12,293 research outputs found
Complete sets of cyclic mutually unbiased bases in even prime power dimensions
We present a construction method for complete sets of cyclic mutually
unbiased bases (MUBs) in Hilbert spaces of even prime power dimensions. In
comparison to usual complete sets of MUBs, complete cyclic sets possess the
additional property of being generated by a single unitary operator. The
construction method is based on the idea of obtaining a partition of
multi-qubit Pauli operators into maximal commuting sets of orthogonal operators
with the help of a suitable element of the Clifford group. As a consequence, we
explicitly obtain complete sets of cyclic MUBs generated by a single element of
the Clifford group in dimensions for .Comment: 10 page
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Cryo-EM structure of the potassium-chloride cotransporter KCC4 in lipid nanodiscs.
Cation-chloride-cotransporters (CCCs) catalyze transport of Cl- with K+ and/or Na+across cellular membranes. CCCs play roles in cellular volume regulation, neural development and function, audition, regulation of blood pressure, and renal function. CCCs are targets of clinically important drugs including loop diuretics and their disruption has been implicated in pathophysiology including epilepsy, hearing loss, and the genetic disorders Andermann, Gitelman, and Bartter syndromes. Here we present the structure of a CCC, the Mus musculus K+-Cl- cotransporter (KCC) KCC4, in lipid nanodiscs determined by cryo-EM. The structure, captured in an inside-open conformation, reveals the architecture of KCCs including an extracellular domain poised to regulate transport activity through an outer gate. We identify binding sites for substrate K+ and Cl- ions, demonstrate the importance of key coordinating residues for transporter activity, and provide a structural explanation for varied substrate specificity and ion transport ratio among CCCs. These results provide mechanistic insight into the function and regulation of a physiologically important transporter family
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Emotional Performance and Antiracism in the Writing Center
Why do conversations regarding students’ right to their own
language and antiracism in the writing center still invite insults and
agitation? After all, these struggles for students’ rights to selfdetermination
and their own language in composition are far from
new. The narratives present within this writing move beyond mere
analysis of how and why established institutions attempt to
control, and, rather, put Laura Micciche’s theories of emotion and
performance to the test. When teaching tutor training, readings
regarding students' right to their own language and race potentially
cause conflict and can, at least at first, elicit strong emotional
responses. This article explores the value of such early emotional
reactions to these readings. Can the tutors’ emotional
performances, both in action and voice, eventually help to bring
attention to, or subvert the backlash and attacks antiracism
rhetoric tends to invite? Within its pages, Micciche’s Doing Emotion:
Rhetoric, Writing, Teaching suggests that we perform emotional
appeals rather than simply make them. Through performance, she
claims, we present emotion, not as something that resides in
people to be shared or withheld, but as encounters between
people. This article’s narrative “reenactments,” then, are set to
reveal the fears and desires behind the resistance I’ve both
witnessed and encountered all while promoting what I deem to be
a necessity for emotional performance in antiracism and writing
center work.University Writing Cente
Numerical and semi-analytic core mass distributions in supersonic isothermal turbulence
We investigate the influence of the turbulence forcing on the mass
distributions of gravitationally unstable cores by postprocessing data from
simulations of non-selfgravitating isothermal supersonic turbulence with
varying resolution. In one set of simulations solenoidal forcing is applied,
while the second set uses purely compressive forcing to excite turbulent
motions. From the resulting density field, we compute the mass distribution of
gravitationally unstable cores by means of a clump-finding algorithm. Using the
time-averaged probability density functions of the mass density, semi-analytic
mass distributions are calculated from analytical theories. We apply stability
criteria that are based on the Bonnor-Ebert mass resulting from the thermal
pressure and from the sum of thermal and turbulent pressure. Although there are
uncertainties in the application of the clump-finding algorithm, we find
systematic differences in the mass distributions obtained from solenoidal and
compressive forcing. Compressive forcing produces a shallower slope in the
