Showing papers by "Dalhousie University published in 2011"

How Many Species Are There on Earth and in the Ocean

Abstract: The diversity of life is one of the most striking aspects of our planet; hence knowing how many species inhabit Earth is among the most fundamental questions in science. Yet the answer to this question remains enigmatic, as efforts to sample the world's biodiversity to date have been limited and thus have precluded direct quantification of global species richness, and because indirect estimates rely on assumptions that have proven highly controversial. Here we show that the higher taxonomic classification of species (i.e., the assignment of species to phylum, class, order, family, and genus) follows a consistent and predictable pattern from which the total number of species in a taxonomic group can be estimated. This approach was validated against well-known taxa, and when applied to all domains of life, it predicts ∼8.7 million (±1.3 million SE) eukaryotic species globally, of which ∼2.2 million (±0.18 million SE) are marine. In spite of 250 years of taxonomic classification and over 1.2 million species already catalogued in a central database, our results suggest that some 86% of existing species on Earth and 91% of species in the ocean still await description. Renewed interest in further exploration and taxonomy is required if this significant gap in our knowledge of life on Earth is to be closed.

The epidemiology of chronic pain in children and adolescents revisited: A systematic review

Abstract: Chronic and recurrent pain not associated with a disease is very common in childhood and adolescence, but studies of pain prevalence have yielded inconsistent findings. This systematic review examined studies of chronic and recurrent pain prevalence to provide updated aggregated prevalence rates. The review also examined correlates of chronic and recurrent pain such as age, sex, and psychosocial functioning. Studies of pain prevalence rates in children and adolescents published in English or French between 1991 and 2009 were identified using EMBASE, Medline, CINAHL, and PsycINFO databases. Of 185 published papers yielded by the search, 58 met inclusion criteria and were reviewed, and 41 were included in the review. Two independent reviewers screened papers for inclusion, extracted data, and assessed the quality of studies. Prevalence rates ranged substantially, and were as follows: headache: 8–83%; abdominal pain: 4–53%; back pain: 14–24%; musculoskeletal pain: 4–40%; multiple pains: 4–49%; other pains: 5–88%. Pain prevalence rates were generally higher in girls and increased with age for most pain types. Lower socioeconomic status was associated with higher pain prevalence especially for headache. Most studies did not meet quality criteria.

Recurrence risk for autism spectrum disorders: a Baby Siblings Research Consortium study.

Abstract: The recurrence risk of autism spectrum disorders (ASD) is estimated to be between 3% and 10%, but previous research was limited by small sample sizes and biases related to ascertainment, reporting, and stoppage factors. This study used prospective methods to obtain an updated estimate of sibling recurrence risk for ASD. METHODS: A prospective longitudinal study of infants at risk for ASD was conducted by a multisite international network, the Baby Siblings Research Consortium. Infants (n 664) with an older biological sibling with ASD were followed from early in life to 36 months, when they were classified as having or not having ASD. An ASD classification required surpassing the cutoff of the Autism Diagnostic Observation Schedule and receiving a clinical diagnosis from an expert clinician. RESULTS: A total of 18.7% of the infants developed ASD. Infant gender and the presence of 1 older affected sibling were significant predic- tors of ASD outcome, and there was an almost threefold increase in risk for male subjects and an additional twofold increase in risk if there was 1 older affected sibling. The age of the infant at study enrollment, the gender and functioning level of the infant's older sib- ling, and other demographic factors did not predict ASD outcome. CONCLUSIONS: The sibling recurrence rate of ASD is higher than sug- gested by previous estimates. The size of the current sample and pro- spective nature of data collection minimized many limitations of previ- ous studies of sibling recurrence. Clinical implications, including genetic counseling, are discussed. Pediatrics 2011;128:e000

The social ecology of resilience: addressing contextual and cultural ambiguity of a nascent construct.

