10,838 research outputs found
Phenalene-phosphazene complexes: effect of exocyclic charge densities on the cyclotriphosphazene ring system
The synthesis and properties of a new series of 1,9-diamino-substituted phenalene complexes of the cyclotriphosphazene ring system is described. One of the compounds is shown to be amphoteric, and this behavior allows an examination of the response of the phosphazene linkage to variations in exocyclic charge density at the spiro center in a plane perpendicular to the cyclotriphosphazene ring system. ^(31)P NMR spectroscopy indicates that substituent lone pairs with this orientation are not effective in long-range delocalization within the phosphazene linkage (in accord with our theoretical model of spiro delocalization). An X-ray crystal structure of one compound (7) identifies the presence of clathrated molecules of chloroform together with doubly hydrogen-bonded pairs of the phenalene-phosphazene complexes in the lattice. Crystal data for 7 (C_(13)H_8Cl_4N_5P_3âąCHCl_3): monoclinic space group P2_1/c, a = 12.401 (4) Ă
, b = 28.404 (6) Ă
, c = 12.962 (3) Ă
, ÎČ = 91.76 (2)°, V = 4564 (2) Ă
^3, Z = 8, R = 0.050 for 4525 reflections
AFLOW-QHA3P: Robust and automated method to compute thermodynamic properties of solids
Accelerating the calculations of finite-temperature thermodynamic properties is a major challenge for rational materials design. Reliable methods can be quite expensive, limiting their applicability in autonomous high-throughput workflows. Here, the three-phonon quasiharmonic approximation (QHA) method is introduced, requiring only three phonon calculations to obtain a thorough characterization of the material. Leveraging a Taylor expansion of the phonon frequencies around the equilibrium volume, the method efficiently resolves the volumetric thermal expansion coefficient, specific heat at constant pressure, the enthalpy, and bulk modulus. Results from the standard QHA and experiments corroborate the procedure, and additional comparisons are made with the recently developed self-consistent QHA. The three approachesâthree-phonon, standard, and self-consistent QHAsâare all included within the open-source ab initio framework aflow, allowing the automated determination of properties with various implementations within the same framework
Southern Brazilian indigenous populations and the forest: towards an environmental history
Human societies and economies are inextricably linked to oceans and seas. Eight of the worldâs ten largest cities lie adjacent to the ocean (UN Atlas of the Oceans, 2010) and about half of the worldâs population lives within 200 km of a coast â a quarter within 100 km (IPCC, 2007). Oceans and seas provide a range of ecosystem services (including regulating, provisioning and cultural services) that enhance human wellâbeing in numerous ways (Millennium Ecosystem Assessment, 2003, 2005; Hicks, 2011). To the extent that climate change affects ecosystems, it will affect fisheries (as discussed in the preceding chapters of this book) and, by extension, human wellâbeing. In this chapter, we focus on provisioning and cultural services associated with fisheries. Although important, the oceanâs regulating and supporting services, including the fixation of atmospheric carbon, are not further discussed here (for further details, see UNEPâWCMC, 2011). We describe the numerous contributions of marineâbased ecosystems to human wellâbeing and the ways in which climate change and other confounding factors are likely to disrupt relationships between fishers, fisheries and fishing communities. Our three caseâstudies: smallâscale, artisanal and subsistenceâbased fisheries of the western Indian Ocean (WIO), fishing of cultural keystone species in the Torres Strait, and commercial fishing in Australia, serve to highlight the various changes to fisheries likely to be brought about by climate change in three markedly different contexts
Is there a Subjective Element in the Refugee Convention\u27s Requirement of \u27Well-Founded Fear\u27?
Linguistic ambiguity in the refugee definition\u27s requirement of well-founded fear of being persecuted has given rise to a wide range of interpretations. There is general agreement that a fear is well-founded only if the refugee claimant faces an actual, forward-looking risk of being persecuted in her country of origin (the objective element ). But it is less clear whether the well-founded fear standard also requires a showing that the applicant is not only genuinely at risk, but also stands in trepidation of being persecuted. Beyond vague references to the subjective quality of fear, few courts or commentators have undertaken the task of explaining what justifies recognition of a subjective element in the first place. What, in the end, does subjective fear or trepidation have to do with the goals of refugee law? Reasoned explanations are in short supply. This shortfall in critical thinking has greatly complicated efforts to formulate a coherent understanding of the subjective element, and clearly to articulate its role in the analysis of well-founded fear
Is there a Subjective Element in the Refugee Convention\u27s Requirement of \u27Well-Founded Fear\u27?
