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ABSTRACT The marine microalgaEmiliania huxleyiis widely distributed in the surface oceans and is prone to infection by coccolithoviruses that can terminate its blooms. However, little is known about how global change factors like solar UV radiation (UVR) and ocean warming affect the host‐virus interaction. We grew the microalga at 2 temperature levels with or without the virus in the presence or absence of UVR and investigated the physiological and transcriptional responses. We showed that viral infection noticeably reduced photosynthesis and growth of the alga but was less harmful to its physiology under conditions where UVR influenced viral DNA expression. In the virus‐infected cells, the combination of UVR and warming (+4°C) led to a 13‐fold increase in photosynthetic carbon fixation rate, with warming alone contributing a change of about 5–7‐fold. This was attributed to upregulated expression of genes related to carboxylation and light‐harvesting proteins under the influence of UVR, and to warming‐reduced infectivity. In the absence of UVR, viral infection downregulated the metabolic pathways of photosynthesis and fatty acid degradation. Our results suggest that solar UV exposure in a warming ocean can reduce the severity of viral attack on this ecologically important microalga, potentially prolonging its blooms. 

Transfer stigma refers to a type of stigma associated with students’ transfer status and/or their community college background. It plays a significant role in post-transfer adjustment and may negatively impact post-transfer outcomes such as retention and obtaining a baccalaureate degree. This study focused on quantitatively measuring transfer stigma among transfer students attending a four-year institution. Drawing from previous studies, we developed a 13-item transfer stigma measure and included it in a transfer student survey. The survey data was collected from 450 current transfer students at a public, flagship four-year university in Louisiana. Through an exploratory factor analysis and a confirmatory factor analysis, we revealed a four-factor structure of transfer stigma measures: internalized self-stigma, perceptions about community colleges, lack of support, and perceived judgment. Subsequent statistical analyses examined group differences in the degree of transfer stigma across various transfer student subgroups defined by transfer type, gender, race/ethnicity, age, and major. 

In the modern ocean, the transformation of light surface waters to dense deep waters primarily occurs in the Atlantic basin rather than in the North Pacific or Southern Oceans. The reasons for this remain unclear, as both models and paleoclimatic observations suggest that sinking can sometimes occur in the Pacific. We present a six-box model of overturning that combines insights from a number of previous studies. A key determinant of the overturning configuration in our model is whether the Antarctic Intermediate Waters are denser than the northern subpolar waters, something that depends on the magnitude and configuration of atmospheric freshwater transport. For the modern ocean, we find that although the interbasin atmospheric freshwater flux suppresses Pacific sinking, the poleward atmospheric freshwater flux out of the subtropics enhances it. When atmospheric temperatures are held fixed, North Pacific overturning can strengthen with either increases or decreases in the hydrological cycle, as well as under reversal of the interbasin freshwater flux. Tipping-point behavior, where small changes in the hydrological cycle may cause the dominant location of densification of light waters to switch between basins and the magnitude of overturning within a basin to exhibit large jumps, is seen in both transient and equilibrium states. This behavior is modulated by parameters such as the poorly constrained lateral diffusive mixing coefficient. If hydrological cycle amplitude is varied consistently with global temperature, northern polar amplification is necessary for the Atlantic overturning to collapse. Certain qualitative insights incorporated in the model can be validated using a fully coupled climate model. Significance StatementCurrently, the global overturning circulation involves the conversion of waters lighter than Antarctic Intermediate Water to deep waters denser than Antarctic Intermediate Water primarily in the North Atlantic, rather than in the North Pacific or Southern Oceans. Many different factors have been invoked to explain this configuration, with atmospheric freshwater transport, basin geometry, lateral mixing, and Southern Ocean winds playing major roles. This paper develops a simple theory that combines previous theories, presents the intriguing idea that alternate configurations might be possible, and identifies multiple possible tipping points between these states.