| 1. |
- Alberts, Susan C., et al.
(författare)
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Reproductive aging patterns in primates reveal that humans are distinct
- 2013
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 110:33, s. 13440-13445
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Tidskriftsartikel (refereegranskat)abstract
- Women rarely give birth after similar to 45 y of age, and they experience the cessation of reproductive cycles, menopause, at similar to 50 y of age after a fertility decline lasting almost two decades. Such reproductive senescence in mid-lifespan is an evolutionary puzzle of enduring interest because it should be inherently disadvantageous. Furthermore, comparative data on reproductive senescence from other primates, or indeed other mammals, remains relatively rare. Here we carried out a unique detailed comparative study of reproductive senescence in seven species of nonhuman primates in natural populations, using long-term, individual-based data, and compared them to a population of humans experiencing natural fertility and mortality. In four of seven primate species we found that reproductive senescence occurred before death only in a small minority of individuals. In three primate species we found evidence of reproductive senescence that accelerated throughout adulthood; however, its initial rate was much lower than mortality, so that relatively few individuals experienced reproductive senescence before death. In contrast, the human population showed the predicted and well-known pattern in which reproductive senescence occurred before death for many women and its rate accelerated throughout adulthood. These results provide strong support for the hypothesis that reproductive senescence in midlife, although apparent in natural-fertility, natural-mortality populations of humans, is generally absent in other primates living in such populations.
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| 2. |
- Alberts, D., et al.
(författare)
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In-depth profile analysis of filled alumina and titania nanostructured templates by radiofrequency glow discharge coupled to optical emission spectrometry
- 2010
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Ingår i: Analytical and Bioanalytical Chemistry. - : Springer Science and Business Media LLC. - 1618-2642 .- 1618-2650. ; 396:8, s. 2833-2840
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Tidskriftsartikel (refereegranskat)abstract
- The development of highly ordered and self-assembled magnetic nanostructures such as arrays of Fe or Ni nanowires and their alloys is arousing increasing interest due to the peculiar magnetic properties of such materials at the nanoscale. These nanostructures can be fabricated using nanoporous anodic alumina membranes or self-assembled nanotubular titanium dioxide as templates. The chemical characterization of the nanostructured layers is of great importance to assist the optimization of the filling procedure or to determine their manufacturing quality. Radiofrequency glow discharge (RF-GD) coupled to optical emission spectrometry (OES) is a powerful tool for the direct analysis of either conducting or insulating materials and to carry out depth profile analysis of thin layers by multi-matrix calibration procedures. Thus, the capability of RF-GD-OES is investigated here for the in-depth quantitative analysis of self-aligned titania nanotubes and self-ordered nanoporous alumina filled with arrays of metallic and magnetic nanowires obtained using the template-assisted filling method. The samples analysed in this work consisted of arrays of Ni nanowires with different lengths (from 1.2 up to 5 μm) and multilayer nanowires of alternating layers with different thicknesses (of 1-2 μm) of Ni and Au, or Au and FeNi alloy, deposited inside the alumina and titania membranes. Results, compared with other techniques such as scanning electron microscopy and energy-dispersive X-ray spectroscopy, show that the RF-GD-OES surface analysis technique proves to be adequate and promising for this challenging application. © 2009 Springer-Verlag.
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| 3. |
- Barnes, J. I., et al.
(författare)
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Expected climate change impacts on land and natural resource use in Namibia: exploring economically efficient responses
- 2012
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Ingår i: Pastoralism: Research, Policy and Practice. - : Springer Science and Business Media LLC. - 2041-7128 .- 2041-7136. ; 2:1
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Tidskriftsartikel (refereegranskat)abstract
- This paper informs policy over the efficiency of investments on Namibia's rangelands both now and under future expected climate change. It is in this setting that Namibia's pastoralist communities, communal conservancies and increasing numbers of wildlife reside, and their economic activity dominates. We bring the principles of economics to decision-making. We analyse primary land uses, livestock production and wildlife viewing tourism in three ecologically different biomes - the southern Karoo Biome, the central Savanna Biome and the northeastern Woodland Biome. We analyse how expected climate change will impact these investments to 2080. From an economic perspective, pastoralism and wildlife-based tourism developed within common property management systems can be sound investments across Namibia's communal lands. Furthermore, as climate changes, the existing economic benefits to the Namibian economy associated with pastoralism and wildlife-based tourism should be magnified, as capital-intensive commercial fenced ranching systems become less economic. Recent research indicates that adoption of good rangeland management principles involving flexible herding, economies of scale and commercially viable utilisation of invasive bush can significantly increase profits and economic returns on investment for livestock systems in Namibia. Furthermore, under conditions of expected climate change, our results indicate that income from natural resource use will be more resilient than livestock and other agricultural investments. Estimated losses in economic contribution will be highest in the agricultural sector, and in particular with commercial fenced ranching, and rainfed cropping. Climate change poses considerable challenges for pastoralists and other economic activity on Namibia's rangelands. Global climate modelling suggests that by 2080, Namibia's temperatures will have increased by some 3°C and rainfall decreased by 5% to 20%. Our results suggest that gradual change in climate over the next 70 years will see the potential national value of livestock income halved and that of tourism income reduced by one quarter. Active interventions should include shifts in livestock and rangeland policy, encouraging the adoption of more flexible and resilient systems and including efforts to make rangeland use less rigid and more able to change and adapt. Adaptation to climate change should include promotion of natural resource-based land uses such as continued expansion of the Community Based Natural Resource Management programme. Furthermore, national policy now recognises this, and implementation of the Namibia Rangeland Management Policy will provide incentives to invest in sound rangeland management. © 2012, Barnes et al.; licensee Springer.
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| 4. |
- Byass, Peter, et al.
(författare)
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Motherhood, migration and mortality in Dikgale : modelling life events among women in a rural South African community
- 2011
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Ingår i: Public Health. - London : Academic P.. - 0033-3506 .- 1476-5616. ; 125:5, s. 318-323
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Although particular types of life events in populations are often studied separately, this study investigated the joint effects of three major event types in South African women’s lives: motherhood, migration and mortality. Study design: Data were taken from a health and demographic surveillance site (HDSS) over an 11-year period, reflecting the entire population of a defined geographic area as an open cohort, in which individuals participated in regular longitudinal surveillance for health and demographic events. This HDSS is a member of the Indepth Network. Methods: Multivariate Poisson regression models were built for each of the three life event types, in which individual person-time observed out of the total possible 11-year period was used as a rate multiplier. These models were used to calculate adjusted incidence rate ratios for each factor. Results: In the 21,587 person–years observed for women aged 15–49 years, from 1996 to 2006, adjusted rate ratios for mortality and migration increased substantially over time, while motherhood remained fairly constant. Women who migrated were less likely to bear children; temporary migrants were at greater risk of dying, while permanent in-migrants had higher survival rates. Women who subsequently died were much less likely to bear children or migrate. Conclusions: The associations between motherhood, migration and mortality among these rural South African women were complex and dynamic. Extremely rapid increases in mortality over the period studied are presumed to reflect the effects of the human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) epidemic. Understanding these complex interactions between various life events at population level is crucial for effective public health planning and service delivery.
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