77 research outputs found
Offline-verifiable Data from Distributed Ledger-based Registries
Trust management systems often use registries to authenticate data, or form
trust decisions. Examples are revocation registries and trust status lists. By
introducing distributed ledgers (DLs), it is also possible to create
decentralized registries. A verifier then queries a node of the respective
ledger, e.g., to retrieve trust status information during the verification of a
credential. While this ensures trustworthy information, the process requires
the verifier to be online and the ledger node available. Additionally, the
connection from the verifier to the registry poses a privacy issue, as it leaks
information about the user's behavior.
In this paper, we resolve these issues by extending existing ledger APIs to
support results that are trustworthy even in an offline setting. We do this by
introducing attestations of the ledger's state, issued by ledger nodes,
aggregatable into a collective attestation by all nodes. This attestation
enables a user to prove the provenance of DL-based data to an offline verifier.
Our approach is generic. So once deployed it serves as a basis for any use case
with an offline verifier. We also provide an implementation for the Ethereum
stack and evaluate it, demonstrating the practicability of our approach.Comment: This is the full version of a paper which was presented at the 19th
International Conference on Security and Cryptography (SECRYPT '22
Multidimensional Study on Users’ Evaluation of the KRAKEN Personal Data Sharing Platform
Background: Recent advances in the design of blockchain-based personal data sharing platforms bring the benefit of empowering users with more control and privacy-preserving measures in sharing data products. However, so far very little is known about users’ intentions to adopt such platforms for providing or consuming data products. Objective: This study aims to investigate users’ main expectations, preferences, and concerns regarding the adoption of blockchain-based personal data sharing platforms in the health and education domains. Methods: Fifteen participants were involved in a multidimensional evaluation of a prototyped release of the KRAKEN blockchain-based data sharing platform and asked to assess it in the health or education pilot domains. Data collected during online group interviews with participants were analyzed by applying the micro interlocutor technique to provide a descriptive overview of participant responses. Results: Participants showed a marginal acceptance of the prototype usability, asking for some improvements of the user experience and for a more transparent presentation of the platform security and privacy preserving capabilities. Participants expressed interest in using the platform as data providers and consumers as well as setting privacy policies for sharing data products with third parties, including the possibility of revoking access to data. Conclusions: Blockchain-based data sharing platforms are more likely to engage target users when technical design is informed by a deeper knowledge of their needs, expectations, and relevant concerns
Influence of Inner Shell Structure on the Encapsulation Behavior of Dexamethasone and Tacrolimus
We here present the synthesis and characterization of a set of biodegradable
core–multishell (CMS) nanocarriers. The CMS nanocarrier structure consists of
hyperbranched polyglycerol (hPG) as core material, a hydrophobic (12, 15, 18,
19, and 36 C-atoms) inner and a polyethylene glycol monomethyl ether (mPEG)
outer shell that were conjugated by ester bonds only to reduce the toxicity of
metabolites. The loading capacities (LC) of the drugs, dexamethasone and
tacrolimus, and the aggregate formation, phase transitions, and degradation
kinetics were determined. The intermediate inner shell length (C15) system had
the best overall performance with good LCs for both drugs as well as a
promising degradation and release kinetics, which are of interest for dermal
deliver
Floral scent evolution in the genus jaborosa (Solanaceae): Influence of ecological and environmental factors
Floral scent is a key communication channel between plants and pollinators. However,the contributions of environment and phylogeny to floral scent composition remain poorly understood. In this study, we characterized interspecific variation of floral scent composition in the genus Jaborosa Juss. (Solanaceae) and, using an ecological niche modelling approach (ENM), we assessed the environmental variables that exerted the strongest influence on floral scent variation, taking into account pollination mode and phylogenetic relationships. Our results indicate that two major evolutionary themes have emerged: (i) a ?warm Lowland Subtropical nectar-rewarding clade? with large white hawkmoth pollinated flowers that emit fragrances dominated by oxygenated aromatic or sesquiterpenoid volatiles, and (ii) a ?cool-temperate brood-deceptive clade? of largely fly-pollinated species found at high altitudes (Andes) or latitudes (Patagonian Steppe) that emit foul odors including cresol, indole and sulfuric volatiles. The joint consideration of floral scent profiles, pollination mode, and geoclimatic context helped us to disentangle the factors that shaped floral scent evolution across ?pollinator climates? (geographic differences in pollinator abundance or preference). Our findings suggest that the ability of plants in the genus Jaborosa to colonize newly formed habitats during Andean orogeny was associated with striking transitions in flower scent composition that trigger specific odor-driven behaviors in nocturnal hawkmoths and saprophilous fly pollinators.Fil: More, Marcela. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de BiologÃa Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas FÃsicas y Naturales. Instituto Multidisciplinario de BiologÃa Vegetal; ArgentinaFil: Soteras, MarÃa Florencia. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de BiologÃa Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas FÃsicas y Naturales. Instituto Multidisciplinario de BiologÃa Vegetal; ArgentinaFil: Ibañez, Ana Clara. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de BiologÃa Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas FÃsicas y Naturales. Instituto Multidisciplinario de BiologÃa Vegetal; ArgentinaFil: Dötterl, Stefan. Paris-lodron-university Of Salzburg; AustriaFil: Cocucci, Andrea Aristides. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de BiologÃa Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas FÃsicas y Naturales. Instituto Multidisciplinario de BiologÃa Vegetal; ArgentinaFil: Raguso, Robert A.. Cornell University, Dept. Of Neurobiology And Behavior; Estados Unido
The overdensity and masses of the friends-of-friends halos and universality of the halo mass function
The friends-of-friends algorithm (hereafter, FOF) is a percolation algorithm
which is routinely used to identify dark matter halos from N-body simulations.
