155 research outputs found
A generalization of Hausdorff dimension applied to Hilbert cubes and Wasserstein spaces
A Wasserstein spaces is a metric space of sufficiently concentrated
probability measures over a general metric space. The main goal of this paper
is to estimate the largeness of Wasserstein spaces, in a sense to be precised.
In a first part, we generalize the Hausdorff dimension by defining a family of
bi-Lipschitz invariants, called critical parameters, that measure largeness for
infinite-dimensional metric spaces. Basic properties of these invariants are
given, and they are estimated for a naturel set of spaces generalizing the
usual Hilbert cube. In a second part, we estimate the value of these new
invariants in the case of some Wasserstein spaces, as well as the dynamical
complexity of push-forward maps. The lower bounds rely on several embedding
results; for example we provide bi-Lipschitz embeddings of all powers of any
space inside its Wasserstein space, with uniform bound and we prove that the
Wasserstein space of a d-manifold has "power-exponential" critical parameter
equal to d.Comment: v2 Largely expanded version, as reflected by the change of title; all
part I on generalized Hausdorff dimension is new, as well as the embedding of
Hilbert cubes into Wasserstein spaces. v3 modified according to the referee
final remarks ; to appear in Journal of Topology and Analysi
SKA HI end2end simulation
The current status of the HI simulation efforts is presented, in which a self
consistent simulation path is described and basic equations to calculate array
sensitivities are given. There is a summary of the SKA Design Study (SKADS) sky
simulation and a method for implementing it into the array simulator is
presented. A short overview of HI sensitivity requirements is discussed and
expected results for a simulated HI survey are presented.Comment: 7 pages, 6 figues, need skads2009.cls file to late
The calculus of thermodynamical formalism
Given an onto map T acting on a metric space and an appropriate Banach space of functions X./, one classically constructs for each potential A 2 X a transfer operator LA acting on X./. Under suitable hypotheses, it is well-known that LA has a maximal eigenvalue A, has a spectral gap and defines a unique Gibbs measure A. Moreover there is a unique normalized potential of the form B D ACf f T Cc acting as a representative of the class of all potentials defining the same Gibbs measure. The goal of the present article is to study the geometry of the set N of normalized potentials, of the normalization map A 7! B, and of the Gibbs map A 7! A. We give an easy proof of the fact that N is an analytic submanifold of X and that the normalization map is analytic; we compute the derivative of the Gibbs map; and we endow N with a natural weak Riemannian metric (derived from the asymptotic variance) with respect to which we compute the gradient flow induced by the pressure with respect to a given potential, e.g. the metric entropy functional. We also apply these ideas to recover in a wide setting existence and uniqueness of equilibrium states, possibly under constraints
Expanding e-MERLIN with the Goonhilly Earth Station
A consortium of universities has recently been formed with the goal of using
the decommissioned telecommunications infrastructure at the Goonhilly Earth
Station in Cornwall, UK, for astronomical purposes. One particular goal is the
introduction of one or more of the ~30-metre parabolic antennas into the
existing e-MERLIN radio interferometer. This article introduces this scheme and
presents some simulations which quantify the improvements that would be brought
to the e-MERLIN system. These include an approximate doubling of the spatial
resolution of the array, an increase in its N-S extent with strong implications
for imaging the most well-studied equatorial fields, accessible to ESO
facilities including ALMA. It also increases the overlap between the e-MERLIN
array and the European VLBI Network. We also discuss briefly some niche science
areas in which an e-MERLIN array which included a receptor at Goonhilly would
be potentially world-leading, in addition to enhancing the existing potential
of e-MERLIN in its role as a Square Kilometer Array pathfinder instrument.Comment: 7 pages, 3 figures, to appear in the proceedings of "Astronomy with
megastructures: Joint science with the E-ELT and SKA", 10-14 May 2010, Crete,
Greece (Eds: Isobel Hook, Dimitra Rigopoulou, Steve Rawlings and Aris
Karastergiou
Goonhilly: a new site for e-MERLIN and the EVN
The benefits for the e-MERLIN and EVN arrays of using antennae at the
satellite communication station at Goonhilly in Cornwall are discussed. The
location of this site - new to astronomy - will provide an almost equal
distribution of long baselines in the east-west- and north-south directions,
and opens up the possibility to get significantly improved observations of
equatorial fields with e-MERLIN. These additional baselines will improve the
