NASA oceanic processes program

Current flight projects and definition studies, brief descriptions of individual research activities, and bibliography of referred journal articles are provided

On the Optimization of Mixture Resolving Signal Processing Structures

Mixture resolving signal processing optimization with optimum linear detection operators and mixture resolving estimator

Stable Marriage with Ties and Bounded Length Preference Lists

We consider variants of the classical stable marriage problem in which preference lists may contain ties, and may be of bounded length. Such restrictions arise naturally in practical applications, such as centralised matching schemes that assign graduating medical students to their first hospital posts. In such a setting, weak stability is the most common solution concept, and it is known that weakly stable matchings can have different sizes. This motivates the problem of finding a maximum cardinality weakly stable matching, which is known to be NP-hard in general. We show that this problem is solvable in polynomial time if each man's list is of length at most 2 (even for women's lists that are of unbounded length). However if each man's list is of length at most 3, we show that the problem becomes NP-hard and not approximable within some d > 1, even if each woman's list is of length at most 4

Untethered Learning: A Mixed Methods Study of Mobilized Adventure Learning

textMobile technologies now afford unprecedented opportunities, resources, and possibilities for learning. Among them, is the opportunity for students to engage in hands-on, out-of-classroom learning activities such as Adventure Learning. Since 2007, Adventure Learning has developed as an educational framework for using information and communication technologies to connect learners with expeditionary teams where video-based communication provides a sense of adventure for learners. The study was conducted in a public high school where an Environmental Science teacher used mobile learning technologies to create Adventure Learning projects where students participated both fin the classroom and as members of an “expeditionary team.” It was also intended to examine both the benefits and challenges in implementing ubiquitous mobile technologies in the field, combined with the use of student-centered pedagogies in their classrooms. The major questions of the study asked how did a teacher leverage mobilized Adventure Learning to design learning activities? And how did active participation in a mobilized Adventure Learning project affect student interest in the subject of Environmental Science? The study involved examining the ways the teacher leveraged the affordances of mobile technologies to create a hands-on, collaborative, and Adventure Learning environments outside of the classroom. The hands-on learning activities were designed to enable students to gather first-hand information related to environmental science. Subjects in the study included a high school Environmental Science teacher along with 104 participating students. Using a mixed methods approach, qualitative data were gathered through observations of learning activities, interviews and focus groups and artifacts. Quantitative data were gathered through surveys administered to the students before and after the treatment. The results indicated that, contrary to the teacher’s expectations, students indicated a preference for learning through book and lecture rather than hands-on discovery of information in both pre and post treatment surveys. Results of the study also demonstrated differences in learning preference relating to percentage of students participating in field-based, hands-on learning activities or in lecture-book classroom learning activities. Recommendations for future research and for educational practice are offered. Limitations of the study include the small sample size and short time duration of the study.Curriculum and Instructio

The Effects of Climate Variability on Phytoplankton Composition in the Equatorial Pacific Ocean using a Model and a Satellite-Derived Approach

Compared the interannual variation in diatoms, cyanobacteria, coccolithophores and chlorophytes from the NASA Ocean Biogeochemical Model with those derived from satellite data (Hirata et al. 2011) between 1998 and 2006 in the Equatorial Pacific. Using NOBM, La Ni a events were characterized by an increase in diatoms (correlation with MEI, r=-0.81, P<0.05), while cyanobacteria concentrations decreased significantly (r=0.61; P<0.05). El Nino produced the reverse pattern, with cyanobacteria populations increasing while diatoms plummeted. This represented a radical shift in the phytoplankton community in response to climate variability. However, satellite-derived phytoplankton groups were all negatively correlated with climate variability (r ranged from -0.39 for diatoms to -0.64 for coccolithophores, P<0.05). Spatially, the satellite-derived approach was closer to an independent in situ dataset for all phytoplankton groups except diatoms than NOBM. However, the different responses of phytoplankton to intense interannual events in the Equatorial Pacific raises questions about the representation of phytoplankton dynamics in models and algorithms: is a phytoplankton community shift as in the model or an across-the-board change in abundances of all phytoplankton as in the satellite-derived approach