984 research outputs found
Empowering users to control their privacy in context-aware system through interactive consent
Context-aware systems adapt their behaviour based on the context a user is in. Since context is potentially privacy sensitive information, users should be empowered to control how much of their context they are willing to share, under what conditions and for what purpose. We propose an interactive consent mechanism that allows this. It is interactive in the sense that users are asked for consent when a request for their context information is received. Our interactive consent mechanism complements a more traditional pre-configuration approach. We describe the architecture, the implementation of our interactive consent mechanism and a use case
In Conversation with Mubin Shaikh: From Salafi Jihadist to Undercover Agent inside the "Toronto 18" Terrorist Group
This interview with former undercover agent Mubin Shaikh can help academics and security practitioners understand the key role played and the challenges faced by covert human intelligence sources within domestic terrorist groups. The interview highlights the identity crisis, the personal factors, and the allure of jihadi militancy that initially drove Shaikh to join a Salafi jihadist group. It investigates Shaikhâs process of disengagement from the Salafi jihadist belief system and his rediscovery of a moderate, inclusive, and benevolent form of Islam. It explores his work as an undercover agent for the Canadian Security Intelligence Service, the Royal Canadian Mounted Police, and the Integrated National Security Enforcement Team responsible for disrupting domestic terrorist groups. The âToronto 18â terrorist cell, the key role played by undercover agents in preventing terrorist action, and the challenges posed by entrapment are also discussed
Baseline meniscal extrusion associated with incident knee osteoarthritis after 30 months in overweight and obese women
Objective: To investigate the association between baseline meniscal extrusion and the incidence of knee osteoarthritis (KOA) after 30 months in a high-risk population of overweight and obese women, free of clinical and radiological KOA at baseline. Methods: 407 middle-aged overweight women (body mass index - BMI â„ 27 kg/m2) were evaluated at baseline and after 30 months of follow-up. Meniscal extrusion was defined as grade â„2 on MRI according to MRI Osteoarthritis Knee Score (MOAKS). The primary outcome measure was KOA after 30 months follow-up, defined using the following criteria: either incidence of radiographic KOA (Kellgren & Lawrence grade 2 or higher), or clinical osteoarthritis (OA) according to the American College of Radiology (ACR) criteria, or medial or lateral joint space narrowing (JSN) of â„1.0 mm. Using generalized estimating equations (GEE), we determined the association between knees with and without meniscal extrusion and both outcomes, corrected for the baseline differences. Results: 640 knees were available at baseline of which 24% (153) had meniscal extrusion. There was a significantly higher incidence of KOA according to the primary outcome measure in women with meniscal extrusion compared to those without extrusion (28.8%, odds ratio - OR 2.39, 95% CI 1.53, 3.73). A significantly higher incidence was found for the development of radiographic KOA (12.4%, OR 2.61, 95% CI 1.11, 6.13) and medial JSN (11.8%, OR 3.19, 95% CI 1.59, 6.41). Meniscal extrusion was not significantly associated with clinical KOA and lateral JSN. Conclusion: Meniscal extrusion was associated with a significantly higher incidence of KOA, providing an interesting target for early detection of individuals at risk for developing KOA
The structure of the protoplanetary disk surrounding three young intermediate mass stars. II. Spatially resolved dust and gas distribution
[Abridged] We present the first direct comparison of the distribution of the
gas, as traced by the [OI] 6300 AA emission, and the dust, as traced by the 10
micron emission, in the protoplanetary disk around three intermediate-mass
stars: HD 101412, HD 135344 B and HD 179218. N-band visibilities were obtained
with VLTI/MIDI. Simple geometrical models are used to compare the dust emission
to high-resolution optical spectra in the 6300 AA [OI] line of the same
targets. The disks around HD 101412 and HD 135344 B appear strongly flared in
the gas, but self-shadowed in the dust beyond ~ 2 AU. In both systems, the 10
micron emission is rather compact (< 2 AU) while the [OI] brightness profile
shows a double peaked structure. The inner peak is strongest and is consistent
with the location of the dust, the outer peak is fainter and is located at 5-10
AU. Spatially extended PAH emission is found in both disks. The disk around HD
179218 is flared in the dust. The 10 micron emission emerges from a double
ring-like structure with the first ring peaking at ~ 1 AU and the second at ~
20 AU. No dust emission is detected between ~ 3 -- 15 AU. The oxygen emission
seems also to come from a flared structure, however, the bulk of this emission
is produced between ~ 1 -- 10 AU. This could indicate a lack of gas in the
outer disk or could be due to chemical effects which reduce the abundance of OH
-- the parent molecule of the observed [OI] emission -- further away from the
star. The three systems, HD 179218, HD 135344 B and HD 101412, may form an
evolutionary sequence: the disk initially flared becomes flat under the
combined action of gas-dust decoupling, grain growth and dust settling.Comment: Accepted for publication in A&
First results of the Herschel Key Program 'Dust, Ice and Gas in Time': Dust and Gas Spectroscopy of HD 100546
We present far-infrared spectroscopic observations, taken with the
Photodetector Array Camera and Spectrometer (PACS) on the Herschel Space
Observatory, of the protoplanetary disk around the pre-main-sequence star HD
100546. These observations are the first within the DIGIT Herschel key program,
which aims to follow the evolution of dust, ice, and gas from young stellar
objects still embedded in their parental molecular cloud core, through the
final pre-main-sequence phases when the circumstellar disks are dissipated.
