| 1. |
- Schael, S, et al.
(författare)
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Precision electroweak measurements on the Z resonance
- 2006
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Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
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Forskningsöversikt (refereegranskat)abstract
- We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLID experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, m(Z) and Gamma(Z), and its couplings to fermions, for example the p parameter and the effective electroweak mixing angle for leptons, are precisely measured: m(Z) = 91.1875 +/- 0.0021 GeV, Gamma(Z) = 2.4952 +/- 0.0023 GeV, rho(l) = 1.0050 +/- 0.0010, sin(2)theta(eff)(lept) = 0.23153 +/- 0.00016. The number of light neutrino species is determined to be 2.9840 +/- 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m(t) = 173(+10)(+13) GeV, and the mass of the W boson, m(W) = 80.363 +/- 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of m(t) and m(W), the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level. (c) 2006 Elsevier B.V. All rights reserved.
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| 2. |
- Bromée, Torun, et al.
(författare)
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Uneven Evolutionary Rates of Bradykinin B1 and B2 Receptors in Vertebrate Lineages
- 2006
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Ingår i: Gene. - : Elsevier. - 0378-1119 .- 1879-0038. ; 373, s. 100-108
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Tidskriftsartikel (refereegranskat)abstract
- Bradykinin acts through two receptor subtypes in mammals and generates a variety of responses including pain, inflammation and hypotension. The evolutionary history of the bradykinin system has been unclear due to shortage of information outside mammals. We describe here two receptor subtypes and the bradykinin precursor in three species of bony fish (the zebrafish Danio rerio, the Japanese pufferfish Takifugu rubripes, and the green spotted pufferfish Tetraodon nigroviridis) and chicken and analyze the relationships to mammals by a combination of phylogeny, conserved synteny and exon–intron organization. All of these species have two receptor genes located close to each other in a tandem formation, with the B2 gene 5′ to the B1 gene, in chromosomal regions displaying conserved synteny between the species (albeit conservation of synteny in zebrafish is still unclear due to poor genome assembly). The evolutionary rate differs between the two genes as well as between lineages leading to differing pharmacological properties for both B1 and B2 across vertebrate classes. Also the bradykinin precursor gene was identified in all of these species in a chromosome region with conserved synteny. The tissue distribution of mRNA in T. rubripes is similar for B1 and B2, suggesting more similar regulation for the two genes than in mammals. In conclusion, the receptor tandem duplication predates the divergence of ray-finned fish and tetrapods and no additional duplicates of the receptors or bradykinin seem to have survived the ray-finned fish tetraploidization.
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| 3. |
- Fang, Qiu, et al.
(författare)
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Photodissociation of phosgene : Theoretical evidence for the ultrafast and synchronous concerted three-body process
- 2009
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 131:16
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Tidskriftsartikel (refereegranskat)abstract
- The potential energy surfaces for Cl2CO dissociation into CO+Cl+Cl in the lowest two electronic singlet states (S-0 and S-1) have been determined by the complete active space self-consistent field, coupled-cluster method with single and double excitations (CCSD), and equation-of-motion CCSD calculations, which are followed by direct ab initio molecular dynamics simulations to explore its photodissociation dynamics at 230 nm. It is found that the C-O stretching mode is initially excited upon irradiation and the excess internal energies are transferred to the C-Cl symmetric stretching mode within 200 fs. On average, the first and the second C-Cl bonds break completely within subsequent 60 and 100 fs, respectively. Electronic structure and dynamics calculations have thus provided a strong evidence that the photoinitiated dissociation of Cl2CO at 230 nm or shorter wavelengths is an ultrafast, adiabatic, and concerted three-body process. Since the two C-Cl bonds begin to break at the same time and the time interval between the two C-Cl bond broken fully is very short (similar to 40 fs), the photoinitiated dissociation of Cl2CO to CO+2Cl can be considered as the synchronous concerted process.
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| 4. |
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| 5. |
- Hu, Minyu, et al.
