We investigate the conditions of ideal magnetohydrodynamic (MHD) turbulence responsible for the relative orientation between density gradients (∇ρ) and magnetic fields (B) in molecular clouds (MCs). ...For that purpose, we construct an expression for the time evolution of the angle (φ) between ∇ρ and B based on the transport equations of MHD turbulence. Using this expression, we find that the configuration where ∇ρ and B are mostly parallel, cosφ = ± 1, and where ∇ρ and B are mostly perpendicular, cosφ = 0, constitute equilibrium points, that is, the system tends to evolve towards either of these configurations and they are more represented than others. This would explain the predominant alignment or anti-alignment between column density (NH) structures and the projected magnetic field orientation (⟨B̂⊥⟩) reported in observations. Additionally, we find that departures from the cosφ = 0 configurations are related to convergent flows, quantified by the divergence of the velocity field (∇·v) in the presence of a relatively strong magnetic field. This would explain the observed change in relative orientation between NH structures and ⟨B̂⊥⟩ towards MCs, from mostly parallel at low NH to mostly perpendicular at the highest NH, as the result of the gravitational collapse and/or convergence of flows. Finally, we show that the density threshold that marks the observed change in relative orientation towards MCs, from NH and ⟨B̂⊥⟩ being mostly parallel at low NH to mostly perpendicular at the highest NH, is related to the magnetic field strength and constitutes a crucial piece of information for determining the role of the magnetic field in the dynamics of MCs.
We describe a morphological imprint of magnetization found when considering the relative orientation of the magnetic field direction with respect to the density structures in simulated turbulent ...molecular clouds. This imprint was found using the Histogram of Relative Orientations (HRO), a new technique that utilizes the gradient to characterize the directionality of density and column density structures on multiple scales. We present results of the HRO analysis in three models of molecular clouds in which the initial magnetic field strength is varied, but an identical initial turbulent velocity field is introduced, which subsequently decays. The HRO analysis was applied to the simulated data cubes and mock-observations of the simulations produced by integrating the data cube along particular lines of sight. In the three-dimensional analysis we describe the relative orientation of the magnetic field B with respect to the density structures, showing that: (1) the magnetic field shows a preferential orientation parallel to most of the density structures in the three simulated cubes, (2) the relative orientation changes from parallel to perpendicular in regions with density over a critical density nT in the highest magnetization case, and (3) the change of relative orientation is largest for the highest magnetization and decreases in lower magnetization cases. This change in the relative orientation is also present in the projected maps. In conjunction with simulations, HROs can be used to establish a link between the observed morphology in polarization maps and the physics included in simulations of molecular clouds.
A short, easy-to-use health status questionnaire is needed in the multidimensional assessment of chronic obstructive pulmonary disease (COPD) in routine practice. The performance of the eight-item ...COPD assessment test (CAT) was analysed in 1,817 patients from primary care in seven European countries. The CAT has a scoring range of 0-40 (high score representing poor health status). Mean CAT scores indicated significant health status impairment that was related to severity of airway obstruction, but within each Global Initiative for Obstructive Lung Disease stage (I to IV) there was a wide range of scores (I: 16.2 ± 8.8; II: 16.3 ± 7.9; III: 19.3 ± 8.2; and IV: 22.3 ± 8.7; I versus II, p = 0.88; II versus III, p<0.0001; III versus IV, p = 0.0001). CAT scores showed relatively little variability across countries (within ± 12% of the mean across all countries). Scores were significantly better in patients who were stable (17.2 ± 8.3) versus those suffering an exacerbation (21.3 ± 8.4) (p<0.0001); and in patients with no (17.3 ± 8.1) or one or two (16.6 ± 8.2) versus three or more (19.7 ± 8.5) comorbidities (p<0.0001 for both). The CAT distinguished between classes of other impairment measures and was strongly correlated with the St George's Respiratory Questionnaire (r = 0.8, p<0.0001). The CAT is a simple and easy-to-use questionnaire that distinguishes between patients of different degrees of COPD severity and appears to behave the same way across countries.
Background: Patients with chronic obstructive pulmonary disease (COPD) often present with severe acute exacerbations requiring hospital treatment. However, little is known about the prognostic ...consequences of these exacerbations. A study was undertaken to investigate whether severe acute exacerbations of COPD exert a direct effect on mortality. Methods: Multivariate techniques were used to analyse the prognostic influence of acute exacerbations of COPD treated in hospital (visits to the emergency service and admissions), patient age, smoking, body mass index, co-morbidity, long term oxygen therapy, forced spirometric parameters, and arterial blood gas tensions in a prospective cohort of 304 men with COPD followed up for 5 years. The mean (SD) age of the patients was 71 (9) years and forced expiratory volume in 1 second was 46 (17)%. Results: Only older age (hazard ratio (HR) 5.28, 95% CI 1.75 to 15.93), arterial carbon dioxide tension (HR 1.07, 95% CI 1.02 to 1.12), and acute exacerbations of COPD were found to be independent indicators of a poor prognosis. The patients with the greatest mortality risk were those with three or more acute COPD exacerbations (HR 4.13, 95% CI 1.80 to 9.41). Conclusions: This study shows for the first time that severe acute exacerbations of COPD have an independent negative impact on patient prognosis. Mortality increases with the frequency of severe exacerbations, particularly if these require admission to hospital.
