89 research outputs found
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The biomechanics of amnion rupture: an X-ray diffraction study
Pre-term birth is the leading cause of perinatal and neonatal mortality, 40% of which are attributed to the pre-term premature rupture of amnion. Rupture of amnion is thought to be associated with a corresponding decrease in the extracellular collagen content and/or increase in collagenase activity. However, there is very little information concerning the detailed organisation of fibrillar collagen in amnion and how this might influence rupture. Here we identify a loss of lattice like arrangement in collagen organisation from areas near to the rupture site, and present a 9% increase in fibril spacing and a 50% decrease in fibrillar organisation using quantitative measurements gained by transmission electron microscopy and the novel application of synchrotron X-ray diffraction. These data provide an accurate insight into the biomechanical process of amnion rupture and highlight X-ray diffraction as a new and powerful tool in our understanding of this process
Designing a Process Mining-Enabled Decision Support System for Business Process Standardization in ERP Implementation Projects
Process standardization allows to optimize ERP systems and is a nec-essary step prior to ERP implementation projects. Traditional approaches to standardizing business processes are based on manually created "de-jure" process models, which are distorted, error-prone, simplistic, and often deviating from process reality. Theoretically embedded in the organizational contingency theory as kernel theory, this paper employs a design science approach to design a process mining-enabled decision support system (DSS) which combines bottom-up process mining models with manually added top-down standardization infor-mation to recommend a suitable standard process specification from a repository. Extended process models of the as-is process are matched against a repository of best-practice standard process model using an attributebased process similarity matching algorithm. Thus, the DSS aims to reduce the overall costs of process standardization, to optimize the degree of fit between the organization and the implemented processes, and to minimize the degree of organizational change re-quired in standardization and ERP implementation projects. This paper imple-ments a working prototype instantiation in the open-source process analytics platform Apromore based on a real-life event log and standardization attributes for the Purchase-to-Pay and Order-to-Cash processes from three SAP R/3 ERP systems at the industry partner
Sources and Sinks of Diversification and Conservation Priorities for the Mexican Tropical Dry Forest
Elucidating the geographical history of diversification is critical for inferring where future diversification may occur and thus could be a valuable aid in determining conservation priorities. However, it has been difficult to recognize areas with a higher likelihood of promoting diversification. We reconstructed centres of origin of lineages and identified areas in the Mexican tropical dry forest that have been important centres of diversification (sources) and areas where species are maintained but where diversification is less likely to occur (diversity sinks). We used a molecular phylogeny of the genus Bursera, a dominant member of the forest, along with information on current species distributions. Results indicate that vast areas of the forest have historically functioned as diversity sinks, generating few or no extant Bursera lineages. Only a few areas have functioned as major engines of diversification. Long-term preservation of biodiversity may be promoted by incorporation of such knowledge in decision-making
The Dynamics of Ca2+ Ions within the Solvation Shell of Calbindin D9k
The encounter of a Ca2+ ion with a protein and its subsequent
binding to specific binding sites is an intricate process that cannot be fully
elucidated from experimental observations. We have applied Molecular Dynamics to
study this process with atomistic details, using Calbindin D9k (CaB) as a model
protein. The simulations show that in most of the time the Ca2+
ion spends within the Debye radius of CaB, it is being detained at the 1st and
2nd solvation shells. While being detained near the protein, the diffusion
coefficient of the ion is significantly reduced. However, due to the relatively
long period of detainment, the ion can scan an appreciable surface of the
protein. The enhanced propagation of the ion on the surface has a functional
role: significantly increasing the ability of the ion to scan the protein's
surface before being dispersed to the bulk. The contribution of this mechanism
to Ca2+ binding becomes significant at low ion concentrations,
where the intervals between successive encounters with the protein are getting
longer. The efficiency of the surface diffusion is affected by the distribution
of charges on the protein's surface. Comparison of the Ca2+
binding dynamics in CaB and its E60D mutant reveals that in the wild type (WT)
protein the carboxylate of E60 function as a preferred landing-site for the
Ca2+ arriving from the bulk, followed by delivering it to
the final binding site. Replacement of the glutamate by aspartate significantly