Abstract: More than two decades after E. E. Werner and R. S. Smith (1982), N. Garmezy (1983), and M. Rutter (1987) published their research on protective mechanisms and processes that are most likely to foster resilience, ambiguity continues regarding how to define and operationalize positive development under adversity. This article argues that, because resilience occurs even when risk factors are plentiful, greater emphasis needs to be placed on the role social and physical ecologies play in positive developmental outcomes when individuals encounter significant amounts of stress. Four principles are presented as the basis for an ecological interpretation of the resilience construct: decentrality, complexity, atypicality, and cultural relativity. These 4 principles, and the research upon which they are based, inform a definition of resilience that emphasizes the environmental antecedents of positive growth. This framework can guide future theory development, research, and the design of interventions that promote well-being among populations who experience environments that inhibit resilience-promoting processes.

Tracking apex marine predator movements in a dynamic ocean

Abstract: Pelagic marine predators face unprecedented challenges and uncertain futures. Overexploitation and climate variability impact the abundance and distribution of top predators in ocean ecosystems. Improved understanding of ecological patterns, evolutionary constraints and ecosystem function is critical for preventing extinctions, loss of biodiversity and disruption of ecosystem services. Recent advances in electronic tagging techniques have provided the capacity to observe the movements and long-distance migrations of animals in relation to ocean processes across a range of ecological scales. Tagging of Pacific Predators, a field programme of the Census of Marine Life, deployed 4,306 tags on 23 species in the North Pacific Ocean, resulting in a tracking data set of unprecedented scale and species diversity that covers 265,386 tracking days from 2000 to 2009. Here we report migration pathways, link ocean features to multispecies hotspots and illustrate niche partitioning within and among congener guilds. Our results indicate that the California Current large marine ecosystem and the North Pacific transition zone attract and retain a diverse assemblage of marine vertebrates. Within the California Current large marine ecosystem, several predator guilds seasonally undertake north-south migrations that may be driven by oceanic processes, species-specific thermal tolerances and shifts in prey distributions. We identify critical habitats across multinational boundaries and show that top predators exploit their environment in predictable ways, providing the foundation for spatial management of large marine ecosystems.

Effect of nesiritide in patients with acute decompensated heart failure.

Abstract: A b s t r ac t Background Nesiritide is approved in the United States for early relief of dyspnea in patients with acute heart failure. Previous meta-analyses have raised questions regarding renal toxicity and the mortality associated with this agent. Methods We randomly assigned 7141 patients who were hospitalized with acute heart failure to receive either nesiritide or placebo for 24 to 168 hours in addition to standard care. Coprimary end points were the change in dyspnea at 6 and 24 hours, as measured on a 7-point Likert scale, and the composite end point of rehospitalization for heart failure or death within 30 days. Results Patients randomly assigned to nesiritide, as compared with those assigned to placebo, more frequently reported markedly or moderately improved dyspnea at 6 hours (44.5% vs. 42.1%, P = 0.03) and 24 hours (68.2% vs. 66.1%, P = 0.007), but the prespecified level for significance (P≤0.005 for both assessments or P≤0.0025 for either) was not met. The rate of rehospitalization for heart failure or death from any cause within 30 days was 9.4% in the nesiritide group versus 10.1% in the placebo group (absolute difference, −0.7 percentage points; 95% confidence interval [CI], −2.1 to 0.7; P = 0.31). There were no significant differences in rates of death from any cause at 30 days (3.6% with nesiritide vs. 4.0% with placebo; absolute difference, −0.4 percentage points; 95% CI, −1.3 to 0.5) or rates of worsening renal function, defined by more than a 25% decrease in the estimated glomerular filtration rate (31.4% vs. 29.5%; odds ratio, 1.09; 95% CI, 0.98 to 1.21; P = 0.11). Conclusions Nesiritide was not associated with an increase or a decrease in the rate of death and rehospitalization and had a small, nonsignificant effect on dyspnea when used in combination with other therapies. It was not associated with a worsening of renal function, but it was associated with an increase in rates of hypotension. On the basis of these results, nesiritide cannot be recommended for routine use in the broad population of patients with acute heart failure. (Funded by Scios; ClinicalTrials.gov number, NCT00475852.)

Coronary-Artery Bypass Surgery in Patients with Left Ventricular Dysfunction

Abstract: The primary outcome occurred in 244 patients (41%) in the medical-therapy group and 218 (36%) in the CABG group (hazard ratio with CABG, 0.86; 95% confidence interval [CI], 0.72 to 1.04; P = 0.12). A total of 201 patients (33%) in the medicaltherapy group and 168 (28%) in the CABG group died from an adjudicated cardiovascular cause (hazard ratio with CABG, 0.81; 95% CI, 0.66 to 1.00; P = 0.05). Death from any cause or hospitalization for cardiovascular causes occurred in 411 patients (68%) in the medical-therapy group and 351 (58%) in the CABG group (hazard ratio with CABG, 0.74; 95% CI, 0.64 to 0.85; P<0.001). By the end of the followup period (median, 56 months), 100 patients in the medical-therapy group (17%) underwent CABG, and 555 patients in the CABG group (91%) underwent CABG. Conclusions In this randomized trial, there was no significant difference between medical therapy alone and medical therapy plus CABG with respect to the primary end point of death from any cause. Patients assigned to CABG, as compared with those assigned to medical therapy alone, had lower rates of death from cardiovascular causes and of death from any cause or hospitalization for cardiovascular causes. (Funded by the National Heart, Lung, and Blood Institute and Abbott Laboratories; STICH ClinicalTrials.gov number, NCT00023595.)

The Selaginella genome identifies genetic changes associated with the evolution of vascular plants.

Abstract: Vascular plants appeared ~410 million years ago, then diverged into several lineages of which only two survive: the euphyllophytes (ferns and seed plants) and the lycophytes. We report here the genome sequence of the lycophyte Selaginella moellendorffii (Selaginella), the first nonseed vascular plant genome reported. By comparing gene content in evolutionarily diverse taxa, we found that the transition from a gametophyte- to a sporophyte-dominated life cycle required far fewer new genes than the transition from a nonseed vascular to a flowering plant, whereas secondary metabolic genes expanded extensively and in parallel in the lycophyte and angiosperm lineages. Selaginella differs in posttranscriptional gene regulation, including small RNA regulation of repetitive elements, an absence of the trans-acting small interfering RNA pathway, and extensive RNA editing of organellar genes.

Optimal Distributed Generation Allocation and Sizing in Distribution Systems via Artificial Bee Colony Algorithm

Abstract: Distributed generation (DG) has been utilized in some electric power networks. Power loss reduction, environmental friendliness, voltage improvement, postponement of system upgrading, and increasing reliability are some advantages of DG-unit application. This paper presents a new optimization approach that employs an artificial bee colony (ABC) algorithm to determine the optimal DG-unit's size, power factor, and location in order to minimize the total system real power loss. The ABC algorithm is a new metaheuristic, population-based optimization technique inspired by the intelligent foraging behavior of the honeybee swarm. To reveal the validity of the ABC algorithm, sample radial distribution feeder systems are examined with different test cases. Furthermore, the results obtained by the proposed ABC algorithm are compared with those attained via other methods. The outcomes verify that the ABC algorithm is efficient, robust, and capable of handling mixed integer nonlinear optimization problems. The ABC algorithm has only two parameters to be tuned. Therefore, the updating of the two parameters towards the most effective values has a higher likelihood of success than in other competing metaheuristic methods.

Are there bilingual advantages on nonlinguistic interference tasks? Implications for the plasticity of executive control processes

Abstract: It has been proposed that the unique need for early bilinguals to manage multiple languages while their executive control mechanisms are developing might result in long-term cognitive advantages on inhibitory control processes that generalize beyond the language domain. We review the empirical data from the literature on nonlinguistic interference tasks to assess the validity of this proposed bilingual inhibitory control advantage. Our review of these findings reveals that the bilingual advantage on conflict resolution, which by hypothesis is mediated by inhibitory control, is sporadic at best, and in some cases conspicuously absent. A robust finding from this review is that bilinguals typically outperform monolinguals on both compatible and incompatible trials, often by similar magnitudes. Together, these findings suggest that bilinguals do enjoy a more widespread cognitive advantage (a bilingual executive processing advantage) that is likely observable on a variety of cognitive assessment tools but that, somewhat ironically, is most often not apparent on traditional assays of nonlinguistic inhibitory control processes.

Pi and the AGM: A Study in Analytic Number Theory and Computational Complexity

Abstract: Complete Elliptic Integrals and the Arithmetic-Geometric Mean Iteration. Theta Functions and the Arithmetic-Geometric Mean Iteration. Jacobi's Triple-Product and Some Number Theoretic Applications. Higher Order Transformations. Modular Equations and Algebraic Approximations to pi. The Complexity of Algebraic Functions. Algorithms for the Elementary Functions. General Means and Iterations. Some Additional Applications. Other Approaches to the Elementary Functions. Pi. Bibliography. Symbol List. Index.

