Genetic mechanisms of opa gene variation in Neisseria gonorrhoeae

To understand the rates and mechanisms of Neisseria gonorrhoeae opacity (opa) gene variation, the 11 opa genes were amplified independently so that an opa allelic profile could be defined for any isolate from the sequences at each locus. Initial examination of 14 unrelated gonococcal isolates showed that no opa alleles were shared. Analysis of closely related isolates showed these typically shared most opa alleles and so the mechanisms by which recent changes occurred at individual opa loci could be determined. The great majority of changes were due to recombination among existing alleles that either duplicated an opa allele present at another locus or resulted in a mosaic of existing opa alleles. Single nucleotide changes or the insertion/deletion of a single codon also occurred, but few of these events were assigned to mutation, the majority being assigned to localised recombination. Introduction of novel opa genes from co-infecting strains was rare and all but one occurred in the same sexual network. Changes at the eleventh opa locus (opa11) occurred much more rapidly than at other opa loci, almost always differing even between recent sexual contacts. Examination of the neighbouring pilE gene showed that changes at opa11 and pilE often occurred together, although this linkage may not be a causal one. The Opa protein sequences encoded by the opa genes were determined and the regions spanning the two hyper-variable regions (HVR1 and HVR2) were analysed. An almost equal number of Opa protein and opa nucleotide sequences were detected but there was a limited number of HVR combinations, indicating that a large proportion of differences are located elsewhere in the protein. Very few novel HVRs were generated by recombination, even at opa11 where the rate of variation was greatest. Most changes resulted in re-assortment of existing HVRs, most likely due to protein function restriction/benefits

Trapping of oil in an epoxy-based polymer matrix with activated carbon and its effect on tribological behavior

The incorporation of lubricating oil at high levels in the epoxy composite materials makes it possible to obtain materials with low friction and wear. This article evaluates the wear behaviour of an epoxy-based composite obtained by the addition of lubricating oil and activated carbon. An oil content of up to 31wt% is trapped and maintained in the matrix by the presence of activated carbon. The wear experiments are carried out on a pin-on-disk type tribometer. The tests are carried out on pins of different compositions sliding on steel discs (XC48) under dry friction conditions. The effect of various parameters such as speed and loading has been investigated. The wear surfaces are analyzed by using a scanning electron microscope to observe the different wear mechanisms. The results show that the addition of activated carbon made it possible to trap large quantities of oil in the matrix. This decreased greatly the coefficient of friction and increased the capacity of the sample to withstand higher values of sliding velocities and pressures

Scheduling Coordination in a Supply Chain Using Advance Demand Information.

In an environment of mass customization where demand information can be placed in advance with sequencing orders, the question of the best use of this information arises in a supply chain. This situation led the authors to analyze the efficiency of current mechanisms of scheduling coordination when suppliers' processes are not completely reliable. Policies such as periodic replenishment or the kanban system, characterized by a replacement of the items to consume, cannot be exploited effectively with the current rules. This paper presents and justifies new scheduling coordination rules allowing synchronous production in an unreliable environment. This new approach has been benchmarked in the automotive industry as an appropriate method to avoid stockouts and decrease the safety stock.Chaîne logistique; Synchronisation de la production dans une chaîne logistique; kanban; Production synchrone; Point de Pénétration de commande;

Triggered seismicity associated with the 1990 Nicoya, Costa Rica, M-w=7.0 earthquake

The 25 March 1990 (M-w = 7.0) subduction megathrust earthquake that occurred offshore the Nicoya Peninsula, Costa Rica, produced a large number of aftershocks on the subduction plate interface as expected and preceded an unusual sequence of earthquakes 75 km inland that had two periods of significant increase, one at 60-90 days and one near 270 days, following the main shock. This inland sequence of events would not typically fall within the classification of aftershocks given their spatial and temporal distance, and we show here that this sequence was likely triggered by the 25 March main shock. We compute stress changes on representative faults within this inland region using both a simple half-space model as well as with a 2-D finite element model that incorporates variable rheologic properties. The half-space model predicts a minor increase in Coulomb stress changes and a large amount of unclamping in this region, likely enough to cause triggering on the inland right-lateral strike-slip faults. Models that include a viscoelastic response also indicate stress increases that may link to triggering, particularly related to the time delay. Earthquakes on the subduction zone thrust along Costa Rica should be considered in hazard assessments for the inland populated region as several sets of strike-slip faults have been mapped in the fore-arc region

Exploitation of the knowledge of the final demand in the piloting of a logistics chain.

