25 research outputs found
Loschmidt Echo of Far-From-Equilibrium Fermionic Superfluids
Non-analyticities in the logarithm of the Loschmidt echo, known as dynamical
quantum phase transitions [DQPTs], are a recently introduced attempt to
classify the myriad of possible phenomena which can occur in far from
equilibrium closed quantum systems. In this work, we analytically investigate
the Loschmidt echo in nonequilibrium -wave and topological
fermionic superfluids. We find that the presence of non-analyticities in the
echo is not invariant under global rotations of the superfluid phase. We remedy
this deficiency by introducing a more general notion of a grand canonical
Loschmidt echo. Overall, our study shows that DQPTs are not a good indicator
for the long time dynamics of an interacting system. In particular, there are
no DQPTs to tell apart distinct dynamical phases of quenched BCS
superconductors. Nevertheless, they can signal a quench induced change in the
topology and also keep track of solitons emerging from unstable stationary
states of a BCS superconductor.Comment: 24 pages, 12 figure
A bioprinted 3D gut model with crypt-villus structures to mimic the intestinal epithelial-stromal microenvironment
The intestine is a complex tissue with a characteristic three-dimensional (3D) crypt-villus architecture, which plays a key role in the intestinal function. This function is also regulated by the intestinal stroma that actively supports the intestinal epithelium, maintaining the homeostasis of the tissue. Efforts to account for the 3D complex structure of the intestinal tissue have been focused mainly in mimicking the epithelial barrier, while solutions to include the stromal compartment are scarce and unpractical to be used in routine experiments. Here we demonstrate that by employing an optimized bioink formulation and the suitable printing parameters it is possible to produce fibroblast-laden crypt-villus structures by means of digital light projection stereolithography (DLP-SLA). This process provides excellent cell viability, accurate spatial resolution, and high printing throughput, resulting in a robust biofabrication approach that yields functional gut mucosa tissues compatible with conventional testing techniques.Copyright © 2023 Elsevier B.V. All rights reserved
Nonlocality as the source of purely quantum dynamics of BCS superconductors
We show that the classical (mean-field) description of far from equilibrium
superconductivity is exact in the thermodynamic limit for local observables but
breaks down for global quantities, such as the entanglement entropy or
Loschmidt echo. We do this by solving for and comparing exact quantum and exact
classical long-time dynamics of a BCS superconductor with interaction strength
inversely proportional to time and evaluating local observables explicitly.
Mean field is exact for both normal and anomalous averages (superconducting
order) in the thermodynamic limit. However, for anomalous expectation values,
this limit does not commute with adiabatic and strong coupling limits and, as a
consequence, their quantum fluctuations can be unusually strong. The long-time
steady state of the system is a gapless superconductor whose superfluid
properties are only accessible through energy resolved measurements. This state
is nonthermal but conforms to an emergent generalized Gibbs ensemble. Our study
clarifies the nature of symmetry-broken many-body states in and out of
equilibrium and fills a crucial gap in the theory of time-dependent quantum
integrability.Comment: 30 pages, 10 figures, new titl
Measurement induced criticality in quasiperiodic modulated random hybrid circuits
We study one-dimensional hybrid quantum circuits perturbed by quenched
quasiperiodic (QP) modulations across the measurement-induced phase transition
(MIPT). Considering non-Pisot QP structures, characterized by unbounded
fluctuations, allows us to tune the wandering exponent to exceed the
Luck bound for the stability of the MIPT where . Via large-scale numerical simulations of random Clifford circuits
interleaved with local projective measurements, we find that sufficiently large
QP structural fluctuations destabilize the MIPT and induce a flow to a broad
family of critical dynamical phase transitions of the infinite QP type that is
governed by the wandering exponent, . We numerically determine the
