Isometric immersions, energy minimization and self-similar buckling in non-Euclidean elastic sheets

The edges of torn plastic sheets and growing leaves often display hierarchical buckling patterns. We show that this complex morphology (i) emerges even in zero strain configurations, and (ii) is driven by a competition between the two principal curvatures, rather than between bending and stretching. We identify the key role of branch-point (or "monkey-saddle") singularities in generating complex wrinkling patterns in isometric immersions, and show how they arise naturally from minimizing the elastic energy.Comment: 6 pages, 6 figures. This article supersedes arXiv:1504.0073

EC86-1862 Nebraska Commercial Turfgrass Disease Control Guide For Profession Turfgrass Managers

This extension circular contains four-color photos to help professional turfgrass managers identify the different turfgrass diseases in Nebraska. Tables are included that describe the disease, the common name of fungicides, trade names, and descriptions of how to control these diseases

EC86-1862 Nebraska Commercial Turfgrass Disease Control Guide For Profession Turfgrass Managers

This extension circular contains four-color photos to help professional turfgrass managers identify the different turfgrass diseases in Nebraska. Tables are included that describe the disease, the common name of fungicides, trade names, and descriptions of how to control these diseases

Nature's forms are frilly, flexible, and functional

A ubiquitous motif in nature is the self-similar hierarchical buckling of a thin lamina near its margins. This is seen in leaves, flowers, fungi, corals and marine invertebrates. We investigate this morphology from the perspective of non-Euclidean plate theory. We identify a novel type of defect, a branch-point of the normal map, that allows for the generation of such complex wrinkling patterns in thin elastic hyperbolic surfaces, even in the absence of stretching. We argue that branch points are the natural defects in hyperbolic sheets, they carry a topological charge which gives them a degree of robustness, and they can influence the overall morphology of a hyperbolic surface without concentrating elastic energy. We develop a theory for branch points and investigate their role in determining the mechanical response of hyperbolic sheets to weak external forces. We also develop a discrete differential geometric (DDG) framework for applications to the continuum mechanics of hyperbolic elastic sheets.Comment: 35 pages, 26 figure

Just for Me Engagement

BACKGROUND The Mathematics Education Support Hub (MESH) at UWS is a unit within the learning and teaching portfolio with a remit to provide mathematical and statistical help to all students within the university. One method of enabling this support has been a mathematics library roving program, introduced in 2013 to complement literacy support which was already operating in the library. AIMS The program aims to provide “just in time” support for students experiencing difficulty with the mathematical and statistical components of their subjects in a non-confrontational environment. A secondary aim is to increase student confidence in their own mathematical abilities. DESCRIPTION OF INTERVENTION The MESH library roving program began in the Autumn session 2013 and has continued during Spring 2013 and Autumn 2014. Support is provided by MESH staff who ‘rove’ the various campus libraries for two hour sessions at well-advertised times throughout the teaching and study vacation periods of the semester. These library rovers assist individual students and groups by encouraging students to engage with the mathematical and statistical content of their subject through a process of guided discovery of the material as well as direct responses to enquiries. The time taken for such interventions range from a few minutes to approximately half an hour, with students with problems requiring longer discussion usually referred back to subject teaching teams for further clarification. Students availing themselves of the service range from first year to post graduate with problems coming from subjects as diverse as business, finance, biomechanics, law and engineering as well as mathematics and statistics subjects. DESIGN AND METHODS Each library consultation is recorded on an electronic form and features of the consultation are noted. The data collected includes the campus, number of students in a group, student year of study, length of time spent with the group, unit or discipline area in which assistance is provided as well as if a group or student has been seen previously. At the end of 2013 a research project conducted in conjunction with the academic literacy library roving program collected survey responses from students, library staff and rovers. Analysis of this data along with surveys of students, library staff and rovers will show the patterns of use and responses of various stakeholders to the program. RESULTS The data collected for this project are still being processed and it is anticipated features of the analysis will be presented. It is envisaged that models of student behaviour gleaned from this analysis will form the basis of the results. The nature of requests from students and how these are dealt with by the rovers will also be presented. Responses from student, librarian and rover surveys will also provide an indication of student engagement with the service. CONCLUSIONS The intention of this project is to use the results to fine tune the impact and delivery of the library roving program

Tertiary students’ engagement in a mathematics support program

Background Mathematics is often perceived to be a difficult subject and students struggle with it. A combination of factors including a compromise with tertiary admission requirements, such as prerequisites, a link between Federal funding and student number at an institution, relaxed mathematics requirement to complete secondary education, ATAR based admission to programs, and, admission of mature age and international students with diverse backgrounds elevates the number of tertiary students struggling with mathematics. At UWS, to support these students with their mathematics, various services including lecturer consultation time, tutorials, pre- and within-semester workshops, library roving, online tutoring, peer-assisted student support and free internet sites are made available to them. This study deals with students’ engagement in pre-semester workshops. Aims The aim of this study was to evaluate (i) age and gender based influences on students’ engagement in the workshops, (ii) perceived reasons to participate in the workshops and (iii) post-workshops perceptions of their mathematical competency. Methodology The workshops were advertised on the UWS web and emails were sent to the prospective students to encourage them to register for these voluntary workshops. The workshops aimed to revise basics of algebra, trigonometry, calculus and statistics to prepare students for their first year mathematics units. The students attended 1 – 3 days workshops in these areas before starting degree programs at UWS. The students were asked to complete two surveys one each on their first- and last-day of the program, and, pre- and post-achievement tests. The first- and last-day survey targeted students’ reasons to participate in and satisfaction from attending the workshops respectively. Only 57.3% of those who completed first day survey (616) from 2011 to 2014 completed the last-day survey. The data were analysed to evaluate areas of interest specified under aims. Results The results of the study revealed that students’ intention to engage and actual engagement in the workshops were significantly different. The participation was significantly higher of male (62.1%) than female (37.9%) students and 33.5% of them were older than 20 years indicating a high percentage of matured age students. The major reason for participation in the workshops was their perceived weak or very weak background in these areas. The number of weak or very weak students in calculus and statistics was higher than algebra and trigonometry. Analysis of post-workshops survey revealed a significant improvement in their perceived knowledge of these mathematics areas. This claim was partly supported by significantly improved post-test scores in 2014. Gender, age and year to year based trends in these findings will also be discussed. Conclusions and Future Directions Students perceived their engagement in pre-semester workshops was helpful in improving their desired mathematics content knowledge. Further research to investigate students’ performance in their required mathematics subjects and programs is warranted

