Energy spectrum of turbulent fluctuations in boundary driven reduced magnetohydrodynamics

The nonlinear dynamics of a bundle of magnetic flux ropes driven by stationary fluid motions at their endpoints is studied, by performing numerical simulations of the magnetohydrodynamic (MHD) equations. The development of MHD turbulence is shown, where the system reaches a state that is characterized by the ratio between the Alfven time (the time for incompressible MHD waves to travel along the field lines) and the convective time scale of the driving motions. This ratio of time scales determines the energy spectra and the relaxation toward different regimes ranging from weak to strong turbulence. A connection is made with phenomenological theories for the energy spectra in MHD turbulence.Comment: Published in Physics of Plasma

Ethics and Childhood Vaccination Policy in the United States

Childhood immunization involves a balance between parents' autonomy in deciding whether to immunize their children and the benefits to public health from mandating vaccines. Ethical concerns about pediatric vaccination span several public health domains, including those of policymakers, clinicians, and other professionals. In light of ongoing developments and debates, we discuss several key ethical issues concerning childhood immunization in the United States and describe how they affect policy development and clinical practice. We focus on ethical considerations pertaining to herd immunity as a community good, vaccine communication, dismissal of vaccine-refusing families from practice, and vaccine mandates. Clinicians and policymakers need to consider the nature and timing of vaccine-related discussions and invoke deliberative approaches to policy-making

The influence of resuscitation preferences on obstetrical management of periviable deliveries

Objective Determine the relative influence of patient's resuscitation preferences on periviable delivery management. Methods Surveyed 295 obstetrician-gynecologists about managing periviable preterm premature rupture of membranes. Across 10 vignettes, we systematically varied gestational age; occupation; method of conception; and resuscitation preference. Physicians rated their likelihood (0-10) of proceeding with induction, steroids, and cesarean. Data were analyzed via conjoint analysis. Results 205 physician responses were included. Median ratings for management decisions were: induction 1.89; steroids 5.00; cesarean for labor 3.89; cesarean for distress 4.11. Gestational age had the greatest influence on physician ratings across all decisions (importance values ranging from 72.6-86.6), followed by patient's resuscitation preference (range= 9.3-21.4). Conclusion Gestational age is weighted more heavily than patients’ resuscitation preferences in obstetricians’ decision-making for periviable delivery management. Misalignment of antenatal management with parental resuscitation preferences may adversely affect periviable outcomes. Interventions are needed to facilitate more patient-centered decision-making in periviable care

Interacting effects of temperature, habitat and phenotype on predator avoidance behaviour in <i>Diadema antillarum</i>: implications for restorative conservation

Caribbean long-spined sea urchin Diadema antillarum populations crashed following a mass mortality event in 1983-1984 with cascading effects on reef health. Population restoration efforts may be hampered by unknown effects of short- and long-term elevated sea surface temperature (SST). We investigated how a key behavioural trait, predator avoidance behaviour (PAB; percentage of long defensive spines that moved in response to shadow stimuli), was affected by elevated SST in 180 individuals from 2 contrasting Honduran reefs: Utila (flattened reef structure, dearth of predation refugia) and Banco Capiro (complex reef structure, abundant refugia). Initiation of PAB is mediated by melanin, which breaks down at elevated water temperatures; thus, as SST rises, D. antillarum may become vulnerable to predation. We compared local current SST (CSST; 29.7°C) with 2 IPCC predicted long-term climate change scenarios under laboratory conditions. PAB decreased by 13.98-15.37% at CSST +1.4°C and 31.67-42.44% at CSST +3.1°C. Trial temperatures were similar to maxima recorded in the Caribbean during the 2016 El Niño, so our results also represent likely responses to worst-case short-term acute temperature anomalies. Juveniles maintained higher PAB than adults, indicating increased reliance on anti-predation behaviours. White-spined phenotypes from Utila’s flattened reef maintained higher PAB than black-spined counterparts, likely due to increased conspicuousness to visual predators. Habitat complexity may mitigate temperature-driven losses in natural behavioural defences. D. antillarum may be resilient to near-term (D. antillarum populations must be coupled to augmented reef complexity to improve future resilience

