1,442 research outputs found
Universality in Three- and Four-Body Bound States of Ultracold Atoms
Under certain circumstances, three or more interacting particles may form
bound states. While the general few-body problem is not analytically solvable,
the so-called Efimov trimers appear for a system of three particles with
resonant two-body interactions. The binding energies of these trimers are
predicted to be universally connected to each other, independent of the
microscopic details of the interaction. By exploiting a Feshbach resonance to
widely tune the interactions between trapped ultracold lithium atoms, we find
evidence for two universally connected Efimov trimers and their associated
four-body bound states. A total of eleven precisely determined three- and
four-body features are found in the inelastic loss spectrum. Their relative
locations on either side of the resonance agree well with universal theory,
while a systematic deviation from universality is found when comparing features
across the resonance.Comment: 16 pages including figures and Supplementary Online Materia
Spectrum of the Frobenius-Perron operator for systems with stochastic perturbation
We analyze the problem of evolution in a system with stochastic perturbation
and point out that analytic properties of the noise present in the system might
determine spectral properties of the evolution operator (Frobenius-Perron
operator). We also propose a method for approximation of the spectrum and
eigenvectors of the FP-operator by applying a suitable noise. Moreover we
demonstrate that the eigenvalues of the FP-operator located outside the
essential spectrum are robust not only against local perturbation but also
against the non local perturbation and that these stable eigenvalues have a
direct physical meaning: they determine the rate of the exponential decay of
correlation in the system.Comment: LaTeX2e, 11 pages, 6 figures (EPS format
Pseudogap and charge density waves in two dimensions
An interaction between electrons and lattice vibrations (phonons) results in
two fundamental quantum phenomena in solids: in three dimensions it can turn a
metal into a superconductor whereas in one dimension it can turn a metal into
an insulator. In two dimensions (2D) both superconductivity and charge-density
waves (CDW) are believed to be anomalous. In superconducting cuprates, critical
transition temperatures are unusually high and the energy gap may stay unclosed
even above these temperatures (pseudogap). In CDW-bearing dichalcogenides the
resistivity below the transition can decrease with temperature even faster than
in the normal phase and a basic prerequisite for the CDW, the favourable
nesting conditions (when some sections of the Fermi surface appear shifted by
the same vector), seems to be absent. Notwithstanding the existence of
alternatives to conventional theories, both phenomena in 2D still remain the
most fascinating puzzles in condensed matter physics. Using the latest
developments in high-resolution angle-resolved photoemission spectroscopy
(ARPES) here we show that the normal-state pseudogap also exists in one of the
most studied 2D examples, dichalcogenide 2H-TaSe2, and the formation of CDW is
driven by a conventional nesting instability, which is masked by the pseudogap.
Our findings reconcile and explain a number of unusual, as previously believed,
experimental responses as well as disprove many alternative theoretical
approaches. The magnitude, character and anisotropy of the 2D-CDW pseudogap are
intriguingly similar to those seen in superconducting cuprates.Comment: 14 pages including figures and supplementary informatio
Adaptation to the Edge of Chaos in the Self-Adjusting Logistic Map
Self-adjusting, or adaptive systems have gathered much recent interest. We
present a model for self-adjusting systems which treats the control parameters
of the system as slowly varying, rather than constant. The dynamics of these
parameters is governed by a low-pass filtered feedback from the dynamical
variables of the system. We apply this model to the logistic map and examine
the behavior of the control parameter. We find that the parameter leaves the
chaotic regime. We observe a high probability of finding the parameter at the
boundary between periodicity and chaos. We therefore find that this system
exhibits adaptation to the edge of chaos.Comment: 3 figure
Crizotinib: aseptic abscesses in multiple organs during treatment of EML4-ALK-positive NSCLC
Purpose We report a novel side efect of Crizotinib, an oral ALK inhibitor used in the treatment of non-small cell lung
cancer (NSCLC) with activating rearrangement of EML4-ALK. It expands the known spectrum of complications of
Crizotinib.
Methods Clinical case report.
Results Multiple aseptic and recurrent abscesses were observed in the liver, thoracic wall as well as in both kidneys
in a 75-year-old female patient sufering from NSCLC who had been treated with Crizotinib for almost 2 years. After
discontinuation of the treatment the abscesses dissolved spontaneously and did not reoccur.