Health information system strengthening and malaria elimination in Papua New Guinea

Background The objective of the study was to describe an m-health initiative to strengthen malaria surveillance in a 184-health facility, multi-province, project aimed at strengthening the National Health Information System (NHIS) in a country with fragmented malaria surveillance, striving towards enhanced control, pre-elimination. Methods A remote-loading mobile application and secure online platform for health professionals was created to interface with the new system (eNHIS). A case-based malaria testing register was developed and integrated geo-coded households, villages and health facilities. A malaria programme management dashboard was created, with village-level malaria mapping tools, and statistical algorithms to identify malaria outbreaks. Results Since its inception in 2015, 160,750 malaria testing records, including village of residence, have been reported to the eNHIS. These case-based, geo-coded malaria data are 100% complete, with a median data entry delay of 9 days from the date of testing. The system maps malaria to the village level in near real-time as well as the availability of treatment and diagnostics to health facility level. Data aggregation, analysis, outbreak detection, and reporting are automated. Conclusions The study demonstrates that using mobile technologies and GIS in the capture and reporting of NHIS data in Papua New Guinea provides timely, high quality, geo-coded, case-based malaria data required for malaria elimination. The health systems strengthening approach of integrating malaria information management into the eNHIS optimizes sustainability and provides enormous flexibility to cater for future malaria programme needs.The Asian Development Bank coordinated the international tender for this pilo

BACE1 activity impairs neuronal glucose oxidation:rescue by beta-hydroxybutyrate and lipoic acid

Glucose hypometabolism and impaired mitochondrial function in neurons have been suggested to play early and perhaps causative roles in Alzheimer's disease (AD) pathogenesis. Activity of the aspartic acid protease, beta-site amyloid precursor protein (APP) cleaving enzyme 1 (BACE1), responsible for beta amyloid peptide generation, has recently been demonstrated to modify glucose metabolism. We therefore examined, using a human neuroblastoma (SH-SY5Y) cell line, whether increased BACE1 activity is responsible for a reduction in cellular glucose metabolism. Overexpression of active BACE1, but not a protease-dead mutant BACE1, protein in SH-SY5Y cells reduced glucose oxidation and the basal oxygen consumption rate, which was associated with a compensatory increase in glycolysis. Increased BACE1 activity had no effect on the mitochondrial electron transfer process but was found to diminish substrate delivery to the mitochondria by inhibition of key mitochondrial decarboxylation reaction enzymes. This BACE1 activity-dependent deficit in glucose oxidation was alleviated by the presence of beta hydroxybutyrate or α-lipoic acid. Consequently our data indicate that raised cellular BACE1 activity drives reduced glucose oxidation in a human neuronal cell line through impairments in the activity of specific tricarboxylic acid cycle enzymes. Because this bioenergetic deficit is recoverable by neutraceutical compounds we suggest that such agents, perhaps in conjunction with BACE1 inhibitors, may be an effective therapeutic strategy in the early-stage management or treatment of AD

Barotropic tides on the southeast New England shelf : a view from a hybrid data assimilative modeling approach

Author Posting. © American Geophysical Union, 2006. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 111 (2006): C08002, doi:10.1029/2005JC003254.A high-resolution hybrid data assimilative (DA) modeling system is used to study barotropic tides and tidal dynamics on the southeast New England shelf. In situ observations include tidal harmonics of 5 major tidal constituents [M2, S2, N2, O1, and K1] analyzed from coastal sea level and bottom pressure gauges. The DA system consists of both forward and inverse models. The former is the three-dimensional, finite difference, nonlinear Regional Ocean Modeling System (ROMS). The latter is a three-dimensional linearized, frequency domain, finite element model TRUXTON. The DA system assimilates in situ observations via the inversion for the barotropic tidal open boundary conditions (OBCs). Model skill is evaluated by comparing the misfits between the observed and modeled tidal harmonics. The assimilation scheme is found effective and efficient in correcting the tidal OBCs, which in turn improve ROMS tidal solutions. Up to 50% decreases of model/data misfits are achieved after inverse data assimilation. Co-amplitude and co-phase maps and tidal current ellipses for each of 5 tidal constituents are generated, revealing complex tidal variability in this transition region between the tidally amplified Gulf of Maine in the northeast and the tidally much less energetic Middle Atlantic Bight in the southwest. Detailed examinations on the residual circulation, energetics, and momentum balances of the M2 tide reveal the key roles of the unique bottom bathymetry of Nantucket Shoals and the complex coastal geometry in affecting the regional tidal dynamics.This work was supported by WHOI Coastal Ocean Institute Research Award. J.W. acknowledges support of the Office of Naval Research