On the Computational Complexity of Vertex Integrity and Component Order Connectivity

The Weighted Vertex Integrity (wVI) problem takes as input an $n$-vertex graph $G$, a weight function $w:V(G)\to\mathbb{N}$, and an integer $p$. The task is to decide if there exists a set $X\subseteq V(G)$ such that the weight of $X$ plus the weight of a heaviest component of $G-X$ is at most $p$. Among other results, we prove that: (1) wVI is NP-complete on co-comparability graphs, even if each vertex has weight $1$; (2) wVI can be solved in $O(p^{p+1}n)$ time; (3) wVI admits a kernel with at most $p^3$ vertices. Result (1) refutes a conjecture by Ray and Deogun and answers an open question by Ray et al. It also complements a result by Kratsch et al., stating that the unweighted version of the problem can be solved in polynomial time on co-comparability graphs of bounded dimension, provided that an intersection model of the input graph is given as part of the input. An instance of the Weighted Component Order Connectivity (wCOC) problem consists of an $n$-vertex graph $G$, a weight function $w:V(G)\to \mathbb{N}$, and two integers $k$ and $l$, and the task is to decide if there exists a set $X\subseteq V(G)$ such that the weight of $X$ is at most $k$ and the weight of a heaviest component of $G-X$ is at most $l$. In some sense, the wCOC problem can be seen as a refined version of the wVI problem. We prove, among other results, that: (4) wCOC can be solved in $O(\min\{k,l\}\cdot n^3)$ time on interval graphs, while the unweighted version can be solved in $O(n^2)$ time on this graph class; (5) wCOC is W[1]-hard on split graphs when parameterized by $k$ or by $l$; (6) wCOC can be solved in $2^{O(k\log l)} n$ time; (7) wCOC admits a kernel with at most $kl(k+l)+k$ vertices. We also show that result (6) is essentially tight by proving that wCOC cannot be solved in $2^{o(k \log l)}n^{O(1)}$ time, unless the ETH fails.Comment: A preliminary version of this paper already appeared in the conference proceedings of ISAAC 201

Lithic technological responses to Late Pleistocene glacial cycling at Pinnacle Point Site 5-6, South Africa

There are multiple hypotheses for human responses to glacial cycling in the Late Pleistocene, including changes in population size, interconnectedness, and mobility. Lithic technological analysis informs us of human responses to environmental change because lithic assemblage characteristics are a reflection of raw material transport, reduction, and discard behaviors that depend on hunter-gatherer social and economic decisions. Pinnacle Point Site 5-6 (PP5-6), Western Cape, South Africa is an ideal locality for examining the influence of glacial cycling on early modern human behaviors because it preserves a long sequence spanning marine isotope stages (MIS) 5, 4, and 3 and is associated with robust records of paleoenvironmental change. The analysis presented here addresses the question, what, if any, lithic assemblage traits at PP5-6 represent changing behavioral responses to the MIS 5-4-3 interglacial-glacial cycle? It statistically evaluates changes in 93 traits with no a priori assumptions about which traits may significantly associate with MIS. In contrast to other studies that claim that there is little relationship between broad-scale patterns of climate change and lithic technology, we identified the following characteristics that are associated with MIS 4: increased use of quartz, increased evidence for outcrop sources of quartzite and silcrete, increased evidence for earlier stages of reduction in silcrete, evidence for increased flaking efficiency in all raw material types, and changes in tool types and function for silcrete. Based on these results, we suggest that foragers responded to MIS 4 glacial environmental conditions at PP5-6 with increased population or group sizes, 'place provisioning', longer and/or more intense site occupations, and decreased residential mobility. Several other traits, including silcrete frequency, do not exhibit an association with MIS. Backed pieces, once they appear in the PP5-6 record during MIS 4, persist through MIS 3. Changing paleoenvironments explain some, but not all temporal technological variability at PP5-6.Social Science and Humanities Research Council of Canada; NORAM; American-Scandinavian Foundation; Fundacao para a Ciencia e Tecnologia [SFRH/BPD/73598/2010]; IGERT [DGE 0801634]; Hyde Family Foundations; Institute of Human Origins; National Science Foundation [BCS-9912465, BCS-0130713, BCS-0524087, BCS-1138073]; John Templeton Foundation to the Institute of Human Origins at Arizona State Universit

A preliminary audit of medical and aid provision in English Rugby union clubs:compliance with Regulation 9

BackgroundGoverning bodies are largely responsible for the monitoring and management of risks associated with a safe playing environment, yet adherence to regulations is currently unknown. The aim of this study was to investigate and evaluate the current status of medical personnel, facilities, and equipment in Rugby Union clubs at regional level in England.MethodsA nationwide cross-sectional survey of 242 registered clubs was undertaken, where clubs were surveyed online on their current medical personnel, facilities, and equipment provision, according to regulation 9 of the Rugby Football Union (RFU).ResultsOverall, 91 (45. 04%) surveys were returned from the successfully contacted recipients. Of the completed responses, only 23.61% (n = 17) were found to be compliant with regulations. Furthermore, 30.56% (n = 22) of clubs were unsure if their medical personnel had required qualifications; thus, compliance could not be determined. There was a significant correlation (p = −0.029, r = 0.295) between club level and numbers of practitioners. There was no significant correlation indicated between the number of practitioners/number of teams and number of practitioners/number of players. There were significant correlations found between club level and equipment score (p = 0.003, r = −0.410), club level and automated external defibrillator (AED) access (p = 0.002, r = −0.352) and practitioner level and AED access (p = 0.0001, r = 0.404). Follow-up, thematic analysis highlighted widespread club concern around funding/cost, awareness, availability of practitioners and AED training.ConclusionThe proportion of clubs not adhering overall compliance with Regulation 9 of the RFU is concerning for player welfare, and an overhaul, nationally, is required

