Lorentzian and Euclidean Quantum Gravity - Analytical and Numerical Results

We review some recent attempts to extract information about the nature of quantum gravity, with and without matter, by quantum field theoretical methods. More specifically, we work within a covariant lattice approach where the individual space-time geometries are constructed from fundamental simplicial building blocks, and the path integral over geometries is approximated by summing over a class of piece-wise linear geometries. This method of ``dynamical triangulations'' is very powerful in 2d, where the regularized theory can be solved explicitly, and gives us more insights into the quantum nature of 2d space-time than continuum methods are presently able to provide. It also allows us to establish an explicit relation between the Lorentzian- and Euclidean-signature quantum theories. Analogous regularized gravitational models can be set up in higher dimensions. Some analytic tools exist to study their state sums, but, unlike in 2d, no complete analytic solutions have yet been constructed. However, a great advantage of our approach is the fact that it is well-suited for numerical simulations. In the second part of this review we describe the relevant Monte Carlo techniques, as well as some of the physical results that have been obtained from the simulations of Euclidean gravity. We also explain why the Lorentzian version of dynamical triangulations is a promising candidate for a non-perturbative theory of quantum gravity.Comment: 69 pages, 16 figures, references adde

CRPV Genomes with Synonymous Codon Optimizations in the CRPV E7 Gene Show Phenotypic Differences in Growth and Altered Immunity upon E7 Vaccination

Papillomaviruses use rare codons relative to their hosts. Recent studies have demonstrated that synonymous codon changes in viral genes can lead to increased protein production when the codons are matched to those of cells in which the protein is being expressed. We theorized that the immunogenicity of the virus would be enhanced by matching codons of selected viral genes to those of the host. We report here that synonymous codon changes in the E7 oncogene are tolerated in the context of the cottontail rabbit papillomavirus (CRPV) genome. Papilloma growth rates differ depending upon the changes made indicating that synonymous codons are not necessarily neutral. Immunization with wild type E7 DNA yielded significant protection from subsequent challenge by both wild type and codon-modified genomes. The reduction in growth was most dramatic with the genome containing the greatest number of synonymous codon changes

Population size and decadal trends of three penguin species nesting at Signy Island, South Orkney Islands

We report long-term changes in population size of three species of sympatrically breeding pygoscelid penguins: Adélie (Pygoscelis adeliae), chinstrap (Pygoscelis antarctica) and gentoo (Pygoscelis papua ellsworthii) over a 38 year period at Signy Island, South Orkney Islands, based on annual counts from selected colonies and decadal all-island systematic counts of occupied nests. Comparing total numbers of breeding pairs over the whole island from 1978/79 to 2015/16 revealed varying fortunes: gentoo penguin pairs increased by 255%, (3.5% per annum), chinstrap penguins declined by 68% (-3.6% per annum) and Adélie penguins declined by 42% (-1.5% per annum). The chinstrap population has declined steadily over the last four decades. In contrast, Adélie and gentoo penguins have experienced phases of population increase and decline. Annual surveys of selected chinstrap and Adélie colonies produced similar trends from those revealed by island-wide surveys, allowing total island population trends to be inferred relatively well. However, while the annual colony counts of chinstrap and Adélie penguins showed a trend consistent in direction with the results from all-island surveys, the magnitude of estimated population change was markedly different between colony wide and all island counts. Annual population patterns suggest that pair numbers in the study areas partly reflect immigration and emigration of nesting birds between different parts of the island. Breeding success for all three species remained broadly stable over time in the annually monitored colonies. Breeding success rates in gentoo and chinstrap penguins were strongly correlated, despite the differing trends in population size. This study shows the importance of effective, standardised monitoring to accurately determine long-term population trajectories. Our results indicate significant declines in the Adélie and chinstrap penguin populations at Signy Island over the last five decades, and a gradual increase in gentoo breeding pairs

Alcohol, binge drinking and associated mental health problems in young urban Chileans

OBJECTIVE: To explore the link between alcohol use, binge drinking and mental health problems in a representative sample of adolescent and young adult Chileans. METHODS: Age and sex-adjusted Odds Ratios (OR) for four mental wellbeing measures were estimated with separate conditional logistic regression models for adolescents aged 15-20 years, and young adults aged 21-25 years, using population-based estimates of alcohol use prevalence rates from the Chilean National Health Survey 2010. RESULTS: Sixty five per cent of adolescents and 85% of young adults reported drinking alcohol in the last year and of those 83% per cent of adolescents and 86% of young adults reported binge drinking in the previous month. Adolescents who reported binging alcohol were also more likely, compared to young adults, to report being always or almost always depressed (OR 12.97 [95% CI, 1.86-19.54]) or to feel very anxious in the last month (OR 9.37 [1.77-19.54]). Adolescent females were more likely to report poor life satisfaction in the previous year than adolescent males (OR 8.50 [1.61-15.78]), feel always or almost always depressed (OR 3.41 [1.25-9.58]). Being female was also associated with a self-reported diagnosis of depression for both age groups (adolescents, OR 4.74 [1.49-15.08] and young adults, OR 4.08 [1.65-10.05]). CONCLUSION: Young people in Chile self-report a high prevalence of alcohol use, binge drinking and associated mental health problems. The harms associated with alcohol consumption need to be highlighted through evidence-based prevention programs. Health and education systems need to be strengthened to screen and support young people. Focussing on policy initiatives to limit beverage companies targeting alcohol to young people will also be needed

