Gravitational decoherence: A general nonrelativistic model

We derive a general quantum master equation for the dynamics of a scalar bosonic particle interacting with a weak, stochastic and classical external gravitational field. The dynamics predicts decoherence in position, momentum and energy. We show how our master equation reproduces the results present in the literature by taking appropriate limits, thus explaining the apparent contradiction in their dynamical description. Our result is relevant in light of the increasing interest in the low energy quantum-gravity regime

Numerical simulation of the flow through an intermittent gas lift valve

The numerical simulation of the flow through a pilot valve used in the oil intermittent gas lift process is presented.The complexity of the non-isothermal compressible flow is modeled by the solution of the Navier-Stokes, Mass Conservation and Energy equations for the compressible flow. Numerical results and analyses pertaining to the flow dynamics through a 1½-inch pilot valve at an operating condition encountered in typical field operations are presente

Gravitational Decoherence and the Possibility of Its Interferometric Detection

We present a general master equation describing the quantum dynamics of a scalar bosonic field interacting with an external weak and stochastic gravitational field. The dynamics predicts decoherence both in position and in energy momentum. We show how the master equation reproduces, thus generalizing, the previous results in the literature by taking appropriate limits. We estimate the effect of gravitational decoherence in atom interferometers, providing also a straightforward way to assess the magnitude of the effect

Talbot-Lau effect beyond the point-particle approximation

Recent progress in matter-wave interferometry aims to directly probe the quantum properties of matter on ever increasing scales. However, in order to perform interferometric experiments with massive mesoscopic objects, taking into account the constraints on the experimental setups, the pointlike-particle approximation needs to be cast aside. In this work, we consider near-field interferometry based on the Talbot effects with a single optical grating for large spherical particles beyond the point-particle approximation. We account for the suppression of the coherent grating effect and, at the same time, the enhancement of the decoherence effects due to scattering and absorption of grating photons

Testing Dissipative Collapse Models with a Levitated Micromagnet

We present experimental tests of dissipative extensions of spontaneous wave function collapse models based on a levitated micromagnet with ultralow dissipation. The spherical micromagnet, with radius $R=27$ $\mu$m, is levitated by Meissner effect in a lead trap at $4.2$ K and its motion is detected by a SQUID. We perform accurate ringdown measurements on the vertical translational mode with frequency $57$ Hz, and infer the residual damping at vanishing pressure $\gamma/2\pi<9$ $\mu$Hz. From this upper limit we derive improved bounds on the dissipative versions of the CSL (continuous spontaneous localization) and the DP (Di\'{o}si-Penrose) models with proper choices of the reference mass. In particular, dissipative models give rise to an intrinsic damping of an isolated system with the effect parameterized by a temperature constant; the dissipative CSL model with temperatures below 1 nK is ruled out, while the dissipative DP model is excluded for temperatures below $10^{-13}$ K. Furthermore, we present the first bounds on dissipative effects in a more recent model, which relates the wave function collapse to fluctuations of a generalized complex-valued spacetime metric.Comment: 10 pages, 7 figure

Age-Related Differences in Cortical Activity during a Visuo-Spatial Working Memory Task with Facial Stimuli

Emotion, importantly displayed by facial expressions, is one of the most significant memory modulators. The interaction between memory and the different emotional valences change across lifespan, while young adults (YA) are expected to better recall negative events (Negativity Bias Hypothesis), older adults (OA) tend to focus on positive stimuli (Positivity Effect Hypothesis). This research work aims at verifying whether cortical electrical activity of these two age groups would also be differently influenced by emotional valences in a visuo-spatial working memory task. 27 YA (13 males) and 25 OA (14 males), all healthy volunteers, underwent electroencephalographic recordings (21 scalp electrodes montage), while performing the Spatial Delayed Recognition Span Task using a touch screen with different stimuli categories: neutral, positive and negative faces and geometric pictures. YA obtained higher scores than OA, and showed higher activation of theta and alpha bands in the frontal and midline regions, besides a more evident right-hemispheric asymmetry on alpha band when compared to OA. For both age groups, performance in the task was worse for positive faces than to negative and to neutral faces. Facial stimuli induced a better performance and higher alpha activation on the pre-frontal region for YA, and on the midline, occipital and left temporal regions for OA when compared to geometric figures. The superior performance of YA was expected due to the natural cognitive deficits connected to ageing, as was a better performance with facial stimuli due to the evolutionary importance of faces. These results were related to cortical activity on areas of importance for action-planning, decision making and sustained attention. Taken together, they are in accordance with the Negativity Bias but do not support the Positivity Effect. The methodology used was able to identify age-related differences in cortical activity during emotional mnemonic processing and may be interesting to future investigations

