339 research outputs found
Composite Liquid Marbles as a Macroscopic Model System Representing Shedding of Enveloped Viruses
Copyright © 2020 American Chemical Society. A model macroscopic system imitating the entry of viruses into living cells is suggested. The system represents the contact of a composite (core-shell) liquid marble with hydrophobic/hydrophilic particles. Composite liquid marbles are water droplets coated with silicone oil armored with nanometer-sized hydrophobic particles serving as an interfacial model of a living cell. Composite marbles absorbed hydrophilic polymer particles but prevented hydrophobic particles from entering their core. Swallowing of hydrophilic particles by composite marbles resembles the penetration of viruses into living cells. The interfacial mechanism of absorption is suggested
A Characterization of Scale Invariant Responses in Enzymatic Networks
An ubiquitous property of biological sensory systems is adaptation: a step
increase in stimulus triggers an initial change in a biochemical or
physiological response, followed by a more gradual relaxation toward a basal,
pre-stimulus level. Adaptation helps maintain essential variables within
acceptable bounds and allows organisms to readjust themselves to an optimum and
non-saturating sensitivity range when faced with a prolonged change in their
environment. Recently, it was shown theoretically and experimentally that many
adapting systems, both at the organism and single-cell level, enjoy a
remarkable additional feature: scale invariance, meaning that the initial,
transient behavior remains (approximately) the same even when the background
signal level is scaled. In this work, we set out to investigate under what
conditions a broadly used model of biochemical enzymatic networks will exhibit
scale-invariant behavior. An exhaustive computational study led us to discover
a new property of surprising simplicity and generality, uniform linearizations
with fast output (ULFO), whose validity we show is both necessary and
sufficient for scale invariance of enzymatic networks. Based on this study, we
go on to develop a mathematical explanation of how ULFO results in scale
invariance. Our work provides a surprisingly consistent, simple, and general
framework for understanding this phenomenon, and results in concrete
experimental predictions
Deep Archetypal Analysis
"Deep Archetypal Analysis" generates latent representations of
high-dimensional datasets in terms of fractions of intuitively understandable
basic entities called archetypes. The proposed method is an extension of linear
"Archetypal Analysis" (AA), an unsupervised method to represent multivariate
data points as sparse convex combinations of extremal elements of the dataset.
Unlike the original formulation of AA, "Deep AA" can also handle side
information and provides the ability for data-driven representation learning
which reduces the dependence on expert knowledge. Our method is motivated by
studies of evolutionary trade-offs in biology where archetypes are species
highly adapted to a single task. Along these lines, we demonstrate that "Deep
AA" also lends itself to the supervised exploration of chemical space, marking
a distinct starting point for de novo molecular design. In the unsupervised
setting we show how "Deep AA" is used on CelebA to identify archetypal faces.
These can then be superimposed in order to generate new faces which inherit
dominant traits of the archetypes they are based on.Comment: Published at the German Conference on Pattern Recognition 2019 (GCPR
Understanding constraint expressions in large conceptual schemas by automatic filtering
Human understanding of constraint expressions (also called schema rules) in large conceptual schemas is very di cult. This is due to the fact that the elements (entity types, attributes, relationship types) involved in an expression are de ned in di fferent places in the schema, which may be very distant from each other and embedded in an intricate web of irrelevant elements. The problem is insignifi cant when the
conceptual schema is small, but very signi cant when it is large. In this paper we describe a novel method that, given a set of constraint expressions and a large conceptual schema, automatically filters the conceptual schema, obtaining a smaller one that contains the elements of interest for
the understanding of the expressions. We also show the application of the method to the important case of understanding the specication of event types, whose constraint expressions consists of a set of pre and postconditions. We have evaluated the method by means of its application to a set of large conceptual schemas. The results show that the method is eff ective and e cient. We deal with conceptual schemas in UML/OCL,
but the method can be adapted to other languages.Peer ReviewedPreprin
Self-propulsion of water-supported liquid marbles filled with sulfuric acid
Self-propulsion of liquid marbles filled with sulfuric acid and coated with hydrophobic fluorosilica powder on a water surface is reported. The prolonged self-propulsion of marbles occurs over a couple of minutes with a typical velocity of the center of mass of the marble being . The shell of the marble is not uniform, resulting in the asymmetric absorption of water by a marble, giving rise to the nonuniform thermal field within its volume. The maximum temperature reached at the liquid marble surface was 70 °C. The self-propelled marble increased its mass by one-third during the course of its motion. The increase in mass followed by the marbles’ heating is due to the adsorption of water vapor by their surface, which is permeable to gases. This gives rise to an exothermic chemical reaction, which in turn gives rise to Marangoni thermo-capillary flow driving the marble. Thermo-physical analysis of the problem is presented. The role of soluto-capillary flow in self-propulsion is negligible
New Modularity of DAP-Kinases: Alternative Splicing of the DRP-1 Gene Produces a ZIPk-Like Isoform
DRP-1 and ZIPk are two members of the Death Associated Protein Ser/Thr Kinase
(DAP-kinase) family, which function in different settings of cell death
including autophagy. DAP kinases are very similar in their catalytic domains but
differ substantially in their extra-catalytic domains. This difference is
crucial for the significantly different modes of regulation and function among
DAP kinases. Here we report the identification of a novel alternatively spliced
kinase isoform of the DRP-1 gene, termed DRP-1β. The
alternative splicing event replaces the whole extra catalytic domain of DRP-1
with a single coding exon that is closely related to the sequence of the extra
catalytic domain of ZIPk. As a consequence, DRP-1β lacks the calmodulin
regulatory domain of DRP-1, and instead contains a leucine zipper-like motif
similar to the protein binding region of ZIPk. Several functional assays proved
that this new isoform retained the biochemical and cellular properties that are
common to DRP-1 and ZIPk, including myosin light chain phosphorylation, and
activation of membrane blebbing and autophagy. In addition, DRP-1β also
acquired binding to the ATF4 transcription factor, a feature characteristic of
ZIPk but not DRP-1. Thus, a splicing event of the DRP-1 produces a ZIPk like
isoform. DRP-1β is highly conserved in evolution, present in all known
vertebrate DRP-1 loci. We detected the corresponding mRNA and
protein in embryonic mouse brains and in human embryonic stem cells thus
confirming the in vivo utilization of this isoform. The
discovery of module conservation within the DAPk family members illustrates a
parsimonious way to increase the functional complexity within protein families.
