mtDNA data reveal disparate population structures and High Arctic colonization patterns in three intertidal invertebrates with contrasting life history traits

Introduction: Post-glacial climate variation is known to have influenced the distribution of marine species in the North Atlantic. In particular, the Atlantic side of the Arctic has experienced strong fluctuations in both atmospheric and sea surface temperature, as well as seasonal ice coverage since the last glacial maximum (LGM). Here, we aim to unveil the phylogeography and historical demography of three rocky intertidal marine invertebrates showing a trans-Atlantic distribution and presently inhabiting the Arctic: Gammarus oceanicus, Littorina saxatilis and Semibalanus balanoides. Methods: We used a large amount of mitochondrial DNA barcode data, both newly-obtained and stored in public databases. We performed phylogeographic and demographic analyses on 1119 G. oceanicus, 205 L. saxatilis, and 884 S. balanoides sequences. Results: Our results show that all three of these boreal species have expanded their effective population sizes in the high Arctic Svalbard Archipelago since the LGM. Analyses investigating the origin of all these populations point to the eastern Atlantic. Discussion: Based on our results we conclude that the expansion of these boreal species to the Arctic possibly happened during an earlier warm cycle of the Holocene era, and is probably not the result of the recent ‘Atlantification’ of the Arctic. We also discuss the effects of dispersal potential on population structure as an important aspect of comparative biogeographical studies

Human and Organizational Issues for Resilient Communications

Human and organizational issues are able to create both vulnerabilities and resilience to threats. In this chapter, we investigate human and organizational factors, conducted through ethnographic studies of operators and sets of interviews with staff responsible for security, reliability and quality in two different organizations, which own and operate utility networks. Ethnography is a qualitative orientation to research that emphasizes the detailed observation and interview of people in naturally occurring settings. Our findings indicate that 'human error' forms the biggest threat to cyber-security and that there is a need for Security Operational Centres to document all cyber-security accidents. Also, we conclude that it will always be insufficient to assess mental security models in terms of their technical correctness, as it is sometimes more important to know how well they represent prevailing social issues and requirements. As a practical recommendation from this work, we suggest that utility organizations engage in penetration testing and perhaps other forms of vulnerability analysis, not only to discover specific vulnerabilities but also to learn more about the mental models they use

THE CONCEPT OF LAW AND EFFICACY

Jedno od značenja izraza ‘učinkovitost’ odnosi se na činjenicu da se adresati pravnih normi stvarno ponašaju onako kako to od njih zahtijevaju pravne norme. To se značenje izraza obično koristi u filozofskopravnim raspravama glede toga je li učinkovitost bitan element pojma prava. Prema pravnom pozitivizmu, učinkovitost je u nekim slučajevima i na određene načine uvjet važenja (vrijeđenja) pravnih normi i pravnih sustava. S druge strane, pravni je realizam sklon potpunom poistovjećivanju pravnog važenja s učinkovitosti ili njegovu svođenju na učinkovitost. Prema tome, u oba je filozofskopravna pravca učinkovitost u pravilu uključena u oblikovanje njihovih pojmova prava. Međutim, dok pravnopozitivističko shvaćanje ne utječe na najuobičajenije značenje važenja pravne norme (pripadanje pravne norme pravnom sustavu), a utvrđivanjem učinkovitosti kao kriterija postojanja pravnog sustava ne dodaje mnogo objašnjenju pojma prava, pravnorealističko se shvaćanje suočava s ozbiljnim prigovorima glede svoje objašnjavalačke prikladnosti.One of the senses of the term ‘efficacy’ refers to the fact that norm-addresses actually behave as is required of them by legal norms. This sense of the term is one which is generally used within the jurisprudential discussions about whether efficacy is the essential element of the concept of law. According to legal positivism, efficacy is in some cases and in certain ways the condition of legal validity of both legal norms and legal systems. On the other hand, legal realism tends to entirely identify legal validity or reduce it to efficacy. Thus, in both jurisprudential approaches, efficacy tends to play a role in shaping their respective concepts of law. However, while the legal positivistic view does not affect the most standard sense of legal validity of the legal norm (i.e. the legal norms’ membership in the legal system), and does not add much to the explanation of the concept of law by identifying efficacy as the criterion of legal systems’ existence, the legal realistic view is faced with some serious objections regarding its explanatory adequacy

Comparison of measures of marker informativeness for ancestry and admixture mapping

<p>Abstract</p> <p>Background</p> <p>Admixture mapping is a powerful gene mapping approach for an admixed population formed from ancestral populations with different allele frequencies. The power of this method relies on the ability of ancestry informative markers (AIMs) to infer ancestry along the chromosomes of admixed individuals. In this study, more than one million SNPs from HapMap databases and simulated data have been interrogated in admixed populations using various measures of ancestry informativeness: Fisher Information Content (FIC), Shannon Information Content (SIC), F statistics (F_ST), Informativeness for Assignment Measure (I_n), and the Absolute Allele Frequency Differences (delta, δ). The objectives are to compare these measures of informativeness to select SNP markers for ancestry inference, and to determine the accuracy of AIM panels selected by each measure in estimating the contributions of the ancestors to the admixed population.</p> <p>Results</p> <p>F_STand I_nhad the highest Spearman correlation and the best agreement as measured by Kappa statistics based on deciles. Although the different measures of marker informativeness performed comparably well, analyses based on the top 1 to 10% ranked informative markers of simulated data showed that I_nwas better in estimating ancestry for an admixed population.</p> <p>Conclusions</p> <p>Although millions of SNPs have been identified, only a small subset needs to be genotyped in order to accurately predict ancestry with a minimal error rate in a cost-effective manner. In this article, we compared various methods for selecting ancestry informative SNPs using simulations as well as SNP genotype data from samples of admixed populations and showed that the I_nmeasure estimates ancestry proportion (in an admixed population) with lower bias and mean square error.</p

Lawson criterion for ignition exceeded in an inertial fusion experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion