48 research outputs found
Haptic Water; Haptics on an Animated Surface
Haptic rendering is becoming an important element of multimodal interaction. Often a real-time coupling between haptics and visualization is required, based upon an underlying physical model. In this paper, we study haptic rendering and visualization of the generation of waves in shallow water. For applications, it is usually more important to come up with a believable simulation, rather than a physically accurate simulation. Therefore our focus was on obtaining suitable simplifications of the Kas-Miller model, and incorporation into a multimodal environment, aiming at haptic rendering and real-time visualization of waves. The result has been implemented and tested using a Haptic Master device, produced by FCS Control Systems
How do pupils understand historical time?:Some evidence from England and the Netherlands
One of the key aims of the English history National Curriculum is to ensure that pupils, ‘know and understand the history of these islands as a coherent, chronological narrative’. Teaching chronology is also important in the Netherlands. In this article we describe the Dutch curriculum and discuss research currently being undertaken which may inform our teaching about the understanding of time
Fermi-surface topological phase transition and horizontal order-parameter nodes in CaFeAs under pressure
Iron-based compounds (IBS) display a surprising variety of superconducting
properties that seems to arise from the strong sensitivity of these systems to
tiny details of the lattice structure. In this respect, systems that become
superconducting under pressure, like CaFeAs, are of particular
interest. Here we report on the first directional point-contact
Andreev-reflection spectroscopy (PCARS) measurements on CaFeAs crystals
under quasi-hydrostatic pressure, and on the interpretation of the results
using a 3D model for Andreev reflection combined with ab-initio calculations of
the Fermi surface (within the density functional theory) and of the order
parameter symmetry (within a random-phase-approximation approach in a
ten-orbital model). The almost perfect agreement between PCARS results at
different pressures and theoretical predictions highlights the intimate
connection between the changes in the lattice structure, a topological
transition in the hole-like Fermi surface sheet, and the emergence on the same
sheet of an order parameter with a horizontal node line.Comment: 13 pages, 8 color figures. This is an author-created, un-copyedited
version of an article published in Scientific Reports. The published version
is available online, together with Supplementary Information, at
http://www.nature.com/articles/srep2639
Single Crystal Growth and Characterization of the Iron-Based Superconductor KFe2As2 Synthesized by KAs Flux Method
Centimeter sized platelet single crystals of KFe2As2 were grown using a
self-flux method. An encapsulation technique using commercial stainless steel
container allowed the stable crystal growth lasting for more than 2 weeks.
Ternary K-Fe-As systems with various starting compositions were examined to
determine the optimal growth conditions. Employment of KAs flux led to the
growth of large single crystals with the typical size of as large as 15 mm x 10
mm x 0.4 mm. The grown crystals exhibit sharp superconducting transition at 3.4
K with the transition width 0.2 K, as well as the very large residual
resistivity ratio exceeding 450, evidencing the good sample quality.Comment: 4 pages, 6 Postscript figure
Quasi-one-dimensional antiferromagnetism and multiferroicity in CuCrO
The bulk magnetic properties of the new quasi-one-dimensional Heisenberg
antiferromagnet, CuCrO, were characterized by magnetic susceptibility, heat
capacity, optical spectroscopy, EPR and dielectric capacitance measurements and
density functional evaluations of the intra- and interchain spin exchange
interactions. We found type-II multiferroicity below the N\'{e}el temperature
of 8.2(5) K, arising from competing antiferromagnetic nearest-neighbor () and next-nearest-neighbor () intra-chain spin exchange
interactions. Experimental and theoretical results indicate that the ratio
