Shear waves induced by moving needle in MR Elastography

Magnetic Resonance Elastography (MRE) is a phase contrast-based method for observing shear wave propagation in a material to determine its stiffness. The objective of this study was to determine whether shear waves suitable for MRE can be induced using a moving acupuncture needle. Tissue-simulating bovine gel phantom and a 0.4mm diameter acupuncture needle were used in the experiment. The results showed that observable shear waves could be induced in the gel phantom by cyclic needle motion. The observed wavelength varied with excitation frequency, as expected. Generating shear waves using moving needles may be a useful tool to study the basic mechanism of acupuncture with MRE. Further study will be conducted to observe the wave motion in inhomogeneous media and acupuncture-induced effects in invivo studies.published_or_final_versio

The "Ram Effect": A "Non-Classical" Mechanism for Inducing LH Surges in Sheep

During spring sheep do not normally ovulate but exposure to a ram can induce ovulation. In some ewes an LH surge is induced immediately after exposure to a ram thus raising questions about the control of this precocious LH surge. Our first aim was to determine the plasma concentrations of oestradiol (E2) E2 in anoestrous ewes before and after the "ram effect" in ewes that had a "precocious" LH surge (starting within 6 hours), a "normal" surge (between 6 and 28h) and "late» surge (not detected by 56h). In another experiment we tested if a small increase in circulating E2 could induce an LH surge in anoestrus ewes. The concentration of E2 significantly was not different at the time of ram introduction among ewes with the three types of LH surge. "Precocious" LH surges were not preceded by a large increase in E2 unlike "normal" surges and small elevations of circulating E2 alone were unable to induce LH surges. These results show that the "precocious" LH surge was not the result of E2 positive feedback. Our second aim was to test if noradrenaline (NA) is involved in the LH response to the "ram effect". Using double labelling for Fos and tyrosine hydroxylase (TH) we showed that exposure of anoestrous ewes to a ram induced a higher density of cells positive for both in the A1 nucleus and the Locus Coeruleus complex compared to unstimulated controls. Finally, the administration by retrodialysis into the preoptic area, of NA increased the proportion of ewes with an LH response to ram odor whereas treatment with the α1 antagonist Prazosin decreased the LH pulse frequency and amplitude induced by a sexually active ram. Collectively these results suggest that in anoestrous ewes NA is involved in ram-induced LH secretion as observed in other induced ovulators

Cataract surgery in uveitis: a multicentre database study

BACKGROUND/AIMS: Cataract is an important source of visual loss in patients with uveitis. Whether or not outcomes of cataract surgery in eyes with uveitis are worse compared with non-uveitic eyes have to date been compromised by lack of reliable estimates of benefit and harm, which require data from large cohorts. METHODS: Electronic medical record data were extracted from eight independent UK clinical sites for eyes undergoing cataract extraction between January 2010 and December 2014. 1173 eyes with a recorded diagnosis of uveitis were compared with a reference group of 95 573 eyes from the same dataset. RESULTS: Uveitic eyes represented 1.2% of all eyes undergoing cataract surgery. Eyes in the uveitic group had worse preoperative visual acuity (0.87 vs 0.65 logarithm of the minimum angle of resolution (logMAR) units), were from younger patients and had shorter axial lengths and a higher incidence of ocular copathology including glaucoma. A greater number had documented small pupils, required additional surgical procedures, developed more intraoperative complications and had poorer postoperative visual acuity at all time points measured up to 6 months (0.41 vs 0.27 logMAR units at 12-24 weeks). CONCLUSIONS: This large study cohort of eyes with a diagnosis of uveitis undergoing cataract surgery highlights more precisely the complex surgical demands, copathology and worse visual outcomes in this group. These data will allow more accurate preoperative counselling and planning. Although improvement in visual acuity is achieved in most cases, prognosis should be guarded, so that patient expectations are met. Compared with the non-uveitic population, the mean postoperative visual acuity is between one and two lines worse at all time points

Importance of dose-schedule of 5-aza-2'-deoxycytidine for epigenetic therapy of cancer

