The continuum of metastable conical states of monoaxial chiral helimagnets

At low temperature and zero applied magnetic field, besides the equilibrium helical state, monoaxial chiral helimagnets have a continuum of helical states differing by the wave number of the modulation. The wave number of these states in units of the equilibrium state wave number is denoted here by p, and accordingly the corresponding states are called the p-states. In this work we study in detail the metastability of the p-states. The application of an external magnetic field in the direction of the chiral axis has a double effect: on one hand, it introduces a conical deformation of the p-states, and on the other hand it destabilizes some of them, shrinking the range of p in which the p-states are metastable. If a polarized current is applied along the chiral axis, the p-states reach a steady moving state with a constant velocity proportional to the current intensity. Besides this dynamical effect, the polarized current also induces a conical deformation and reduces the range of stability of the p-states. The stability diagram in the plane applied field - applied current intensity has interesting features that, among other things, permit the manipulation of p-states by a combination of applied fields and currents. These features can be exploited to devise processes to switch between p-states. In particular there are p-states with negative p, opening the possibility to helicity switching. The theoretical feasibility of such processes, crucial from the point of view of applications, is shown by micromagnetic simulations. Analogous $p$-states exists in cubic chiral helimagnets and therefore similar effects are expected in those systems.Comment: 13 pages, 7 figure

Regional economic dynamics and convergence in the european union

[eng] Deepening in the European Union (EU) integration process has enhanced the question of economic disparities at a regional level. The convergence process observed until the late seventies was exhausted onwards in coincidence with important changes in the economic activity. The paper showshow these factors would have provoked a regional differenciated response that,despite being important, would have not strengthened the decrease in regional inequalities. We use an alternative and (in our opinion) richer approach to the traditional convergence analysis, where the evolution of the whole regional distribution is what matters and not that of a representative economy. Moreover, when analysing inequalities among regional economies, the geographical space acquire an outstanding role. Hence, we apply spatial association tests and relate them to the convergence analysis[spa] El avance en el proceso de integración ha aumentado el interés por la evolución de las disparidades económicas entre las regiones de la Unión Europea. El proceso de convergencia observado hasta finales de los setenta parece haberse agotado, coincidiendo con importantes cambios en el desarrollo de la actividad económica. El trabajo muestra como estos factores habrían provocado una respuesta regional diferenciada que, pese a ser importante, no habría contribuido a la disminución de las disparidades. En el trabajo se utiliza una aproximación alternativa a la empleada en el tradicional análisis de convergencia, donde lo que se considera es la evolución de la totalidad de la distribución y no unicamente aquélla de una economía representativa. Adicionalmente, cuando se estudian las disparidades entre economías regionales, el espacio adquiere un papel destacado. Por ello se aplican contrastes de asociación espacial y se relacionan con el análisis de convergenci

A novel approach for adapting the standard addition method to single particle-ICP-MS for the accurate determination of NP size and number concentration in complex matrices; 35414390

This paper presents a novel approach, based on the standard addition method, for overcoming the matrix effects that often hamper the accurate characterization of nanoparticles (NPs) in complex samples via single particle inductively coupled plasma mass spectrometry (SP-ICP-MS). In this approach, calibration of the particle size is performed by two different methods: (i) by spiking a suspension of NPs standards of known size containing the analyte, or (ii) by spiking the sample with ionic standards; either way, the measured sensitivity is used in combination with the transport efficiency (TE) for sizing the NPs. Moreover, such transport efficiency can be readily obtained from the data obtained via both calibration methods mentioned above, so that the particle number concentration can also be determined. The addition of both ionic and NP standards can be performed on-line, by using a T-piece with two inlet lines of different dimensions. The smaller of the two is used for the standards, thus ensuring a constant and minimal sample dilution. As a result of the spiking of the samples, mixed histograms including the signal of the sample and that of the standards are obtained. However, the use of signal deconvolution approaches permits to extract the information, even in cases of signal populations overlapping. For proofing the concept, characterization of a 50 nm AuNPs suspension prepared in three different media (i.e., deionized water, 5% ethanol, and 2.5% tetramethyl ammonium hydroxide-TMAH) was carried out. Accurate results were obtained in all cases, in spite of the matrix effects detected in some media. Overall, the approach proposed offers flexibility, so it can be adapted to different situations, but it might be specially indicated for samples for which the matrix is not fully known and/or dilution is not possible/recommended. © 2022 The Author

Sensitivity and specificity of the Patient Health Questionnaire (PHQ-9, PHQ-8, PHQ-2) and General Anxiety Disorder scale (GAD-7, GAD-2) for depression and anxiety diagnosis: a cross-sectional study in a Peruvian hospital population

OBJECTIVES: The Patient Health Questionnaire (PHQ) and Generalised Anxiety Disorder Scale (GAD) are widely used screening tools, but their sensitivity and specificity in low-income and middle-income countries are lower than in high-income countries. We conducted a study to determine the sensitivity and specificity of different versions of these scales in a Peruvian hospital population. DESIGN: Our study has a cross-sectional design. SETTING: Our participants are hospitalised patients in a Peruvian hospital. The gold standard was a clinical psychiatric interview following ICD-10 criteria for depression (F32.0, F32.1, F32.2 and F32.3) and anxiety (F41.0 and F41.1). PARTICIPANTS: The sample included 1347 participants. A total of 334 participants (24.8%) were diagnosed with depression, and 28 participants (2.1%) were diagnosed with anxiety. RESULTS: The PHQ-9's≥7 cut-off point showed the highest simultaneous sensitivity and specificity when contrasted against a psychiatric diagnosis of depression. For a similar contrast against the gold standard, the other optimal cut-off points were: ≥7 for the PHQ-8 and ≥2 for the PHQ-2. In particular, the cut-off point ≥8 had good performance for GAD-7 with sensitivity and specificity, and cut-off point ≥10 had lower levels of sensitivity, but higher levels of specificity, compared with the cut-off point of ≥8. Also, we present the sensitivity and specificity values of each cut-off point in PHQ-9, PHQ-8, PHQ-2, GAD-7 and GAD-2. We confirmed the adequacy of a one-dimensional model for the PHQ-9, PHQ-8 and GAD-7, while all PHQ and GAD scales showed good reliability. CONCLUSIONS: The PHQ and GAD have adequate measurement properties in their different versions. We present specific cut-offs for each version