1,642 research outputs found
The Development of Global Science.
How do we build research capacity throughout the world and capture the great human potential? To us, the answer is rather straightforward: the time-honored tradition of scientific mentoring must be practiced on a wider scale across borders. Herein, we detail the necessity for expanding mentorship to a global scale and provide several important principles to be considered when designing, planning, and implementing programs and centers of research around the world
The incidence of graft on developing-country firms
This paper measures the extent to which firms in developing countries are the target of bribes. Using new firm-level survey data from 33 African and Latin American countries, we first show that perceptions adjust slowly tofirms'experience with corrupt officials and hence are an imperfect proxy for the true incidence of graft. We then construct an experience-based index that reflects the probability that a firm will be asked for a bribe in order to complete a specified set of business transactions. On average, African firms are three times as likely to be asked for bribes as are firms in Latin America, although there is substantial variation within each region. Last, we show that graft appears to be more prevalent in countries with excessive regulation and where democracy is weak. In particular, our results suggest that the incidence of graft in Africa would fall by approximately 85 percent if countries in the region had levels of democracy and regulation similar to those that exist in Latin America.Public Sector Corruption&Anticorruption Measures,Corruption&Anitcorruption Law,Crime and Society,E-Business,Access to Finance
Troubleshooting Time-Dependent Density-Functional Theory for Photochemical Applications: Oxirane
The development of analytic-gradient methodology for excited states within
conventional time-dependent density-functional theory (TDDFT) would seem to
offer a relatively inexpensive alternative to better established
quantum-chemical approaches for the modeling of photochemical reactions.
However, even though TDDFT is formally exact, practical calculations involve
the use of approximate functionals, in particular the TDDFT adiabatic
approximation, whose use in photochemical applications must be further
validated. Here, we investigate the prototypical case of the symmetric CC ring
opening of oxirane. We demonstrate by direct comparison with the results of
high-quality quantum Monte Carlo calculations that, far from being an
approximation on TDDFT, the Tamm-Dancoff approximation (TDA) is a practical
necessity for avoiding triplet instabilities and singlet near instabilities,
thus helping maintain energetically reasonable excited-state potential energy
surfaces during bond breaking. Other difficulties one would encounter in
modeling oxirane photodynamics are pointed out but none of these is likely to
prevent a qualitatively correct TDDFT/TDA description of photochemistry in this
prototypical molecule.Comment: 19 pages, 17 figures, submitted to the Journal of Chemical Physic
Perancangan Sistem Pengendalian Suhu Kumbung Jamur Dengan Logika Fuzzy
Penelitian ini difokuskan pada pengendalian suhu kumbung jamur tiram dengan kontrol fuzzy gain scheduling yang digunakan untuk mentuning Kp, Ki, dan Kd agar diperoleh respon yang terbaik untuk aktuator sprayer dan blower. Pemodelan matematis ARX untuk membuat fungsi pengendalian suhu terhadap kelembaban. Variabel input yang digunakan dalam kontrol logika fuzzy GS ini adalah nilai setpoint suhu dan error suhu. Hasil output dari kontrol logika fuzzy adalah nilai otomatis tuning dari Kp, Ki, Kd Dari hasil fitting data real plant dengan data estimasi dengan menggunakan pemodelan ARX, diperoleh angka 66, 69% dan 54,49% untuk hasil fitting data real plant dengan data validasi. Dilihat dari bentuk kurva yang diperoleh, terdapat kesamaan tren antara data real plant dengan data estimasi maupun validasi. Telah dilakukan uji open loop dan juga close pada sistem pengendalian yang dirancang. Pemberian nilai set point pada suhu yang sesuai untuk pertumbuhan jamur yaitu pada suhu 28° C dapat dicapai dan dipertahankan dengan nilai maximum overshoot dari pengendali tersebut sebesar 0.89% dan time settling sekitar 325 detik. Fungsi suhu terhadap kelembaban dengan pemodelan ARX menghasilkan respon sistem dengan maximum overshoot dari pengendali tersebut sebesar 35% dan time settling sekitar 240 detik, dan error steady state sebesar 0,03%
