A Late Eocene- Oligocene through-flowing river between the Upper Yangtze and South China Sea

We test the hypothesis of a major Paleogene river draining the SE Tibetan Plateau and the central modern Yangtze Basin that then flowed South to the South China Sea. We test this model using U Pb dated detrital zircon grains preserved in Paleogene sedimentary rocks in northern Vietnam and SW China. We applied a series of statistical tests to compare the U-Pb age spectra of the rocks in order to highlight differences and similarities between them and with potential source bedrocks. Monte Carlo mixing models imply that erosion was dominantly derived from the Indochina and Songpan-Garzê Blocks and to a lesser extent the Yangtze Craton. Some of the zircon populations indicate local erosion and sedimentation, but others show close similarity both within northern Vietnam, as well as more widely in the Eocene Jianchuan, Paleocene-Oligocene Simao and Oligocene-Miocene Yuanjiang basins of China. The presence of younger (<200 Ma) zircons from the Qamdo Block of Tibet are less easily explicable in terms of recycling by erosion of older sedimentary rocks and imply a regional drainage linking SE Tibet and the South China Sea in the Late Eocene-Oligocene. Detrital zircons from offshore in the South China Sea showed initial local erosion, but with a connection to a river stretching to SE Tibet in the Late Oligocene. A change from regional to local sources in the Early Miocene in the Yuanjiang Basin indicates the timing of disruption of the old drainage driven by regional plateau uplift

Physical aspects of treatment planning in linac-based radiosurgery of intracranial lesions

A review of physical aspects of treatment planning in stereotactic radiosurgery is presented.A target localization procedure, a dose calculation algorithm in a linac-based stereotactic radiosurgery and multi-isocentre planning for large lesions are described and discussed

E2F Activation of S Phase Promoters via Association with HCF-1 and the MLL Family of Histone H3K4 Methyltransferases

E2F transcriptional regulators control human-cell proliferation by repressing and activating the transcription of genes required for cell-cycle progression, particularly the S phase. E2F proteins repress transcription in association with retinoblastoma pocket proteins, but less is known about how they activate transcription. Here, we show that the human G1 phase regulator HCF-1 associates with both activator (E2F1 and E2F3a) and repressor (E2F4) E2F proteins, properties that are conserved in insect cells. Human HCF-1-E2F interactions are versatile: their associations and binding to E2F-responsive promoters are cell-cycle selective, and HCF-1 displays coactivator properties when bound to the E2F1 activator and corepressor properties when bound to the E2F4 repressor. During the G1-to-S phase transition, HCF-1 recruits the mixed-lineage leukemia (MLL) and Set-1 histone H3 lysine 4 methyltransferases to E2F-responsive promoters and induces histone methylation and transcriptional activation. These results suggest that HCF-1 induces cell-cycle-specific transcriptional activation by E2F proteins to promote cell proliferation

Low genetic diversity in Polish populations of sibling ant species: Lasius niger (L.) and Lasius platythorax Seifert (Hymenoptera, Formicidae)

We present preliminary data on mitochondrial DNA diversity within and among populations of the ants Lasius niger and Lasius platythorax in Poland. Phylogenetic analysis based on the mitochondrial DNA markers: cytochrome c oxidase subunit I (cox1) and 16S ribosomal RNA (16S rRNA) confirms the species status of L. niger and L. platythorax. Intraspecific variability is low in both species, which might be a result of severe bottlenecks and rapid postglacial expansion into Central Europe

Maximum human objectively measured pharmacologically stimulated accommodative amplitude

Purpose: To measure the maximum, objectively measured, accommodative amplitude, produced by pharmacologic stimulation. Methods: Thirty-seven healthy subjects were enrolled, with a mean age of 20.2±1.1 years, corrected visual acuity of 20/20, and mean spherical equivalent refraction (SER) =–0.83±1.60 diopters. For each subject, the right pupil was dilated with phenylephrine 10%. After 30 minutes, the pupil was measured, the left eye was patched, and the right eye was autorefracted. Pilocarpine 4% was then instilled in the right eye, followed by phenylephrine. At 45 minutes after the pilocarpine, autorefraction and pupil size were again measured. Results: Mean pupil size pre- and postpilocarpine was 8.0±0.8 mm and 4.4±1.9 mm, respectively. Pre- and postpilocarpine, the mean SER was –0.83±1.60 and –10.55±4.26 diopters, respectively. The mean pilocarpine-induced accommodative amplitude was 9.73±3.64 diopters. Five subjects had accommodative amplitudes ≥14.00 diopters. Accommodative amplitude was not significantly related to baseline SER (p-value =0.24), pre- or postpilocarpine pupil size (p-values =0.13 and 0.74), or change in pupil size (p-value =0.37). Iris color did not statistically significantly affect accommodative amplitude (p-value =0.83). Conclusion: Following topically applied pilocarpine, the induced objectively measured accommodation in the young eye is greater than or equal to the reported subjectively measured voluntary maximum accommodative amplitude

57. Physical and dosimetric aspects of quality assurance in stereotactic radiotherapy

A quality assurance system in stereotactic radiosurgery and stereotactic fractionated radiotherapy, concerning the physical and dosimetric aspects, may be divided into three elements: (1) the preparation of reliable basic data for the computerized treatment planning system; (2) a control of the accelerator parameters prior to patient treatment; (3) preparation of the optimal treatment plan with the treatment planning system.Due to the small size of the beams formed by circular collimators (7.5–35 mm diameter, BrainLab System) the smallest available detectors should be used for measurements – a diamond diode (0.3 mm thickness) and a 0.015 cm3 ionization chamber (PTW Freiburg) are adequate to measure precisely TMR curves, beam profiles and output factors required for the treatment planning system BrainScan.The full control of accelerator parameters (Clinac 2300 C/D) necessary to safely carry out the treatment requires a comprehensive list of tests (an extended list of weekly checks including Winston-Lutz test). Testing procedure carried out with a set of specialized devices (Med-Tec, Radak, BrainLab) takes about two hours. Proper accelerator check and regulations allow for very precise patient positioning.Treatment planning (with the treatment planning system BrainScan) is based on a series of CT and MR scans with target volume and organs at risk marked on each slice by the radiotherapist. The planner has to select the positions of isocentres (up to 3), collimator diameters, number and range of the arcs. Additional parameters for optimization procedure are the total dose proportions delivered by each arc. The treatment plan evaluation is based on the analysis of DVHs for target volume and also for organs at risk (orbits, optical nerves, brain stem) in order to minimize the dose and volume irradiated. It was accepted that the dose uniformity factor, defined as a ratio Dmin/Dmax within the target volume, should be not less than 0.8, and should approach 0.9 as much as possible.The above-presented system of quality control, specifying tolerance limits of controlled parameters, assures safe and precise dose delivery in stereotactic radiotherapy