1,751 research outputs found

    Invariants of Artinian Gorenstein Algebras and Isolated Hypersurface Singularities

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    We survey our recently proposed method for constructing biholomorphic invariants of quasihomogeneous isolated hypersurface singularities and, more generally, invariants of graded Artinian Gorenstein algebras. The method utilizes certain polynomials associated to such algebras, called nil-polynomials, and we compare them with two other classes of polynomials that have also been used to produce invariants.Comment: 13 page

    A correlation between infrared excess and period for Mira variables

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    The [8.7]-[11.4] infrared color is found to increase monotonically with increasing period for a sample of 41 Mira variables. We conclude that mass loss is not a stochastic process and that for any Mira variable the rate of mass loss is directly linked to the parameters which dictate the period of that variable

    Program on Earth Observation Data Management Systems (EODMS), appendixes

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    The needs of state, regional, and local agencies involved in natural resources management in Illinois, Iowa, Minnesota, Missouri, and Wisconsin are investigated to determine the design of satellite remotely sensed derivable information products. It is concluded that an operational Earth Observation Data Management System (EODMS) will be most beneficial if it provides a full range of services - from raw data acquisition to interpretation and dissemination of final information products. Included is a cost and performance analysis of alternative processing centers, and an assessment of the impacts of policy, regulation, and government structure on implementing large scale use of remote sensing technology in this community of users

    Delta-9-tetrahydrocannabinol protects against MPP+ toxicity in SH-SY5Y cells by restoring proteins involved in mitochondrial biogenesis

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    This project was supported through a studentship awarded by the Plymouth University Peninsula Schools of Medicine and Dentistry.Proliferator-activated receptor γ (PPARγ) activation can result in transcription of proteins involved in oxidative stress defence and mitochondrial biogenesis which could rescue mitochondrial dysfunction in Parkinson's disease (PD).The PPARγ agonist pioglitazone is protective in models of PD; however side effects have limited its clinical use. The cannabinoid Δ9-tetrahydrocannabinol (Δ9-THC) may have PPARγ dependent anti-oxidant properties. Here we investigate the effects of Δ9-THC and pioglitazone on mitochondrial biogenesis and oxidative stress. Differentiated SH-SY5Y neuroblastoma cells were exposed to the PD relevant mitochondrial complex 1 inhibitor 1-methyl- 4-phenylpyridinium iodide (MPP+). We found that only Δ9-THC was able to restore mitochondrial content in MPP+ treated SH-SY5Y cells in a PPARγ dependent manner by increasing expression of the PPARγ co-activator 1a (PGC-1a), the mitochondrial transcription factor (TFAM) as well as mitochondrial DNA content. Co-application of Δ9- THC with pioglitazone further increased the neuroprotection against MPP+ toxicity as compared to pioglitazone treatment alone. Furthermore, using lentiviral knock down of the PPARγ receptor we showed that, unlike pioglitazone, Δ9-THC resulted in a PPARγ dependent reduction of MPP+ induced oxidative stress. We therefore suggest that, in contrast to pioglitazone, Δ9-THC mediates neuroprotection via PPARγ-dependent restoration of mitochondrial content which may be beneficial for PD treatment.Publisher PDFPeer reviewe

    Program on Earth Observation Data Management Systems (EODMS)

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    An assessment was made of the needs of a group of potential users of satellite remotely sensed data (state, regional, and local agencies) involved in natural resources management in five states, and alternative data management systems to satisfy these needs are outlined. Tasks described include: (1) a comprehensive data needs analysis of state and local users; (2) the design of remote sensing-derivable information products that serve priority state and local data needs; (3) a cost and performance analysis of alternative processing centers for producing these products; (4) an assessment of the impacts of policy, regulation and government structure on implementing large-scale use of remote sensing technology in this community of users; and (5) the elaboration of alternative institutional arrangements for operational Earth Observation Data Management Systems (EODMS). It is concluded that an operational EODMS will be of most use to state, regional, and local agencies if it provides a full range of information services -- from raw data acquisition to interpretation and dissemination of final information products

    On the Brightness and Waiting-time Distributions of a Type III Radio Storm observed by STEREO/WAVES

