Erratum: Viscous to Inertial Transition in Dense Granular Suspension [Phys. Rev. Lett. 129, 078001 (2022)].

This corrects the article DOI: 10.1103/PhysRevLett.129.078001.

Viscous to Inertial Transition in Dense Granular Suspension.

Granular suspensions present a transition from a Newtonian rheology in the Stokes limit to a Bagnoldian rheology when inertia is increased. A custom rheometer that can be run in a pressure- or a volume-imposed mode is used to examine this transition in the dense regime close to jamming. By varying systematically the interstitial fluid, shear rate, and packing fraction in volume-imposed measurements, we show that the transition takes place at a Stokes number of 10 independent of the packing fraction. Using pressure-imposed rheometry, we investigate whether the inertial and viscous regimes can be unified as a function of a single dimensionless number based on stress additivity.

Electrophysiological assessment of water stress in fruit-bearing woody plants.

Development and evaluation of a real-time plant water stress sensor, based on the electrophysiological behavior of fruit-bearing woody plants is presented. Continuous electric potentials are measured in tree trunks for different irrigation schedules, inducing variable water stress conditions; results are discussed in relation to soil water content and micro-atmospheric evaporative demand, determined continuously by conventional sensors, correlating this information with tree electric potential measurements. Systematic and differentiable patterns of electric potentials for water-stressed and no-stressed trees in 2 fruit species are presented. Early detection and recovery dynamics of water stress conditions can also be monitored with these electrophysiology sensors, which enable continuous and non-destructive measurements for efficient irrigation scheduling throughout the year. The experiment is developed under controlled conditions, in Faraday cages located at a greenhouse area, both in Persea americana and Prunus domestica plants. Soil moisture evolution is controlled using capacitance sensors and solar radiation, temperature, relative humidity, wind intensity and direction are continuously registered with accurate weather sensors, in a micro-agrometeorological automatic station located at the experimental site. The electrophysiological sensor has two stainless steel electrodes (measuring/reference), inserted on the stem; a high precision Keithley 2701 digital multimeter is used to measure plant electrical signals; an algorithm written in MatLab(®), allows correlating the signal to environmental variables. An electric cyclic behavior is observed (circadian cycle) in the experimental plants. For non-irrigated plants, the electrical signal shows a time positive slope and then, a negative slope after restarting irrigation throughout a rather extended recovery process, before reaching a stable electrical signal with zero slope. Well-watered plants presented a continuous signal with daily maximum and a minimum EP of similar magnitude in time, with zero slope. This plant electrical behavior is proposed for the development of a sensor measuring real-time plant water status.

An updated review on burden on caregivers of schizophrenia patients / Una revisión actualizada sobre la sobrecarga en cuidadores de pacientes con esquizofrenia

BACKGROUND: Schizophrenia is a debilitating mental illness that has a significant impact not only in the patient but also in the entire family as well. Caregivers assume almost the totality of the patient care. This responsibility exposes caregivers to an intense burden with negative consequences for them and the rest of the family system. This is an updated review of existing literature about burden on families with schizophrenia patients. METHOD: An electronic search of articles from MEDLINE, EMBASE, APA, EBSCO, and Cochrane databases was conducted for articles published between 2008 and 2013. RESULTS: A systematization of information and frequency analysis revealed the existence of eight factors related to burden that were present in almost all the reviewed literature: Programs of family treatment, Ethnic group, Expressed Emotion, Stress and Burden, Preoccupations of the caregiver, Kind of caregiver, Social networks, Social support, Finances and Coping Strategies. CONCLUSIONS: This study supports the statements of different theories reflecting the complexity of schizophrenia caregivers' burden and these, in turn, may be related to the above factors

ANTECEDENTES: la esquizofrenia es una enfermedad mental grave que no solo tiene un impacto significativo en el paciente, sino también en la familia. Los cuidadores asumen casi la totalidad de los cuidados de los pacientes. Esta responsabilidad expone a los cuidadores a una intensa sobrecarga con consecuencias negativas para ellos y el resto del sistema familiar. Este estudio se trata de una revisión actualizada de la bibliografía existente acerca de la sobrecarga en familias con pacientes con esquizofrenia. MÉTODO: se realizó una búsqueda electrónica de artículos de bases de datos MEDLINE, EMBASE, APA, EBSCO y Cochrane para artículos publicados entre 2008 y 2013. RESULTADOS: una sistematización de la información y un análisis de frecuencia reveló la existencia de ocho factores relacionados con la sobrecarga que se presentaron en casi toda la literatura revisada: programas de tratamiento familiar, grupo étnico, Emoción Expresada, estrés y sobrecarga, preocupaciones del cuidador, tipo de persona que lo cuida, redes sociales, apoyo social, finanzas y estrategias de afrontamiento. CONCLUSIONES: este estudio evidencia el apoyo a las diversas teorías planteadas sobre el tema, reflejando la complejidad de la relación de los factores mencionados anteriormente en la sobrecarga de los cuidadores de pacientes con esquizofrenia

An updated review on burden on caregivers of schizophrenia patients.

