Wingless degradation in Drosophila imaginal discs.

Wingless is a secreted signalling molecule with multiple roles in patterning developing Drosophila. Previous work has shown that in the Drosophila embryonic epidermis, regulated degradation controls the distribution of Wingless protein, leading to an asymmetric range. The actual mechanism of Wingless degradation is not currently understood. I have used gain and loss of function experiments to examine the role of the signalling receptors, Dffizzled-2 and Arrow, in the control of Wingless degradation. Receptor mediated degradation can be subdivided into three steps: capture, endocytosis and targeting to lysosomes. Dfrizzled-2 is understood to play a key role in capture and indeed when Dfrizzled-2 is overexpressed, Wingless is stabilised at the cell surface. I have shown that Wingless and Dfrizzled-2 also colocalise in endocytic structures and by using mutants of Dfrizzled-2,1 have shown that Dfrizzled-2 is actively involved in the endocytosis of Wingless. Dfrizzled-2 therefore appears to function in the first two steps towards degradation, capture and endocytosis, however it is clearly not sufficient for degradation as when overexpressed, Dfrizzled-2 stabilises Wingless. This suggests that a limiting factor is absent that prevents Wingless captured by DFrizzled-2 from being degraded. I investigated the possibility that this limiting factor could be Arrow. I have shown that indeed, Arrow brings about the degradation of the Dfrizzled-2-Wingless complex. This activity is specific to Dfrizzled-2, since Arrow does not cause degradation of Wingless stabilised by Dally-like, another Wingless receptor. My results have led to a model where there is a division of labour between the two signalling receptors Dfrizzled-2 has functions in capture and endocytosis and Arrow, while also contributing somewhat to endocytosis, brings the signal that directs Wingless to lysosomes. Further investigations have been carried out to identify the specific motifs in Arrow that target Wingless to degradation

The properties of the cornea based on hyperspectral imaging : optical biomedical engineering perspective

Biomedical engineering is a unique area that allows fusion between two distinct fields of engineering and medicine. The integration of efforts from both fields promises progress through acquisition of information from tissues, cells, and organs through non-invasive methods of assessment. Here we investigate the ability of a hyperspectral device in extracting data from tissues through the wavelength spectrum, in foreseeing its potential in clinical diagnostics by simplifying methods of examination by clinicians in detecting corneal injuries. Hyperspectral imaging using 400 to 1000nm visible wavelength was used to scan five porcine eyes (injured and non-injured). Images were saved in three dimensional images of rows, columns, and depth slices at 1200 to 1300x804x604 and were processed. All laboratory works were performed in accordance with the general risk assessment of University of Strathclyde. In our results, analysis of the images reveals significant cue between 500 to 800nm bands in differentiating between injured and noninjured parts of the eye

