). We implemented it in three distinct technologies, all of them integrated within an SR-compliant architecture that allows for collaboration through information sharing: (i) in a centralized Complex Event Processing (CEP) engine (Esper), (ii) in a framework for distributed event processing (Storm) and (iii) in Agilis, a novel platform for batch-oriented processing which leverages the Hadoop framework and a RAM-based storage for fast data access. Regardless of the employed technology, all the evaluations have shown that increasing the number of participants (that is, increasing the amount of input data at disposal), allows to improve the detection accuracy. The experiments made clear that a distributed approach allows for lower detection latency and for keeping up with higher input throughput, compared with a centralized one. * Distributing the computation over a set of physical nodes introduces the issue of improving the way available resources are assigned to the elaboration tasks to execute, with the aim of minimizing the time the computation takes to complete. We investigated this aspect in Storm by developing two distinct scheduling algorithms, both aimed at decreasing the average elaboration time of the single input event by decreasing the inter-node traffic. Experimental evaluations showed that these two algorithms can improve the performance up to 30%. * Computations in online processing platforms (like Esper and Storm) are run continuously, and the need of refining running computations or adding new computations, together with the need to cope with the variability of the input, requires the possibility to adapt the resource allocation at runtime, which entails a set of additional problems. Among them, the most relevant concern how to cope with incoming data and processing state while the topology is being reconfigured, and the issue of temporary reduced performance. At this aim, we also explored the alternative approach of running the computation periodically on batches of input data: although it involves a performance penalty on the elaboration latency, it allows to eliminate the great complexity of dynamic reconfigurations. We chose Hadoop as batch-oriented processing framework and we developed some strategies specific for dealing with computations based on time windows, which are very likely to be used for pattern recognition purposes, like in the case of intrusion detection. Our evaluations provided a comparison of these strategies and made evident the kind of performance that this approach can provide

Synergistic Effects of Probiotics and Phytobiotics on the Intestinal Microbiota in Young Broiler Chicken

Probiotics and phytobiotics have been studied as in-feed antibiotic alternatives for decades, yet there are no studies on their possible symbiotic effects. In the present study, newly hatched chickens were fed with feeds supplemented either with host-specific Lactobacillus strains (L. agilis and L. salivarius), commercial phytobiotics, or combinations of both. After 13 days of life, crops and caecums were analyzed for bacterial composition (16S rDNA sequencing, qPCR) and activity (bacterial metabolites). Crop and caecum samples were also used to study the ex vivo survival of a broiler-derived extended-spectrum beta-lactamase (ESBL) producing Escherichia coli strain. In the crop, combinations of probiotics and phytobiotics, but not their single application, increased the dominance of lactobacilli. The single application of phytobiotics reduced the metabolite concentrations in the crop, but certain combinations synergistically upregulated the metabolites. Changes in the qualitative and quantitative composition of the caecal microbiota were less pronounced than in the crop. Acetate concentrations were significantly lower for phytobiotics or the L. agilis probiotic strain compared to the control group, but the L. salivarius probiotic showed significantly higher acetate concentrations alone or in combination with one phytobiotic. The synergistic effects on the reduction of the ex vivo survival of an ESBL producing E. coli strain in crop or caecum contents were also observed for most combinations. This study shows the beneficial synergistic effects of probiotics and phytobiotics on the intestinal bacterial composition and their metabolic activity in young broilers. The reduced survival of potentially problematic bacteria, such as ESBL-producing E. coli further indicates that combinations of probiotics and phytobiotics may lead to a more enhanced functionality than their individual supplementation

High predation risk decimates survival during the reproduction season

Predators attack conspicuous prey phenotypes that are present in the environment. Male display behavior of conspicuous nuptial coloration becomes risky in the presence of a predator, and adult males face higher predation risk. High predation risk in one sex will lead to low survival and sex ratio bias in adult cohorts, unless the increased predation risk is compensated by higher escape rate. Here, we tested the hypothesis that sand lizards (Lacerta agilis) have sex-specific predation risk and escape rate. We expected the differences to manifest in changes in sex ratio with age, differences in frequency of tail autotomy, and in sex-specific survival rate. We developed a statistical model to estimate predation risk and escape rate, combining the observed sex ratio and frequency of tail autotomy with likelihood-based survival rate. Using Bayesian framework, we estimated the model parameters. We projected the date of the tail autotomy events from growth rates derived from capture-recapture data measurements. We found statistically stable sex ratio in age groups, equal frequency of tail regenerates between sexes, and similar survival rate. Predation risk is similar between sexes, and escape rate increases survival by about 5%. We found low survival rate and a low number of tail autotomy events in females during months when sand lizards mate and lay eggs, indicating high predator pressure throughout reproduction. Our data show that gravid females fail to escape predation. The risks of reproduction season in an ectotherm are a convolution of morphological changes (conspicuous coloration in males and body allometry changes in gravid females), behavior (nuptial displays), and environmental conditions which challenge lizard thermal performance. Performance of endotherm predators in cold spring months endangers gravid females more than displaying males in bright nuptial coloration

