Transit times through the cycle phases of jejunal crypt cells of the mouse

Mean transit times as well as variances of the transit times through the individual phases of the cell cycle have been determined for the crypt epithelial cells of the jejunum of the mouse. To achieve this the fraction of labelled mitoses (FLM) technique has been modified by double labelling with [3H] and [14C]thymidine. Mice were given a first injection of [3H]thymidine, and 2 hr later a second injection of [14C]thymidine. This produces a narrow subpopulation of purely 3H-labelled cells at the beginning of G2-phase and a corresponding subpopulation of purely 14C-labelled cells at the beginning of the S-phase. When these two subpopulations progress through the cell cycle, one obtains FLM waves of purely 3H- and purely 14C-labelled mitoses. These waves have considerably better resolution than the conventional FLM-curves. From the temporal positions of the observed maxima the mean transit times of the cells through the individual phases of the cycle can be determined. Moreover one obtains from the width of the individual waves the variances of the transit times through the individual phases. It has been found, that the variances of the transit times through successive phases are additive. This indicates that the transit times of cells through successive phases are independently distributed. This statistical independence is an implicit assumption in most of the models applied to the analysis of FLM curves, however there had previously been no experimental support of this assumption. A further result is, that the variance of the transit time through any phase of the cycle is proportional to the mean transit time. This implies that the progress of the crypt epithelial cells is subject to an equal degree of randomness in the various phases of the cycle

Concepts and Actors in Organic Livestock Husbandry in Bolivia

Traditional smallholder livestock production is expected to correspond widely with principles of organic livestock farming. Though, the real magnitude of livestock under organic and alike management is unknown. From stakeholder analysis and structured interviews with key persons in Bolivia it is deduced that similarities are widely given, whereas it is questioned whether a formal individual certification approach for livestock products will match the farmer interests and consumer demands

Dichroic atomic vapor laser lock with multi-gigahertz stabilization range

A dichroic atomic vapor laser lock (DAVLL) system exploiting buffer-gas-filled millimeter-scale vapor cells is presented. This system offers similar stability as achievable with conventional DAVLL system using bulk vapor cells, but has several important advantages. In addition to its compactness, it may provide continuous stabilization in a multi-gigahertz range around the optical transition. This range may be controlled either by changing the temperature of the vapor or by application of a buffer gas under an appropriate pressure. In particular, we experimentally demonstrate the ability of the system to lock the laser frequency between two hyperfine components of the $^{85}$Rb ground state or as far as 16 GHz away from the closest optical transition.Comment: 11 pages, 7 figures. Published in Review of Scientific Instruments 201

Mitigating 'Non-Conflict' Violence by Creating Peaceful Political Settlements

Understanding and addressing ‘non-conflict’ violence is a key challenge for development. Different types of ‘non-conflict’ violence, such as homicide, massacres, armed robbery and gender-based violence, which occur outside of armed conflict contexts involving state or other parties, are not only reflections of social problems like youth unemployment and gang culture. They should not be unlinked from political processes. Given the weakness of formal institutions and the strength of hybrid political orders in most violence-affected settings in the developing world, the political settlements approach helps to understand the political factors that underpin and drive ‘non-conflict’ violence; and develop policy responses that tackle the roots of the problem, not just its symptoms.UK Department for International Developmen

Getting Real About an Illicit ‘External Stressor’: Transnational Cocaine Trafficking through West Africa

Concerns over West Africa’s increasingly prominent role as transhipment point of South American cocaine en route to Europe are mounting. Gathering pace in the mid-2000s, large-scale drug trafficking has been associated with recent episodes of political instability and violence in Guinea-Bissau, Guinea and Mali. It is also perceived as a serious threat to democratic institutions, governance and development in other, more stable countries of the region, such as Ghana; and as potentially contributing to reversing the hard-won end to the armed conflicts that ravaged Sierra Leone, Liberia, Guinea-Bissau and Côte d’Ivoire in the 1990s and 2000s. Yet it is crucial to recognise that cocaine trafficking through West Africa has thus far not resulted in levels of violence comparable to those witnessed in several Latin American drug source and transit countries. The big policy challenge for West Africa is therefore not to curb the flow of cocaine through the region in order to reduce trafficking-related violence, but to effectively tackle the negative impacts – both existing and potential – of the illegal trade on governance and development in the region’s weak, unstable and impoverished states. Conventional drug control strategies, oriented towards law enforcement, are not well suited to help with this. Bold new policy responses are called for.UK Department for International Developmen