We use results from percolation theory to show that the boundary of FOF halos
does not correspond to a single density threshold but to a range of densities
close to a critical value that depends upon the linking length parameter, b. We
show that for the commonly used choice of b = 0.2, this critical density is
equal to 81.62 times the mean matter density. Consequently, halos identified by
the FOF algorithm enclose an average overdensity which depends on their density
profile (concentration) and therefore changes with halo mass contrary to the
popular belief that the average overdensity is ~180. We derive an analytical
expression for the overdensity as a function of the linking length parameter b
and the concentration of the halo. Results of tests carried out using simulated
and actual FOF halos identified in cosmological simulations show excellent
agreement with our analytical prediction. We also find that the mass of the
halo that the FOF algorithm selects crucially depends upon mass resolution. We
find a percolation theory motivated formula that is able to accurately correct
for the dependence on number of particles for the mock realizations of
spherical and triaxial Navarro-Frenk-White halos. However, we show that this
correction breaks down when applied to the real cosmological FOF halos due to
presence of substructures. Given that abundance of substructure depends on
redshift and cosmology, we expect that the resolution effects due to
substructure on the FOF mass and halo mass function will also depend on
redshift and cosmology and will be difficult to correct for in general.
Finally, we discuss the implications of our results for the universality of the
mass function.Comment: 19 pages, 17 figures, submitted to ApJ supplemen
Lipid droplet degradation by autophagy connects mitochondria metabolism to Prox1-driven expression of lymphatic genes and lymphangiogenesis.
Autophagy has vasculoprotective roles, but whether and how it regulates lymphatic endothelial cells (LEC) homeostasis and lymphangiogenesis is unknown. Here, we show that genetic deficiency of autophagy in LEC impairs responses to VEGF-C and injury-driven corneal lymphangiogenesis. Autophagy loss in LEC compromises the expression of main effectors of LEC identity, like VEGFR3, affects mitochondrial dynamics and causes an accumulation of lipid droplets (LDs) in vitro and in vivo. When lipophagy is impaired, mitochondrial ATP production, fatty acid oxidation, acetyl-CoA/CoA ratio and expression of lymphangiogenic PROX1 target genes are dwindled. Enforcing mitochondria fusion by silencing dynamin-related-protein 1 (DRP1) in autophagy-deficient LEC fails to restore LDs turnover and lymphatic gene expression, whereas supplementing the fatty acid precursor acetate rescues VEGFR3 levels and signaling, and lymphangiogenesis in LEC-Atg5-/- mice. Our findings reveal that lipophagy in LEC by supporting FAO, preserves a mitochondrial-PROX1 gene expression circuit that safeguards LEC responsiveness to lymphangiogenic mediators and lymphangiogenesis.We thank K. Rillaerts, J. Souffreau, and A. Bouche, for expert technical support and Dr. A. Luttun and Dr. A. Zijsen for sharing tools and advices. P.A. is supported by grants from the Flemish Research Foundation (FWO-Vlaanderen; G076617N, G049817N, G070115N), the EOS MetaNiche consortium N degrees 40007532, Stichting tegen Kanker (FAF-F/2018/1252) and the iBOF/21/053 ATLANTIS consortium with G.B. D.H. is the recipient of an FWO Doctoral Fellowship from the Flemish Research Foundation (FWO-Vlaanderen, 1186019N), Belgium. M.B. is supported by the `Fonds voor Wetenschappelijk Onderzoek' (FWO). K.J. is the recipient of an FWO Postdoctoral Fellowship from the Flemish Research Foundation (FWO-Vlaanderen). P.C. is supported by Methusalem funding by the Flemish government, and by an ERC Advanced Research Grant (EU-ERC269073).S
The dark matter assembly of the Local Group in constrained cosmological simulations of a LambdaCDM universe
We make detailed theoretical predictions for the assembly properties of the
Local Group (LG) in the standard LambdaCDM cosmological model. We use three
cosmological N-body dark matter simulations from the CLUES project, which are
designed to reproduce the main dynamical features of the matter distribution
down to the scale of a few Mpc around the LG. Additionally, we use the results
of an unconstrained simulation with a sixty times larger volume to calibrate
the influence of cosmic variance. We characterize the Mass Aggregation History
(MAH) for each halo by three characteristic times, the formation, assembly and
last major merger times. A major merger is defined by a minimal mass ratio of
