Image Enhancement for Tracking the Translucent Larvae of Drosophila melanogaster

Drosophila melanogaster larvae are model systems for studies of development, synaptic transmission, sensory physiology, locomotion, drug discovery, and learning and memory. A detailed behavioral understanding of larvae can advance all these fields of neuroscience. Automated tracking can expand fine-grained behavioral analysis, yet its full potential remains to be implemented for the larvae. All published methods are unable to track the larvae near high contrast objects, including the petri-dish edges encountered in many behavioral paradigms. To alleviate these issues, we enhanced the larval contrast to obtain complete tracks. Our method employed a dual approach of optical-contrast boosting and post-hoc image processing for contrast enhancement. We reared larvae on black food media to enhance their optical contrast through darkening of their digestive tracts. For image processing we performed Frame Averaging followed by Subtraction then Thresholding (FAST). This algorithm can remove all static objects from the movie, including petri-dish edges prior to processing by the image-tracking module. This dual approach for contrast enhancement also succeeded in overcoming fluctuations in illumination caused by the alternating current power source. Our tracking method yields complete tracks, including at the edges of the behavioral arena and is computationally fast, hence suitable for high-throughput fine-grained behavioral measurements

'Changing the Culture’ – A feminist academic activist critique

The Universities UK (UUK) Taskforce (2016) report, ‘Changing the Culture’, has been seen as a turning point in UK universities’ responses to gender based violence (GBV) (Richardson and Beer, 2017). Institutional changes have occurred as a response to grassroots feminist activism and resistance to GBV, focusing on sexual violence, harassment and ‘lad culture’ in universities (Cobb and Godden-Rasul, 2017; Lewis, Marine and Kenney, 2016). This article will argue that the neoliberal marketization of higher education, concurrent with the persistence of misogyny and patriarchy, creates an environment where GBV is normalised, and feminist voices are marginalised and silenced. Interviews with academics show support for victim/survivors on campus often falls to particular academic staff. When initiatives for change, led by institutional management, are limited to protecting the ‘reputation’ of the university, it furthermore falls on academics to challenge not only GBV, but also the reactive and uncritical responses offered by institutions. We contend that national, institutional and individual responses to GBV must consider the meaning of ‘cultural change’ beyond policy reform, zero tolerance campaigns and condemnation of GBV. Attempts to enact true cultural change must analyse the broader issue of sexism, its intersections with further structural issues, and the ways in which this plays out within the neoliberal institution to the detriment of students and staff

A semi-Markov model for stroke with piecewise-constant hazards in the presence of left, right and interval censoring.

This paper presents a parametric method of fitting semi-Markov models with piecewise-constant hazards in the presence of left, right and interval censoring. We investigate transition intensities in a three-state illness-death model with no recovery. We relax the Markov assumption by adjusting the intensity for the transition from state 2 (illness) to state 3 (death) for the time spent in state 2 through a time-varying covariate. This involves the exact time of the transition from state 1 (healthy) to state 2. When the data are subject to left or interval censoring, this time is unknown. In the estimation of the likelihood, we take into account interval censoring by integrating out all possible times for the transition from state 1 to state 2. For left censoring, we use an Expectation-Maximisation inspired algorithm. A simulation study reflects the performance of the method. The proposed combination of statistical procedures provides great flexibility. We illustrate the method in an application by using data on stroke onset for the older population from the UK Medical Research Council Cognitive Function and Ageing Study

