Search

Abstract Background Deforestation and land use change is widespread in Madagascar, altering local ecosystems and creating opportunities for disease vectors, such as the Anopheles mosquito, to proliferate and more easily reach vulnerable, rural populations. Knowledge of risk factors associated with malaria infections is growing globally, but these associations remain understudied across Madagascar’s diverse ecosystems experiencing rapid environmental change. This study aims to uncover socioeconomic, demographic, and ecological risk factors for malaria infection across regions through analysis of a large, cross-sectional dataset. Methods The objectives were to assess (1) the ecological correlates of malaria vector breeding through larval surveys, and (2) the socioeconomic, demographic, and ecological risk factors for malaria infection in four ecologically distinct regions of rural Madagascar. Risk factors were determined using multilevel models for the four regions included in the study. Results The presence of aquatic agriculture (both within and surrounding communities) is the strongest predictive factor of habitats containing Anopheles larvae across all regions. Ecological and socioeconomic risk factors for malaria infection vary dramatically across study regions and range in their complexity. Conclusions Risk factors for malaria transmission differ dramatically across regions of Madagascar. These results may help stratifying current malaria control efforts in Madagascar beyond the scope of existing interventions.

Madagascar has experienced significant environmental change since 1960, particularly through forest clearing for agricultural expansion. Climatic patterns are undergoing change in Madagascar as well, with increasing temperatures, droughts, and cyclonic activity. The impact of these environmental and climatic changes will pose threats to food availability, income generation, and local ecosystems, with significant potential effects on the spatial and temporal distribution of disease burden. This study seeks to describe the health status of a large sample of geographically and socially diverse Malagasy communities through multiple clinical measurements, detailed social surveys, and paired data on regional variation in local ecologies. With an increased understanding of the current patterns of variation in human health and nutrition, future studies will be better able to identify associations with climate and anticipate and mitigate the burdens expected from larger, longer-term changes. Our mixed-method approach included an observational cross-sectional study. Research subjects were men, women, and children from 1,125 households evenly distributed across 24 communities in four ecologically and socio-demographically distinct regions of Madagascar. For these 1,125 households, all persons of both sexes and all ages therein (for a total of 6,292 individuals) were recruited into the research study and a total of 5,882 individuals were enrolled. Through repeated social survey recalls and focus group meetings, we obtained social and demographic data, including broad categories of seasonal movements, and characterized the fluctuation of income generation, food production and dietary consumption. Through collection of clinical and biological samples for both point-of-care diagnoses and laboratory analyses, we obtained detailed occurrence (and importantly co-occurrence) data on micronutrient nutritional, infectious disease, and non-communicable disease status. Our research highlights the highly variable social, cultural, and environmental contexts of health conditions in Madagascar, and the tremendous inter-regional, inter-community, and intra-community variation in nutritional and disease status. More than 30% of the surveyed population was afflicted by anemia and 14% of the population had a current malaria infection. This type of rich metadata associated with a suite of biological samples and nutritional and disease outcome data should allow disentangling some of the underlying drivers of ill health across the changing landscapes of Madagascar.

Background: Land-use changes, such as deforestation, can increase the transmission potential of a landscape by increasing the abundance of preferred microhabitats for malaria vectors. However, this relationship between malaria and deforestation is complex and depends on factors such as the type of land use, the local ecology of malaria vector species, and the health resources available to the human population. In Madagascar, despite alarmingly high rates of deforestation and concerning reports of increases in malaria, this link remains poorly studied. Methods: The feasibility of traditional approaches to studying the link between malaria and deforestation is limited for Madagascar because (i) health systems lack capacity to collect regular and accurate malaria data, especially in many rural areas, (ii) vector habitat preferences are poorly understood, and (iii) most existing malaria infection outcome datasets lack data on important mediating factors. To circumvent inadequacies in current data streams, we discuss a new framework that integrates novel primary data collection efforts on malaria infection and vector ecology from cross-sectional studies with longitudinal land-use data from remote sensing. Incorporating these data into hierarchical models allows us to infer structural associations between macro and micro level predictors of malaria risk in different ecological contexts in Madagascar. We compare the outputs from these models to analyses that can be conducted with robust data from the Brazilian health system. Findings: We report data on malaria burden, deforestation, its covariates, and vector larval habitat preference for four distinct, previously understudied, ecoregions of Madagascar. Risk factors of malaria infection vary in sign and magnitude of effect across ecological contexts. Interpretation: While data such as Brazil's allow for predictive modelling and assessment of temporally dynamic systems, our proposed modelling framework demonstrates variations in risk factors regionally in the meantime. This approach can help to mitigate current data gaps and better inform existing malaria control efforts in Madagascar during health system development. Funding: The Ren Che Foundation, Henry David Thoreau Foundation, Catholic Relief Services through a grand from United States Agency for International Development, and Madagascar Health and Environmental Research (MAHERY).

