| 4981. |
- Yesuf, Mahmud, 1969
(författare)
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Risk, Time and Land Management under Market Imperfections: Applications to Ethiopia
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This Ph.D. thesis addresses both theoretical and empirical issues pertaining to land management decisions of farm households in developing countries working under an imperfect market and institutional setting (with case studies from Ethiopia). Using techniques in experimental economics, efforts are also made to assign some quantitative measures to the most important parameters (such as risk and time preferences) in the same decision making process. Paper I: A Dynamic Economic Model of Soil Conservation with Imperfect Markets and Institutions In this paper, we develop a dynamic soil conservation model that explicitly incorporates labor, capital and land market imperfections and their interactions to suit the problems of smallholders in many developing countries. We use the model to analyze the impact of these institutional and market imperfections on the optimal levels of labor allocations into cultivation and conservation efforts. Increased transaction cost in factor markets is found to have a direct impact on soil conservation effort by increasing its shadow prices and curtailing its demand. It also has an indirect impact on soil conservation by affecting the shadow price of the soil stock and hence enhancing or curtailing its demand depending on the initial factor endowments of farm households, the relative strength of conservation and cultivation inputs on the soil dynamics, the profit share of cultivation input, and the degree of interaction across the factor markets. The overall impact is thus inconclusive. Various possible scenarios are explored in the model. Paper II: Risk Preferences of Farm Households in Ethiopia This study measures farmersâ?? attitudes towards risk using an experimental approach for a sample of 262 farm households in the Ethiopian highlands. We find more than 50 percent of the households in the severe to extreme risk aversion category, with a constant partial risk aversion coefficient of more than 2.00. With careful construction of the experiment, the natures of absolute and partial risk aversion are examined, and our data supports the presence of Decreasing Absolute Risk Aversion (DARA) and Increasing Partial Risk Aversion (IPRA) behavior. The validity of some of the expected utility theory predictions is tested, and the predictions of risk neutrality for smaller stakes and predictions of similar preferences for gains and losses, which stem from the major tents of the theory (concavity and asset integration), are not supported by our experiment. Paper III: Time Preferences of Farm Households in Ethiopia This study measures
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| 4982. |
- Yilmaz, Aylin, 1974, et al.
(författare)
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Cerebrospinal fluid and plasma HIV-1 RNA levels and lopinavir concentrations following lopinavir/ritonavir regimen.
- 2004
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Ingår i: Scandinavian journal of infectious diseases. - : Informa UK Limited. - 0036-5548 .- 1651-1980. ; 36:11-12, s. 823-8
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Tidskriftsartikel (refereegranskat)abstract
- Our objective was to study the effect of lopinavir/ritonavir on cerebrospinal fluid (CSF) viral load as part of an antiretroviral combination treatment for HIV-1 infected individuals, and to determine the steady-state concentrations of lopinavir in CSF in relationship to plasma concentrations. Paired CSF and plasma samples from 12 antiretroviral-naïve HIV-1 infected patients starting combination therapy containing lopinavir/ritonavir were collected at baseline, and during treatment at a first follow-up at median 3.0 months (range 2.6-6.0 months), and at a second follow-up at median 12.1 months (range 6.0-16.5 months). Levels of HIV-1 RNA, CD4+ T-cell count, beta2-microglobulin, neopterin, and lopinavir concentration were analysed. In addition, CSF and plasma lopinavir concentrations in 4 patients already on combination therapy including lopinavir/ritonavir were analysed. Nine of 11 patients had undetectable viral load in CSF and 5/11 in plasma at the first follow-up. At the second follow-up 7/7 had undetectable viral load in CSF and 9/9 in plasma. Intrathecal immunoactivation, measured by neopterin and beta2-microglobulin, decreased significantly both in CSF and serum. The total CSF concentrations of lopinavir were of the same order of magnitude as the unbound concentrations in plasma. Lopinavir mean (+/-SD) concentrations were 42.1 (+/-31.5) nM in CSF and 52.7 (+/-25.2) nM unbound in plasma. We found that antiretroviral combination therapy including lopinavir/ritonavir substantially decreases the viral load, both in CSF and plasma, as well as the intrathecal immunoactivation, measured by beta2-microglobulin and neopterin. CSF concentrations of lopinavir were low, but probably sufficient to have a virological effect.