Numerical solutions of random mean square Fisher-KPP models with advection

[EN] This paper deals with the construction of numerical stable solutions of random mean square Fisher-Kolmogorov-Petrosky-Piskunov (Fisher-KPP) models with advection. The construction of the numerical scheme is performed in two stages. Firstly, a semidiscretization technique transforms the original continuous problem into a nonlinear inhomogeneous system of random differential equations. Then, by extending to the random framework, the ideas of the exponential time differencing method, a full vector discretization of the problem addresses to a random vector difference scheme. A sample approach of the random vector difference scheme, the use of properties of Metzler matrices and the logarithmic norm allow the proof of stability of the numerical solutions in the mean square sense. In spite of the computational complexity, the results are illustrated by comparing the results with a test problem where the exact solution is known.Ministerio de Economia y Competitividad, Grant/Award Number: MTM2017-89664-PCasabán Bartual, MC.; Company Rossi, R.; Jódar Sánchez, LA. (2020). Numerical solutions of random mean square Fisher-KPP models with advection. Mathematical Methods in the Applied Sciences. 43(14):8015-8031. https://doi.org/10.1002/mma.5942S801580314314FISHER, R. A. (1937). THE WAVE OF ADVANCE OF ADVANTAGEOUS GENES. Annals of Eugenics, 7(4), 355-369. doi:10.1111/j.1469-1809.1937.tb02153.xBengfort, M., Malchow, H., & Hilker, F. M. (2016). The Fokker–Planck law of diffusion and pattern formation in heterogeneous environments. Journal of Mathematical Biology, 73(3), 683-704. doi:10.1007/s00285-016-0966-8Okubo, A., & Levin, S. A. (2001). Diffusion and Ecological Problems: Modern Perspectives. Interdisciplinary Applied Mathematics. doi:10.1007/978-1-4757-4978-6SKELLAM, J. G. (1951). RANDOM DISPERSAL IN THEORETICAL POPULATIONS. Biometrika, 38(1-2), 196-218. doi:10.1093/biomet/38.1-2.196Aronson, D. G., & Weinberger, H. F. (1975). Nonlinear diffusion in population genetics, combustion, and nerve pulse propagation. Partial Differential Equations and Related Topics, 5-49. doi:10.1007/bfb0070595Aronson, D. ., & Weinberger, H. . (1978). Multidimensional nonlinear diffusion arising in population genetics. Advances in Mathematics, 30(1), 33-76. doi:10.1016/0001-8708(78)90130-5Weinberger, H. F. (2002). On spreading speeds and traveling waves for growth and migration models in a periodic habitat. Journal of Mathematical Biology, 45(6), 511-548. doi:10.1007/s00285-002-0169-3Weinberger, H. F., Lewis, M. A., & Li, B. (2007). Anomalous spreading speeds of cooperative recursion systems. Journal of Mathematical Biology, 55(2), 207-222. doi:10.1007/s00285-007-0078-6Liang, X., & Zhao, X.-Q. (2006). Asymptotic speeds of spread and traveling waves for monotone semiflows with applications. Communications on Pure and Applied Mathematics, 60(1), 1-40. doi:10.1002/cpa.20154E. Fitzgibbon, W., Parrott, M. E., & Webb, G. (1995). Diffusive epidemic models with spatial and age dependent heterogeneity. Discrete & Continuous Dynamical Systems - A, 1(1), 35-57. doi:10.3934/dcds.1995.1.35Kinezaki, N., Kawasaki, K., & Shigesada, N. (2006). Spatial dynamics of invasion in sinusoidally varying environments. Population Ecology, 48(4), 263-270. doi:10.1007/s10144-006-0263-2Jin, Y., Hilker, F. M., Steffler, P. M., & Lewis, M. A. (2014). Seasonal Invasion Dynamics in a Spatially Heterogeneous River with Fluctuating Flows. Bulletin of Mathematical Biology, 76(7), 1522-1565. doi:10.1007/s11538-014-9957-3Faou, E. (2009). Analysis of splitting methods for reaction-diffusion problems using stochastic calculus. Mathematics of Computation, 78(267), 1467-1483. doi:10.1090/s0025-5718-08-02185-6Doering, C. R., Mueller, C., & Smereka, P. (2003). Interacting particles, the stochastic Fisher–Kolmogorov–Petrovsky–Piscounov equation, and duality. Physica A: Statistical Mechanics and its Applications, 325(1-2), 243-259. doi:10.1016/s0378-4371(03)00203-6Siekmann, I., Bengfort, M., & Malchow, H. (2017). Coexistence of competitors mediated by nonlinear noise. The European Physical Journal Special Topics, 226(9), 2157-2170. doi:10.1140/epjst/e2017-70038-6McKean, H. P. (1975). Application of brownian motion to the equation of kolmogorov-petrovskii-piskunov. Communications on Pure and Applied Mathematics, 28(3), 323-331. doi:10.1002/cpa.3160280302Berestycki, H., & Nadin, G. (2012). Spreading speeds for one-dimensional monostable reaction-diffusion equations. Journal of Mathematical Physics, 53(11), 115619. doi:10.1063/1.4764932Cortés, J. C., Jódar, L., Villafuerte, L., & Villanueva, R. J. (2007). Computing mean square approximations of random diffusion models with source term. Mathematics and Computers in Simulation, 76(1-3), 44-48. doi:10.1016/j.matcom.2007.01.020Villafuerte, L., Braumann, C. A., Cortés, J.-C., & Jódar, L. (2010). Random differential operational calculus: Theory and applications. Computers & Mathematics with Applications, 59(1), 115-125. doi:10.1016/j.camwa.2009.08.061Casabán, M.-C., Cortés, J.-C., & Jódar, L. (2016). Solving linear and quadratic random matrix differential equations: A mean square approach. Applied Mathematical Modelling, 40(21-22), 9362-9377. doi:10.1016/j.apm.2016.06.017Sarmin, E. N., & Chudov, L. A. (1963). On the stability of the numerical integration of systems of ordinary differential equations arising in the use of the straight line method. USSR Computational Mathematics and Mathematical Physics, 3(6), 1537-1543. doi:10.1016/0041-5553(63)90256-8Sanz-Serna, J. M., & Verwer, J. G. (1989). Convergence analysis of one-step schemes in the method of lines. Applied Mathematics and Computation, 31, 183-196. doi:10.1016/0096-3003(89)90118-5Calvo, M. P., de Frutos, J., & Novo, J. (2001). Linearly implicit Runge–Kutta methods for advection–reaction–diffusion equations. Applied Numerical Mathematics, 37(4), 535-549. doi:10.1016/s0168-9274(00)00061-1Cox, S. M., & Matthews, P. C. (2002). Exponential Time Differencing for Stiff Systems. Journal of Computational Physics, 176(2), 430-455. doi:10.1006/jcph.2002.6995De la Hoz, F., & Vadillo, F. (2016). Numerical simulations of time-dependent partial differential equations. Journal of Computational and Applied Mathematics, 295, 175-184. doi:10.1016/j.cam.2014.10.006Company, R., Egorova, V. N., & Jódar, L. (2018). Conditional full stability of positivity-preserving finite difference scheme for diffusion–advection-reaction models. Journal of Computational and Applied Mathematics, 341, 157-168. doi:10.1016/j.cam.2018.02.031Kaczorek, T. 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Structure Characterization with Thermal Wave Imaging

