The Initial Effects of Community Variables on Sand Prairie Restoration: Species Establishment and Community Responses

We established a sand prairie restoration experiment in northern Lower Michigan’s pine-oak barrens to analyze the effect of different community variables (vegetative cover, species richness, biomass, diversity, and floristic quality) when comparing: (1) how our restoration efforts (seeded treatments) compare to natural community succession (control plots), (2) how different seeding treatments affect these community variables, specifically when evaluating (2a) the effect of grass seeding densities; and (2b) the effect of different forb guilds (early flowering, late flowering, and legumes) during the initial two growing seasons of restoration establishment. In general, a comparison between seeded treatments and non-seeded control treatments indicates that our efforts may be more successful in the restoration of native sand prairie than would have resulted from succession alone. Restoration attempts displayed a significant decrease in invasive, resident species richness and increased diversity compared to succession. Treatments that included a high concentration of grass and/or an early season forb component had the greatest overall impact on plant community development. These treatments exhibited significantly higher plant biomass, diversity, and floristic quality than most other treatments. Conversely, these seeded treatments displayed less nonnative or invasive cover than other treatments. The benefit of high concentrations of grasses and early season forbs may play a critical role in initial species establishment of a sand prairie restoration due to the facilitative and competitive advantages they may provide in these harsh environments. However, it remains to be seen if these initially successful communities will have continued success over long periods of time

Enhanced BCS Superconductivity at a Corner

We consider the critical temperature for superconductivity, defined via the linear BCS equation. We prove that at weak coupling the critical temperature for a sample confined to a quadrant in two dimensions is strictly larger than the one for a half-space, which in turn is strictly larger than the one for $\mathbb{R}^2$. Furthermore, we prove that the relative difference of the critical temperatures vanishes in the weak coupling limit.Comment: 32 pages, 1 figur

BCS Critical Temperature on Half-Spaces

We study the BCS critical temperature on half-spaces in dimensions $d=1,2,3$ with Dirichlet or Neumann boundary conditions. We prove that the critical temperature on a half-space is strictly higher than on $\mathbb{R}^d$, at least at weak coupling in $d=1,2$ and weak coupling and small chemical potential in $d=3$. Furthermore, we show that the relative shift in critical temperature vanishes in the weak coupling limit.Comment: 62 pages, 5 figure

Whole body coordination and knee movement control during five rehabilitation exercises

Knee rehabilitation exercises to improve motor control, target movement fluency and displacement variability. Although knee movement in the frontal plane during exercise is routinely assessed in clinical practice, optimal knee control remains poorly understood. In this study, twenty-nine healthy participants (height: 1.73±0.11 m, mass: 73.5±16.4 kg, age: 28.0±6.9 years) performed four repetitions of five rehabilitation exercises whilst motion data were collected using the VICON PlugInGait full body marker set. Fluency and displacement variability were calculated for multiple landmarks, including Centre of Mass (CoM) and knee joint centres. Fluency was calculated as the inverse of the average number of times a landmark velocity in the frontal plane crossed zero. Variability was defined as the standard deviation of the frontal plane movement trajectories. CoM fluency and displacement variability were significantly different between tasks (p<0.001). CoM displacement variability was consistently smallest compared to the constituent landmarks (p<0.005). This was interpreted as a whole body strategy of compensatory variability constraining CoM frontal plane movement. Ipsilateral knee fluency (p<0.01) and displacement variability (p<0.001) differed substantially between tasks. The role of the weight-bearing knee seemed dependent on task constraints of the overall movement and balance, as well as constraints specific for knee joint stability

An efficient algorithm for critical circuits and finite eigenvectors in the max-plus algebra

AbstractWe consider the eigenvalue problem in the max-plus algebra for matrices in {−∞∪R}n×n but with eigenvectors in Rn. The problem is relaxed to a linear optimization (LO) problem of which the dual problem is solved by finding a maximal average weight circuit in the graph of the matrix. The Floyd–Warshall procedure is used to find such a circuit. This procedure also provides an efficient algorithm for finding an eigenvector

