Malaria ecology, child mortality & fertility.

The broad determinants of fertility are thought to be reasonably well identified by demographers, though the detailed quantitative drivers of fertility levels and changes are less well understood. This paper uses a novel ecological index of malaria transmission to study the effect of child mortality on fertility. We find that temporal variation in the ecology of the disease is well-correlated to mortality, and pernicious malaria conditions lead to higher fertility rates. We then argue that most of this effect occurs through child mortality, and estimate the effect of child mortality changes on fertility. Our findings add to the literature on disease and fertility, and contribute to the suggestive evidence that child mortality reductions have a causal effect on fertility changes

Scaling Up Malaria Control in Africa: An Economic and Epidemiological Assessment

This paper estimates the number of people at risk of contracting malaria in Africa using GIS methods and the disease's epidemiologic characteristics. It then estimates yearly costs of covering the population at risk with the package of interventions (differing by level of malaria endemicity and differing for rural and urban populations) for malaria as recommended by the UN Millennium Project. These projected costs are calculated assuming a ramp-up of coverage to full coverage by 2008, and then projected out through 2015 to give a year-by-year cost of meeting the Millennium Development Goal for reducing the burden of malaria by 75% We conclude that the cost of comprehensive malaria control for Africa is US$3.0 billion per year on average, or around US$4.02 per African at risk.

Africa's Lagging Demographic Transition: Evidence from Exogenous Impacts of Malaria Ecology and Agricultural Technology

Much of Africa has not yet gone through a "demographic transition" to reduced mortality and fertility rates. The fact that the continent's countries remain mired in a Malthusian crisis of high mortality, high fertility, and rapid population growth (with an accompanying state of chronic extreme poverty) has been attributed to many factors ranging from the status of women, pro-natalist policies, poverty itself, and social institutions. There remains, however, a large degree of uncertainty among demographers as to the relative importance of these factors on a comparative or historical basis. Moreover, econometric estimation is complicated by endogeneity among fertility and other variables of interest. We attempt to improve estimation (particularly of the effect of the child mortality variable) by deploying exogenous variation in the ecology of malaria transmission and in agricultural productivity through the staggered introduction of Green Revolution, high-yield seed varieties. Results show that child mortality (proxied by infant mortality) is by far the most important factor among those explaining aggregate total fertility rates, followed by farm productivity. Female literacy (or schooling) and aggregate income do not seem to matter as much, comparatively.

An effective thermodynamic potential from the instanton with Polyakov-loop contributions

We derive an effective thermodynamic potential (Omega_eff) at finite temperature (T>0) and zero quark-chemical potential (mu_R=0), using the singular-gauge instanton solution and Matsubara formula for N_c=3 and N_f=2 in the chiral limit. The momentum-dependent constituent-quark mass is also obtained as a function of T, employing the Harrington-Shepard caloron solution in the large-N_c limit. In addition, we take into account the imaginary quark chemical potential mu_I = A_4, translated as the traced Polayakov-loop (Phi) as an order parameter for the Z(N_c) symmsetry, characterizing the confinement (intact) and deconfinement (spontaneously broken) phases. As a result, we observe the crossover of the chiral (chi) order parameter sigma^2 and Phi. It also turns out that the critical temperature for the deconfinment phase transition, T^Z_c is lowered by about (5-10)% in comparison to the case with a constant constituent-quark mass. This behavior can be understood by considerable effects from the partial chiral restoration and nontrivial QCD vacuum on Phi. Numerical calculations show that the crossover transitions occur at (T^chi_c,T^Z_c) ~ (216,227) MeV.Comment: 15 pages, 7 figure

Africa's Lagging Demographic Transition: Evidence from Exogenous Impacts of Malaria Ecology and Agricultural Technology

Much of Africa has not yet gone through a "demographic transition" to reduced mortality and fertility rates. The fact that the continent's countries remain mired in a Malthusian crisis of high mortality, high fertility, and rapid population growth (with an accompanying state of chronic extreme poverty) has been attributed to many factors ranging from the status of women, pro-natalist policies, poverty itself, and social institutions. There remains, however, a large degree of uncertainty among demographers as to the relative importance of these factors on a comparative or historical basis. Moreover, econometric estimation is complicated by endogeneity among fertility and other variables of interest. We attempt to improve estimation (particularly of the effect of the child mortality variable) by deploying exogenous variation in the ecology of malaria transmission and in agricultural productivity through the staggered introduction of Green Revolution, high-yield seed varieties. Results show that child mortality (proxied by infant mortality) is by far the most important factor among those explaining aggregate total fertility rates, followed by farm productivity. Female literacy (or schooling) and aggregate income do not seem to matter as much, comparatively

