On the optimaL response of q-vortex

Wingtip vortices represent a hazard for the stability of the following airplane in airport highways. These flows have been usually modeled as swirling jets/wakes, which are known to be highly unstable and susceptible to breakdown at high Reynolds numbers for certain flow conditions, but different to the ones present in real flying airplanes. A very recent study based on Direct Numerical Simulations (DNS) shows that a large variety of helical responses can be excited and amplified when a harmonic inlet forcing is imposed. In this work, the optimal response of q-vortex (both axial vorticity and axial velocity can be modeled by a Gaussian profile) is studied by considering the time-harmonically forced problem with a certain frequency ω. We first reproduce Guo and Sun’s results for the Lamb-Oseen vortex (no axial flow) to validate our numerical code. In the axisymmetric case m = 0, the system response is the largest when the input frequency is null. The axial flow has a weak influence in the response for any axial velocity intensity. We also consider helical perturbations |m| = 1. These perturbations are excited through a resonance mechanism at moderate and large wavelengths as it is shown in Figure 1. In addition, Figure 2 shows that the frequency at which the optimal gain is obtained is not a continuous function of the axial wavenumber k. At smaller wavelengths, large response is excited by steady forcing. Regarding the axial flow, the unstable response is the largest when the axial velocity intensity, 1/q, is near to zero. For perturbations with higher azimuthal wavenumbers |m| > 1, the magnitudes of the response are smaller than those for helical modes. In order to establish an alternative validation, DNS has been carried out by using a pseudospectral Fourier formulation finding a very good agreement.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Nanostructures with Group IV nanocrystals obtained by LPCVD and thermal annealing of SiGeO layers

Nanocrystals embedded in an oxide matrix have been fabricated by annealing SiGeO films deposited by LPCVD. The composition of the oxide layers and its evolution after annealing as well as the presence and nature of nanocrystals in the films have been studied by several experimental techniques. The results are analyzed and discussed in terms of the main deposition parameters and the annealing temperature

Experimental lateral wall boundary layer behavior of a differentially rotating split-cylinder flow

The cylindrical wall boundary layer of a closed cylinder split in two halves at the equator is studied experimentally. When these two parts rotate in exact corotation the internal flow is essentially in solid-body rotation at the angular velocity of both halves. When a slight difference between the rotation frequencies is established a secondary flow is created due to the differential rotation between both sides and restricted to the boundary layer. This behavior of the boundary layer is compared with theoretical and numerical results finding the ¿sandwich¿ structure of a Stewartson boundary layer. Time-dependent waves are observed near the cylindrical wall. Their behavior for different values of the control parameters are presented. Finally, a global recirculation mode is also found due to a symmetry-breaking induced between sides that appears because of a slight misalignment of the experimental setup, whose characteristics are compatible with the behavior of a precessing cylinder

Raman Spectroscopy of group IV nanostructured semiconductors: influence of size, temperature and stress.

Group IV nanostructures have attracted a great deal of attention because of their potential applications in optoelectronics and nanodevices. Raman spectroscopy has been extensively used to characterize nanostructures since it provides non destructive information about their size, by the adequate modeling of the phonon confinement effect. However, the Raman spectrum is also sensitive to other factors, as stress and temperature, which can mix with the size effects borrowing the interpretation of the Raman spectrum. We present herein an analysis of the Raman spectra obtained for Si nanowires; the influence of the excitation conditions and the heat dissipation media are discussed in order to optimize the experimental conditions for reliable spectra acquisition and interpretation

Epsilon iron oxide: Origin of the high coercivity stable low Curie temperature magnetic phase found in heated archeological materials

The identification of epsilon iron oxide (-Fe2O3) as the low Curie temperature high coercivity stable phase (HCSLT) carrying the remanence in heated archeological samples has been achieved in samples from two archeological sites that exhibited the clearest evidence of the presence of the HCSLT. This uncommon iron oxide has been detected by Confocal Raman Spectroscopy (CRS) and characterized by rock magnetic measurements. Large numbers of -Fe2O3 microaggregates (in CO) or isolated clusters (in HEL) could be recognized, distributed over the whole sample, and embedded within the ceramic matrix, along with hematite and pseudobrookite and with minor amounts of anatase, rutile, and maghemite. Curie temperature estimates of around 170 degrees C for CO and 190 degrees C for HEL are lower than for pure, synthetic -Fe2O3 (227 degrees C). This, together with structural differences between the Raman spectra of the archeologically derived and synthetic samples, is likely due to Ti substitution in the -Fe2O3 crystal lattice. The -Fe2O3--Fe2O3--Fe2O3 transformation series has been recognized in heated archeological samples, which may have implications in terms of their thermal history and in the factors that govern the formation of -Fe2O3

Si and SixGe1-x NWs studied by Raman spectroscopy

Group IV nanostructures have attracted a great deal of attention because of their potential applications in optoelectronics and nanodevices. Raman spectroscopy has been extensively used to characterize nanostructures since it provides non destructive information about their size, by the adequate modeling of the phonon confinement effect. The Raman spectrum is also sensitive to other factors, as stress and temperature, which can mix with the size effects borrowing the interpretation of the Raman spectrum. We present herein an analysis of the Raman spectra obtained for Si and SiGe nanowires; the influence of the excitation conditions and the heat dissipation media are discussed in order to optimize the experimental conditions for reliable spectra acquisition and interpretation