Binge drinking : a pattern associated with a risk of problems of alcohol use among university students

Objective:: to evaluate problems associated with alcohol use among university students who reported binge drinking in comparison to students who consumed alcohol without binging. Method:: a cross-sectional study among university students (N=2,408) who accessed the website about alcohol use. Logistic and linear regression models were included in the statistical analyzes. Results:: alcohol use in the last three months was reported by 89.2% of university students; 51.6% reported binge drinking. Compared to students who did not binge drink, university students who presented this pattern were more likely to report all evaluated problems, among them: black out (aOR: 5.4); having academic problems (aOR: 3.4); acting impulsively and having regrets (aOR: 2.9); getting involved in fights (aOR: 2.6); drinking and driving (aOR: 2.6) and accepting a ride with someone who had drunk alcohol (aOR: 1.8). Students who binged also had higher scores on the Alcohol Use Disorders Identification Test (b=4.6; p<0.001), more negative consequences (b=1.0; p<0.001) and a reduced perception of the negativity of the consequences (b=-0.5; p<0.01). Conclusion:: binge drinking was associated with an increase in the chances of manifesting problems related to alcohol use. The conclusions of this study cannot be generalized for all of the Brazilian population. Objetivo:: avaliar problemas associados ao uso de álcool entre universitários que relataram binge drinking em comparação a estudantes que consumiram álcool sem binge drinking. Método:: estudo transversal entre universitários (N=2.408) que acessaram website sobre o uso de álcool. Nas análises estatísticas incluíram-se modelos de regressão logística e linear. Resultados:: o uso de álcool, nos últimos três meses, foi relatado por 89,2% dos universitários e 51,6% referiram uso binge. Comparados a estudantes que não praticaram binge, universitários que apresentaram esse padrão tiveram maior chance de relatar todos os problemas avaliados, entre eles: incapacidade de lembrar o que aconteceu (aOR:5,4); problemas acadêmicos (aOR:3,4); agir impulsivamente e se arrepender (aOR:2,9); envolver-se em brigas (aOR:2,6); dirigir após beber (aOR:2,6) e pegar carona com alguém que bebeu (aOR:1,8). Estudantes que consumiram álcool no padrão binge também apresentaram maior pontuação no Alcohol Use Disorders Identification Test (b=4,6; p<0,001), mais consequências negativas (b=1,0; p<0,001) e menos percepção da negatividade das consequências (b=-0,5; p<0,01). Conclusão:: a prática de binge drinking esteve associada ao aumento das chances de manifestação de problemas relacionados ao uso de álcool. As conclusões deste estudo não podem ser reproduzidas para toda realidade brasileira. Objetivo:: evaluar problemas asociados al uso de alcohol entre estudiantes universitarios que relataron binge drinking en comparación a estudiantes que consumieron alcohol sin binge drinking. Método:: estudio transversal entre estudiantes universitarios (N=2.408) que visitaron una página web sobre el uso de alcohol. En los análisis estadísticos, fueron incluidos modelos de regresión logística y linear. Resultados:: el uso de alcohol, en los últimos tres meses, fue relatado por 89,2% de los estudiantes universitarios, y entre ellos 51,6% relataron uso binge. En comparación a estudiantes universitarios que no practicaron binge, los estudiantes que presentaron ese estándar tuvieron una mayor oportunidad de relatar todos los problemas evaluados, entre ellos: incapacidad de recordar lo que sucedió (aOR:5,4); problemas académicos (aOR:3,4); actuar por impulso y arrepentirse (aOR:2,9); involucrarse en peleas (aOR:2,6); manejar después de beber (aOR:2,6) y compartieron viaje con alguien que bebió (aOR:1,8). Estudiantes que consumieron alcohol dentro del estándar binge también presentaron una mayor puntuación en el Alcohol Use Disorders Identification Test (b=4,6; p<0,001), más consecuencias negativas (b=1,0; p<0,001) y menor percepción de la negatividad de las consecuencias (b=-0,5; p<0,01). Conclusión:: la práctica de binge drinking estuvo asociada al aumento de las oportunidades de manifestación de problemas relacionados al alcohol. Las conclusiones de este estudio no pueden ser adaptadas a toda la realidad brasileña