Fast switching tunable laser sources for wavelength division multiplexing in passive optical access networks

Tunable laser structures with nanosecond switching time between wavelength channels and low-power injection locking are demonstrated on a low-cost platform. These lasers are suitable as source or slave lasers in WDM passive optical access networks

Assessment of National Natural Resources Policies Implementation in Kilimanjaro Region, Tanzania

The Kilimanjaro landscape provides a range of ecosystem services such as water, local climate modification, tourism and support of local livelihoods. Land degradation has, however, seriously threatened the landscape ability in providing these services, leading to decreased land productivity This paper is based on a study conducted in Kilimanjaro region to provide an understanding of how effectively natural resources-related policies are implemented by land users, and how they practically guide sustainable land management. Data collection involved interviews with purposively selected progressive farmers using a structured questionnaire, in-depth interviews with key informants, mainly district officials, NGOs and CBOs representatives and focus group discussions, as well as review of relevant literature. Quantitative data were analysed using SPSS, while qualitative data were triangulated using content analysis. Findings indicated that there are several policies related to natural resource management that are both cross-cutting and cross-sectoral in nature. While majority of respondents were aware of the various policies, male respondents were more aware than females, influenced by customary male dominance in natural resource issues. The policies are implemented at various levels, taking different forms and involve various stakeholders, including individuals, groups, NGOs, CBOs and public institutions. Generally, communities are actively participating in SLM activities though influenced by several pull and push factors in policy implementation in the area. The paper argues that for effective implementation of the natural resources policies there is a need to review and harmonise the sectoral policies with changing internal and external conditions such as economic transformation, globalization and climate change.

Assessment of the Extent to which Productive Sector Policies Mainstream Sustainable Land Management Principles

This paper provides an assessment of the extent to which productive sector policies mainstream sustainable land management (SLM) principles and suggests how mainstreaming of these principles could be strengthened and be more effective in Kilimanjaro region. Primary data was collected using qualitative methods including in-depth interviews with key informants and focus group discussions. Key informants included government officials, SLM project staff, NGOs and representatives of communities. Secondary data was gathered from review of relevant literature including government policies, strategies, project documents and other research materials. The data collected were analysed using content analysis and synthesised to determine the extent to which the productive sector policies mainstream sustainable land management principles. Findings indicate that several relevant NRM sectors have mainstreamed SLM principles, namely improved land productivity, improved livelihood and improved ecosystems. The degree to which these policies have mainstreamed SLM principles vary from adequately, moderately, and slightly. Despite the reported degree of mainstreaming the SLM principles in sector polices several challenges undermine the process, including land scarcity, land tenure, inadequate enforcement of policies, land use conflicts, human and financial resources constraints, and climate change. Various stakeholders are involved in SLM initiatives, ranging from local communities to international organisations. The diversity of stakeholders requires well coordinated efforts so as to maximise synergies and complementarities between the various actors. Also more effort has to be done at policy level to ensure that all sector policies adequately address sustainability in natural resources management to ensure that land productivity, livelihoods and ecosystems are improved.

The prevalence of gastrointestinal stromal tumour as seen in the Jos University Teaching Hospital (Juth), Jos, North Central Nigeria

Background: Gastrointestinal stromal tumours (GIST) represent 1% of all malignant tumours of the gastrointestinal tract (GIT). However, it is the most common Mesenchymal tumour of the GIT with majority (40 to 60%) arising from the stomach.Objective: To determine the prevalence of GISTamong patients in Jos University Teaching Hospital between 2005 and 2012.Methodology: Five (5) antibodies were used on the Mesenchymal tumours (CD117, CD34, Desmin, SMA and S100). Diagnosis of specific Mesenchymal tumours was based on histological patterns of the tumours on H and E stained slides and immunostaining  characteristics of the tumours.Results: Seven Mesenchymal tumours seen within the study period. This comprises of 6 GIST and 1 Leiomyosarcoma.Conclusions: This study shows that even though GISTis a rare tumour, it is the commonest Mesenchymal tumour of the stomach. It also shows that they are commonly positive for both CD117 and Cd34. Keywords: GIST, Mesenchymal Tumour, Gastrointestinal Tract, Stomac

