202 research outputs found
The objective assessment of sleep in cluster headache: State of the art and future directions
: Several lines of evidence suggest that cluster headache is related to chronobiology and sleep. Nevertheless, the nature of such a relationship is unclear. In this view, the objective evaluation of sleep in cluster headache has strong theoretical and clinical relevance. Here, we provide an in-depth narrative review of the literature on objective sleep assessment in cluster headache. We found that only a small number of studies (N = 12) focused on this topic. The key research aims were directed to assess: (a) the relationship between cluster headache and sleep breathing disorders; (b) the temporal relationship between sleep stages/events and cluster headache attacks; (c) sleep macrostructure in patients with cluster headache. No studies considered sleep microstructure. The reviewed studies are heterogeneous, conducted by a few research groups, and often characterised by relevant methodological flaws. Results are substantially inconclusive considering the main hypothesis. We outline several methodological points that should be considered for future research, and suggest that evaluating sleep microstructure, local sleep electrophysiology and actigraphic measures may strongly increase knowledge on the relationship between sleep and cluster headache
Pseudogap and superconductivity in two-dimensional doped charge-transfer insulators
High-temperature superconductivity emerges in the CuO plane upon doping a
Mott insulator. To ascertain the influence of Mott physics plus short-range
correlations, we solve a three-band copper-oxide model in the charge-transfer
regime using cellular dynamical mean-field theory with continuous-time quantum
Monte Carlo as an impurity solver. We report the normal and superconducting
phase diagram of this model as a function of doping, interaction strength and
temperature. Upon hole doping of the charge-transfer insulator, the phase
boundary between pseudogap and correlated metal consists of a first-order
transition line at finite doping ending at a critical point, as in the one-band
model. Beyond the endpoint, the phase boundary continues as a Widom crossover
line, across which thermodynamic quantities peak. This phase boundary
determines changes in the pairing mechanism and is an emergent phenomenon
characteristic of doped Mott insulators, independent of many microscopic
details. Broader implications are discussed.Comment: 6 pages, 4 figures and supplementary information; published versio
Effects of interaction strength, doping, and frustration on the antiferromagnetic phase of the two-dimensional Hubbard model
Recent quantum-gas microscopy of ultracold atoms and scanning tunneling
microscopy of the cuprates reveal new detailed information about doped Mott
antiferromagnets, which can be compared with calculations. Using cellular
dynamical mean-field theory, we map out the antiferromagnetic (AF) phase of the
two-dimensional Hubbard model as a function of interaction strength , hole
doping and temperature . The N\'eel phase boundary is non-monotonic
as a function of and . Frustration induced by second-neighbor
hopping reduces N\'eel order more effectively at small . The doped AF is
stabilized at large by kinetic energy and at small by potential energy.
The transition between the AF insulator and the doped metallic AF is
continuous. At large , we find in-gap states similar to those observed in
scanning tunneling microscopy. We predict that, contrary to the Hubbard bands,
these states are only slightly spin polarized.Comment: 6 pages, 3 figures and supplemental informatio
Signatures of the Mott transition in the antiferromagnetic state of the two-dimensional Hubbard model
The properties of a phase with large correlation length can be strongly
influenced by the underlying normal phase. We illustrate this by studying the
half-filled two-dimensional Hubbard model using cellular dynamical mean-field
theory with continuous-time quantum Monte Carlo. Sharp crossovers in the
mechanism that favors antiferromagnetic correlations and in the corresponding
local density of states are observed. These crossovers occur at values of the
interaction strength and temperature that are controlled by the
underlying normal-state Mott transition.Comment: 5 pages, 3 figures and 4 appendices; published versio
Intermittent docetaxel chemotherapy as first-line treatment for metastatic castration-resistant prostate cancer patients
Aims: The intermittent administration of chemotherapy is a means of preserving patients' quality of life (QL). The aim of this study was to verify whether the intermittent administration of docetaxel (DOC) improves the patients' QL. Patients & methods: All patients received DOC 70 mg/m every 3 weeks for eight cycles. The patients were randomized to receive DOC continuously or with a fixed 3-month interval after the first four DOC courses. Results: The study involved 148 patients. There was no difference in QL between the groups receiving intermittent or continuous treatment. Intermittence had no detrimental effects on disease control. Conclusion: Although feasible and not detrimental, our results showed that true intermittent chemotherapy in metastatic castration-resistant prostate cancer patients failed to improve the patients' QL
Antagonistic effects of nearest-neighbor repulsion on the superconducting pairing dynamics in the doped Mott insulator regime
The nearest-neighbor superexchange-mediated mechanism for d_{x^2-y^2}-wave
superconductivity in the one-band Hubbard model faces the challenge that
nearest-neighbor Coulomb repulsion can be larger than superexchange. To answer
this question, we use cellular dynamical mean-field theory (CDMFT) with a
continuous-time quantum Monte Carlo solver to determine the superconducting
phase diagram as a function of temperature and doping for on-site repulsion
and nearest-neighbor repulsion . In the underdoped regime,
increases the CDMFT superconducting transition temperature even
though it decreases the superconducting order parameter at low temperature for
all dopings. However, decreases in the overdoped regime. We gain
insight into these paradoxical results through a detailed study of the
frequency dependence of the anomalous spectral function, extracted at finite
temperature via the MaxEntAux method for analytic continuation. A systematic
study of dynamical positive and negative contributions to pairing reveals that
even though has a high-frequency depairing contribution, it also has a low
frequency pairing contribution since it can reinforce superexchange through
. Retardation is thus crucial to understand pairing in doped Mott
insulators, as suggested by previous zero-temperature studies. We also comment
on the tendency to charge order for large and on the persistence of d-wave
superconductivity over extended- or s+d-wave.Comment: Latex, 16 pages, 8 figure
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