16,728 research outputs found
The Social Amoeba <i>Polysphondylium pallidum</i> Loses Encystation and Sporulation, but Can Still Erect Fruiting Bodies in the Absence of Cellulose
No full textAmoebas and other freely moving protists differentiate into walled cysts when exposed to stress. As cysts, amoeba pathogens are resistant to biocides, preventing treatment and eradication. Lack of gene modification procedures has left the mechanisms of encystation largely unexplored. Genetically tractable Dictyostelium discoideum amoebas require cellulose synthase for formation of multicellular fructifications with cellulose-rich stalk and spore cells. Amoebas of its distant relative Polysphondylium pallidum (Ppal), can additionally encyst individually in response to stress. Ppal has two cellulose synthase genes, DcsA and DcsB, which we deleted individually and in combination. Dcsa- mutants formed fruiting bodies with normal stalks, but their spore and cyst walls lacked cellulose, which obliterated stress-resistance of spores and rendered cysts entirely non-viable. A dcsa-/dcsb- mutant made no walled spores, stalk cells or cysts, although simple fruiting structures were formed with a droplet of amoeboid cells resting on an sheathed column of decaying cells. DcsB is expressed in prestalk and stalk cells, while DcsA is additionally expressed in spores and cysts. We conclude that cellulose is essential for encystation and that cellulose synthase may be a suitable target for drugs to prevent encystation and render amoeba pathogens susceptible to conventional antibiotics.</p
The politics and economics of regulatory impact assessment
No full textThis is the author accepted manuscript. The final version is available from the publisher via the link in this record
Phase Distribution Efficiency of cm-Scale Ultrasonically Powered Receivers
No full textIn the domain of ultrasonically powered biomedical implants, there is an increasing interest in cm-scale ultrasonic receivers (RX). However, when a single-element transducer is used as the RX transducer, an uneven phase distribution across the RX area can significantly reduce the harvestable power. In this paper, we investigate the impact of lateral and angular misalignment on the acoustic field phase distribution across the RX surface. We show that, for a single-element RX transducer, lateral misalignment has minimal effect on the harvestable power, whereas even small angular misalignments can cause a considerable reduction, especially for larger RX sizes. We present a potential solution that consists of subdividing a large RX transducer (e.g. 20 × 20mm2) into smaller elements, which significantly improves power transfer efficiency by taking advantage of the smaller phase variation across the surface of each element. The trade-offs between achieving a minimum acceptable power transfer efficiency and managing the increased complexity in packaging and matching circuitry are also discussed.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic Components, Technology and MaterialsBio-Electronic
Highly efficient laser-driven Compton gamma-ray source
No full textThe recent advancement of high-intensity lasers has made all-optical Compton scattering become a promising way to produce ultrashort brilliant gamma-rays in an ultra-compact system. However, so far achieved Compton gamma-ray sources are limited by low conversion efficiency and spectral intensity. Here we present a highly efficient gamma photon emitter obtained by irradiating a high-intensity laser pulse on a miniature plasma device consisting of a plasma lens and a plasma mirror. This concept exploits strong spatiotemporal laser-shaping process and high-charge electron acceleration process in the plasma lens, as well as an efficient nonlinear Compton scattering process enabled by the plasma mirror. Our full three-dimensional particle-in-cell simulations demonstrate that in this novel scheme, brilliant gamma-rays with very high conversion efficiency (higher than 10(-2)) and spectral intensity (similar to 10(9) photons/0.1%BW) can be achieved by employing currently available petawatt-class lasers with intensity of 10(21) W cm(-2). Such efficient and intense gamma-ray sources would find applications in wide-ranging areas. ©2019 The Author(s)
Biomechanical analysis of sitting down and rising up from a chair with respect to the cruciate ligament forces
No full textCM Periods, CM Regulators, and Hypergeometric Functions, I
No full textWe prove the Gross-Deligne conjecture on CM periods for motives associated with H-2 of certain surfaces fibered over the projective line. Then we prove for the same motives a formula which expresses the K-1-regulators in terms of hypergeometric functions F-3(2), and obtain a new example of non-trivial regulators
Topographical attributes to predict soil hydraulic properties along a hillslope transect
No full textBasic soil properties have long been used to predict unsaturated soil hydraulic properties
with pedotransfer function (PTFs). Implementation of such PTFs is usually not feasible for
catchment-scale studies because of the experimental effort that would be required. On the
other hand, topographical attributes are often readily available. This study therefore
examines how well PTFs perform that use both basic soil properties and topographical
attributes for a hillslope in Basilicata, Italy. Basic soil properties and hydraulic data were
determined on soil samples taken at 50-m intervals along a 5-km hillslope transect.