Metal Organic Frameworks as Emerging Photocatalysts
Increasing number of metal-organic frameworks (MOFs) have recently been recognised as a new generation of emerging porous photocatalysts in photocatalysis and photoelectrocatalysis, since their intrinsic coordination structure between the metal cluster and organic ligands offers MOFs great flexibility to tune their semiconducting property for enhanced light harvesting. In order to improve their performance substantially and achieve widespread application of MOF photocatalysts, it is necessary to develop effective synthesis strategies and understand their semiconducting crystal structure, photocatalytic mechanism in depth. This chapter firstly provides a brief introduction of the MOF materials; this chapter addresses the crystallinity, porosity and electronic semiconducting structures that are essential in solar energy conversion. Established and innovative syntheses strategies of MOFs are then categorised and illustrated, followed by various characterisations techniques applied to investigate their structural and semiconducting properties (band structure and charge transfer), including X-ray Diffraction XRD, small angle X-ray Diffraction SAXRD, adsorption/desorption, UV-Vis, nuclear magnetic resonance (NMR), extended fine Auger structures (EXFAS), inelastic neutron scattering (INS) spectroscopy, high-resolution transmission electron microscopy (HR)TEM and electrochemical measurements. The photocatalytic and photoelectrocatalytic application of MOFs are introduced addressing their unique photocatalytic mechanism. The perspectives of MOF photocatalysts are finally presented to encourage the future development. The content of this chapter suits the users including beginners, postgraduates and professionals
First XMM-Newton observations of strongly magnetic cataclysmic variables - II. Timing studies of DP Leo and WW Hor
XMM-Newton was used to observe two eclipsing, magnetic cataclysmic variables,
DP Leo and WW Hor, continuously for three orbital cycles each. Both systems
were in an intermediate state of accretion. For WW Hor we also obtained optical
light curves with the XMM-Newton Optical Monitor and from ground-based
observations. Our analysis of the X-ray and optical light curves allows us to
constrain physical and geometrical parameters of the accretion regions and
derive orbital parameters and eclipse ephemerides of the systems. For WW Hor we
directly measure horizontal and vertical temperature variations in the
accretion column. From comparisons with previous observations we find that
changes in the accretion spot longitude are correlated with the accretion rate.
For DP Leo the shape of the hard X-ray light curve is not as expected for
optically thin emission, showing the importance of optical depth effects in the
post-shock region. We find that the spin period of the white dwarf is slightly
shorter than the orbital period and that the orbital period is decreasing
faster than expected for energy loss by gravitational radiation alone.Comment: Accepted for publication in MNRAS, 12 pages, 6 figure
Plaza de la Memoria Localidad de San Javier
50 p.El proyecto de tĂtulo nace de la reflexiĂłn sobre los limites urbano-rurales de la ciudad y como estos se han ido convirtiendo muchas veces en basurales de la ciudad. La inquietud por el estudio de estos limites de ciudad fue el punto de partida de la bĂşsquedad en esta problemática, ese interĂ©s apuntĂł a poner atenciĂłn en la localidad de San Javier y en su problemática, de cĂłmo llegaba a su limite con la rivera colindante de el Loncomilla. En la cual, era evidente su condiciĂłn de lĂmite ya que dividia ambos mundos tanto el rĂo como la ciudad. La propuesta plantea la apariciĂłn de un borde entre ciudad y rĂo (urbano-rural) un concepto más amable que conecte ambas situaciones. El "hacia una arquitectura de la integraciĂłn de las partes" fue la mirada aplicada, una vez en el lugar, sumar elementos propios de lugar, que se fueron convirtiendo en los elementos de proyectaciĂłn: una historia muy rica que encerraba dicho lugar, una escalera hecha por los vecinos para bajar al rĂo, una defensa para las crecidas del rĂo, las ruinas del antiguo puente loncomilla, paisaje, topografĂa. Con una idea de ser puestos en valor como un total
- …