Convergence rates of the DPG method with reduced test space degree

This paper presents a duality theorem of the Aubin-Nitsche type for discontinuous Petrov Galerkin (DPG) methods. This explains the numerically observed higher convergence rates in weaker norms. Considering the specific example of the mild-weak (or primal) DPG method for the Laplace equation, two further results are obtained. First, the DPG method continues to be solvable even when the test space degree is reduced, provided it is odd. Second, a non-conforming method of analysis is developed to explain the numerically observed convergence rates for a test space of reduced degree

Wave attenuation at a salt marsh margin: A case study of an exposed coast on the Yangtze estuary

To quantify wave attenuation by (introduced) Spartina alterniflora vegetation at an exposed macrotidal coast in the Yangtze Estuary, China, wave parameters and water depth were measured during 13 consecutive tides at nine locations ranging from 10 m seaward to 50 m landward of the low marsh edge. During this period, the incident wave height ranged from <0.1 to 1.5 m, the maximum of which is much higher than observed in other marsh areas around the world. Our measurements and calculations showed that the wave attenuation rate per unit distance was 1 to 2 magnitudes higher over the marsh than over an adjacent mudflat. Although the elevation gradient of the marsh margin was significantly higher than that of the adjacent mudflat, more than 80% of wave attenuation was ascribed to the presence of vegetation, suggesting that shoaling effects were of minor importance. On average, waves reaching the marsh were eliminated over a distance of similar to 80 m, although a marsh distance of >= 100 m was needed before the maximum height waves were fully attenuated during high tides. These attenuation distances were longer than those previously found in American salt marshes, mainly due to the macrotidal and exposed conditions at the present site. The ratio of water depth to plant height showed an inverse correlation with wave attenuation rate, indicating that plant height is a crucial factor determining the efficiency of wave attenuation. Consequently, the tall shoots of the introduced S. alterniflora makes this species much more efficient at attenuating waves than the shorter, native pioneer species in the Yangtze Estuary, and should therefore be considered as a factor in coastal management during the present era of sea-level rise and global change. We also found that wave attenuation across the salt marsh can be predicted using published models when a suitable coefficient is incorporated to account for drag, which varies in place and time due to differences in plant characteristics and abiotic conditions (i.e., bed gradient, initial water depth, and wave action).

“You Want Me to Come to Your Office?!”: Student experiences of Moving from Failure to Success in a Nursing Course

The experiences of undergraduate nursing students facing and overcoming failure in their coursework must be understood in order for nurse educators to effectively engage and provide supportive strategies to their students. A student-centred learning perspective and interpretive phenomenological approach to research frames this study of ten students’ accounts of their experiences from failure to success in a second year nursing course. Central themes include: Feeling Uncomfortable, Finding Confidence, and Cultivating a New Identity. Seeking feedback and building study habits and central to the students\u27 pursuit of confidence and new identity formation. Implications for nurse educators’ proactive engagement with students identified as being ‘at risk’ are discussed and strategies proposed. Individualized, student-centred, and focused feedback forged from trusted student-instructor relationships appear to be central strategies to assist the transition between failure and success. Résumé La compréhension des expériences des étudiants en sciences infirmières de premier cycle qui ont été confrontées à un échec dans un cours et qui l’ont surmonté permettrait aux infirmières enseignantes de soutenir efficacement et de fournir des stratégies d’apprentissage à leurs étudiantes. Développée selon une perspective d’apprentissage centrée sur l’étudiante et menée grâce à une approche de recherche phénoménologique interprétative, cette étude porte sur le récit de dix étudiantes de deuxième année en sciences infirmières de leurs expériences d’échec puis de réussite d’un cours. Les thèmes centraux suivants ont été identifiés: se sentir mal à l\u27aise, trouver la confiance en soi et cultiver une nouvelle identité. Chercher à obtenir de la rétroaction et construire des habitudes d’études sont au cœur de la quête des étudiantes d’une confiance en soi et d’une formation d’une nouvelle identité. Les implications pour un engagement proactif des infirmières enseignantes auprès des étudiantes considérées comme étant « à risque » sont discutées et des stratégies sont proposées. Basée sur la relation de confiance entre l’étudiante et l’enseignante, la rétroaction ciblée, personnalisée et centrée sur l’étudiante est au cœur des stratégies essentielles pour faciliter la transition entre l’échec et la réussite

Cross-shore gradients of physical disturbance in mangroves: Implications for seedling establishment

10.5194/bg-10-5411-2013Biogeosciences1085411-541