Topographical attributes were determined from a digital elevation model. Spearman
coefficients showed that elevation (z) was positively correlated with organic carbon (OC)
and silt contents (0.62 and 0.59, respectively) and negatively with bulk density (rb) and sand
fraction (0.34 and 0.37). Retention parameters were somewhat correlated with
topographical attributes z, slope (b), aspect (cosf), and potential solar radiation. Water
contents were correlated most strongly with elevation (coefficient between 0.38 and 0.48)
and aspect during ‘‘wet’’ conditions. Artificial neural networks (ANNs) were developed for
21 different sets of predictors to estimate retention parameters, saturated hydraulic
conductivity (Ks), and water contents at capillary heads h = 50 cm and 12 bar (103 cm). The
prediction of retention parameters could be improved with 10% by including topography
(RMSE = 0.0327 cm3 cm3) using textural fractions, rb, OC, z, and b as predictors.
Furthermore, OC became a better predictor when the PTF also used z as predictor. The water
content at h = 50 cm could be predicted 26% more accurately (RMSE = 0.0231 cm3cm3)
using texture, rb, OC, z, b, and potential solar radiation as input. Predictions of ANNs
with and without topographical attributes were most accurate in the wet range (0 < h <
250 cm). Semivariograms of the hydraulic parameters and their residuals showed that the
ANNs could explain part of the (spatial) variability. The results of this study confirm the
utility of topographical attributes such as z, b, cosf, and potential solar radiation as predictors
for PTFs when basic soil properties are available. A next step would be the use of
topographical attributes when no or limited other predictors are available
Mapping SNOMED CT to ICD-10-CM
No full textA SNOMED CT-encoded problem list is required to satisfy the Certification Criteria for Stage 2 “Meaningful Use”. ICD-10-CM has replaced ICD-9-CM as the reimbursement code set in 2015. Having a cross-map from SNOMED CT to ICD-10-CM would promote the use of SNOMED CT as the primary problem list terminology, while easing the transition to ICD-10-CM. There is no established principle and methodology on systematically and semantically linking SNOMED CT to ICD-10-CM. This research project describes the development of mapping principle, mapping guidelines, mapping tools and mapping methodology for a rule-based crosswalk to support semi-automatic generation of ICD-10-CM codes from SNOMED CT-encoded data. A series of mapping guidelines were developed based on the clinical use case, SNOMED CT modeling convention, and ICD-10-CM classification guidelines. One of the important methodology in developing the map set is using triangulation in generating legacy maps. Using the SNOMED CT to ICD-9-CM map and General Equivalence Mappings sequentially, Indirect Map was generated from SNOMED CT to ICD-10-CM for 96.2% of the SNOMED CT concepts within the scope of the study. Another innovation in this crossmapping research is implementation of a principle to handle age specification. The age rule was one type of rule to handle cases in which one SNOMED CT concept can map to different ICD-10-CM codes depending on the age of the patient. The age rule quality assurance (QA) was a mechanism to capture the age specification that can be easily missed by manual mapping. The results showed that the mapping guidelines ensured the mapping consistency, which potentially would reduce the mapping discrepancy between the two independent parallel mapping efforts. It also made it possible that the map set can be used in a meaningful way when data is exchanged. On this triangulation method in generating legacy map, an Indirect Map generated from SNOMED CT to ICD-10-CM covered a very high percentage of SNOMED CT concepts. Overall, this Indirect Map had a moderate degree of agreement with the Direct SNOMED CT to ICD-10-CM map. However, the indirect synonymy maps have much higher precision and can be used for quality assurance (QA) of the three maps. The age rule QA identified 342 out of 7,277 concepts which potentially required age rules, among these 50.3% turned out to be true positives. Without this QA, a large proportion of age rules in the published Map would have been missed. The outcomes of this research project include a set of mapping principle, mapping guidelines, mapping tools and mapping methodology for a rule-based crosswalk from SNOMED CT to ICD-10-CM. All these could be used as a prototype in other cross standard mappings. For example, in the US, ICD-10-PCS officially replaced ICD-9-CM from October 2015 onwards. A project was formulating earlier this year (2015) for the purpose of creating the map from SNOMED CT procedure to ICD-10-PCS. It is a pleasant finding that tooling, principles and guidelines established in SNOMED CT to ICD-10-CM mapping can be re-used, with modifications, for the PCS mapping process.Ph.D.Includes bibliographical referencesby Junchuan X
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