11,331 research outputs found
Anchoring effects in the development of false childhood memories
When people receive descriptions or doctored photos of events that never happened, they often come to remember those events. But if people receive both a description and a doctored photo, does the order in which they receive the information matter? We asked people to consider a description and a doctored photograph of a childhood hot air balloon ride, and we varied which medium they saw first. People who saw a description first reported more false images and memories than people who saw a photo first, a result that fits with an anchoring account of false childhood memories
Manifestations of quantum holonomy in interferometry
Abelian and non-Abelian geometric phases, known as quantum holonomies, have
attracted considerable attention in the past. Here, we show that it is possible
to associate nonequivalent holonomies to discrete sequences of subspaces in a
Hilbert space. We consider two such holonomies that arise naturally in
interferometer settings. For sequences approximating smooth paths in the base
(Grassmann) manifold, these holonomies both approach the standard holonomy. In
the one-dimensional case the two types of holonomies are Abelian and coincide
with Pancharatnam's geometric phase factor. The theory is illustrated with a
model example of projective measurements involving angular momentum coherent
states.Comment: Some changes, journal reference adde
Reverse graded relaxed buffers for high Ge content SiGe virtual substrates
An innovative approach is proposed for epitaxial growth of high Ge content, relaxed Si1−xGex buffer layers on a Si(001) substrate. The advantages of the technique are demonstrated by growing such structures via chemical vapor deposition and their characterization. Relaxed Ge is first grown on the substrate followed by the reverse grading approach to reach a final buffer composition of 0.78. The optimized buffer structure is only 2.8 µm thick and demonstrates a low surface threading dislocation density of 4×106 cm−2, with a surface roughness of 2.6 nm. The buffers demonstrate a relaxation of up to 107%
Microflow leakage through the clearance of a metal-metal seal
The motivation behind this study is to simulate high pressure gas flow through the clearance between a valve seat and disc when in a closed position using a representative model. This leakage phenomenon is common in metal-to-metal seal pressure relief valves. As a pressure relief valve reaches the set pressure, it is known for the leakage to increase. The representative model that we studied is of an ideal-gas flow through a 2D micro-channel in the slip flow regime. We used a laminar continuum flow solver which solved the mass, momentum and energy equations. In addition, we applied low pressure slip boundary conditions at the wall boundaries which considered Maxwell's model for slip. The channel height was varied from 1μm to 5μm while the length remained at 1.25 mm, this means the length to height ratio varied from 1250 to 250. Inlet pressure was varied from a low pressure (0.05 MPa) to a high pressure (18.6 MPa), while the outlet remained constant at atmospheric. The calculated mass flow rate is compared to an analytical solution giving very good agreement for low pressure ratios and high length to height ratios
Insights from the 2006 Disease Management Colloquium
This roundtable discussion emanates from the presentations given and issues raised at the 2006 Disease Management Colloquium, which was held May 10–12, 2006 in Philadelphia, Pennsylvania
Tracking icebergs with time-lapse photography and sparse optical flow, LeConte Bay, Alaska, 2016–2017
We present a workflow to track icebergs in proglacial fjords using oblique time-lapse photos
and the Lucas-Kanade optical flow algorithm. We employ the workflow at LeConte Bay, Alaska, where we ran five time-lapse cameras between April 2016 and September 2017, capturing more than 400 000 photos at frame rates of 0.5–4.0 min−1. Hourly to daily average velocity fields in map coordinates illustrate dynamic currents in the bay, with dominant downfjord velocities (exceeding 0.5 m s−1 intermittently) and several eddies. Comparisons with simultaneous Acoustic Doppler Current Profiler (ADCP) measurements yield best agreement for the uppermost ADCP levels (∼ 12 m and above), in line with prevalent small icebergs that trace near-surface currents. Tracking results from multiple cameras compare favorably, although cameras with lower frame rates (0.5 min−1) tend to underestimate high flow speeds. Tests to determine requisite temporal and spatial image resolution confirm the importance of high image frame rates, while spatial resolution is of secondary importance. Application of our procedure to other fjords will be successful if iceberg concentrations are high enough and if the camera frame rates are sufficiently rapid (at least 1 min−1 for conditions similar to LeConte Bay).This work was funded by the U.S. National Science Foundation (OPP-1503910, OPP-1504288, OPP-1504521 and OPP-1504191).Ye
Scientific Assessment of Ozone Depletion: 2014 - Twenty Questions and Answers About the Ozone Layer: 2014 Update
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