1,605 research outputs found
Benefits and challenges of applying outcome mapping in an R4D project
The Community-based Fish Culture in Seasonal Floodplains and Irrigation Systems (CBFC) project is a five year research project supported by the Challenge Program on Water and Food (CPWF), with the aim of increasing productivity of seasonally occurring water bodies through aquaculture. The project has been implemented in Bangladesh, Cambodia, China, Mali and Vietnam, where technical and institutional options for community based aquaculture have been tested. The project began in 2005 and was completed in March 2010. There is an increasing demand for researchers to demonstrate the impact of the work within project time frames, yet development is a complex, non-linear process emerging from changes that traditional, managerial approaches to development fail to capture or to understand. Methods to address unanticipated change and increasingly important æsoftÆoutcomes, such as improved governance have not yet been widely tested or adopted. In response to this gap, this paper describes lessons learned during the pilot testing of Outcome Mapping as part of an action research process in Vietnam, and presents an abridged OM methodology for application at the community level.Research, Impact assessment, Livelihoods
Lateral diffusion of receptor-ligand bonds in membrane adhesion zones: Effect of thermal membrane roughness
The adhesion of cells is mediated by membrane receptors that bind to
complementary ligands in apposing cell membranes. It is generally assumed that
the lateral diffusion of mobile receptor-ligand bonds in membrane-membrane
adhesion zones is slower than the diffusion of unbound receptors and ligands.
We find that this slowing down is not only caused by the larger size of the
bound receptor-ligand complexes, but also by thermal fluctuations of the
membrane shape. We model two adhering membranes as elastic sheets pinned
together by receptor-ligand bonds and study the diffusion of the bonds using
Monte Carlo simulations. In our model, the fluctuations reduce the bond
diffusion constant in planar membranes by a factor close to 2 in the
biologically relevant regime of small bond concentrations.Comment: 6 pages, 5 figures; to appear in Europhysics Letter
Internal Medicine
This departmental history was written on the occasion of the UND Centennial in 1983.https://commons.und.edu/departmental-histories/1035/thumbnail.jp
History of the Department of Internal Medicine
This departmental history was written on the occasion of the UND Quasquicentennial in 2008.https://commons.und.edu/departmental-histories/1080/thumbnail.jp
Expansion velocity of a one-dimensional, two-component Fermi gas during the sudden expansion in the ballistic regime
We show that in the sudden expansion of a spin-balanced two-component Fermi
gas into an empty optical lattice induced by releasing particles from a trap,
over a wide parameter regime, the radius of the particle cloud grows
linearly in time. This allow us to define the expansion velocity from
. The goal of this work is to clarify the dependence of the
expansion velocity on the initial conditions which we establish from
time-dependent density matrix renormalization group simulations, both for a box
trap and a harmonic trap. As a prominent result, the presence of a
Mott-insulating region leaves clear fingerprints in the expansion velocity. Our
predictions can be verified in experiments with ultra-cold atoms.Comment: 8 pages 10 figures, version as published with minor stylistic change
Apoptosome activation, an important molecular instigator in 6-mercaptopurine induced Leydig cell death.
Leydig cells are crucial to the production of testosterone in males. It is unknown if the cancer chemotherapeutic drug, 6-mercaptopurine (6 MP), produces Leydig cell failure among adult survivors of childhood acute lymphoblastic leukemia. Moreover, it is not known whether Leydig cell failure is due to either a loss of cells or an impairment in their function. Herein, we show, in a subset of childhood cancer survivors, that Leydig cell failure is related to the dose of 6 MP. This was extended, in a murine model, to demonstrate that 6 MP exposure induced caspase 3 activation, and the loss of Leydig cells was independent of Bak and Bax activation. The death of these non-proliferating cells was triggered by 6 MP metabolism, requiring formation of both cytosolic reactive oxygen species and thiopurine nucleotide triphosphates. The thiopurine nucleotide triphosphates (with physiological amounts of dATP) uniquely activated the apoptosome. An ABC transporter (Abcc4/Mrp4) reduced the amount of thiopurines, thereby providing protection for Leydig cells. The studies reported here demonstrate that the apoptosome is uniquely activated by thiopurine nucleotides and suggest that 6 MP induced Leydig cell death is likely a cause of Leydig cell failure in some survivors of childhood cancer
Diffusion algebras
We define the notion of "diffusion algebras". They are quadratic
Poincare-Birkhoff-Witt (PBW) algebras which are useful in order to find exact
expressions for the probability distributions of stationary states appearing in
one-dimensional stochastic processes with exclusion. One considers processes in
which one has N species, the number of particles of each species being
conserved. All diffusion algebras are obtained. The known examples already used
in applications are special cases in our classification. To help the reader
interested in physical problems, the cases N=3 and 4 are listed separately.Comment: 29 pages; minor misprints corrected, few references adde
Probing material nonlinearity at various depths by time reversal mirrors
International audienceIn this letter, the time reversal mirror is used to focus elastic energy at a prescribed location and to analyze the amplitude dependence of the focus signal, thus providing the nonlinearity of the medium. By varying the frequency content of the focused waveforms, the technique can be used to probe the surface, by penetrating to a depth defined by the wavelength of the focused waves. The validity of this concept is shown in the presence of gradual and distributed damage in concrete by comparing actual results with a reference nonlinear measurement and X ray tomography images
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