high-mass power-law regime compared to solenoidal forcing. The mass
distributions also depend on the Jeans length resulting from the choice of the
mass in the computational box, which is freely scalable for non-selfgravitating
isothermal turbulence. Provided that all cores are numerically resolved and
most cores are small compared to the length scale of the forcing, the
normalised core mass distributions are found to be close to the semi-analytic
models. Especially for the high-mass tails, the Hennebelle-Chabrier theory
implies that the additional support due to turbulent pressure is important.Comment: 15 pages, 7 figures, submitted to A&
Contributions of Inflammatory Processes to the Development of the Early Stages of Diabetic Retinopathy
Diabetes causes metabolic and physiologic abnormalities in the retina, and these changes suggest a role for inflammation in the development of diabetic retinopathy. These changes include upregulation of iNOS, COX-2, ICAM-1, caspase 1, VEGF, and NF-κB, increased production of nitric oxide, prostaglandin E2, IL-1β, and cytokines, as well as increased permeability and leukostasis. Using selective pharmacologic inhibitors or genetically modified animals, an increasing number of therapeutic approaches have been identified that significantly inhibit development of at least the early stages of diabetic retinopathy, especially occlusion and degeneration of retinal capillaries. A common feature of a number of these therapies is that they inhibit production of inflammatory mediators. The concept that localized inflammatory processes play a role in the development of diabetic retinopathy is relatively new, but evidence that supports the hypothesis is accumulating rapidly. This new hypothesis offers new insight into the pathogenesis of diabetic retinopathy, and offers novel targets to inhibit the ocular disease
Emulating Simulations of Cosmic Dawn for 21cm Power Spectrum Constraints on Cosmology, Reionization, and X-ray Heating
Current and upcoming radio interferometric experiments are aiming to make a
statistical characterization of the high-redshift 21cm fluctuation signal
spanning the hydrogen reionization and X-ray heating epochs of the universe.
However, connecting 21cm statistics to underlying physical parameters is
complicated by the theoretical challenge of modeling the relevant physics at
computational speeds quick enough to enable exploration of the high dimensional
and weakly constrained parameter space. In this work, we use machine learning
algorithms to build a fast emulator that mimics expensive simulations of the
21cm signal across a wide parameter space to high precision. We embed our
emulator within a Markov-Chain Monte Carlo framework, enabling it to explore
the posterior distribution over a large number of model parameters, including
those that govern the Epoch of Reionization, the Epoch of X-ray Heating, and
cosmology. As a worked example, we use our emulator to present an updated
parameter constraint forecast for the Hydrogen Epoch of Reionization Array
experiment, showing that its characterization of a fiducial 21cm power spectrum
will considerably narrow the allowed parameter space of reionization and
heating parameters, and could help strengthen Planck's constraints on
. We provide both our generalized emulator code and its
implementation specifically for 21cm parameter constraints as publicly
available software.Comment: 22 pages, 9 figures; accepted to Ap
The Economics of Sports
The contributors to this book, all economists at the forefront of the movement to study the economics of sports, show how a host of contemporary economic issues come into play in today\u27s world of sports. These issues include industrial organization, influences on labor markets, monopsony power, the behavior of cartels, local economic development policies, and price discrimination.https://research.upjohn.org/up_press/1188/thumbnail.jp
Short-lived Radio Bursts from the Crab Pulsar
Our high-time-resolution observations reveal that individual main pulses from
the Crab pulsar contain one or more short-lived microbursts. Both the energy
and duration of bursts measured above 1 GHz can vary dramatically in less than
a millisecond. These fluctuations are too rapid to be caused by propagation
through turbulence in the Crab Nebula or the interstellar medium; they must be
intrinsic to the radio emission process in the pulsar. The mean duration of a
burst varies with frequency as , significantly different from the
broadening caused by interstellar scattering. We compare the properties of the
bursts to some simple models of microstructure in the radio emission region.Comment: 34 pages, 10 figures; accepted for publication in Ap
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