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- Pertl, Leonhard, et al.
(författare)
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Exports and Productivity : Comparable Evidence for 14 Countries
- 2007
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Ingår i: Policy Research Working Papers. - New York : World Bank. - 1813-9450.
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Rapport (refereegranskat)abstract
- The authors use comparable micro level panel data for 14 countries and a set of identically specified empirical models to investigate the relationship between exports and productivity. The overall results are in line with the big picture that is by now familiar from the literature: Exporters are more productive than non-exporters when observed and unobserved heterogeneity are controlled for, and these exporter productivity premia tend to increase with the share of exports in total sales; there is strong evidence in favour of self-selection of more productive firms into export markets, but nearly no evidence in favour of the learning-by-exporting hypothesis. The authors document that the exporter premia differ considerably across countries in identically specified empirical models. In a meta-analysis of their results the authors find that countries that are more open and have more effective government report higher productivity premia. However, the level of development per se does not appear to be an explanation for the observed cross-country differences.
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- Liapis, C. D., et al.
(författare)
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ESVS guidelines : Invasive treatment for carotid stenosis: indications, techniques
- 2009
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Ingår i: European Journal of Vascular and Endovascular Surgery. - : Elsevier BV. - 1078-5884 .- 1532-2165. ; 37:4, Suppl 1, s. S1-S19
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Tidskriftsartikel (refereegranskat)abstract
- The European Society for Vascular Surgery brought together a group of experts in the field of carotid artery disease to produce updated guidelines for the invasive treatment of carotid disease. The recommendations were rated according to the level of evidence. Carotid endarterectomy (CEA) is recommended in symptomatic patients with >50% stenosis if the perioperative stroke/death rate is <6% [A], preferably within 2 weeks of the patient's last symptoms [A]. CEA is also recommended in asymptomatic men <75 years old with 70-99% stenosis if the perioperative stroke/death risk is <3% [A]. The benefit from CEA in asymptomatic women is significantly less than in men [A]. CEA should therefore be considered only in younger, fit women [A]. Carotid patch angioplasty is preferable to primary closure [A]. Aspirin at a dose of 75-325 mg daily and statins should be given before, during and following CEA. [A] Carotid artery stenting (CAS) should be performed only in high-risk for CEA patients, in high-volume centres with documented low peri-operative stroke and death rates or inside a randomized controlled trial [C]. CAS should be performed under dual antiplatelet treatment with aspirin and clopidogrel [A]. Carotid protection devices are probably of benefit [C].
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- Maillefert, J. F., et al.
(författare)
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Multi-language translation and cross-cultural adaptation of the OARSI/OMERACT measure of intermittent and constant osteoarthritis pain (ICOAP)
- 2009
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Ingår i: Osteoarthritis and Cartilage. - : Elsevier BV. - 1063-4584. ; 17:10, s. 1293-1296
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Tidskriftsartikel (refereegranskat)abstract
- Aim: To conduct a multi-language translation and cross-cultural adaptation of the Intermittent and Constant OsteoArthritis Pain (ICOAP) questionnaire for hip and knee osteoarthritis (OA). Methods: The questionnaires were translated and cross-culturally adapted in parallel, using a common protocol, into the following languages: Czech, Dutch, French (France), German, Italian, Norwegian, Spanish (Castillan), North and Central American Spanish, Swedish. The process was conducted following five steps: (1) - independent translation into the target language by two or three persons; (2) - consensus meeting to obtain a single preliminary translated version; (3) - backward translation by an independent bilingual native English speaker, blinded to the English original version; (4) - final version produced by a multidisciplinary consensus committee; (5) - pre-testing of the final version with 10-20 target-language-native hip and knee OA patients. Results: The process could be followed and completed in all countries. Only slight differences were identified in the structure of the sentences between the original and the translated versions. A large majority of the patients felt that the questionnaire was easy to understand and complete. Only a few minor criticisms were expressed. Moreover, a majority of patients found the concepts of constant pain and pain that comes and goes to be of a great pertinence and were very happy with the distinction. Conclusion: The ICOAP questionnaire is now available for multi-center international studies. (c) 2009 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.
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- Antonelo, Eric Aislan, et al.
