| 1. |
- Algaba, Juan-Carlos, et al.
(författare)
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Broadband Multi-wavelength Properties of M87 during the 2017 Event Horizon Telescope Campaign
- 2021
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 911:1
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Forskningsöversikt (refereegranskat)abstract
- In 2017, the Event Horizon Telescope (EHT) Collaboration succeeded in capturing the first direct image of the center of the M87 galaxy. The asymmetric ring morphology and size are consistent with theoretical expectations for a weakly accreting supermassive black hole of mass ∼6.5 × 109 M o˙. The EHTC also partnered with several international facilities in space and on the ground, to arrange an extensive, quasi-simultaneous multi-wavelength campaign. This Letter presents the results and analysis of this campaign, as well as the multi-wavelength data as a legacy data repository. We captured M87 in a historically low state, and the core flux dominates over HST-1 at high energies, making it possible to combine core flux constraints with the more spatially precise very long baseline interferometry data. We present the most complete simultaneous multi-wavelength spectrum of the active nucleus to date, and discuss the complexity and caveats of combining data from different spatial scales into one broadband spectrum. We apply two heuristic, isotropic leptonic single-zone models to provide insight into the basic source properties, but conclude that a structured jet is necessary to explain M87's spectrum. We can exclude that the simultaneous γ-ray emission is produced via inverse Compton emission in the same region producing the EHT mm-band emission, and further conclude that the γ-rays can only be produced in the inner jets (inward of HST-1) if there are strongly particle-dominated regions. Direct synchrotron emission from accelerated protons and secondaries cannot yet be excluded.
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| 2. |
- Stanaway, Jeffrey D., et al.
(författare)
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Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks for 195 countries and territories, 1990-2017: A systematic analysis for the Global Burden of Disease Study 2017
- 2018
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Ingår i: The Lancet. - 1474-547X .- 0140-6736. ; 392:10159, s. 1923-1994
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Tidskriftsartikel (refereegranskat)abstract
- Background The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2017 comparative risk assessment (CRA) is a comprehensive approach to risk factor quantification that offers a useful tool for synthesising evidence on risks and risk-outcome associations. With each annual GBD study, we update the GBD CRA to incorporate improved methods, new risks and risk-outcome pairs, and new data on risk exposure levels and risk- outcome associations. Methods We used the CRA framework developed for previous iterations of GBD to estimate levels and trends in exposure, attributable deaths, and attributable disability-adjusted life-years (DALYs), by age group, sex, year, and location for 84 behavioural, environmental and occupational, and metabolic risks or groups of risks from 1990 to 2017. This study included 476 risk-outcome pairs that met the GBD study criteria for convincing or probable evidence of causation. We extracted relative risk and exposure estimates from 46 749 randomised controlled trials, cohort studies, household surveys, census data, satellite data, and other sources. We used statistical models to pool data, adjust for bias, and incorporate covariates. Using the counterfactual scenario of theoretical minimum risk exposure level (TMREL), we estimated the portion of deaths and DALYs that could be attributed to a given risk. We explored the relationship between development and risk exposure by modelling the relationship between the Socio-demographic Index (SDI) and risk-weighted exposure prevalence and estimated expected levels of exposure and risk-attributable burden by SDI. Finally, we explored temporal changes in risk-attributable DALYs by decomposing those changes into six main component drivers of change as follows: (1) population growth; (2) changes in population age structures; (3) changes in exposure to environmental and occupational risks; (4) changes in exposure to behavioural risks; (5) changes in exposure to metabolic risks; and (6) changes due to all other factors, approximated as the risk-deleted death and DALY rates, where the risk-deleted rate is the rate that would be observed had we reduced the exposure levels to the TMREL for all risk factors included in GBD 2017.
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| 3. |
- Giffin, Daniel B., et al.
(författare)
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Hails: Protecting Data Privacy in Untrusted Web Applications
- 2012
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Ingår i: Symposium on Operating Systems Design and Implementation.
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Konferensbidrag (refereegranskat)abstract
- Modern extensible web platforms like Facebook andYammer depend on third-party software to offer a richexperience to their users. Unfortunately, users running athird-party “app” have little control over what it does withtheir private data. Today’s platforms offer only ad-hocconstraints on app behavior, leaving users an unfortunatetrade-off between convenience and privacy. A principledapproach to code confinement could allow the integration of untrusted code while enforcing flexible, end-to-endpolicies on data access. This paper presents a new webframework, Hails, that adds mandatory access control anda declarative policy language to the familiar MVC architecture. We demonstrate the flexibility of Hails throughGitStar.com, a code-hosting website that enforces robust privacy policies on user data even while allowing untrusted apps to deliver extended features to users.
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| 4. |
- Giffin, Daniel, et al.
(författare)
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Hails: Protecting data privacy in untrusted web applications
- 2017
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Ingår i: Journal of Computer Security. - 0926-227X. ; 25:4-5, s. 427-461
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Tidskriftsartikel (refereegranskat)abstract
- Many modern web-platforms are no longer written by a single entity, such as a company or individual, but consist of a trusted core that can be extended by untrusted third-party authors. Examples of this approach include Facebook, Yammer, and Salesforce. Unfortunately, users running third-party "apps" have little control over what the apps can do with their private data. Today's platforms offer only ad hoc constraints on app behavior, leaving users an unfortunate trade-off between convenience and privacy. A principled approach to code confinement could allow the integration of untrusted code while enforcing flexible, end-to-end policies on data access. This paper presents a new framework, Hails, for building web platforms, that adds mandatory access control and a declarative policy language to the familiar MVC architecture. We demonstrate the flexibility of Hails by building several platforms, including GitStar, a code-hosting website that enforces robust privacy policies on user data even while allowing untrusted apps to deliver extended features to users.
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| 5. |
- Hays, M., et al.
(författare)
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Coherent manipulation of an Andreev spin qubit
- 2021
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 373:6553, s. 430-433
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Tidskriftsartikel (refereegranskat)abstract
- Two promising architectures for solid-state quantum information processing are based on electron spins electrostatically confined in semiconductor quantum dots and the collective electrodynamic modes of superconducting circuits. Superconducting electrodynamic qubits involve macroscopic numbers of electrons and offer the advantage of larger coupling, whereas semiconductor spin qubits involve individual electrons trapped in microscopic volumes but are more difficult to link. We combined beneficial aspects of both platforms in the Andreev spin qubit: the spin degree of freedom of an electronic quasiparticle trapped in the supercurrent-carrying Andreev levels of a Josephson semiconductor nanowire. We performed coherent spin manipulation by combining single-shot circuit–quantum-electrodynamics readout and spin-flipping Raman transitions and found a spin-flip time TS = 17 microseconds and a spin coherence time T2E = 52 nanoseconds. These results herald a regime of supercurrent-mediated coherent spin-photon coupling at the single-quantum level.
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