The relationship between inspiratory lung function parameters and airway hyper-responsiveness in subjects with mild to moderate COPD

Background: The aim of this study was to evaluate the effects of increasing doses of inhaled histamine on the forced expiratory volume in one second (FEV 1), inspiratory lung function parameters (ILPs) and dyspnea in subjects with mild to moderate chronic obstructive pulmonary disease (COPD). Methods. Thirty-nine (27 males and 12 females) stable COPD patients (GOLD stages I and II) inhaled a maximum of six sequential doses of histamine according to ERS standards until one of these provocative doses produced a 20% decrease in FEV 1 (PD 20). The effects on the FEV 1, the forced inspiratory volume in one second (FIV 1), inspiratory capacity (IC), forced inspiratory flow at 50% of the vital capacity (FIF50), peak inspiratory flow (PIF) and dyspnea score by a visual analogue scale (VAS) were measured and investigated after each dose step. Results: After each dose of histamine, declines in all of the lung function parameters were detected; the largest decrease was observed in the FEV 1. At the PD 20 endpoint, more FEV 1 responders than ILP responders were found. Among the ILPs, the FIV 1 and IC best predicted which patients would reach the PD 20 endpoint. No significant correlations were found between any of the lung function parameters and the VAS results. Conclusions: In COPD patients, the FEV 1 and ILPs declined after each dose of inhaled histamine. FEV 1 was more sensitive to histamine than the ILPs. Of the ILPs, FIV 1 and IC were the best predictors of reaching the PD 20 endpoint. No statistically significant correlations were found between the lung function parameters and the degree of dyspnea

Role of Human-Induced Pluripotent Stem Cell-Derived Spinal Cord Astrocytes in the Functional Maturation of Motor Neurons in a Multielectrode Array System

The ability to generate human-induced pluripotent stem cell (hiPSC)-derived neural cells displaying region-specific phenotypes is of particular interest for modeling central nervous system biology in vitro. We describe a unique method by which spinal cord hiPSC-derived astrocytes (hiPSC-A) are cultured with spinal cord hiPSC-derived motor neurons (hiPSC-MN) in a multielectrode array (MEA) system to record electrophysiological activity over time. We show that hiPSC-A enhance hiPSC-MN electrophysiological maturation in a time-dependent fashion. The sequence of plating, density, and age in which hiPSC-A are cocultured with MN, but not their respective hiPSC line origin, are factors that influence neuronal electrophysiology. When compared to coculture with mouse primary spinal cord astrocytes, we observe an earlier and more robust electrophysiological maturation in the fully human cultures, suggesting that the human origin is relevant to the recapitulation of astrocyte/motor neuron crosstalk. Finally, we test pharmacological compounds on our MEA platform and observe changes in electrophysiological activity, which confirm hiPSC-MN maturation. These findings are supported by immunocytochemistry and real-time PCR studies in parallel cultures demonstrating human astrocyte mediated changes in the structural maturation and protein expression profiles of the neurons. Interestingly, this relationship is reciprocal and coculture with neurons influences astrocyte maturation as well. Taken together, these data indicate that in a human in vitro spinal cord culture system, astrocytes support hiPSC-MN maturation in a time-dependent and species-specific manner and suggest a closer approximation of in vivo conditions

Telomere-based proliferative lifespan barriers in Werner-syndrome fibroblasts involve both p53-dependent and p53-independent mechanisms