<p>Abstract</p> <p>Background</p> <p>The inactivation of tumor suppressor genes (TSGs) by aberrant DNA methylation plays an important role in the development of malignancy. Since this epigenetic change is reversible, it is a potential target for chemotherapeutic intervention using an inhibitor of DNA methylation, such as 5-aza-2'-deoxycytidine (DAC). Although clinical studies show that DAC has activity against hematological malignancies, the optimal dose-schedule of this epigenetic agent still needs to be established.</p> <p>Methods</p> <p>Clonogenic assays were performed on leukemic and tumor cell lines to evaluate the <it>in vitro </it>antineoplastic activity of DAC. The reactivation of TSGs and inhibition of DNA methylation by DAC were investigated by reverse transcriptase-PCR and Line-1 assays. The <it>in vivo </it>antineoplastic activity of DAC administered as an i.v. infusion was evaluated in mice with murine L1210 leukemia by measurement of survival time, and in mice bearing murine EMT6 mammary tumor by excision of tumor after chemotherapy for an <it>in vitro </it>clonogenic assay.</p> <p>Results</p> <p>Increasing the DAC concentration and duration of exposure produced a greater loss of clonogenicity for both human leukemic and tumor cell lines. The reactivation of the TSGs (<it>p57KIP2 </it>in HL-60 leukemic cells and <it>p16CDKN2A </it>in Calu-6 lung carcinoma cells) and the inhibition of global DNA methylation in HL-60 leukemic cells increased with DAC concentration. In mice with L1210 leukemia and in mice bearing EMT6 tumors, the antineoplastic action of DAC also increased with the dose. The plasma level of DAC that produced a very potent antineoplastic effect in mice with leukemia or solid tumors was > 200 ng/ml (> 1 μM).</p> <p>Conclusion</p> <p>We have shown that intensification of the DAC dose markedly increased its antineoplastic activity in mouse models of cancer. Our data also show that there is a good correlation between the concentrations of DAC that reduce <it>in vitro </it>clonogenicity, reactivate TSGs and inhibit DNA methylation. These results suggest that the antineoplastic action of DAC is related to its epigenetic action. Our observations provide a strong rationale to perform clinical trials using dose intensification of DAC to maximize the chemotherapeutic potential of this epigenetic agent in patients with cancer.</p

Observation of the Fractional Quantum Hall Effect in Graphene

When electrons are confined in two dimensions and subjected to strong magnetic fields, the Coulomb interactions between them become dominant and can lead to novel states of matter such as fractional quantum Hall liquids. In these liquids electrons linked to magnetic flux quanta form complex composite quasipartices, which are manifested in the quantization of the Hall conductivity as rational fractions of the conductance quantum. The recent experimental discovery of an anomalous integer quantum Hall effect in graphene has opened up a new avenue in the study of correlated 2D electronic systems, in which the interacting electron wavefunctions are those of massless chiral fermions. However, due to the prevailing disorder, graphene has thus far exhibited only weak signatures of correlated electron phenomena, despite concerted experimental efforts and intense theoretical interest. Here, we report the observation of the fractional quantum Hall effect in ultraclean suspended graphene, supporting the existence of strongly correlated electron states in the presence of a magnetic field. In addition, at low carrier density graphene becomes an insulator with an energy gap tunable by magnetic field. These newly discovered quantum states offer the opportunity to study a new state of matter of strongly correlated Dirac fermions in the presence of large magnetic fields

Effect of temperature anisotropy on various modes and instabilities for a magnetized non-relativistic bi-Maxwellian plasma