Imagining Twitter as an Imagined Community

Abstract: The notion of “community” has often been caught between concrete social relationships and imagined sets of people perceived to be similar. The rise of the Internet has refocused our attention on this ongoing tension. The Internet has enabled people who know each other to use social media, from e-mail to Facebook, to interact without meeting physically. Into this mix came Twitter, an asymmetric microblogging service: If you follow me, I do not have to follow you. This means that connections on Twitter depend less on in-person contact, as many users have more followers than they know. Yet there is a possibility that Twitter can form the basis of interlinked personal communities—and even of a sense of community. This analysis of one person’s Twitter network shows that it is the basis for a real community, even though Twitter was not designed to support the development of online communities. Studying Twitter is useful for understanding how people use new communication technologies to form new social connections and maintain existing ones.

Assessing Resilience Across Cultures Using Mixed Methods: Construction of the Child and Youth Resilience Measure:

Abstract: An international team of investigators in 11 countries have worked collaboratively to develop a culturally and contextually relevant measure of youth resilience, the Child and Youth Resilience Measure (CYRM-28). The team used a mixed methods design that facilitated understanding of both common and unique aspects of resilience across cultures. Quantitative and qualitative stages to its development ensure the CYRM-28 has good content-related validity across research sites. Crossover comparison analyses of the findings from the quantitative administration of the pilot measure with 1,451 youth and qualitative interviews with 89 youth support the CYRM-28 as a culturally sensitive measure of youth resilience. The implications of this mixed methods approach to the development of measures for cross-cultural research are discussed.

Aldehyde dehydrogenase: Its role as a cancer stem cell marker comes down to the specific isoform

Abstract: Recent evidence suggests that enhanced aldehyde dehydrogenase (ALDH) activity is a hallmark of cancer stem cells (CSC) measurable by the aldefluor assay. ALDH1A1, one of 19 ALDH isoforms expressed in humans, was generally believed to be responsible for the ALDH activity of CSCs. More recently, experiments with murine hematopoietic stem cells, murine progenitor pancreatic cells, and human breast CSCs indicate that other ALDH isoforms, particularly ALDH1A3, significantly contribute to aldefluor positivity, which may be tissue and cancer specific. Therefore, potential prognostic application involving the use of CSC prevalence in tumor tissue to predict patient outcome requires the identification and quantification of specific ALDH isoforms. Herein we review the suggested roles of ALDH in CSC biology and the immunohistological studies testing the potential application of ALDH isoforms as novel cancer prognostic indicators.

Theoretical perspectives in medical education: past experience and future possibilities.

Abstract: CONTEXT Pedagogical practices reflect theoretical perspectives and beliefs that people hold about learning. Perspectives on learning are important because they influence almost all decisions about curriculum, teaching and assessment. Since Flexner's 1910 report on medical education, significant changes in perspective have been evident. Yet calls for major reform of medical education may require a broader conceptualisation of the educational process. PAST AND CURRENT PERSPECTIVES Medical education has emerged as a complex transformative process of socialisation into the culture and profession of medicine. Theory and research, in medical education and other fields, have contributed important understanding. Learning theories arising from behaviourist, cognitivist, humanist and social learning traditions have guided improvements in curriculum design and instruction, understanding of memory, expertise and clinical decision making, and self-directed learning approaches. Although these remain useful, additional perspectives which recognise the complexity of education that effectively fosters the development of knowledge, skills and professional identity are needed. FUTURE PERSPECTIVES Socio-cultural learning theories, particularly situated learning, and communities of practice offer a useful theoretical perspective. They view learning as intimately tied to context and occurring through participation and active engagement in the activities of the community. Legitimate peripheral participation describes learners' entry into the community. As learners gain skill, they assume more responsibility and move more centrally. The community, and the people and artefacts within it, are all resources for learning. Learning is both collective and individual. Social cognitive theory offers a complementary perspective on individual learning. Situated learning allows the incorporation of other learning perspectives and includes workplace learning and experiential learning. Viewing medical education through the lens of situated learning suggests teaching and learning approaches that maximise participation and build on community processes to enhance both collective and individual learning.

