530 research outputs found
Stuttering equivalence is too slow!
Groote and Wijs recently described an algorithm for deciding stuttering
equivalence and branching bisimulation equivalence, acclaimed to run in
time. Unfortunately, the algorithm does not always meet
the acclaimed running time. In this paper, we present two counterexamples where
the algorithms uses time. A third example shows that the
correction is not trivial. In order to analyse the problem we present
pseudocode of the algorithm, and indicate the time that can be spent on each
part of the algorithm in order to meet the desired bound. We also propose fixes
to the algorithm such that it indeed runs in time.Comment: 11 page
Editorialâdata analysis in metabolomics
Item does not contain fulltext2 p
The cytocompatibility and early osteogenic characteristics of an injectable calcium phosphate cement.
In this study, the cytocompatibility and early osteogenic characteristics of rat bone marrow cells
(RBMCs) on injectable calcium phosphate (CaP) cement (Calcibon) were investigated. In addition to
unmodified CaP cement discs, 2 other treatments were given to the discs: preincubation in MilliQ and
sintering at different temperatures. After primary culture, RBMCs were dropwise seeded on the discs
and cultured for 12 days. The samples were evaluated in terms of cell viability, morphology (live and dead
assays and scanning electron microscopy (SEM)), cell proliferation (deoxyribonucleic acid (DNA) analyses),
early cell differentiation (alkaline phosphatase (ALP) activity), and physicochemical analyses (xray
diffraction (XRD)). The live and dead, DNA, and SEM results showed that Calcibon discs without
any additional treatment were not supporting osteoblast-like cells in vitro. There were fewer cells, and
cell layers were detached from the disc surface. Therefore, different preincubation periods and sintering
temperatures were evaluated to improve the cytocompatibility of the CaP cement. Preincubating discs in
MilliQ for periods of 1, 4, 8, and 12 weeks resulted in the hydrolysis of a-tri calcium phosphate (TCP)
into an apatite-like structure with some b-TCP, as shown with XRD, but the material was not cytocompatible.
Sintering the discs between 8008C and 11008C resulted in conversion of a-TCP to b-TCP
with some hydroxyapatite and an increase in crystallinity. Eventually, the discs sintered at 11008C
achieved better cell attachment, more-abundant cell proliferation, and earlier differentiation than other
sintered (6008C, 8008C, and 10008C), preincubated, and unmodified specimens. On basis of our results,
we conclude that in vivo results with CaP-based cements do not guarantee in vitro applicability. Furthermore,
unmodified Calcibon is not cytocompatible in vitro, although preincubation of the material
results in a more-favorable cell response, sintering of the material at 11008C results in the best osteogenic
properties. In contrast to in vivo studies, the Calcibon CaP cement is not suitable as a scaffold for cellbased
tissue-engineering strategies
Mono/Multi-material Characterization Using Hyperspectral Images and Multi-Block Non-Negative Matrix Factorization
Plastic sorting is a very essential step in waste management, especially due
to the presence of multilayer plastics. These monomaterial and multimaterial
plastics are widely employed to enhance the functional properties of packaging,
combining beneficial properties in thickness, mechanical strength, and heat
tolerance. However, materials containing multiple polymer species need to be
pretreated before they can be recycled as monomaterials and therefore should
not end up in monomaterial streams. Industry 4.0 has significantly improved
materials sorting of plastic packaging in speed and accuracy compared to manual
sorting, specifically through Near Infrared Hyperspectral Imaging (NIRHSI) that
provides an automated, fast, and accurate material characterization, without
sample preparation. Identification of multimaterials with HSI however requires
novel dedicated approaches for chemical pattern recognition. Non negative
Matrix Factorization, NMF, is widely used for the chemical resolution of
hyperspectral images. Chemically relevant model constraints may make it
specifically valuable to identify multilayer plastics through HSI.
Specifically, Multi Block Non Negative Matrix Factorization (MBNMF) with
correspondence among different chemical species constraint may be used to
evaluate the presence or absence of particular polymer species. To translate
the MBNMF model into an evidence based sorting decision, we extended the model
with an F test to distinguish between monomaterial and multimaterial objects.
The benefits of our new approach, MBNMF, were illustrated by the identification
of several plastic waste objects
Systematic reduction of Hyperspectral Images for high-throughput Plastic Characterization
Hyperspectral Imaging (HSI) combines microscopy and spectroscopy to assess
the spatial distribution of spectroscopically active compounds in objects, and
has diverse applications in food quality control, pharmaceutical processes, and
waste sorting. However, due to the large size of HSI datasets, it can be
challenging to analyze and store them within a reasonable digital
infrastructure, especially in waste sorting where speed and data storage
resources are limited. Additionally, as with most spectroscopic data, there is
significant redundancy, making pixel and variable selection crucial for
retaining chemical information. Recent high-tech developments in chemometrics
enable automated and evidence-based data reduction, which can substantially
enhance the speed and performance of Non-Negative Matrix Factorization (NMF), a
widely used algorithm for chemical resolution of HSI data. By recovering the
pure contribution maps and spectral profiles of distributed compounds, NMF can
provide evidence-based sorting decisions for efficient waste management. To
improve the quality and efficiency of data analysis on hyperspectral imaging
(HSI) data, we apply a convex-hull method to select essential pixels and
wavelengths and remove uninformative and redundant information. This process
minimizes computational strain and effectively eliminates highly mixed pixels.