(författare)
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Comparison of lycopene and fluvastatin effects on atherosclerosis induced by a high-fat diet in rabbits
- 2008
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Ingår i: Nutrition Journal. - : Elsevier BV. - 1475-2891 .- 1475-2891. ; 24:10, s. 1030-1038
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Tidskriftsartikel (refereegranskat)abstract
- Objective We evaluated the antiatherogenic effect of lycopene in rabbits fed a high-fat diet. Methods Forty adult male rabbits were divided into five groups that were fed a standard diet, a high-fat diet, a high-fat diet plus 4 mg/kg of lycopene, a high-fat diet plus 12 mg/kg of lycopene, and a high-fat diet plus 10 mg/kg of fluvastatin, respectively. Lycopene and fluvastatin were administered intragastrically. The level of serum total cholesterol, total triglyceride, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, total antioxidant capacity, and malondialdehyde were measured before and after 4 and 8 wk of experimental treatment. In addition, plasma levels of lycopene, oxidized low-density lipoprotein, serum nitric oxide, and interleukin-1 were measured after the experiment. The area of atherosclerotic plaque and pathologic changes of the aorta were evaluated. Results Compared with the control, levels of total cholesterol, total triacylglycerol, low-density lipoprotein cholesterol, malonaldehyde, oxidized low-density lipoprotein, and interleukin-1 were increased and total antioxidant capacity and nitric oxide were decreased in the animals with a high-fat diet (P < 0.05). Intragastric administration of lycopene counteracted the change in these parameters (P < 0.05). In this case, the data showed that lycopene in the used dose was better than the fluvastatin intervention. Morphologic analysis revealed that lycopene and fluvastatin markedly reduced the formation of atherosclerotic plaques in the aorta compared with the situation in rabbits on a high-fat diet alone. Conclusion Lycopene, like fluvastatin, significantly attenuated atherogenesis in rabbits fed a high-fat diet.
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| 6. |
- Klionsky, Daniel J., et al.
(författare)
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Guidelines for the use and interpretation of assays for monitoring autophagy in higher eukaryotes
- 2008
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Ingår i: Autophagy. - : Landes Bioscience. - 1554-8627 .- 1554-8635. ; 4:2, s. 151-175
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Forskningsöversikt (refereegranskat)abstract
- Research in autophagy continues to accelerate,1 and as a result many new scientists are entering the field. Accordingly, it is important to establish a standard set of criteria for monitoring macroautophagy in different organisms. Recent reviews have described the range of assays that have been used for this purpose.2,3 There are many useful and convenient methods that can be used to monitor macroautophagy in yeast, but relatively few in other model systems, and there is much confusion regarding acceptable methods to measure macroautophagy in higher eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers of autophagosomes versus those that measure flux through the autophagy pathway; thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from fully functional autophagy that includes delivery to, and degradation within, lysosomes (in most higher eukaryotes) or the vacuole (in plants and fungi). Here, we present a set of guidelines for the selection and interpretation of the methods that can be used by investigators who are attempting to examine macroautophagy and related processes, as well as by reviewers who need to provide realistic and reasonable critiques of papers that investigate these processes. This set of guidelines is not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to verify an autophagic response.
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| 7. |
- Lagerström, Malin C., et al.
(författare)
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Origin of the prolactin-releasing hormone (PRLH) receptors : Evidence of coevolution between PRLH and a redundant neuropeptide Y receptor during vertebrate evolution
- 2005
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Ingår i: Genomics. - : Elsevier BV. - 0888-7543 .- 1089-8646. ; 85:6, s. 688-703
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Tidskriftsartikel (refereegranskat)abstract
- We present seven new vertebrate homologs of the prolactin-releasing hormone receptor (PRLHR) and show that these are found as two separate subtypes, PRLHR1 and PRLHR2. Analysis of a number of vertebrate sequences using phylogeny, pharmacology, and paralogon analysis indicates that the PRLHRs are likely to share a common ancestry with the neuropeptide Y (NPY) receptors. Moreover, a micromolar level of NPY was able to bind and inhibit completely the PRLH-evoked response in PRLHR1-expressing cells. We suggest that an ancestral PRLH peptide started coevolving with a redundant NPY binding receptor, which then became PRLHR, approximately 500 million years ago. The PRLHR1 subtype was shown to have a relatively high evolutionary rate compared to receptors with fixed peptide preference, which could indicate a drastic change in binding preference, thus supporting this hypothesis. This report suggests how gene duplication events can lead to novel peptide ligand/receptor interactions and hence spur the evolution of new physiological functions.