Depth-dependent extension, two-stage breakup and cratonic underplating at rifted margins

Abstract: Huismans and Beaumont use dynamical models to demonstrate that typical continental margins such as the Iberia–Newfoundland conjugates and the central South Atlantic margins are opposite end members. In the first type, depth-dependent extension results in crustal necking and break-up before mantle lithosphere break-up, whereas in the latter type, the converse is true. These two-layer, two-stage break-up behaviours explain a number of discrepancies between observations and earlier models of continental breakup. Uniform lithospheric extension1 predicts basic properties of non-volcanic rifted margins but fails to explain other important characteristics2,3. Significant discrepancies are observed at ‘type I’ margins (such as the Iberia–Newfoundland conjugates), where large tracts of continental mantle lithosphere are exposed at the sea floor4, and ‘type II’ margins (such as some ultrawide central South Atlantic margins), where thin continental crust spans wide regions below which continental lower crust and mantle lithosphere have apparently been removed5,6. Neither corresponds to uniform extension. Instead, either crust or mantle lithosphere has been preferentially removed. Using dynamical models, we demonstrate that these margins are opposite end members: in type I, depth-dependent extension results in crustal-necking breakup before mantle-lithosphere breakup and in type II, the converse is true. These two-layer, two-stage breakup behaviours explain the discrepancies and have implications for the styles of the associated sedimentary basins. Laterally flowing lower-mantle cratonic lithosphere may underplate some type II margins, thereby contributing to their anomalous characteristics.

Changes in relative fitness and frailty across the adult lifespan: evidence from the Canadian National Population Health Survey

Abstract: Background The prevalence of frailty increases with age in older adults, but frailty is largely unreported for younger adults, where its associated risk is less clear. Furthermore, less is known about how frailty changes over time among younger adults. We estimated the prevalence and outcomes of frailty, in relation to accumulation of deficits, across the adult lifespan. Methods We analyzed data for community-dwelling respondents (age 15–102 years at baseline) to the longitudinal component of the National Population Health Survey, with seven two-year cycles, beginning 1994–1995. The outcomes were death, use of health services and change in health status, measured in terms of a Frailty Index constructed from 42 self-reported health variables. Results The sample consisted of 14 713 respondents (54.2% women). Vital status was known for more than 99% of the respondents. The prevalence of frailty increased with age, from 2.0% (95% confidence interval [CI] 1.7%–2.4%) among those younger than 30 years to 22.4% (95% CI 19.0%–25.8%) for those older than age 65, including 43.7% (95% CI 37.1%–50.8%) for those 85 and older. At all ages, the 160-month mortality rate was lower among relatively fit people than among those who were frail (e.g., 2% v. 16% at age 40; 42% v. 83% at age 75 or older). These relatively fit people tended to remain relatively fit over time. Relative to all other groups, a greater proportion of the most frail people used health services at baseline (28.3%, 95% CI 21.5%–35.5%) and at each follow-up cycle (26.7%, 95% CI 15.4%–28.0%). Interpretation Deficits accumulated with age across the adult spectrum. At all ages, a higher Frailty Index was associated with higher mortality and greater use of health care services. At younger ages, recovery to the relatively fittest state was common, but the chance of complete recovery declined with age.

An introduction to immunology and immunopathology

Abstract: In basic terms, the immune system has two lines of defense: innate immunity and adaptive immunity. Innate immunity is the first immunological, non-specific (antigen-independent) mechanism for fighting against an intruding pathogen. It is a rapid immune response, occurring within minutes or hours after aggression, that has no immunologic memory. Adaptive immunity, on the other hand, is antigen-dependent and antigen-specific; it has the capacity for memory, which enables the host to mount a more rapid and efficient immune response upon subsequent exposure to the antigen. There is a great deal of synergy between the adaptive immune system and its innate counterpart, and defects in either system can provoke illness or disease, such as autoimmune diseases, immunodeficiency disorders and hypersensitivity reactions. This article provides a practical overview of innate and adaptive immunity, and describes how these host defense mechanisms are involved in both health and illness.