A revisited and general Kane’s formulation applied to very flexible multibody spacecraft

Abstract. Current space missions require predicting the spacecraft dynamics with considerable reliability. Among the various components of a spacecraft, subsystems like payload, structures, and power depend heavily on the dynamic behavior of the satellite during its operational life. Therefore, to ensure that the results obtained through numerical simulations correspond to the actual behavior, an accurate dynamical model must be developed. In this context, an implementation of Kane’s method is presented to derive the dynamical equations of a spacecraft composed of both rigid and flexible bodies connected via joints in tree topology. Starting from the kinematics of two generic interconnected bodies, a systematic approach is derived and the recursive structure of the equations is investigated. The Kane’s formulation allows a relatively simple derivation of the equation of motion while obtaining the minimum set of differential equations, which implies lower computational time. On the other hand, this formulation excludes reaction forces and torques from the dynamical equations. Nevertheless, in this work a strategy to compute them a posteriori without further numerical integrations is presented. Flexibility is introduced through the standard modal decomposition technique, so that modal shapes obtained by FEA software can be directly utilized to characterize the elastic motion of the flexible bodies. A spacecraft composed of a rigid bus and several flexible appendages is modeled and numerical simulations point out that this systematic method is very effective for this illustrative example

Testing the foundation of quantum physics in space via Interferometric and non-interferometric experiments with mesoscopic nanoparticles

Quantum technologies are opening novel avenues for applied and fundamental science at an impressive pace. In this perspective article, we focus on the promises coming from the combination of quantum technologies and space science to test the very foundations of quantum physics and, possibly, new physics. In particular, we survey the field of mesoscopic superpositions of nanoparticles and the potential of interferometric and non-interferometric experiments in space for the investigation of the superposition principle of quantum mechanics and the quantum-to-classical transition. We delve into the possibilities offered by the state-of-the-art of nanoparticle physics projected in the space environment and discuss the numerous challenges, and the corresponding potential advancements, that the space environment presents. In doing this, we also offer an ab-initio estimate of the potential of space-based interferometry with some of the largest systems ever considered and show that there is room for tests of quantum mechanics at an unprecedented level of detail

An antiviral trap made of protein nanofibrils and iron oxyhydroxide nanoparticles

Minimizing the spread of viruses in the environment is the first defence line when fighting outbreaks and pandemics, but the current COVID-19 pandemic demonstrates how difficult this is on a global scale, particularly in a sustainable and environmentally friendly way. Here we introduce and develop a sustainable and biodegradable antiviral filtration membrane composed of amyloid nanofibrils made from food-grade milk proteins and iron oxyhydroxide nanoparticles synthesized in situ from iron salts by simple pH tuning. Thus, all the membrane components are made of environmentally friendly, non-toxic and widely available materials. The membrane has outstanding efficacy against a broad range of viruses, which include enveloped, non-enveloped, airborne and waterborne viruses, such as SARS-CoV-2, H1N1 (the influenza A virus strain responsible for the swine flu pandemic in 2009) and enterovirus 71 (a non-enveloped virus resistant to harsh conditions, such as highly acidic pH), which highlights a possible role in fighting the current and future viral outbreaks and pandemics