sensitivity on a set of critical spatial scales and will increase the angular
resolution of e-MERLIN by a factor of two. e-MERLIN observations, including
many allocated under the e-MERLIN Legacy programme, will benefit from the
enhanced angular resolution and imaging capability especially for sources close
to or below the celestial equator (where ESO facilities such as ALMA will
operate) of including the Goonhilly telescopes. Furthermore, the baselines
formed between Goonhilly and the existing stations will close the gap between
the baselines of e-MERLIN and those of the European VLBI Network (EVN) and
therefore enhance the legacy value of e-MERLIN datasets.Comment: 10 pages, 2 figue
MESMER: MeerKAT Search for Molecules in the Epoch of Reionization
[Abridged] Observations of molecular gas at all redshifts are critical for
measuring the cosmic evolution in molecular gas density and understanding the
star-formation history of the Universe. The 12CO molecule (J=1-0 transition =
115.27 GHz) is the best proxy for extragalactic H2, which is the gas reservoir
from which star formation occurs, and has been detected out to z~6. Typically,
redshifted high-J lines are observed at mm-wavelengths, the most commonly
targeted systems exhibiting high SFRs (e.g. submm galaxies), and far-IR-bright
QSOs. While the most luminous objects are the most readily observed, detections
of more typical galaxies with modest SFRs are essential for completing the
picture. ALMA will be revolutionary in terms of increasing the detection rate
and pushing the sensitivity limit down to include such galaxies, however the
limited FoV when observing at such high frequencies makes it difficult to use
ALMA for studies of the large-scale structure traced out by molecular gas in
galaxies. This article introduces a strategy for a systematic search for
molecular gas during the EoR (z~7 and above), capitalizing on the fact that the
J=1-0 transition of 12CO enters the upper bands of cm-wave instruments at
high-z. The FoV advantage gained by observing at such frequencies, coupled with
modern broadband correlators allows significant cosmological volumes to be
probed on reasonable timescales. In this article we present an overview of our
future observing programme which has been awarded 6,500 hours as one of the
Large Survey Projects for MeerKAT, the forthcoming South African SKA pathfinder
instrument. Its large FoV and correlator bandwidth, and high-sensitivity
provide unprecedented survey speed for such work. An existing astrophysical
simulation is coupled with instrumental considerations to demonstrate the
feasibility of such observations and predict detection rates.Comment: 7 pages, 4 figures, to appear in the proceedings of "Astronomy with
megastructures: Joint science with the E-ELT and SKA", 10-14 May 2010, Crete,
Greece (Eds: Isobel Hook, Dimitra Rigopoulou, Steve Rawlings and Aris
Karastergiou
Bacterial toxin-triggered release of antibiotics from capsosomes protects a fly model from lethal methicillin-resistant Staphylococcus aureus (MRSA) infection
Antibiotic resistance is a severe global health threat and hence demands rapid action to develop novel therapies, including microscale drug delivery systems. Herein, a hierarchical microparticle system is developed to achieve bacteria-activated single- and dual-antibiotic drug delivery for preventing methicillin-resistant Staphylococcus aureus (MRSA) bacterial infections. The designed system is based on a capsosome structure, which consists of a mesoporous silica microparticle coated in alternating layers of oppositely charged polymers and antibiotic-loaded liposomes. The capsosomes are engineered and shown to release their drug payloads in the presence of MRSA toxins controlled by the Agr quorum sensing system. MRSA-activated single drug delivery of vancomycin and synergistic dual delivery of vancomycin together with an antibacterial peptide successfully kills MRSA in vitro. The capability of capsosomes to selectively deliver their cargo in the presence of bacteria, producing a bactericidal effect to protect the host organism, is confirmed in vivo using a Drosophila melanogaster MRSA infection model. Thus, the capsosomes serve as a versatile multidrug, subcompartmentalized microparticle system for preventing antibiotic-resistant bacterial infections, with potential applications to protect wounds or medical device implants from infections
Mindfulness training for depressed older adults using smartphone technology: Protocol for a fully remote precision clinical trial
BACKGROUND: Precision medicine, optimized interventions, and access to care are catchphrases for the future of behavioral treatments. Progress has been slow due to the dearth of clinical trials that optimize interventions\u27 benefits, individually tailor interventions to meet individual needs and preferences, and lead to rapid implementation after effectiveness is demonstrated. Two innovations have emerged to meet these challenges: fully remote trials and precision clinical trials.