Our aim is to improve the constraints on temperature and chemical composition
of the crystalline olivines in the disk of HD 100546 and to give an inventory
of the gas lines present in its far-infrared spectrum. The 69 \mu\m feature is
analyzed in terms of position and shape to derive the dust temperature and
composition. Furthermore, we detected 32 emission lines from five gaseous
species and measured their line fluxes. The 69 \mu\m emission comes either from
dust grains with ~70 K at radii larger than 50 AU, as suggested by blackbody
fitting, or it arises from ~200 K dust at ~13 AU, close to the midplane, as
supported by radiative transfer models. We also conclude that the forsterite
crystals have few defects and contain at most a few percent iron by mass.
Forbidden line emission from [CII] at 157 \mu\m and [OI] at 63 and 145 \mu\m,
most likely due to photodissociation by stellar photons, is detected.
Furthermore, five H2O and several OH lines are detected. We also found high-J
rotational transition lines of CO, with rotational temperatures of ~300 K for
the transitions up to J=22-21 and T~800 K for higher transitions
Post conjunction detection of Pictoris b with VLT/SPHERE
With an orbital distance comparable to that of Saturn in the solar system,
\bpic b is the closest (semi-major axis \,9\,au) exoplanet that has
been imaged to orbit a star. Thus it offers unique opportunities for detailed
studies of its orbital, physical, and atmospheric properties, and of
disk-planet interactions. With the exception of the discovery observations in
2003 with NaCo at the Very Large Telescope (VLT), all following astrometric
measurements relative to \bpic have been obtained in the southwestern part of
the orbit, which severely limits the determination of the planet's orbital
parameters. We aimed at further constraining \bpic b orbital properties using
more data, and, in particular, data taken in the northeastern part of the
orbit.
We used SPHERE at the VLT to precisely monitor the orbital motion of beta
\bpic b since first light of the instrument in 2014. We were able to monitor
the planet until November 2016, when its angular separation became too small
(125 mas, i.e., 1.6\,au) and prevented further detection. We redetected \bpic b
on the northeast side of the disk at a separation of 139\,mas and a PA of
30 in September 2018. The planetary orbit is now well constrained.
With a semi-major axis (sma) of au (1 ), it
definitely excludes previously reported possible long orbital periods, and
excludes \bpic b as the origin of photometric variations that took place in
1981. We also refine the eccentricity and inclination of the planet. From an
instrumental point of view, these data demonstrate that it is possible to
detect, if they exist, young massive Jupiters that orbit at less than 2 au from
a star that is 20 pc away.Comment: accepted by A&
Reducing progression of knee OA features assessed by MRI in overweight and obese women: Secondary outcomes of a preventive RCT
Objective: To evaluate the preventive effects of a randomized controlled trial on progression of Magnetic Resonance Imaging (MRI) features of knee osteoarthritis (OA) in overweight and obese women. Design: In a 2 à 2 factorial design, 2.5 years effects of a diet and exercise program and of glucosamine sulphate (double-blind, placebo-controlled) were evaluated in 407 middle-aged women with body mass index (BMI) ℠27 kg/m2 without clinical signs of knee OA at baseline (ISRCTN 42823086). MRIs were scored with the MRI Osteoarthritis Knee Score (MOAKS). Progression was defined for bone marrow lesions (BMLs), cartilage defects, osteophytes, meniscal abnormalities and meniscal extrusion. Analyses on knee level were performed over the four intervention groups using adjusted Generalized Estimating Equations (GEE). Results: 687 knees of 347 women with mean age 55.7 years (±3.2 SD) and mean BMI 32.3 kg/m2 (±4.2 SD) were analyzed. Baseline prevalence was 64% for BMLs, 70% for cartilage defects, 24% for osteophytes, 66% for meniscal abnormalities and 52% for meniscal extrusions. The diet and exercise program + placebo intervention showed significantly less progression of meniscal extrusion compared to placebo only (12% vs 22%, OR 0.50, 95% CI [0.27-0.92]). The interventions did not result in significant differences on other OA MRI features. Conclusions: In subjects at high risk for future knee OA development, a diet and exercise program, glucosamine sulphate and their combination showed small and mainly non-significant effects on the progression of OA MRI features. Only progression of meniscal extrusion was significantly diminished by the diet and exercise program
Demographics of Protoplanetary Disks: A Simulated Population of Edge-on Systems
The structure of protoplanetary disks plays an essential role in planet
formation. Disks that are highly inclined, or ''edge-on'', are of particular
interest since their geometry provides a unique opportunity to study the disk's
vertical structure and radial extent. Candidate edge-on protoplanetary disks
are typically identified via their unique spectral energy distribution and
subsequently confirmed through high-resolution imaging. However, this selection
process is likely biased toward the largest, most massive disks, and the
resulting sample may not accurately represent the underlying disk population.
To investigate this, we generated a grid of protoplanetary disk models using
radiative transfer simulations and determined which sets of disk parameters
produce edge-on systems that could be recovered by aforementioned detection
techniques--i.e., identified by their spectral energy distribution and
confirmed through follow-up imaging with HST. In doing so, we adopt a
quantitative working definition of "edge-on disks" that is observation-driven
and agnostic about the disk inclination or other properties. Folding in
empirical disk demographics, we predict an occurrence rate of 6.2% for edge-on
disks and quantify biases towards highly inclined, massive disks. We also find
that edge-on disks are under-represented in samples of Spitzer-studied young
stellar objects, particularly for disks with M 0.5 .
Overall, our analysis suggests that several dozen edge-on disks remain
undiscovered in nearby star-forming regions, and provides a universal selection
process to identify edge-on disks for consistent, population-level demographic
studies.Comment: 20 pages, 6 figure
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