EFFECTS OF EMOTIONAL CONTENT ON DECLARATIVE MEMORY: TWO STUDIES CONDUCTED ON HEALTHY SUBJECTS AND CEPHALALGIC PATIENTS

RESUMEN Varios estudios sugieren que el despertar emocional puede promover el almacenamiento de información en la memoria. Nosotros reportamos dos estudios evaluando los efectos del contenido emocional sobre la memoria declarativa, efectuados con sujetos sanos y pacientes cefalálgicos. Utilizamos una adaptación de dos versiones del mismo relato, con diferentes propiedades (neutral o emocional), la cual ha sido previamente empleada en experimentos que abordan los efectos de mejoría sobre la retención de la memoria causados por las emociones. En el primer estudio, efectuado en estudiantes sanos, empleamos potenciales relacionados a eventos (PRE) para evaluar si existe una lateralización hemisférica relacionada al sexo, de los potenciales eléctricos producidos por el contenido emocional de un relato. Comparamos las ondas P300 de los hemisferios izquierdo y derecho, registrados en los sitios correspondientes a los electrodos P3 y P4, en respuesta a estímulos neutrales o emocionales en hombres y mujeres. Los estímulos emocionales produjeron un P300 mayor, medido tanto por la amplitud como por la latencia del potencial, en el hemisferio izquierdo de mujeres comparado con el de los hombres, sin embargo, produjeron un P300 mayor en el hemisferio derecho en los hombres comparado con el de las mujeres. La mejoría en la memoria, originada por el contenido emocional de la información, puede estar relacionada con el diferencial del componente P300 durante la codificación. Estos datos indican que tanto el sexo como la lateralización hemisférica constituyen importantes factores que interactúan para influenciar tanto a los correlatos neurales de las emociones como a la memoria influenciada emocionalmente.En el segundo estudio evaluamos la influencia del mismo estímulo emocional, utilizado en el primer estudio, sobre la memoria declarativa de pacientes cefalálgicos, que padecen migraña, divididos en dos grupos: migrañosos sin ningún tratamiento y migrañosos tratados con el antidepresivo amitriptilina. No se efectúo análisis de los PRE en esta parte de la investigación. Los hallazgos del presente experimento sugieren que la migraña crónica es asociada con deterioros en la memoria. Considerando que la migraña se asocia con depresión mayor, la presente investigación evaluó también el efecto del antidepresivo amitriptilina. Nuestros resultados mostraron que la amitriptilina tiene un efecto dañino sobre la memoria. De hecho, en nuestro estudio los migrañosos sin tratamiento recordaron la parte más emotiva del relato, de manera significativamente mejor comparados con los migrañosos tratados con amitriptilina. Por lo tanto, nuestros datos sugieren que la amitriptilina bloquea los efectos de mejoría sobre el procesamiento de la memoria causados por el contenido emocional de la información. Palabras clave: Memoria emocional, potenciales relacionados a eventos, componente P300, migraña, amitriptilina. ABSTRACT Several studies suggest that emotional arousal can promote memory storage. We report two studies evaluating the effects of emotional content on declarative memory, conducted with healthy subjects and cephalgic patients. We utilized an adaptation of two versions of the same story, with different arousing properties (neutral or emotional), which have been already employed in experiments involving the enhancing effects of emotions on memory retention. In the first study, conducted on healthy students, we used event related potentials (ERP) to evaluate whether there is a sex-related hemispheric lateralization of electrical potentials elicited by the emotional content of a story. We compared left and right hemisphere P300 waves, recorded in P3 and P4 electrode sites, in response to emotional or neutral stimuli in men and women. In the left hemisphere, emotional stimuli elicited a stronger P300 in women, compared to men, as indexed by both amplitude and latency measures; moreover, the emotional content of the story elicited a stronger P300 in the right hemisphere in men than in women. The better memory for the arousal material may be related to the differential P300 at encoding. These data indicate that both sex and cerebral hemisphere constitute important, interacting influences on neural correlates of emotion, and of emotionally influenced memory.In the second study we evaluated the influence of the same emotional stimuli, utilized in the first study, on declarative memory on cephalalgic patients, suffering from migraine headache, divided in 2 groups: migraineurs without any treatment and migraineurs treated with the antidepressant amitriptyline. No ERP analysis was performed in this part of research. The findings of the present experiments suggest that chronic migraine is associated with memory impairment. Taking into account that migraine is associated with major depression, in the present research the effect of the antidepressant amitriptyline was also evaluated. Our results showed that amitriptyline has an impairment effect on memory. In fact, in our study the untreated migraineurs recalled the most emotional phase of the arousal story significantly better compared to migraineurs treated with amitriptyline. Then, our data suggest that amitriptyline prevents the enhancing effects of emotional content on memory processes. Key words: emotional memory, event related potentials, P300 wave, migraine, amitriptyline