BACKGROUND: Schizophrenia is a debilitating mental illness that has a significant impact not only in the patient but also in the entire family as well. Caregivers assume almost the totality of the patient care. This responsibility exposes caregivers to an intense burden with negative consequences for them and the rest of the family system. This is an updated review of existing literature about burden on families with schizophrenia patients. METHOD: An electronic search of articles from MEDLINE, EMBASE, APA, EBSCO, and Cochrane databases was conducted for articles published between 2008 and 2013. RESULTS: A systematization of information and frequency analysis revealed the existence of eight factors related to burden that were present in almost all the reviewed literature: Programs of family treatment, Ethnic group, Expressed Emotion, Stress and Burden, Preoccupations of the caregiver, Kind of caregiver, Social networks, Social support, Finances and Coping Strategies. CONCLUSIONS: This study supports the statements of different theories reflecting the complexity of schizophrenia caregivers' burden and these, in turn, may be related to the above factors.

Estrategias de inserción laboral en población con discapacidad mental: una revisión / Strategies of employability in population with mental disabilities: a review

The employability and access to the productive market are considered key elements for the full integration of the patient with mental disability. The aim of this review was to describe and analyze the scientific literature for the main employability strategies: traditional vocational rehabilitation (sheltered work and social firms) and supported employment (particularly in its mode of individualized supported employment). The results of the review suggest that individualized supported employment is the most effective approach in obtaining employment for people with mental disabilities.

La inserción laboral y el acceso al mercado productivo son considerados elementos claves para la plena integración del paciente con discapacidad mental. El objetivo de la presente revisión fue describir y analizar la literatura científica correspondiente a las principales estrategias de inserción laboral: rehabilitación vocacional tradicional (empleo protegido y empresas sociales) y empleo con apoyo (particularmente en su modalidad de empleo con apoyo individualizado). Los resultados de la revisión indican que el empleo con apoyo individualizado es el abordaje más efectivo en la obtención de empleo en personas con discapacidad mental.

Implementación de un programa de estimulación cognitiva en personas con demencia tipo Alzheimer: un estudio piloto en chilenos de la tercera edad / Implementation of a Cognitive Stimulation Program for People with Alzheimer Disease: A Pilot Study in a Chilean Elderly Sample

La Terapia de Estimulación Cognitiva (TEC) es una intervención psicosocial para personas con demencia que ha obtenido buenos resultados en población anglosajona. El objetivo de este estudio fue evaluar la eficacia de la TEC en una muestra de personas chilenas. Participaron 22 pacientes con diagnóstico de Enfermedad de Alzheimer (EA) en fase leve a moderada, pertenecientes a un centro asistencial de la ciudad de Quillota, Chile. Para determinar la eficacia del programa, se definió un diseño experimental mixto 2x2 de medidas repetidas, asignándose aleatoriamente la muestra a dos grupos: intervención (GI) y control (GC). Se establecieron tres dimensiones para evaluar: cognición, calidad de vida y capacidad funcional de la persona con demencia. Posterior a la intervención, el GI presentó una mejoría significativa en sus indicadores de deterioro cognitivo y calidad de vida; por el contrario, el GC no evidenció cambios positivos en ninguna dimensión, empeorando el declive cognitivo. Ninguno de los grupos experimentó cambios significativos en la capacidad funcional. Si bien en la comparación intergrupo no existieron diferencias significativas en ninguna variable, el GI presentó una mejoría sustancial de la función cognitiva, en comparación con el aumento en la progresión del deterioro cognitivo en el GC. Se recomienda que futuras investigaciones contrasten dichos resultados utilizando una muestra más grande de personas con EA.

Cognitive Stimulation Therapy (CST) is a psychosocial intervention for people with dementia that has been successful in Anglo-Saxon population. The aim of this study was to assess the effectiveness of CST in a sample of Chilean elders. The participants were 22 patients diagnosed with Alzheimer's disease (AD) in mild to moderate stage, who were living in a residential care home in the town of Quillota, Chile. In order to determine the effectiveness of the program, an experimental mixed design 2x2 (repeated measures) was employed. The sample was randomly assigned into two groups: intervention group (IG) and control group (CG). Three dimensions were assessed: cognition, quality of life and functional ability. After the intervention, the IG presented a significant improvement in their cognitive function and quality life. In contrast, the CG did not show positive changes in any dimension. In fact, CG showed a worsening in its cognitive deterioration. Both groups did not showed significant changes in functional ability. Even though intergroup comparisons did not yield significant differences, the IG showed an important improvement in cognitive function, compared with an increase in the progression of cognitive impairment in the CG. It is recommended that future research will contrast these results using a larger sample of people with AD.