reduced the ability to transfer Ca2+ ions from D60 to the final
binding site, explaining the observed decrement in the affinity of the mutated
protein to Ca2+
Platelet-Activating Factor Induces TLR4 Expression in Intestinal Epithelial Cells: Implication for the Pathogenesis of Necrotizing Enterocolitis
Necrotizing enterocolitis (NEC) is a leading cause of morbidity and mortality in neonatal intensive care units, however its pathogenesis is not completely understood. We have previously shown that platelet activating factor (PAF), bacteria and TLR4 are all important factors in the development of NEC. Given that Toll-like receptors (TLRs) are expressed at low levels in enterocytes of the mature gastrointestinal tract, but were shown to be aberrantly over-expressed in enterocytes in experimental NEC, we examined the regulation of TLR4 expression and signaling by PAF in intestinal epithelial cells using human and mouse in vitro cell lines, and the ex vivo rat intestinal loop model. In intestinal epithelial cell (IEC) lines, PAF stimulation yielded upregulation of both TLR4 mRNA and protein expression and led to increased IL-8 secretion following stimulation with LPS (in an otherwise LPS minimally responsive cell line). PAF stimulation resulted in increased human TLR4 promoter activation in a dose dependent manner. Western blotting and immunohistochemical analysis showed PAF induced STAT3 phosphorylation and nuclear translocation in IEC, and PAF-induced TLR4 expression was inhibited by STAT3 and NFκB Inhibitors. Our findings provide evidence for a mechanism by which PAF augments inflammation in the intestinal epithelium through abnormal TLR4 upregulation, thereby contributing to the intestinal injury of NEC
A Tale of Four “Carp”: Invasion Potential and Ecological Niche Modeling
. We assessed the geographic potential of four Eurasian cyprinid fishes (common carp, tench, grass carp, black carp) as invaders in North America via ecological niche modeling (ENM). These “carp” represent four stages of invasion of the continent (a long-established invader with a wide distribution, a long-established invader with a limited distribution, a spreading invader whose distribution is expanding, and a newly introduced potential invader that is not yet established), and as such illustrate the progressive reduction of distributional disequilibrium over the history of species' invasions.We used ENM to estimate the potential distributional area for each species in North America using models based on native range distribution data. Environmental data layers for native and introduced ranges were imported from state, national, and international climate and environmental databases. Models were evaluated using independent validation data on native and invaded areas. We calculated omission error for the independent validation data for each species: all native range tests were highly successful (all omission values <7%); invaded-range predictions were predictive for common and grass carp (omission values 8.8 and 19.8%, respectively). Model omission was high for introduced tench populations (54.7%), but the model correctly identified some areas where the species has been successful; distributional predictions for black carp show that large portions of eastern North America are at risk.ENMs predicted potential ranges of carp species accurately even in regions where the species have not been present until recently. ENM can forecast species' potential geographic ranges with reasonable precision and within the short screening time required by proposed U.S. invasive species legislation
Competition for space can drive the evolution of dormancy in a temporally invariant environment
Membrainy: a ‘smart’, unified membrane analysis tool
BACKGROUND: The study of biological membranes using Molecular Dynamics has become an increasingly popular means by which to investigate the interactions of proteins, peptides and potentials with lipid bilayers. These interactions often result in changes to the properties of the lipids which can modify the behaviour of the membrane. Membrainy is a unified membrane analysis tool that contains a broad spectrum of analytical techniques to enable: measurement of acyl chain order parameters; presentation of 2D surface and thickness maps; determination of lateral and axial headgroup orientations; measurement of bilayer and leaflet thickness; analysis of the annular shell surrounding membrane-embedded objects; quantification of gel percentage; time evolution of the transmembrane voltage; area per lipid calculations; and quantification of lipid mixing/demixing entropy. RESULTS: Each analytical component within Membrainy has been tested on a variety of lipid bilayer systems and was found to be either comparable to or an improvement upon existing software. For the analytical techniques that have no direct comparable software, our results were confirmed with experimental data. CONCLUSIONS: Membrainy is a user-friendly, intelligent membrane analysis tool that automatically interprets a variety of input formats and force fields, is compatible with both single and double bilayers, and capable of handling asymmetric bilayers and lipid flip-flopping. Membrainy has been designed for ease of use, requiring no installation or configuration and minimal user-input to operate
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