OBJECTIVE: This paper provides a detailed description of Mindful MyWay, a study designed to test online mindfulness training in older adults with depression. Consistent with the concept of fully remote trials using a smartphone app, the study requires no in-person contact and can be conducted with participants anywhere in the United States. Based upon the precision medicine framework, the study assesses participants using high-frequency assessments of symptoms, cognitive performance, and patient preferences to both understand the individualized nature of treatment response and help individually tailor the intervention.
METHODS: Mindful MyWay is an open-label early-phase clinical trial for individuals 65 years and older with current depression. A smartphone app was developed to help coordinate the study, deliver the intervention, and evaluate the acceptability of the intervention, as well as predictors and outcomes of it. The curriculum for the fully remote intervention parallels the mindfulness-based stress reduction curriculum, a protocolized group-based mindfulness training that is typically provided in person. After consent and screening, participants download The Healthy Mind Lab mobile health smartphone app from the Apple App Store, allowing them to complete brief smartphone-based assessments of depressive symptoms and cognitive performance 4 times each day for 4 weeks prior to and after completing the intervention. The intervention consists of an introduction video and 10 weekly mindfulness training sessions, with the expectation to practice mindfulness at home daily. The app collects participant preference data throughout the 10-week intervention period; these high-frequency assessments identify participants\u27 individually dynamic preferences toward the goal of optimizing the intervention in future iterations.
RESULTS: Participant recruitment and data collection began in March 2019. Final end point assessments will be collected in May 2022. The paper describes lessons learned regarding the critical role of early-phase testing prior to moving to a randomized trial.
CONCLUSIONS: The Mindful MyWay study is an exemplar of innovative clinical trial designs that use smartphone technology in behavioral and neuropsychiatric conditions. These include fully remote studies that can recruit throughout the United States, including hard-to-access areas, and collect high-frequency data, which is ideal for idiographic assessment and individualized intervention optimization. Our findings will be used to modify our methods and inform future randomized controlled trials within a precision medicine framework.
TRIAL REGISTRATION: ClinicalTrials.gov NCT03922217; https://clinicaltrials.gov/ct2/show/NCT03922217.
INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/39233
Mapping the SKA Simulated Skies with the S3-Tools
The S3-Tools are a set of Python-based routines and interfaces whose purpose is to provide user-friendly access to the SKA Simulated Skies (S3) set of simulations, an effort led by the University of Oxford in the framework of the European Union's SKADS program (http://www.skads-eu.org). The databases built from the S3 simulations are hosted by the Oxford e-Research Center (OeRC), and can be accessed through a web portal at http://s-cubed.physics.ox.ac.uk. This paper focuses on the practical steps involved to make radio images from the S3-SEX and S3-SAX simulations using the S3-Map tool and should be taken as a broad overview. For a more complete description, the interested reader should look up the user's guide. The output images can then be used as input to instrument simulators, e.g. to assess technical designs and observational strategies for the SKA and SKA pathfinders
Epidermal Growth Factor–PEG Functionalized PAMAM-Pentaethylenehexamine Dendron for Targeted Gene Delivery Produced by Click Chemistry
Aim of this study was the site-specific conjugation of an epidermal growth factor (EGF)-polyethylene glycol (PEG) chain by click chemistry onto a poly(amido amine) (PAMAM) dendron, as a key step toward defined multifunctional carriers for targeted gene delivery. For this purpose, at first propargyl amine cored PAMAM dendrons with ester ends were synthesized. The chain terminal ester groups were then modified by oligoamines with different secondary amino densities. The oligoamine-modified PAMAM dendrons were well biocompatible, as demonstrated in cytotoxicity assays. Among the different oligoamine-modified dendrons, PAMAM-pentaethylenehexamine (PEHA) dendron polyplexes displayed the best gene transfer ability. Conjugation of PAMAM-PEHA dendron with PEG spacer was conducted via click reaction, which was performed before amidation with PEHA. The resultant PEG-PAMAM-PEHA copolymer was then coupled with EGF ligand. pDNA transfections in HuH-7 hepatocellular carcinoma cells showed a 10-fold higher efficiency with the polyplexes containing conjugated EGF as compared to the ligand-free ones, demonstrating the concept of ligand targeting. Overall gene transfer efficiencies, however, were moderate, suggesting that additional measures for overcoming subsequent intracellular bottlenecks in delivery have to be taken
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