432 research outputs found
Frank Burnett Dains and his History of Chemistry Collections at the University of Kansas
This paper was presented at the Bolton Society Symposium, Notable Antiquarian Chemistry Book Collectors and their Public Collections, at the 222nd American Chemical Society National Meeting, Division of the History of Chemistry in Chicago, Illinois, August 28, 2001.The history of chemistry collections that Frank Burnett Dains (1869-1948) amassed before and during his thirty plus years as Professor of Organic Chemistry at the University of Kansas have and continue to influence the faculty, students and staff at there. As a member of the American Chemical Society for more than fifty years, Dains was particularly active in the divisions of Chemical Education and the History of Chemistry. Chemists and historians of chemistry throughout the world have also benefited by Dains's collections and will continue to into the future in ways in which this paper will explain. Special emphasis will be placed on Dains's image collection, which is located in University Archives at the University of Kansas
From the margins to the mainstream: deconstructing science communication as a white, Western paradigm
In this commentary we are concerned with what mainstream science communication has neglected through cultural narrowness and ambient racism: other practitioners, missing audiences, unvalued knowledge, unrecognised practices. We explore examples from First Nations Peoples in the lands now known as Australia, from Griots in West Africa and from People's Science Movements in India to help us reimagine science communication. To develop meaningfully inclusive approaches to science communication, we argue there is an urgent need for the âmainstreamâ to recognise, value and learn from science communication practices that are all too often seen as at âthe marginsâ of this field
Microwave response of vortices in superconducting thin films of Re and Al
Vortices in superconductors driven at microwave frequencies exhibit a
response related to the interplay between the vortex viscosity, pinning
strength, and flux creep effects. At the same time, the trapping of vortices in
superconducting microwave resonant circuits contributes excess loss and can
result in substantial reductions in the quality factor. Thus, understanding the
microwave vortex response in superconducting thin films is important for the
design of such circuits, including superconducting qubits and photon detectors,
which are typically operated in small, but non-zero, magnetic fields. By
cooling in fields of the order of 100 T and below, we have characterized
the magnetic field and frequency dependence of the microwave response of a
small density of vortices in resonators fabricated from thin films of Re and
Al, which are common materials used in superconducting microwave circuits.
Above a certain threshold cooling field, which is different for the Re and Al
films, vortices become trapped in the resonators. Vortices in the Al resonators
contribute greater loss and are influenced more strongly by flux creep effects
than in the Re resonators. This different behavior can be described in the
framework of a general vortex dynamics model.Comment: Published in Physical Review B 79,174512(2009); preprint version with
higher resolution figures available at
http://physics.syr.edu/~bplourde/bltp-publications.ht
Generation of Three-Qubit Entangled States using Superconducting Phase Qubits
Entanglement is one of the key resources required for quantum computation, so
experimentally creating and measuring entangled states is of crucial importance
in the various physical implementations of a quantum computer. In
superconducting qubits, two-qubit entangled states have been demonstrated and
used to show violations of Bell's Inequality and to implement simple quantum
algorithms. Unlike the two-qubit case, however, where all maximally-entangled
two-qubit states are equivalent up to local changes of basis, three qubits can
be entangled in two fundamentally different ways, typified by the states
and . Here we demonstrate the operation of three coupled
superconducting phase qubits and use them to create and measure
and states. The states are fully characterized
using quantum state tomography and are shown to satisfy entanglement witnesses,
confirming that they are indeed examples of three-qubit entanglement and are
not separable into mixtures of two-qubit entanglement.Comment: 9 pages, 5 figures. Version 2: added supplementary information and
fixed image distortion in Figure 2
Assessment of holographic microscopy for quantifying marine particle size and concentration
