51 research outputs found
Auditing News Curation Systems: A Case Study Examining Algorithmic and Editorial Logic in Apple News
This work presents an audit study of Apple News as a sociotechnical news
curation system that exercises gatekeeping power in the media. We examine the
mechanisms behind Apple News as well as the content presented in the app,
outlining the social, political, and economic implications of both aspects. We
focus on the Trending Stories section, which is algorithmically curated, and
the Top Stories section, which is human-curated. Results from a crowdsourced
audit showed minimal content personalization in the Trending Stories section,
and a sock-puppet audit showed no location-based content adaptation. Finally,
we perform an extended two-month data collection to compare the human-curated
Top Stories section with the algorithmically curated Trending Stories section.
Within these two sections, human curation outperformed algorithmic curation in
several measures of source diversity, concentration, and evenness. Furthermore,
algorithmic curation featured more "soft news" about celebrities and
entertainment, while editorial curation featured more news about policy and
international events. To our knowledge, this study provides the first
data-backed characterization of Apple News in the United States.Comment: Preprint, to appear in Proceedings of the Fourteenth International
AAAI Conference on Web and Social Media (ICWSM 2020
Transport of sulfur dioxide from the Asian Pacific Rim to the North Pacific troposphere
The NASA Pacific Exploratory Mission over the Western Pacific Ocean (PEM-West B) field experiment provided an opportunity to study sulfur dioxide (SO2) in the troposphere over the western Pacific Ocean from the tropics to 60°N during FebruaryâMarch 1993. The large suite of chemical and physical measurements yielded a complex matrix in which to understand the distribution of sulfur dioxide over the western Pacific region. In contrast to the late summer period of Pacific Exploratory Mission-West A (PEM-West A) (1991) over this same area, SO2showed little increase with altitude, and concentrations were much lower in the free troposphere than during the PEM-West B period. Volcanic impacts on the upper troposphere were again found as a result of deep convection in the tropics. Extensive emission of SO2 from the Pacific Rim land masses were primarily observed in the lower well-mixed part of the boundary layer but also in the upper part of the boundary layer. Analyses of the SO2 data with aerosol sulfate, beryllium-7, and lead-210 indicated that SO2 contributed to half or more of the observed total oxidized sulfur (SO2 plus aerosol sulfate) in free tropospheric air. The combined data set suggests that SO2 above 8.5 km is transported from the surface but with aerosol sulfate being removed more effectively than SO2. Cloud processing and rain appeared to be responsible for lower SO2 levels between 3 and 8.5 km than above or below this region
From Invisibility to Readability: Recovering the Ink of Herculaneum
The noninvasive digital restoration of ancient texts written in carbon black ink and hidden inside artifacts has proven elusive, even with advanced imaging techniques like x-ray-based micro-computed tomography (micro-CT). This paper identifies a crucial mistaken assumption: that micro-CT data fails to capture any information representing the presence of carbon ink. Instead, we show new experiments indicating a subtle but detectable signature from carbon ink in micro-CT. We demonstrate a new computational approach that captures, enhances, and makes visible the characteristic signature created by carbon ink in micro-CT. This previously unseen evidence of carbon inks, which can now successfully be made visible, is a discovery that can lead directly to the noninvasive digital recovery of the lost texts of Herculaneum
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Carbonyl sulfide and carbon disulfide: Large-scale distributions over the western Pacific and emissions from Asia during TRACE-P
An extensive set of carbonyl sulfide (OCS) and carbon disulfide (CS2) observations were made as part of the NASA Transport and Chemical Evolution over the Pacific (TRACE-P) project, which took place in the early spring 2001. TRACE-P sampling focused on the western Pacific region but in total included the geographic region 110°E to 290°E longitude, 5°N to 50°N latitude, and 0â12 km altitude. Substantial OCS and CS2 enhancements were observed for a great many air masses of Chinese and Japanese origin during TRACE-P. Over the western Pacific, mean mixing ratios of long-lived OCS and shorter-lived CS2 showed a gradual decrease by about 10% and a factor of 5â10, respectively, from the surface to 8â10 km altitude, presumably because land-based sources dominated their distribution during February through April 2001. The highest mean OCS and CS2levels (580 and 20 pptv, respectively, based on 2.5° Ă 2.5° latitude bins) were observed below 2 km near the coast of Asia, at latitudes between 25°N and 35°N, where urban Asian outflow was strongest. Ratios of OCS versus CO for continental SE Asia were much lower compared to Chinese and Japanese signatures and were strongly associated with biomass burning/biofuel emissions. We present a new inventory of anthropogenic Asian emissions (including biomass burning) for OCS and CS2 and compare it to emission estimates based on regional relationships of OCS and CS2 to CO and CO2. The OCS and CS2 results for the two methods compare well for continental SE Asia and Japan plus Korea and also for Chinese CS2 emissions. However, it appears that the inventory underestimates Chinese emissions of OCS by about 30â100%. This difference may be related to the fact that we did not include natural sources such as wetland emissions in our inventory, although the contributions from such sources are believed to be at a seasonal low during the study period. Uncertainties in OCS emissions from Chinese coal burning, which are poorly characterized, likely contribute to the discrepancy
Airborne sampling of aerosol particles: Comparison between surface sampling at Christmas Island and P-3 sampling during PEM-Tropics B
