Surface boulder banding indicates martian debris-covered glaciers formed over multiple glaciations project data

Glacial landforms including lobate debris aprons are a globally distributed water ice reservoir on Mars preserving ice from past periods when high orbital obliquity permitted non-polar ice accumulation. Numerous studies have noted morphological similarities between lobate debris aprons and terrestrial debris-covered glaciers, an interpretation supported by radar observations. On both Earth and Mars, these landforms consist of a core of flowing ice covered by a rocky lag. Terrestrial debris-covered glaciers advance in response to climate forcing, driven by obliquity-paced changes to ice mass balance. However, on Mars, it is not known whether glacial landforms that were emplaced over the past 300-800 Ma formed during a single, long deposition event or during multiple glaciations. Here we show that boulders atop 45 lobate debris aprons exhibit no evidence of sequential comminution, but are clustered into bands that become more numerous with increasing latitude, debris apron length, and pole-facing flow orientation. Boulder bands are prominent at glacier headwalls, consistent with debris accumulation during the current martian interglacial. Terrestrial debris-covered glacier boulder bands occur near flow discontinuities caused by obliquity-driven hiatuses in ice accumulation that form internal debris layers. By analogy, we suggest that martian lobate debris aprons experienced multiple cycles of ice deposition, followed by destabilization of ice in the accumulation zone leading to boulder-dominated lenses, and subsequent ice deposition and continued flow. Correlation between latitude and boulder clustering suggests that ice mass balance works across global scales on Mars. Individual lobate debris aprons may preserve ice spanning multiple glacial/interglacial cycles

Local Standards, Behavioral Adjustments, and Welfare: Evaluating California\u27s Ocean-Going Vessel Fuel Rule

We examine how behavioral adjustments by regulated vessels affect welfare outcomes of a local fuel sulfur standard targeting particulate matter pollution from maritime transport. Our analysis combines one-minute scale data of vessel locations with location-specific marginal damages to obtain voyage-level measures of welfare outcomes. Exploiting the introduction of California\u27s Ocean-Going Vessel Fuel Rule, we find sharp reductions in fuel consumption in the regulated area and a considerable emission spillover in unregulated waters. Despite these adjustments, the rule generates net benefits of close to $1 billion over 29 months because the emission spillovers occur in low marginal damage areas

Hot and Cold Seasons in the Housing Market: Comment

Using American Housing Survey data from 1999 only, Ngai and Tenreyro (2014) show households who move in the summer occupy their home for longer and have fewer and less costly renovations soon after purchase, pointing to superior match quality during the thicker summer market. However, applying the same methods to other years of the American Housing Survey eliminates or substantially weakens these results. Furthermore, Ngai and Tenreyro’s result on duration of occupancy is driven in part by the particular way Ngai and Tenreyro measure duration in years, rather than months

Pb-Pb Dating of Terrestrial and Extraterrestrial Samples Using Resonance Ionization Mass Spectrometry

We are developing an in-situ, rock-dating spectrometer for spaceflight called the Chemistry, Organics, and Dating EXperiment (CODEX). CODEX will measure Rb-Sr ages on the Moon or Mars, and can be augmented to obtain Pb-Pb ages. Coupling Rb-Sr and Pb-Pb measurements broadens the suite of samples that can be dated, and could provide tests of concordance. Here we assess whether geochronologically meaningful Pb-Pb data could be measured in situ by tuning the prototype CODEX to acquire Pb-Pb data from a suite of well-characterized specimens from the Earth, Moon, and Mars. For Keuhl Lake zircon 91500 our 207Pb/206Pb age of 1090 ± 40 Ma is indistinguishable from the accepted age. In each of the Martian meteorites we studied, we could not resolve more than a single component of Pb, and could not uniquely determine ages. Nevertheless, our measurements were consistent with most previous studies of Pb in these meteorites. On the other hand, we determined 204.206,207 Pb isochron ages for all three lunar meteorites we studied. Our age for MIL 05035 is 3500 ± 200 Ma, within 2σ of published ages for this specimen, in spite of its having \u3c1 ppm Pb. LAP 02205 was contaminated by terrestrial Pb, but by filtering our data to exclude the most contaminated spots, we obtained an age of 3010 ± 70 Ma, coincident with published values. Finally, our age for NWA 032 is nearly 1000 Myr older than its age determined from other isotopic systems, and is supported by additional Pb measurements made after chemical leaching

An Interpretable Approach to Fake News Detection

Misinformation has long been a tool for political influence, but it has taken a new form in the information age: fake news. After exploding into public consciousness during the 2016 United States presidential election, fake news has become a reality of political life around the world, featuring heavily in the 2017 German election and the 2018 Brazilian election. Fake news poses a significant threat to civic society, and is too easily produced and quickly disseminated to be resolved by manual fact-checking. As such, fake news detection has received significant attention by machine learning and natural language processing researchers in the last years. Previous work in this field has overly relied on deep learning approaches suffering from the black-box problem, rendering them unable to articulate precisely what properties separate fake news from real news. This paper contributes to the limited work on interpretable fake news detection by engineering text-based features, applying statistical tests, and fitting and interpreting logistic regression models. The results of this paper support previous findings that fake and real news are best differentiated by metrics capturing complexity and style, that fake headlines communicate far more than real ones, and that text-based approaches can effectively discern between real and fake news

Global Tariffs and CO2

We study the impact of existing worldwide tariffs and several tariff reform schemes on global CO2 emissions using a multi-country, multi-sector general equilibrium model with detailed input-output linkages. Our analysis reveals the importance of a simple mechanism relating trade policy to global emissions that has not been previously highlighted in the literature: reducing existing tariffs tends to increase emissions primarily by increasing the global output of intermediate inputs relative to final goods. Greater use of intermediates implies, all things equal, more fossil fuel usage and therefore more emissions per unit of global final output. This effect ultimately results from the fact that tariffs are to some extent a tax on material but not on labor. This channel accounts for the majority of the emissions increase from moving to complete liberalization, exceeding even the mechanical effect of increased GDP and overwhelming effects from reallocation of activity across countries and sectors. We find that global partial liberalization schemes that temper this channel -- especially by reducing tariff escalation -- could achieve substantial global GDP increases with small increases in CO2 or even emissions reductions

PSYC 355/NEUR 355

Language is arguably the most powerful tool on the planet. Think of any product of human culture—all of it was influenced by language. This course asks four big questions about this unique device: What is language? Where did it come from? Is the brain designed for language? How does language affect thought? We will approach these questions from multiple perspectives, from linguistics to anthropology, neuroscience to philosophy and cognitive science to developmental psychology. In addition, you will become competent in the varied ways researchers attempt to answer these questions, with the ultimate goal of asking your own empirical questions about this distinctly human capacity

Participatory Culture and Collaborative Democracy: The Awesome Libraries Chapter

A brief overview of the Awesome Libraries Chapter of the Awesome Foundation and the process of crowdsourcing and funding transformative ideas in public libraries

Joachim du Bellay: France mère des arts, des armes et des lois

This essay discusses du Bellay\u27s poem, France mère des arts, focusing on the religious images created by the poetric voice, the reference to the story of Echo, and finally the reference to natural spaces and beings. Moreover, the essay studies these aspects in relation to French poetry written during the Renaissance, a body of work that is characterized by poetic lyricism and an unending desire to rediscover classical themes