Influence of human gut microbiota on the metabolic fate of glucosinolates

Glucosinolates (GSLs) are secondary metabolites predominantly found in cruciferous vegetables such as broccoli, brussel sprout, cabbage and cauliflower which upon chopping and chewing will release the indigenous plant myrosinase enzyme that catalyzes the hydrolysis of GSLs. This hydrolysis releases a range of breakdown products including isothiocyanates (ITCs), which have been implicated in the cancer-protective effects of cruciferous vegetables. Certain human gut bacteria are able to metabolize GSLs and produce ITCs for human health benefits. In this work, six GSL-metabolizing bacterial strains were isolated from human faecal sample and identified. Most bacteria were capable of producing both nitriles (NITs) and ITCs from the metabolism of GSLs however Enterococcus sp. C213 and Enterococcus faecium KT4S13 produced only NITs. Enterococcus casseliflavus NCCP-53, Escherichia coli O83:H1 NRG 857C and Lactobacillus agilis R16 were able to metabolize different types (allyl, aromatic, methylthioalkyl, methylsulfinylalkyl and indolyl) of GSLs differently over 24 h of in vitro anaerobic fermentations. For all GSLs, ITC production seemed to peak between 4 and 8 h of incubation and then declined due to the inherent instability of ITCs in culture broths and buffers. In contrast, NIT productions gradually increased over time and remained relatively constant. The total percentage products from each GSL metabolism in all three bacteria never reached 100%. Interestingly, E. coli O83:H1 NRG 857C produced methylthioalkyl ITCs and NITs from methylsulfinylalkyl GSLs while E. casseliflavus NCCP-53 produced only methylsulfinylalkyl ITCs from the same GSLs. This difference was due to reductase activity in E. coli O83:H1 NRG 857C intact cells and cell-free extracts that biotransforms the sulfoxide groups of methylsulfinylalkyl GSLs to the sulfide groups. The reductase enzyme is yet to be identified at the gene and protein level, however it has been characterized using cell-free extracts in this work. This reductase is inducible by GSLs, oxygen-independent and requires Mg2+ ion and NADP(H) as co-factors for its activity with optimum pH and temperature at pH 7.0 and 37˚C, respectively. Arylsulfatase activity was also detected in this bacterium. The corresponding recombinant SUL2 enzyme (57 kDa) of E. coli O83:H1 NRG 857C expressed in BL21(DE3) exhibited arylsulfatase activity by desulfating synthetic p-nitrocatachol sulfate substrate with optimum pH and temperature at pH 6.0 and 30˚C, respectively. In addition, GSL-sulfatase activity was detected in crude extracts by being able to desulfate different intact GSLs to produce desulfo-glucosinolates (DS-GSLs) with less efficiency in comparison with the commercially available snail sulfatase from Helix pomatia. The catalytic efficiency of recombinant SUL2 enzyme for GSLs in descending order is as follows; sinigrin > glucoerucin > gluconasturtiin > glucoiberin. The DS-GSLs (except DS-glucoraphanin) then act as substrates for the recombinant GH3 enzyme defived from E. casseliflavus NCCP-53 to produce the corresponding NIT products in NB broths and the buffer with the presence of 5 mM Fe2+ ions. This enzyme (79 kDa) showed β-O-glucosidase activity for p-nitrophenyl β-D-glucopyranoside with optimum pH and temperature at pH 7.0 and 37˚C, respectively. NIT productions only occurred from the metabolism of intact GSLs in bacterial culture broths, but not in the buffers unless 5 mM Fe2+ ions are present as co-factors. Putative bacterial GSL-degrading enzymes responsible for ITC and NIT productions from GSL metabolisms are inducible by GSL in resting cells experiments. By using two-dimensional gel electrophoresis (2-DE) and liquid chromatography mass spectrometry (LC-MS/MS) for the comparative analysis between proteins obtained from cultures of L. agilis R16 and E. coli O83:H1 NRG 857C with and without GSL supplementation, upregulated/distinct proteins that may be involved in the metabolism of GSLs by these bacteria were identified. These proteins belong to (sugar) transport system, carbohydrate metabolism especially kinases and oxidoreduction process. To date, bacterial GSL-degrading enzyme is yet to be identified.Open Acces

