Explosive Formation and Dynamics of Vapor Nanobubbles around a Continuously Heated Gold Nanosphere

We form sub-micrometer-sized vapor bubbles around a single laser heating gold nanoparticle in a liquid and monitor them through optical scattering of a probe laser. The fast, inertia-governed expansion is followed by a slower contraction and disappearance after some tens of nanoseconds. In a narrow range of illumination powers, bubble time traces show a clear echo signature. We attribute it to sound waves released upon the initial explosion and reflected by flat interfaces, hundreds of microns away from the particle. Echoes can trigger new explosions. A steady state of nanobubble with a vapor shell surrounding the heated nanoparticle can be reached by a proper time profile of the heating intensity. Stable nanobubbles could have original applications for light modulation and for enhanced optical-acoustic coupling in photoacoustic microscopy

Optical tracing of multiple charges in single-electron devices

Single molecules that exhibit narrow optical transitions at cryogenic temperatures can be used as local electric-field sensors. We derive the single charge sensitivity of aromatic organic dye molecules, based on first principles. Through numerical modeling, we demonstrate that by using currently available technologies it is possible to optically detect charging events in a granular network with a sensitivity better than $10^{-5}e/\sqrt{\textrm{Hz}}$ and track positions of multiple electrons, simultaneously, with nanometer spatial resolution. Our results pave the way for minimally-invasive optical inspection of electronic and spintronic nanodevices and building hybrid optoelectronic interfaces that function at both single-photon and single-electron levels.Comment: 7 pages, submitted to Physical Revie

A Common-Path Interferometer for Time-Resolved and Shot-Noise-Limited Detection of Single Nanoparticles

We give a detailed description of a novel method for time-resolved experiments on single non-luminescent nanoparticles. The method is based on the combination of pump-probe spectroscopy and a common-path interferometer. In our interferometer, probe and reference arms are separated in time and polarization by a birefringent crystal. The interferometer, fully described by an analytical model, allows us to separately detect the real and imaginary contributions to the signal. We demonstrate the possibilities of the setup by time-resolved detection of single gold nanoparticles as small as 10 nm in diameter, and of acoustic oscillations of particles larger than 40 nm in diameter

Muscle Dysmorphia: Predictive and protective factors in adolescents

 The Muscle Dysmorphia (MD) is a subcategory of body dysmorphic disorder in which subjects develop a pathological concern for their musculature. The population at risk that suffers from, or can develop MD, prevails in terms of age of appearance in subjects between 16 to 35 years; and it is more frequent in men. This study aimed to determine which variables of the personality, gender identity and passion (harmonious or obsessive) allow to predict MD in adolescents through the Adonis Complex (AC) Scale. A cross-sectional study was conducted on 506 subjects between 16 and 21 years (M=18.20; SD=1.72). The higher correlation was between AC and Emotional Control in men, and impulse control in women. Then a binary logistic regression analysis was performed and model yielded R2=.176 (X2=47.95 (16) <.001) and classified correctly in 88.5% of cases. Results of the analysis showed that harmonious passion (β=-.028, p=.046) and emotional control (β=-.616, p=.002) are protective variables while obsessive passion (β =.065, p=.013) and scrupulosity (β =.344, p=.046) were risk factors. The results show the importance of performing interventions aimed at the prevention of DM, starting from the relevance of working emotional control and harmonious passion in this stage of life and training. Keywords: Vigorexia, Adonis Complex, Body Dimorphic Disorder.    La Dismorfia Muscular (DM) es una subcategoría del trastorno dismórfico corporal en el que los sujetos desarrollan una preocupación patológica por su musculatura. La población en riesgo que sufre o puede desarrollar DM prevalece en términos de edad de aparición en sujetos de entre 16 y 35 años; Y es más frecuente en los hombres. Este estudio tuvo como objetivo determinar qué variables de la personalidad, la identidad de género y la pasión (armoniosa u obsesiva) permiten predecir la DM en adolescentes a través de la Escala del Complejo de Adonis (CA). Se realizó un estudio transversal en 506 sujetos entre 16 y 21 años (M = 18.20; SD = 1.72). La mayor correlación fue entre CA y Control emocional en hombres y control de impulsos en mujeres. Luego se realizó un análisis de regresión logística binaria y el modelo produjo R2 = .176 (X2 = 47.95 (16) <.001) y se clasificó correctamente en el 88.5% de los casos. Los resultados del análisis mostraron que la pasión armoniosa (β = -. 028, p = .046) y el control emocional (β = - .616, p = .002) son variables protectoras mientras que la pasión obsesiva (β = .065, p =. 013) y escrupulosidad (β = .344, p = .046) fueron factores de riesgo. Los resultados muestran la importancia de realizar intervenciones dirigidas a la prevención de la DM, a partir de la relevancia del control emocional de trabajo y la pasión armoniosa en esta etapa de la vida y la formación.             Palabras clave: Vigorexia. Complejo de Adonis, Trastorno Dismorfico Corporal.    A dismorfia muscular (DM) é uma subcategoria do transtorno dismórfico corporal em que os indivíduos desenvolvem uma preocupação patológica pela sua musculatura. A população em risco que sofre ou pode desenvolver DM prevalece em termos de idade de aparecimento em indivíduos entre 16 a 35 anos; e é mais frequente nos homens. Este estudo teve como objetivo determinar quais variáveis ​​da personalidade, identidade de gênero e paixão (harmoniosa ou obsessiva) permitem prever a DM em adolescentes por meio da Escala do Complexo de Adônis (CA). Um estudo transversal foi realizado em 506 sujeitos entre 16 e 21 anos (M = 18,20; SD = 1,72). A maior correlação foi entre CA e Controle Emocional em homens e controle de impulso em mulheres. Em seguida, foi realizada uma análise de regressão logística binária e o modelo rendeu R2 = .176 (X2 = 47,95 (16) <0,001) e classificado corretamente em 88,5% dos casos. Os resultados da análise mostraram que a paixão harmoniosa (β = -. 028, p =, 046) e controle emocional (β = -. 616, p = 0,002) são variáveis ​​de proteção, enquanto paixão obsessiva (β = .065, p =. 013) e escrupulosidade (β =, 344, p =, 046) foram fatores de risco. Os resultados mostram a importância da realização de intervenções voltadas à prevenção do DM, a partir da relevância do controle emocional do trabalho e da paixão harmoniosa nesta etapa da vida e do treinamento.             Palavras chave:  Vigorexia Complexo Adonis, Transtorno Corporal Desmoronar