associated critical properties, including the correlation length exponent
consistent with saturating the Luck bound, and a universal activated dynamical
scaling with activation exponent , finding excellent
agreement with the conclusions of real space renormalization group
calculations.Comment: 14 pages, 13 figure
Prevalencia de hipotensión ortostática en ancianos hipertensos tratados en atención primaria
ObjetivoConocer la prevalencia de hipotensión ortostática (HO) y los factores asociados en ancianos hipertensos tratados en atención primaria (AP).DiseñoEstudio descriptivo, transversal.EmplazamientoCentro de Salud La Marina (centro urbano en Santander).PacientesUna muestra aleatoria de 295 pacientes de 65 o más años atendidos regularmente por presentar hipertensión arterial (HTA).Mediciones y resultados principalesSe han obtenido cifras de presión arterial (PA) en sedestación y en bipedestación. La definición de HO utilizada ha sido: disminución de 20 mmHg o más en la PA sistólica (PAS) o de 10 mmHg o más en la PA diastólica (PAD), tras 1 o 5 minutos de bipedestación. También se han recogido datos sobre enfermedades asociadas, sÃntomas en bipedestación, medicación utilizada, hábitos de los pacientes y resultados de otras exploraciones clÃnicas. La prevalencia global encontrada de HO fue del 14,6%. La prevalencia de HO sistólica tras un minuto (HO-S1) y tras 5 minutos (HO-S5) de bipedestación ha sido del 5,8% en ambas, y la de HO diastólica del 5,1% tras un minuto (HO-D1) y del 4,1% tras 5 minutos (HO-D5) de bipedestación. En el análisis de regresión logÃstica se encontró una asociación entre la existencia de HO global y la mayor elevación de la PA sistólica inicial, la presencia de sÃntomas de intolerancia ortostática (aunque sólo un 25,6% de los pacientes con HO presentaba sÃntomas) y el hábito tabáquico. Asimismo, se encontró una asociación con el uso de bloqueadores beta y antagonistas del calcio (diferentes de las dihidropiridinas) y la existencia de HO al minuto de bipedestación, y entre el consumo de tabaco y la HO a los 5 minutos de bipedestación.ConclusionesLa prevalencia detectada es alta y justifica la búsqueda sistemática de HO en los pacientes ancianos que son tratados de HTA en AP. La existencia de sÃntomas con el ortostatismo se relaciona con una mayor prevalencia de HO, pero sólo los presentó uno de cada 4 pacientes con HO. El consumo de tabaco podrÃa estar relacionado con la presencia de HO, asà como el uso de bloqueadores beta y antagonistas del calcio (diferentes de las dihidropiridinas).ObjectiveTo find the prevalence of orthostatic hypotension (OH) and associated factors in elderly hypertensive patients in a primary care setting.DesignDescriptive cross-sectional study.SettingLa Marina Health Centre (an urban centre in Santander).PatientsA random sample of 295 patients aged 65 years or older regularly assisted from hypertension.Measurements and main resultsMeasurements of sitting and standing blood pressure were obtained. Orthostatic hypotension was defined as 20 mmHg or greater decrease in systolic or 10 mmHg or greater decrease in diastolic blood pressure after 1-minute or 5-minute standing. Associated diseases, symptoms upon standing, medication use, habits and other clinical assessments were also recorded. The prevalence of OH was 14.6%. The prevalence of systolic OH after 1-minute (OH-S1) and after 5-minute (OH-S5) standing was 5.8% in both, and the diastolic OH was 5.1% after 1-minute (OH-D1) and 4.1% after 5-minute (OH-D5) standing. By logistic regression analysis, association between higher level of systolic blood pressure and global OH was found, also with the presence of orthostatic intolerance symptoms (although only 25.6% of the patients with OH showed symptoms) and smoking. Beta-blockers and calcium channel blockers (different from dihydropyridines) use was associated with OH after 1-minute standing and smoking with OH after 5-minute standing.ConclusionsThe detected prevalence is high and justifies the case finding of OH in elderly hypertensive patients in primary care. The symptoms of orthostatic intolerance are correlated with OH, but only 1 out of 4 patients showed symptoms. Smoking could be related with OH, so beta-blockers and calcium channel blockers (different from dihydropyridines) use
Resistencia a los antihelmÃnticos en bovinos del nordeste de Corrientes (Argentina)
