1,118 research outputs found
Far-off-equilibrium expansion trajectories in the QCD phase diagram
We consider the hydrodynamic evolution of a quark-gluon gas with non-zero
quark masses and net baryon number in its phase diagram. For
far-off-equilibrium initial conditions the expansion trajectories appear to
violate simple rules based on the second law of thermodynamics that were
previously established for ideal or weakly dissipative fluids. For Bjorken flow
we present a detailed analysis within kinetic theory that provides a full
microscopic understanding of these macroscopic phenomena and establishes their
thermodynamic consistency. We point out that, for certain far-off-equilibrium
initial conditions, the well-known phenomenon of "viscous heating" turns into
"viscous cooling" where, driven by dissipative effects, the temperature
decreases faster than in adiabatic expansion.Comment: 25 pages, 14 figures (manuscript now in PRC format, added references
Far-off-equilibrium early-stage dynamics in high-energy nuclear collisions
We explore the far-off-equilibrium aspects of the (1+1)-dimensional
early-stage evolution of a weakly-coupled quark-gluon plasma using kinetic
theory and hydrodynamics. For a large set of far-off-equilibrium initial
conditions the system exhibits a peculiar phenomenon where its total
equilibrium entropy decreases with time. Using a non-equilibrium definition of
entropy based on Boltzmann's H-function, we demonstrate how this apparently
anomalous behavior is consistent with the second law of thermodynamics. We also
use the H-function to formulate `maximum-entropy' hydrodynamics, a
far-off-equilibrium macroscopic theory that can describe both free-streaming
and near-equilibrium regimes of quark-gluon plasma in a single framework.Comment: Contribution to Quark Matter 2023 (4 pages, 4 figures
Fluid dynamics from the Boltzmann equation using a maximum entropy distribution
Using the recently developed ``Maximum Entropy'' (or ``least biased'')
distribution function to truncate the moment hierarchy arising from kinetic
theory, we formulate a far-from-equilibrium macroscopic theory that provides
the possibility of describing both free-streaming and hydrodynamic regimes of
heavy-ion collisions within a single framework. Unlike traditional hydrodynamic
theories that include viscous corrections to finite order, the present
formulation incorporates contributions to all orders in shear and bulk inverse
Reynolds numbers, allowing it to handle large dissipative fluxes. By
considering flow profiles relevant for heavy-ion collisions (Bjorken and Gubser
flows), we demonstrate that the present approach provides excellent agreement
with underlying kinetic theory throughout the fluid's evolution and,
especially, in far-off-equilibrium regimes where traditional hydrodynamics
breaks down.Comment: 29 pages, 19 figure
Comparison of the Low-Cost Sun Sensors of the SOURCE and EIVE CubeSats
Sun sensors are commonly used attitude determination equipment which measure a spacecraft’s attitude relative to the sun. Multiple types of low-cost sun sensors were developed for the SOURCE and EIVE CubeSats. The SOURCE sun sensors consist of single photodiodes which are placed in a one-sensor-per-face as well as a pyramid arrangement. EIVE employs digital vector sun sensors based on quad-pin photodiodes. The SOURCE sun sensors in the one-sensor-per-face arrangement archive an accuracy of \u3c10° while the pyramid arrangement accomplishes an accuracy of \u3c7.5° without and \u3c5° with calibration. EIVE’s vector sun sensors offer an raw accuracy of 3°±5°. Multiple calibration approaches are presented with the best results leading to an accuracy of 0.7±3°. A direct comparison between the SOURCE and EIVE sensor types and configurations can be drawn since the same test bench was used to measure all sensors. The objective of this paper is to present and compare the different sun sensor concepts and their results
D=2 gluon condensate and QCD propagators at finite temperature
We calculate the dimension two gluon condensate contribution to quark, gluon
and ghost propagators at finite temperature.Comment: Minor modifications. Accepted in PL
Spin systems with dimerized ground states
In view of the numerous examples in the literature it is attempted to outline
a theory of Heisenberg spin systems possessing dimerized ground states (``DGS
systems") which comprises all known examples. Whereas classical DGS systems can
be completely characterized, it was only possible to provide necessary or
sufficient conditions for the quantum case. First, for all DGS systems the
interaction between the dimers must be balanced in a certain sense. Moreover,
one can identify four special classes of DGS systems: (i) Uniform pyramids,
(ii) systems close to isolated dimer systems, (iii) classical DGS systems, and
(iv), in the case of , systems of two dimers satisfying four
inequalities. Geometrically, the set of all DGS systems may be visualized as a
convex cone in the linear space of all exchange constants. Hence one can
generate new examples of DGS systems by positive linear combinations of
examples from the above four classes.Comment: With corrections of proposition 4 and other minor change
