1,324 research outputs found

    UBVRI photopolarimetry of the long period eclipsing AM Herculis binary V1309

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    We report simultaneous UBVRI photo-polarimetric observations of the long period (7.98 h) AM Her binary V1309 Ori. The length and shape of the eclipse ingress and egress varies from night to night. We suggest this is due to the variation in the brightness of the accretion stream. By comparing the phases of circular polarization zero-crossovers with previous observations, we confirm that V1309 Ori is well synchronized, and find an upper limit of 0.002 percent for the difference between the spin and orbital periods. We model the polarimetry data using a model consisting of two cyclotron emission regions at almost diametrically opposite locations, and centered at colatitude 35 (deg) and 145 (deg) on the surface of the white dwarf. We also present archive X-ray observations which show that the negatively polarised accretion region is X-ray bright.Comment: 11 pages, 12 figures (2 colour), Fig1 and Fig 4 are in lower resolution than in original paper, accepted for publication in Monthly Notices of the Royal Astronomical Societ

    Black Mesoporous Silicon as a Contrast Agent for LED-Based 3D Photoacoustic Tomography

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    Mesoporous silicon (PSi) nanoparticles have been widely studied in different biomedical imaging modalities due to their several beneficial material properties. However, they have not been found to be suitable for photoacoustic imaging due to their poor photothermal conversion performance. In the present study, biodegradable black mesoporous silicon (BPSi) nanoparticles with strong light absorbance were developed as superior image contrast agents for photoacoustic tomography (PAT), which was realized with a light-emitting diode (LED) instead of the commonly used laser. LED-based PAT offers the advantages of low cost, compactness, good mobility, and easy operation as compared to the traditional laser-based PAT modality. Nevertheless, the poor imaging sensitivity of the LED-PAT systems has been the main barrier to prevent their wide biomedical application because the LED light has low optical energy. The present study demonstrated that the imaging sensitivity of the LED-PAT system was significantly enhanced with the PEGylated BPSi (PEG–BPSi) nanoparticles. The PEG–BPSi nanoparticles were clearly detectable with a low concentration of 0.05 mg/mL in vitro and with an LED radiation energy of 5.2 μJ. The required concentration of the PEG–BPSi nanoparticles was 10 times lesser than that of the reference gold nanoparticles to reach the corresponding level of the imaging contrast. The ex vivo studies demonstrated that the submillimeter BPSi nanoparticle-based absorbers were distinguishable in chicken breast tissues. The strong contrast provided by the BPSi particles indicated that these particles can be utilized as novel contrast agents in PAT, especially in LED-based systems with low light intensity

    Baltic Ecological Recycling Agriculture and Society (BERAS project) - a case of Juva milk system

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    The aim of the study was to determine the potential, impact and prerequisites of localization and enhanced recycling in a rural food system, illustrated by the case of Juva milk. An interdisciplinary scenario based on the increase of local, organic milk to 50 % of milk comsumption was created and the sustainability was compared, on the basis of the statistics and data collected from the actors, with the present milk system

    The association between bacterial infections and the risk of coronary heart disease in type 1 diabetes

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    Background Diabetes increases the risk of infections as well as coronary heart disease (CHD). Whether infections increase the risk of CHD and how this applies to individuals with diabetes is unclear. Objectives To investigate the association between bacterial infections and the risk of CHD in type 1 diabetes. Methods Individuals with type 1 diabetes (n = 3781) were recruited from the Finnish Diabetic Nephropathy Study (FinnDiane), a prospective follow-up study. CHD was defined as incident events: fatal or non-fatal myocardial infarction, coronary artery bypass surgery or percutaneous coronary intervention, identified through national hospital discharge register data. Infections were identified through national register data on all antibiotic purchases from outpatient care. Register data were available from 1.1.1995-31.12.2015. Bacterial lipopolysaccharide (LPS) activity was measured from serum samples at baseline. Data on traditional risk factors for CHD were collected during baseline and consecutive visits. Results Individuals with an incident CHD event (n = 370) had a higher mean number of antibiotic purchases per follow-up year compared to those without incident CHD (1.34 [95% CI: 1.16-1.52], versus 0.79 [0.76-0.82],P <0.001), as well as higher levels of LPS activity (0.64 [0.60-0.67], versus 0.58 EU mL(-1)[0.57-0.59],P <0.001). In multivariable-adjusted Cox proportional hazards models, the mean number of antibiotic purchases per follow-up year was an independent risk factor for incident CHD (HR 1.21, 95% CI: 1.14-1.29,P <0.0001). High LPS activity was a risk factor for incident CHD (HR 1.93 [1.34-2.78],P <0.001) after adjusting for static confounders. Conclusion Bacterial infections are associated with an increased risk of incident CHD in individuals with type 1 diabetes.Peer reviewe