Modelo de distribución de agua en suelo regado por goteo

[ES] Se desarrolla un modelo de simulación de la dinámica del agua en el suelo en riego localizado, denominado SIMDAS. Para el desarrollo del procedimiento numérico, se utiliza la teoría de flujo de agua en condiciones de no saturación, sin efecto histerético, resolviendo la ecuación de flujo axisimétrico sin y con extracción de agua por la planta a partir de un método en diferencias finitas, con la consideración de los distintos horizontes del suelo. Verificado el modelo en campo, los resultados que presenta son satisfactorios cuando no se contempla la presencia de cultivo, pero no lo son cuando interviene la extracción de agua por la planta. Por consiguiente, el grado de aceptabilidad es suficiente para fines de diseño agronómico de sistemas de riego localizado, pero no lo es para aquellos casos en que la extracción de agua por la planta interviene de manera destacada, como en el manejo y la programación de riegos.Ramírez De Cartagena Bisbe, F.; Sáinz Sánchez, MA. (1997). 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Soil Science Society of America Proceedings, 39: 604-613.Feddes R.A., Kowalik P.J., Zaradny H. (1978) Simulation of field water use and crop yield. PUDOC, Wageningen. 189pp.Ghali S.G. (1986) Mathematical modelling of soil moisture dynamics in trickle irrigated fields. Thesis, University of Southampton (UK).Gupta S.C., Larson W.E. (1979) Estimating soil wáter retention characteristics from particle size distribution, organic matter percent, and bulk density. Water Resources Research, 15(6): 1633-1635.Hillel D. (1977) Computer simulation of soil-waters dynamics. A compendium of recent work. IDRC, Ottawa, Canada. 214 pp.Jackson R.D. (1972) On the calculation of hydraulic conductivity. Soil Science Society of America Proceedings. 36: 380-382.Keller J. (1978) Trickle irrigation. In Irrigation (Ch. 7). National Engineering Handbook USDA-SCS.Keller J., Karmelid. (1975) Trickle irrigation design. Rain Bird Corp. Glendora, California USA. 133 pp.Khatri K.C. (1984) Simulation of soil moisture migration from a point source. Thesis, McGill University, Quebec, Canada.Kunze R.J., Uehara G., Graham K. (1968) Factors important in the calculation of hydraulic conductivity. Soil Science Soc. Amer. Proc., 32: 760-765.Lafolie F., Guenelon R., Van Genuchten M.TH. (1989a.) Analysis of water flow under trickle irrigation: I. Theory and numerical solution. Soil Science Society of America Journal, 53: 1310-1318.Lafolie P., Guenelon R., Van Genuchten M.TH. (1989b.) Analysis of water flow under trickle irrigation: II. Experimental evaluation. Soil Science Society of America Journal. 53: 1318-1323.Marino M.A., Tracy J.C. (1988) Flow of water through root-soil environment. Journal of Irrigation and Drainage Engineering, 114 (4): 588-604.Marshall T.J. (1958) A relation between permeability and size distribution of pores. Journal of Soil Science, 9 (8): 1-8.Millington R.J., Quirk J.P. (1959) Permeability of porous media Nature, 183: 378-388.Molz F.J., Remson I. (1970) Extraction term models of soil moisture use by transpiring plants. Water Resources Research, 6 (5): 1346-1356.Philip J.R. (1971) General theorem on steady infiltration from surface sources, with application to point and line sources. Soil Science Society of America Proceedings, 35: 867-871.Pradad R. (1988) A linear root water uptake model Journal of Hidrology, 99: 297-306.Raats P.A.C. (1977) Laterally confined, steady flows of water from sources and to sinks in unsaturated soils. Soil Science Society of America Journal, 41:294-304.Ramírez De Cartagena F. (1994) Simulación numerica de la dinámica del agua en el suelo. Aplicacion al diseño de sistemas de riego LAF. Tesis Doctoral. ETSEA. Universidad de Lleida.Rawls W.J., Brakensiek D.L. (1982) Estimating soil water retention from soil properties. 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Detection model based on representation of quantum particles by classical random fields: Born's rule and beyond

Recently a new attempt to go beyond quantum mechanics (QM) was presented in the form of so called prequantum classical statistical field theory (PCSFT). Its main experimental prediction is violation of Born's rule which provides only an approximative description of real probabilities. We expect that it will be possible to design numerous experiments demonstrating violation of Born's rule. Moreover, recently the first experimental evidence of violation was found in the triple slits interference experiment, see \cite{WWW}. Although this experimental test was motivated by another prequantum model, it can be definitely considered as at least preliminary confirmation of the main prediction of PCSFT. In our approach quantum particles are just symbolic representations of "prequantum random fields," e.g., "electron-field" or "neutron-field"; photon is associated with classical random electromagnetic field. Such prequantum fields fluctuate on time and space scales which are essentially finer than scales of QM, cf. `t Hooft's attempt to go beyond QM \cite{H1}--\cite{TH2}. In this paper we elaborate a detection model in the PCSFT-framework. In this model classical random fields (corresponding to "quantum particles") interact with detectors inducing probabilities which match with Born's rule only approximately. Thus QM arises from PCSFT as an approximative theory. New tests of violation of Born's rule are proposed.Comment: Relation with recent experiment on violation of Born's rule in the triple slit experiment is discussed; new experimental test which might confirm violation of Born's rule are presented (double stochsticity test and interference magnitude test); the problem of "double clicks" is discusse