Semiconductive and Photoconductive Properties of the Single Molecule Magnets Mn12_{12}-Acetate and Fe8_8Br8_8

Resistivity measurements are reported for single crystals of Mn$_{12}$-Acetate and Fe$_8$Br$_8$. Both materials exhibit a semiconductor-like, thermally activated behavior over the 200-300 K range. The activation energy, $E_a$, obtained for Mn$_{12}$-Acetate was 0.37 $\pm$ 0.05 eV, which is to be contrasted with the value of 0.55 eV deduced from the earlier reported absorption edge measurements and the range of 0.3-1 eV from intramolecular density of states calculations, assuming $2E_a$= $E_g$, the optical band gap. For Fe$_8$Br$_8$, $E_a$ was measured as 0.73 $\pm$ 0.1 eV, and is discussed in light of the available approximate band structure calculations. Some plausible pathways are indicated based on the crystal structures of both lattices. For Mn$_{12}$-Acetate, we also measured photoconductivity in the visible range; the conductivity increased by a factor of about eight on increasing the photon energy from 632.8 nm (red) to 488 nm (blue). X-ray irradiation increased the resistivity, but $E_a$ was insensitive to exposure.Comment: 7 pages, 8 figure

Challenges of comprehensive taxon sampling in comparative biology: Wrestling with rosids

Using phylogenetic approaches to test hypotheses on a large scale, in terms of both species sampling and associated species traits and occurrence data—and doing this with rigor despite all the attendant challenges—is critical for addressing many broad questions in evolution and ecology. However, application of such approaches to empirical systems is hampered by a lingering series of theoretical and practical bottlenecks. The community is still wrestling with the challenges of how to develop species‐level, comprehensively sampled phylogenies and associated geographic and phenotypic resources that enable global‐scale analyses. We illustrate difficulties and opportunities using the rosids as a case study, arguing that assembly of biodiversity data that is scale‐appropriate—and therefore comprehensive and global in scope—is required to test global‐scale hypotheses. Synthesizing comprehensive biodiversity data sets in clades such as the rosids will be key to understanding the origin and present‐day evolutionary and ecological dynamics of the angiosperms.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143800/1/ajb21059.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/143800/2/ajb21059_am.pd

Using exchange structure analysis to explore argument in text-based computer conferences

Computer conferencing provides a new site for students to develop and rehearse argumentation skills, but much remains to be learnt about how to encourage and support students in this environment. Asynchronous text-based discussion differs in significant ways from face-to-face discussion, creating a need for specially designed schemes for analysis. This paper discusses some of the problems of analysing asynchronous argumentation, and puts forward an analytical framework based on exchange structure analysis, which brings a linguistic perspective to bear on the interaction. Key features of the framework are attention to both interactive and ideational aspects of the discussion, and the ability to track the dynamic construction of argument content. The paper outlines the framework itself, and discusses some of the findings afforded by this type of analysis, and its limitations

Genetic analysis of hsCRP in American Indians: The Strong heart family study

Background Increased serum levels of C-reactive protein (CRP), an important component of the innate immune response, are associated with increased risk of cardiovascular disease (CVD). Multiple single nucleotide polymorphisms (SNP) have been identified which are associated with CRP levels, and Mendelian randomization studies have shown a positive association between SNPs increasing CRP expression and risk of colon cancer (but thus far not CVD). The effects of individual genetic variants often interact with the genetic background of a population and hence we sought to resolve the genetic determinants of serum CRP in a number of American Indian populations. Methods The Strong Heart Family Study (SHFS) has serum CRP measurements from 2428 tribal members, recruited as large families from three regions of the United States. Microsatellite markers and MetaboChip defined SNP genotypes were incorporated into variance components, decomposition-based linkage and association analyses. Results CRP levels exhibited significant heritability (h2 = 0.33 ± 0.05, p<1.3 X 10−20). A locus on chromosome (chr) 6, near marker D6S281 (approximately at 169.6 Mb, GRCh38/hg38) showed suggestive linkage (LOD = 1.9) to CRP levels. No individual SNPs were found associated with CRP levels after Bonferroni adjustment for multiple testing (threshold <7.77 x 10−7), however, we found nominal associations, many of which replicate previous findings at the CRP, HNF1A and 7 other loci. In addition, we report association of 46 SNPs located at 7 novel loci on chromosomes 2, 5, 6(2 loci), 9, 10 and 17, with an average of 15.3 Kb between SNPs and all with p-values less than 7.2 X 10−4. Conclusion In agreement with evidence from other populations, these data show CRP serum levels are under considerable genetic influence; and include loci, such as near CRP and other genes, that replicate results from other ethnic groups. These findings also suggest possible novel loci on chr 6 and other chromosomes that warrant further investigation

