1,658 research outputs found

    Emphysema

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    Emphysema (Greek word meaning to inflate/to blow) is an increase in the size of airspace distal to the terminal bronchiolus, that is, hyperinflation of the alveoli due to the destruction of the gas-exchanging structures: alveolar walls, alveolar ducts, and respiratory bronchioles with coalescence of airspaces into the abnormal, much larger airspaces. The main consequences are the reduction of alveolar surface for gas exchange and the chronic obstructive pulmonary disease due to the destruction and disappearance of respiratory bronchioles with decreased total small airway diameter sum. Both decreased alveolar surface for gas exchange and chronic obstructive pulmonary disease lead to difficulty in breathing with dyspnea varying from mild to very severe. Two main pathohistologic types of emphysema are centriacinar and panacinar. Centriacinar emphysema involves the central portion of the acinus, and inflation mainly involves respiratory bronchioles and adjacent alveoli, and not all alveoli inside the acinus are involved. Panacinar (panlobular) emphysema is characterized by uniform enlargement and destruction of alveoli throughout the entire acinus. The panacinar emphysema is rare and its most common cause is hereditary alpha-1 antitrypsin deficiency. The centriacinar emphysema is the most frequent emphysema. It is mainly caused by smoking but also by coal dust exposure and advanced age

    The chloroplast import receptor Toc34 functions as preprotein-regulated GTPase

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    Toc34 is a protein of the chloroplast outer envelope membrane that acts as receptor for preproteins containing a transit sequence. The recognition of preproteins by Toc34 is regulated by GTP binding and phosphorylation. The phosphorylation site of Toc34 is located at serine 113, close to the postulated triphosphate binding site. This can explain the down-regulation of Toc34 by phosphorylation, resulting in the loss of GTP binding. Vice versa, GTP but not GDP binding of Toc34 influences the phosphorylation. The nucleotide specificity of Toc34 is not only determined by the classical nucleotide binding domains but by a non-typical region at the N-terminus of the protein. As a result, the GTP binding properties are unusual, since the triphosphate moiety of GTP is bound with higher affinity than the purine base. Purified Toc34 hydrolyses GTP at a low rate, which could regulate the receptor function. The rate of hydrolysis is greatly stimulated by a precursor protein

    Effects of Boundary Conditions on Single-File Pedestrian Flow

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    In this paper we investigate effects of boundary conditions on one dimensional pedestrian flow which involves purely longitudinal interactions. Qualitatively, stop-and-go waves are observed under closed boundary condition and dissolve when the boundary is open. To get more detailed information the fundamental diagrams of the open and closed systems are compared using Voronoi-based measurement method. Higher maximal specific flow is observed from the pedestrian movement at open boundary condition

    Flocking and turning: a new model for self-organized collective motion

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    Birds in a flock move in a correlated way, resulting in large polarization of velocities. A good understanding of this collective behavior exists for linear motion of the flock. Yet observing actual birds, the center of mass of the group often turns giving rise to more complicated dynamics, still keeping strong polarization of the flock. Here we propose novel dynamical equations for the collective motion of polarized animal groups that account for correlated turning including solely social forces. We exploit rotational symmetries and conservation laws of the problem to formulate a theory in terms of generalized coordinates of motion for the velocity directions akin to a Hamiltonian formulation for rotations. We explicitly derive the correspondence between this formulation and the dynamics of the individual velocities, thus obtaining a new model of collective motion. In the appropriate overdamped limit we recover the well-known Vicsek model, which dissipates rotational information and does not allow for polarized turns. Although the new model has its most vivid success in describing turning groups, its dynamics is intrinsically different from previous ones in a wide dynamical regime, while reducing to the hydrodynamic description of Toner and Tu at very large length-scales. The derived framework is therefore general and it may describe the collective motion of any strongly polarized active matter system.Comment: Accepted for the Special Issue of the Journal of Statistical Physics: Collective Behavior in Biological Systems, 17 pages, 4 figures, 3 video

    Wide-field LOFAR-LBA power-spectra analyses: Impact of calibration, polarization leakage and ionosphere