Intercellular Mitochondrial Transfer Using 3D Bioprinting

Mitochondria are one of the most complex and vital organelles in eukaryotic cells. In recent years, it has been shown that through intercellular mitochondrial transfer, this important organelle provides a critical role in tissue homeostasis, damaged tissue repair, and tumor progression under physiological conditions. However, the mechanism of mitochondrial transfer and its effect on various cellular microenvironments has not yet been defined. Understanding the metabolic effects of mitochondrial transfer between cells and exploring the signaling leading to the intercellular mechanisms could provide advancements in both translational medicine and cell therapy for cancer progression and age-related diseases. Our group has studied the ability of the normal mammary microenvironment to redirect cancer cells to a normal mammary epithelial cell fate both in vivo and in vitro using our 3D bioprinting system. Therefore, we sought to determine if mitochondrial transfer may play a role in mammary epithelium induced redirection of cancer cells. We used MCF-7 breast cancer cells and MCF-12a epithelial breast cells for experimentation. Using a fluorescent GFP-MITO lentivirus, we were able to mark mitochondrial protein in the MCF-12a epithelial cells to track mitochondrial transfer activity. The MCF-7 cells were labeled red to distinguish the two cell types. The cells were then co-cultured in 2D tissue flasks and printed into hydrogels using the 3D bioprinter. Using fluorescent microscopy, mitochondrial protein was observed traveling from epithelial to mammary cancer cells. We hypothesize this is done for cancer cells to stabilize mitochondria and improve metabolic function and ATP production. Further research to establish mitochondrial transfer, its mechanism(s), and molecular effects could lead insight into how this cellular communication rescues and normalizes metabolic factors of the mammary and stem cell microenvironment leading to potential fate redirection and cellular revitalization.https://digitalcommons.odu.edu/gradposters2022_healthsciences/1010/thumbnail.jp

The Revolution Will Be Open-Source: How 3D Bioprinting Can Change 3D Cell Culture

(First paragraph) The development of three-dimensional culture scaffolds represents a revolutionary step forward for in vitro culture systems. Various synthetic and naturally occurring substrates have been developed that support 3D growth of cells. In most fields, including mammary gland biology and tumorigenesis, the two most common substrates used are the basement membrane rich extracellur matrix (ECM) isolated from EngelbrethHolm-Swarm (EHS) mouse sarcomas (e.g. Matrigel) and collagen extracted from rat-tails. The processes of 3D culture in these two substrates has remained unchanged for nearly half a century: cells are either mixed with unpolymerized matrix to disperse them randomly throughout the substrate upon polymerization or overlaid randomly on top of a preformed hydrogel. While effective in generating organoid/tumoroid structures, the random nature of these processes has many drawbacks that limit the reproducibility and tunability of the experimental design. Furthermore, random cellular distributions limit the utility of these substrates for studying interactions within the cellular microenvironment, which have been shown to be critical for the control of stem and cancer cell function [1]

Tissue Specific Microenvironments: A Key Tool for Tissue Engineering and Regenerative Medicine

The accumulated evidence points to the microenvironment as the primary mediator of cellular fate determination. Comprised of parenchymal cells, stromal cells, structural extracellular matrix proteins, and signaling molecules, the microenvironment is a complex and synergistic edifice that varies tissue to tissue. Furthermore, it has become increasingly clear that the microenvironment plays crucial roles in the establishment and progression of diseases such as cardiovascular disease, neurodegeneration, cancer, and ageing. Here we review the historical perspectives on the microenvironment, and how it has directed current explorations in tissue engineering. By thoroughly understanding the role of the microenvironment, we can begin to correctly manipulate it to prevent and cure diseases through regenerative medicine techniques

Use of a spatially explicit individual-tree model (SORTIE/BC) to explore the implications of patchiness in structurally complex forests

The discipline of silviculture is evolving rapidly, moving from an agricultural model that emphasized simple stand structures toward a natural disturbance- or ecosystem-based model where stands are managed for multiple species and complex structures. Predicting stand dynamics and future yields in mixed-species complex structured stands cannot be easily accomplished with traditional field experiments. We outline the development and structure of SORTIE/BC, a descendent of the SORTIE model. SORTIE/BC is a light-mediated, spatially explicit, mixed-species forest model that makes population dynamic forecasts for juvenile and adult trees. We use the model to simulate partial cutting prescriptions in temperate deciduous, boreal and temperate coniferous mixed-species forests. The species, amount and spatial pattern of canopy tree removal had a major influence on understory light environments. Low and uniform removal of canopy trees were less successful in favouring the growth and survival of regenerating trees of intermediate to shade intolerant species and the growth of retained canopy trees than patch removal. In the boreal mixedwood, strip-cutting can maintain mixed stands but careful attention must be paid to buffer and strip management to optimize stand growth. We conclude that SORTIE/ BC can be very useful to explore and explain the silvicultural implications of complex silvicultural prescriptions for which there are no existing long-term experiments. © 2003 Elsevier B.V. All rights reserved