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| 4983. |
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| 4984. |
- Yoshihara, S., et al.
(författare)
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Long-lasting smooth-muscle relaxation by a novel PACAP analogue in human bronchi
- 2004
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Ingår i: Regul Pept. ; 123:1-3
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Tidskriftsartikel (refereegranskat)abstract
- We compared the relaxant effect of original pituitary adenylate cyclase-activating peptide (PACAP)1-27 with that of a newly developed, synthetic PACAP1-27 analogue, [Arg(15,20,21) Leu(17)]-PACAP-Gly-Lys-Arg-NH(2), in human bronchi in vitro (n=4-5 in each group). Using precontraction by carbachol (0.1 muM), cumulative administration of PACAP1-27 and salbutamol caused concentration-dependent smooth muscle relaxation with similar potencies and maximum relaxant effects. Non-cumulative administration of the PACAP1-27 analogue and the original PACAP1-27 caused concentration-dependent relaxation with a similar maximum relaxant effect and potency as well. However, the onset and offset of action was markedly slower for the PACAP1-27 analogue than for the original PACAP1-27 (>90% versus <10% of peak relaxation remaining 5 h after administration). Peptidase inhibition by captopril (10 muM) and phosphoramidon (1 muM) significantly increased the maximum relaxant effect and duration of action of PACAP1-27 but not of the PACAP1-27 analogue, during the 3 h of observation in the human bronchi. We conclude that [Arg(15,20,21) Leu(17)]-PACAP-Gly-Lys-Arg-NH(2) produces significant concentration-dependent and sustained bronchial smooth muscle relaxation in vitro. The sustained relaxant effect is due, at least in part, to the synthetic PACAP1-27 analogue being less susceptible to cleavage by peptidases than the original peptide PACAP1-27.
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| 4985. |
- Young, J. B., et al.
(författare)
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Mortality and morbidity reduction with Candesartan in patients with chronic heart failure and left ventricular systolic dysfunction: results of the CHARM low-left ventricular ejection fraction trials
- 2004
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Ingår i: Circulation. - 1524-4539. ; 110:17, s. 2618-26
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Patients with symptomatic chronic heart failure (CHF) and reduced left ventricular ejection fraction (LVEF) have a high risk of death and hospitalization for CHF deterioration despite therapies with angiotensin-converting enzyme (ACE) inhibitors, beta-blockers, and even an aldosterone antagonist. To determine whether the angiotensin-receptor blocker (ARB) candesartan decreases cardiovascular mortality, morbidity, and all-cause mortality in patients with CHF and depressed LVEF, a prespecified analysis of the combined Candesartan in Heart Failure Assessment of Reduction in Mortality and morbidity (CHARM) low LVEF trials was performed. CHARM is a randomized, double-blind, placebo-controlled, multicenter, international trial program. METHODS AND RESULTS: New York Heart Association (NYHA) class II through IV CHF patients with an LVEF of < or =40% were randomized to candesartan or placebo in 2 complementary parallel trials (CHARM-Alternative, for patients who cannot tolerate ACE inhibitors, and CHARM-Added, for patients who were receiving ACE inhibitors). Mortality and morbidity were determined in 4576 low LVEF patients (2289 candesartan and 2287 placebo), titrated as tolerated to a target dose of 32 mg once daily, and observed for 2 to 4 years (median, 40 months). The primary outcome (time to first event by intention to treat) was cardiovascular death or CHF hospitalization for each trial, with all-cause mortality a secondary end point in the pooled analysis of the low LVEF trials. Of the patients in the candesartan group, 817 (35.7%) experienced cardiovascular death or a CHF hospitalization as compared with 944 (41.3%) in the placebo group (HR 0.82; 95% CI 0.74 to 0.90; P<0.001) with reduced risk for both cardiovascular deaths (521 [22.8%] versus 599 [26.2%]; HR 0.84 [95% CI 0.75 to 0.95]; P=0.005) and CHF hospitalizations (516 [22.5%] versus 642 [28.1%]; HR 0.76 [95% CI 0.68 to 0.85]; P<0.001). It is important to note that all-cause mortality also was significantly reduced by candesartan (642 [28.0%] versus 708 [31.0%]; HR 0.88 [95% CI 0.79 to 0.98]; P=0.018). No significant heterogeneity for the beneficial effects of candesartan was found across prespecified and subsequently identified subgroups including treatment with ACE inhibitors, beta-blockers, an aldosterone antagonist, or their combinations. The study drug was discontinued because of adverse effects by 23.1% of patients in the candesartan group and 18.8% in the placebo group; the reasons included increased creatinine (7.1% versus 3.5%), hypotension (4.2% versus 2.1%), and hyperkalemia (2.8% versus 0.5%), respectively (all P<0.001). CONCLUSIONS: Candesartan significantly reduces all-cause mortality, cardiovascular death, and heart failure hospitalizations in patients with CHF and LVEF < or =40% when added to standard therapies including ACE inhibitors, beta-blockers, and an aldosterone antagonist. Routine monitoring of blood pressure, serum creatinine, and serum potassium is warranted.