•SEW preservation drives the financial decision-making process in family SMEs.•SEW preservation in family SMEs negatively affects debt levels.•Female CEOs strengthen the negative effect of SEW ...preservation on debt financing.•The SEW impact on financial debt is stronger in early generational stages.
This study focuses on heterogeneity in family firms by analyzing whether the non-economic aspects that meet the family’s affective needs, or socioemotional wealth (SEW), influence debt financing. In the context of private family small and medium-sized enterprises (SMEs), our results indicate that family firms which are more concerned about preserving their SEW have lower debt levels (total and financial debt) and that CEO gender plays an important moderating role, with female CEOs strengthening the negative effect of SEW preservation on debt financing. Moreover, when family firms are managed by the first generation, the SEW effect on financial debt is even more negative. The findings are consistent with SEW being the point of reference in family SMEs’ financial decisions, and highlight the importance of the CEO and family generation in charge of the firm as moderators of the relationship between SEW preservation and debt financing.
This review presents and discusses recent advances in the emerging field of "gated nanochemistry", outlining the substantial progress made so far. The development of hybrid mesoporous silica with ...complex tailored pore nanoarchitectures bridges the gap between molecular materials and the requirements of nanodevices for controlled nanoscale chemistry. In the last decade, membranes, particles and thin film porous architectures have been designed, synthesized and selectively modified by molecular, polymeric, organometallic or biologically active groups. The exquisite manipulation of mesopore morphology and interconnection combined with molecular or supramolecular functionalities, and the intrinsic biological compatibility of silica have made these materials a potential platform for selective sensing and drug delivery. The wide
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of these hard-soft architectures permit us to envisage sophisticated intelligent nano-systems that respond to a variety of external stimuli such as pH, redox potential, molecule concentration, temperature, or light. Transduction of these stimuli into a predefined response implies exploiting spatial and physico-chemical effects such as charge distribution, steric constraints, equilibria displacements, or local changes in ionic concentration, just to name a few examples. As expected, this "positional mesochemistry" can be only attained through the concerted control of assembly, surface tailoring and, confinement conditions, thus giving birth to a new class of stimuli-responsive materials with modulable transport properties. As a guiding framework the emerging field of "gated nanochemistry" offers methodologies and tools for building up stimuli-sensitive porous architectures equipped with switchable entities whose transport properties can be triggered at will. The gated nanoscopic hybrid materials discussed here not only herald a new era in the integrative design of "smart" drug delivery systems, but also give the reader a perspective of the promising future in the development of mesoporous platforms that can control mass transport on command through the combination of flexible supramolecular routes, with implications on health, environment and energy.
This Feature Article discusses recent advances in the design of mesoporous silica nanoarchitectures that can control mass transport on command through the combination of flexible supramolecular routes.
ABSTRACT
We present synthetic dust polarization maps of simulated molecular clouds with the goal to systematically explore the origin of the relative orientation of the magnetic field ($\mathbf {B}$) ...with respect to the cloud sub-structure identified in density (n; 3D) and column density (N; 2D). The polarization maps are generated with the radiative transfer code polaris, which includes self-consistently calculated efficiencies for radiative torque alignment. The molecular clouds are formed in two sets of 3D magnetohydrodynamical simulations: (i) in colliding flows (CF), and (ii) in the SILCC-Zoom simulations. In 3D, for the CF simulations with an initial field strength below ∼5 μG, $\mathbf {B}$ is oriented either parallel or randomly with respect to the n-structures. For CF runs with stronger initial fields as well as all SILCC-Zoom simulations, which have an initial field strength of 3 μG, a flip from parallel to perpendicular orientation occurs at high densities of $n_\rm {trans}\, \simeq$ 102–103 cm−3. We suggest that this flip happens if the cloud’s mass-to-flux ratio, μ, is close to or below the critical value of 1. This corresponds to a field strength around 3–5 μG, close to the Galactic average. In 2D, we use the method of Projected Rayleigh Statistics (PRS) to study the relative orientation of $\mathbf {B}$. If present, the flip in orientation occurs in the projected maps at $N_\rm {trans}\, \simeq$ 1021 − 21.5 cm−2. This value is similar to the observed transition value from sub- to supercritical magnetic fields in the interstellar medium. However, projection effects can strongly reduce the predictive power of the PRS method: Depending on the considered cloud or line-of-sight, the projected maps of the SILCC-Zoom simulations do not always show the flip, although it is expected given the 3D morphology. Such projection effects can explain the variety of recently observed field configurations, in particular within a single cloud. Finally, we do not find a correlation between the observed orientation of $\mathbf {B}$ and the N-PDF.
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