Linguistic ambiguity in the refugee definition\u27s requirement of well-founded fear of being persecuted has given rise to a wide range of interpretations. There is general agreement that a fear is well-founded only if the refugee claimant faces an actual, forward-looking risk of being persecuted in her country of origin (the objective element ). But it is less clear whether the well-founded fear standard also requires a showing that the applicant is not only genuinely at risk, but also stands in trepidation of being persecuted. Beyond vague references to the subjective quality of fear, few courts or commentators have undertaken the task of explaining what justifies recognition of a subjective element in the first place. What, in the end, does subjective fear or trepidation have to do with the goals of refugee law? Reasoned explanations are in short supply. This shortfall in critical thinking has greatly complicated efforts to formulate a coherent understanding of the subjective element, and clearly to articulate its role in the analysis of well-founded fear
The Keck/OSIRIS Nearby AGN Survey (KONA) I. The Nuclear K-band Properties of Nearby AGN
We introduce the Keck Osiris Nearby AGN survey (KONA), a new adaptive
optics-assisted integral-field spectroscopic survey of Seyfert galaxies. KONA
permits at ~0.1" resolution a detailed study of the nuclear kinematic structure
of gas and stars in a representative sample of 40 local bona fide active
galactic nucleus (AGN). KONA seeks to characterize the physical processes
responsible for the coevolution of supermassive black holes and galaxies,
principally inflows and outflows. With these IFU data of the nuclear regions of
40 Seyfert galaxies, the KONA survey will be able to study, for the first time,
a number of key topics with meaningful statistics. In this paper we study the
nuclear K-band properties of nearby AGN. We find that the luminosities of the
unresolved Seyfert 1 sources at 2.1 microns are correlated with the hard X-ray
luminosities, implying that the majority of the emission is non-stellar. The
best-fit correlation is logLK = 0.9logL2-10 keV + 4 over 3 orders of magnitude
in both K-band and X-ray luminosities. We find no strong correlation between
2.1 microns luminosity and hard X-ray luminosity for the Seyfert 2 galaxies.
The spatial extent and spectral slope of the Seyfert 2 galaxies indicate the
presence of nuclear star formation and attenuating material (gas and dust),
which in some cases is compact and in some galaxies extended. We detect
coronal-line emission in 36 galaxies and for the first time in five galaxies.
Finally, we find 4/20 galaxies that are optically classified as Seyfert 2 show
broad emission lines in the near-IR, and one galaxy (NGC 7465) shows evidence
of a double nucleus.Comment: Accepted for publication in ApJ, 19 pages with 18 figure
Optimizing sustainable multimodal distribution networks in the context of carbonpricing, with a case study in the Thai sugar industry
Transportation is a major cause of energy consumption and emissions which can bereduced by optimizing routings and using alternative modes of transport. This paperrelates to the strategic design of multimodal transportation networks. It presents ageneral model of green vehicle routing problems that supports strategic decisionmakingby identifying optimal solutions and provides data on costs and emissions.Three general linear programming models were developed that optimize multimodaldistribution networks that could be applied in many industries. Model I evaluatescarbon emissions; model II assesses carbon emissions and capacity constraints; andmodel III establishes total costs including transportation, handling, storage, fuel andcarbon costs.Thailand is the third largest world sugar exporter in the world and is piloting carbonpricing, which will affect energy intensive industries, including the sugar industry. Themodels are applied using data obtained from a collaborating company. The researchcontributed to practice by informing managerial decisions relating to the export of sugarfrom the factory. This included evaluating the possible use of a dry port with railconnections, which could reduce transportation and carbon costs by 54.3% andfacilitate the building of another factory to increase exports
Star Formation in Emission-Line Galaxies Between Redshifts of 0.8 and 1.6
Optical spectra of 14 emission-line galaxies representative of the 1999
NICMOS parallel grism Ha survey of McCarthy et al. are presented. Of the 14, 9
have emission lines confirming the redshifts found in the grism survey. The
higher resolution of our optical spectra improves the redshift accuracy by a
factor of 5. The [O II]/Ha values of our sample are found to be more than two
times lower than expected from Jansen et al. This [O II]/Ha ratio discrepancy
is most likely explained by additional reddening in our Ha-selected sample [on
average, as much as an extra E(B-V) = 0.6], as well as to a possible stronger
dependence of the [O II]/Ha ratio on galaxy luminosity than is found in local
galaxies. The result is that star formation rates (SFRs) calculated from [O
II]3727 emission, uncorrected for extinction, are found to be on average 4 +/-
2 times lower than the SFRs calculated from Ha emission. Classification of
emission-line galaxies as starburst or Seyfert galaxies based on comparison of
the ratios [O II]/Hb and [Ne III]3869/Hb is discussed. New Seyfert 1
diagnostics using the Ha line luminosity, H-band absolute magnitude, and Ha
equivalent widths are also presented. One galaxy is classified as a Seyfert 1
based on its broad emission lines, implying a comoving number density for
Seyfert 1s of 2.5{+5.9, -2.1} times 10^{-5} Mpc^{-3}. This commoving number
density is a factor of 2.4{+5.5,-2.0} times higher than estimated by other
surveys.Comment: 51 pages, 18 figures; Accepted for publication in the Astrophysical
Journal; Revised version with minor changes and an additional reference which
gives further support to our conclusion
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Antegrade common femoral artery closure device use is associated with decreased complications.