Erratum to: ‘Early prediction of acute kidney injury after transapical and transaortic aortic valve implantation with urinary G1 cell cycle arrest biomarkers’
Background: Acute kidney injury (AKI) is a common complication following transcatheter aortic valve implantation (TAVI) leading to increased mortality and morbidity. Urinary G1 cell cycle arrest proteins TIMP-2 and IGFBP7 have recently been suggested as sensitive biomarkers for early detection of AKI in critically ill patients. However, the precise role of urinary TIMP-2 and IGFBP7 in patients undergoing TAVI is unknown. Methods: In a prospective observational trial, 40 patients undergoing TAVI (either transaortic or transapical) were enrolled. Serial measurements of TIMP-2 and IGFBP7 were performed in the early post interventional course. The primary clinical endpoint was the occurrence of AKI stage 2/3 according to the KDIGO classification. Results: Now we show, that ROC analyses of [TIMP-2]*[IGFBP7] on day one after TAVI reveals a sensitivity of 100 % and a specificity of 90 % for predicting AKI 2/3 (AUC 0.971, 95 % CI 0.914-1.0, SE 0.0299, p = 0.001, cut-off 1.03). In contrast, preoperative and postoperative serum creatinine levels as well as glomerular filtration rate (GFR) and perioperative change in GFR did not show any association with the development of AKI. Furthermore, [TIMP2]*[IGFBP7] remained stable in patients with AKI = 1, but its levels increased significantly as early as 24 h after TAVI in patients who developed AKI 2/3 in the further course (4.77 +/- 3.21 vs. 0.48 +/- 0.68, p = 0.022). Mean patients age was 81.2 +/- 5.6 years, 16 patients were male (40.0 %). 35 patients underwent transapical and five patients transaortic TAVI. 15 patients (37.5 %) developed any kind of AKI;eight patients (20 %) met the primary endpoint and seven patients required renal replacement therapy (RRT) within 72 h after surgery. Conclusion: Early elevation of urinary cell cycle arrest biomarkers after TAVI is associated with the development of postoperative AKI. [TIMP-2]*[ IGFBP7] provides an excellent diagnostic accuracy in the prediction of AKI that is superior to that of serum creatinine
Non-perturbative thermal flows and resummations
We construct a functional renormalisation group for thermal fluctuations.
Thermal resummations are naturally built in, and the infrared problem of
thermal fluctuations is well under control. The viability of the approach is
exemplified for thermal scalar field theories. In gauge theories the present
setting allows for the construction of a gauge-invariant thermal
renormalisation group.Comment: 16 pages, eq (38) added to match published versio
Hadron Production in Ultra-relativistic Nuclear Collisions: Quarkyonic Matter and a Triple Point in the Phase Diagram of QCD
We argue that features of hadron production in relativistic nuclear
collisions, mainly at CERN-SPS energies, may be explained by the existence of
three forms of matter: Hadronic Matter, Quarkyonic Matter, and a Quark-Gluon
Plasma. We suggest that these meet at a triple point in the QCD phase diagram.
Some of the features explained, both qualitatively and semi-quantitatively,
include the curve for the decoupling of chemical equilibrium, along with the
non-monotonic behavior of strange particle multiplicity ratios at center of
mass energies near 10 GeV. If the transition(s) between the three phases are
merely crossover(s), the triple point is only approximate.Comment: 28 pages, 9 figures; submitted to Nucl. Phys. A; v2 to eliminate
obsolete figs. inadvertently attached at the end of the paper; v3: final
version accepted for publicatio
Self-associated molecular patterns mediate cancer immune evasion by engaging Siglecs on T cells
© 2018, American Society for Clinical Investigation. This article has been published in final form at https://doi.org/10.1172/JCI120612First-generation immune checkpoint inhibitors, including anti-CTLA-4 and anti-programmed death 1 (anti-PD-1) antibodies, have led to major clinical progress, yet resistance frequently leads to treatment failure. Thus, new targets acting on T cells are needed. CD33-related sialic acid-binding immunoglobulin-like lectins (Siglecs) are pattern-recognition immune receptors binding to a range of sialoglycan ligands, which appear to function as self-associated molecular patterns (SAMPs) that suppress autoimmune responses. Siglecs are expressed at very low levels on normal T cells, and these receptors were not until recently considered as interesting targets on T cells for cancer immunotherapy. Here, we show an upregulation of Siglecs, including Siglec-9, on tumor-infiltrating T cells from non-small cell lung cancer (NSCLC), colorectal, and ovarian cancer patients. Siglec-9-expressing T cells coexpressed several inhibitory receptors, including PD-1. Targeting of the sialoglycan-SAMP/Siglec pathway in vitro and in vivo resulted in increased anticancer immunity. T cell expression of Siglec-9 in NSCLC patients correlated with reduced survival, and Siglec-9 polymorphisms showed association with the risk of developing lung and colorectal cancer. Our data identify the sialoglycan-SAMP/Siglec pathway as a potential target for improving T cell activation for immunotherapy.Peer reviewe
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