1,181 research outputs found

    Outward FDI from Southeast Asia: The Malaysian Experience

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    This paper analyses the trends, patterns and determinants of outward foreign direct investment (OFDI) by Malaysian companies. It shows that Malaysian OFDI ha d taken a quantum leap since 19 93 and the number of Malaysian TNCs investing abroad since the 1990s has increased significantly. The OFDI is focused mainly in services ( finance , banking, insurance and tourism) and natural resources (oil and gas) with manufacturing a distant third. This also includes the emergence of off shore financial centres and developed countries as the most important host region for trans - border activity although investment s in developing countries especially within ASEAN have shown tremendous growth. The key drivers of OFDI have been to increase efficiency, to access resources and to access markets

    Do vibrationally excited OH molecules affect middle and upper atmospheric chemistry?

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    Except for a few reactions involving electronically excited molecular or atomic oxygen or nitrogen, atmospheric chemistry modelling usually assumes that the temperature dependence of reaction rates is characterized by Arrhenius’ law involving kinetic temperatures. It is known, however, that in the upper atmosphere the vibrational temperatures may exceed the kinetic temperatures by several hundreds of Kelvins. This excess energy has an impact on the reaction rates. We have used upper atmospheric OH populations and reaction rate coefficients for OH(υ = 0...9)+O3 and OH(υ = 0...9)+O to estimate the effective (i.e. population weighted) reaction rates for various atmospheric conditions. We have found that the effective rate coefficient for OH(υ =0...9)+O3 can be larger by a factor of up to 1470 than that involving OH in its vibrational ground state only. At altitudes where vibrationally excited states of OH are highly populated, the OH reaction is a minor sink of Ox and O3 compared to other reactions involving, e.g., atomic oxygen. Thus the impact of vibrationally excited OH on the ozone or Ox sink remains small. Among quiescent atmospheres under investigation, the largest while still small (less than 0.1%) effect was found for the polar winter upper stratosphere and mesosphere. The contribution of the reaction of vibrationally excited OH with ozone to the OH sink is largest in the upper polar winter stratosphere (up to 4%), while its effect on the HO2 source is larger in the lower thermosphere (up to 1.5% for polar winter and 2.5% for midlatitude night conditions). For OH(υ =0...9)+O the effective rate coefficients are lower by up to 11% than those involving OH in its vibrational ground state. The effects on the odd oxygen sink are negative and can reach −3% (midlatitudinal nighttime lowermost thermosphere), i.e. neglecting vibrational excitation overestimates the odd oxygen sink. The OH sink is overestimated by up to 10%. After a solar proton event, when upper atmospheric OH can be enhanced by an order of magnitude, the excess relative odd oxygen sink by consideration of vibrational excitation in the reaction of OH(υ =0...9)+O3 is estimated at up to 0.2%, and the OH sink by OH(υ =0...9)+O can be reduced by 12% in the thermosphere by vibrational excitation

    Variability of NOx in the polar middle atmosphere from October 2003 to March 2004: vertical transport vs. local production by energetic particles

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    We use NO, NO2 and CO from MIPAS/ENVISAT to investigate the impact of energetic particle precipitation onto the NOx budget from the stratosphere to the lower mesosphere in the period from October 2003 to March 2004, a time of high solar and geomagnetic activity. We find that in the winter hemisphere the indirect effect of auroral electron precipitation due to downwelling of upper mesospheric/lower thermospheric air into the stratosphere prevails. Its effect exceeds even the direct impact of the very large solar proton event in October/November 2003 by nearly 1 order of magnitude. Correlations of NOx and CO show that the unprecedented high NOx values observed in the Northern Hemisphere lower mesosphere and upper stratosphere in late January and early February are fully consistent with transport from the upper mesosphere/lower thermosphere and subsequent mixing at lower altitudes. In the polar summer Southern Hemisphere, we observed an enhanced variability of NO and NO2 on days with enhanced geomagnetic activity, but this seems to indicate enhanced instrument noise rather than a direct increase due to electron precipitation. A direct effect of electron precipitation onto NOx can not be ruled out, but, if any, it is lower than 3 ppbv in the altitude range 40-56 km and lower than 6 ppbv in the altitude range 56-64 km. An additional significant source of NOx due to local production by precipitating electrons below 70 km exceeding several parts per billion as discussed in previous publications appears unlikely

    Invisible Z-Boson Decays at e+e- Colliders

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    The measurement of the invisible Z-boson decay width at e+e- colliders can be done "indirectly", by subtracting the Z-boson visible partial widths from the Z-boson total width, or "directly", from the process e+e- -> \gamma \nu \bar{\nu}. Both procedures are sensitive to different types of new physics and provide information about the couplings of the neutrinos to the Z-boson. At present, measurements at LEP and CHARM II are capable of constraining the left-handed Z\nu\nu-coupling, 0.45 <~ g_L <~ 0.5, while the right-handed one is only mildly bounded, |g_R| <= 0.2. We show that measurements at a future e+e- linear collider at different center-of-mass energies, \sqrt{s} = MZ and \sqrt{s}s ~ 170 GeV, would translate into a markedly more precise measurement of the Z\nu\nu-couplings. A statistically significant deviation from Standard Model predictions will point toward different new physics mechanisms, depending on whether the discrepancy appears in the direct or the indirect measurement of the invisible Z-width. We discuss some scenarios which illustrate the ability of different invisible Z-boson decay measurements to constrain new physics beyond the Standard Model

