Search results for "Barrier"
showing 10 items of 678 documents
Strategic Analysis Tools Application at SMEs in Ecuador
2015
This article explores the nature and scope of Strategic Analysis Tools (SAT) application in SMEs located in emerging countries such as Ecuador (where there are no formal studies on the subject). It is intended to assess which of the instruments utilized by these firms may contribute to formulate strategic options and which of them create awareness of relevant risks or distress specifically about continuity concerning their operations. Through the application of a survey to an intentional sample-selection of SMEs in Quito-Ecuador we analyzed the consciousness over these instruments to facilitate the creation of strategic options, their contribution to assess their competitive position and th…
Gd-DTPA in blood-ocular barrier damage: a new diagnostic tool for future application in MRI?
1995
The blood-brain barrier is not the only neuroepithelial blood filter in the body: the eye too is supported by a highly specialised microvascular filter, the so-called blood-ocular barrier (BOB). The BOB is actually divided into a blood-aqueous (BAB) and a blood-retinal (BRB) barrier, filtering the aqueous fluid and biological supplies, respectively, to the retina. The authors’ purpose was to study the possibility of imaging BAB or BRB damage by contrast-enhanced MRI: they examined 21 patients with a 0.5 T system and surface coil. Despite the normal findings in the damaged eyes immediately after a Gd-DTPA bolus, delayed contrast-enhanced MRI was able to show focal or diffuse barrier damage.
Preclinical Retinal Neurodegeneration in a Model of Multiple Sclerosis
2012
Neurodegeneration plays a major role in multiple sclerosis (MS), in which it is thought to be the main determinant of permanent disability. However, the relationship between the immune response and the onset of neurodegeneration is still a matter of debate. Moreover, recent findings in MS patients raised the question of whether primary neurodegenerative changes can occur in the retina independent of optic nerve inflammation. Using a rat model of MS that frequently leads to optic neuritis, we have investigated the interconnection between neurodegenerative and inflammatory changes in the retina and the optic nerves with special focus on preclinical disease stages. We report that, before manif…
Expression of the ALS-causing variant hSOD1G93A leads to an impaired integrity and altered regulation of claudin-5 expression in an in vitro blood–sp…
2015
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by progressive paralysis due to the loss of primary and secondary motor neurons. Mutations in the Cu/Zn-superoxide dismutase (SOD1) gene are associated with familial ALS and to date numerous hypotheses for ALS pathology exist including impairment of the blood–spinal cord barrier. In transgenic mice carrying mutated SOD1 genes, a disrupted blood–spinal cord barrier as well as decreased levels of tight junction (TJ) proteins ZO-1, occludin, and claudin-5 were detected. Here, we examined TJ protein levels and barrier function of primary blood–spinal cord barrier endothelial cells of presymptomatic hSOD1G93…
Scanning tunneling microscopy and spectroscopy of Mo clusters grown on TiO2(110).
2007
Molybdenum was deposited in two steps (3 eq. ML and 1 eq. ML) on the light blue rutile TiO2 10) (1 x 1) surface at room temperature, each Mo deposition cycle being followed by an annealing up to 950-1000 K. This procedure was found to lead to formation of separated clusters having a size in very wide range (1-20 nm). Scanning tunneling microscopy showed a dependence of the cluster morphology as a function of the size. The scanning tunneling spectra of Mo clusters was studied as a function of cluster dimensions and discussed in comparison with photoelectron spectroscopy results previously obtained for homogeneous Mo films. The dI/d V curves do not display the valence band structure of deposi…
Non-cross-linked porcine-based collagen I-III membranes do not require high vascularization rates for their integration within the implantation bed: …
2012
There are conflicting reports concerning the tissue reaction of small animals to porcine-based, non-cross-linked collagen I-III membranes/matrices for use in guided tissue/bone regeneration. The fast degradation of these membranes/matrices combined with transmembrane vascularization within 4 weeks has been observed in rats compared with the slow vascularization and continuous integration observed in mice. The aim of the present study was to analyze the tissue reaction to a porcine-based non-cross-linked collagen I-III membrane in mice. Using a subcutaneous implantation model, the membrane was implanted subcutaneously in mice for up to 60 days. The extent of scaffold vascularization, tissue …
Coulomb Corrections in Proton-Deuteron Scattering
1976
We present the first calculations of differential cross sections for elastic proton-deuteron scattering using a three-body formalism which correctly takes into account the Coulomb repulsion between the two protons.
Barriere verdi di protezione acustica e abbattimento polveri lungo le vie di grande comunicazione
2014
Barriere verdi di protezione acustica e abbattimento polveri lungo le vie di grande comunicazione
L'impianto, la gestione e la valorizzazione multifunzionale dei boschi periurbani
2014
I boschi periurbani, come tutti gli spazi verdi prossimi agli agglomerati urbani, migliorano le condizioni ambientali e la qualità dell'aria, contribuiscono alla conservazione della biodiversità, possono favorire l'aggregazione sociale. I boschi prossimi ai centri urbani rivestono inoltre un ruolo importante dal punto di vista paesaggistico e turistico e contribuiscono a contrastare i cambiamenti climatici. Questa pubblicazione, redatta con il supporto tecnico-scientifico dell'Accademia italiana di scienze forestali di Firenze, si propone di fornire linee guida per la progettazione, la realizzazione e la gestione dei boschi periurbani e delle fasce verdi nelle aree prossime agli agglomerati…
Le simbiosi in ambiente marino
2011
L’adattamento e la conseguente selezione naturale ha prodotto un’infinita varietà di organismi viventi, ciascuno dotato di peculiari caratteristiche, per consentire ad ogni specie di utilizzare l’ambiente in cui vive. I membri che formano le comunità naturali creano tra di essi dei complessi sistemi fatti di rapporti di competizione e di cooperazione. Questi, contribuiscono ad assicurare l’evoluzione delle specie nell’efficace opera di utilizzazione dell’ambiente. Nell’ambito delle relazioni tra individui di specie diverse esistono alcune singolari associazioni che si evolvono insieme, stabilendo un legame intimo e duraturo che comporta un elevato grado di specializzazione da parte dei cont…