    Quasisymmetric graphs and Zygmund functions

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    A quasisymmetric graph is a curve whose projection onto a line is a quasisymmetric map. We show that this class of curves is related to solutions of the reduced Beltrami equation and to a generalization of the Zygmund class Λ\Lambda_*. This relation makes it possible to use the tools of harmonic analysis to construct nontrivial examples of quasisymmetric graphs and of quasiconformal maps.Comment: 21 pages, no figure

    Menelaus' theorem, Clifford configurations and inversive geometry of the Schwarzian KP hierarchy

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    It is shown that the integrable discrete Schwarzian KP (dSKP) equation which constitutes an algebraic superposition formula associated with, for instance, the Schwarzian KP hierarchy, the classical Darboux transformation and quasi-conformal mappings encapsulates nothing but a fundamental theorem of ancient Greek geometry. Thus, it is demonstrated that the connection with Menelaus' theorem and, more generally, Clifford configurations renders the dSKP equation a natural object of inversive geometry on the plane. The geometric and algebraic integrability of dSKP lattices and their reductions to lattices of Menelaus-Darboux, Schwarzian KdV, Schwarzian Boussinesq and Schramm type is discussed. The dSKP and discrete Schwarzian Boussinesq equations are shown to represent discretizations of families of quasi-conformal mappings.Comment: 26 pages, 9 figure

    Temperature effects on dislocation core energies in silicon and germanium

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    Temperature effects on the energetics of the 90-degree partial dislocation in silicon and germanium are investigated, using non-equilibrium methods to estimate free energies, coupled with Monte Carlo simulations. Atomic interactions are described by Tersoff and EDIP interatomic potentials. Our results indicate that the vibrational entropy has the effect of increasing the difference in free energy between the two possible reconstructions of the 90-degree partial, namely, the single-period and the double-period geometries. This effect further increases the energetic stability of the double-period reconstruction at high temperatures. The results also indicate that anharmonic effects may play an important role in determining the structural properties of these defects in the high-temperature regime.Comment: 8 pages in two-column physical-review format with six figure

    Are coronary event rates declining slower in women than in men – evidence from two population-based myocardial infarction registers in Finland?

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    <p>Abstract</p> <p>Background</p> <p>Studies have suggested that the prevention and treatment of coronary heart disease may not have been as effective in women as in men. Therefore, we aimed to examine whether the incidence, attack rate and mortality of myocardial infarction (MI) events have declined less in women than in men.</p> <p>Methods</p> <p>Two large population-based MI registers, the FINAMI register and the Finnish Cardiovascular Disease Register (CVDR) were used for comparing the event rates among men and women aged ≥35 years in two time periods, 1994–1996 and 2000–2002.</p> <p>Results</p> <p>In the FINAMI register a total of 5,252 events were recorded in men and 4,898 in women. Corresponding numbers in the CVDR were 78,709 and 70,464. Both FINAMI and CVDR data suggested smaller declines in incidence and attack rate of MI events in women than in men. In CVDR data the decline in mortality was also smaller in women than in men, while in FINAMI data this difference did not reach statistical significance. In the large CVDR data set, negative binomial regression models revealed smaller declines in incidence (p = 0.006), attack rate (p = 0.008) and mortality (p = 0.04) in women than in men aged <55 years. In persons ≥55 years no difference was observed between women and men.</p> <p>Conclusion</p> <p>The incidence and attack rate of MI events have declined less in women aged <55 than in men of similar age. In older persons no significant differences were observed. Further studies are warranted to find out the reasons why the development has been less favourable for young women than for men.</p
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