Spectral Measures of Bipartivity in Complex Networks

We introduce a quantitative measure of network bipartivity as a proportion of even to total number of closed walks in the network. Spectral graph theory is used to quantify how close to bipartite a network is and the extent to which individual nodes and edges contribute to the global network bipartivity. It is shown that the bipartivity characterizes the network structure and can be related to the efficiency of semantic or communication networks, trophic interactions in food webs, construction principles in metabolic networks, or communities in social networks.Comment: 16 pages, 1 figure, 1 tabl

Medical, Recreational, and Mixed Marijuana Users: An Examination of Physical and Mental Health Correlates

Marijuana use in the U.S. doubled between 2001 and 2013, largely due to increases in legalization laws. Little attention, however, is given to the type of marijuana user (e.g., recreational or medical), particularly with health outcomes. Our study used data from the 2017 Behavioral Risk Factor Surveillance System (N=5,349) to examine physical health, mental health, and demographic variables by marijuana user type (including non-marijuana users). In physical health, the non-marijuana group was generally healthier, getting the most sleep, lowest BMI, and lowest alcoholic consumption. Medical users self-reported the poorest physical health, BMI, and sleep. Similar results were found in the mental health category between non-marijuana and medical users. Future longitudinal research is needed to investigate whether medical users, over time, increase their marijuana use to include recreational use (i.e., become mixed users) as a method of coping with the combination of health, emotional, and quality of life problems. Although this is among the first nationally representative studies to examine unique marijuana user groups, future studies should track user groups over time to understand the implications of transitioning into medical or recreational user groups

Post-aragonite phases of CaCO3_{3} at lower mantle pressures

The stability, structure and properties of carbonate minerals at lower mantle conditions has significant impact on our understanding of the global carbon cycle and the composition of the interior of the Earth. In recent years, there has been significant interest in the behavior of carbonates at lower mantle conditions, specifically in their carbon hybridization, which has relevance for the storage of carbon within the deep mantle. Using high-pressure synchrotron X-ray diffraction in a diamond anvil cell coupled with direct laser heating of CaCO$_{3}$ using a CO$_{2}$ laser, we identify a crystalline phase of the material above 40 GPa $-$ corresponding to a lower mantle depth of around 1,000 km $-$ which has first been predicted by \textit{ab initio} structure predictions. The observed $sp^{2}$ carbon hybridized species at 40 GPa is monoclinic with $P2_{1}/c$ symmetry and is stable up to 50 GPa, above which it transforms into a structure which cannot be indexed by existing known phases. A combination of \textit{ab initio} random structure search (AIRSS) and quasi-harmonic approximation (QHA) calculations are used to re-explore the relative phase stabilities of the rich phase diagram of CaCO$_{3}$. Nudged elastic band (NEB) calculations are used to investigate the reaction mechanisms between relevant crystal phases of CaCO$_{3}$ and we postulate that the mineral is capable of undergoing $sp^{2}$-$sp^{3}$ hybridization change purely in the $P2_{1}/c$ structure $-$ forgoing the accepted post-aragonite $Pmmn$ structure.Comment: 12 pages, 8 figure

The Uneven Influence of Climate Trends and Agricultural Policies on Maize Production in the Yucatan Peninsula, Mexico

Maize is an important staple crop in Mexico, and the recent intensification of climate variability, in combination with non-climatic forces, has hindered increases in production, especially for smallholder farmers. This article demonstrates the influence of these drivers on maize production trends in the three states of the Yucatan Peninsula using a mixed methods approach of climatic analysis and semi-structured interviews. Climate trend analysis and generalized additive models (GAMs) demonstrate relationships between production and climatic variability, using 1980–2010 precipitation and temperature data. Data from forty interviews with government officials and representatives of farmers\u27 associations (gathered in 2015 and 2016) highlight the influence of agricultural policy on maize production in the region. The climate trend analysis yielded mixed results, with a statistically significant negative rainfall trend for Quintana Roo and variability in maximum temperature changes across the region, with an increase in Yucatan State and Quintana Roo and a decrease in Campeche. Climate and production GAMs indicate a strong significant relationship between production and climate fluctuations for Campeche (79%) and Quintana Roo (72%) and a weaker significant relationship for the Yucatan State (31%). Informants identified precipitation variability and ineffective public policies for smallholder agricultural development as primary obstacles for maize production, including inadequate design of agricultural programs, inconsistent agricultural support, and ineffective farmers\u27 organizations. Quantifying the influence of climate change on maize production, and the amplifying influence of national and regional agricultural policy for smallholder farmers, will inform more appropriate policy design and implementation

Mechanistic influence of sub-micrometer porosity on the hydrogen environment-assisted cracking behavior of additively manufactured 17-4PH steel

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Systematic comparison of bacterial feeding strains for increased yield of Caenorhabditis elegans males by RNA interference-induced non-disjunction

AbstractRare Caenorhabditis elegans males arise when sex chromosome non-disjunction occurs during meiosis in self-fertilizing hermaphrodites. Non-disjunction is a relatively rare event, and males are typically observed at a frequency of less than one in five hundred wild-type animals. Males are required for genetic crosses and phenotypic analysis, yet current methods to generate large numbers of males can be cumbersome. Here, we identify RNAi reagents (dsRNA-expressing bacteria) with improved effectiveness for eliciting males. Specifically, we used RNAi to systematically reduce the expression of over two hundred genes with meiotic chromosome segregation functions, and we identified a set of RNAi reagents that robustly and reproducibly elicited male progeny

Safety and Pharmacokinetics of a Four Monoclonal Antibody Combination Against Botulinum C and D Neurotoxins.

Botulism is caused by botulinum neurotoxin (BoNT), the most poisonous substance known. BoNTs are also classified as Tier 1 biothreat agents due to their high potency and lethality. The existence of seven BoNT serotypes (A-G), which differ between 35% to 68% in amino acid sequence, necessitates the development of serotype specific countermeasures. We present results of a Phase 1 clinical study of an anti-toxin to BoNT serotypes C and D, NTM-1634, which consists of an equimolar mixture of four fully human IgG1 monoclonal antibodies (mAbs), each binding to non-overlapping epitopes on BoNT serotypes C and D resulting in potent toxin neutralization in rodents. This first-in-human study evaluated the safety and pharmacokinetics of escalating doses of NTM-1634 administered intravenously to healthy adults (NCT03046550). Three cohorts of eight healthy subjects received a single intravenous dose of NTM-1634 or placebo at 0.33 mg/kg, 0.66 mg/kg or 1 mg/kg. Follow-up examinations and pharmacokinetic evaluations were continued up to 121 days post-infusion. Subjects were monitored using physical examinations, hematology and chemistry blood tests, and electrocardiograms. Pharmacokinetic parameters were estimated using noncompartmental methods. The results demonstrated that the materials were safe and well-tolerated with the expected half-lives for human mAbs and with minimal anti-drug antibodies detected over the dose ranges and duration of the study