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    Contamination due to foregrounds (Galactic and Extra-galactic), calibration errors and ionospheric effects pose major challenges in detection of the cosmic 21 cm signal in various Epoch of Reionization (EoR) experiments. We present the results of a pilot study of a field centered on 3C196 using LOFAR Low Band (56-70 MHz) observations, where we quantify various wide field and calibration effects such as gain errors, polarized foregrounds, and ionospheric effects. We observe a `pitchfork' structure in the 2D power spectrum of the polarized intensity in delay-baseline space, which leaks into the modes beyond the instrumental horizon (EoR/CD window). We show that this structure largely arises due to strong instrumental polarization leakage (∼30%\sim30\%) towards {Cas\,A} (∼21\sim21 kJy at 81 MHz, brightest source in northern sky), which is far away from primary field of view. We measure an extremely small ionospheric diffractive scale (rdiff≈430r_{\text{diff}} \approx 430 m at 60 MHz) towards {Cas\,A} resembling pure Kolmogorov turbulence compared to rdiff∼3−20r_{\text{diff}} \sim3 - 20 km towards zenith at 150 MHz for typical ionospheric conditions. This is one of the smallest diffractive scales ever measured at these frequencies. Our work provides insights in understanding the nature of aforementioned effects and mitigating them in future Cosmic Dawn observations (e.g. with SKA-low and HERA) in the same frequency window.Comment: 20 pages, 11 figures, accepted for publication in MNRA

    Pulmonary arteriole gene expression signature in idiopathic pulmonary fibrosis

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    Matrix metalloproteinase-2 (MMP-2) and-9 (MMP-9) gene variants and microvascular complications in type 2 diabetes patients

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    AbstractVascular complications are the leading cause of increased morbidity and mortality of diabetic patients. It has been postulated that matrix metalloproteinases MMP-2 and MMP-9, zinc-dependent endopeptidases through remodeling of the extracellular matrix, can contribute to the onset and progression of diabetic vascular complications. The aim of our study was to assess whether there is a major difference in single nucleotide polymorphisms in the MMP-2 (at position -1306C˃T) and MMP-9 (at position -1562C˃T) gene in type 2 diabetic patients and healthy controls and to determine whether there is an association of these gene variants with the presence of microvascular complications in diabetic patients. Our study included 102 type 2 diabetes patients and a control group which was comprised of 56 healthy controls. All diabetic patients were screened for microvascular diabetes complications. Genotypes were detected by polymerase chain reactions followed by restriction analyses with specific endonucleases and their frequencies were determined. The MMP-2 variant -1306C>T showed a negative correlation with type 2 diabetes (p=0.028). It was also shown that the presence of the -1306C allele increases the probability of developing type 2 diabetes. This was a 2.2 fold increase and that the -1306 T allele has a protective role in regards t

    Bioaugmentation of sewage sludge with Trametes versicolor in solid-phase biopiles produces degradation of pharmaceuticals and affects microbial communities

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    The use of sludge (biosolids) in land application may contribute to the spread of organic micropollutants as wastewater treatments do not completely remove these compounds. Therefore, the development of alternative strategies for sludge treatment is a matter of recent concern. The elimination of pharmaceuticals at pre-existent concentrations from sewage sludge was assessed, for the first time, in nonsterile biopiles by means of fungal bioaugmentation with Trametes versicolor (BTV-systems) and compared with the effect of autochthonous microbiota (NB-systems). The competition between the autochthonous fungal/bacterial communities and T. versicolor was studied using denaturing gradient gel electrophoresis (DGGE) and the cloning/ sequencing approach. An inhibitory effect exerted by T. versicolor over bacterial populations was suggested. However, after 21 days, T. versicolor was no longer the main taxon in the fungal communities. The elimination profiles revealed an enhanced removal of atorvastatin-diclofenac-hydrochlorothiazide (during the whole treatment) and ranitidine-fenofibrate (at short periods) in the BTV biopiles in respect to NB biopiles, coincident with the presence of the fungus. For ibuprofen-clarithromycin-furosemide, the elimination profiles were similar irrespective of the system, and with carbamazepine no significant degradation was obtained. The results suggest that a fungal treatment with T. versicolor could be a promising process for the remediation of some pharmaceuticals in complex matrices such as biosolids.Portuguese-Spanish action E51/1
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