(författare)
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Intelligent autonomous navigation for mobile robots : Spatial concept acquisition and object discrimination
- 2005
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Ingår i: 2005 IEEE International Symposium on Computational Intelligence in Robotics and Automation, Proceedings. - New York : IEEE Press. - 0780393554 ; , s. 553-557
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Konferensbidrag (refereegranskat)abstract
- An autonomous system able to construct its own navigation strategy for mobile robots is proposed. The navigation strategy is molded from navigation experiences (succeeding as the robot navigates) according to a classical reinforcement learning procedure. The autonomous system is based on modular hierarchical neural networks. Initially the navigation performance is poor (many collisions occur). Computer simulations show that after a period of learning the autonomous system generates efficient obstacle avoidance and target seeking behaviors. Experiments also offer support for concluding that the autonomous system develops a variety of object discrimination capability and of spatial concepts.
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- Cunnea, P., et al.
(författare)
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Increased expression of specific thioredoxin family proteins; a pilot immunohistochemical study on human hepatocellular carcinoma
- 2007
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Ingår i: International journal of immunopathology and pharmacology. - : Biolife. - 0394-6320 .- 2058-7384. ; 20:1, s. 17-24
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Tidskriftsartikel (refereegranskat)abstract
- Hepatocellular Carcinoma (HCC) is one of the most frequent cancers worldwide, however, prognosis remains poor following its discovery. We investigate the Thioredoxin superfamily of proteins as diagnostic markers for HCC. Furthermore, we delineate possible roles of the endoplasmic reticulum member of the superfamily, ERdj5, in carcinogenesis. Using antibodies against Thioredoxin 1, Thioredoxin Reductase 1 and ERdj5, we performed immunohistochemistry on paraffin embedded liver biopsy sections from HCC patients. All three redox proteins exhibited elevated expression levels in tumor tissue compared to internal control, with ERdj5 showing a remarkable 3-fold increase. In vitro cell viability experiments using Hepatocellular Carcinoma HuH7 cells treated with ERdj5 small interfering RNA showed that ERdj5 knockdown cells exhibited less resistance to Doxorubicin (chemotherapy drug), but more resistance to Tunicamycin (Endoplasmic Stress inducer), compared to control cells. In conclusion, we introduce members of the Thioredoxin superfamily as possible immunohistochemical markers in the diagnostics of hepatocellular carcinoma and indicate a potential defensive role for ERdj5 in chemotherapeutic drug resistance.
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- Dourado, Daniel F A R, et al.
(författare)
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Glutathione transferase : new model for glutathione activation
- 2008
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Ingår i: Chemistry - A European Journal. - : Wiley. - 0947-6539 .- 1521-3765. ; 14:31, s. 9591-8
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Tidskriftsartikel (refereegranskat)abstract
- Glutathione transferases are enzymes of the cellular detoxification system that metabolize a vast spectrum of xenobiotic and endobiotic toxic compounds. They are homodimers or heterodimers and each monomer has an active center composed of a G-site in which glutathione (GSH) binds and an H-site for the electrophilic substrate. When GSH binds to the G-site, the pKa value of its thiol group drops by 2.5 units; this promotes its deprotonation and, therefore, produces a strong nucleophilic thiolate that is able to react with the electrophilic substrate. The mechanism behind the deprotonation of the thiol group is still unknown. Some studies point to the fact that the GSH glutamyl alpha-carboxylate group is essential for GSH activation, whereas others indicate the importance of the active-center water molecules. On the basis of QM/MM calculations, we propose a mechanism of GSH activation in which a water molecule, acting as a bridge, is able to assist in the transfer of the proton from the GSH thiol group to the GSH glutamyl alpha-carboxylate group, after an initial GSH conformational rearrangement. We calculated the potential of mean force of this GSH structural rearrangement that would be necessary for the approach of both groups and we then performed a QM/MM ONIOM scan of water-assisted proton transfer. The overall free-energy barrier for the process is consistent with experimental studies of the enzyme kinetics.
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- Felicissimo, Viviane, et al.
(författare)
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A theoretical study of the role of the hydrogen bond on core ionization of the water dimer
- 2005
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Ingår i: Chemical Physics. - : Elsevier. - 0301-0104 .- 1873-4421. ; 312:1-3, s. 311-318
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Tidskriftsartikel (refereegranskat)abstract
- Motivated by the interest in using X-ray spectra for probing of hydrogen bonded networks we developed a quantum model for simulations of the electronic-vibrational profile of the X-ray core photoelectron spectrum of the water dimer. It is found that the potential surfaces of the donor and acceptor O1s core-ionized states of this system display a qualitative difference. Large gradients of the potential in the core ionized state along some intermolecular coordinates combined with small vibrational frequencies breaks down completely the harmonic approximation. The band profiles are therefore treated using a quasi-continuum approximation. The weak hydrogen bonding and the drastic change of water dimer potential under core ionization is responsible for the anomalously strong vibrational broadening: 0.4 eV for the acceptor band and 0.6 eV for the donor band. The core ionization of the donor oxygen is accompanied by proton transfer which should be observable in X-ray fluorescence or Auger spectra.