Conclusion Aseptic abscesses under treatment with Crizotinib are not restricted to the kidneys as described before, but
can also occur in other abdominal organs as the liver and even in the thoracic wall. We postulate that this fnding may
point to a yet unknown not tissue-dependent mechanism of actio
Merit, Tenure, and Bureaucratic Behavior: Evidence From a Conjoint Experiment in the Dominican Republic
Bureaucratic behavior in developing countries remains poorly understood. Why do some
public servants â yet not others â work hard to deliver public services, misuse state
resources, and/or participate in electoral mobilization? A classic answer comes from Weber:
bureaucratic structures shift behavior towards integrity, neutrality, and commitment to
public service. Our paper conducts the first survey experimental test of the effects of
bureaucratic structures. It does so through a conjoint experiment with public servants in the
Dominican Republic. Looking at merit examinations and job stability, we find that Weber
was right â but only partially. Recruitment by examination curbs corruption and political
services by bureaucrats, while enhancing work motivation. Job stability, by contrast, only
decreases political services: tenured bureaucrats are less likely to participate in electoral
mobilization. Examinations thus enhance the quality of bureaucracy (motivation and lower
corruption) and democracy (electoral competition); job stability only enhances the quality
of democracy
Simultaneous MMC readout using a tailored {\mu}MUX based readout system
Magnetic microcalorimeters (MMCs) are cryogenic, energy-dispersive
single-particle detectors providing excellent energy resolution, intrinsically
fast signal rise time, quantum efficiency close to 100\%, large dynamic range
as well as almost ideal linear response. One of the remaining challenges to be
overcome to ultimately allow for the utilization of large-scale MMC based
detector arrays with thousands to millions of individual pixels is the
realization of a SQUID based multiplexing technique particularly tailored for
MMC readout. Within this context, we report on the first truly multiplexed
readout of an MMC based detector array using a frequency-division multiplexing
approach realized by a custom microwave SQUID multiplexer based readout system.Comment: Conference: ASC2022 (accepted for publication in IEEE Transactions on
Applied Superconductivity
Myosin-5, kinesin-1 and myosin-17 cooperate in secretion of fungal chitin synthase
The interactions between cytoskeletal motors are here explored in the context of polarized secretion in fungi, revealing unexpected complexity in the regulation of vesicle transport to and docking at the hyphal tip
Mutations in the gdpP gene are a clinically relevant mechanism for ÎČ-lactam resistance in meticillin-resistant Staphylococcus aureus lacking mec determinants
In Staphylococcus aureus, resistance to ÎČ-lactamase stable ÎČ-lactam antibiotics is mediated by the penicillinbinding protein 2a, encoded by mecA or by its homologues mecB or mecC. However, a substantial number of meticillin-resistant isolates lack known mec genes and, thus, are called meticillin resistant lacking mec (MRLM). This study aims to identify the genetic mechanisms underlying the MRLM phenotype. A total of 141 MRLM isolates and 142 meticillin-susceptible controls were included in this study. Oxacillin and cefoxitin minimum inhibitory concentrations were determined by broth microdilution and the presence of mec genes was excluded by PCR. Comparative genomics and a genome-wide association study (GWAS) approach were applied to identify genetic polymorphisms associated with the MRLM phenotype. The potential impact of such mutations on the expression of PBP4, as well as on cell morphology and biofilm formation, was investigated. GWAS revealed that mutations in gdpP were significantly associated with the MRLM phenotype. GdpP is a phosphodiesterase enzyme involved in the degradation of the second messenger cyclic-di-AMP in S. aureus. A total of 131 MRLM isolates carried truncations, insertions or deletions as well as amino acid substitutions, mainly located in the functional DHH-domain of GdpP. We experimentally verified the contribution of these gdpP mutations to the MRLM phenotype by heterologous complementation experiments. The mutations in gdpP had no effect on transcription levels of pbp4; however, cell sizes of MRLM strains were reduced. The impact on biofilm formation was highly strain dependent. We report mutations in gdpP as a clinically relevant mechanism for ÎČ-lactam resistance in MRLM isolates. This observation is of particular clinical relevance, since MRLM are easily misclassified as MSSA (meticillin-susceptible S. aureus), which may lead to unnoticed spread of ÎČ-lactam-resistant isolates and subsequent treatment failure.Peer Reviewe
Time-dependent Ginzburg-Landau Equation in the Nambu--Jona-Lasinio Model
We apply the closed time-path Green function formalism in the
Nambu--Jona-Lasinio model. First of all, we use this formalism to obtain the
well-known gap equation for the quark condensate in a stationary homogeneous
system. We have also used this formalism to obtain the Ginzburg-Landau (GL)
equation and the time-dependent Ginzburg-Landau (TDGL) equation for the chiral
order parameter in an inhomogeneous system. In our derived GL and TDGL
equations, there is no other parameters except for those in the original NJL
model.Comment: 20 pages, no figures. Version to appear in Nuclear Physics
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