is close to 2, putting CuCrO in the vicinity of
the Majumdar-Ghosh point.Comment: 9 pages, 8 figures, submitted to PR
Full-length human placental sFlt-1-e15a isoform induces distinct maternal phenotypes of preeclampsia in mice
<div><p>Objective</p><p>Most anti-angiogenic preeclampsia models in rodents utilized the overexpression of a truncated soluble fms-like tyrosine kinase-1 (sFlt-1) not expressed in any species. Other limitations of mouse preeclampsia models included stressful blood pressure measurements and the lack of postpartum monitoring. We aimed to 1) develop a mouse model of preeclampsia by administering the most abundant human placental sFlt-1 isoform (hsFlt-1-e15a) in preeclampsia; 2) determine blood pressures in non-stressed conditions; and 3) develop a survival surgery that enables the collection of fetuses and placentas and postpartum (PP) monitoring.</p><p>Methods</p><p>Pregnancy status of CD-1 mice was evaluated with high-frequency ultrasound on gestational days (GD) 6 and 7. Telemetry catheters were implanted in the carotid artery on GD7, and their positions were verified by ultrasound on GD13. Mice were injected through tail-vein with adenoviruses expressing hsFlt-1-e15a (n = 11) or green fluorescent protein (GFP; n = 9) on GD8/GD11. Placentas and pups were delivered by cesarean section on GD18 allowing PP monitoring. Urine samples were collected with cystocentesis on GD6/GD7, GD13, GD18, and PPD8, and albumin/creatinine ratios were determined. GFP and hsFlt-1-e15a expression profiles were determined by qRT-PCR. Aortic ring assays were performed to assess the effect of hsFlt-1-e15a on endothelia.</p><p>Results</p><p>Ultrasound predicted pregnancy on GD7 in 97% of cases. Cesarean section survival rate was 100%. Mean arterial blood pressure was higher in hsFlt-1-e15a-treated than in GFP-treated mice (∆MAP = 13.2 mmHg, p = 0.00107; GD18). Focal glomerular changes were found in hsFlt-1-e15a -treated mice, which had higher urine albumin/creatinine ratios than controls (109.3±51.7μg/mg vs. 19.3±5.6μg/mg, p = 4.4x10<sup>-2</sup>; GD18). Aortic ring assays showed a 46% lesser microvessel outgrowth in hsFlt-1-e15a-treated than in GFP-treated mice (p = 1.2x10<sup>-2</sup>). Placental and fetal weights did not differ between the groups. One mouse with liver disease developed early-onset preeclampsia-like symptoms with intrauterine growth restriction (IUGR).</p><p>Conclusions</p><p>A mouse model of late-onset preeclampsia was developed with the overexpression of hsFlt-1-e15a, verifying the <i>in vivo</i> pathologic effects of this primate-specific, predominant placental sFlt-1 isoform. HsFlt-1-e15a induced early-onset preeclampsia-like symptoms associated with IUGR in a mouse with a liver disease. Our findings support that hsFlt-1-e15a is central to the terminal pathway of preeclampsia, and it can induce the full spectrum of symptoms in this obstetrical syndrome.</p></div
TOL PLASMID-SPECIFIED XYLENE OXYGENASE IS A WIDE SUBSTRATE RANGE MONOOXYGENASE CAPABLE OF OLEFIN EPOXIDATION
Xylene oxygenase, which is encoded on the TOL plasmid pWWO of Pseudomonas putida mt-2, is a key enzyme system in the degradation of toluene and xylenes by this organism. It was expressed in an Escherichia coli recombinant strain carrying the xy1MA structural genes. This recombinant, which expressed xylene oxygenase from the heat-shock induced lambda P-L promoter, was analyzed for its potential as a biocatalytic tool so as to effect the oxidation of side chains of aromatic hydrocarbons to the corresponding alcohols. Compounds that were tested as potential substrates carried different substituents on the aromatic ring at ortho, meta, and para positions, relative to the methyl moiety. Products that accumulated after administration of the aromatic hydrocarbons to concentrated suspensions of the recombinant were identified by gas chomatography and mass spectrometry. Toluene derivatives with ortho substituents could not serve as substrates for the biocatalyst, whereas a number of meta- or parasubstituted analogs were efficiently oxidized to the corresponding benzylalcohols. Bioconversion of the substrates by resting cells varied from 3 mu mol min(-1) g(-1) cell dry weight for 1,3,5-trimethylbenzene to 18 mu mol min(-1) g(-1) cell dry weight for meta-xylene. Whole cells that expressed xylene oxygenase did catalyze the oxidation of the methyl substituent attached to a benzene ring, but no conversion of n-alkylbenzene derivatives with longer side chains was observed. Although the ethyl group of ethylbenzene could not be converted by the biocatalyst, cells containing xylene oxygenase were capable of oxidizing the ethylene side group of styrene to produce styrene epoxide
