Mathematical modelling of tissue-engineering angiogenesis

We present a mathematical model for the vascularisation of a porous scaffold following implantation in vivo. The model is given as a set of coupled non-linear ordinary differential equations (ODEs) which describe the evolution in time of the amounts of the different tissue constituents inside the scaffold. Bifurcation analyses reveal how the extent of scaffold vascularisation changes as a function of the parameter values. For example, it is shown how the loss of seeded cells arising from slow infiltration of vascular tissue can be overcome using a prevascularisation strategy consisting of seeding the scaffold with vascular cells. Using certain assumptions it is shown how the system can be simplified to one which is partially tractable and for which some analysis is given. Limited comparison is also given of the model solutions with experimental data from the chick chorioallantoic membrane (CAM) assay

Correlation between microstructure and magnetotransport in organic semiconductor spin valve structures

We have studied magnetotransport in organic-inorganic hybrid multilayer junctions. In these devices, the organic semiconductor (OSC) Alq$_3$ (tris(8-hydroxyquinoline) aluminum) formed a spacer layer between ferromagnetic (FM) Co and Fe layers. The thickness of the Alq$_3$ layer was in the range of 50-150 nm. Positive magnetoresistance (MR) was observed at 4.2 K in a current perpendicular to plane geometry, and these effects persisted up to room temperature. The devices' microstructure was studied by X-ray reflectometry, Auger electron spectroscopy and polarized neutron reflectometry (PNR). The films show well-defined layers with modest average chemical roughness (3-5 nm) at the interface between the Alq$_3$ and the surrounding FM layers. Reflectometry shows that larger MR effects are associated with smaller FM/Alq$_3$ interface width (both chemical and magnetic) and a magnetically dead layer at the Alq$_3$/Fe interface. The PNR data also show that the Co layer, which was deposited on top of the Alq$_3$, adopts a multi-domain magnetic structure at low field and a perfect anti-parallel state is not obtained. The origins of the observed MR are discussed and attributed to spin coherent transport. A lower bound for the spin diffusion length in Alq$_3$ was estimated as $43 \pm 5$ nm at 80 K. However, the subtle correlations between microstructure and magnetotransport indicate the importance of interfacial effects in these systems.Comment: 21 pages, 11 figures and 2 table

Prevalence of Dyskinesia and OFF by 30-Minute Intervals Through the Day and Assessment of Daily Episodes of Dyskinesia and OFF: Novel Analyses of Diary Data from Gocovri Pivotal Trials.

BACKGROUND: Parkinson\u27s disease (PD) patients using levodopa commonly develop dyskinesia and OFF episodes that reduce quality of life. OBJECTIVE: Evaluate prevalence of troublesome dyskinesia and OFF through the day, assessed by 30-minute intervals, as well as the mean number and duration of troublesome dyskinesia and OFF episodes, transitions between PD states, and effects of Gocovri® (amantadine) extended release capsules on these episodes. METHODS: Evaluate diary data from pooled Gocovri phase 3, placebo-controlled trials-analyzed for 17 hours following wake-up-at baseline and week 12. RESULTS: Diaries were evaluable for 162 patients. At baseline, 67% of patients woke up OFF, with prevalence decreasing to 13% at 2 hours and then remaining relatively steady at ∼12% (range, 6-17%) across half-hour intervals thereafter. Troublesome dyskinesia prevalence rose steadily from 5% to 24% over the first 2 hours, then fluctuated between 20% and 44% through the rest of the waking day. At baseline, patients experienced a mean of 3.0 daily episodes of troublesome dyskinesia (average duration 2.0 hours each), and 2.2 daily episodes of OFF (average duration 1.1 hour each). At week 12, Gocovri-treated patients showed greater reductions than placebo in troublesome dyskinesia and OFF episodes per day (treatment difference: -1.0 episodes and -0.4 episodes, respectively) and average episode duration (treatment difference: -0.6 hours and -0.3 hours, respectively). Mean duration of individual episodes of ON without troublesome dyskinesia (Good ON) increased by 5.0 hours for Gocovri, compared with 2.0 hours for placebo. Patients taking Gocovri experienced 2.2 fewer transitions between states than patients taking placebo. CONCLUSIONS: Troublesome dyskinesia and OFF occurred in the morning and throughout the waking day. Gocovri-treated patients experienced fewer, shorter episodes of both troublesome dyskinesia and OFF, thereby increasing the duration of continuous Good ON episodes and reducing the frequency of transitions between motor states

Revised Stellar Properties of Kepler Targets for the Q1-17 (DR25) Transit Detection Run

The determination of exoplanet properties and occurrence rates using Kepler data critically depends on our knowledge of the fundamental properties (such as temperature, radius and mass) of the observed stars. We present revised stellar properties for 197,096 Kepler targets observed between Quarters 1-17 (Q1-17), which were used for the final transiting planet search run by the Kepler Mission (Data Release 25, DR25). Similar to the Q1--16 catalog by Huber et al. the classifications are based on conditioning published atmospheric parameters on a grid of Dartmouth isochrones, with significant improvements in the adopted methodology and over 29,000 new sources for temperatures, surface gravities or metallicities. In addition to fundamental stellar properties the new catalog also includes distances and extinctions, and we provide posterior samples for each stellar parameter of each star. Typical uncertainties are ~27% in radius, ~17% in mass, and ~51% in density, which is somewhat smaller than previous catalogs due to the larger number of improved logg constraints and the inclusion of isochrone weighting when deriving stellar posterior distributions. On average, the catalog includes a significantly larger number of evolved solar-type stars, with an increase of 43.5% in the number of subgiants. We discuss the overall changes of radii and masses of Kepler targets as a function of spectral type, with particular focus on exoplanet host stars.Comment: 19 pages, 13 figures. ApJS in pres

Constructing a Man-Made Oyster Reef in the Little Hellgate Salt Marsh, Randall\u27s Island, New York: A Project Overview

Atlantic oyster beds provide instrumental estuarine infrastructure, shaping waterways and mediating the impacts of storm surge. In addition, the reefs provide habitat for numerous species. The oysters themselves are expert filter feeders, remediating poor water quality at little cost to the organism. As the free-swimming oyster larvae (spat) only settle on the shells of their forbears, the reefs are essential in perpetuation of the species, as well as for the continuation of such invaluable ecosystem services. Oyster reefs of the New York City waterway system have long been subject to environmental degradation, from water pollution and sedimentation to dredging. Randall’s Island Park Alliance’s Natural Areas crew received a donation of six hundred oysters from the New York Harbor School to conduct a test for the viability of a manmade oyster garden in 2014. Three hundred oysters were placed in each cage, which were then established in different parts of Randall’s Island Park’s Harlem River shoreline. One was hung by the 103rd Street footbridge seawall and the other was placed on the seawall by the Little Hellgate Salt Marsh inlet. The cages were monitored monthly for oyster growth and mortality rate, and water quality was tested as well. After a year of monitoring, it was determined that the Little Hellgate Salt Marsh was the ideal site for a man-made oyster reef—oysters had shown significantly more growth and a lower mortality rate than those in the cage at the 103rd St. Bridge, most likely due to the protective shape of the salt marsh inlet. The cages that will serve as the reef framework were constructed in the spring of this year and await the placement of oyster shells, which are being treated and sterilized (completion is projected to be late fall 2015). Future monitoring of oyster colonization and growth are expected, with the aim that water quality will measurably improve