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- Crossfield, Ian J. M., et al.
(författare)
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197 CANDIDATES AND 104 VALIDATED PLANETS IN K2's FIRST FIVE FIELDS
- 2016
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Ingår i: Astrophysical Journal Supplement Series. - : American Astronomical Society. - 0067-0049 .- 1538-4365. ; 226:1
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Tidskriftsartikel (refereegranskat)abstract
- We present 197 planet candidates discovered using data from the first year of the NASA K2 mission (Campaigns 0-4), along with the results of an intensive program of photometric analyses, stellar spectroscopy, high-resolution imaging, and statistical validation. We distill these candidates into sets of 104 validated planets (57 in multi-planet systems), 30 false positives, and 63 remaining candidates. Our validated systems span a range of properties, with median values of R-P = 2.3 R-circle plus, P = 8.6 days, T-eff = 5300 K, and Kp = 12.7 mag. Stellar spectroscopy provides precise stellar and planetary parameters for most of these systems. We show that K2 has increased by 30% the number of small planets known to orbit moderately bright stars (1-4 R-circle plus, Kp = 9-13. mag). Of particular interest are 76 planets smaller than 2 R-circle plus, 15 orbiting stars brighter than Kp = 11.5. mag, 5 receiving Earth-like irradiation levels, and several multi-planet systems-including 4 planets orbiting the M dwarf K2-72 near mean-motion resonances. By quantifying the likelihood that each candidate is a planet we demonstrate that our candidate sample has an overall false positive rate of 15%-30%, with rates substantially lower for small candidates (<2 R-circle plus) and larger for candidates with radii >8 R-circle plus and/or with P < 3 days. Extrapolation of the current planetary yield suggests that K2 will discover between 500 and 1000 planets in its planned four-year mission, assuming sufficient follow-up resources are available. Efficient observing and analysis, together with an organized and coherent follow-up strategy, are essential for maximizing the efficacy of planet-validation efforts for K2, TESS, and future large-scale surveys.
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- Staubitz, J. I., et al.
(författare)
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EUROCRINE® : Nebennierenoperationen 2015 bis 2019 – überraschende erste Ergebnisse
- 2021
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Ingår i: Der Chirurg. - : Springer Science and Business Media LLC. - 0009-4722 .- 1433-0385. ; 92:5, s. 448-463
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Tidskriftsartikel (refereegranskat)abstract
- Background: Since 2015 operations performed in the field of endocrine surgery have been entered into the European registry EUROCRINE®. The aim of this analysis was a description of the current healthcare situation for adrenal surgery in a homogeneous healthcare environment corresponding to the German-speaking countries—or to the presence of the working group on surgical endocrinology (CAEK) of the German society for general and visceral surgery (DGAV)—and to assess the adherence to current international treatment guidelines. Methods: An analysis of the preoperative diagnostics, the applied operative techniques and the underlying histological entities was carried out for all operations on adrenal glands in Germany, Switzerland and Austria, which were registered in EUROCRINE® from 2015 to 2019. Results: In the total of 21 participating hospitals from the German-speaking EUROCRINE® countries, 658 operations on adrenal glands were performed. In 90% of cases unilateral adrenalectomy was performed, in 3% bilateral adrenalectomy and in 7% other resection procedures. In 41% the main histological diagnosis was an adrenocortical adenoma. In 15% malignant entities were detected on final histology, including 6% adrenocortical carcinoma (ACC) and 8% metastases to the adrenal glands. 23% of the operations were performed for pheochromocytoma. This entity was primarily resected using minimally invasive approaches (82%), whereas minimally invasive techniques were applied in 28% for ACC and in 66% for metastases to the adrenal glands. Conclusion: Surprisingly, following adrenocortical adenoma and pheochromocytoma, the third most common histological entity was metastasis of different extra-adrenal primary tumors to the adrenal gland. Of the operations for ACC 28% were scheduled for minimally invasive techniques, but conversion to open surgery was necessary in 20%. The analysis revealed discrepancies between treatment reality and international guideline recommendations that raise questions, which will be addressed by an updated version of the EUROCRINE® module for the documentation of adrenal surgery.
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- Martinez, Arturo O., et al.
(författare)
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Stellar and Planetary Parameters for K2's Late-type Dwarf Systems from C1 to C5
- 2017
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 837:1
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Tidskriftsartikel (refereegranskat)abstract
- The NASA K2 mission uses photometry to find planets transiting stars of various types. M dwarfs are of high interest since they host more short-period planets than any other type of main-sequence star and transiting planets around M dwarfs have deeper transits compared to other main-sequence stars. In this paper, we present stellar parameters from K and M dwarfs hosting transiting planet candidates discovered by our team. Using the SOFI spectrograph on the European Southern Observatory's New Technology Telescope, we obtained R approximate to 1000 J-, H-, and K-band (0.95-2.52 mu m) spectra of 34 late-type K2 planet and candidate planet host systems and 12 bright K4-M5 dwarfs with interferometrically measured radii and effective temperatures. Out of our 34 late-type K2 targets, we identify 27 of these stars as M dwarfs. We measure equivalent widths of spectral features, derive calibration relations using stars with interferometric measurements, and estimate stellar radii, effective temperatures, masses, and luminosities for the K2 planet hosts. Our calibrations provide radii and temperatures with median uncertainties of 0.059 R-circle dot (16.09%) and 160 K (4.33%), respectively. We then reassess the radii and equilibrium temperatures of known and candidate planets based on our spectroscopically derived stellar parameters. Since a planet's radius and equilibrium temperature depend on the parameters of its host star, our study provides more precise planetary parameters for planets and candidates orbiting late-type stars observed with K2. We find a median planet radius and an equilibrium temperature of approximately 3 R-circle plus and 500 K, respectively, with several systems (K2-18b and K2-72e) receiving near-Earth-like levels of incident irradiation.
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- Schiffer, M., et al.
(författare)
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Micro mass flow controller for a mini-HCCI-motor driven power generator
- 2007
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Ingår i: TRANSDUCERS 2007 - 2007 International Solid-State Sensors, Actuators and Microsystems Conference. - 1424408423 - 9781424408429 ; , s. 1127-1130
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Konferensbidrag (refereegranskat)abstract
- A piezoelectric micro mass flow controller (MMFC) for liquid fuel injection into a mini-HCCI-motor for power generation is introduced. Piezoelectric actuation ensures negligible power consumption for fuel injection allowing self-sustaining operation. A pressurized fuel tank is connected to the MMFC which is designed like a normally-closed, on-/off-operating valve. Integrated piezoresistors are used for feedback control and an implemented pn-diode (sensitivity: -2.5 mV/K) enables on-chip temperature monitoring. Flow rates of up to 70 μl/s at 100 kPa fuel pressure have been demonstrated. The power consumption of the piezoelectric actuator during steady state operation is max. 20 μW at 120 V.
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