Micromechanical model of bovine Haversian bone predicts strain amplification through soft interfaces

Context. Recent observations of brown dwarf spectroscopic variability in the infrared infer the presence of patchy cloud cover. Aims. This paper proposes a mechanism for producing inhomogeneous cloud coverage due to the depletion of cloud particles through the Coulomb explosion of dust in atmospheric plasma regions. Charged dust grains Coulomb-explode when the electrostatic stress of the grain exceeds its mechanical tensile stress, which results in grains below a critical radius a < aCoulcrit being broken up. Methods. This work outlines the criteria required for the Coulomb explosion of dust clouds in substellar atmospheres, the effect on the dust particle size distribution function, and the resulting radiative properties of the atmospheric regions. Results. Our results show that for an atmospheric plasma region with an electron temperature of Te = 10 eV (≈ 105 K), the critical grain radius varies from 10-7 to 10-4 cm, depending on the grains’ tensile strength. Higher critical radii up to 10-3 cm are attainable for higher electron temperatures. We find that the process produces a bimodal particle size distribution composed of stable nanoscale seed particles and dust particles with a ≥ aCoulcrit , with the intervening particle sizes defining a region devoid of dust. As a result, the dust population is depleted, and the clouds become optically thin in the wavelength range 0:1 - 10 μm, with a characteristic peak that shifts to higher wavelengths as more sub-micrometer particles are destroyed. Conclusions. In an atmosphere populated with a distribution of plasma volumes, this will yield regions of contrasting radiative properties, thereby giving a source of inhomogeneous cloud coverage. The results presented here may also be relevant for dust in supernova remnants and protoplanetary disks.PostprintPeer reviewe

To what extent can social cognition models explain adherence to self-care behaviours amongst adolescents with food allergy

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Preparation and characterisation of bioadhesive microparticles comprised of low degree of quaternization trimethylated chitosan for nasal administration: effect of concentration and molecular weight

The Indonesian archipelago is characterized by strong internal tides, which are trapped in the different semi-enclosed seas of the archipelago. Using tidal model results a parameterization of the associated 3d tidal mixing is developed. The resulting average vertical diffusivity is 1.5 cm2/s, which independently agrees with the estimates inferred from observations. Introduced in a regional OGCM, the parameterization improves the water mass characteristics in the different Indonesian seas, suggesting that the horizontal and vertical distributions of the mixing are adequately prescribed. In particular, the salinity maximum of the inflow water is reduced along the main route, mainly in the Dewakang sill area. But also it is erased in the Halmahera and Seram seas, the entrance of the eastern route, so that salty waters doesn't penetrate the Banda Sea. As a result the simulated Indonesian Throughflow Water are in good agreement with observations. <br/

3D mapping of blood vessel networks and cells in COPD and non-COPD lung tissue samples using micro-computed tomography and immunofluorescence

Micro-computed tomography (µCT) is a non-destructive 3D imaging technique used to map tissue microstructure at typical resolutions of 1-10 µm. Correlated with 2D immunofluorescence (IF) microscopy pathophysiologically relevant cells can be identified in 3D. We aimed to investigate 3D networks of small blood vessels (&lt;2mm) and the distribution of immune cells in mild-moderate COPD patients. FFPE peripheral lung samples from 5 non-COPD and 5 COPD patients were scanned using µCT. IF staining for smooth muscle actin, airway epithelium, mast cells and macrophages was digitised, and co-registered with 3D µCT scans. Blood vessels, airways and infiltrating cells were identified semi-automatically by IF in the µCT volume (Fig 1). Quantitative estimates of blood vessel thickness were made, initial modal thickness values were lower in non-COPD (12-25µm) compared to COPD samples (40-60µm). Thousands of macrophages (2100-7200) and mast cells (1700-9000) were localised by IF per tissue section with fewer mast cells (&lt;1500) detected in COPD tissue sections. Combined with the 3D vasculature network the distribution of macrophages and mast cells were found to be similar in both COPD and non-COPD with 70-80% of cells within 2mm of a blood vessel. In summary, we demonstrate an approach to identify, localise and analyse lung networks in 3D and relevant infiltrating cells in human lung disease.

Investigating the nature of small airways disease in mild/moderate COPD: micro-CT analysis of paraffin embedded lung tissue

Rationale: Airflow obstruction, the hallmark characteristic of Chronic Obstructive Pulmonary Disease (COPD) has long been attributed to a combination of small airways disease and emphysematous destruction, however, the relative role of each pathological feature is not well understood. McDonough et al. (NEJM, 2011), reported a significant reduction in terminal bronchiolar number in end-stage COPD compared to controls with normal lung function. Further, the study reported that the loss of terminal bronchioles occurred in regions of lung with and without emphysema, leading to our hypothesis that ‘The obstruction and obliteration of small airways occurs early in mild/moderate COPD and precedes the emphysematous destruction’. Methods: Lung samples were obtained from patients with known pulmonary function undergoing surgical resection for lung cancer or transplant. Lungs were inflated, sliced and sampled prior to formalin fixation and paraffin embedding (FFPE). Eight FFPE cores per patient were randomly sampled throughout the lung and scanned using a Nikon Metrology micro-CT scanner. Volumetric data sets were examined to determine mean linear intercept (Lm), number of terminal (TB) and transitional (TrB) bronchioles per ml of tissue. Image registration was used to precisely locate regions of interest, enabling efficient sectioning and staining with Movat’s Pentachrome for a more comprehensive analysis of airway morphology. Results: Our study demonstrates that micro-CT scans of FFPE cores provide adequate resolution of fine lung architecture when compared to mean linear intercept measurements obtained from matched histological sections (Bland-Altman). We report that the total number of terminal bronchioles is significantly decreased from 6.2±1.1 TB/ml in smokers with normal lung function, to 4.6±1.0 TB/ml in mild/moderate COPD patients and 2.8±1.8 TB/ml in severe COPD. Further, we demonstrate a significant decrease in transitional bronchiolar number from 16.7 ± 7.2 TrB/ml in the control group to 10.0 ± 6.0 TrB/ml in mild/moderate COPD, and 2.1±2.7 TrB/ml in severe COPD. When correlating the number of terminal and transitional bronchioles to Lm, we find that bronchioles are destroyed in tissues where no emphysema is present. Lesions of interest are characterized by histology to further understand the pathological process. Conclusions: Clinical trials and the treatment of COPD have traditionally focused on patients with severe disease and no current pharmacological therapies have been shown to affect long term, lung function decline. Our findings suggest that irreversible pathological events occur in the early stages of disease, emphasizing the importance of early diagnosis and intervention to modify the progression of this debilitating respiratory disorder