Tumor Cell Marker PVRL4 (Nectin 4) Is an Epithelial Cell Receptor for Measles Virus

Abstract: Vaccine and laboratory adapted strains of measles virus can use CD46 as a receptor to infect many human cell lines However, wild type isolates of measles virus cannot use CD46, and they infect activated lymphocytes, dendritic cells, and macrophages via the receptor CD150/SLAM Wild type virus can also infect epithelial cells of the respiratory tract through an unidentified receptor We demonstrate that wild type measles virus infects primary airway epithelial cells grown in fetal calf serum and many adenocarcinoma cell lines of the lung, breast, and colon Transfection of non-infectable adenocarcinoma cell lines with an expression vector encoding CD150/SLAM rendered them susceptible to measles virus, indicating that they were virus replication competent, but lacked a receptor for virus attachment and entry Microarray analysis of susceptible versus non-susceptible cell lines was performed, and comparison of membrane protein gene transcripts produced a list of 11 candidate receptors Of these, only the human tumor cell marker PVRL4 (Nectin 4) rendered cells amenable to measles virus infections Flow cytometry confirmed that PVRL4 is highly expressed on the surfaces of susceptible lung, breast, and colon adenocarcinoma cell lines Measles virus preferentially infected adenocarcinoma cell lines from the apical surface, although basolateral infection was observed with reduced kinetics Confocal immune fluorescence microscopy and surface biotinylation experiments revealed that PVRL4 was expressed on both the apical and basolateral surfaces of these cell lines Antibodies and siRNA directed against PVRL4 were able to block measles virus infections in MCF7 and NCI-H358 cancer cells A virus binding assay indicated that PVRL4 was a bona fide receptor that supported virus attachment to the host cell Several strains of measles virus were also shown to use PVRL4 as a receptor Measles virus infection reduced PVRL4 surface expression in MCF7 cells, a property that is characteristic of receptor-associated viral infections

Aldehyde Dehydrogenase Activity of Breast Cancer Stem Cells Is Primarily Due To Isoform ALDH1A3 and Its Expression Is Predictive of Metastasis

Abstract: Cancer stem cells (CSCs) are proposed to initiate cancer and propagate metastasis. Breast CSCs identified by aldehyde dehydrogenase (ALDH) activity are highly tumorigenic in xenograft models. However, in patient breast tumor immunohistological studies, where CSCs are identified by expression of ALDH isoform ALDH1A1, CSC prevalence is not correlative with metastasis, raising some doubt as to the role of CSCs in cancer. We characterized the expression of all 19 ALDH isoforms in patient breast tumor CSCs and breast cancer cell lines by total genome microarray expression analysis, immunofluorescence protein expression studies, and quantitative polymerase chain reaction. These studies revealed that ALDH activity of patient breast tumor CSCs and cell lines correlates best with expression of another isoform, ALDH1A3, not ALDH1A1. We performed shRNA knockdown experiments of the various ALDH isoforms and found that only ALDH1A3 knockdown uniformly reduced ALDH activity of breast cancer cells. Immunohistological studies with fixed patient breast tumor samples revealed that ALDH1A3 expression in patient breast tumors correlates significantly with tumor grade, metastasis, and cancer stage. Our results, therefore, identify ALDH1A3 as a novel CSC marker with potential clinical prognostic applicability, and demonstrate a clear correlation between CSC prevalence and the development of metastatic breast cancer. STEM CELLS 2011;29:32–45

Depth-dependent extension, two-stage breakup and cratonic underplating at rifted margins

Abstract: Huismans and Beaumont use dynamical models to demonstrate that typical continental margins such as the Iberia–Newfoundland conjugates and the central South Atlantic margins are opposite end members. In the first type, depth-dependent extension results in crustal necking and break-up before mantle lithosphere break-up, whereas in the latter type, the converse is true. These two-layer, two-stage break-up behaviours explain a number of discrepancies between observations and earlier models of continental breakup. Uniform lithospheric extension1 predicts basic properties of non-volcanic rifted margins but fails to explain other important characteristics2,3. Significant discrepancies are observed at ‘type I’ margins (such as the Iberia–Newfoundland conjugates), where large tracts of continental mantle lithosphere are exposed at the sea floor4, and ‘type II’ margins (such as some ultrawide central South Atlantic margins), where thin continental crust spans wide regions below which continental lower crust and mantle lithosphere have apparently been removed5,6. Neither corresponds to uniform extension. Instead, either crust or mantle lithosphere has been preferentially removed. Using dynamical models, we demonstrate that these margins are opposite end members: in type I, depth-dependent extension results in crustal-necking breakup before mantle-lithosphere breakup and in type II, the converse is true. These two-layer, two-stage breakup behaviours explain the discrepancies and have implications for the styles of the associated sedimentary basins. Laterally flowing lower-mantle cratonic lithosphere may underplate some type II margins, thereby contributing to their anomalous characteristics.

