Transplantation of pancreatic progenitors or insulin-secreting cells derived from human embryonic stem cells (hESCs) has been proposed as a therapy for diabetes. We describe a seven-stage protocol that efficiently converts hESCs into insulin-producing cells. Stage (S) 7 cells expressed key markers of mature pancreatic beta cells, including MAFA, and displayed glucose-stimulated insulin secretion similar to that of human islets during static incubations in vitro. Additional characterization using single-cell imaging and dynamic glucose stimulation assays revealed similarities but also notable differences between S7 insulin-secreting cells and primary human beta cells. Nevertheless, S7 cells rapidly reversed diabetes in mice within 40 days, roughly four times faster than pancreatic progenitors. Therefore, although S7 cells are not fully equivalent to mature beta cells, their capacity for glucose-responsive insulin secretion and rapid reversal of diabetes in vivo makes them a promising alternative to pancreatic progenitor cells or cadaveric islets for the treatment of diabetes.

Silicic volcanic eruptions pose considerable hazards, yet the processes leading to these eruptions remain poorly known. A missing link is knowledge of the thermal history of magma feeding such eruptions, which largely controls crystallinity and therefore eruptability. We have determined the thermal history of individual zircon crystals from an eruption of the Taupo Volcanic Zone, New Zealand. Results show that although zircons resided in the magmatic system for 10 to 10 years, they experienced temperatures >650° to 750°C for only years to centuries. This implies near-solidus long-term crystal storage, punctuated by rapid heating and cooling. Reconciling these data with existing models of magma storage requires considering multiple small intrusions and multiple spatial scales, and our approach can help to quantify heat input to and output from magma reservoirs.

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C oo pe ra tive learning is an instr uc tio nal format in whi ch students work togeth er in small, structured, h eterogeneous groups to mast er th e co n te nt of th e lesso n . Students are responsible not only for learning th e material, but also for helping th ei r group-mat es learn. With cooperative learning, students can imp rove motor skills, develop sacial skills, wo rk together as a team, help others improve skills, take responsibility for th ei r own learning, learn to give and receive feedback , and develop respo nsibility (Dyson, 200 1).For th e last four yea rs, Allison Ru bin , an e le me nt a ry school teacher, has implemented coo pe ra tive learning in he r physical ed ucatio n program at Moh arimet Elemen tary chool in Madbury, ew Hampshire. Ben Dyson , a un ive rsity professor, has a ided thi s process with th e assista nce of studentteach er interns. The intention of thi s article is to present physical ed ucato rs with ideas o n how to implement cooperative learning. The article offers a bri efbackground of coo pe ra tive-lea rning eleme nts, discu sses th e implementation ofcooperative learning, provid es an example of a coo pe rative-lea rn ing unit, and highlights str uggles and co ncerns associated with changes in th e curriculum and instruction that result from using co o pe ra tive learning.

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