10:1. We find that the three LGs share a similar MAH with formation and last
major merger epochs placed on average \approx 10 - 12 Gyr ago. Between 12% and
17% of the halos in the mass range 5 x 10^11 Msol/h < M_h < 5 x 10^12 Msol/h
have a similar MAH. In a set of pairs of halos within the same mass range, a
fraction of 1% to 3% share similar formation properties as both halos in the
simulated LG. An unsolved question posed by our results is the dynamical origin
of the MAH of the LGs. The isolation criteria commonly used to define LG-like
halos in unconstrained simulations do not narrow down the halo population into
a set with quiet MAHs, nor does a further constraint to reside in a low density
environment. The quiet MAH of the LGs provides a favorable environment for the
formation of disk galaxies like the Milky Way and M31. The timing for the
beginning of the last major merger in the Milky Way dark matter halo matches
with the gas rich merger origin for the thick component in the galactic disk.
Our results support the view that the specific large and mid scale environment
around the Local Group play a critical role in shaping its MAH and hence its
baryonic structure at present.Comment: 11 pages, 4 figures. Accepted for publication in MNRA
The Stereodivergent Formation of 2,6-cis and 2,6-trans-Tetrahydropyrans: Experimental and Computational Investigation of the Mechanism of a Thioester Oxy-Michael Cyclization
The origins of the stereodivergence in the thioester oxy-Michael cyclization for the formation of 4-hydroxy-2,6-cis- or 2,6-trans-substituted tetrahydropyran rings under different conditions was investigated both computationally and experimentally. Synthetic studies showed that the 4-hydroxyl group was essential for stereodivergence. When the 4-hydroxyl group was present, TBAF-mediated conditions gave the 2,6-trans-tetrahydropyran and trifluoroacetic acid-mediated conditions gave the 2,6-cis-tetrahydropyran. This stereodivergence vanished when the hydroxyl group was removed or protected. Computational studies revealed that: (i) the trifluoroacetic acid catalysed formation of 2,6-cis-tetrahydropyrans was mediated by a trifluoroacetate-hydroxonium bridge and proceeded via a chair-like transition state; (ii) the TBAF-mediated formation of 2,6-trans-tetrahydropyrans proceeded via a boat-like transition state, where the 4-hydroxyl group formed a crucial hydrogen bond to the cyclizing alkoxide; (iii) both reactions are under kinetic control. The utility of this stereodivergent approach for the formation of 4-hydroxy-2,6-substituted tetrahydropyran rings has been demonstrated by the total syntheses of the anti-osteoporotic natural products diospongin A and
On the Relationship between Sialomucin and Sulfomucin Expression and Hydrogenotrophic Microbes in the Human Colonic Mucosa
The colonic mucus layer is comprised primarily of acidomucins, which provide viscous properties and can be broadly classified into sialomucins or sulfomucins based on the presence of terminating sialic acid or sulfate groups. Differences in acidomucin chemotypes have been observed in diseases such as colorectal cancer and inflammatory bowel disease, and variation in sialo- and sulfomucin content may influence microbial colonization. For example, sulfate derived from sulfomucin degradation may promote the colonization of sulfate-reducing bacteria (SRB), which through sulfate respiration generate the genotoxic gas hydrogen sulfide. Here, paired biopsies from right colon, left colon, and rectum of 20 subjects undergoing routine screening colonoscopies were collected to enable parallel histochemical and microbiological studies. Goblet cell sialo- and sulfomucins in each biopsy were distinguished histochemically and quantified. Quantitative PCR and multivariate analyses were used to examine the abundance of hydrogenotrophic microbial groups and SRB genera relative to acidomucin profiles. Regional variation was observed in sialomucins and sulfomucins with the greatest abundance of each found in the rectum. Mucin composition did not appear to influence the abundance of SRB or other hydrogenotrophic microbiota but correlated with the composition of different SRB genera. A higher sulfomucin proportion correlated with higher quantities of Desulfobacter, Desulfobulbus and Desulfotomaculum, relative to the predominant Desulfovibrio genus. Thus, acidomucin composition may influence bacterial sulfate respiration in the human colon, which may in turn impact mucosal homeostasis. These results stress the need to consider mucus characteristics in the context of studies of the microbiome that target intestinal diseases
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