The Game of Cops and Robbers on Graphs

Abstract: This book is the first and only one of its kind on the topic of Cops and Robbers games, and more generally, on the field of vertex pursuit games on graphs The book is written in a lively and highly readable fashion, which should appeal to both senior undergraduates and experts in the field (and everyone in between) One of the main goals of the book is to bring together the key results in the field; as such, it presents structural, probabilistic, and algorithmic results on Cops and Robbers games Several recent and new results are discussed, along with a comprehensive set of references The book is suitable for self-study or as a textbook, owing in part to the over 200 exercises The reader will gain insight into all the main directions of research in the field and will be exposed to a number of open problems

Organic condensation: a vital link connecting aerosol formation to cloud condensation nuclei (CCN) concentrations

Abstract: Atmospheric aerosol particles influence global climate as well as impair air quality through their effects on atmospheric visibility and human health Ultrafine (

Global Human Footprint on the Linkage between Biodiversity and Ecosystem Functioning in Reef Fishes

Abstract: Difficulties in scaling up theoretical and experimental results have raised controversy over the consequences of biodiversity loss for the functioning of natural ecosystems. Using a global survey of reef fish assemblages, we show that in contrast to previous theoretical and experimental studies, ecosystem functioning (as measured by standing biomass) scales in a nonsaturating manner with biodiversity (as measured by species and functional richness) in this ecosystem. Our field study also shows a significant and negative interaction between human population density and biodiversity on ecosystem functioning (i.e., for the same human density there were larger reductions in standing biomass at more diverse reefs). Human effects were found to be related to fishing, coastal development, and land use stressors, and currently affect over 75% of the world’s coral reefs. Our results indicate that the consequences of biodiversity loss in coral reefs have been considerably underestimated based on existing knowledge and that reef fish assemblages, particularly the most diverse, are greatly vulnerable to the expansion and intensity of anthropogenic stressors in coastal areas.

