Modelling and analysis of planar cell polarity

Planar cell polarity (PCP) occurs in the epithelia of many animals and can lead to the alignment of hairs, bristles and feathers; physiologically, it can organise ciliary beating. Here we present two approaches to modelling this phenomenon. The aim is to discover the basic mechanisms that drive PCP, while keeping the models mathematically tractable. We present a feedback and diffusion model, in which adjacent cell sides of neighbouring cells are coupled by a negative feedback loop and diffusion acts within the cell. This approach can give rise to polarity, but also to period two patterns. Polarisation arises via an instability provided a sufficiently strong feedback and sufficiently weak diffusion. Moreover, we discuss a conservative model in which proteins within a cell are redistributed depending on the amount of proteins in the neighbouring cells, coupled with intracellular diffusion. In this case polarity can arise from weakly polarised initial conditions or via a wave provided the diffusion is weak enough. Both models can overcome small anomalies in the initial conditions. Furthermore, the range of the effects of groups of cells with different properties than the surrounding cells depends on the strength of the initial global cue and the intracellular diffusion

Is a persistent global bias necessary for the establishment of planar cell polarity?

Planar cell polarity (PCP) — the coordinated polarisation of a whole field of cells within the plane of a tissue — relies on the interaction of three modules: a global module that couples individual cellular polarity to the tissue axis, a local module that aligns the axis of polarisation of neighbouring cells, and a readout module that directs the correct outgrowth of PCP-regulated structures such as hairs and bristles. While much is known about the molecular components that are required for PCP, the functional details of—and interactions between—the modules remain unclear. In this work, we perform a mathematical analysis of two previously proposed computational models of the local module (Amonlirdviman et al., Science, 307, 2005; Le Garrec et al., Dev. Dyn., 235, 2006). Both models can reproduce wild-type and mutant phenotypes of PCP observed in the Drosophila wing under the assumption that a tissue-wide polarity cue from the global module persists throughout the development of PCP. We demonstrate that both models can also generate tissue-level PCP when provided with only a transient initial polarity cue. However, such transient cues are not sufficient to ensure robustness of the resulting cellular polarisation

Network mechanisms of intentional learning.

The ability to learn new tasks rapidly is a prominent characteristic of human behaviour. This ability relies on flexible cognitive systems that adapt in order to encode temporary programs for processing non-automated tasks. Previous functional imaging studies have revealed distinct roles for the lateral frontal cortices (LFCs) and the ventral striatum in intentional learning processes. However, the human LFCs are complex; they house multiple distinct sub-regions, each of which co-activates with a different functional network. It remains unclear how these LFC networks differ in their functions and how they coordinate with each other, and the ventral striatum, to support intentional learning. Here, we apply a suite of fMRI connectivity methods to determine how LFC networks activate and interact at different stages of two novel tasks, in which arbitrary stimulus-response rules are learnt either from explicit instruction or by trial-and-error. We report that the networks activate en masse and in synchrony when novel rules are being learnt from instruction. However, these networks are not homogeneous in their functions; instead, the directed connectivities between them vary asymmetrically across the learning timecourse and they disengage from the task sequentially along a rostro-caudal axis. Furthermore, when negative feedback indicates the need to switch to alternative stimulus-response rules, there is additional input to the LFC networks from the ventral striatum. These results support the hypotheses that LFC networks interact as a hierarchical system during intentional learning and that signals from the ventral striatum have a driving influence on this system when the internal program for processing the task is updated.This work was supported by Medical Research Council Grant (U1055.01.002.00001.01) and a European Research GrantPCIG13-GA-2013-618351 to AH. JBR is supported by the Wellcome Trust (103838). The authors report no conflicts of interest.This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.neuroimage.2015.11.06

Respuesta de cuatro variedades de caña de azúcar a la aplicación de cuatro niveles de cal, manteniendo una fertilización basal constante.