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| 4986. |
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Young People, Soap Operas and Reality TV. Yearbook 2004
- 2004
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Samlingsverk (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- The transformation of the traditional soap opera into certain more extreme soaps, and the emergence of the recent ‘global’ reality TV formats have whipped up storms of controversy in a great number of countries. Such programmes have also generated worries among adults about how they are received by, and may influence, young viewers – because children from all over the world watch adult programming from an early age. Since research on young people and these fictional genres seriously lags behind, the primary aim of the Yearbook is to stimulate further research on the subject. In order to do so, the Clearinghouse invited scholars from all over the world to contribute their knowledge so far. Thus at the same time, the book gives answers to at least some of the questions on young people, soap operas and reality TV in the public debate.
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| 4987. |
- Yu, H.Y., et al.
(författare)
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Current enhancement with alternating gate voltage in the Coulomb blockade regime of a single wall carbon nanotube
- 2004
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Ingår i: Applied Physics A. - : Springer Science and Business Media LLC. - 0947-8396 .- 1432-0630. ; 79, s. 1613-1615
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the current–voltage characteristics of a carbon nanotube in a single electron transistor structure with alternating gate voltage. A continuous current enhancement effect with increasing frequency of the applied gate voltage up to 13 MHz is reported. Assuming that I=nef, more than 1000 electrons are driven to flow across the source–drain channel at VDS=100 mV, 13 MHz of gate voltage (Vp-p=2 V) and T=1.8 K. The continuous current enhancement is explained by the broadening effect of the discrete energy levels of the finite-length carbon nanotube.
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| 4988. |
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| 4989. |
- Zacharaki, E I, et al.
(författare)
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A digital subtraction radiography scheme based on automatic multiresolution registration.
- 2004
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Ingår i: Dento maxillo facial radiology. - : British Institute of Radiology. - 0250-832X. ; 33:6, s. 379-90
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To establish a digital subtraction radiography scheme for aligning clinical in vivo radiographs based on the implementations of an automatic geometric registration method and a contrast correction technique. METHODS: Thirty-five pairs of in vivo dental radiographs from four clinical studies were used in this work. First, each image pair was automatically aligned by applying a multiresolution registration strategy using the affine transformation followed by the implementation of the projective transformation at full resolution. Then, a contrast correction technique was applied in order to produce subtraction radiographs and fused images for further clinical evaluation. The performance of the proposed registration method was assessed against a manual method based on the projective transformation. RESULTS: The qualitative assessment of the experiments based on visual inspection has shown advantageous performance of the proposed automatic registration method against the manual method. Furthermore, the quantitative analysis showed statistical difference in terms of the root mean square (RMS) error estimated over the whole images and specific regions of interest. CONCLUSIONS: The proposed automatic geometric registration method is capable of aligning radiographs acquired with or without rigorous a priori standardization. The methodology is pixel-based and does not require the application of any segmentation process prior to alignment. The employed projective transformation provides a reliable model for registering intraoral radiographs. The implemented contrast correction technique sequentially applied provides subtraction radiographs and fused images for clinical evaluation regarding the evolution of a disease or the response to a therapeutic scheme.
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| 4990. |
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