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    Type III solar radio storms, observed at frequencies below approximately 16 MHz by space borne radio experiments, correspond to the quasi-continuous, bursty emission of electron beams onto open field lines above active regions. The mechanisms by which a storm can persist in some cases for more than a solar rotation whilst exhibiting considerable radio activity are poorly understood. To address this issue, the statistical properties of a type III storm observed by the STEREO/WAVES radio experiment are presented, examining both the brightness distribution and (for the first time) the waiting-time distribution. Single power law behavior is observed in the number distribution as a function of brightness; the power law index is approximately 2.1 and is largely independent of frequency. The waiting-time distribution is found to be consistent with a piecewise-constant Poisson process. This indicates that during the storm individual type III bursts occur independently and suggests that the storm dynamics are consistent with avalanche type behavior in the underlying active region.Comment: 14 pages, 4 figures, 1 table. Accepted for publication in Astrophysical Journal Letter

    Pulse Pressure Relationships with Demographics and Kidney Function in Ashanti, Ghana

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    Introduction. Hypertension, particularly pulse pressure [PP] is a major risk factor for end-stage renal disease. However, the effect of individual components of hypertension namely PP, systolic [SBP] and diastolic blood pressure [DBP] on kidney function, in the general African population is unknown. Methods. Data were collected on 944 participants [aged 40-75 y], living in villages in the area around the city of Kumasi, Ghana, on demographics, medications, height, weight, BP and 24-hour creatinine clearance (CrCl). Results. The demographic and clinical characteristics were: age 55(11) [mean (SD)] years, females 62%, rural village-dwellers 52%, diabetes 1·5%, BMI 21(4) kg/m2, 24-hourCrCl as a measure of glomerular filtration rate (GFR) 84(23) ml/min/1.73 m2. 29% had BP >140/90 mmHg; SBP and DBP were 125/74(26/14) mmHg, PP was 51(17) mmHg. PP increased with age by 0.55(95% CI: 0.46,0.64) mmHg/year. PP was higher (53(17) v 49(15) mmHg; p < 0.001) in the semiurban participants. GFR decreased both with increasing PP [-0.19 (-0.27,-0.10 ml/min/1.73 m2/mmHg; p < 0.001] and SBP [-0.09 (-0.14,-0.03) ml/min/1.73 m2/mmHg; p < 0.001] but there was no significant relationship with DBP [-0.04 (-0.15,0.06)]. After adjusting for SBP, the relationship between GFR and PP became steeper [-0.31 (-0.50,-0.12) ml/min/1.73 m2/mmHg; p < 0.001]. Using multivariate regression analysis that included PP, age, gender, BMI, only increasing age [-0.75 (-0.88,-0.62)] and decreasing BMI [0.49 (0.16,0.81)] were associated with decreased kidney function. Conclusions. In this homogeneous West-African population, PP increased with age and had a steeper relationship with declining kidney function than SBP or DBP

    A simultaneous search for prompt radio emission associated with the short GRB 170112A using the all-sky imaging capability of the OVRO-LWA

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    We have conducted the most sensitive low frequency (below 100 MHz) search to date for prompt, low-frequency radio emission associated with short-duration gamma-ray bursts (GRBs), using the Owens Valley Radio Observatory Long Wavelength Array (OVRO-LWA). The OVRO-LWA's nearly full-hemisphere field-of-view (∼20\sim20,000000 square degrees) allows us to search for low-frequency (sub-100100 MHz) counterparts for a large sample of the subset of GRB events for which prompt radio emission has been predicted. Following the detection of short GRB 170112A by Swift, we used all-sky OVRO-LWA images spanning one hour prior to and two hours following the GRB event to search for a transient source coincident with the position of GRB 170112A. We detect no transient source, with our most constraining 1σ1\sigma flux density limit of 650 mJy650~\text{mJy} for frequencies spanning 27 MHz−84 MHz27~\text{MHz}-84~\text{MHz}. We place constraints on a number of models predicting prompt, low-frequency radio emission accompanying short GRBs and their potential binary neutron star merger progenitors, and place an upper limit of Lradio/Lγ≲7×10−16L_\text{radio}/L_\gamma \lesssim 7\times10^{-16} on the fraction of energy released in the prompt radio emission. These observations serve as a pilot effort for a program targeting a wider sample of both short and long GRBs with the OVRO-LWA, including bursts with confirmed redshift measurements which are critical to placing the most constraining limits on prompt radio emission models, as well as a program for the follow-up of gravitational wave compact binary coalescence events detected by advanced LIGO and Virgo.Comment: 14 pages, 5 figures, ApJ submitte
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