The hallmark of nematic order in iron-based superconductors is a resistivity anisotropy but it is unclear to which extent quasiparticle dispersions, lifetimes, and coherence contribute. While the lifted degeneracy of the Fe dxz and dyz dispersions has been studied extensively, only little is known about the two other factors. Here, we combine in situ strain tuning with ARPES and study the nematic response of the spectral weight in BaFe2As2. The symmetry analysis of the ARPES spectra demonstrates that the dxz band gains quasiparticle spectral weight compared to the dyz band for negative antisymmetric strain Δϵyy suggesting the same response inside the nematic phase. Our results are compatible with a different coherence of the dxz and dyz orbital within a Hund's metal picture. We also discuss the influence of orbital mixing.

Two-dimensional (2D) metal nitrides are new emerging materials with potential applications in electronics, energy storage, or conversion efficiency. In this paper, we report the synthesis of molybdenum nitride by nitriding molybdenum disulfide (MoS2) via a 700 °C ammonia (NH3) reactive heat treatment. A well-controlled uniform MoS2 thin film was prepared by atomic layer deposition (ALD). The progressive MoS2 nitriding reaction has been demonstrated and monitored by in situ reflectance measurements. These results have been confirmed by Raman and x-ray photoelectron spectrometry. This method paves the way to a new potential route to the synthesis of Mo nitride obtained from a well-controlled uniform 2D-MoS2 thin film deposited by ALD. [ABSTRACT FROM AUTHOR]

We study the following family of integral-valued alternating sums, where -infinity equal to or less than m equal to or less than infinity and n equal to or greater than 0 are integers [equation omitted]. We first consider h[subscript m](n) for m and n non-negative integers and show that it is of the form 2[superscript n + 2m] - P[subscript m](n), where P[subscript m]n may be represented as a polynomial of degree m in n, or expressed as a non-polynomial closed form given by a sum of binomial numbers. We then consider h[subscript m]n for m = -ImI a negative integer and for n a non-negative integer. This reveals, in particular, that h[subscript-ImI]n = 0 for 0 equal to or less than n equal to or less than ImI, that h[subscript-ImI](n) = 2[superscript n-2ImI] for n equal to or greater than 2ImI. We also show that h[subscript-ImI](n + ImI) is a polynomial of degree n - 1 in ImI, for fixed n equal to or greater than I, with ImI equal to or greater than I, and we give expressions for the coefficients.

Four different families of linear recurrences are derived for Catalan numbers. The derivations rest on John Riordan's 1973 generalization of Catalan numbers to a set of polynomials. Elementary differential and integral calculus techniques are used and the results should be of interest to teachers and students of introductory courses in calculus and number theory.

Two identities for the Bernoulli and for the Euler numbers are derived. These identities involve two special cases of central combinatorial numbers. The approach is based on a set of differential identities for the powers of the secant. Generalizations of the Mittag-Leffler series for the secant are introduced and used to obtain closed-form expressions for the coefficients.

A general method is presented for evaluating the sums of "m"th powers of the integers that can, and that cannot, be represented in the two-element Frobenius problem. Generating functions are introduced and used for that purpose. Explicit formulas for the desired sums are obtained and specific examples are discussed.

This note describes a method for evaluating the sums of the m -th powers of n consecutive terms of a general arithmetic sequence: { S[subscript m] = 0, 1, 2,...}. The method is based on the use of a differential operator that is repeatedly applied to a generating function. A known linear recurrence is then obtained and the m-th sum, S[subscript m], is expressed in terms of the preceding ones, S[subscript m]?1 , S[subscript m]?2,...., S[subscript 0]. This recurrence, which has been derived previously by methods other than the one used here, is solved explicitly for S[subscript m]. The final result is expressed in the form of a determinant of order (m + 1) by (m + 1). A comparison is made with other methods, including Inaba's recent approach in this journal.

The equation of motion for a mass that moves under the influence of a central, inverse-square force is formulated and solved as a problem in complex variables. To find the solution, the constancy of angular momentum is first established using complex variables. Next, the complex position coordinate and complex velocity of the particle are assumed to depend on time in an implicit manner only, through the polar angle phi, and angular momentum conservation is then imposed in the complex equation of motion itself, from the start. The general solution follows after performing but a single elementary integral, integer of d phi e[i phi], and the trajectory is shown to be a conic section. Energy conservation is also established using complex variables. The proposed method of solution is rigorous, yet concise and relatively simple to solve, so it could prove useful in a pedagogical context.