Evaluating anthropogenic threats to endangered killer whales to inform effective recovery plans

This is the final version of the article. Available from Springer Nature via the DOI in this record.Understanding cumulative effects of multiple threats is key to guiding effective management to conserve endangered species. The critically endangered, Southern Resident killer whale population of the northeastern Pacific Ocean provides a data-rich case to explore anthropogenic threats on population viability. Primary threats include: limitation of preferred prey, Chinook salmon; anthropogenic noise and disturbance, which reduce foraging efficiency; and high levels of stored contaminants, including PCBs. We constructed a population viability analysis to explore possible demographic trajectories and the relative importance of anthropogenic stressors. The population is fragile, with no growth projected under current conditions, and decline expected if new or increased threats are imposed. Improvements in fecundity and calf survival are needed to reach a conservation objective of 2.3% annual population growth. Prey limitation is the most important factor affecting population growth. However, to meet recovery targets through prey management alone, Chinook abundance would have to be sustained near the highest levels since the 1970s. The most optimistic mitigation of noise and contaminants would make the difference between a declining and increasing population, but would be insufficient to reach recovery targets. Reducing acoustic disturbance by 50% combined with increasing Chinook by 15% would allow the population to reach 2.3% growth

Mobile phone text message intervention to reduce binge drinking among young adults: Study protocol for a randomized controlled trial

Background: Heavy episodic (binge) drinking is common among young adults and can lead to injury and illness. Young adults who seek care in the Emergency Department (ED) may be disproportionately affected with binge drinking behavior, therefore provide an opportunity to reduce future risk through screening, brief intervention and referral to treatment (SBIRT). Mobile phone text messaging (SMS) is a common form of communication among young adults and has been shown to be effective at providing behavioral support to young adult drinkers after ED discharge. Efficacy of SMS programs to reduce binge drinking remains unknown.Methods/Design: We will conduct a three parallel arm, randomized trial. A convenience sample of adults aged 18 to 25 years attending three EDs in Pittsburgh, PA and willing to participate in the study will be screened for hazardous alcohol consumption. Participants identified as hazardous drinkers will then be allocated to either 12 weeks of weekly SMS drinking assessments with feedback (SA+F), SMS drinking assessments without feedback (SA), or a control group. Randomization will be via an independent and remote computerized randomization and will be stratified by study site. The SA+F group will be asked to provide pre-weekend drinking intention as well as post-weekend consumption via SMS and will receive feedback messages focused on health consequences of alcohol consumption, personalized normative feedback, protective drinking strategies and goal setting. Follow-up data on alcohol use and injury related to alcohol will be collected through a password-protected website three, six and nine months later. The primary outcome for the study is binge drinking days (≥4 drinks for women; ≥5 drinks for men) during the previous month, and the main secondary outcome is the proportion of participants who report any injury related to alcohol in the prior three months.Discussion: This study will test the hypothesis that a mobile phone text-messaging program will result in immediate and durable reductions in binge drinking among at-risk young adults. By testing an intervention group to an assessment-only and control group, we will be able to separate the effect of assessment reactivity. By collecting pre-weekend drinking intentions and post-weekend consumption data in the SA+F group, we will be able to better understand mechanism of change.Trial registration: Clinicaltrials.gov NCT01688245. © 2013 Suffoletto et al.; licensee BioMed Central Ltd

Creativity and Autonomy in Swarm Intelligence Systems

This work introduces two swarm intelligence algorithms -- one mimicking the behaviour of one species of ants (\emph{Leptothorax acervorum}) foraging (a `Stochastic Diffusion Search', SDS) and the other algorithm mimicking the behaviour of birds flocking (a `Particle Swarm Optimiser', PSO) -- and outlines a novel integration strategy exploiting the local search properties of the PSO with global SDS behaviour. The resulting hybrid algorithm is used to sketch novel drawings of an input image, exploliting an artistic tension between the local behaviour of the `birds flocking' - as they seek to follow the input sketch - and the global behaviour of the `ants foraging' - as they seek to encourage the flock to explore novel regions of the canvas. The paper concludes by exploring the putative `creativity' of this hybrid swarm system in the philosophical light of the `rhizome' and Deleuze's well known `Orchid and Wasp' metaphor

Effect of antiandrogen flutamide on measures of hepatic regeneration in rats

Male rat liver undergoes a process of demasculinization during hepatic regeneration following partial hepatectomy. The possibility that antiandrogens might potentiate this demasculinization process and in so doing augment the hepatic regenerative response was investigated. Adult male Wistar rats were treated with the antiandrogen flutamide (2 mg/rat/day or 5 mg/rat/day subcutaneously) or vehicle for three days prior to and daily after a 70% partial hepatectomy. At various times after hepatectomy, the liver remnants were removed and weighed. Rates of DNA and polyamine synthesis were assessed by measuring thymidine kinase and ornithine decarboxylase activities, respectively. Hepatic estrogen receptor status and the activity of alcohol dehydrogenase, an androgen-sensitive protein, were measured. Prior to surgery, the administration of 5 mg/day flutamide reduced the hepatic cytosolic androgen receptor activity by 98% and hepatic cytosolic estrogen receptor content by 92% compared to that present in vehicle-treated controls. After hepatectomy, however, all differences in sex hormone receptor activity between the treatment groups were abolished. The rate of liver growth after partial hepatectomy in the three groups was identical. Moreover, hepatectomy-induced increases in ornithine decarboxylase activity and thymidine kinase activity were comparable. These data demonstrate that, although flutamide administration initially alters the sex hormone receptor status of the liver, these affects have no effect on the hepatic regenerative response following a partial hepatectomy. © 1989 Plenum Publishing Corporation