Werner-syndrome fibroblasts have a reduced in vitro life span before entering replicative senescence. Although this has been thought to be causal in the accelerated ageing of this disease, controversy remains as to whether Werner syndrome is showing the acceleration of a normal cellular ageing mechanism or the occurrence of a novel Werner-syndrome-specific process. Here, we analyse the signalling pathways responsible for senescence in Werner-syndrome fibroblasts. Cultured Werner-syndrome (AG05229) fibroblasts senesced after approximately 20 population doublings with most of the cells having a 2N content of DNA. This was associated with hypophosphorylated pRb and high levels of p16(Ink4a) and p21(Waf1). Senescent AG05229 cells re-entered the cell cycle following microinjection of a p53-neutralizing antibody. Similarly, production of the human papilloma virus 16 E6 oncoprotein in presenescent AG05229 cells resulted in senescence being bypassed and extended cellular life span. Werner-syndrome fibroblasts expressing E6 did not proliferate indefinitely but reached a second proliferative lifespan barrier, termed M(int), that could be bypassed by forced production of telomerase in post-M1 E6-producing cells. The conclusions from these studies are that: (1) replicative senescence in Werner-syndrome fibroblasts is a telomere-induced p53-dependent event; and (2) the intermediate lifespan barrier M(int) is also a telomere-induced event, although it appears to be independent of p53. Werner-syndrome fibroblasts resemble normal human fibroblasts for both these proliferative lifespan barriers, with the strong similarity between the signalling pathway linking telomeres to cell-cycle arrest in Werner-syndrome and normal fibroblasts providing further support for the defect in Werner syndrome causing the acceleration of a normal ageing mechanism

The Tchebyshev transforms of the first and second kind

We give an in-depth study of the Tchebyshev transforms of the first and second kind of a poset, recently discovered by Hetyei. The Tchebyshev transform (of the first kind) preserves desirable combinatorial properties, including Eulerianess (due to Hetyei) and EL-shellability. It is also a linear transformation on flag vectors. When restricted to Eulerian posets, it corresponds to the Billera, Ehrenborg and Readdy omega map of oriented matroids. One consequence is that nonnegativity of the cd-index is maintained. The Tchebyshev transform of the second kind is a Hopf algebra endomorphism on the space of quasisymmetric functions QSym. It coincides with Stembridge's peak enumerator for Eulerian posets, but differs for general posets. The complete spectrum is determined, generalizing work of Billera, Hsiao and van Willigenburg. The type B quasisymmetric function of a poset is introduced. Like Ehrenborg's classical quasisymmetric function of a poset, this map is a comodule morphism with respect to the quasisymmetric functions QSym. Similarities among the omega map, Ehrenborg's r-signed Birkhoff transform, and the Tchebyshev transforms motivate a general study of chain maps. One such occurrence, the chain map of the second kind, is a Hopf algebra endomorphism on the quasisymmetric functions QSym and is an instance of Aguiar, Bergeron and Sottile's result on the terminal object in the category of combinatorial Hopf algebras. In contrast, the chain map of the first kind is both an algebra map and a comodule endomorphism on the type B quasisymmetric functions BQSym.Comment: 33 page

Dynamics of senescence-related QTLs in potato

The study of quantitative trait's expression over time helps to understand developmental processes which occur in the course of the growing season. Temperature and other environmental factors play an important role. The dynamics of haulm senescence was observed in a diploid potato mapping population in two consecutive years (2004 and 2005) under field conditions in Finland. The available time series data were used in a smoothed generalized linear model to characterize curves describing the senescence development in terms of its onset, mean and maximum progression rate and inflection point. These characteristics together with the individual time points were used in a Quantitative trait loci (QTL) analysis. Although QTLs occurring early in the sene

Affine and toric hyperplane arrangements

We extend the Billera-Ehrenborg-Readdy map between the intersection lattice and face lattice of a central hyperplane arrangement to affine and toric hyperplane arrangements. For arrangements on the torus, we also generalize Zaslavsky's fundamental results on the number of regions.Comment: 32 pages, 4 figure