497 research outputs found

    V1135 Herculis: a double-lined eclipsing binary with an Anomalous Cepheid

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    BVR light curves and radial velocities for the double-lined eclipsing binary V1135\,Her were obtained. The brighter component of V1135\,Her is a Cepheid variable with a pulsation period of 4.22433±\pm0.00026 days. The orbital period of the system is about 39.99782±\pm0.00233 days, which is the shortest value among the known Type\,II Cepheid binaries. The observed B, V, and R magnitudes were cleaned for the intrinsic variations of the primary star. The remaining light curves, consisting of eclipses and proximity effects, are obtained. Our analyses of the multi-colour light curves and radial velocities led to the determination of fundamental stellar properties of both components of the interesting system V1135\,Her. The system consists of two evolved stars, G1+K3 between giants and supergiants, with masses of M1_1=1.461±\pm0.054 \Msun ~and M2_2=0.504±\pm0.040 {\Msun} and radii of R1_1=27.1±\pm0.4 {\Rsun} and R2_2=10.4±\pm0.2 {\Rsun}. The pulsating star is almost filling its corresponding Roche lobe which indicates the possibility of mass loss or transfer having taken place. We find an average distance of d=7500±\pm450 pc using the BVR magnitudes and also the V-band extinction. Location in the Galaxy and the distance to the galactic plane with an amount of 1300 pc indicate that it probably belongs to the thick-disk population. Most of the observed and calculated parameters of the V1135\,Her and its location on the color-magnitude and period-luminosity diagrams lead to a classification of an Anomalous Cepheid.Comment: 25 pages, 9 Tables, 9 Figures, Accepted Revista Mexicana de Astronom\'ia y Astrof\'isica. arXiv admin note: substantial text overlap with arXiv:1211.120

    Analytical, numerical, and experimental investigation of a Luneburg lens system for directional cloaking

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    In this study, the design of a directional cloaking based on the Luneburg lens system is proposed and its operating principle is experimentally verified. The cloaking concept is analytically investigated via geometrical optics and numerically realized with the help of the finite-difference time-domain method. In order to benefit from its unique focusing and/or collimating characteristics of light, the Luneburg lens is used. We show that by the proper combination of Luneburg lenses in an array form, incident light bypasses the region between junctions of the lenses, i.e., the "dark zone." Hence, direct interaction of an object with propagating light is prevented if one places the object to be cloaked inside that dark zone. This effect is used for hiding an object which is made of a perfectly electric conductor material. In order to design an implementable cloaking device, the Luneburg lens is discretized into a photonic crystal structure having gradually varying air cylindrical holes in a dielectric material by using Maxwell Garnett effective medium approximations. Experimental verifications of the designed cloaking structure are performed at microwave frequencies of around 8 GHz. The proposed structure is fabricated by three-dimensional printing of dielectric polylactide material and a brass metallic alloy is utilized in place of the perfectly electric conductor material in microwave experiments. Good agreement between numerical and experimental results is found. © 2019 American Physical Society

    Impact of Rescue-Thrombolysis during Cardiopulmonary Resuscitation in Patients with Pulmonary Embolism

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    Background: Cardiac arrest in patients with pulmonary embolism (PE) is associated with high morbidity and mortality. Thrombolysis is expected to improve the outcome in these patients. However studies evaluating rescue-thrombolysis in patients with PE are missing, mainly due to the difficulties of clinical diagnosis of PE. We aimed to determine the success influencing factors of thrombolysis during resuscitation in patients with PE. Methodology/Principal Findings: We analyzed retrospectively the outcome of 104 consecutive patients with confirmed (n = 63) or highly suspected (n = 41) PE and monitored cardiac arrest. In all patients rtPA was administrated for thrombolysis during cardiopulmonary resuscitation. In 40 of the 104 patients (38.5%) a return of spontaneous circulation (ROSC) could be achieved successfully. Patients with ROSC received thrombolysis significantly earlier after CPR onset compared to patients without ROSC (13.661.2 min versus 24.660.8 min; p,0.001). 19 patients (47.5%) out of the 40 patients with initially successful resuscitation survived to hospital discharge. In patients with hospital discharge thrombolysis therapy was begun with a significantly shorter delay after cardiac arrest compared to all other patients (11.061.3 vs. 22.560.9 min; p,0.001). Conclusion: Rescue-thrombolysis should be considered and started in patients with PE and cardiac arrest, as soon a

