Accretion Discs with an Inner Spiral Density Wave

In Montgomery (2009a), we show that accretion discs in binary systems could retrogradely precess by tidal torques like the Moon and the Sun on a tilted, spinning, non-spherical Earth. In addition, we show that the state of matter and the geometrical shape of the celestial object could significantly affect the precessional value. For example, a Cataclysmic Variable (CV) Dwarf Novae (DN) non-magnetic system that shows negative superhumps in its light curve can be described by a retrogradely precessing, differentially rotating, tilted disc. Because the disc is a fluid and because the gas stream overflows the tilted disc and particles can migrate into inner disc annuli, coupled to the disc could be a retrogradely precessing inner ring that is located near the innermost annuli of the disc. However, numerical simulations by Bisikalo et al. (2003, 2004) and this work show that an inner spiral density wave can be generated instead of an inner ring. Therefore, we show that retrograde precession in non-magnetic, spinning, tilted CV DN systems can equally be described by a retrogradely precessing and differentially rotating disc with an attached retrogradely precessing inner spiral density wave so long as the wave appears at the same radius as the ring and within the plane of the tilted disc. We find that the theoretical results generated in this work agree well with the theoretical results presented in Montgomery (2009a) and thus with the numerical simulations and select CV DN systems in Montgomery (2009b) that may have a main sequence secondary. Therefore, pressure effects do need to be considered in CV DN systems that exhibit negative superhumps if the accretion discs are tilted and have an inner spiral density wave that is in the plane of the disc

TSC22 in mammary gland development and breast cancer

Mammary gland involution is characterised by a high degree of apoptosis. By identifying genes that are upregulated at this developmental stage, we aimed to discover key factors that are involved in the induction of mammary epithelial cell death and therefore present potential tumour suppressors for breast cancer. Among 96 genes recently identified as specifically upregulated early during involution were the transforming growth factor beta (TGFβ)-stimulated clone 22 homologue (TSC-22/TGFβ1-induced transcript 4) and TGFβ3 [1]. TGFβ3 has recently been shown to be necessary for induction of apoptosis during mammary gland involution, while TSC-22 overexpression can lead to cell death. We have therefore tested whether TSC-22 mRNA expression can be induced by TGFβ3 and whether it is involved in or necessary for TGFβ-induced apoptosis. We further show that TSC-22 can enhance TGFβ3-induced Smad response and epithelial cell death. In addition, overexpression of TSC-22 alone can induce a Smad response and apoptosis in mammary epithelial cell cultures, which is independent of p53. Further, we have performed tests to study the necessity for Smad proteins during TSC-22-induced apoptosis, and to establish the intracellular localisation of TSC-22. A pilot study on a small cohort of archival breast cancer cases, representing all stages of malignant progression, shows that TSC-22 protein was reduced or undetectable in 60% of breast carcinomas when compared with adjacent normal breast tissue, suggesting that TSC-22 could indeed be a potential novel tumour suppressor gene. We shall present data showing that methylation of the TSC-22 promoter is not involved in the reduction of TSC-22 protein in breast cancer

SPH Simulations of Negative (Nodal) Superhumps: A Parametric Study

Negative superhumps in cataclysmic variable systems result when the accretion disc is tilted with respect to the orbital plane. The line of nodes of the tilted disc precesses slowly in the retrograde direction, resulting in a photometric signal with a period slightly less than the orbital period. We use the method of smoothed particle hydrodynamics to simulate a series of models of differing mass ratio and effective viscosity to determine the retrograde precession period and superhump period deficit $\varepsilon_-$ as a function of system mass ratio $q$. We tabulate our results and present fits to both $\varepsilon_-$ and $\varepsilon_+$ versus $q$, as well as compare the numerical results with those compiled from the literature of negative superhump observations. One surprising is that while we find negative superhumps most clearly in simulations with an accretion stream present, we also find evidence for negative superhumps in simulations in which we shut off the mass transfer stream completely, indicating that the origin of the photometric signal is more complicated than previously believed.Comment: 14 pages, 15 figures. Accepted for publication in MNRA

