466 research outputs found
Scattering of coherent states on a single artificial atom
In this work we theoretically analyze a circuit QED design where propagating
quantum microwaves interact with a single artificial atom, a single Cooper pair
box. In particular, we derive a master equation in the so-called transmon
regime, including coherent drives. Inspired by recent experiments, we then
apply the master equation to describe the dynamics in both a two-level and a
three-level approximation of the atom. In the two-level case, we also discuss
how to measure photon antibunching in the reflected field and how it is
affected by finite temperature and finite detection bandwidth.Comment: 18 pages, 7 figure
A play of voices in marine conservation: Human experiences of fishery closures in Zanzibar
Based on stories written by Elizabeth (Liz) Drury O’Neill. These stories were directly taken from the research transcripts of OctoPINTS’ fieldwork in 2019. The stories were edited into a play by Tim Daw and Emilie Lindkvist. Kiswahili translation was made by Irene Musa and Andrew Wamukota. Layout and editing by Jineth BerrĂo-MarĂnez. Front page illustration by Krisztina JĂłnás.
In English AND Kiswahili.
This play script is an outcome of the OctoPINTS project https://octopints.wordpress.com/, a research project funded jointly by VR the Swedish Research Council, Sida the Swedish International Development Cooperation Agency, Formas the Swedish Research Council for Sustainable Development and Forte (Dnr 2018-05862). With additional support from the Stockholm Resilience Centre, the University of Dar es Salaam, and Pwani University. With huge thanks to Mwambao coastal community network, fieldwork hosts and collaborators
The role of plasma slowdown in the generation of Rhea's Alfven wings
Alfvén wings are known to form when a conducting or mass-loading object slows down a flowing plasma in its vicinity. Alfvén wings are not expected to be generated when an inert moon such as Rhea interacts with Saturn's magnetosphere, where the plasma impacting the moon is absorbed and the magnetic flux passes unimpeded through the moon. However, in two close polar passes of Rhea, Cassini clearly observed magnetic field signatures consistent with Alfvén wings. In addition, observations from a high-inclination flyby (Distance > 100 RRh) of Rhea on 3 June 2010 showed that the Alfvén wings continue to propagate away from Rhea even at this large distance. We have performed three-dimensional hybrid simulations of Rhea's interaction with Saturn's magnetosphere which show that the wake refilling process generates a plasma density gradient directed in the direction of corotating plasma. The resulting plasma pressure gradient exerts a force directed toward Rhea and slows down the plasma streaming into the wake along field lines. As on the same field lines, outside of the wake, the plasma continues to move close to its full speed, this differential motion of plasma bends the magnetic flux tubes, generating Alfvén wings in the wake. The current system excited by the Alfvén wings transfers momentum to the wake plasma extracting it from plasma outside the wake. Our work demonstrates that Alfvén wings can be excited even when a moon does not possess a conducting exosphere
Generation of nonclassical microwave states using an artificial atom in 1D open space
We have embedded an artificial atom, a superconducting transmon qubit, in a
1D open space and investigated the scattering properties of an incident
microwave coherent state. By studying the statistics of the reflected and
transmitted fields, we demonstrate that the scattered states can be
nonclassical. In particular, by measuring the second-order correlation
function, , we show photon antibunching in the reflected field and
superbunching in the transmitted field. We also compare the elastically and
inelastically scattered fields using both phase-sensitive and phase-insensitive
measurements.Comment: 5 pages, 3 figure
Three-Dimensional Modeling of Callisto's Surface Sputtered Exosphere Environment
We study the release of various elements from Callisto's surface into its
exosphere by plasma sputtering. The cold Jovian plasma is simulated with a 3D
plasma-planetary interaction hybrid model, which produces 2D surface
precipitation maps for magnetospheric H+ , O+ , O++ , and S++ . For the hot
Jovian plasma, we assume isotropic precipitation onto the complete spherical
surface. Two scenarios are investigated: One where no ionospheric shielding
takes place and accordingly full plasma penetration is implemented ('no
ionosphere' scenario), and one where an ionosphere lets virtually none of the
cold plasma but all of the hot plasma reach Callisto's surface ('ionosphere'
scenario). In the 3D exosphere model, neutral particles are sputtered from the
surface and followed on their individual trajectories. The 3D density profiles
show that whereas in the 'no ionosphere' scenario the ram direction is favored,
the 'ionosphere' scenario produces almost uniform density profiles. In
addition, the density profiles in the 'ionosphere' scenario are reduced by a
factor of ~2.5 with respect to the 'no ionosphere' scenario. We find that the
Neutral gas and Ion Mass spectrometer, which is part of the Particle
Environment Package on board the JUICE mission, will be able to detect the
different sputter populations from Callisto's icy surface and the major sputter
populations from Callisto's non-icy surface. The chemical composition of
Callisto's exosphere can be directly linked to the chemical composition of its
surface, and will offer us information not only on Callisto's formation
scenario but also on the building blocks of the Jupiter system.Comment: Published in JGR: Space Physic
Relativistic quantum clocks
The conflict between quantum theory and the theory of relativity is
exemplified in their treatment of time. We examine the ways in which their
conceptions differ, and describe a semiclassical clock model combining elements
of both theories. The results obtained with this clock model in flat spacetime
are reviewed, and the problem of generalizing the model to curved spacetime is
discussed, before briefly describing an experimental setup which could be used
to test of the model. Taking an operationalist view, where time is that which