It also provides crucial data for modeling the expansion and evolution of DAP
kinase proteins within vertebrates, suggesting that DRP-1 and ZIPk most likely
evolved from their ancient ancestor gene DAPk by two gene duplication events
that occurred close to the emergence of vertebrates
Serum amyloid A (SAA): a novel biomarker for uterine serous papillary cancer
BACKGROUND: Uterine serous papillary carcinoma (USPC) is a biologically aggressive variant of endometrial cancer. We investigated
the expression of Serum Amyloid A (SAA) and evaluated its potential as a serum biomarker in USPC patients.
METHODS: SAA gene and protein expression levels were evaluated in USPC and normal endometrial tissues (NEC) by real-time PCR,
immunohistochemistry (IHC), flow cytometry and by a sensitive bead-based immunoassay. SAA concentration in 123 serum samples
from 51 healthy women, 42 women with benign diseases, and 30 USPC patients were also studied.
RESULTS: SAA gene expression levels were significantly higher in USPC when compared with NEC (mean copy number by
RT\u2013PCR\ubc162 vs 2.21; P\ubc0.0002). IHC revealed diffuse cytoplasmic SAA protein staining in USPC tissues. High intracellular levels
of SAA were identified in primary USPC cell lines evaluated by flow cytometry and SAA was found to be actively secreted in vitro.
SAA concentrations (mgml 1) had a median (95% CIs) of 6.0 (4.0\u20138.9) in normal healthy females and 6.0 (4.2\u20138.1) in patients with
benign disease (P\ubc0.92). In contrast, SAA values in the serum of USPC patients had a median (95% CI) of 15.6 (9.2\u201356.2),
significantly higher than those in the healthy group (P\ubc0.0005) and benign group (P\ubc0.0006). Receiver operating characteristics
(ROC) analysis of serum SAA to classify advanced- and early-stage USPC yielded an area under the ROC curve of 0.837
(P\ubc0.0024).
CONCLUSION: SAA is not only a liver-secreted protein but is also a USPC cell product. SAA may represent a novel biomarker for
USPC to assist in staging patients preoperatively, and to monitor early-disease recurrence and response to therapy
Integration of DFDs into a UML - based model-driven engineering approach
The main aim of this article is to discuss how the functional and the object-oriented views can be inter-played to represent the various modeling perspectives of embedded systems.We discuss whether the object-oriented modeling paradigm, the predominant one to develop software at the present time, is also adequate for modeling embedded software and how it can be used with the functional paradigm.More specifically, we present how the main modeling tool of the traditional structured methods, data flow diagrams, can be integrated in an object-oriented development strategy based on the unified modeling language. The rationale behind the approach is that both views are important for modeling purposes in embedded systems environments, and thus a combined and integrated model is not only useful, but also fundamental for developing complex systems. The approach was integrated in amodel-driven engineering process, where tool support for the models used was provided. In addition, model transformations have been specified and implemented to automate the process.We exemplify the approach with an IPv6 router case study.FEDER -Fundação para a Ciência e a Tecnologia(HH-02-383
Smart Tourism Destinations: Can the Destination Management Organizations Exploit Benefits of the ICTs? Evidences from a Multiple Case Study
Recent developments of ICTs enable new ways to experience tourism and conducted to the concept of smart tourism. The adoption of cutting-edge technologies and its combination with innovative organizational models fosters cooperation, knowledge sharing, and open innovation among service providers in tourism destination. Moreover, it offers innovative services to visitors. In few words, they become smart tourism destinations. In this paper, we report first results of the SMARTCAL project aimed at conceiving a digital platform assisting Destination Management Organizations (DMOs) in providing smart tourism services. A DMO is the organization charged with managing the tourism offer of a collaborative network, made up of service providers acting in a destination. In this paper, we adopted a multiple case studies approach to analyze five Italian DMOs. Our aims were to investigate (1) if, and how, successful DMOs were able to offer smart tourism services to visitors; (2) if the ICTs adoption level was related to the collaboration level among DMO partners. First results highlighted that use of smart technologies was still in an embryonic stage of development, and it did not depend from collaboration levels
- …