Nova V5116 Sgr and searching for superhumps in nova remnants

We present the period analysis of unfiltered photometric observations of V5116 Sgr (Nova Sgr 2005 #2) and we search for superhump candidates in novae remnants. The PDM method for period analysis is used. The masses of the novae componets are estimated from the secondary mass -- orbital period and primary mass -- decline time relations. We found that 13 nights of V5116 Sgr observations in the year 2006 are modulated with a period of $0.1238 \pm 0.0001$ d ($2.9712 \pm 0.0024$ h). Following the shape of the phased light curves and no apparent change in the value of the periodicity in different subsamples of the data, we interpret the period as orbital in nature. The binary system then falls within the period gap of the orbital period distribution of cataclysmic variables. From the maximum magnitude -- rate of decline relation, we estimate the maximum absolute visual magnitude of $M_{\rm Vmax} = -8.85 \pm 0.04$ mag using the measured value of decline $t_{\rm 2} = 6.5 \pm 1.0$ d. The mass-period relation for cataclysmic variables yields a secondary mass estimate of about $0.26 \pm 0.05 {\rm M}_{\rm \odot}$. We propose that V5116 Sgr is a high inclination system showing an irradiation effect of the secondary star. No fully developed accretion disc up to the tidal radius with the value lower than $3.5 10^{10}$ cm is probable. The mass ratio was estimated in a few novae and the presence or absence of superhumps in these systems was compared with the mass ratio limit for superhumps of about 0.35. We found that in the majority of novae with expected superhumps, this variability has not been found yet. Therefore, more observations of these systems is encouraged.Comment: 9 pages, 7 figures, accepted for publication in A&

Cross sectional study of performance indicators for English Primary Care Trusts: testing construct validity and identifying explanatory variables

BACKGROUND: The performance of Primary Care Trusts in England is assessed and published using a number of different performance indicators. Our study has two broad purposes. Firstly, to find out whether pairs of indicators that purport to measure similar aspects of quality are correlated (as would be expected if they are both valid measures of the same construct). Secondly, we wanted to find out whether broad (global) indicators correlated with any particular features of Primary Care Trusts, such as expenditure per capita. METHODS: Cross sectional quantitative analysis using data from six 2004/05 PCT performance indicators for 303 English Primary Care Trusts from four sources in the public domain: Star Rating, aggregated Quality and Outcomes Framework scores, Dr Foster mortality index, Dr Foster equity index (heart by-pass and hip replacements), NHS Litigation Authority Risk Management standards and Patient Satisfaction scores from the Star Ratings. Forward stepwise multiple regression analysis to determine the effect of Primary Care Trust characteristics on performance. RESULTS: Star Rating and Quality and Outcomes Framework total, both summary measures of global quality, were not correlated with each other (F = 0.66, p = 0.57). There were however positive correlations between Quality and Outcomes Framework total and patient satisfaction (r = 0.61, p < 0.001) and between screening/'additional services' indicators on the Star Ratings and Quality and Outcomes Framework (F = 24, p < 0.001). There was no correlation between different measures of access to services. Likewise we found no relationship between either Star Rating or Litigation Authority Standards and hospital mortality (F = 0.61, p = 0.61; F = 0.31, p = 0.73). CONCLUSION: Performance assessment in healthcare remains on the Government's agenda, with new core and developmental standards set to replace the Star Ratings in 2006. Yet the results of this analysis provide little evidence that the current indicators have sufficient construct validity to measure the underlying concept of quality, except when the specific area of screening is considered

Sonic Hedgehog Signaling Promotes Peri-Lesion Cell Proliferation and Functional Improvement after Cortical Contusion Injury

Traumatic brain injury (TBI) is a leading cause of death and disability globally. No drug treatments are available, so interest has turned to endogenous neural stem cells (NSCs) as alternative strategies for treatment. We hypothesized that regulation of cell proliferation through modulation of the sonic hedgehog pathway, a key NSC regulatory pathway, could lead to functional improvement. We assessed sonic hedgehog (Shh) protein levels in the cerebrospinal fluid (CSF) of patients with TBI. Using the cortical contusion injury (CCI) model in rodents, we used pharmacological modulators of Shh signaling to assess cell proliferation within the injured cortex using the marker 5-Ethynyl-2’-deoxyuridine (EdU); 50mg/mL. The phenotype of proliferating cells was determined and quantified. Motor function was assessed using the rotarod test. In patients with TBI there is a reduction of Shh protein in CSF compared with control patients. In rodents, following a severe CCI, quiescent cells become activated. Pharmacologically modulating the Shh signaling pathway leads to changes in the number of newly proliferating injury-induced cells. Upregulation of Shh signaling with Smoothened agonist (SAG) results in an increase of newly proliferating cells expressing glial fibrillary acidic protein (GFAP), whereas the Shh signaling inhibitor cyclopamine leads to a reduction. Some cells expressed doublecortin (DCX) but did not mature into neurons. The SAG-induced increase in proliferation is associated with improved recovery of motor function. Localized restoration of Shh in the injured rodent brain, via increased Shh signaling, has the potential to sustain endogenous cell proliferation and the mitigation of TBI-induced motor deficits albeit without the neuronal differentiation

On the Change of the Inner Boundary of an Optically Thick Accretion Disk around White Dwarfs Using the Dwarf Nova SS Cyg as an Example