is measured by a clock, we discuss the conclusions that can be drawn from these
results, and what clues they contain for a full quantum relativistic theory of
time.Comment: 12 pages, 4 figures. Invited contribution for the proceedings for
"Workshop on Time in Physics" Zurich 201
Reduction of the HIV-1 reservoir in resting CD4+ T-lymphocytes by high dosage intravenous immunoglobulin treatment: a proof-of-concept study
<p>Abstract</p> <p>Background</p> <p>The latency of HIV-1 in resting CD4<sup>+ </sup>T-lymphocytes constitutes a major obstacle for the eradication of virus in patients on antiretroviral therapy (ART). As yet, no approach to reduce this viral reservoir has proven effective.</p> <p>Methods</p> <p>Nine subjects on effective ART were included in the study and treated with high dosage intravenous immunoglobulin (IVIG) for five consecutive days. Seven of those had detectable levels of replication-competent virus in the latent reservoir and were thus possible to evaluate. Highly purified resting memory CD4<sup>+ </sup>T-cells were activated and cells containing replication-competent HIV-1 were quantified. HIV-1 from plasma and activated memory CD4<sup>+ </sup>T-cells were compared with single genome sequencing (SGS) of the <it>gag </it>region. T-lymphocyte activation markers and serum interleukins were measured.</p> <p>Results</p> <p>The latent HIV-1 pool decreased with in median 68% after IVIG was added to effective ART. The reservoir decreased in five, whereas no decrease was found in two subjects with detectable virus. Plasma HIV-1 RNA ≥ 2 copies/mL was detected in five of seven subjects at baseline, but in only one at follow-up after 8–12 weeks. The decrease of the latent HIV-1 pool and the residual plasma viremia was preceded by a transitory low-level increase in plasma HIV-1 RNA and serum interleukin 7 (IL-7) levels, and followed by an expansion of T regulatory cells. The magnitude of the viral increase in plasma correlated to the size of the latent HIV-1 pool and SGS of the <it>gag </it>region showed that viral clones from plasma clustered together with virus from activated memory T-cells, pointing to the latent reservoir as the source of HIV-1 RNA in plasma.</p> <p>Conclusion</p> <p>The findings from this uncontrolled proof-of-concept study suggest that the reservoir became accessible by IVIG treatment through activation of HIV-1 gene expression in latently-infected resting CD4<sup>+ </sup>T-cells. We propose that IVIG should be further evaluated as an adjuvant to effective ART.</p
Elucidating an amorphous form stabilization mechanism of tenapanor hydrochloride: crystal structure analysis using Xray diffraction, NMR crystallography and molecular modelling
By the combined use of powder and single crystal X-ray diffraction, solid-state NMR, and molecular modelling, the crystal structures of two systems containing the unusually large tenapanor drug molecule have been determined: the free form, ANHY and a dihydrochloride salt form, 2HCl. Dynamic nuclear polarization (DNP) assisted solid-state NMR (SSNMR) crystallography investigations were found essential for the final assignment, and were used to validate the crystal structure of ANHY. From the structural informatics analysis of ANHY and 2HCl, conformational ring differences in one part of the molecule were observed which influences the relative orientation of a methyl group on a ring nitrogen and thereby impacts the crystallizability of the dihydrochloride salt. From quantum chemistry calculations, the dynamics between different ring conformations in tenapanor is predicted to be fast. Addition of HCl to tenapanor results in general in a mixture of protonated ring conformers and hence a statistical mix of diastereoisomers which builds up the amorphous form, a-2HCl. This was qualitatively verified by 13C CP/MAS NMR investigations of the amorphous form. Thus, to form any significant amount of the crystalline material 2HCl, which originates from the minor (i.e., energetically less stable) ring conformations, one needs to involve nitrogen deprotonation to allow exchange between minor and major conformations of ANHY in solution. Thus, by controlling the solution pH value to well below the pKa of ANHY, the equilibrium between ANHY and 2HCl can be controlled and by this mechanism the crystallization of 2HCl can be avoided and the amorphous form of the dichloride salt can therefore be stabilized
PR3-ANCA:a promising biomarker in primary sclerosing cholangitis (PSC)
BACKGROUND AND AIMS:The only recognized biomarker for primary sclerosing cholangitis (PSC) is atypical anti-neutrophil cytoplasmic antibodies (aANCA), which, in addition to having low sensitivity and specificity, is an indirect immunofluorescence (IIF) test lacking the advantages of high throughput and objectivity. Recent reports have shown that antibodies to proteinase-3 (PR3-ANCA) might add diagnostic value in inflammatory bowel disease (IBD), specifically in ulcerative colitis (UC). As PSC is associated with IBD, the objective of this study was to evaluate the frequency and clinical significance of PR3-ANCA in a large cohort of patients. METHODS:A total of 244 PSC and 254 control [autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC), hepatitis C viral infection (HCV), hepatitis B viral infection (HBV), and healthy controls] sera and their clinical correlations were retrospectively analyzed for PR3-ANCA determined by ELISA and a new chemiluminescence immunoassay (CIA). Testing was also performed for aANCA by IIF. RESULTS:When measured by CIA, PR3-ANCA was detected in 38.5% (94/244) of PSC patients compared to 10.6% (27/254) controls (p<0.0001). By ELISA, PR3-ANCA was detected in 23.4% (57/244) of PSC patients compared to 2.7% (6/254) controls (p<0.0001). PR3-ANCA in PSC patients was not associated with the presence or type of underlying IBD, and, in fact, it was more frequent in Crohn's disease (CD) patients with PSC than previously reported in CD alone. PR3-ANCA in PSC measured by CIA correlated with higher liver enzymes. CONCLUSION:PR3-ANCA is detected in a significant proportion of PSC patients compared to other liver diseases including PBC and AIH. PR3-ANCA is associated with higher liver enzyme levels in PSC, and is not solely related to underlying IBD
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