Con el fín de observar el comportamiento de la caña de azúcar en un oxisol de la altillanura plana en el departamento del Meta (Carimagua) se llevó a cabo un proyecto con el mínimo de fertilización y dosis variables de cal agrícola. El ensayo se inició en 1979 realizándose en 2 cortes. La variedades introducidas: POJ 2858, CP 3834 Mex 5229 y CP 57603 con 4 niveles de cal. Se empleó un nivel constante de cal dolomítica (fuente de Mg) de 0.5 t/ha y dosis de cal 2.0, 4.0 y 8.0 t/ha con fertilización constante de N, P2O5 K2O de 80, 240 y 80 kg/ha. En el primer corte la variedad de mayor rendimiento con 0.5 t/ha de cal (63.4 por ciento de saturación de Al), fué CP 57603 (48.6 t/ha y la menor Mex 5229 (36.5 t/ha). La mayor producción se obtuvo con la variedad CP 57603 con 8.5 de cal (38.8 por ciento de saturación de Al). En el segundo corte las aplicaciones de cal 0.5 t/ha tienen el más alto porcentaje de saturación de Al 69.9 por ciento y el más bajo de Ca 15.3 por ciento con 2.5 t/ha de cal presenta 51.8 por ciento de Al y 33.4 por ciento de Ca. Se concluye que la caña de azúcar es un cultivo promisorio para la altillanura plana. La mejor variedad CP 57603 la cual se mantuvo constante en dos cortes. La dosis óptima de cal está entre 3.5 y 4.5 t/haCaña de azúcar-Saccharum officinaru

Thermal aspects of a low cost power electronic converter for high capacity, smart residential distribution networks

A key challenge facing the UK Distribution Network Operators (DNOs) today is the increasing demand for power being placed on residential networks. Also, the increase in distributed generation (DG) is now resulting in unacceptable local voltage rises and power quality issues. A cost effective solution to these problems can be achieved on the existing infrastructure by increasing the local network phase voltage to 400 V and stepping back down to 230 V at each house, using a DNO-owned, voltage regulated power electronic converter (PEC). The thermal and protection issues associated with the design of such a PEC, which is to be installed in the meterbox of each property, are discussed in this paper

Association between intimate partner violence and the use of maternal health care services among married Malawian women

Background: Maternal and child health care (MCH) services aim at improving the overall health outcomes of both the mother and newborn. Intimate partner violence (IPV) has been linked with poor health outcomes and under usage of MCH services. In Malawi, IPV is a persistent problem, while MCH services’ uptake remains a constant challenge. However, there is limited information on the association between IPV and MCH services in Malawi. The study examined the association between IPV and the use of MCH services among married Malawian women. Methods: The 2015–16 Malawi demographic and health survey was used to analyze the association of IPV and the use of MCH services among 2712 married Malawian women. Multivariable logistic regression models were used to estimate the strength of association. Results: Approximately 41.4% of the women reported experiencing IPV. Specifically, 27.8%, 19.3%, and 23.6% reported experiencing physical, sexual, and emotional violence, respectively. Women who reported experiencing any form of IPV had a 34% reduced likelihood of delivering at a health facility [adjusted odds ratio (aOR): 0.66; 95% confidence interval (CI) 0.46–0.96] or were 36% less likely [aOR: 0.64; 95% CI 0.46–0.90] to have had skilled assistance during delivery compared to those who never experienced IPV. Conclusion: IPV was associated with MCH services use, specifically delivery at a health facility and skilled birth attendants. The high prevalence of IPV underscores the need to design effective programs to raise awareness regarding IPV and reduce IPV. Reducing IPV may be a promising means to support a more integrated and sustainable approach to improve the use of MCH services

Factors associated with complementary feeding practices among children aged 6-23 mo in Malawi: an analysis of the Demographic and Health Survey 2015-2016

