Natural Sciences

In nature, it is common to see seasonal changes in animal morphology and behavior. For example, squirrels and bears hibernate in winter; many birds migrate seasonally; and a wide range of animals from frogs to sheep mate and reproduce only during a fixed breeding season. These seasonal rhythms are adaptations of the animals to seasonally changing environment and are vital for animal survival.

Cancer develops when evolutionary forces act on mutated cells. When mutations and natural selection repeat over time, cancerous cell populations grow and spread. The resulting cancer cell population displays extensive genetic and functional heterogeneity within and across tumors. This diversity presents challenges to our understanding of tumor biology and ability to treat cancer, especially because the evolutionary dynamics and variables underlying the heterogeneity are often poorly understood.

Recent biological and biomedical research, especially work on the microbiome, has revived the idea that living things are not “individuals”, but rather collectives. The aim of this interdisciplinary project is to offer a philosophical and scientific examination of the conditions under which something can be said to be an “individual” in the living world – and how, in certain circumstances, individuals function as a single collective, while collectives can function as biological individuals.

California’s mining and industrial history have led to an excessive build-up of mercury in the Bay Area. As one of the top ten pollutants of the world, this toxic heavy metal has troubling implications for human and environmental health. Although mercury is relatively well studied in aquatic ecosystems, less work has focused on terrestrial animals. However, we know that soil organisms, such as earthworms, accumulate mercury by consuming decaying plant and animal materials in the ground.

Large variations in seasonal temperature and rainfall threaten crop production, food prices, and food security at local to global scales. This project focuses on the impacts of climate variability on Europe’s agricultural regions, with an emphasis on wheat in France. Although France has a relatively small agricultural area, it has among the highest wheat yields in the world. Climateinduced shocks to crop production thus influence global prices for wheat and other commodities linked to wheat through markets.

The goal of the Stanford Solar Observatories Group is to study the origin of solar variability, characterize and understand the Sun's interior and the various components of magnetic activity. To achieve this goal, data analysis is performed from space missions. For a better understanding of the Sun and predictive capabilities for solar activity and space weather, these observations have to be accompanied by realistic numerical simulations of the subsurface flows and magnetic structures of the Sun.

In developed countries about 80% of the total population suffers from acute and 5–10% from permanent lower back pain (LBP). An early diagnosis is crucial to reduce patient suffering and lower the economic burden on the society. In a representative study for the western world, the cost of LBP in Switzerland was estimated at 2.6 billion Euros in 2005. Nevertheless, surprisingly little is known about geometrical abnormalities resulting in LBP. This is in part due to the subtle distinction between healthy geometrical variability and pathological abnormal deformities of the spine.

Symbiosis is a close interaction between different species. The bacteria Wolbachia is the most common endosymbiont (a symbiont living within host cells) described to date. In mosquitoes, Wolbachia induces a form of sterility in crosses between males and females infected with distinct Wolbachia types. This feature makes Wolbachia infection a promising non-chemical tool to reduce human diseases transmitted by mosquitoes. However, the molecular basis of the Wolbachia-induced sterility is still unknown.