Neurocognitive Signs in Prodromal Huntington Disease

Abstract: Huntington disease (HD) is a progressive, fatal, autosomal dominant neurodegenerative disease that primarily affects movement, cognition, and psychiatric functions. Diagnosis of HD is based on the presence of unequivocal motor signs of HD, in conjunction with a positive genetic test for the HD CAG expansion or a confirmed family history of HD. Most people with the HD gene appear healthy throughout their youth and early adulthood, and then gradually develop signs and symptoms of HD, often leading to a diagnosis in middle age. The age of diagnosis varies in accordance with the number of CAG repeats on the expanded allele, although there is also substantial individual variability not accounted for by this genetic factor (Andrew et al., 1993; Gusella, MacDonald, Ambrose, & Duyao, 1993). A growing community of researchers is directing efforts at finding treatments to delay onset or slow the progression of early pathological changes in an attempt to reduce the tremendous personal and social costs of HD. Finding effective therapeutic or preventive treatments for HD depends critically on the ability to reliably and sensitively measure clinical signs of disease. Cognitive measures have excellent potential both for identifying individuals beginning to show subtle signs prior to the diagnosis of HD who might be suitable for clinical trials, and as sensitive outcome measures in HD trials. Cognition is an important target for therapeutic trials because even subtle cognitive changes can affect functional abilities like work performance, driving, and financial management. Cognition is actively studied in the HD prodrome, with more than 150 empirical reports of neurocognitive function published since the genetic mutation for HD was identified in 1993. In early studies, the evidence of cognitive dysfunction was inconsistent. But more recent, adequately powered studies have revealed that people with the HD prodrome have poorer performance on measures of attention, working memory, processing speed, psychomotor functions, episodic memory, emotion processing, sensory-perceptual functions, and executive functions (Johnson et al., 2007; Kirkwood et al., 2000; Paulsen et al., 2006a; Paulsen et al., 2008; Paulsen et al., 2001; Pirogovsky et al., 2007; e.g., Stout et al., 2007). The use of cognitive measures in clinical trials requires a substantial knowledge base, indicating when in the HD prodrome cognitive changes can be reliably detected, and which measures show adequate sensitivity. The PREDICT-HD study was designed to address these questions. PREDICT-HD is a 31-site international study of potential clinical and biological markers of HD in individuals with the CAG-expansion for HD, but who did not meet criteria based on motor impairment for diagnosis at the time of enrolment. The PREDICT-HD cohort is large, with more than 700 non-diagnosed CAG-expanded (prodromal) participants. For each participant, age-conditioned estimates of time to onset of motor disease were derived using a survival analysis regression equation based on CAG repeat length (Langbehn et al., 2004). Estimated time to motor disease onset in the sample varies from 5 to 25 years. The size and diversity of this sample makes it possible to stratify participants based on their estimated proximities to diagnosis, allowing an estimation of when, in the extended period leading up to HD diagnosis, cognitive signs can be detected, and which cognitive measures appear to have the most promise for detecting change in longitudinal studies. We report findings based on three stratified prodromal HD groups, a far from diagnosis group (FAR) estimated to be more than 15 years from diagnosis, a middle group, estimated to be between 9 and 15 years from diagnosis (MID), and a near diagnosis group, estimated to be less than 9 years from diagnosis (NEAR). For each of these groups compared to controls, we computed effect sizes for individual cognitive measures, allowing a direct comparison of all the tasks in our cognitive assessment. This allows a determination of which tasks are most adversely affected during the HD prodrome, and an upper-limit estimate of how early in the prodromal phase significant effects could be detected (Paulsen et al., 2008). Additionally, we examined the associations between cognitive findings and results of the clinical motor examination, which also reveals subtle signs prior to diagnosis (Biglan et al., 2009). Thus, this study provides a comprehensive depiction of the cognitive prodrome for HD.

Recovery of marine animal populations and ecosystems

Abstract: Many marine populations and ecosystems have experienced strong historical depletions, yet reports of recoveries are increasing. Here, we review the growing research on marine recoveries to reveal how common recovery is, its magnitude, timescale and major drivers. Overall, 10–50% of depleted populations and ecosystems show some recovery, but rarely to former levels of abundance. In addition, recovery can take many decades for long-lived species and complex ecosystems. Major drivers of recovery include the reduction of human impacts, especially exploitation, habitat loss and pollution, combined with favorable life-history and environmental conditions. Awareness, legal protection and enforcement of management plans are also crucial. Learning from historical recovery successes and failures is essential for implementing realistic conservation goals and promising management strategies.

Cannabinoids for treatment of chronic non-cancer pain; a systematic review of randomized trials

Abstract: Effective therapeutic options for patients living with chronic pain are limited. The pain relieving effect of cannabinoids remains unclear. A systematic review of randomized controlled trials (RCTs) examining cannabinoids in the treatment of chronic non-cancer pain was conducted according to the PRISMA statement update on the QUORUM guidelines for reporting systematic reviews that evaluate health care interventions. Cannabinoids studied included smoked cannabis, oromucosal extracts of cannabis based medicine, nabilone, dronabinol and a novel THC analogue. Chronic non-cancer pain conditions included neuropathic pain, fibromyalgia, rheumatoid arthritis, and mixed chronic pain. Overall the quality of trials was excellent. Fifteen of the eighteen trials that met the inclusion criteria demonstrated a significant analgesic effect of cannabinoid as compared with placebo and several reported significant improvements in sleep. There were no serious adverse effects. Adverse effects most commonly reported were generally well tolerated, mild to moderate in severity and led to withdrawal from the studies in only a few cases. Overall there is evidence that cannabinoids are safe and modestly effective in neuropathic pain with preliminary evidence of efficacy in fibromyalgia and rheumatoid arthritis. The context of the need for additional treatments for chronic pain is reviewed. Further large studies of longer duration examining specific cannabinoids in homogeneous populations are required.