Continuum of solutions for an elliptic problem with critical growth in the gradient

We consider the boundary value problem \begin{equation*} - \Delta u = \lambda c(x)u+ \mu(x) |\nabla u|^2 + h(x), \quad u \in H^1_0(\Omega) \cap L^{\infty}(\Omega) \eqno{(P_{\lambda})} \end{equation*} where $\Omega \subset \R^N, N \geq 3$ is a bounded domain with smooth boundary. It is assumed that $c\gneqq 0$, $c,h$ belong to $L^p(\Omega)$ for some $p > N/2$ and that $\mu \in L^{\infty}(\Omega).$ We explicit a condition which guarantees the existence of a unique solution of $(P_{\lambda})$ when $\lambda <0$ and we show that these solutions belong to a continuum. The behaviour of the continuum depends in an essential way on the existence of a solution of $(P_0)$. It crosses the axis $\lambda =0$ if $(P_0)$ has a solution, otherwise if bifurcates from infinity at the left of the axis $\lambda =0$. Assuming that $(P_0)$ has a solution and strenghtening our assumptions to $\mu(x)\geq \mu_1>0$ and $h\gneqq 0$, we show that the continuum bifurcates from infinity on the right of the axis $\lambda =0$ and this implies, in particular, the existence of two solutions for any $\lambda >0$ sufficiently small.Comment: This second version include added Reference

Density and Cover Preferences of Black-And-Rufous Elephant-Shrews (\u3cem\u3eRhynchocyon petersi\u3c/em\u3e) in Chome Forest Reserve, Tanzania

The objective of this study was to determine the density and habitat preference of the Black-andrufous elephant-shrew (Rhynchocyon petersi) in Chome Forest Reserve, Tanzania. Chome Forest (143km2) is located in the South Pare Mountains and provides critical habitat for endangered R. petersi. Twelve 300m transects were cut through the centre of the forest in an east-west direction and the number of elephant-shrew nests within 2.5 meters on each side of the transects was recorded. The mean number of nests per 100m transect (0.39 ± 0.47 [1SE]) translated to a density estimate of 19 elephant-shrews per km2 (SE=23). Nest sites tended to be found in areas with greater than expected cover at the low (R. petersi is lower in the Chome Forest Reserve than in most populations in the Eastern Arc Mountains. The reasons for this difference and the conservation implications are discussed

Polar Cap Patches and the Tongue of Ionization: A Survey of GPS TEC Maps from 2009 to 2015

The source and structuring mechanisms for F region density patches have been subjects of speculation and debate for many years. We have made a survey of mappings of total electron content (TEC) between the years 2009 and 2015 from the web‐based Madrigal data server in order to determine when patches and/or a tongue of ionization (TOI) have been present in the Northern Hemisphere polar cap; we find that there is a UT and seasonal dependence that follows a specific pattern. This finding sheds considerable light upon the old question of the source of polar cap patches, since it virtually eliminates potential patch plasma sources that do not have a UT/seasonal dependence, for example, particle precipitation or flux transfer events. We also find that the frequency of occurrence of patches or TOIs has little to do with the level of geomagnetic activity

Epistemic and Aleatoric Uncertainty Quantification and Surrogate Modelling in High-Performance Multiscale Plasma Physics Simulations

This work suggests several methods of uncertainty treatment in multiscale modelling and describes their application to a system of coupled turbulent transport simulations of a tokamak plasma. We propose a method to quantify the usually aleatoric uncertainty of a system in a quasi-stationary state, estimating the mean values and their errors for quantities of interest, which is average heat fluxes in the case of turbulence simulations. The method defines the stationarity of the system and suggests a way to balance the computational cost of simulation and the accuracy of estimation. This allows, contrary to many approaches, to incorporate aleatoric uncertainties in the analysis of the model and to have a quantifiable decision for simulation runtime. Furthermore, the paper describes methods for quantifying the epistemic uncertainty of a model and the results of such a procedure for turbulence simulations, identifying the model's sensitivity to particular input parameters and sensitivity to uncertainties in total. Finally, we introduce a surrogate model approach based on Gaussian Process Regression and present a preliminary result of training and analysing the performance of such a model based on turbulence simulation data. Such an approach shows a potential to significantly decrease the computational cost of the uncertainty propagation for the given model, making it feasible on current HPC systems

Physiological health parameters among college students to promote chronic disease prevention and health promotion

This study aimed to provide physiologic health risk parameters by gender and age among college students enrolled in a U.S. Midwestern University to promote chronic disease prevention and ameliorate health. A total of 2615 college students between 18 and 25 years old were recruited annually using a series of cross-sectional designs during the spring semester over an 8-year period. Physiologic parameters measured included body mass index (BMI), percentage body fat (%BF), blood serum cholesterol (BSC), and systolic (SBP) and diastolic (DBP) blood pressure. These measures were compared to data from NHANES to identify differences in physiologic parameters among 18-25 year olds in the general versus college-enrolled population. A quantitative instrument assessed health behaviors related to physical activity, diet, and licit drug use. Results suggest that average physiologic parameters from18 to 25 year olds enrolled in college were significantly different from parameters of 18-25 year olds in the general population. Generally, men reported higher percentiles for BMI, SBP, and DBP than women, but lower %BF and BSC percentiles than women at each age. SBP and DBP significantly increased with age and alcohol use. Students in the lowest (5th) and highest percentiles (95th and 75th), for most age groups, demonstrated DBP, BMI, and %BF levels potentially problematic for health and future development of chronic disease based on percentiles generated for their peer group. Newly identified physiologic parameters may be useful to practitioners serving college students 18–25 years old from similar institutions in determining whether behavior change or treatment interventions are appropriate