ObjectiveAntegrade femoral artery access is often used for ipsilateral infrainguinal peripheral vascular intervention. However, the use of closure devices (CD) for antegrade access (AA) is still considered outside the instructions for use for most devices. We hypothesized that CD use for antegrade femoral access would not be associated with an increased odds of access site complications.MethodsThe Vascular Quality Initiative was queried from 2010 to 2019 for infrainguinal peripheral vascular interventions performed via femoral AA. Patients who had a cutdown or multiple access sites were excluded. Cases were then stratified into whether a CD was used or not. Hierarchical multivariable logistic regressions controlling for hospital-level variation were used to examine the independent association between CD use and access site complications. A sensitivity analysis using coarsened exact matching was performed using factors different between treatment groups to reduce imbalance between the groups.ResultsOverall, 11,562 cases were identified and 5693 (49.2%) used a CD. Patients treated with a CD were less likely to be white (74.1% vs 75.2%), have coronary artery disease (29.7% vs 33.4%), use aspirin (68.7% vs 72.4%), and have heparin reversal with protamine (15.5% vs 25.6%; all P < .05). CD patients were more likely to be obese (31.6% vs 27.0%), have an elective operation (82.6% vs 80.1%), ultrasound-guided access (75.5% vs 60.6%), and a larger access sheath (6.0 ± 1.0 F vs 5.5 ± 1.0 F; P < .05 for all). CD cases were less likely to develop any access site hematoma (2.55% vs 3.53%; P < .01) or a hematoma requiring reintervention (0.63% vs 1.26%; P < .01) and had no difference in access site stenosis or occlusion (0.30% vs 0.22%; P = .47) compared with no CD. On multivariable analysis, CD cases had significantly decreased odds of developing any access site hematoma (odds ratio, 0.75; 95% confidence interval, 0.59-0.95) and a hematoma requiring intervention (odds ratio, 0.56; 95% confidence interval, 0.38-0.81). A sensitivity analysis after coarsened exact matching confirmed these findings.ConclusionsIn this nationally representative sample, CD use for AA was associated with a lower odds of hematoma in selected patients. Extending the instructions for use indications for CDs to include femoral AA may decrease the incidence of access site complications, patient exposure to reintervention, and costs to the health care system
Multiwavelength Mass Comparisons of the z~0.3 CNOC Cluster Sample
Results are presented from a detailed analysis of optical and X-ray
observations of moderate-redshift galaxy clusters from the Canadian Network for
Observational Cosmology (CNOC) subsample of the EMSS. The combination of
extensive optical and deep X-ray observations of these clusters make them ideal
candidates for multiwavelength mass comparison studies. X-ray surface
brightness profiles of 14 clusters with 0.17<z<0.55 are constructed from
Chandra observations and fit to single and double beta-models. Spatially
resolved temperature analysis is performed, indicating that five of the
clusters in this sample exhibit temperature gradients within their inner 60-200
kpc. Integrated spectra extracted within R_2500 provide temperature, abundance,
and luminosity information. Under assumptions of hydrostatic equilibrium and
spherical symmetry, we derive gas and total masses within R_2500 and R_200. We
find an average gas mass fraction within R_200 of 0.136 +/- 0.004, resulting in
Omega_m=0.28 +/- 0.01 (formal error). We also derive dynamical masses for these
clusters to R_200. We find no systematic bias between X-ray and dynamical
methods across the sample, with an average M(dyn)/M(X-ray) = 0.97 +/- 0.05. We
also compare X-ray masses to weak lensing mass estimates of a subset of our
sample, resulting in a weighted average of M(lens)/M(X-ray) of 0.99 +/- 0.07.
We investigate X-ray scaling relationships and find powerlaw slopes which are
slightly steeper than the predictions of self-similar models, with an E(z)^(-1)
Lx-Tx slope of 2.4 +/- 0.2 and an E(z) M_2500-Tx slope of 1.7 +/- 0.1.
Relationships between red-sequence optical richness (B_gc,red) and global
cluster X-ray properties (Tx, Lx and M_2500) are also examined and fitted.Comment: Astrophysical Journal, 48 pages, 11 figures, LaTeX. Added correction
to surface brightness normalization of MS1512.4+3647, corrections to sample
gas mass fractions and calculated value of Omega_m. Figure resolution has
been reduced to comply with astro-ph upload requirement
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