32,843 research outputs found
Stokes flow in a drop evaporating from a liquid subphase
The evaporation of a drop from a liquid subphase is investigated. The two
liquids are immiscible, and the contact angles between them are given by the
Neumann construction. The evaporation of the drop gives rise to flows in both
liquids, which are coupled by the continuity of velocity and shear-stress
conditions. We derive self-similar solutions to the velocity fields in both
liquids close to the three-phase contact line, where the drop geometry can be
approximated by a wedge. We focus on the case where Marangoni stresses are
negligible, for which the flow field consists of three contributions: flow
driven by the evaporative flux from the drop surface, flow induced by the
receding motion of the contact line, and an eigenmode flow that satisfies the
homogeneous boundary conditions. The eigenmode flow is asymptotically
subdominant for all contact angles. The moving contact-line flow dominates when
the angle between the liquid drop and the horizontal surface of the liquid
subphase is smaller than , while the evaporative-flux driven flow
dominates for larger angles. A parametric study is performed to show how the
velocity fields in the two liquids depend on the contact angles between the
liquids and their viscosity ratio.Comment: submitted to Physics of Fluid
Fine needle aspiration cytology of hepatic metastases of neuroendocrine tumors: A 20‐year retrospective, single institutional study
Background
Fine needle aspiration (FNA) is considered an excellent technique for documenting metastatic neuroendocrine tumors (NETs). This study aims to evaluate the accuracy of FNA in diagnosing metastatic NETs to the liver and determining the grade and origin of these metastases.
Methods
Our laboratory information system was searched from 1997 to 2016 to identify all cases of metastatic NETs to the liver that were sampled by FNA. The cytopathology and surgical pathology reports as well as the patients' electronic medical records were reviewed. The cytohistologic type and grade of the metastatic NETs, as well as the site of the patient's primary were recorded.
Results
High‐grade NETs, including small cell and poorly differentiated neuroendocrine carcinomas, constituted 62% (167/271) of the cases, while low‐grade NETs, including well differentiated NET (grade1 and grade 2), pheochromocytomas, paragangliomas, and carcinoid tumors of lung, constituted 38% (104/271) of cases. The most common diagnosis was metastatic small cell carcinoma accounting for 45% (122/271) of cases. The most common primary sites were lung (44%; 119/271) followed by pancreas (19%; 51/271). The FNA diagnosis was confirmed by histopathology in 121 cases that had a concurrent biopsies or resection specimens.
Conclusions
FNA is an accurate method for diagnosing metastatic NETs to the liver. There were significantly more high‐grade (62%) than low‐grade (38%) metastatic NETs to the liver. In our practice, lung (44%) and pancreas (19%) were the most common primary sites of metastatic NETs involving the liver. In 16% of the cases, a primary site could not be established
Tight Noise Thresholds for Quantum Computation with Perfect Stabilizer Operations
We study how much noise can be tolerated by a universal gate set before it
loses its quantum-computational power. Specifically we look at circuits with
perfect stabilizer operations in addition to imperfect non-stabilizer gates. We
prove that for all unitary single-qubit gates there exists a tight depolarizing
noise threshold that determines whether the gate enables universal quantum
computation or if the gate can be simulated by a mixture of Clifford gates.
This exact threshold is determined by the Clifford polytope spanned by the 24
single-qubit Clifford gates. The result is in contrast to the situation wherein
non-stabilizer qubit states are used; the thresholds in that case are not
currently known to be tight.Comment: 4 pages, 2 figure
Long-Period Giant Companions to Three Compact, Multiplanet Systems
Understanding the relationship between long-period giant planets and multiple smaller short-period planets is critical for formulating a complete picture of planet formation. This work characterizes three such systems. We present Kepler-65, a system with an eccentric (e = 0.28 ± 0.07) giant planet companion discovered via radial velocities (RVs) exterior to a compact, multiply transiting system of sub-Neptune planets. We also use precision RVs to improve mass and radius constraints on two other systems with similar architectures, Kepler-25 and Kepler-68. In Kepler-68 we propose a second exterior giant planet candidate. Finally, we consider the implications of these systems for planet formation models, particularly that the moderate eccentricity in Kepler-65\u27s exterior giant planet did not disrupt its inner system
The investigation of vertebral injury sustained during aircrew ejection. Phase 2a - Basic science experimental design and investigation of dynamic characteristics of vertebral columns considered as an engineering structure Annual report, 1 Nov. 1966 - 31 Oct. 1967
Dynamic strength studies on human vertebrae for correlation with data on effects of forcible ejection from disabled aircraf
Swift/UVOT Photometry of the Planetary Nebula WeBo 1: Unmasking A Faint Hot Companion Star
We present an analysis of over 150 ks of data on the planetary nebula WeBo 1
(PN G135.6+01.0) obtained with the Swift Ultraviolet Optical Telescope (UVOT).
The central object of this nebula has previously been described as a late-type
K giant barium star with a possible hot companion, most likely a young
pre-white dwarf. UVOT photometry shows that while the optical photometry is
consistent with a large cool object, the near-ultraviolet (UV) photometry shows
far more UV flux than could be produced by any late-type object. Using model
stellar atmospheres and a comparison to UVOT photometry for the pre-white dwarf
PG 1159-035, we find that the companion has a temperature of at least 40,000 K
and a radius of, at most, 0.056 R_sun. While the temperature and radius are
consistent with a hot compact stellar remnant, they are lower and larger,
respectively, than expected for a typical young pre-white dwarf. This likely
indicates a deficiency in the assumed UV extinction curve. We find that higher
temperatures more consistent with expectations for a pre-white dwarf can be
derived if the foreground dust has a strong "blue bump" at 2175 AA and a lower
R_V. Our results demonstrate the ability of Swift to both uncover and
characterize hot hidden companion stars and to constrain the UV extinction
properties of foreground dust based solely on UVOT photometry.Comment: 26 pages, 9 figure, accepted to Astronomical Journa
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