Ant-like Traits in Wingless Parasitoids Repel Attack from Wolf Spiders

A recent study showed that a wingless parasitoid, Gelis agilis, exhibits a suite of ant-like traits that repels attack from wolf spiders. When agitated, G. agilis secreted 6-methyl-5-hepten-2-one (sulcatone), which a small number of ant species produce as an alarm/panic pheromone. Here, we tested four Gelis parasitoid species, occurring in the same food chain and microhabitats, for the presence of sulcatone and conducted two-species choice bioassays with wolf spiders to determine their degree of susceptibility to attack. All four Gelis species, including both winged and wingless species, produced sulcatone, whereas a closely related species, Acrolyta nens, and the more distantly related Cotesia glomerata, did not. In two-choice bioassays, spiders overwhelmingly rejected the wingless Gelis species, preferring A. nens and C. glomerata. However, spiders exhibited no preference for either A. nens or G. areator, both of which are winged. Wingless gelines exhibited several ant-like traits, perhaps accounting for the reluctance of spiders to attack them. On the other hand, despite producing sulcatone, the winged G. areator more closely resembles other winged cryptines like A. nens, making it harder for spiders to distinguish between these two species. C. glomerata was also preferred by spiders over A. nens, suggesting that other non-sulcatone producing cryptines nevertheless possess traits that make them less attractive as prey. Phylogenetic reconstruction of the Cryptinae reveals that G. hortensis and G. proximus are ‘sister’species, with G. agilis, and G.areator in particular evolving along more distant trajectories. We discuss the possibility that wingless Gelis species have evolved a suite of ant-like traits as a form, of mimicry to repel predators on the ground.FWN – Publicaties zonder aanstelling Universiteit Leide

Studies on the biology and ecology of Michigan Phalangida (Opiliones)