The Effects of Interpersonal and Informational Justice on Perceptions of an Authority Figure

There are several traits and characteristics that people may use to judge an authority based on how that authority acts and treats those under him or her. However, are there times when an authority can influence his or her own reputation among subordinates simply by the type of task he or she provides, or the level of information he or she presents? Prior evidence has suggested that perceptions of authorities are influenced by a number of qualities. The purpose of this experiment was to test how the nature of a task and whether a rationale is provided for the task will affect the perception of interpersonal and informational fairness in relation to an authority figure. The findings suggest that authorities are indeed judged by the tasks they present and whether a rationale is given to explain those tasks

Core Collection Approaches and Genetic Diversity in \u3ci\u3eFlemingia macrophylla\u3c/i\u3e

Core collections are a useful means to optimise the management, including conservation, of forage germplasm collections. Such optimisation is warranted in view of increasingly limited research resources. As there are several potential options to create core collections, a project is presented in which three approaches are compared: (i) based on germplasm origin information; (ii) genetic diversity assessment by agronomic characterisation/evaluation; and (iii) DNA markers. As example-species for the project, the tropical legume shrub Flemingia macrophylla is selected because of its particular multiple-use potential in smallholder production systems. An important diversity descriptor is the content of tannins influencing feed and litter quality of this species. Data will be analysed using multivariate statistics and GIS tools. The results from the core collection approach comparison are expected to be applicable also to other wild legumes

Toward Effective Violence Mitigation: Transforming Political Settlements

Recognising the centrality of violence in the development process (though not subscribing to the notion that conflict and violence are development in reverse), in 2012–14 a group of researchers at the Institute of Development Studies (IDS) engaged in depth with the complex and thorny questions of how ‘new’ forms of violence in the developing world – as opposed to ‘traditional’ civil or intra-state war – should be understood; and through which policies they could best be prevented and/or mitigated. The result of this endeavour is a series of evidence-based reports that were produced in collaboration with Southern partners in a sample of four violence-affected countries in Africa: Nigeria (Niger Delta), Sierra Leone, Egypt and Kenya (Marsabit County). The evidence from the four case studies suggests that – contrary to the early post-Cold War accounts of ‘barbarism’ and ‘senseless bloodshed’ – the violence we observe in many countries and locales today is about something. Yet, the analyses also show that the triggers, manifestations and effects of this violence – characterised as diffuse, recursive and globalised – cannot be captured by using the analytical tools developed to explain armed conflict within states. Strictly speaking, it would be misguided to label the violence in the Niger Delta, Marsabit County, Egypt and Sierra Leone as ‘civil war’, ‘internal armed conflict’ or ‘new war’. Instead, it is more accurate to speak of highly heterogeneous situations of violence or ‘fields of social violence’. At the same time, it is crucial not to dissociate these situations of violence from political processes by, for instance, reducing them to manifestations of criminality, such as homicide and illicit drug trafficking, or reflections of social problems like rampant youth unemployment, the use of prohibited psychoactive substances, and gang culture.UK Department for International Developmen

Automated quantitative analysis of single and double label autoradiographs

A method for the analysis of silver grain content in both single and double label autoradiographs is presented. The total grain area is calculated by counting the number of pixels at which the recorded light intensity in transmission dark field illumination exceeds a selected threshold. The calibration tests included autoradiographs with low (3H- thymidin) and high (3H-desoxyuridin) silver grain density. The results are proportional to the customary visual grain count. For the range of visibly countable grain densities in single labeled specimens, the correlation coefficient between the computed values and the visual grain counts is better than 0.96. In the first emulsion of the two emulsion layer autoradiographs of double labeled specimens (3H-14C- thymidin) the correlation coefficient is 0.919 and 0.906. The method provides a statistical correction for the background grains not due to the isotope. The possibility to record 14C tracks by shifting the focus through the second emulsion of the double labeled specimens is also demonstrated. The reported technique is essentially independent of size, shape and density of the grains