Determining Energy Balance in the Flaring Chromosphere from Oxygen V Line Ratios

The impulsive phase of solar flares is a time of rapid energy deposition and heating in the lower solar atmosphere, leading to changes in the temperature and density structure of the region. We use an O V density diagnostic formed of the 192 to 248 line ratio, provided by Hinode EIS, to determine the density of flare footpoint plasma, at O V formation temperatures of 250,000 K, giving a constraint on the properties of the heated transition region. Hinode EIS rasters from 2 small flare events in December 2007 were used. Raster images were co-aligned to identify and establish the footpoint pixels, multiple-component Gaussian line fitting of the spectra was carried out to isolate the diagnostic pair, and the density was calculated for several footpoint areas. The assumptions of equilibrium ionization and optically thin radiation for the O V lines were found to be acceptable. Properties of the electron distribution, for one event, were deduced from earlier RHESSI hard X-ray observations and used to calculate the plasma heating rate, delivered by an electron beam adopting collisional thick-target assumptions, for 2 model atmospheres. Electron number densities of at least log n = 12.3 cm-3 were measured during the flare impulsive phase, far higher than previously expected. For one footpoint, the radiative loss rate for this plasma was found to exceed that which can be delivered by an electron beam implied by the RHESSI data. However, when assuming a completely ionised target atmosphere the heating rate exceeded the losses. A chromospheric thickness of 70-700 km was found to be required to balance a conductive input to the O V-emitting region with radiative losses. The analysis shows that for heating by collisional electrons, it is difficult, or impossible to raise the temperature of the chromosphere to explain the observed densities without assuming a completely ionised atmosphere.Comment: Accepted to A&A 14th September 201

Observations and Modelling of Helium Lines in Solar Flares

We explore the response of the He II 304 Å and He I 584 Å line intensities to electron beam heating in solar flares using radiative hydrodynamic simulations. Comparing different electron beams parameters, we found that the intensities of both He lines are very sensitive to the energy flux deposited in the chromosphere, or more specifically to the heating rate, with He II 304 {\AA} being more sensitive to the heating than He I 584 {\AA}. Therefore, the He line ratio increases for larger heating rates in the chromosphere. A similar trend is found in observations, using SDO/EVE He irradiance ratios and estimates of the electron beam energy rate obtained from hard X-ray data. From the simulations, we also found that spectral index of the electrons can affect the He ratio but a similar effect was not found in the observations

The Fundamental Properties of Dwarf Elliptical Galaxies in Clusters

We present preliminary results of an extensive study of the fundamental properties of dwarf elliptical galaxies (dEs) in the Coma cluster. Our study will combine HST surface photometry with ground-based UBRIJK photometry and optical spectroscopy. The combined data set will be used to investigate the intrinsic correlations among global parameters in cluster dEs, including the Fundamental Plane, the color-magnitude relation, the Faber-Jackson and Kormendy relation, and velocity dispersion versus line strength indices. These empirical correlations have provided important constraints to theoretical models of galaxy formation and evolution for "normal" elliptical galaxies. Although dEs are the most abundant galaxy population in clusters their properties remain, however, largely unknown. Our study aims to provide an essential reference for testing current theories on the formation and evolution of dEs in clusters, and understanding their relation to more massive elliptical galaxies.Comment: 10 pages. To appear in "Star Formation through Time", 2003, ASP Conf. Ser. ed. Perez, Gonzalez Delgado, Tenorio-Tagl

The Internet and Business Process Outsourcing in East Africa: Value Chains and Networks of Connectivity-Based Enterprises in Kenya and Rwanda

Internet connectivity is widely considered to be a game changer for knowledge economies of developing countries. The arrival of submarine fibre-optic underwater cables in East Africa in 2009 and 2010 is seen by many as a strong case in point. The fast evolution of the information and communication technology (ICT) landscape of Kenya and Rwanda that ensued has attracted the attention of actors from private investors, development agencies, NGOs, policymakers and many other groups. Kenya became a role model for its wide-spread adoption of mobile money services and a burgeoning ICT application development sector; Rwanda’s government became known for its explicitly ICT-oriented development agenda as well as large-scale ICT projects in government, health and education that aimed to latch onto fast-growing mobile subscription rates and 3G network roll-outs. For this report, we set out to examine the role that changing connectivity has played for a particular component of the ICT sector in Kenya and Rwanda: ICT-enabled business process outsourcing (BPO). BPO has been a priority in the national ICT strategies of both countries, so we anticipated this sector to provide a fertile ground for comparing expectations and practices of the roles that changing connectivity has played following the deployment of fibre-optic cable infrastructure. BPO is also an interesting sector because internet connectivity is at the heart of its value chain: At first glance, fast internet connections should go a long way in bridging geographical distance and enabling Kenyan and Rwandan businesses to tap into continuously growing BPO demand from all over the world. BPO is also inherently a global, or at least a widely geographically distributed, industry. Our analysis was therefore designed to shed light on the risks and opportunities of establishing connectivity-based local sectors that are bound to be exposed to international markets and competition. However, the development of ICT sectors fell short of many original hopes. Internet connectivity proved to only function as a catalyst for economic growth in combination with other enablers. Competitive advantage is always relative, and, in the case of Kenya’s and Rwanda’s BPO sectors, India and other Asian BPO destinations have maintained the edge in international markets. Despite the overall positive evolution of ICT-based subsectors in Kenya and Rwanda, the role of internet connectivity for growth in knowledge economies continues to be a complicated one, including for connectivity-based enterprises. Future opportunities might actually lie in ‘close’ (local and regional) markets, and policymakers (and indeed all economic actors) will need to continue to learn and adjust to other unexpected developments brought about by internet connectivity

