Search results for "Gradation"
showing 10 items of 1275 documents
Sequencing and analysis of the gene encoding the α-toxin of Clostridium novyi proves its homology to toxins A and B of Clostridium difficile
1995
A library of total Clostridium novyi DNA was established and screened for the alpha-toxin gene (tcn alpha) by hybridization with oligonucleotides derived from a partial N-terminal sequence and by using specific antisera. Overlapping subgenic tcn alpha fragments were isolated and subsequently the total sequence of tcn alpha was determined. The 6534 nucleotide open reading frame encodes a polypeptide of M(r) 250,166 and pI 5.9. The N-terminal alpha-toxin (Tcn alpha) sequence MLITREQLMKIASIP determined by Edman degradation confirmed the identity of the reading frame and the assignment of the translation start point. The toxin is not modified posttranslationally at its N-terminus nor does it co…
Preparation, characterization and hydrolytic degradation of PLA/PCL co-mingled nanofibrous mats prepared via dual-jet electrospinning
2017
Abstract PLA/PCL co-mingled nanofibrous mats were prepared via multi-jet electrospinning. The concentration of PLA and PCL in the co-mingled mats were controlled by changing the flow rate of the two polymer solutions. The amount of PLA and PCL in the co-mingled nanofibrous mats was monitored by UV–Vis measurements through a colored dye added to PLA and by FTIR-ATR analysis. Morphology and mechanical properties of the nanofibrous mats were respectively examined by scanning electron microscopy (SEM) and tensile tests. Water contact angles measurements were also carried out in order to investigate the wettability of the materials. Finally, the hydrolytic degradation of the mats in buffer solut…
Effect of kind and content of organo-modified clay on properties of PET nanocomposites
2011
In this work we report the properties of nanocomposite based on PET with two different samples of organically modified montmorillonites. In particular, we studied the effect of the filler concentration on morphology, rheology, and mechanical performance, focusing our attention on the effect of the degradation phenomena of the clay modifiers. The results indicate that at low clay level the morphology achieved is mainly intercalated. On increasing the filler level, coalescence and/or bad defragmentation phenomena induce a coarser morphology, as confirmed by XRD, SEM, and TEM observations. When a more polar organic modifier is used to modify the clay, the particle adhesion and distribution is …
External effects of domestic regulations: comparing internal and international barriers to trade
2001
Abstract In a world in which barriers to trade at all levels—international and internal—are mostly a by-product of the implementation by governments of different regulatory policies to deal with “domestic” or “local” problems such as environmental degradation, health, and labor standards, the article purports to show how the mechanisms that are set in motion by the operation of competition among the governments inhabiting the different jurisdictional tiers of federal countries lead to outcomes that are different from those generated by the ‘agreed-upon’ rules that govern the relations of national governments with each other in matters of international trade.
Factors Behind Junk DNA in Bacteria
2012
Although bacterial genomes have been traditionally viewed as being very compact, with relatively low amounts of repetitive and non-coding DNA, this view has dramatically changed in recent years. The increase of available complete bacterial genomes has revealed that many species present abundant repetitive DNA (i.e., insertion sequences, prophages or paralogous genes) and that many of these sequences are not functional but can have evolutionary consequences as concerns the adaptation to specialized host-related ecological niches. Comparative genomics analyses with close relatives that live in non-specialized environments reveal the nature and fate of this bacterial junk DNA. In addition, the…
Restoration of Videos Degraded by Local Isoplanatism Effects in the Near-Infrared Domain
2008
When observing a scene horizontally at a long distance in the near-infrared domain, degradations due to atmospheric turbulence often occur. In our previous work, we presented two hybrid methods to restore videos degraded by such local perturbations. These restoration algorithms take advantages of a space-time Wiener filter and a space-time regularization by the Laplacian operator. Wiener and Laplacian regularization results are mixed differently depending on the distance between the current pixel and the nearest edge point. It was shown that a gradation between Wiener and Laplacian areas improves results quality, so that only the algorithm using a gradation will be used in this article. In …
Statistics-driven Development of OBD Systems: An Overview
2006
Automotive on-board diagnostic (OBD) systems are designed to keep critical components under control during vehicle functioning, and to alert the driver in case of severe malfunctions. OBD systems aimed at reducing polluting emissions are mandatory on new motor vehicles. Some research projects conducted in cooperation between universities and the automotive industry have been quite successful in terms of knowledge advancement and industrial gain. An updated overview of the adopted methodologies and results obtained are given in this article. Such results can be valuable for both theorists and practitioners, since they witness the use of statistics as a powerful catalyst of technical progress…
Conservation genetics of an endemic from the Mediterranean Basin: high genetic differentiation but no genetic diversity loss from the last population…
2013
The Mediterranean Basin is a biodiversity hotspot, housing > 11.000 narrowly endemic plant species, many of which are declining due to mass tourism and agricultural intensification. To investigate the genetic resource impacts of ongoing habitat loss and degradation, we characterized the genetic variation in the last known populations of Leopoldia gussonei, a self-compatible endangered Sicilian Grape Hyacinth numbering less than 3,000 remaining individuals, using AFLP. Results demonstrated significant genome-wide genetic differentiation among all extant populations (I broken vertical bar(ST) = 0.05-0.56), and genetic clustering according to geographic location. Gene diversity was fairly c…
The superior effect of nature based solutions in land management for enhancing ecosystem services
2017
The rehabilitation and restoration of land is a key strategy to recover services -goods and resources- ecosystems offer to the humankind. This paper reviews key examples to understand the superior effect of nature based solutions to enhance the sustainabilit y of catchment systems by promoting desirable soil and landscape functions. The use of concepts such as connectivity and the theory of system thinking framework allowed to review coastal and river management as a guide to evaluate other strategies to achieve sustainability. In land management NBSs are not mainstream management. Through a set of case studies: organic farming in Spain; rewilding in Slovenia; land restoration in Iceland, s…
Fighting carbon loss of degraded peatlands by jump-starting ecosystem functioning with ecological restoration
2015
Degradation of ecosystems is a great concern on the maintenance of biodiversity and ecosystem services. Ecological restoration fights degradation aiming at the recovery of ecosystem functions such as carbon (C) sequestration and ecosystem structures like plant communities responsible for the C sequestration function. We selected 38 pristine, drained and restored boreal peatland sites in Finland and asked i) what is the long-term effect of drainage on the peatland surface layer C storage, ii) can restoration recover ecosystem functioning (surface layer growth) and structure (plant community composition) and iii) is the recovery of the original structure needed for the recovery of ecosystem f…