San Francisco State University

About: San Francisco State University is a education organization based out in San Francisco, California, United States. It is known for research contribution in the topics: Population & Planet. The organization has 5669 authors who have published 11433 publications receiving 408075 citations. The organization is also known as: San Francisco State & San Francisco State Normal School.

Patterns and mechanisms of early Pliocene warmth

Abstract: About five to four million years ago, in the early Pliocene epoch, Earth had a warm, temperate climate. The gradual cooling that followed led to the establishment of modern temperature patterns, possibly in response to a decrease in atmospheric CO2 concentration, of the order of 100 parts per million, towards preindustrial values. Here we synthesize the available geochemical proxy records of sea surface temperature and show that, compared with that of today, the early Pliocene climate had substantially lower meridional and zonal temperature gradients but similar maximum ocean temperatures. Using an Earth system model, we show that none of the mechanisms currently proposed to explain Pliocene warmth can simultaneously reproduce all three crucial features. We suggest that a combination of several dynamical feedbacks underestimated in the models at present, such as those related to ocean mixing and cloud albedo, may have been responsible for these climate conditions.

Structure Matters: Twenty-One Teaching Strategies to Promote Student Engagement and Cultivate Classroom Equity.

Abstract: A host of simple teaching strategies—referred to as “equitable teaching strategies” and rooted in research on learning—can support biology instructors in striving for classroom equity and in teaching all their students, not just those who are already engaged, already participating, and perhaps already know the biology being taught.

Rapid and early export of Phaeocystis antarctica blooms in the Ross Sea, Antarctica

Abstract: The Southern Ocean is very important for the potential sequestration of carbon dioxide in the oceans1 and is expected to be vulnerable to changes in carbon export forced by anthropogenic climate warming2. Annual phytoplankton blooms in seasonal ice zones are highly productive and are thought to contribute significantly to pCO2 drawdown in the Southern Ocean. Diatoms are assumed to be the most important phytoplankton class with respect to export production in the Southern Ocean; however, the colonial prymnesiophyte Phaeocystis antarctica regularly forms huge blooms in seasonal ice zones and coastal Antarctic waters3. There is little evidence regarding the fate of carbon produced by P. antarctica in the Southern Ocean, although remineralization in the upper water column has been proposed to be the main pathway in polar waters4,5. Here we present evidence for early and rapid carbon export from P. antarctica blooms to deep water and sediments in the Ross Sea. Carbon sequestration from P. antarctica blooms may influence the carbon cycle in the Southern Ocean, especially if projected climatic changes lead to an alteration in the structure of the phytoplankton community6,7.

Retired A Stars and Their Companions: Exoplanets Orbiting Three Intermediate-Mass Subgiants

Abstract: We report precision Doppler measurements of three intermediate-mass subgiants obtained at Lick and Keck Observatories. All three stars show variability in their radial velocities consistent with planet-mass companions in Keplerian orbits. We find a planet with a minimum mass M_P sin i = 2.5 M_J in a 351.5 day orbit around HD 192699, a planet with a minimum mass of 2.0 M_J in a 341.1 day orbit around HD 210702, and a planet with a minimum mass of 0.61 M_J in a 297.3 day orbit around HD 175541. Mass estimates from stellar interior models indicate that all three stars were formerly A-type, main-sequence dwarfs with masses ranging from 1.65 to 1.85 M_☉. These three long-period planets would not have been detectable during their stars' main-sequence phases due to the large rotational velocities and stellar jitter exhibited by early-type dwarfs. There are now nine "retired" (evolved) A-type stars (M_* > 1.6 M_☉) with known planets. All nine planets orbit at distances ɑ ≥ 0.78 AU, which is significantly different from the semimajor axis distribution of planets around lower mass stars.

The Service Revolution

Abstract: Are we running out of physical-goods markets?The author shows how a large and growing market for commodities lies in the development of service systems.