The transition from synchronous supplies to synchronous production represent a possible alternative to the neighbourhood logistics configurations, especially in the automotive industry. It allows to gain, on certain conditions, efficiency and more manoeuvrability faced with a strong variability of the demand on the supply chain. The utilization of the Order Penetration Point (OPP) will introduce problems in piloting production between clients and suppliers processes. This article is based on several working assumptions which form an algorithm for the resolution of this problem resulting from an analysis of two industrial cases with stochastic models.synchronous production; supply chain; anticipation; piloting of flows; order penetration point; kanban;

Determination Of Lignin Degradation Products By GC-MS And Thermal Carbon Analysis (tca)

A novel analysis method of lignin and its degradation products was developed based primarily on thermal desorption and pyrolysis coupled with carbon quantification and speciation. Gas chromatography-mass spectrometry (GC-MS) is a traditional method for characterization of the volatile product fraction, however the volatile (thermal desorption) fraction usually contributes less than 10%wt. of the overall product yield. The unique properties of thermal carbon analysis (TCA) allow not only for the analysis of the thermal desorption fraction (200–300 Ñ), which may further be compared to the GC-MS results, but also for the analysis of higher molecular weight oligomers evolving at pyrolytic temperatures (400–890 Ñ). In addition, using an oxygenation step (550–890 Ñ in the presence of oxygen) as the final step, it is possible to evolve the rigid cross-linked oligomers, inorganic carbon and other remaining carbon forms and close the mass balance. The key TCA parameters, drying and purging time, were evaluated in different solvent systems in order to ensure a near-100% recovery of all the lignin degradation products. Furthermore, other factors potentially affecting the TCA profile, such as sample loading, interactions with the sampling surface and initial step temperature, were evaluated. In the second main part of this study, the lignin hydrotreatment reactions performed in a lab scale, static batch reactor were evaluated using both TCA and GC-MS. The effect of the reaction temperature and the presence of a catalyst, particularly different nickel based catalysts, zeolites, activated carbon and silica-alumina, were studied. The overall yield of monomeric and dimeric degradation products increased with temperature. A promising result was obtained at reactions conducted at 300 Ñ in the presence of LaO doped activated carbon and zeolite catalysts, where the total yield of volatiles was 5.3 and 6.3%wt., respectively. In addition, a significant amount of dimers over 1.0%wt. was produced. A good agreement between the GC-MS and thermal desorption fraction of TCA was obtained. Combining the overall TCA yield of carbon with gravimetric data of unreacted lignin lead to a successful mass balance closure. Ultimately, a complete mass balance closure was also obtained for the solid alkali lignin analyzed by TCA with the newly developed protocol and the results were compared with TGA, proving the excellent TCA analytical performance and selectivity towards the carbon containing species. Another parallel comparison was made using Pyrolysis-GC-MS in order to identify the lignin degradation products contributing to the carbon evolved in each temperature fraction

Electoral competitiveness in competitive authoritarianism in Latin America 1990-2014

Elections in competitive authoritarian regimes have become a major focus of comparative research. However, existing research mostly focuses on large-N comparative studies with older cases and data. Therefore, the conclusions of these studies typically only have a fairly limited explanatory potential. A number of authors thus suggest turning our attention to studies with small and middle-N, which -thanks to closer interaction with data- can help improve the explanatory ability. The aim of this study is to react to this situation and offer an explanation of the varying degree of electoral competitiveness in competitive authoritarianism in Latin America. For that purpose, this study compares 41 cases of elections that were carried out between 1990 and 2014, using regression analysis and qualitative comparative analysis (QCA). This study uses the data from the Varieties of Democracy (V-DEM) project and tries to either provide more accurate conclusions than some of the previous researches or to disprove these conclusions altogether. The results highlight the importance of economic growth, concurrent elections, opposition party ban, cohesion of the opposition and media censorship. These findings are in discrepancy with previous research which rather put structural factors in the back seat and considered actors' behaviour to be the key factors. What is even more interesting, though, is the fact that the two most influential structural explanations usually mentioned with respect to competitive authoritarianism, i.e. natural resources rent and economic statism, are proved as rather irrelevant in Latin America’s context