Health Needs Assessment: Impact on Planning and Purchasing in the Public Health Sector in New Zealand

Health needs assessment (HNA) is one of the features of the New Zealand health system established by the New Zealand Public Health and Disability Act 2000. District Health Boards (DHBs) are to conduct HNAs, and planning of health services is intended to take into account the health needs of the population. Key questions for research relate to the impact of HNA on DHB planning and purchasing in a political/bureaucratic model of governance. This research was undertaken within a public policy framework that focused on evaluating the reforms against policy goals and expectations, and particularly against the influences that might be predicted from the HNA and prioritisation policy. Consideration was given to the range and effectiveness of past HNAs as well as the expectations and experiences of the DHB model in regard to HNA. Document analysis and 34 interviews were conducted regarding 50 HNAs conducted in the public health sector from 1991-2000 to assess their impact on service delivery, decision-making, and policy. Document analysis was undertaken on DHB HNAs, prioritisation frameworks, board priorities, District Strategic Plans, and District Annual Plans for each of 20 DHBs. Planning and Funding managers were interviewed using semi-structured interview techniques to ascertain their experiences and views regarding the use of HNAs in planning. Grounded theory approaches were mainly used for the interview analysis. Case studies of five DHBs provided an in-depth understanding of the connections between health needs assessment, prioritisation, District Strategic Plans and District Annual Plans. Collection of contextual data provided an understanding of the influence of other policy decisions made locally or nationally. Using triangulation, conclusions were drawn regarding the effectiveness and impact of HNA and prioritisation on planning and health service purchasing by DHBs. The implications for public policy were then considered. Recent needs assessments conducted by DHBs mostly met the minimum requirements of the Ministry of Health, but the quality was variable. DHB Planning and Funding Managers were unanimously positive regarding the usefulness of HNAs, and felt that there were good connections between them and the planning process (Connection Score). However, the impact of HNAs on planning and purchasing measured using document analysis (Impact Factor) was lower than expected. A number of barriers to effective use were identified. More focused HNA by DHBs is recommended with the use of mixed scanning approaches and service development groups directed towards specific service planning areas. Recommendations are made regarding future policy for HNA and prioritisation

FabR regulates Salmonella biofilm formation via its direct target FabB

Background: Biofilm formation is an important survival strategy of Salmonella in all environments. By mutant screening, we showed a knock-out mutant of fabR, encoding a repressor of unsaturated fatty acid biosynthesis (UFA), to have impaired biofilm formation. In order to unravel how this regulator impinges on Salmonella biofilm formation, we aimed at elucidating the S. Typhimurium FabR regulon. Hereto, we applied a combinatorial high-throughput approach, combining ChIP-chip with transcriptomics. Results: All the previously identified E. coli FabR transcriptional target genes (fabA, fabB and yqfA) were shown to be direct S. Typhimurium FabR targets as well. As we found a fabB overexpressing strain to partly mimic the biofilm defect of the fabR mutant, the effect of FabR on biofilms can be attributed at least partly to FabB, which plays a key role in UFA biosynthesis. Additionally, ChIP-chip identified a number of novel direct FabR targets (the intergenic regions between hpaR/hpaG and ddg/ydfZ) and yet putative direct targets (i.a. genes involved in tRNA metabolism, ribosome synthesis and translation). Next to UFA biosynthesis, a number of these direct targets and other indirect targets identified by transcriptomics (e.g. ribosomal genes, ompA, ompC, ompX, osmB, osmC, sseI), could possibly contribute to the effect of FabR on biofilm formation. Conclusion: Overall, our results point at the importance of FabR and UFA biosynthesis in Salmonella biofilm formation and their role as potential targets for biofilm inhibitory strategies

Hemispherical Shifted Symmetry in Polar Cap Patch Occurrence: A Survey of GPS TEC Maps From 2015–2018

Much theoretical and observational work has been devoted to studying the occurrence of F region polar cap patches in the Northern Hemisphere; considerably less work has been applied to the Southern Hemisphere. In recent years, the Madrigal database of mappings of total electron content (TEC) has improved in Southern Hemisphere coverage, to the point that we can now carry out a study of patch frequency and occurrence. We find that Southern Hemisphere patch occurrence is very similar to that of the Northern Hemisphere with a half‐year offset, plus an offset in universal time of approximately 12 hr. This is further supported by running an ionospheric model for both hemispheres and applying the same patch‐to‐background technique. Further, we present a simple physical mechanism involving a sunlit dayside plasma source concurrent with a dark polar cap, which yields a patch‐to‐background pattern very much like that seen in the TEC mappings for both hemispheres