2,887 research outputs found

    Recalling hydraulic despotism: Hun Sen's Cambodia and the return of strict authoritarianism

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    Mirroring trends elsewhere in Southeast Asia, Cambodia has witnessed a pronounced shift towards stricter authoritarianism over recent years. The state appears more firmly ruled by prime minister Hun Sen than at any time during the past three decades, while the de facto status of the Cambodian People's Party (CPP) more closely resembles the single party regimes of neighboring states. One of the major tools of political control and expansion of authority employed by the hierarchical CPP network is the construction of major infrastructure projects, most notably hydropower dams and irrigation schemes. This article focuses attention on the hydraulic infrastructure aspects of exacting political authority and social control by the elite over the nation, drawing upon Wittfogelian perspectives for a conceptual framework. It maintains that Cambodia increasingly represents a modern variant of a hydraulic society, but primarily functions as a satellite hydraulic state of China. The growing influence of China over Cambodia's hydraulic development has helped elevate Hun Sen to resemble a neo-classic hydraulic despot. Hydraulic society concepts help provide partial understanding of contemporary power relations and party-state ascendency, including the longevity and resilience of Hun Sen's supremacy

    Characterization and Dynamics of Substituted Ruthenacyclobutanes Relevant to the Olefin Cross-Metathesis Reaction

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    The reaction of the phosphonium alkylidene [(H_(2)IMes)RuCl2ā•CHP(Cy)_3)]^(+) BF_(4)^āˆ’ with propene, 1-butene, and 1-hexene at āˆ’45 Ā°C affords various substituted, metathesis-active ruthenacycles. These metallacycles were found to equilibrate over extended reaction times in response to decreases in ethylene concentrations, which favored increased populations of Ī±-monosubstituted and Ī±,Ī±ā€²-disubstituted (both cis and trans) ruthenacycles. On an NMR time scale, rapid chemical exchange was found to preferentially occur between the Ī²-hydrogens of the cis and trans stereoisomers prior to olefin exchange. Exchange on an NMR time scale was also observed between the Ī±- and Ī²-methylene groups of the monosubstituted ruthenacycle (H_(2)IMes)Cl_(2)Ru(CHRCH_(2)CH_(2)) (R = CH_3, CH_(2)CH_3, (CH_2)_)_(3)CH_3). EXSY NMR experiments at āˆ’87 Ā°C were used to determine the activation energies for both of these exchange processes. In addition, new methods have been developed for the direct preparation of metathesis-active ruthenacyclobutanes via the protonolysis of dichloro(1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene)(benzylidene) bis(pyridine)ruthenium(II) and its 3-bromopyridine analogue. Using either trifluoroacetic acid or silica-bound toluenesulfonic acid as the proton source, the ethylene-derived ruthenacyclobutane (H_(2)IMes)Cl_(2)Ru(CH_(2)CH_(2)CH_(2)) was observed in up to 98% yield via NMR at āˆ’40 Ā°C. On the basis of these studies, mechanisms accounting for the positional and stereochemical exchange within ruthenacyclobutanes are proposed, as well as the implications of these dynamics toward olefin metathesis catalyst and reaction design are described

    Abstractions for designing and evaluating communication bridges for people in developing regions

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    This paper describes two novel abstractions that help soft- ware engineers work in developing regions to align social and technical factors when building communication systems. The abstractions extend two concepts familiar to engineers of computer networks and applications: the Open Systems Interconnect stack for design, and Quality of Service for eval- uation. The novel nature of the abstractions lies in how they help cultivate awareness of socio-cultural and technical is- sues when designing and evaluating communication bridges in the eld. Advantages of the abstractions are that they can be understood easily by software engineers, they aid communication with bene ciaries, and can therefore facili- tate collaboration. The paper makes an argument for these socially aware abstractions, describes the abstractions in de- tail, provides examples of how we used the new abstractions in the eld and then gives practical guidelines for how to use them. The simple nature of the new abstractions can help software engineers and end-users to work together to produce useful information technology based communication systems for people in developing regions.Telkom, Cisco, THRIP, NRF, SANPADWeb of Scienc

    Using voice over IP to bridge the digital divide: a critical action research approach