We present the results of our studies of the aperiodic optical flux variability for SS Cyg, an accreting binary systemwith a white dwarf. The main set of observational data presented here was obtained with the ANDOR/iXon DU-888 photometer mounted on the RTT-150 telescope, which allowed a record(for CCD photometers) time resolution up to 8 ms to be achieved. The power spectra of the source's flux variability have revealed that the aperiodic variability contains information about the inner boundary of the optically thick flow in the binary system. We show that the inner boundary of the optically thick accretion disk comes close to the white dwarf surface at the maximum of the source's bolometric light curve, i.e., at the peak of the instantaneous accretion rate onto the white dwarf, while the optically thick accretion disk is truncated at distances 8.5e9 cm ~10 R_{WD} in the low state. We suggest that the location of the inner boundary of the accretion disk in the binary can be traced by studying the parameters of the power spectra for accreting white dwarfs. In particular, this allows the mass of the accreting object to be estimated.Comment: 9 pages, 7 figures, Published in Astronomy Letter

Atlas of Tilted Accretion Disks & Source to Negative Superhumps

Using smoothed particle hydrodynamics, we numerically simulate steady state accretion discs for Cataclysmic Variable Dwarf Novae systems that have a secondary-to-primary mass ratio (0.35 \le q \le 0.55). After these accretion discs have come to quasi-equilibrium, we rotate each disc out of the orbital plane by (\delta = (1, 2, 3, 4, 5,) or (20)^{o}) to induce negative superhumps. For accretion discs tilted $5^{o}$, we generate light curves and associated Fourier transforms for an atlas on negative superhumps and retrograde precession. Our simulation results suggest that accretion discs need to be tilted more than three degrees for negative superhumps to be statistically significant. We also show that if the disc is tilted enough such that the gas stream strikes a disc face, then a dense cooling ring is generated near the radius of impact. In addition to the atlas, we study these artificially tilted accretion discs to find the source to negative superhumps. Our results suggest that the source is additional light from innermost disc annuli, and this additional light waxes and wanes with the amount of gas stream overflow received as the secondary orbits. The nodes, where the gas stream transitions from flowing over to under the disc rim (and vice versa), precess in the retrograde direction.Comment: 10 pages, 14 figures in Journal: Royal Astronomical Society and Blackwell Publishing. The definitive version is available at http://www.blackwellsynergy.com or at http://www3.interscience.wiley.com/journal/122269928/abstrac

A case report of bilateral synovial chondromatosis of the ankle

<p>Abstract</p> <p>Background</p> <p>Synovial chondromatosis is a rare, generally benign condition which affects synovial membranes. It most commonly involves large joints such as the knee, hip, and elbow, but its presence in smaller joints has also been reported. The diagnosis of synovial chondromatosis is commonly made following a thorough history, physical examination, and radiographic examination. Patients may report pain and swelling within a joint which is often aggravated with physical activity.</p> <p>Case presentation</p> <p>A rare case of bilateral synovial chondromatosis of the ankle is reviewed. A 26 year-old male presented with chronic bilateral ankle pain. Physical examination suggested and imaging confirmed multiple synovial chondromatoses bilaterally, likely secondary to previous trauma.</p> <p>Conclusion</p> <p>The clinical and imaging findings, along with potential differential diagnoses, are described. Since this condition tends to be progressive but self-limiting, indications for surgery depend on the level of symptomatic presentation in addition to the functional demands of the patient. Following a surgical consultation, it was decided that it was not appropriate to pursue surgery at the present time.</p

Cyclical period changes in the dwarf novae V2051 Oph and V4140 Sgr

We report the identification of cyclical changes in the orbital period of the eclipsing dwarf novae V2051 Ophiuchi and V4140 Sagitarii. We used sets of white dwarf mid-eclipse timings to construct observed-minus-calculated diagrams covering, respectively, 25 and 16 years of observations. The V2051 Oph data present cyclical variations that can be fitted by a linear plus sinusoidal function with period 22 +/- 2 yr and amplitude 17 +/- 3 s. The statistical significance of this period by an F-test is larger than 99.9 per cent. The V4140 Sgr data present cyclical variations of similar amplitude and period 6.9 +/- 0.3 yr which are statistically significant at the 99.7 per cent level. We derive upper limits for secular period changes of |dP/dt| < 3x10^{-12} and |dP/dt| < 1.8x10^{-11}, respectively for V2051 Oph and V4140 Sgr. We combined our results with those in the literature to construct a diagram of the amplitude versus period of the modulation for a sample of 11 eclipsing cataclysmic variables (CVs). If the cyclical period changes are the consequence of a solar-type magnetic activity cycle in the secondary star, then magnetic activity is a widespread phenomenon in CVs, being equally common among long- and short-period systems. This gives independent evidence that the magnetic field (and activity) of the secondary stars of CVs do not disappear when they become fully convective. We also find that the fractional cycle period changes of the short-period CVs are systematically smaller than those of the long-period CVs.Comment: 9 pages, 4 postscript figures, coded with MNRAS latex style file. To appear in Monthly Notices of the Royal Astronomical Societ