Raman spectroscopy study of group IV semiconductor nanowires

Group IV nanostructures have attracted a great deal of attention because of their potential applications in optoelectronics and nanodevices. Raman spectroscopy has been extensively used to characterize nanostructures since it provides non destructive information about their size, by the adequate modeling of the phonon confinement effect. However, the Raman spectrum is also sensitive to other factors, as stress and temperature, which can mix with the size effects borrowing the interpretation of the Raman spectrum. We present herein an analysis of the Raman spectra obtained for SiGe nanowires; the influence of the excitation conditions and the heat dissipation media are discussed in order to optimize the experimental conditions for reliable spectra acquisition and interpretation. The interpretation of the data is supported by the calculation of the temperature inside the NWs with different diameters

Increase in Video Consultations During the COVID-19 Pandemic: Healthcare Professionals’ Perceptions about Their Implementation and Adequate Management

In response to the COVID-19 pandemic, health care modalities such as video consultations have been rapidly developed to provide safe health care and to minimize the risk of spread. The purpose of our study is to explore Spanish healthcare professionals’ perceptions about the implementation of video consultations. Based on the testimonies of 53 professionals, different categories emerged related to the four identified themes: benefits of video consultations (for professionals, patients, and the health system, and compared to phone calls), negative aspects (inherent to new technologies and the risk of a perceived distancing from the professional), difficulties associated with the implementation of video consultations (technological difficulties, lack of technical skills and refusal to use video consultation among professionals and patients), and the need for training (technological, nontechnical, and social-emotional skills, and adaptation of technical skills). Additionally, the interviewees indicated that this new modality of health care may be extended to a broader variety of patients and clinical settings. Therefore, since video consultations are becoming more widespread, it would be advisable for health policies and systems to support this modality of health care, promoting their implementation and guaranteeing their operability, equal access and quality

A Physical optics simulator for multireflector THz imaging systems

This article presents a physical optics-based simulator for the analysis of terahertz (THz) imaging systems. The simulation starts by calculating the electromagnetic interactions inside the multireflector system and the incident field that the focusing system creates on the target under inspection. In a second step, the electric field that the modeled target scatters back to the system receiver, is also calculated. This allows to predict the imaging behavior of the system for different targets before manufacturing. The simulator results are validated by using measurements from an existing 300-GHz standoff imaging system. This contribution aims to help in the development of better imaging systems for security applications in the near future.Atlantic Research Center for Information and Communication TechnologiesMinisterio de Economía y Competitividad | Ref. TEC2015-65353-RMinisterio de Economía y Competitividad | Ref. TEC2015-73908-JINAgencia Estatal de Investigación | Ref. TEC2017-87061-C3-1-RXunta de Galicia | Ref. GRC2015/01

Unveiling the Synergistic Interplay of Neuropeptides for Novel Therapeutic Approaches in Neurodegenerative and Depressive Disorders.

The intricate relationship between hippocampal neurogenesis dysregulation and neurodegenerative diseases such as Alzheimer's, as well as depression, has sparked an urgent call for innovative therapeutic strategies. Our groundbreaking study delves into the interaction of Neuropeptide Y (NPY) and galanin (GAL) agonists, two neuromodulatory systems with a substantial presence in the limbic system, and their potential neurogenic impact on both the dorsal and ventral hippocampus. Through meticulous examination of the subchronic e"ects of NPY Y1 (Y1R) and GAL2 (GALR2) agonists on hippocampal cell proliferation, survival, and neuroprotective factor expression, we reveal a fascinating cascade of cellular responses. These include increased cell proliferation (PCNA), enhanced hippocampal cell survival (BrdU), and induction of neuroprotective factors (BDNF). Our functional assessment showcases the resulting improvements in spatial memory performance in the object-in-place task and antidepressant-like e"ects in the forced swimming test. These outcomes are attributed to the synergistic interaction between Y1R and GALR2 receptors, which promote neuronal survival and neurite outgrowth in hippocampal cells. This pioneering research paves the way for the development of heterobivalent agonist pharmacophores that target Y1R-GALR2 heterocomplexes. By acting on neuronal precursor cells in the dentate gyrus of the dorsal hippocampus, these novel compounds hold immense promise as transformative therapies for cognitive and a"ective impairments in neurodegenerative and depressive diseases.Supported by the Proy_Excel_2021_0613 (Junta de Andalucía) and Proyecto Puente (B4-2021) (UMA), Spain to MN. Swedish Medical Research Council, Sweden (62X-00715-50-3), to KF, by Stiftelsen Olle Engkvist Byggmästare to KF, and by Hjärnfonden, Sweden (F02018-0286), Hjärnfonden, Sweden (F02019-0296) and EMERGIA2020 (Junta de Andalucía), to DOBE. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech