Attacks on StreamHash 2

StreamHash 2 is a hash function proposed by Michał Trojnara at the Cryptography and Security Systems in 2011 Conference. This algorithm is a member of StreamHash family which was first introduced in 2008 during the SHA-3 Competition. In this paper we will show collision attacks on the internal state of the StreamHash 2 hash function with complexity about 2^8n for the 32n-bit version of the algorithm and its reduced version with complexity 2^8n. We will also show its application to attacking the full StreamHash 2 function (finding a collision on all output bits) with complexity about 2^88 . We will try to show that any changes made to the construction (for instance the ones proposed for StreamHash 3) will have no effect on the security of the family due to critical fault build into the compression function

Libertariańskie poglądy na policję i sądy w ujęciu Murraya Newtona Rothbarda

In this article were presented proposals of Murray Newton Rothbard, one of the main representatives of libertarianism, on the police and the courts – services which are regarded by many as necessary to maintain within the equally necessary – in their opinion – the state. As we know, the state does not have its own money, in addition to those taken from their citizens by force in the form of taxes. Rothbard solutions are thus intended to prevent coercion, both on the side of using the services and those who provide these services. Due to the nature of libertarian ideas, which are characterized by simplicity and a strong emphasis on the element of freedom, this article is contained in the short form and does not indicate the specific imperatives of action.W artykule zostały przedstawione propozycje Murraya Newtona Rothbarda – jednego z głównych przedstawicieli libertarianizmu – na temat policji i sądów, czyli służb, które przez wielu są uważane jako konieczne do utrzymywania porządku w ramach równie koniecznego – ich zdaniem – państwa. Jak wiadomo, państwo nie posiada własnych pieniędzy, oprócz tych, które przymusem odbiera obywatelom w postaci podatków. Rozwiązania Rothbarda mają za zadanie uniknąć przymusu zarówno po stronie korzystających z usług, jak i tych, którzy te usługi świadczą. Ze względu na charakter libertariańskich poglądów, które cechuje prostota i silny nacisk na element wolności, artykuł ten zawiera się w krótkiej formie i nie wskazuje konkretnych imperatywów działania

The effect of ethanol concentration on the morphological and molecular preservation of insects for biodiversity studies

Traditionally, insects collected for scientific purposes have been dried and pinned, or preserved in 70% ethanol. Both methods preserve taxonomically informative exoskeletal structures well but are suboptimal for preserving DNA for molecular biology. Highly concentrated ethanol (95-100%), preferred as a DNA preservative, has generally been assumed to make specimens brittle and prone to breaking. However, systematic studies on the correlation between ethanol concentration and specimen preservation are lacking. Here, we tested how preservative ethanol concentration in combination with different sample handling regimes affect the integrity of seven insect species representing four orders, and differing substantially in the level of sclerotization. After preservation and treatments (various levels of disturbance), we counted the number of appendages (legs, wings, antennae, or heads) that each specimen had lost. Additionally, we assessed the preservation ofDNAafter long-term storage by comparing the ratio of PCR amplicon copy numbers to an added artificial standard. We found that high ethanol concentrations indeed induce brittleness in insects. However, the magnitude and nature of the effect varied strikingly among species. In general, ethanol concentrations at or above 90% made the insects more brittle, but for species with robust, thicker exoskeletons, this did not translate to an increased loss of appendages. Neither freezing the samples nor drying the insects after immersion in ethanol had a negative effect on the retention of appendages. However, the morphology of the insects was severely damaged if they were allowed to dry. We also found thatDNApreserves less well at lower ethanol concentrations when stored at room temperature for an extended period. However, the magnitude of the effect varies among species; the concentrations at which the number of COI amplicon copies relative to the standard was significantly decreased compared to 95% ethanol ranged from 90% to as low as 50%. While higher ethanol concentrations positively affect long-term DNA preservation, there is a clear trade-off between preserving insects for morphological examination and genetic analysis. The optimal ethanol concentration for the latter is detrimental for the former, and vice versa. These trade-offs need to be considered in large insect biodiversity surveys and other projects aiming to combine molecular work with traditional morphology-based characterization of collected specimens

MHC, parasites and antler development in red deer : no support for the Hamilton & Zuk hypothesis