Freezing and thawing resistance of slag alkali activated concrete with different activators

The frost resistance of alkali activated materials is often considered very good. But some opposing results have also been recorded. Despite the good mechanical properties of some slag-alkaline concretes their frost resistance was found bad for field application. One of the reason for the explanation of the discrepancy of the results may be a different composition of the alkaline activator. Very often the content of Na2O (N) or K2O (K) is mentioned as the basic characteristic of an activator. But if water glass is used as an activator the content of SiO2 (S) is also very important. Please click Additional Files below to see the full abstract

Cali Centered Publication

Graphic Desig

Decolonizing the histories of Helen Hunt Jackson and Gertrude Simmons Bonnin.

What is decolonization and how does it work? The concept of decolonization surfaced during "the global Indigenous activism in the 1970s." Although the idea is not new, it has been given little attention by mainstream historians. A discussion of the meaning of decolonization begins with an understanding that colonization means to settle in a colony or colonies. For example, England and Spain began establishing colonies on the lands of the Indigenous Nations of the Americas in the 16th and 17th centuries. Thus, the United States began as a loosely united group of colonies making decolonization a logical consequence. As such, decolonization means to remove or mitigate the consequences of colonization. According to Susan A. Miller (Seminole), "decolonization is a process designed to shed and recover from the ill effects of colonization." In this thesis, I utilize case studies of two women to demonstrate how decolonizing history using an Indigenous lens can construct a more comprehensive history and produce a distinct narrative from a Native American perspective. I argue using this methodology recasts the activism of Helen Hunt Jackson and Gertrude Simmons Bonnin (Yankton Nakota) as the progenitor to modern Native American rights movements. The political activism of Jackson and Bonnin resides within literary journals shadowed by analyses of their fiction and poetry. Utilizing a different perspective revealed the stories of two women whose work made a significant impact on relations between the United States government and Native American nations that was generally less celebrated among historians. The object of this research project is to use an Indigenous perspective to decolonize and reclaim the histories of Helen Hunt Jackson and Gertrude Simmons Bonnin (Yankton Nakota) and their activism for Native American rights. The historical importance of the reform work of both women went unnoticed for a few decades, but the activism of the 1960s resurrected their legacy. Preliminary research indicated scholars focused primarily on the literary achievements of these Victorian Age women not their efforts to change the assimilation policies of the U.S. government. American historians infrequently accept Helen Jackson as a historian even though the production of her book A Century of Dishonor (1881) required hours of work analyzing primary source documents such as survey maps and treaties. Some Native American scholars put Jackson in the company of people called "do-gooders" or those people who supported the practice of assimilation as the best outcome for Native American tribes. In recent decades, scholars such as P. Jane Hafen (Taos Pueblo) began producing work that focused on the political importance of Bonnin's activism. Robert Warrior (Osage) labeled her as pro-assimilation because she worked for the Society of American Indians (SAI) whose constituency was comprised of Native American leaders that believed assimilation was the best way for Native Americans to articulate with the dominant culture. However, further analysis found that Gertrude left the SAI because she did not agree with her peers. This project produced a manuscript that provides an example of how to apply the principles of Indigenous discourse, as set forth by Susan Miller specifically regarding decolonization. This researcher's perspective saw Jackson and Bonnin's activism as the progenitor of modern day Native American rights movements. Jackson produced the first investigative effort to catalogue the broken treaty provisions and land misappropriations inflicted on Native American tribes by the U.S. government. Her enduring non-literary legacy was the work she did as an Indian agent for the Mission Indians of California where she worked to ensure the government treated the tribes equitably. Among Gertrude Bonnin's many accomplishments, her last and most significant was the creation of the National Council of American Indians that she co-founded with her husband in 1926. This organization preceded the modern day National Congress of American Indians. Thus, the result of this project is a decolonized narrative focused on the reform work of Helen Hunt Jackson and Gertrude Simmons Bonnin. Decolonizing the history of two very different women with synchronistic goals may encourage other historians whether Native American, western, or American to present alternative perspectives in the histories they write