Using kinetic theory for homogeneous collisionless magnetized plasmas, we present an extended review of the plasma waves and instabilities and discuss the anisotropic response of generalized relativistic dielectric tensor and Onsager symmetry properties for arbitrary distribution functions. In general, we observe that for such plasmas only those electromagnetic modes whose magnetic field perturbations are perpendicular to the ambient magneticeld, i.e.,B1 \perp B0, are effected by the anisotropy. However, in oblique propagation all modes do show such anisotropic effects. Considering the non-relativistic bi-Maxwellian distribution and studying the relevant components of the general dielectric tensor under appropriate conditions, we derive the dispersion relations for various modes and instabilities. We show that only the electromagnetic R- and L- waves, those derived from them and the O-mode are affected by thermal anisotropies, since they satisfy the required condition B1\perpB0. By contrast, the perpendicularly propagating X-mode and the modes derived from it (the pure transverse X-mode and Bernstein mode) show no such effect. In general, we note that the thermal anisotropy modifies the parallel propagating modes via the parallel acoustic effect, while it modifies the perpendicular propagating modes via the Larmor-radius effect. In oblique propagation for kinetic Alfven waves, the thermal anisotropy affects the kinetic regime more than it affects the inertial regime. The generalized fast mode exhibits two distinct acoustic effects, one in the direction parallel to the ambient magnetic field and the other in the direction perpendicular to it. In the fast-mode instability, the magneto-sonic wave causes suppression of the firehose instability. We discuss all these propagation characteristics and present graphic illustrations

Phylogeographic analysis and genetic structure of an endemic sino-japanese disjunctive genus Diabelia (caprifoliaceae)

The Sino-Japanese Floristic Region (SJFR) is a key area for plant phylogeographical research, due to its very high species diversity and disjunct distributions of a large number of species and genera. At present, the root cause and temporal origin of the discontinuous distribution of many plants in the Sino-Japanese flora are still unclear. Diabelia (Caprifoliaceae; Linnaeoideae) is a genus endemic to Asia, mostly in Japan, but two recent discoveries in China raised questions over the role of the East China Sea (ECS) in these species' disjunctions. Chloroplast DNA sequence data were generated from 402 population samples for two regions (rpl32-trnL, and trnH-psbA) and 11 nuclear microsatellite loci were screened for 549 individuals. Haplotype, population-level structure, combined analyses of ecological niche modeling, and reconstruction of ancestral state in phylogenies were also performed. During the Last Glacial Maximum (LGM) period after the Tertiary, Diabelia was potentially widely distributed in southeastern China, the continental shelf of the East China Sea and Japan (excluding Hokkaido). After LGM, all populations in China have disappeared except those in Zhejiang which may represent a Glacial refuge. Populations of Diabelia in Japan have not experienced significant bottleneck effects, and populations have maintained a relatively stable state. The observed discontinuous distribution of Diabelia species between China and Japan are interpreted as the result of relatively ancient divergence. The phylogenetic tree of chloroplast fragments shows the characteristics of multi-origin evolution (except for D. sanguinea). STRUCTURE analysis of nuclear Simple Sequence Repeat (nSSR) showed that the plants of the Diabelia were divided into five gene pools: D. serrata, D. spathulata, D. sanguinea, D. ionostachya (D. spathulata var. spathulata-Korea), and populations of D. ionostachya var. ionostachya in Yamagata prefecture, northern Japan. Molecular evidence provides new insights of Diabelia into biogeography, a potential glacial refuge, and population-level genetic structure within species. In the process of species differentiation, ECS acts as a corridor for two-way migration of animals and plants between China and Japan during glacial maxima, providing the possibility of secondary contact for discontinuously distributed species between China and Japan, or as a filter (creating isolation) during glacial minima. The influence of the ECS in speciation and biogeography of Diabelia in the Tertiary remains unresolved in this study. Understanding origins, evolutionary histories, and speciation will provide a framework for the conservation and cultivation of Diabelia

Towards the Formalization of Fractional Calculus in Higher-Order Logic

Fractional calculus is a generalization of classical theories of integration and differentiation to arbitrary order (i.e., real or complex numbers). In the last two decades, this new mathematical modeling approach has been widely used to analyze a wide class of physical systems in various fields of science and engineering. In this paper, we describe an ongoing project which aims at formalizing the basic theories of fractional calculus in the HOL Light theorem prover. Mainly, we present the motivation and application of such formalization efforts, a roadmap to achieve our goals, current status of the project and future milestones.Comment: 9 page