    Loss of the nucleoporin Aladin in central nervous system and fibroblasts of Allgrove Syndrome

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    Allgrove syndrome (AS) is a rare disease with broad neurological involvement. Neurodegeneration can affect spinal motor neurons, Purkinje cells, striatal neurons, and the autonomic system. The mechanisms that lead to neuronal loss are still unclear. Recessive mutations in the AAAS gene affect the encoded protein Aladin, which would normally localize to the cytoplasmic face of the nuclear membrane as part of the nuclear pore complex (NPC). While the NPC is known to be a key factor for nucleo-cytoplasmic transport, the precise role of Aladin has not been elucidated yet. Here, we explored the consequences of the homozygous AAAS mutation c.464G&gt;A (p.R155H) in central nervous system tissues and fibroblasts of a novel AS patient presenting motor neuron disease, cerebellar ataxia, and autonomic dysfunction. Neuropathological analyses showed severe loss of motor neurons and Purkinje cells, with significant reduction in the perinuclear expression of Aladin. A reduced amount of protein was detected in the nuclear membrane fraction of the patient's brain. RNA analysis revealed a significant reduction of the transcript AAAS-1, while the AAAS-2 transcript was upregulated in fibroblasts. To our knowledge, this is the first study to demonstrate the effects of AAAS mutations in human central nervous system

    Propagator of a Charged Particle with a Spin in Uniform Magnetic and Perpendicular Electric Fields

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    We construct an explicit solution of the Cauchy initial value problem for the time-dependent Schroedinger equation for a charged particle with a spin moving in a uniform magnetic field and a perpendicular electric field varying with time. The corresponding Green function (propagator) is given in terms of elementary functions and certain integrals of the fields with a characteristic function, which should be found as an analytic or numerical solution of the equation of motion for the classical oscillator with a time-dependent frequency. We discuss a particular solution of a related nonlinear Schroedinger equation and some special and limiting cases are outlined.Comment: 17 pages, no figure

    Bounds on the tau and muon neutrino vector and axial vector charge radius

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    A Majorana neutrino is characterized by just one flavor diagonal electromagnetic form factor: the anapole moment, that in the static limit corresponds to the axial vector charge radius . Experimental information on this quantity is scarce, especially in the case of the tau neutrino. We present a comprehensive analysis of the available data on the single photon production process e+e−−>ÎœÎœË‰Îłe^+ e^- -> \nu \bar\nu \gamma off Z-resonance, and we discuss the constraints that these measurements can set on for the tau neutrino. We also derive limits for the Dirac case, when the presence of a vector charge radius is allowed. Finally, we comment on additional experimental data on ΜΌ\nu_\mu scattering from the NuTeV, E734, CCFR and CHARM-II collaborations, and estimate the limits implied for and for the muon neutrino.Comment: 20 pages, 2 eps figures. CCFR data included in the analysis. Conclusion unchange

    Primordial Nucleosynthesis Constraints on Z' Properties

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    In models involving new TeV-scale Z' gauge bosons, the new U(1)' symmetry often prevents the generation of Majorana masses needed for a conventional neutrino seesaw, leading to three superweakly interacting ``right-handed'' neutrinos nu_R, the Dirac partners of the ordinary neutrinos. These can be produced prior to big bang nucleosynthesis by the Z' interactions, leading to a faster expansion rate and too much ^4He. We quantify the constraints on the Z' properties from nucleosynthesis for Z' couplings motivated by a class of E_6 models parametrized by an angle theta_E6. The rate for the annihilation of three approximately massless right-handed neutrinos into other particle pairs through the Z' channel is calculated. The decoupling temperature, which is higher than that of ordinary left-handed neutrinos due to the large Z' mass, is evaluated, and the equivalent number of new doublet neutrinos Delta N_nu is obtained numerically as a function of the Z' mass and couplings for a variety of assumptions concerning the Z-Z' mixing angle and the quark-hadron transition temperature T_c. Except near the values of theta_E6 for which the Z' decouples from the right-handed neutrinos, the Z' mass and mixing constraints from nucleosynthesis are much more stringent than the existing laboratory limits from searches for direct production or from precision electroweak data, and are comparable to the ranges that may ultimately be probed at proposed colliders. For the case T_c = 150 MeV with the theoretically favored range of Z-Z' mixings, Delta N_nu 4.3 TeV for any value of theta_E6. Larger mixing or larger T_c often lead to unacceptably large Delta N_nu except near the nu_R decoupling limit.Comment: 22 pages, 5 figures; two additional references adde
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