20,514 research outputs found
The effect of environmental variability on livestock and land-use management: The Borana plateau, southern Ethiopia
The Borana people are the predominant ethnic group on the Borana Plateau in southern Ethiopia. Though traditionally transhumant pastoralists, they have recently increased their reliance on crops. Rainfall in the region averages between 353 mm to 873 mm; variability in rainfall is quite high, with coefficients of variation ranging from.21 to.68. The past decade has witnessed a dramatic increase in land allocated to crops, and land in pastures that are either becoming privatised, or accessible to only a small sub-group of people. In this paper, we derive an empirical model of stocking rates and land allocation, which is then used to estimate the effects of exogenous parameters on stocking densities, land allocated to crops, and land allocated to private pastures. Results indicate the following: a) regions with high coefficients of variation in rainfall have lower livestock densities and less land allocated to crops, b) communities with greater numbers of households and higher population densities have larger indices of non-cooperation, higher stock densities, and more land allocated to crops, c) heterogeneity within a community, measured by the distribution of wealth levels, is positively related to an index of non-cooperation, and to higher stock densities, d) higher relative prices of livestock and shorter distances to market are associated with greater stock densities as well as greater land allocated to crops, e) the greater is mobility into an area, the higher are stock densities, and the lower is the cooperation level, whereas outward mobility by community members has no effect on either stock densities or the level of cooperation reached, f) the proportion of members engaged in wage work outside has a significant negative effect on the ability of the community to cooperate. Outside wage work also increases land allocated to crops, but has a significant negative effect on land allocated to private pastures, and g) the greater is the index of non-cooperation, the higher are stock densities and the greater is land allocated to crops.
The increasing likelihood of temperatures above 30 to 40 °C in the United Kingdom
This is the final version. Available on open access from Nature Research via the DOI in this recordData availability:
The HadUK-Grid temperature data and station temperature data from the Met Office Integrated Data Archive System (MIDAS) that support the findings of this study are available from the CEDA Archive, http://archive.ceda.ac.uk. The CMIP5 simulated temperature data that support the findings of this study are available from the Earth System Grid Federation (ESGF) Archive, https://esgf.llnl.gov/.Code availability:
IDL code used for the analysis is available upon request.As European heatwaves become more severe, summers in the United Kingdom (UK) are also getting warmer. The UK record temperature of 38.7 °C set in Cambridge in July 2019 prompts the question of whether exceeding 40 °C is now within reach. Here, we show how human influence is increasing the likelihood of exceeding 30, 35 and 40 °C locally. We utilise observations to relate local to UK mean extremes and apply the resulting relationships to climate model data in a risk-based attribution methodology. We find that temperatures above 35 °C are becoming increasingly common in the southeast, while by 2100 many areas in the north are likely to exceed 30 °C at least once per decade. Summers which see days above 40 °C somewhere in the UK have a return time of 100-300 years at present, but, without mitigating greenhouse gas emissions, this can decrease to 3.5 years by 2100.Met Office Hadley Centre Climate Programm
miR-375 gene dosage in pancreatic β-cells: implications for regulation of β-cell mass and biomarker development
MicroRNAs play a crucial role in the regulation of cell growth and differentiation. Mice with genetic deletion of miR-375 exhibit impaired glycemic control due to decreased β-cell and increased α-cell mass and function. The relative importance of these processes for the overall phenotype of miR-375KO mice is unknown. Here, we show that mice overexpressing miR-375 exhibit normal β-cell mass and function. Selective re-expression of miR-375 in β-cells of miR-375KO mice normalizes both, α- and β-cell phenotypes as well as glucose metabolism. Using this model, we also analyzed the contribution of β-cells to the total plasma miR-375 levels. Only a small proportion (≈1 %) of circulating miR-375 originates from β-cells. Furthermore, acute and profound β-cell destruction is sufficient to detect elevations of miR-375 levels in the blood. These findings are supported by higher miR-375 levels in the circulation of type 1 diabetes (T1D) subjects but not mature onset diabetes of the young (MODY) and type 2 diabetes (T2D) patients. Together, our data support an essential role for miR-375 in the maintenance of β-cell mass and provide in vivo evidence for release of miRNAs from pancreatic β-cells. The small contribution of β-cells to total plasma miR-375 levels make this miRNA an unlikely biomarker for β-cell function but suggests a utility for the detection of acute β-cell death for autoimmune diabetes
Optimality Theory as a Framework for Lexical Acquisition
This paper re-investigates a lexical acquisition system initially developed
for French.We show that, interestingly, the architecture of the system
reproduces and implements the main components of Optimality Theory. However, we
formulate the hypothesis that some of its limitations are mainly due to a poor
representation of the constraints used. Finally, we show how a better
representation of the constraints used would yield better results
Artificial Intelligence
Contains reports on four research projects.M.I.T. Research Laboratory of ElectronicsM.I.T. Computation Cente
The Error in Trial and Error: Exercises on Phrasal Verbs
An analysis of 44 commercially available EFL textbooks found that it is common for textbooks to present learners with exercises on phrasal verbs without first providing relevant input to help them. In these cases, the learners are likely to resort to trial-and-error and are then expected to learn from feedback. We report an experiment conducted with Japanese EFL students (N=140) in which we compare the effectiveness of such a trial-and-error method with a retrieval procedure in which students first study a set of phrasal verbs and then complete an exercise. Scores on both an immediate and a one-week delayed post-test suggest superiority of retrieval over the trial-and-error procedure, where, despite the provision of feedback, 25% of the wrong exercise responses were reproduced in the delayed post-test
Dust-forming molecules in VY Canis Majoris (and Betelgeuse)
The formation of inorganic dust in circumstellar environments of evolved
stars is poorly understood. Spectra of molecules thought to be most important
for the nucleation, i.e. AlO, TiO, and TiO2, have been recently detected in the
red supergiant VY CMa. These molecules are effectively formed in VY CMa and the
observations suggest that non-equilibrium chemistry must be involved in their
formation and nucleation into dust. In addition to exploring the recent
observations of VY CMa, we briefly discuss the possibility of detecting these
molecules in the dust-poor circumstellar environment of Betelgeuse.Comment: contribution to Betelgeuse Workshop 2012: "The physics of Red
Supergiants: recent advances and open questions", 26-29 Nov 2012 Paris
(France
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