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| 8. |
- Lin, Cindy Shin-Yi, et al.
(författare)
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Axonal changes in spinal cord injured patients distal to the site of injury.
- 2007
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Ingår i: Brain : a journal of neurology. - : Oxford University Press (OUP). - 1460-2156. ; 130:Pt 4, s. 985-94
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Tidskriftsartikel (refereegranskat)abstract
- It is generally assumed that the peripheral nervous system remains intact following a spinal injury. Accordingly, the electrical thresholds of motor axons in a peripheral nerve below the lesion should be similar to those in intact subjects. Yet in attempts to enter the common peroneal nerve with microelectrodes in 24 quadriplegic or paraplegic individuals it was often found that electrical stimulation over or within the nerve failed to elicit contractions in the pre-tibial flexors. To investigate whether consistent changes in axonal physiology occurred distal to the site of injury in patients with spinal cord injury (SCI), motor nerve excitability was formally tested in 15 of these patients. Threshold tracking techniques were used to measure axonal excitability parameters (stimulus-response curves, strength-duration properties, threshold electrotonus, a current-threshold relationship and the recovery cycle) of motor axons in the median and common peroneal nerves. In these patients motor axons were uniformly of high threshold and consequently, stimulus-response curves were shifted to the right. In some SCI patients, axons were completely inexcitable. Amplitudes of compound motor action potentials were reduced, consistent with axonal loss and strength-duration time constant was significantly reduced in SCI patients (SCI 0.13 +/- 0.02 ms, controls 0.43 +/- 0.02 ms, mean +/- SE, P < 0.0001). Excitability changes were more prominent the more clinically severe the injury, with progressive deterioration over time since the original injury. While compression and traction sustained during the original injury or subsequent hospital rehabilitation may contribute in part to some of these changes, it is difficult to attribute these findings solely to such processes. Changes in axonal structure and ion channel function, but perhaps more critically decentralization and consequent inactivity, are likely to underlie the complex changes observed in axonal excitability in SCI patients.
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| 9. |
- Lin, Li-Li, et al.
(författare)
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Effect of Aromatic Coupling on Electronic Transport in Bimolecular Junctions
- 2009
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 113:32, s. 14474-14477
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Tidskriftsartikel (refereegranskat)abstract
- We have performed a systematic first-principles study on conductance-voltage characteristics of bioligo(phenylene ethynylene)-monothiol molecular junctions as recently reported by Wu et al.[Nalure Nanotech. 2008, 3, 569]. It is found that the molecular conductance is very sensitive to the vertical distance between two molecules as well as the titled angle between two molecular planes. By comparing with experimental results, key structure parameters for bimolecular junction are determined, indicating that in the experimental devices, the vertical distance between two molecules is around 0.30 mn, the two planar molecules have a cofacial arrangement, and the length of the molecular bridge is about 2.88 nm. The underlying mechanism for electron transport in these aromatically coupled bimolecular junctions has also been discussed.
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| 10. |
- Lin, Na, et al.
(författare)
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Solvent Effects on the Three-Photon Absorption of a Symmetric Charge-Transfer Molecule
- 2008
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 112, s. 4703-4710
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Tidskriftsartikel (refereegranskat)abstract
- We present a theoretical study of the solvent-induced three-photon absorption cross section of a highly conjugated fluorene derivative, performed using density functional (DFT) cubic response theory in combination with the polarizable continuum model. The applicability of the often used two-state model is examined by comparison against the full DFT response theory results. It is found that the simplified model performs poorly for the three-photon absorption properties of our symmetric charge-transfer molecule. The dielectric medium enhances the three-photon absorption cross section remarkably. The effects of solvent polarity and geometrical distortions have been carefully examined. A detailed comparison with experiment is presented.
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