Bulk aerosol sampling of soluble ionic compounds from the NASA Wallops Island P-3 aircraft and a tower on Christmas Island during PEM-Tropics B provides an opportunity to assess the magnitude of particle losses in the University of New Hampshire airborne bulk aerosol sampling system. We find that most aerosol-associated ions decrease strongly with height above the sea surface, making direct comparisons between mixing ratios at 30 m on the tower and the lowest flight level of the P-3 (150 m) open to interpretation. Theoretical considerations suggest that vertical gradients of sea-salt aerosol particles should show exponential decreases with height. Observed gradients of Na+ and Mg2+, combining the tower observations with P-3 samples collected below 1 km, are well described by exponential decreases (r values of 0.88 and 0.87, respectively), though the curve fit underestimates average mixing ratios at the surface by 25%. Cascade impactor samples collected on the tower show that \u3e99% of the Na+ and Mg2+mass is on supermicron particles, 65% is in the 1â6 micron range, and just 20% resides on particles with diameters larger than 9 microns. These results indicate that our airborne aerosol sampling probes must be passing particles up to at least 6 microns with high efficiency. We also observed that nss SO42â and NH4+, which are dominantly on accumulation mode particles, tended to decrease between 150 and 1000 m, but they were often considerably higher at the lowest P-3 sampling altitudes than at the tower. This finding is presently not well understood
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Atmospheric sampling of Supertyphoon Mireille with NASA DC-8 aircraft on September 27,1991, during PEM-West A
The DC-8 mission of September 27, 1991, was designed to sample air flowing into Typhoon Mireille in the boundary layer, air in the upper tropospheric eye region, and air emerging from the typhoon and ahead of the system, also in the upper troposphere. The objective was to find how a typhoon redistributes trace constituents in the West Pacific region and whether any such redistribution is important on the global scale. The boundary layer air (300 m), in a region to the SE of the eye, contained low mixing ratios of the tracer species O3, CO, C2H6, C2H2, C3H8, C6H6and CS2 but high values of dimethylsulfide (DMS). The eye region relative to the boundary layer, showed somewhat elevated levels of CO, substantially increased levels of O3, CS2 and all nonmethane hydrocarbons (NMHCs), and somewhat reduced levels of DMS. Ahead of the eye, CO and the NMHCs remained unchanged, O3 and CS2 showed a modest decrease, and DMS showed a substantial decrease. There was no evidence from lidar cross sections of ozone for the downward entrainment of stratospheric air into the eye region; these sections show that low ozone values were measured in the troposphere. The DMS data suggest substantial entrainment of boundary layer air into the system, particularly into the eye wall region. Estimates of the DMS sulphur flux between the boundary layer and the free troposphere, based on computations of velocity potential and divergent winds, gave values of about 69 ÎŒg S mâ2 dâ1 averaged over a 17.5° grid square encompassing the typhoon. A few hours after sampling with the DC-8, Mireille passed over Oki Island, just to the north of Japan, producing surface values of ozone of 5.5 ppbv. These O3 levels are consistent with the low tropospheric values found by lidar and are more typical of equatorial regions. We suggest that the central eye region may act like a Taylor column which has moved poleward from low latitudes. The high-altitude photochemical environment within Typhoon Mireille was found to be quite active as evidenced by significant levels of measured gas phase H2O2 and CH3OOH and model-computed levels of OH
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Ozone and aerosol distributions and air mass characteristics over the South Pacific during the burning season
In situ and laser remote measurements of gases and aerosols were made with airborne instrumentation to establish a baseline chemical signature of the atmosphere above the South Pacific Ocean during the NASA Global Tropospheric Experiment (GTE)/Pacific Exploratory MissionâTropics A (PEMâTropics A) conducted in AugustâOctober 1996. This paper discusses general characteristics of the air masses encountered during this experiment using an airborne lidar system for measurements of the largeâscale variations in ozone (O3) and aerosol distributions across the troposphere, calculated potential vorticity (PV) from the European Centre for MediumâRange Weather Forecasting (ECMWF), and in situ measurements for comprehensive air mass composition. Between 8°S and 52°S, biomass burning plumes containing elevated levels of O3, over 100 ppbv, were frequently encountered by the aircraft at altitudes ranging from 2 to 9 km. Air with elevated O3 was also observed remotely up to the tropopause, and these air masses were observed to have no enhanced aerosol loading. Frequently, these air masses had some enhanced PV associated with them, but not enough to explain the observed O3 levels. A relationship between PV and O3 was developed from cases of clearly defined O3 from stratospheric origin, and this relationship was used to estimate the stratospheric contribution to the air masses containing elevated O3 in the troposphere. The frequency of observation of the different air mass types and their average chemical composition is discussed in this paper
Global Norms, Local Activism, and Social Movement Outcomes: Global Human Rights and Resident Koreans in Japan
The authors integrate social movement outcomes research and the world society approach to build a theoretical model to examine the impact of global and local factors on movement outcomes. Challenging the current research on policy change, which rarely examines the effects of global norms and local activism in one analysis, they argue (1) that global regimes empower and embolden local social movements and increase pressure on target governments from below, and (2) that local activists appeal to international forums with help from international activists to pressure the governments from above. When the pressures from the top and the bottom converge, social movements are more likely to succeed. Furthermore, these pressures are stronger in countries integrated into global society and on issues with strong global norms. The empirical analysis of social movements by resident Koreans in Japan advocating for four types of human rightsâcivil, political, social/economic, and culturalâdemonstrates that the movements produced more successes as Japan\u27s involvement in the international human rights regime expanded since the late 1970s, and that activism on issues with strong global norms achieved greater successes. The analysis also shows that lack of cohesive domestic activism can undercut the chances of social movements\u27 success even with strong global norms on the issue
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