Study on conduction mechanismes of mediun voltage cable XLPE insulation in the melting range of temperatures.

D’ençà que el polietilè reticulat (XLPE) es va començar a utilitzar com aïllament elèctric per cables de subministrament elèctric, s’han destinat molts esforços a l’estudi de les propietats dielèctriques del polietilè i l’efecte que la càrrega d’espai té sobre el seu comportament. En aquest sentit, les corrents de despolarització estimulades tèrmicament (TSDC) s’han utilitzat extensament per estudiar les relaxacions de càrrega d’espai. Aquesta tècnica ha demostrat tenir prou resolució per distingir diferències en aïllaments de XLPE amb composicions o processos de fabricació diferents. En aquesta tesi, els mecanismes de conducció dels aïllaments XLPE de cables de mitjana tensió (MV) han estat estudiats per TSDC i diverses tècniques complementàries, com l’anàlisi dinàmica elèctrica (DEA), les corrents d’absorció/resorció (ARC), el pols electroacústic (PEA) i les corrents de despolarització isotèrmiques (IDC). Altres tècniques, com l’espectroscòpia d’infrarojos (FTIR) o la difracció de raigs X, han estat també utilitzades per caracteritzar el material. S’han obtingut espectres TSDC per diferents mostres de cable, les quals en condicions de servei treballen en un rang de tensió AC de 12 a 20kV i a temperatures al voltant dels 90ºC. D’altra banda, s’han realitzat mesures de la conductivitat per ARC i DEA en mostres de cable, en cilindres de XLPE i en films. Les mesures s’han dut a terme a temperatures pertanyents al rang de fusió del XLPE (50–110ºC), en mostres sotmeses a aquestes temperatures durant diferents períodes de temps. Els resultats mostren diferències importants entre el comportament de les propietats conductives de les mostres de cable amb pantalles semiconductores (SC) i sense (cilindres de XLPE). El comportament observat ha estat explicat mitjançant la coexistència de dos mecanismes de conducció. La difusió d’impureses des de les pantalles SC determina el comportament d’una d’aquestes contribucions a mig i llarg termini. Els resultats obtinguts per FTIR són consistents amb aquest model. Respecte la microestructura, tant les mesures DSC com la difracció per raigs X mostren que existeixen processos de recristal•lització quan les mostres són sotmeses a temperatures ubicades dins del rang de fusió. Els electrets formats mitjançant el mètode de la polarització per finestres (WP) mostren una descàrrega TSDC amb un ample pic heteropolar en el rang de fusió, amb el màxim al voltant dels 105ºC. En treballs previs, aquest pic es va associar a la fusió de la fracció cristal•lina. Tanmateix, en lloc de decréixer quan la temperatura de polarització augmenta, el pic presenta una temperatura de polarització òptima al voltant de 90-95ºC. Aquest comportament ha estat explicat tenint en compte els processos de recristal•lització que es produeixen quan el material es polaritza isotèrmicament. Durant la recristal•lització, una nova fracció cristal•lina creix en un estat polaritzat degut el camp aplicat, i origina una corrent de despolarització quan es fon durant la mesura TSDC. Amb l’objectiu de determinar l’origen d’altres pics que apareixen en l’espectre TSDC del XLPE, s’han emprat les IDC com a tècnica complementària. Les corrents IDC obtingudes de mostres no tractades es poden representar com la combinació de dues contribucions diferenciades: un terme que és una funció potencial del temps i un d’exponencial. La segona relaxació es correspon amb un pic TSDC que apareix a 95ºC. D’aquesta manera s’ha pogut determinar l’origen dipolar del pic. Finalment, mitjançant la tècnica PEA s’ha obtingut la distribució de la càrrega d’espai en mostres polaritzades que havien estat sotmeses a diferents tractaments tèrmics. S’ha observat un comportament transitori tant per PEA com per TSDC. Tanmateix no s’ha pogut establir cap relació directa entre les descàrregues TSDC i mesures PEA. En conseqüència, s’ha proposat una explicació per les corbes TSDC que considera mecanismes que no són detectables en els perfils de càrrega obtinguts per PEASince cross-linked polyethylene (XLPE) started to be used as electrical insulation for power cables, much research has been focused on polyethylene dielectric properties and the effect of the space charge on its behavior. In this sense, thermally stimulated depolarization currents (TSDC) have been widely used to study space charge relaxation. This technique has proved to have enough resolution to determine differences in charge trapping properties among XLPE insulations with different composition and manufacturing processes. In this thesis work, the conduction mechanisms of medium voltage (MV) cable XLPE insulation have been studied by TSDC