Physical activity and diet associations with the gut microbiota in the Coronary Artery Risk Development in Young Adults (CARDIA) study

Background: Gut microbiota may influence metabolic pathways related to chronic health conditions. Evidence for physical activity and diet influences on gut microbial composition exists, but data from diverse population-based cohort studies are limited. Objectives: We hypothesized that gut microbial diversity and genera are associated with physical activity and diet quality. Methods: Data were from 537 participants in the Coronary Artery Risk Development in Young Adults (CARDIA) Study, a prospective cohort, who attended the year 30 follow-up examination (2015–2016; aged 47–61 y; 45% Black race/55% White race; 45% men/55% women). The 16S ribosomal RNA marker gene was sequenced from stool DNA, and genus-level taxonomy was assigned. Within-person microbial diversity (α-diversity) was assessed with Shannon diversity index and richness scores; between-person diversity (β-diversity) measures were generated with principal coordinates analysis (PCoA). Current and long-term physical activity and diet quality measures were derived from data collected over 30 y of follow-up. Multivariable-adjusted regression analysis controlled for: sociodemographic variables (age, race, sex, education, and field center), other health behaviors (smoking, alcohol consumption, and medication use), and adjusted for multiple comparisons with the false discovery rate (<0.20). Results: Based on PCoA β-diversity, participants’ microbial community compositions differed significantly (P < 0.001), with respect to both current and long-term physical activity and diet quality. α-Diversity was associated only with current physical activity (positively) in multivariable-adjusted analysis. Multiple genera (n = 45) were associated with physical activity and fewer with diet (n = 5), including positive associations with Lachnospiraceae UCG-001 and Ruminococcaceae Incertae Sedis with both behaviors. Conclusions: Physical activity and diet quality were associated with gut microbial composition among 537 participants in the CARDIA study. Multiple genera were associated with physical activity. Physical activity and diet quality were associated with genera consistent with pathways related to inflammation and short-chain fatty acid production

Enhanced recovery after thoracic surgery: Systematic review and meta-analysis

The enhanced recovery after thoracic surgery (ERATS) protocol has been shown to reduce complications and hospital length of stay (LOS). In thoracic surgery, the prototypical ERATS pathway involves a preoperative phase, which focuses on patient education and smoking cessation; the intraoperative phase incorporates multimodal anesthesia along with minimally invasive surgery (video-assisted thoracoscopic surgery [VATS]); and the postoperative phase emphasizes the use of incentive spirometry, early mobilization, early chest tube and urinary catheter removal. Goal-directed fluid therapy and minimization of opioids is encouraged

Arabidopsis seed secrets unravelled after a decade of genetic and omics-driven research

Seeds play a fundamental role in colonization of the environment by spermatophytes, and seeds harvested from crops are the main food source for human beings. Knowledge of seed biology is therefore important for both fundamental and applied issues. This review on seed biology illustrates the important progress made in the field of Arabidopsis seed research over the last decade. Access to ‘omics’ tools, including the inventory of genes deduced from sequencing of the Arabidopsis genome, has speeded up the analysis of biological functions operating in seeds. This review covers the following processes: seed and seed coat development, seed reserve accumulation, seed dormancy and seed germination. We present new insights in these various fields and describe ongoing biotechnology approaches to improve seed characteristics in crops

Phenomenology of the Lense-Thirring effect in the Solar System

Recent years have seen increasing efforts to directly measure some aspects of the general relativistic gravitomagnetic interaction in several astronomical scenarios in the solar system. After briefly overviewing the concept of gravitomagnetism from a theoretical point of view, we review the performed or proposed attempts to detect the Lense-Thirring effect affecting the orbital motions of natural and artificial bodies in the gravitational fields of the Sun, Earth, Mars and Jupiter. In particular, we will focus on the evaluation of the impact of several sources of systematic uncertainties of dynamical origin to realistically elucidate the present and future perspectives in directly measuring such an elusive relativistic effect.Comment: LaTex, 51 pages, 14 figures, 22 tables. Invited review, to appear in Astrophysics and Space Science (ApSS). Some uncited references in the text now correctly quoted. One reference added. A footnote adde