Background: Optimal child complementary feeding practices are crucial for nutritional status, growth, development and health, and ultimately affect child survival. This is the first population-based study in Malawi that aimed to examine factors associated with complementary feeding practices among children aged 6-23 mo. Methods: Utilizing data from the 2015-16 Malawi Demographic and Health Survey (MDHS), 4732 children aged 6-23 mo and their mothers were analysed. The MDHS produced a nationally representative sample using a multistage cluster sampling design that included sampling weights. The impact of child, maternal, household, community and health service utilization factors on complementary feeding practices was examined using the generalized estimating equation logistic regression. Results: After controlling for a wide range of covariates, children from mothers with secondary or post-secondary education and from mothers working in agriculture and living in the central region were significantly more likely to have timely introduction to solid, semi-solid or soft food. Surprisingly, being >1 y of age was associated with reduced odds of achieving minimum meal frequency. In addition, children >1 y of age from mothers older than 24 y and from mothers with primary, secondary and post-secondary education were significantly more likely to achieve minimum dietary diversity. Children from rich households were more likely to achieve both minimum dietary diversity and minimum acceptable diet. Finally, exposure to mass media was significantly associated with increased odds of achieving minimum meal frequency, minimum dietary diversity and minimum acceptable diet. Conclusions: Public health strategies aimed at reducing childhood undernutrition should focus on children from poor households whose mothers have no formal education and are unemployed. In addition, exposure to mass media had a positive impact on the three complementary feeding indicators. Therefore behaviour change communication messages through mass media aimed at promoting child nutrition are necessary to achieve optimal child complementary feeding practices

Tracking immunization coverage, dropout and equity gaps among children ages 12–23 months in Malawi – bottleneck analysis of the Malawi Demographic and Health Survey

Background: Between 2010 and 2016, the proportion of children 12–23 months of age who received full immunization in Malawi decreased from 81% to 76%. Most studies on immunization have mainly focused on the risk factors of vaccination coverage while data on dropouts and equity gaps is very scanty. Thus the aim of the present study was to describe the trend in immunization coverage, dropout rates and effective immunization coverage (EIC) among children ages 12–23 months in Malawi. Methods: Secondary analyses of the cross-sectional data obtained from the three waves of the Demographic and Health Surveys (2004, 2010 and 2015–16) were conducted. Using bottleneck analysis, outputs were generated based on service coverage, demand/equity (service utilization) and quality (full immunization). The World Health Organization benchmarks were used to assess gaps in the immunization coverage indicators. Results: The coverage was >90.0% in most of the antigens while full immunization status was estimated at 65%, 84% and 73% in 2004, 2010 and 2015, respectively. The highest coverage was observed in Bacillus Calmette–Guérin (BCG) and lowest in oral polio vaccine 1 (OPV1). OPV1 coverage was <90% in the 2004 cohort year, while pentavalent 3 (Penta3) and measles-containing vaccine 1 (MCV1) coverages were <90% in 2004. Dropout rates of Penta3 and MCV1 were significantly >10% in 2004. The logistic regression analyses showed that children were significantly less likely to be immunized with Penta3 and MCV1 in all cohort years compared with Penta1. Conclusions: Although immunization coverage was in line with the national and district targets for various antigens, full vaccination coverage (FVC) is still lagging behind. Furthermore, the dropout rates for Penta3 and MCV1 showed upside U-shaped patterns. Thus health education, supervision and orientation of service providers are urgently needed to address disparities that are existing in FVC

Being Warm Being Happy: fuel poverty and adults with intellectual disabilities

Self-determination has been acknowledged as a criticalconstruct for people with intellectual disability (ID), given the benefits itspromotion entails towards an enhanced quality of life..

Optimal detection of burst events in gravitational wave interferometric observatories

We consider the problem of detecting a burst signal of unknown shape. We introduce a statistic which generalizes the excess power statistic proposed by Flanagan and Hughes and extended by Anderson et al. The statistic we propose is shown to be optimal for arbitrary noise spectral characteristic, under the two hypotheses that the noise is Gaussian, and that the prior for the signal is uniform. The statistic derivation is based on the assumption that a signal affects only affects N samples in the data stream, but that no other information is a priori available, and that the value of the signal at each sample can be arbitrary. We show that the proposed statistic can be implemented combining standard time-series analysis tools which can be efficiently implemented, and the resulting computational cost is still compatible with an on-line analysis of interferometric data. We generalize this version of an excess power statistic to the multiple detector case, also including the effect of correlated noise. We give full details about the implementation of the algorithm, both for the single and the multiple detector case, and we discuss exact and approximate forms, depending on the specific characteristics of the noise and on the assumed length of the burst event. As a example, we show what would be the sensitivity of the network of interferometers to a delta-function burst.Comment: 21 pages, 5 figures in 3 groups. Submitted for publication to Phys.Rev.D. A Mathematica notebook is available at http://www.ligo.caltech.edu/~avicere/nda/burst/Burst.nb which allows to reproduce the numerical results of the pape