Hydrogen-induced changes in the breakdown voltage of InP HEMTs

In this work, electrical measurements show that the breakdown voltage,BVDG, of InP HEMTs increases following exposure to H2. This BVDG shift is nonrecoverable. The increase in BVDG is found to be due to a decrease in the carrier concentration in the extrinsic portion of the device.We provide evidence that H2 reacts with the exposed InAlAs surface in the extrinsic region next to the gate, changing the underlying carrier concentration. Hall measurements of capped and uncapped HEMT samples show that the decrease in sheet carrier concentration can be attributed to a modification of the exposed InAlAs surface. Consistent with this, XPS experiments on uncapped heterostructures give evidence of As loss from the InAlAs surface upon exposure to hydrogen.

Single beam survey data and links to sea-bottom video files off Helgoland

Kelp forests represent a major habitat type in coastal waters worldwide and their structure and distribution is predicted to change due to global warming. Despite their ecological and economical importance, there is still a lack of reliable spatial information on their abundance and distribution. In recent years, various hydroacoustic mapping techniques for sublittoral environments evolved. However, in turbid coastal waters, such as off the island of Helgoland (Germany, North Sea), the kelp vegetation is present in shallow water depths normally excluded from hydroacoustic surveys. In this study, single beam survey data consisting of the two seafloor parameters roughness and hardness were obtained with RoxAnn from water depth between 2 and 18 m. Our primary aim was to reliably detect the kelp forest habitat with different densities and distinguish it from other vegetated zones. Five habitat classes were identified using underwater-video and were applied for classification of acoustic signatures. Subsequently, spatial prediction maps were produced via two classification approaches: Linear discriminant analysis (LDA) and manual classification routine (MC). LDA was able to distinguish dense kelp forest from other habitats (i.e. mixed seaweed vegetation, sand, and barren bedrock), but no variances in kelp density. In contrast, MC also provided information on medium dense kelp distribution which is characterized by intermediate roughness and hardness values evoked by reduced kelp abundances. The prediction maps reach accordance levels of 62% (LDA) and 68% (MC). The presence of vegetation (kelp and mixed seaweed vegetation) was determined with higher prediction abilities of 75% (LDA) and 76% (MC). Since the different habitat classes reveal acoustic signatures that strongly overlap, the manual classification method was more appropriate for separating different kelp forest densities and low-lying vegetation. It became evident that the occurrence of kelp in this area is not simply linked to water depth. Moreover, this study shows that the two seafloor parameters collected with RoxAnn are suitable indicators for the discrimination of different densely vegetated seafloor habitats in shallow environments.

1998/1999 UM Women's Basketball Team

Back Row: manager Stephanie Van Eyk, student trainer Jennifer Rasmussen, trainer Roxann Dahl, Ruth Kipping, Raina Goodlow, Mandy Stowe, head coach Sue Guevara, Katie Dykhouse, Alison Miller, Heather Oesterle, manager James Sanders, manager Yulonda Cole, manager Robyn Scherr

Front Row: ass't coach Eileen Shea, vol. ass't coach Molly Murray, Alayne Ingram, Kenisha Walker, Ann Lemire, Stacey Thomas, Anne Thorius, ass't coach Yulonda Wimbish, ass't coach Yvette Harris

1999/2000 UM Women's Basketball Team

Back Row: ass't coach Yvette Harris, ass't coach Eileen Shea, Alayne Ingram, Infini Robinson, Susana Jara, Ruth Kipping, LeeAnn Bies, Raina Goodlow, Heather Oesterle, manager James Sanders, ass't coach Yulonda Wimbish-Gay, head coach Sue Guevara

Front Row: manager Yolanda Cole, trainer Roxann Dahl, co-captain Anne Thorius, Alison Miller, co-captain Stacey Thomas, Kenisha Walker, Katie Dykhouse, student trainer Jamie Corl, manager Stephanie Van Eyk

2000/2001 UM Women's Basketball Team

Back Row: ass't coach Ron Mott, ass't coach Yvette Harris, Cathy Speck, Leeann Bies, Jennifer Smith, Raina Goodlow, Christie Schumacher, James Sanders, dir. basketball operations Yulonda Wimbish-Gay, ass't coach Eileen Shea

Middle Row: trainer Roxann Dahl, manager Joy Huntington, Infini Robinson, Stephanie Gandy, Alayne Ingram, Michaela Leary, Susan Jara, Heather Oesterle, head coach Sue Guevara

Front Row: Anne Thorius, Katie Dykhouse

2001/2002 UM Women's Basketball Team

Back Row: head coach Sue Guevara, assistant head coach Angela Jackson, Tabitha Pool, BreAnne McPilamy, Katrina Mason, Jennifer Smith, LeeAnn Bies, Stephanie Gandy, Sierra Hauser-Price, assistant coach Eileen Shea-Hilliard, assistant coach Ron Mott,

director of basketball operations Molly Murray, trainer Roxann Dahl, Alayne Ingram, Heather Oesterle, Raina Goodlow, Susana Jara, manager Stacey Lerchenfeld, student trainer Beth Chase