El objetivo del trabajo fue determinar la prevalencia de la resistencia a los antiparasitarios contra los nematodes gastrointestinales de bovinos en el nordeste de Corrientes. El área de estudio comprendió 4 establecimientos ganaderos de los departamentos Ituzaingó y Santo Tomé. El periodo de estudio abarcó de marzo de 2014 a agosto de 2016. La unidad de análisis fue el ternero destete. El método utilizado fue el test de reducción del conteo de huevos. La prevalencia de la resistencia antihelmÃntica a la ivermectina en los 4 establecimientos ganaderos muestreados en este estudio fue del 100% y para el benzimidazol fue del 25%. Los géneros parasitarios resistentes a la ivermectina fueron Haemonchus y Cooperia. Estos resultados demuestran un aumento de la resistencia antihelmÃntica si se comparan con estudios previos realizados en otros lugares del paÃs
Critical properties of the measurement-induced transition in random quantum circuits
We numerically study the measurement-driven quantum phase transition of
Haar-random quantum circuits in dimensions. By analyzing the tripartite
mutual information we are able to make a precise estimate of the critical
measurement rate . We extract estimates for the associated bulk
critical exponents that are consistent with the values for percolation, as well
as those for stabilizer circuits, but differ from previous estimates for the
Haar-random case. Our estimates of the surface order parameter exponent appear
different from that for stabilizer circuits or percolation, but we are unable
to definitively rule out the scenario where all exponents in the three cases
match. Moreover, in the Haar case the prefactor for the entanglement entropies
depends strongly on the R\'enyi index ; for stabilizer circuits and
percolation this dependence is absent. Results on stabilizer circuits are used
to guide our study and identify measures with weak finite-size effects. We
discuss how our numerical estimates constrain theories of the transition.Comment: 6 pages + Supplemental materials (Updated with published version
Robust single machine scheduling with a flexible maintenance activity
In this paper, we address a problem arising in a manufacturing environment concerning the joint scheduling of multiple jobs and a maintenance activity on a single machine. Such activity must be processed within a given time window and its non-deterministic duration takes values in a given interval.We seek job schedules which are robust to any possible changes in the maintenance activity duration. We consider makespan and total completion time objectives under four different robustness criteria. We discuss a few properties and the complexity of finding robust schedules for the resulting eight problem scenarios.For the case of total completion time objective and maximum absolute regret criterion, we design and test exact and heuristic algorithms. The results of an extensive computational campaign, performed for assessing the performance of the proposed solution approaches, are reported. (C) 2019 Elsevier Ltd. All rights reserved
Seasonal dynamics in social behaviour and spacing patterns of the Little Owl Athene noctua
Most owl species exhibit territorial behaviour in order to have sufficient resources to maintain their fitness and biological success. The Little Owl (Athene noctua) has been considered a territorial species, although some authors have pointed to movements and social interactions outside a particular territory. We hypothesise that the spatial behaviour and social organisation of Little Owl follows a complex pattern, which varies throughout the year. We radio-tracked nine Little Owls in an area of 10 km(2) over nine months, paying particular attention to home range variation, social interaction and vocal behaviour. Home range size and overlap varied markedly throughout the year, with maximums in winter, and minimum size and overlap during the breeding season. Little Owls showed exclusive home ranges during the breeding season, whereas home range overlap was frequent in winter. Owls which had lost clutches increased their home ranges and shared the same foraging areas with other owls. Vocal activity was low all year round, except in the months immediately prior to courtship. Increase of vocal behaviour was therefore also associated with a reduction in home range