By reducing data redundancy, data investigation and analysis become more
straightforward, as demonstrated in both simulated and real HSI data for
plastic sorting
Bone regenerative properties of injectable PGLA-CaP composite with TGF-beta1 in a rat augmentation model.
The aim of this study was to examine the bone augmentation properties of an injectable composite
consisting of PLGA microspheres/CaP cement (20/80), and the additional effect of loading
PLGA microspheres with TGF-ÎČ1 (200 ng). For this purpose, PLGA/CaP composites (control) and
PLGA/CaP composites loaded with TGF-ÎČ1 (test group) were injected on top of the skulls of 24
Wistar rats. Each rat received 2 materials from the same experimental group, and in total 48
implants were placed (n = 8). After 2, 4, and 8 weeks the results were evaluated histologically
and histomorphometrically. The contact length between the implants and newly formed bone
increased in time, and was significantly higher for the TGF-ÎČ1-loaded composites after 2 weeks.
Also, bone formation was significantly higher for the TGF-ÎČ1-loaded composites (18.5% ± 3)
compared to controls (7.21% ± 5) after 8 weeks of implantation. Immunohistochemical staining
demonstrated massive inflammatory infiltrates in both groups, particularly at 2 weeks, which
decreased substantially at 4 and 8 weeks. In conclusion, injectable PLGA/CaP composites stimulated
bone augmentation in a rat model. The addition of TGF-ÎČ1 to the composite significantly increased
bone contact at 2 weeks and enhanced new bone formation at 8 weeks
An experimental study on the effects of a simulation game on studentsâ clinical cognitive skills and motivation
Simulation games are becoming increasingly popular in education, but more insight in their critical design features is needed. This study investigated the effects of fidelity of open patient cases in adjunct to an instructional e-module on studentsâ cognitive skills and motivation. We set up a three-group randomized post-test-only design: a control group working on an e-module; a cases group, combining the e-module with low-fidelity text-based patient cases, and a game group, combining the e-module with a high-fidelity simulation game with the same cases. Participants completed questionnaires on cognitive load and motivation. After a 4-week study period, blinded assessors rated studentsâ cognitive emergency care skills in two mannequin-based scenarios. In total 61 students participated and were assessed; 16 control group students, 20 cases students and 25 game students. Learning time was 2 h longer for the cases and game groups than for the control group. Acquired cognitive skills did not differ between groups. The game group experienced higher intrinsic and germane cognitive load than the cases group (p = 0.03 and 0.01) and felt more engaged (p < 0.001). Students did not profit from working on open cases (in adjunct to an e-module), which nonetheless challenged them to study longer. The e-module appeared to be very effective, while the high-fidelity game, although engaging, probably distracted students and impeded learning. Medical educators designing motivating and effective skills training for novices should align case complexity and fidelity with studentsâ proficiency level. The relation between case-fidelity, motivation and skills development is an important field for further study
An experimental study on the effects of a simulation game on studentsâ clinical cognitive skills and motivation
textabstractSimulation games are becoming increasingly popular in education, but more insight in their critical design features is needed. This study investigated the effects of fidelity of open patient cases in adjunct to an instructional e-module on studentsâ cognitive skills and motivation. We set up a three-group randomized post-test-only design: a control group working on an e-module; a cases group, combining the e-module with low-fidelity text-based patient cases, and a game group, combining the e-module with a high-fidelity simulation game with the same cases. Participants completed questionnaires on cognitive load and motivation. After a 4-week study period, blinded assessors rated studentsâ cognitive emergency care skills in two mannequin-based scenarios. In total 61 students participated and were assessed; 16 control group students, 20 cases students and 25 game students. Learning time was 2 h longer for the cases and game groups than for the control group. Acquired cognitive skills did not differ between groups. The game group experienced higher intrinsic and germane cognitive load than the cases group (p = 0.03 and 0.01) and felt more engaged (p < 0.001). Students did not profit from working on open cases (in adjunct to an e-module), which nonetheless challenged them to study longer. The e-module appeared to be very effective, while the high-fidelity game, although engaging, probably distracted students and impeded learning. Medical educators designing motivating and effective skills training for novices should align case complexity and fidelity with studentsâ proficiency level. The relation between case-fidelity, motivation and skills development is an important field for further study
Investigation of the Domain Wall Fermion Approach to Chiral Gauge Theories on the Lattice
We investigate a recent proposal to construct chiral gauge theories on the
lattice using domain wall fermions. We restrict ourselves to the finite volume
case, in which two domain walls are present, with modes of opposite chirality
on each of them. We couple the chiral fermions on only one of the domain walls
to a gauge field. In order to preserve gauge invariance, we have to add a
scalar field, which gives rise to additional light mirror fermion and scalar
modes. We argue that in an anomaly free model these extra modes would decouple
if our model possesses a so-called strong coupling symmetric phase. However,
our numerical results indicate that such a phase most probably does not exist.
---- Note: 9 Postscript figures are appended as uuencoded compressed tar file.Comment: 27p. Latex; UCSD/PTH 93-28, Wash. U. HEP/93-6
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