Vaccine message framing and parents' intent to immunize their infants for MMR

BACKGROUND AND OBJECTIVE: Emphasizing societal benefits of vaccines has been linked to increased vaccination intentions in adults. It is unclear if this pattern holds for parents deciding whether to vaccinate their children. The objective was to determine whether emphasizing the benefits of measles-mumps-rubella (MMR) vaccination directly to the vaccine recipient or to society differentially impacts parents' vaccine intentions for their infants. METHODS: In a national online survey, parents (N = 802) of infants <12 months old were randomly assigned to receive 1 of 4 MMR vaccine messages: (1) the Centers for Disease Control and Prevention Vaccine Information Statement (VIS), (2) VIS and information emphasizing the MMR vaccine's benefits to the child, (3) VIS and information emphasizing societal benefits, or (4) VIS and information emphasizing benefits both to the child and society. Parents reported their likelihood of vaccinating their infants for MMR on a response scale of 0 (extremely unlikely) to 100 (extremely likely). RESULTS: Compared with the VIS-only group (mean intention = 86.3), parents reported increased vaccine intentions for their infants when receiving additional information emphasizing the MMR vaccine's benefits either directly to the child (mean intention = 91.6, P = .01) or to both the child and society (mean intention = 90.8, P = .03). Emphasizing the MMR vaccine's benefits only to society did not increase intentions (mean intention = 86.4, P = .97). CONCLUSIONS: We did not see increases in parents' MMR vaccine intentions for their infants when societal benefits were emphasized without mention of benefits directly to the child. This finding suggests that providers should emphasize benefits directly to the child. Mentioning societal benefits seems to neither add value to, nor interfere with, information highlighting benefits directly to the child

Genome landscapes and bacteriophage codon usage

Across all kingdoms of biological life, protein-coding genes exhibit unequal usage of synonmous codons. Although alternative theories abound, translational selection has been accepted as an important mechanism that shapes the patterns of codon usage in prokaryotes and simple eukaryotes. Here we analyze patterns of codon usage across 74 diverse bacteriophages that infect E. coli, P. aeruginosa and L. lactis as their primary host. We introduce the concept of a `genome landscape,' which helps reveal non-trivial, long-range patterns in codon usage across a genome. We develop a series of randomization tests that allow us to interrogate the significance of one aspect of codon usage, such a GC content, while controlling for another aspect, such as adaptation to host-preferred codons. We find that 33 phage genomes exhibit highly non-random patterns in their GC3-content, use of host-preferred codons, or both. We show that the head and tail proteins of these phages exhibit significant bias towards host-preferred codons, relative to the non-structural phage proteins. Our results support the hypothesis of translational selection on viral genes for host-preferred codons, over a broad range of bacteriophages.Comment: 9 Color Figures, 5 Tables, 53 Reference

Cluster J Mycobacteriophages: Intron Splicing in Capsid and Tail Genes

Bacteriophages isolated on Mycobacterium smegmatis mc2155 represent many distinct genomes sharing little or no DNA sequence similarity. The genomes are architecturally mosaic and are replete with genes of unknown function. A new group of genomes sharing substantial nucleotide sequences constitute Cluster J. The six mycobacteriophages forming Cluster J are morphologically members of the Siphoviridae, but have unusually long genomes ranging from 106.3 to 117 kbp. Reconstruction of the capsid by cryo-electron microscopy of mycobacteriophage BAKA reveals an icosahedral structure with a triangulation number of 13. All six phages are temperate and homoimmune, and prophage establishment involves integration into a tRNA-Leu gene not previously identified as a mycobacterial attB site for phage integration. The Cluster J genomes provide two examples of intron splicing within the virion structural genes, one in a major capsid subunit gene, and one in a tail gene. These genomes also contain numerous free-standing HNH homing endonuclease, and comparative analysis reveals how these could contribute to genome mosaicism. The unusual Cluster J genomes provide new insights into phage genome architecture, gene function, capsid structure, gene mobility, intron splicing, and evolution. © 2013 Pope et al

Equilibrium Sampling From Nonequilibrium Dynamics

We present some applications of an Interacting Particle System (IPS) methodology to the field of Molecular Dynamics. This IPS method allows several simulations of a switched random process to keep closer to equilibrium at each time, thanks to a selection mechanism based on the relative virtual work induced on the system. It is therefore an efficient improvement of usual non-equilibrium simulations, which can be used to compute canonical averages, free energy differences, and typical transitions paths

Measuring cognition and function in the preclinical stage of Alzheimer\u27s disease

© 2018 The Authors The Alzheimer\u27s Association\u27s Research Roundtable met in November 2016 to explore how best to measure changes in cognition and function in the preclinical stage of Alzheimer\u27s disease. This review will cover the tools and instruments currently available to identify populations for prevention trials, and measure subtle disease progression in the earliest stages of Alzheimer\u27s disease, and will include discussions of suitable cognitive, behavioral, functional, composite, and biological endpoints for prevention trials. Current prevention trials are reviewed including TOMMOROW, Alzheimer\u27s Prevention Initiative Autosomal Dominant Alzheimer\u27s Disease Trial, the Alzheimer\u27s Prevention Initiative Generation Study, and the Anti-Amyloid Treatment in Asymptomatic Alzheimer\u27s to compare current approaches and tools that are being developed