Digital Entrepreneurship in Africa

The hope and hype about African digital entrepreneurship, contrasted with the reality on the ground in local ecosystems. In recent years, Africa has seen a digital entrepreneurship boom, with hundreds of millions of dollars poured into tech cities, entrepreneurship trainings, coworking spaces, innovation prizes, and investment funds. Politicians and technologists have offered Silicon Valley–influenced narratives of boundless opportunity and exponential growth, in which internet-enabled entrepreneurship allows Africa to “leapfrog” developmental stages to take a leading role in the digital revolution. This book contrasts these aspirations with empirical research about what is actually happening on the ground. The authors find that although the digital revolution has empowered local entrepreneurs, it does not untether local economies from the continent's structural legacies. Drawing on a five-year research project, the authors show how entrepreneurs creatively and productively adapt digital technologies to local markets rather than dreaming of global dominance, achieving sustainable businesses by scaling based on relationships and customizing digital platform business models for African infrastructure challenges. The authors examine African entrepreneurial ecosystems; show that African digital entrepreneurs have begun to form a new professional class, becoming part of a relatively exclusive cultural and economic elite; and discuss the impact of Silicon Valley's mythologies and expectations. Finally, they consider the implications of their findings and offer recommendations to policymakers and others

The Internet and Business Process Outsourcing in East Africa: Value Chains and Networks of Connectivity-Based Enterprises in Kenya and Rwanda

Internet connectivity is widely considered to be a game changer for knowledge economies of developing countries. The arrival of submarine fibre-optic underwater cables in East Africa in 2009 and 2010 is seen by many as a strong case in point. The fast evolution of the information and communication technology (ICT) landscape of Kenya and Rwanda that ensued has attracted the attention of actors from private investors, development agencies, NGOs, policymakers and many other groups. Kenya became a role model for its wide-spread adoption of mobile money services and a burgeoning ICT application development sector; Rwanda’s government became known for its explicitly ICT-oriented development agenda as well as large-scale ICT projects in government, health and education that aimed to latch onto fast-growing mobile subscription rates and 3G network roll-outs. For this report, we set out to examine the role that changing connectivity has played for a particular component of the ICT sector in Kenya and Rwanda: ICT-enabled business process outsourcing (BPO). BPO has been a priority in the national ICT strategies of both countries, so we anticipated this sector to provide a fertile ground for comparing expectations and practices of the roles that changing connectivity has played following the deployment of fibre-optic cable infrastructure. BPO is also an interesting sector because internet connectivity is at the heart of its value chain: At first glance, fast internet connections should go a long way in bridging geographical distance and enabling Kenyan and Rwandan businesses to tap into continuously growing BPO demand from all over the world. BPO is also inherently a global, or at least a widely geographically distributed, industry. Our analysis was therefore designed to shed light on the risks and opportunities of establishing connectivity-based local sectors that are bound to be exposed to international markets and competition. However, the development of ICT sectors fell short of many original hopes. Internet connectivity proved to only function as a catalyst for economic growth in combination with other enablers. Competitive advantage is always relative, and, in the case of Kenya’s and Rwanda’s BPO sectors, India and other Asian BPO destinations have maintained the edge in international markets. Despite the overall positive evolution of ICT-based subsectors in Kenya and Rwanda, the role of internet connectivity for growth in knowledge economies continues to be a complicated one, including for connectivity-based enterprises. Future opportunities might actually lie in ‘close’ (local and regional) markets, and policymakers (and indeed all economic actors) will need to continue to learn and adjust to other unexpected developments brought about by internet connectivity

Modeling of the hydrogen Lyman lines in solar flares

The hydrogen Lyman lines (91.2 nm < λ < 121.6 nm) are significant contributors to the radiative losses of the solar chromosphere, and they are enhanced during flares. We have shown previously that the Lyman lines observed by the Extreme Ultraviolet Variability instrument onboard the Solar Dynamics Observatory exhibit Doppler motions equivalent to speeds on the order of 30 km s−1. However, contrary to expectations, both redshifts and blueshifts were present and no dominant flow direction was observed. To understand the formation of the Lyman lines, particularly their Doppler motions, we have used the radiative hydrodynamic code, RADYN, along with the radiative transfer code, RH, to simulate the evolution of the flaring chromosphere and the response of the Lyman lines during solar flares. We find that upflows in the simulated atmospheres lead to blueshifts in the line cores, which exhibit central reversals. We then model the effects of the instrument on the profiles, using the Extreme Ultraviolet Variability Experiment (EVE) instrument's properties. What may be interpreted as downflows (redshifted emission) in the lines, after they have been convolved with the instrumental line profile, may not necessarily correspond to actual downflows. Dynamic features in the atmosphere can introduce complex features in the line profiles that will not be detected by instruments with the spectral resolution of EVE, but which leave more of a signature at the resolution of the Spectral Investigation of the Coronal Environment instrument onboard the Solar Orbiter

Carbon Capital’s Political Reach: A Network Analysis Of Federal Lobbying By The Fossil Fuel Industry From Harper To Trudeau

This paper provides a network analysis of federal lobbying in Canada by the fossil fuel industry over a seven-year period from January 4, 2011 to January 30, 2018, enabling a comparative examination of lobbying under the Harper Conservatives and the Trudeau Liberals. The network we uncover amounts to ‘small world’ of intense interaction among relatively few lobbyists/firms that control much of this economic sector and the designated public office holders in select centres of state power, who are their targets. In comparing lobbying across the Harper and Trudeau administrations, we find a pattern of continuity-in-change: under Trudeau, the bulk of lobbying has been carried out by the same large firms as under Harper, while the lobbying network has become more focused on fewer state agencies. We argue that the strategic, organized, and sustained lobbying efforts of the fossil fuel sector help to explain the close coupling of federal policy to the needs of carbon extractive corporations