| 1. |
- Abdo, A. A., et al.
(författare)
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A limit on the variation of the speed of light arising from quantum gravity effects
- 2009
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 462:7271, s. 331-334
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Tidskriftsartikel (refereegranskat)abstract
- A cornerstone of Einstein’s special relativity is Lorentz invariance—the postulate that all observers measure exactly the same speed of light in vacuum, independent of photon-energy. While special relativity assumes that there is no fundamental length-scale associated with such invariance, there is a fundamental scale (the Planck scale, lPlanck~1.62×10-33cm or EPlanck = MPlanckc2~1.22×1019GeV), at which quantum effects are expected to strongly affect the nature of space–time. There is great interest in the (not yet validated) idea that Lorentz invariance might break near the Planck scale. A key test of such violation of Lorentz invariance is a possible variation of photon speed with energy. Even a tiny variation in photon speed, when accumulated over cosmological light-travel times, may be revealed by observing sharp features in γ-ray burst (GRB) light-curves. Here we report the detection of emission up to ~31GeV from the distant and short GRB090510. We find no evidence for the violation of Lorentz invariance, and place a lower limit of 1.2EPlanck on the scale of a linear energy dependence (or an inverse wavelength dependence), subject to reasonable assumptions about the emission (equivalently we have an upper limit of lPlanck/1.2 on the length scale of the effect). Our results disfavour quantum-gravity theories in which the quantum nature of space–time on a very small scale linearly alters the speed of light.
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| 2. |
- Szatmari, Peter, et al.
(författare)
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Mapping autism risk loci using genetic linkage and chromosomal rearrangements.
- 2007
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 39:3, s. 319-328
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Tidskriftsartikel (refereegranskat)abstract
- Autism spectrum disorders (ASDs) are common, heritable neurodevelopmental conditions. The genetic architecture of ASDs is complex, requiring large samples to overcome heterogeneity. Here we broaden coverage and sample size relative to other studies of ASDs by using Affymetrix 10K SNP arrays and 1,168 families with at least two affected individuals, performing the largest linkage scan to date while also analyzing copy number variation in these families. Linkage and copy number variation analyses implicate chromosome 11p12-p13 and neurexins, respectively, among other candidate loci. Neurexins team with previously implicated neuroligins for glutamatergic synaptogenesis, highlighting glutamate-related genes as promising candidates for contributing to ASDs.
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| 3. |
- Herrero, M. Antonia, et al.
(författare)
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Synthesis and characterization of a carbon nanotube−dendron series for efficient sirna delivery
- 2009
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 131:28, s. 9843-9848
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Tidskriftsartikel (refereegranskat)abstract
- A new series of dendron-functionalized multiwalled carbon nanotube (MWNT) derivatives, characterized by the presence of numerous positively charged tetraalkyl ammonium salts at the periphery of the dendron, has been synthesized. The positive charges on the MWNT surface, coupled with the unique ability of carbon nanotubes (CNTs) to penetrate cell membranes, make the new derivatives potentially ideal vectors for siRNA delivery. Using a fluorescently labeled, noncoding siRNA sequence, we demonstrate that cytoplasmic delivery of the nucleic acid is remarkably increased throughout the different dendron generations. The work reported here highlights the fact that dendron-functionalized CNTs can be rationally designed as efficient carriers of siRNA that can eventually lead to gene silencing.
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| 4. |
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| 5. |
- Daşu, Alexandru, et al.
(författare)
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Theoretical simulation of tumour oxygenation--practical applications
- 2006
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Ingår i: Advances in Experimental Medicine and Biology. - : Springer US. - 0065-2598 .- 2214-8019. ; 578, s. 357-362
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Tidskriftsartikel (refereegranskat)abstract
- Theoretical simulation of tissue oxygenation is a robust method that can be used to quantify the tissue oxygenation for a variety of applications. However, it is necessary that the relevant input parameters are used for the model describing the tumour microenvironment. The results of the simulations presented in this article suggest that the accuracy of the simulations depends very much on the method of calculation of the effects of the temporal change of the hypoxic pattern due to the opening and the closure of blood vessels. Thus, the use of average oxygenations might lead to dangerous overestimations of the treatment response. This indicates that care should be taken when incorporating hypoxia information into the biological modelling of tumour response.
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| 6. |
- Gong, Xiaohong, et al.
(författare)
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Analysis of X chromosome inactivation in autism spectrum disorders.
- 2008
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Ingår i: American Journal of Medical Genetics. Part B, Neuropsychiatric Genetics. - : Wiley. - 1552-485X .- 1552-4841. ; 147B:6, s. 830-835
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Tidskriftsartikel (refereegranskat)abstract
- Autism spectrum disorders (ASD) are complex genetic disorders more frequently observed in males. Skewed X chromosome inactivation (XCI) is observed in heterozygous females carrying gene mutations involved in several X-linked syndromes. In this study, we aimed to estimate the role of X-linked genes in ASD susceptibility by ascertaining the XCI pattern in a sample of 543 informative mothers of children with ASD and in a sample of 163 affected girls. The XCI pattern was also determined in two control groups (144 adult females and 40 young females) with a similar age distribution to the mothers sample and affected girls sample, respectively. We observed no significant excess of skewed XCI in families with ASD. Interestingly, two mothers and one girl carrying known mutations in X-linked genes (NLGN3, ATRX, MECP2) showed highly skewed XCI, suggesting that ascertainment of XCI could reveal families with X-linked mutations. Linkage analysis was carried out in the subgroup of multiplex families with skewed XCI (> or = 80:20) and a modest increased allele sharing was obtained in the Xq27-Xq28 region, with a peak Z-score of 1.75 close to rs719489. In summary, our results suggest that there is no major X-linked gene subject to XCI and expressed in blood cells conferring susceptibility to ASD. However, the possibility that rare mutations in X-linked genes could contribute to ASD cannot be excluded. We propose that the XCI profile could be a useful criteria to prioritize families for mutation screening of X-linked candidate genes.
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| 7. |
- Toma-Dasu, Iuliana, et al.
(författare)
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Theoretical simulation of tumour hypoxia measurements
- 2006
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Ingår i: Advances in Experimental Medicine and Biology. - : Springer US. - 0065-2598 .- 2214-8019. ; 578, s. 369-374
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Tidskriftsartikel (refereegranskat)abstract
- Our simulations suggested that measurements performed in a limited number of points in the tumour can be representative for the situation in the whole tumour. It has further been shown that the polarographic electrode cannot be used to measure small regions of hypoxia. In fact it has been suggested that the most important factor that determines the efficiency of the polarographic electrode is the spatial distribution of the hypoxic cells and not their type, and therefore the polarographic electrode cannot be used to make the distinction between acute and chronic hypoxia. The simulations have also shown that it is reasonable to assume that the electrode measurement can be correlated to the situation in the whole tissue, even though the correlation is only qualitative. And because the electrode measurements are greatly influenced by the averaging process, the quantitative use of the electrode measurements may lead to erroneous results, especially for modelling the treatment response.
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