http://deepblue.lib.umich.edu/bitstream/2027.42/56388/1/MP144.pd

Ecology of the feral cat (Felis catus) in the tall forests of Far East Gippsland

The house cat, Felis catus, was introduced into Australia with European settlement of the mainland. Since its initial introduction, it now occupies all mainland habitats, Tasmania and many smaller offshore islands. Large numbers of cats were released intentionally into the environment in a misguided attempt to control the spread of other introduced mammalian pests, especially the European rabbit, Oryctolagus cuniculus. The feral cat is an invasive predator that has been implicated in the decline and extinction of many species of native small mammals across Australia, particularly in the arid regions and on offshore islands. Much of the research on feral cats in Australia has occurred in the continent’s arid and semi-arid regions. Consequently, little is known about the ecology of feral cats in tall forests. Additionally, the most generally effective population control technique, poison baiting with sodium monofluoroacetate (compound 1080), has wide ranging applicability in arid and semi arid areas but its use is restricted in the temperate and forested eastern states of Australia due to concerns about impacts on non-target species. This thesis is divided into three parts. Firstly, I review the current knowledge of feral cats, particularly in relation to the actual and potential impact they have on native prey species. Secondly, I investigate the ecology of the feral cat in the temperate tall forests of Far East Gippsland, Victoria. The home range sizes, movement patterns and home range use of feral cats were determined. Thirdly, I examine a new technique for delivering poisons in a feral cat management program. The potential for all Australian non-target species to access the toxicant is examined using a desktop analysis, while field studies examine uptake by non-target species and the dynamics of prey species to determine acceptable times for baiting campaigns. GPS and VHF collars were utilised to obtain fix data for feral cats in Far East Gippsland. Male cats had significantly larger home ranges (MCP100 455 ± 126 ha) than females (105 ± 28 ha), with male home ranges overlapping those of females. Some female home ranges overlapped extensively, with neighbouring females also having overlapping core areas within their ranges. These overlaps in female home ranges, in particular of the core areas, indicate that female cats in Far East Gippsland are tolerant of other females and do not actively exclude them. Compared with the home ranges of feral cats in other regions of Australia and New Zealand, the cats in Far East Gippsland had smaller home ranges than those of cats occupying arid and alpine zones yet larger ranges than those of feral cats living in farmland or grassland. This variation probably reflects the availability of food resources, with cats in resource-poor areas requiring larger home ranges and cats with smaller home ranges generally inhabiting areas with greater, or more accessible, food resources. The use of GPS collars to obtain accurate and high volumes of location data allowed the intra-home range movements of feral cats to be examined in ways not previously possible using conventional VHF radio telemetry. Location data were gathered at three different temporal intervals – 6 hourly, hourly and every 15 minutes. Feral cats followed a Lévy walk-style searching pattern as they moved through their home range. Employing a Lévy walk increases the likelihood of encountering prey items that are distributed sparsely in the environment, in turn maximising the potential hunting return for effort expended. Each of the cats examined had large areas within their home range that they did not enter. To test the hypothesis that this resulted from a scarcity of prey in these areas, trapping grids were established to capture small prey-sized animals. There was no difference in the rate of capture of prey species in the areas of high and zero cat use, thus allowing the food hypothesis to be rejected. Modelling of abiotic environmental parameters was used to determine if these influence home range use. While the models explained much of the variation in the data, the global model was overdispersed, indicating that other unmeasured parameters were influencing home range use. The avoidance of these areas most likely arises from the presence of larger intraguild predators and subsequent employment of predator avoidance strategies by the cats. Managing the abundance of feral cats using poison baiting requires that bait be distributed at times when cats are food-stressed. Generally this occurs in winter when prey species are in natural decline. To determine the most appropriate time for baiting feral cats, trapping grids were established to assess the population demographics of feral cat prey species. The 2 046 trap nights undertaken resulted in 176 captures of five prey-sized species. The breeding periods for the Antechinus spp. occur earlier in Far East Gippsland than would generally be expected based on the latitude and altitude of the trap sites, and have bearing on the optimal time for poison baiting. Based on these findings, the optimal time to manage feral cat populations in Far East Gippsland through poison baiting is between late August and mid November provided that the toxicant is enclosed within a hard shell delivery vehicle (HSDV) that maintains structural integrity or, alternatively, if the baits are suspended above the ground surface and out of reach of lactating female antechinus. Further research is proposed to supplement these findings. Encapsulation of toxicants within an acid soluble HSDV which is then inserted into the bait media is being explored as a potential technique to minimise access of non-target species to the toxicant. A desktop analysis employing a decision tree process was used to examine the potential for non-target access to toxicant delivered in an HSDV. This analysis encompassed all non-aquatic vertebrate species in Australia. significantly fewer species would be susceptible to non-target poisoning if HSDVs were used when compared with directly injecting the toxicant into the bait media. Carnivorous mammals were the most likely to consume both the bait and the HSDV. Using the systemic marker, Rhodamine B (Rb), in the HSDV, the ability of five species of small to mid-sized animals to access toxicants enclosed in the HSDV. This was compared with directly injecting it into the baits. Rhodamine B staining was apparent in the mystacial vibrissae of four of the five species at sites where Rb was injected into the baits. It was also present in three of the four species captured at the sites where the Rb was encapsulated within the HSDV. The longevity of the HSDV within the bait media was tested and found to decreased rapidly following insertion into the bait. This is most likely due to the bait media being slightly acidic. Since that experiment concluded, changes have been made to the pH of baits to extend the integrity of the HSDV and hence reduce leakage. These key findings will allow managers to adopt a more targeted approach when undertaking cat control programs in these habitats. The use of GPS technology to obtain location data has allowed the analysis of intra-home range movements to an extent previously not possible with other techniques. This in turn will allow a more targeted approach to managing feral cats. The use of a decision tree approach to determining the susceptibility of non-target species during a baiting campaign can be applied to other poisoning campaigns regardless of the target species or the toxicant being used

Benthic Community Analysis of Hog Island Bay, Virginia

The benthic infaunal macroinvertebrate communities of Hog Island Bay of the Virginia Eastern Shore were quantitatively sampled at 30 locations on August 31 and September 1, 1995. The primary objectives of this study were: (1) to characterize the subtidal macroinfaunal benthic communities of Hog Island Bay, (2) to examine relationships between abiotic factors and the macroinfaunal communities and (3) to characterize the environmental condition of the system using the Benthic Index of Biotic Integrity (B-IBI) (Weisburg et al. 1997) and the EMAP Benthic Index for the Virginian Province (Strobel et al. 1995). The ecological condition of Hog Island Bay appears to be largely defined by its geographic location and physical processes acting along a coastal zone. Multivariate statistical analyses reveal a community spatial pattern not unlike other temperate estuaries. Outside of a sharp community transition existing in the vicinity of Great Machipongo Inlet, benthic assemblages throughout the study area generally exhibit subtle boundaries and a high degree of internal similarity. When compared among other estuaries and bays in the Virginian Province, community attributes measured for Hog Island Bay were most similar to polyhaline reaches of Chesapeake Bay. Also, both physical and biological data imply that the structure of Virginia\u27s polyhaline benthic communities is different from that occurring in communities north of Virginia. In terms of both the B-IBI and the EMAP index, the benthic community condition of Hog Island Bay may be viewed as exceptional when compared with other systems occurring throughout the Virginian Province