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    There is a great disparity between those who have access to Information and Communication Technologies (ICTs) and those that do not. This phenomenon forms part of the Digital Divide. Many ICTs may be used to help overcome this divide if they are applied in a useful way, providing locally applicable content and services. Critical Action Research (CAR) is an approach used to develop such applications. CAR aims to empower people by involving them in the development process. Using CAR, this project investigates how Voice over IP (VoIP) may be applied in a productive way in an underserviced community. VoIP is an ICT used for sending voice over packet switched networks using Internet Protocol. It can be used to integrate data and voice to produce multimedia applications. In South Africa (SA), VoIP may only be provided by Telkom, the Second National Operator and the Under-Serviced Area Licensees. Using CAR and VoIP, an application is being developed to service a specific need of a particular rural community. The application will either provide a service to a small rural business or aid the provision of healthcare in rural areas. The project evaluates how well CAR integrates with a normal Software Development Lifecycle and makes policy recommendations for the use of VoIP in rural SA.Telkom, Siemens, THRI

    Telemedicine using VoIP combined with a store and forward approach

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    Rural areas in South Africa have unique conditions such as remoteness and scarcity of reliable public facilities. Information and Communication Technologies (ICTs) introduced into these areas must be suitable for these conditions. Using a user-centred design approach based on Participatory Design and Action Research, we have developed a telemedicine application for a rural village in the Eastern Cape. This paper describes how we determined the requirements and design for the application and why we chose Voice over Internet Protocol (VoIP) combined with a store and forward approach to achieve our telemedicine goals. We present an overview of the methodology we are using, describe the software application we have developed and mention several challenges we have faced to date. Finally we conclude that VoIP and store and forward technologies are appropriate to the South African rural situation.Telkom, Siemens, THRIP, IDRC, SANPADDepartment of HE and Training approved lis

    Multiepoch Radial Velocity Observations of L Dwarfs

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    We report on the development of a technique for precise radial-velocity measurements of cool stars and brown dwarfs in the near infrared. Our technique is analogous to the Iodine (I2) absorption cell method that has proven so successful in the optical regime. We rely on telluric CH4 absorption features to serve as a wavelength reference, relative to which we measure Doppler shifts of the CO and H2O features in the spectra of our targets. We apply this technique to high-resolution (R~50,000) spectra near 2.3 micron of nine L dwarfs taken with the Phoenix instrument on Gemini-South and demonstrate a typical precision of 300 m/s. We conduct simulations to estimate our expected precision and show our performance is currently limited by the signal-to-noise of our data. We present estimates of the rotational velocities and systemic velocities of our targets. With our current data, we are sensitive to companions with M sin i > 2MJ in orbits with periods less than three days. We identify no companions in our current data set. Future observations with improved signal-to-noise should result in radial-velocity precision of 100 m/s for L dwarfs.Comment: Accepted for publication in ApJ, 24 pages, 7 figure

    Seeing-limited Coupling of Starlight into Single-mode Fiber with a Small Telescope

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    An optical fiber link to a telescope provides many advantages for spectrometers designed to detect and characterize extrasolar planets through precise radial velocity (PRV) measurements. In the seeing-limited regime, a multi-mode fiber is typically used so that a significant amount of starlight may be captured. In the near-diffraction-limited case, either with an adaptive optics system or with a small telescope at an excellent site, efficiently coupling starlight into a much smaller, single-mode fiber may be possible. In general, a spectrometer designed for single-mode fiber input will be substantially less costly than one designed for multi-mode fiber input. We describe the results of tests coupling starlight from a 70 cm telescope at Mt. Hopkins, Arizona into the single-mode fiber of the MINERVA-Red spectrometer at a wavelength of ~850 nm using a low-speed tip/tilt image stabilization system comprising all commercial, off-the-shelf components. We find that approximately 0.5% of the available starlight is coupled into the single-mode fiber under seeing conditions typical for observatories hosting small telescopes, which is close to the theoretical expectation. We discuss scientific opportunities for small telescopes paired with inexpensive, high-resolution spectrometers, as well as upgrade paths that should significantly increase the coupling efficiency for the MINERVA-Red system.Comment: 8 pages, 4 figures. Accepted for publication in Astronomische Nachrichte
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