1,117 research outputs found
An Empirical Growth Model for Major Oil Exporters
This paper develops a long-run growth model for a major oil exporting economy and derives conditions under which oil revenues are likely to have a lasting impact. This approach contrasts with the standard literature on the "Dutch disease" and the "resource curse", which primarily focuses on short-run implications of a temporary resource discovery. Under certain regularity conditions and assuming a Cobb-Douglas production function, it is shown that (log) oil exports enter the long-run output equation with a coefficient equal to the share of capital (). The long-run theory is tested using quarterly data on nine major oil economies, six of which are current members of OPEC (Iran, Kuwait, Libya, Nigeria, Saudi Arabia, and Venezuela), plus Indonesia which is a former member, and Mexico and Norway, which are members of the OECD. Overall, the test results support the long-run theory. The existence of long-run relations between real output, foreign output and real oil income is established for six of the nine economies considered. The exceptions, Mexico and Norway, do not possess sufficient oil reserves for oil income to have lasting impacts on their economies. At their current production rates, the proven oil reserves of Mexico and Norway are expected to last 9 and 10 years respectively, as compared to reserve-production ratios of OPEC members, which lie in the range of 45 to 125 years. For Indonesia, whose share of oil income in GDP has been declining steadily over the past three decades, the theory suggests that the effect of oil income on the economy's steady state growth rate will vanish eventually, and this is indeed confirmed by the results. Sensible estimates of a are also obtained across the six economies with long-run output equations, and impulse responses are provided for the effects of shocks to oil income and foreign output in these economies
Control of Dynamic Systems via Neural Networks
This report is devoted to the problem of controlling a class of linear time-invariant dynamic systems via controllers based on additive neural network models. In particular, the tracking and stabilization problems are considered. First, we show how to transform the problem of tracking a reference signal by a control system into the stabilization problem. Then, some concepts from the variable structure control theory are utilized to construct stabilizing controllers. In order to facilitate the stability analysis of the closed-loop systems we employ a special state space transformation. This transformation allows us also to reveal connections between the proposed controllers and the additive neural network models
Spin Fidelity for Three-qubit Greenberger-Horne-Zeilinger and W States Under Lorentz Transformations
Constructing the reduced density matrix for a system of three massive
spin particles described by a wave packet with Gaussian momentum
distribution and a spin part in the form of GHZ or W state, the fidelity for
the spin part of the system is investigated from the viewpoint of moving
observers in the jargon of special relativity. Using a numerical approach, it
turns out that by increasing the boost speed, the spin fidelity decreases and
reaches to a non-zero asymptotic value that depends on the momentum
distribution and the amount of momentum entanglement.Comment: 12pages, 2 figure
Dynamics of the intratumoral immune response during progression of high-grade serous ovarian cancer
PURPOSE: Tumor-infiltrating lymphocytes (TILs) have an established impact on the prognosis of high-grade serous ovarian carcinoma (HGSOC), however, their role in recurrent ovarian cancer is largely unknown. We therefore systematically investigated TIL densities and MHC class I and II (MHC1, 2) expression in the progression of HGSOC. EXPERIMENTAL DESIGN: CD3+, CD4+, CD8+ TILs and MHC1, 2 expression were evaluated by immunohistochemistry on tissue microarrays in 113 paired primary and recurrent HGSOC. TILs were quantified by image analysis. All patients had been included to the EU-funded OCTIPS FP7 project. RESULTS: CD3+, CD4+, CD8+ TILs and MHC1 and MHC2 expression showed significant correlations between primary and recurrent tumor levels (Spearman rho 0.427, 0.533, 0.361, 0.456, 0.526 respectively; P<.0001 each). Paired testing revealed higher CD4+ densities and MHC1 expression in recurrent tumors (Wilcoxon P=.034 and P=.018). There was also a shift towards higher CD3+ TILs levels in recurrent carcinomas when analyzing platinum-sensitive tumors only (Wilcoxon P=.026) and in pairs with recurrent tumor tissue from first relapse only (Wilcoxon P=.031). High MHC2 expression was the only parameter to be significantly linked to prolonged progression-free survival after first relapse (PFS2, log-rank P=.012). CONCLUSIONS: This is the first study that analyzed the development of TILs density and MHC expression in paired primary and recurrent HGSOC. The level of the antitumoral immune response in recurrent tumors was clearly dependent on the one in the primary tumor. Our data contribute to the understanding of temporal heterogeneity of HGSOC immune microenvironment and have implications for selection of samples for biomarker testing in the setting of immune-targeting therapeutics
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Genotype Directed Therapy in Murine Mismatch Repair Deficient Tumors
The PI3K/AKT/mTOR pathway has frequently been found activated in human tumors. We show that in addition to Wnt signaling dysfunction, the PI3K/AKT/mTOR pathway is often upregulated in mouse Msh2−/− initiated intestinal tumors. NVP-BEZ235 is a dual PI3K/mTOR inhibitor toxic to many cancer cell lines and currently involved in clinical trials. We have treated two mouse models involving Msh2 that develop small intestinal and/or colonic tumors with NVP-BEZ235, and a subset of animals with NVP-BEZ235 and MEK inhibitor ADZ4266. The disease phenotype has been followed with pathology, 18F FDG PET imaging, and endoscopy. Intestinal adenocarcinomas are significantly decreased in multiplicity by both drug regimens. The majority of tumors treated with combined therapy regress significantly, while a small number of highly progressed tumors persist. We have examined PTEN, AKT, MEK 1&2, MAPK, S6K, mTOR, PDPK1, and Cyclin D1 and find variable alterations that include downregulation of PTEN, upregulation of AKT and changes in its phosphorylated forms, upregulation of pMEK 1&2, p42p44MAPK, pS6K, and Cyclin D1. Apoptosis has been found intact in some tumors and not in others. Our data indicate that NVP-BEZ235 alone and in combination with ADZ4266 are effective in treating a proportion of colorectal cancers, but that highly progressed resistant tumors grow in the presence of the drugs. Pathways upregulated in some resistant tumors also include PDPK1, suggesting that metabolic inhibitors may also be useful in treating these tumors
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