TB152: The Effect of Juvenile Wood on the Properties of Aspen Flakeboard

While the effects of juvenile wood tissue on solid wood products and paper have been known for some time, little information is available regarding its influence on structural flakeboard. Juvenile and mature wood tissue were identified b y their physical and mechanical properties in quaking aspen (Populus tremuloides Michx.). Sections of juvenile and mature wood were separated from 1-foot bolts of aspen. These sections were used to prepare three distinct types of structural flakeboard : juvenile wood-based, mature wood-based, and one formed from an equal mixture of the two. The panels were tested for selected mechanical and physical properties. The juvenile wood-based panels performed significantly better than the mature wood-based in respect to modulus of rupture, thickness swell, and water absorption, while also exhibiting somewhat higher values for modulus of elasticity, internal bond strength, compressive shear strength, and linear expansion. The panels made with a mixture of the two types of flakes did not display some of the poorer characteristics of the mature wood panels.https://digitalcommons.library.umaine.edu/aes_techbulletin/1052/thumbnail.jp

Two modes of vesicle recycling in the rat calyx of Held

Vesicle recycling was studied in the rat calyx of Held, a giant brainstem terminal involved in sound localization. Stimulation of brain slices containing the calyx-type synapse with a high extracellular potassium ion concentration in the presence of horseradish peroxidase resulted within several minutes in a reduction of the number of neurotransmitter vesicles and in the appearance of labeled endosome-like structures. After returning to normal solution, the endosome-like structures disappeared over a period of several minutes, whereas simultaneously the number of labeled vesicles increased. A comparison with afferent stimulation suggested that the endosome-like structures normally do not participate in the vesicle cycle. Afferent stimulation at 5 Hz resulted in sustained synaptic transmission, without vesicle depletion but with an estimated endocytotic activity of <0.2 synaptic vesicles per active zone per second. At 20 Hz, the presynaptic action potentials generally failed during prolonged stimulation. In identified synapses, the number of vesicles labeled by photoconversion after stimulation at 5 Hz in the presence of the styryl dye RH414 was much lower than the number of vesicles that were released, as determined by measuring EPSCs. No more than approximately 5% of the vesicles were labeled after 20 min stimulation at 5 Hz, whereas this stimulation protocol was sufficient to largely destain a terminal after previous loading. The results support a scheme for recycling in which two different modes coexist. At physiological demands, a pool of approximately 5% of all vesicles provides sufficient vesicles for release. During intense stimulation, such as occurs in the presence of high extracellular K+, the synapse resorts to bulk endocytosis, a very slow mode of recycling

Long-Term Outcome of an HIV-Treatment Programme in Rural Africa: Viral Suppression despite Early Mortality

Objective. To define the long-term (2–4 years) clinical and virological outcome of an antiretroviral treatment (ART) programme in rural South Africa. Methods. We performed a retrospective observational cohort study, including 735 patients who initiated ART. Biannual monitoring, including HIV-RNA testing, was performed. Primary endpoint was patient retention; virological suppression (HIV-RNA < 50 copies/mL) and failure (HIV-RNA > 1000 copies/mL) were secondary endpoints. Moreover, possible predictors of treatment failure were analyzed. Results. 63% of patients (466/735) have a fully suppressed HIV-RNA, a median of three years after treatment initiation. Early mortality was high: 14% died within 3 months after treatment start. 16% of patients experienced virological failure, but only 4% was switched to second-line ART. Male gender and a low performance score were associated with treatment failure; immunological failure was a poor predictor of virological failure. Conclusions. An “all or nothing” phenomenon was observed in this rural South African ART programme: high early attrition, but good virological control in those remaining in care. Continued efforts are needed to enrol patients earlier. Furthermore, the observed viro-immunological dissociation emphasises the need to make HIV-RNA testing more widely available