TOL PLASMID-SPECIFIED XYLENE OXYGENASE IS A WIDE SUBSTRATE RANGE MONOOXYGENASE CAPABLE OF OLEFIN EPOXIDATION
Xylene oxygenase, which is encoded on the TOL plasmid pWWO of Pseudomonas putida mt-2, is a key enzyme system in the degradation of toluene and xylenes by this organism. It was expressed in an Escherichia coli recombinant strain carrying the xy1MA structural genes. This recombinant, which expressed xylene oxygenase from the heat-shock induced lambda P-L promoter, was analyzed for its potential as a biocatalytic tool so as to effect the oxidation of side chains of aromatic hydrocarbons to the corresponding alcohols. Compounds that were tested as potential substrates carried different substituents on the aromatic ring at ortho, meta, and para positions, relative to the methyl moiety. Products that accumulated after administration of the aromatic hydrocarbons to concentrated suspensions of the recombinant were identified by gas chomatography and mass spectrometry. Toluene derivatives with ortho substituents could not serve as substrates for the biocatalyst, whereas a number of meta- or parasubstituted analogs were efficiently oxidized to the corresponding benzylalcohols. Bioconversion of the substrates by resting cells varied from 3 mu mol min(-1) g(-1) cell dry weight for 1,3,5-trimethylbenzene to 18 mu mol min(-1) g(-1) cell dry weight for meta-xylene. Whole cells that expressed xylene oxygenase did catalyze the oxidation of the methyl substituent attached to a benzene ring, but no conversion of n-alkylbenzene derivatives with longer side chains was observed. Although the ethyl group of ethylbenzene could not be converted by the biocatalyst, cells containing xylene oxygenase were capable of oxidizing the ethylene side group of styrene to produce styrene epoxide
TOL PLASMID-SPECIFIED XYLENE OXYGENASE IS A WIDE SUBSTRATE RANGE MONOOXYGENASE CAPABLE OF OLEFIN EPOXIDATION
Xylene oxygenase, which is encoded on the TOL plasmid pWWO of Pseudomonas putida mt-2, is a key enzyme system in the degradation of toluene and xylenes by this organism. It was expressed in an Escherichia coli recombinant strain carrying the xy1MA structural genes. This recombinant, which expressed xylene oxygenase from the heat-shock induced lambda P-L promoter, was analyzed for its potential as a biocatalytic tool so as to effect the oxidation of side chains of aromatic hydrocarbons to the corresponding alcohols. Compounds that were tested as potential substrates carried different substituents on the aromatic ring at ortho, meta, and para positions, relative to the methyl moiety. Products that accumulated after administration of the aromatic hydrocarbons to concentrated suspensions of the recombinant were identified by gas chomatography and mass spectrometry. Toluene derivatives with ortho substituents could not serve as substrates for the biocatalyst, whereas a number of meta- or parasubstituted analogs were efficiently oxidized to the corresponding benzylalcohols. Bioconversion of the substrates by resting cells varied from 3 mu mol min(-1) g(-1) cell dry weight for 1,3,5-trimethylbenzene to 18 mu mol min(-1) g(-1) cell dry weight for meta-xylene. Whole cells that expressed xylene oxygenase did catalyze the oxidation of the methyl substituent attached to a benzene ring, but no conversion of n-alkylbenzene derivatives with longer side chains was observed. Although the ethyl group of ethylbenzene could not be converted by the biocatalyst, cells containing xylene oxygenase were capable of oxidizing the ethylene side group of styrene to produce styrene epoxide