The Hamilton-Zuk hypothesis proposes that the genetic benefits of preferences for elaborated secondary sexual traits have their origins in the arms race between hosts and parasites, which maintains genetic variance in parasite resistance. Infection, in turn, can be reflected in the expression of costly sexual ornaments. However, the link between immune genes, infection, and the expression of secondary sexual traits has rarely been investigated. Here, we explored whether the presence and identity of functional variants (supertypes) of the highly polymorphic major histocompatibility complex (MHC), which is responsible for the recognition of parasites, predict the load of lung and gut parasites and antler development in the red deer (Cervus elaphus). While we found MHC supertypes to be associated with infection by a number of parasite species, including debilitating lung nematodes, we did not find support for the Hamilton-Zuk hypothesis. On the contrary, we found that lung nematode load was positively associated with antler development. We also found that the supertypes that were associated with resistance to certain parasites at the same time cause susceptibility to others. Such tradeoffs may undermine the potential genetic benefits of mate choice for resistant partners

MHC influences infection with parasites and winter survival in the root vole Microtus oeconomus

Selective pressure from parasites is thought to maintain the polymorphism of major histocompatibility complex (MHC) genes. Although a number of studies have shown a relationship between the MHC and parasitic infections, the fitness consequences of such associations are less well documented. In the present paper, we characterised the variation in exon 2 of MHC class II DRB gene in the root vole and examined the effects of that gene on parasite prevalence and winter survival. We identified 18 unique exon 2 sequences, which translated into 10 unique amino acid sequences. Phylogenetic analysis revealed the presence of three distinct clusters, and allele distributions among these individuals suggested that the clusters correspond to three different loci. Although the rate of synonymous substitutions (dS) exceeded the rate of nonsynonymous substitutions (dN) across sequences, implying purifying selection, dN was significantly elevated at antigen-binding sites, suggesting that these sites could be under positive selection. Screening for parasites revealed a moderate prevalence of infection with gastrointestinal parasites (24 % infected), but a high infection rate for blood parasites (56 % infected). Infection with the blood parasite Babesia ssp. decreased survival almost twofold (25.7 vs. 13.9 %). Animals possessing the amino acid sequence AA*08 survived better than others (44.9 vs. 22 %), and they were infected with Babesia ssp. less often (13.9 vs 25.7 %). In contrast, individuals carrying allele AA*05 were infected more often (31.7 vs. 15.3 %). Heterozygosity at one of the putative loci was associated with a lower probability of infection with Babesia ssp., but at the other locus, the association was reversed. The unexpected latter result could be at least partly explained by the increased frequency of the susceptible allele AA*05 among heterozygotes. Overall, we demonstrate that infection with Babesia ssp. is a strong predictor of winter survival and that MHC genes are important predictors of infection status as well as survival in the root vole

Optimizing insect metabarcoding using replicated mock communities

1. Metabarcoding (high-throughput sequencing of marker gene amplicons) has emerged as a promising and cost-effective method for characterizing insect community samples. Yet, the methodology varies greatly among studies and its performance has not been systematically evaluated to date. In particular, it is unclear how accurately metabarcoding can resolve species communities in terms of presence-absence, abundance and biomass.2. Here we use mock community experiments and a simple probabilistic model to evaluate the effect of different DNA extraction protocols on metabarcoding performance. Specifically, we ask four questions: (Q1) How consistent are the recovered community profiles across replicate mock communities?; (Q2) How does the choice of lysis buffer affect the recovery of the original community?; (Q3) How are community estimates affected by differing lysis times and homogenization? and (Q4) Is it possible to obtain adequate species abundance estimates through the use of biological spike-ins?3. We show that estimates are quite variable across community replicates. In general, a mild lysis protocol is better at reconstructing species lists and approximate counts, while homogenization is better at retrieving biomass composition. Small insects are more likely to be detected in lysates, while some tough species require homogenization to be detected. Results are less consistent across biological replicates for lysates than for homogenates. Some species are associated with strong PCR amplification bias, which complicates the reconstruction of species counts. Yet, with adequate spike -in data, species abundance can be determined with roughly 40% standard error for homogenates, and with roughly 50% standard error for lysates, under ideal conditions. In the latter case, however, this often requires species-specific reference data, while spike -in data generalize better across species for homogenates.4. We conclude that a nondestructive, mild lysis approach shows the highest promise for the presence/absence description of the community, while also allowing future morphological or molecular work on the material. However, homogeniza- tion protocols perform better for characterizing community composition, in par- ticular in terms of biomass