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- Felicissimo, Viviane C., et al.
(författare)
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The principles of infrared-x-ray pump-probe spectroscopy. Applications on proton transfer in core-ionized water dimers
- 2005
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Ingår i: Journal of Chemical Physics. - : American Institute of Physics (AIP). - 0021-9606 .- 1089-7690. ; 122:9
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we derive the basic physics underlying infrared-x-ray pump-probe spectroscopy (IR, infrared). Particular features of the spectroscopy are highlighted and discussed, such as dependence on phase of the infrared pulse, duration and delay time of the x-ray pulse, and molecular orientation. Numerical applications are carried out for the water dimer using wave packet techniques. It is shown that core ionization of the donor oxygen of the water dimer results in a drastic change of the potential with the global minimum placed in the proton transfer region. The results of the modeling indicate that IR-x-ray pump-probe spectroscopy can be used to study the dynamics of proton transfer in this core-ionized state, and that, contrary to conventional core level photoelectron spectroscopy, x-ray core-ionization driven by an IR field is a proper method to explore the proton transfer in a system like the water dimer. We observe that the trajectory of the nuclear wave packet in the ground state potential well is strongly affected by the absolute phase of the IR pulse.
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- Guimaraes, Freddy Fernandes, et al.
(författare)
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Infrared–x-ray pump-probe spectroscopy of the NO molecule
- 2005
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 72:1
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Tidskriftsartikel (refereegranskat)abstract
- Two color infrared-x-ray pump-probe spectroscopy of the NO molecule is studied theoretically and numerically in order to obtain a deeper insight of the underlying physics and of the potential of this suggested technology. From the theoretical investigation a number of conclusions could be drawn: It is found that the phase of the infrared field strongly influences the trajectory of the nuclear wave packet, and hence, the x-ray spectrum. The trajectory experiences fast oscillations with the vibrational frequency with a modulation due to the anharmonicity of the potential. The dependences of the x-ray spectra on the delay time, the duration, and the shape of the pulses are studied in detail. It is shown that the x-ray spectrum keep memory about the infrared phase after the pump field left the system. This memory effect is sensitive to the time of switching-off the pump field and the Rabi frequency. The phase effect takes maximum value when the duration of the x-ray pulse is one-fourth of the infrared field period, and can be enhanced by a proper control of the duration and intensity of the pump pulse. The manifestation of the phase is different for oriented and disordered molecules and depends strongly on the intensity of the pump radiation.
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- Guimaraes, Freddy Fernandes, et al.
(författare)
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Phase sensitive x-ray absorption driven by strong infrared fields
- 2005
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 71:4
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Tidskriftsartikel (refereegranskat)abstract
- In this paper it is demonstrated that electron vibrational absorption of molecules driven by strong IR field provides rich physical interpretations of dynamical processes on a short time scale. The phase of an infrared field influences strongly the trajectory of the nuclear wave packet and the probing spectrum. It is shown that the probe spectrum keeps memory of the infrared phase even after that the pump field left the system. The phase effect takes maximum value when the duration of the probe pulse is of the order of the infrared field period, and can be enhanced by a proper control of the duration and intensity of the pump pulse. The phase effect is different for oriented and disordered molecules and depends strongly on the intensity of pump radiation. It can be an effective tool to study charge transfer processes like proton transfer in hydrogen bonded networks.
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- Guimaraes, Freddy Fernandes, et al.
(författare)
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Quantum wave packet revivals in IR plus X-ray pump-probe spectroscopy
- 2005
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Ingår i: Chemical Physics Letters. - : Elsevier. - 0009-2614 .- 1873-4448. ; 405:4-6, s. 398-403
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Tidskriftsartikel (refereegranskat)abstract
- The wave packet revivals constitute a central concept of X-ray spectroscopy with ultra-high spectral resolution. The revival phenomenon allows to resolve the anharmonical shift or rotational structure by means of time dependent measurements and makes X-ray pump-probe spectroscopy a powerful technique to study long-term dynamics of molecules in different phases. We study the revivals referring to the X-ray absorption spectrum of the NO molecule driven by strong infrared pulse. It is shown that the phase sensitive trajectories of the center of gravity of the wave packets and the X-ray spectra copy each other.
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