Holographic microscopy has emerged as a tool for in situ imaging of microscopic organisms and other particles in the marine environment: appealing because of the relatively larger sampling volume and simpler optical configuration compared to other imaging systems. However, its quantitative capabilities have so far remained uncertain, in part because hologram reconstruction and image recognition have required manual operation. Here, we assess the quantitative skill of our automated hologram processing pipeline (CCV Pipeline), to evaluate the size and concentration measurements of environmental and cultured assemblages of marine plankton particles, and microspheres. Over 1 million particles, ranging from 10 to 200âÎŒm in equivalent spherical diameter, imaged by the 4âDeep HoloSea digital inline holographic microscope (DIHM) are analyzed. These measurements were collected in parallel with a FlowCam (FC), Imaging FlowCytobot (IFCB), and manual microscope identification. Once corrections for particle location and nonuniform illumination were developed and applied, the DIHM showed an underestimate in ESD of about 3% to 10%, but successfully reproduced the size spectral slope from environmental samples, and the size distribution of cultures (Dunaliella tertiolecta, Heterosigma akashiwo, and Prorocentrum micans) and microspheres. DIHM concentrations (order 1 to 1000 particles mlâ1) showed a linear agreement (r2 = 0.73) with the other instruments, but individual comparisons at times had large uncertainty. Overall, we found the DIHM and the CCV Pipeline required extensive manual correction, but once corrected, provided concentration and size estimates comparable to the other imaging systems assessed in this study. Holographic cameras are mechanically simple, autonomous, can operate at very high pressures, and provide a larger sampling volume than comparable lensâbased tools. Thus, we anticipate that these characterization efforts will be rewarded with novel discovery in new oceanic environments
Calibration of the Tip of the Red Giant Branch (TRGB)
The Tip of the Red Giant (TRGB) method provides one of the most accurate and
precise means of measuring the distances to nearby galaxies. Here we present a
VIJHK absolute calibration of the TRGB based on observations of TRGB stars in
the Large Magellanic Cloud (LMC),grounded on detached eclipsing binaries
(DEBs). This paper presents a more detailed description of the method first
presented in Freedman et al. (2019) for measuring corrections for the total
line-of-sight extinction and reddening to the LMC. In this method, we use a
differential comparison of the red giant population in the LMC, first with red
giants in the Local Group galaxy, IC 1613, and then with those in the Small
Magellanic Cloud. As a consistency check, we derive an independent calibration
of the TRGB sequence using the SMC alone, invoking its geometric distance also
calibrated by DEBs. An additional consistency check comes from near-infrared
observations of Galactic globular clusters covering a wide range of
metallicities. In all cases we find excellent agreement in the zero-point
calibration. We then examine the recent claims by Yuan et al. (2019),
demonstrating that, in the case of the SMC, they corrected for extinction alone
while neglecting the essential correction for reddening as well. In the case of
IC 1613, we show that their analysis contains an incorrect treatment of
(over-correction for) metallicity. Using our revised (and direct) measurement
of the LMC TRGB extinction, we find a value of Ho = 69.6 +/-0.8 (+/-1.1% stat)
+/- 1.7 (+/-2.4% sys) km/s/Mpc.Comment: 33 pages, 13 figures, accepted to the Astrophysical Journal February
4, 202
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Calibration of the Tip of the Red Giant Branch
The tip of the red giant branch (TRGB) method provides one of the most accurate and precise means of measuring the distances to nearby galaxies. Here we present a multi-wavelength, VIJHK absolute calibration of the TRGB based on observations of TRGB stars in the Large Magellanic Cloud (LMC), grounded on a geometric distance, determined by detached eclipsing binaries (DEBs). This paper presents a more detailed description of the method first presented by Freedman et al. for measuring corrections for the total line-of-sight extinction and reddening to the LMC. In this method, we use a differential comparison of the red giant population in the LMC, first with red giants in the Local Group galaxy IC 1613, and then with those in the Small Magellanic Cloud (SMC). As a consistency check, we derive an independent calibration of the TRGB sequence using the SMC alone, invoking its geometric distance also calibrated by DEBs. An additional consistency check comes from near-infrared observations of Galactic globular clusters covering a wide range of metallicities. In all cases we find excellent agreement in the zero-point calibration. We then examine the recent claims by Yuan et al., demonstrating that, in the case of the SMC, they corrected for extinction alone while neglecting the essential correction for reddening. In the case of IC 1613, we show that their analysis contains an incorrect treatment of (over-correction for) metallicity. Using our revised (and direct) measurement of the LMC TRGB extinction, we find a value of H0 = 69.6 ± 0.8 (±1.1% stat) ± 1.7 (±2.4% sys) km sâ1 Mpcâ1
Implementation of a Toffoli Gate with Superconducting Circuits
The quantum Toffoli gate allows universal reversible classical computation.
It is also an important primitive in many quantum circuits and quantum error
correction schemes. Here we demonstrate the realization of a Toffoli gate with
three superconducting transmon qubits coupled to a microwave resonator. By
exploiting the third energy level of the transmon qubit, the number of
elementary gates needed for the implementation of the Toffoli gate, as well as
the total gate time can be reduced significantly in comparison to theoretical
proposals using two-level systems only. We characterize the performance of the
gate by full process tomography and Monte Carlo process certification. The gate
fidelity is found to be %.Comment: 4 pages, 5figure
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