Thermal imaging is a technique of recent interest for the nondestructive evaluation of materials. This method attempts to characterize the internal structure of a sample (perhaps to locate flaws-cracks, bubbles, corrosion, etc.) by using its surface temperature response to an external heating. Some recent work on this subject is detailed in [2], [3], [4] and [6]

Haptic subitizing across the fingers

Numerosity judgments of small sets of items (≤ 3) are generally fast and errorfree, while response times and error rates increase rapidly for larger numbers of items. We investigated an efficient process used for judging small numbers of items (known as subitizing) in active touch. We hypothesized that this efficient process for numerosity judgment might be related to stimulus properties that allow for efficient (parallel) search. Our results showed that subitizing was not possible forraised lines among flat surfaces, whereas this type of stimulus could be detected in parallel over the fingers. However, subitizing was possible when the number of fingers touching a surface had to be judged while the other fingers were lowered in mid-air. In the latter case, the lack of tactile input is essential, since subitizing was not enabled by differences in proprioceptive information from the fingers. Our results show that subitizing using haptic information from the fingers is possible only whensome fingers receive tactile information while other fingers do not

Holistic Dwelling Energy Assessment Protocol for Mine-water District Heat Network

UK buildings and energy infrastructures are heavily dependent on natural gas, and a large proportion is used for domestic space heating; but 50% is imported. Improving energy security and reducing carbon emissions are major government drivers for reducing gas dependency. So, there needs to be a wholesale shift in the energy provision to householders without impacting on thermal comfort levels, convenience or cost of supply. Electrical powered heat pumps are seen as a potential alternative system for heating new dwellings, but will they work in dwellings built prior to 1919? This paper investigates the energy demand of pre-1919 dwellings in Wales, UK as part of a feasibility study to extract water from disused coal mines to supply a district heat network. A holistic surveying protocol providing a more accurate/realistic assessment of total household heat demand is considered. The protocol’s techniques include condition surveys, air permeability and thermography tests, and heat loss calculations are discussed. The results were used to predict future (beyond 2019) heat demand after potential retrofit improvements, thereby informing the size of heat pumps required. The findings show estimated heat demand to be in close correlation to household energy bills, and that the use of heat pumps in pre-1919 dwellings is viable, provided sufficient improvement to thermal performance is possible

Building Performance Assessment Protocol for Timber Dwellings – Conducting Thermography Tests on Live Construction sites

This paper introduces the pan-Wales (UK) Home-Grown Homes (HGH) project (2018 to 2020) which focusses on three areas of improvement for delivering high performance, affordable and healthy homes. The HGH project is funded by Powys County Council, through the European Regional Development Fund’s Agricultural Stream. The HGH project is being delivered by Woodknowledge Wales in a consortium with Cardiff Metropolitan University (CMU), TRADA and Coed Cymru, with seven work packages. ‘More and Better Homes from Wood’ (work package (WP) WP3) focusses on the assessment of building performance for dwellings using timber, and is being delivered by a multi-disciplinary team at CMU through the Sustainable and Resilient Built Environment (SuRBe) group. This paper discusses the context and need for the HGH project as Wales launched its low carbon agenda in March 2019. The focus of this paper on introducing the building performance assessment (BPA) protocol to be implemented by SuRBe across several housing case studies in Wales, through the design, in-construction and occupancy phases, to address thermal and fire (TaF) performance issues, and impacts on occupants’ quality of life, comfort and safety. Preliminary results of in-construction testing on a live construction site are presented, with the challenges of conducting thermography tests whilst construction is in progress and weather conditions in spring in the UK (April 2019). This paper will be useful for academics, architects, building contractors, housing developers and professionals undertaking building performance assessment and evaluation on live construction sites