The effect of extra dimensions on gravity wave bursts from cosmic string cusps

We explore the kinematical effect of having extra dimensions on the gravity wave emission from cosmic strings. Additional dimensions both round off cusps, and reduce the probability of their formation. We recompute the gravity wave burst, taking into account these two factors, and find a potentially significant damping on the gravity waves of the strings.Comment: 33 pages, 8 figures, published versio

Gravitational Wave Bursts from Cosmic Superstring Reconnections

We compute the gravitational waveform produced by cosmic superstring reconnections. This is done by first constructing the superstring reconnection trajectory, which closely resembles that of classical, instantaneous reconnection but with the singularities smoothed out due to the string path integral. We then evaluate the graviton vertex operator in this background to obtain the burst amplitude. The result is compared to the detection threshold for current and future gravitational wave detectors, finding that neither bursts nor the stochastic background would be detectable by Advanced LIGO. This disappointing but anticipated conclusion holds even for the most optimistic values of the reconnection probability and loop sizes.Comment: 26 pages, 6 figures; v2: references added and typos correcte

The epidemiology of adolescents living with perinatally acquired HIV: A cross-region global cohort analysis

Background: Globally, the population of adolescents living with perinatally acquired HIV (APHs) continues to expand. In this study, we pooled data from observational pediatric HIV cohorts and cohort networks, allowing comparisons of adolescents with perinatally acquired HIV in "real-life" settings across multiple regions. We describe the geographic and temporal characteristics and mortality outcomes of APHs across multiple regions, including South America and the Caribbean, North America, Europe, sub-Saharan Africa, and South and Southeast Asia. Methods and findings: Through the Collaborative Initiative for Paediatric HIV Education and Research (CIPHER), individual retrospective longitudinal data from 12 cohort networks were pooled. All children infected with HIV who entered care before age 10 years, were not known to have horizontally acquired HIV, and were followed up beyond age 10 years were included in this analysis conducted from May 2016 to January 2017. Our primary analysis describes patient and treatment characteristics of APHs at key time points, including first HIV-associated clinic visit, antiretroviral therapy (ART) start, age 10 years, and last visit, and compares these characteristics by geographic region, country income group (CIG), and birth period. Our secondary analysis describes mortality, transfer out, and lost to follow-up (LTFU) as outcomes at age 15 years, using competing risk analysis. Among the 38,187 APHs included, 51% were female, 79% were from sub-Saharan Africa and 65% lived in low-income countries. APHs from 51 countries were included (Europe: 14 countries and 3,054 APHs; North America: 1 country and 1,032 APHs; South America and the Caribbean: 4 countries and 903 APHs; South and Southeast Asia: 7 countries and 2,902 APHs; sub-Saharan Africa, 25 countries and 30,296 APHs). Observation started as early as 1982 in Europe and 1996 in sub-Saharan Africa, and continued until at least 2014 in all regions. The median (interquartile range [IQR]) duration of adolescent follow-up was 3.1 (1.5-5.2) years for the total cohort and 6.4 (3.6-8.0) years in Europe, 3.7 (2.0-5.4) years in North America, 2.5 (1.2-4.4) years in South and Southeast Asia, 5.0 (2.7-7.5) years in South America and the Caribbean, and 2.1 (0.9-3.8) years in sub-Saharan Africa. Median (IQR) age at first visit differed substantially by region, ranging from 0.7 (0.3-2.1) years in North America to 7.1 (5.3-8.6) years in sub-Saharan Africa. The median age at ART start varied from 0.9 (0.4-2.6) years in North America to 7.9 (6.0-9.3) years in sub-Saharan Africa. The cumulative incidence estimates (95% confidence interval [CI]) at age 15 years for mortality, transfers out, and LTFU for all APHs were 2.6% (2.4%-2.8%), 15.6% (15.1%-16.0%), and 11.3% (10.9%-11.8%), respectively. Mortality was lowest in Europe (0.8% [0.5%-1.1%]) and highest in South America and the Caribbean (4.4% [3.1%-6.1%]). However, LTFU was lowest in South America and the Caribbean (4.8% [3.4%-6.7%]) and highest in sub-Saharan Africa (13.2% [12.6%-13.7%]). Study limitations include the high LTFU rate in sub-Saharan Africa, which could have affected the comparison of mortality across regions; inclusion of data only for APHs receiving ART from some countries; and unavailability of data from high-burden countries such as Nigeria. Conclusion: To our knowledge, our study represents the largest multiregional epidemiological analysis of APHs. Despite probable under-ascertained mortality, mortality in APHs remains substantially higher in sub-Saharan Africa, South and Southeast Asia, and South America and the Caribbean than in Europe. Collaborations such as CIPHER enable us to monitor current global temporal trends in outcomes over time to inform appropriate policy responses.info:eu-repo/semantics/publishedVersio

β-Methylamino-L-alanine (BMAA)

The nonproteinogenic amino acid, β-methylamino-L-alanine (BMAA;Figure 2.7), has been postulated to be a cause of neurodegenerative diseasesthat affect large numbers of people. However, at the time of publication of thisdocument, this hypothesis is still highly controversial and a number of inconsistencies must be clarified before its role in human disease can be assessedwith more certainty. The following section introduces and discusses these.Interest in BMAA began as a result of a neurological disease known asamyotrophic lateral sclerosis/Parkinsonism dementia complex (ALS/PDC)present in the island of Guam in the Pacific (Arnold et al., 1953; Kurlandet al., 1961). ALS/PDC has also been identified in small populations in IrianJaya (western New Guinea) and Kii Peninsula of Japan. ALS/PDC has a spectrum of symptoms that resemble ALS, Parkinsonism and dementia. Differenttypes of neurological dysfunctions were commonly present in the same individual, and multiple cases were often seen within families. The disease rendered patients incapable of normal movement, produced memory decline,cognitive deficits, and often led to premature death. In Guam, the peak incidence of the disease occurred during the 1950s and has been declining sincethen (Plato et al., 2002; Plato et al., 2003). The disease seemed limited tothe indigenous population or others who had lived in Guam and adoptedlocal customs and diet. ALS/PDC is characterised by hyperphosphorylatedtau proteins that may assemble into masses ranging from a few moleculesto large amyloid masses that may propagate like prions (Buée et al., 2000;Jucker & Walker, 2013). The altered proteins form neurofibrillary tangles(NFTs), disrupting cell structure associated with loss of function and/or celldeath (Walker & LeVine, 2000; Chiti & Dobson, 2006)

Approximating the Online Set Multicover Problems Via Randomized Winnowing

In this paper, we consider the weighted online set k-multicover problem. In this problem, we have an universe V of elements, a family S of subsets of V with a positive real cost for every S ∈S, and a “coverage factor” (positive integer) k. A subset {i0,i1,...} ⊆ V of elements are presented online in an arbitrary order. When each element ip is presented, we are also told the collection of all (at least k) sets Sip ⊆ S and their costs in which ip belongs and we need to select additional sets from Sip if necessary such that our collection of selected sets contains at least k sets that contain the element ip. The goal is to minimize the total cost of the selected sets 3. In this paper, we describe a new randomized algorithm for the online multicover problem based on the randomized winnowing approach of [11]. This algorithm generalizes and improves some earlier results in [1]. We also discuss lower bounds on competitive ratios for deterministic algorithms for general k based on the approaches in [1]