    Cardiac tumors in a tertiary care cancer hospital: clinical features, echocardiographic findings, treatment and outcomes

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    Cardiac tumors are a rare entity, comprised of tumors with diverse histology and natural history. We report the clinical characteristics, echocardiograhic findings, therapy and outcome of 59 patients with primary and metastatic cardiac tumors. Our institutional echocardiogram data base from 1993 through 2005 was reviewed to identify patients diagnosed with intra-cardiac tumor. A total of 59 patients with cardiac tumors were identified and included in the study. The patients' characteristics, presenting symptoms, diagnostic tests, location, histology of the tumor, treatment and the one year survival rate of this population was collected from the medical records. Of the 59 cardiac tumor cases, 16 (27%) were primary cardiac tumors and 43 (73%) were secondary cardiac tumors. The most common primary tumor was sarcoma affecting 13 (81%) of the 16 cases. Of these, 5 patients were angiosarcoma, 5 unclassified sarcoma, one myxoid sarcoma and 2 malignant fibrous histiocytoma. The mean age at presentation was 41.1 years, and the most common location was right atrium affecting 6 cases (37.5%). The most common symptom of dyspnea was present in 10 (62.5%) cases. Eleven (25.6%) of the 43 secondary cardiac tumors were metastasis from renal cell carcinoma. The mean age at presentation was 55.4 years. Right atrium was the most frequent location affecting 18 (42%) of the 43 patients. The most common presenting symptom was dyspnea in 15 (35%) cases. For both primary and secondary tumors, dyspnea was the most common symptom and right atrium was most frequently involved. Sarcoma was the most common primary cardiac tumor while metastasis from renal cell carcinoma was the most common secondary tumor

    CD20 and CD19 targeted vectors induce minimal activation of resting B lymphocytes

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    B lymphocytes are an important cell population of the immune system. However, until recently it was not possible to transduce resting B lymphocytes with retro- or lentiviral vectors, making them unsusceptible for genetic manipulations by these vectors. Lately, we demonstrated that lentiviral vectors pseudotyped with modified measles virus (MV) glycoproteins hemagglutinin, responsible for receptor recognition, and fusion protein were able to overcome this transduction block. They use either the natural MV receptors, CD46 and signaling lymphocyte activation molecule (SLAM), for cell entry (MV-LV) or the vector particles were further modified to selectively enter via the CD20 molecule, which is exclusively expressed on B lymphocytes (CD20-LV). It has been shown previously that transduction by MV-LV does not induce B lymphocyte activation. However, if this is also true for CD20-LV is still unknown. Here, we generated a vector specific for another B lymphocyte marker, CD19, and compared its ability to transduce resting B lymphocytes with CD20-LV. The vector (CD19ds-LV) was able to stably transduce unstimulated B lymphocytes, albeit with a reduced efficiency of about 10% compared to CD20-LV, which transduced about 30% of the cells. Since CD20 as well as CD19 are closely linked to the B lymphocyte activation pathway, we investigated if engagement of CD20 or CD19 molecules by the vector particles induces activating stimuli in resting B lymphocytes. Although, activation of B lymphocytes often involves calcium influx, we did not detect elevated calcium levels. However, the activation marker CD71 was substantially up-regulated upon CD20-LV transduction and most importantly, B lymphocytes transduced with CD20-LV or CD19ds-LV entered the G1b phase of cell cycle, whereas untransduced or MV-LV transduced B lymphocytes remained in G0. Hence, CD20 and CD19 targeting vectors induce activating stimuli in resting B lymphocytes, which most likely renders them susceptible for lentiviral vector transduction
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