Effect of packing fraction on shear band formation in a granular material forced by a penetrometer.

Granular ensembles subjected to confinement forces can reach metastable states that often break down via formation of shear bands for sufficiently high deviatoric stress. In this article we investigate the flow induced in a granular ensemble that is perturbed by a vertically moving finger in a quasiplanar geometry. The flow exhibits spiral-like shear bands and evolves discontinuously in time, in concert with an oscillating penetration force. We characterize the nature of this nucleation-relaxation type process for loose to dense packing fractions. The nucleation dynamics is reasonably well described by a simple Mohr-Coulomb failure criterium in which the friction coefficient is a function of packing fraction. We contrast our findings with the recent work of Gravish et al. [Phys. Rev. Lett. 105, 128301 (2010)].

Dynamics of shear bands in a dense granular material forced by a slowly moving rigid body.

We experimentally investigate the flow field in plane geometry around a slowly moving rigid finger in a dry, randomly packed granular medium. The finger enters the medium vertically from its free surface, in analogy with indentation tests on ductile materials. By developing a particle imaging velocimetry technique, we identify a localized flow around the finger, limited by two nearly symmetric shear bands that nucleate near the fingertip and reach the free surface of the granular compact. Evolution of the shear bands is discontinuous, exhibiting nucleation-relaxation processes as the finger moves downward. We present a simple model accounting for the shape of the shear bands at early stages of nucleation. We measure the force applied by the finger and the sources of dilation as well. A mechanism that relates local dilations to the total volume increase of the medium is proposed.

Wave localization in strongly nonlinear Hertzian chains with mass defect.

We report observations of mechanical energy localization in a strongly nonlinear discrete lattice. The experimental setup we consider is a one-dimensional nonloaded horizontal chain of identical spheres interacting via the nonlinear Hertz potential which contains a mass defect. Our experiments show that the interaction of a solitary wave with a light intruder excites a nonlinear localized mode. In agreement with dimensional analysis, we find that the frequency of localized oscillations exceeds the incident wave frequency spectrum and nonlinearly depends on incident wave strength and on mass and size of the intruder. The absence of tensile stress between grains allows some gaps to open, which in turn induces a significant enhancement of the amplitude of oscillations. We performed numerical simulations that precisely describe our observations without any adjusting parameters.

Nonlinear waves in dry and wet Hertzian granular chains.

A one-dimensional dry granular medium, a chain of beads which interact via the nonlinear Hertz potential, exhibits strongly nonlinear behaviors. When such an alignment further contains some fluid in the interstices between grains, it may exhibit new interesting features. We report some recent experiments, analysis and numerical simulations concerning nonlinear wave propagation in dry and wet chains of spheres. We consider first a monodisperse chain as a reference case. We then analyze how the pulse characteristics are modified in the presence of an interstitial viscous fluid. The fluid not only induces dissipation but also strongly affect the intergrain stiffness: in a wet chain, wave speed is enhanced and pulses are shorter. Simple experiments performed with a single sphere colliding a wall covered by a thin film of fluid confirm these observations. We demonstrate that even a very small amount of fluid can overcome the Hertzian potential and is responsible for a large increase of contact stiffness. Possible mechanisms for wet contact hardening are related to large fluid shear rate during fast elastohydrodynamic collision between grains.

Experimental evidence of shock mitigation in a Hertzian tapered chain.

We present an experimental study of the mechanical impulse propagation through a horizontal alignment of elastic spheres of progressively decreasing diameter phi(n): namely, a tapered chain. Experimentally, the diameters of spheres which interact via the Hertz potential are selected to keep as close as possible to an exponential decrease, phi(n+1) = (1-q)phi(n), where the experimental tapering factor is either q(1) approximately equal to 5.60% or q(2) approximately equal to 8.27%. In agreement with recent numerical results, an impulse initiated in a monodisperse chain (a chain of identical beads) propagates without shape changes and progressively transfers its energy and momentum to a propagating tail when it further travels in a tapered chain. As a result, the front pulse of this wave decreases in amplitude and accelerates. Both effects are satisfactorily described by the hard-sphere approximation, and basically, the shock mitigation is due to partial transmissions, from one bead to the next, of momentum and energy of the front pulse. In addition when small dissipation is included, better agreement with experiments is found. A close analysis of the loading part of the experimental pulses demonstrates that the front wave adopts a self-similar solution as it propagates in the tapered chain. Finally, our results corroborate the capability of these chains to thermalize propagating impulses and thereby act as shock absorbing devices.