and several complementary techniques, such as dynamic electrical analysis (DEA), absorption/resorption currents (ARC), pulsed electroacoustic (PEA) and isothermal depolarization currents (IDC). Other techniques, like Fourier transform infrared (FTIR) spectroscopy or X-ray diffractometry, have been used to characterize the material. TSDC spectra have been obtained for different cable samples, which in service conditions work under AC voltages ranging from 12 to 20kV and at temperatures around 90ºC. On the other hand, conductivity measurements by ARC and DEA have been performed in cable samples and in XLPE cylinders, as well as XLPE films. Measurements have been carried out at temperatures within the melting temperature range of XLPE (50–110ºC) on samples annealed at such temperatures during several annealing times. Results show significant differences in the behavior of the conductive properties of XLPE cable samples with semiconducting (SC) screens and without them (XLPE cylinders). The observed behavior has been explained by the coexistence of two conduction mechanisms. Diffusion of impurities from SC screens determines the medium and long-term behavior of one of these contributions and, hence, of cable conductivity. FTIR results are consistent with this model. With respect to microstructure, DSC and X-ray diffractometry results show that recrystallization processes exist when samples are annealed in the melting range of temperatures. Electrets formed by means of the windowing polarization method (WP) showed a TSDC discharge with a wide heteropolar peak in the melting temperature range, and with the maximum at about 105ºC. This peak was associated with the melting of the crystalline fraction in previous works. However, in spite of decreasing with the temperature of polarization, an optimal polarization temperature around 90–95ºC is found. This behavior has been explained by taking into account recrystallization processes when the insulation is isothermally polarized. During recrystallization, the new crystalline fraction grows in a polarized state due to the applied electric field, and it causes the depolarization current when it melts during the TSDC measurement. Results obtained from different experiments are consistent with this assumption. With the aim to find out the origin of other TSDC peaks present in the spectrum of XLPE cable samples, IDC has been used as complementary technique. IDC currents obtained from as-received cable samples at temperatures close to service conditions can be considered as the combination of two different contributions: a power law current and a stretched exponential contribution. The last relaxation process has been successfully associated with with a TSDC peak found at 95ºC. By this way the dipolar origin of the peak has been determined. Finally, PEA measurements have provided the space charge distribution profiles of polarized samples with different annealings. A transient behavior has been observed in both PEA and TSDC measurements. However, no straightforward relation between TSDC discharges and space charge detected by PEA can be established. Therefore, an explanation for TSDC curves has been proposed, which considers mechanisms that are not noticeable in charge profiles obtained by PEA.Postprint (published version

Behavioral modeling for sampling receiver and baseband in Software-Defined Radio

Projecte realitzat en col.laboració amb Illinois Institute of TechnologySoftware Defined-Radio (SDR) consists of a wireless communication in which the transmitter and the receiver are controlled by means of software. Its ultimate goal is to provide a single universal radio transceiver capable of multi-mode multi-standard wireless communications. Modeling of the proper circuits and new designs aimed at SDR is necessary for further development and experimentation. It sharpens our understanding of fundamental processes, helps to make decisions and provides a guide for training exercises. Due to the lack of these models two independent and different models have been created based on new proposed designs. Each modeled design belongs to a different layer of abstraction and therefore, the tool used is different as well. The first proposed model consist of a Simulink (Matlab) file which models the discrete-time signal processing used in a Discrete-time receiver for Bluetooth Radio. The results show good performance when processing a signal that has been transmitted through a noisy channel. The signal at each step is visualized to see the individual effect of each building block. The second proposed model narrows down the topic and focuses on a Widely-tunable, Reconfigurable Analog Baseband filter, for which a Verilog-A model, by using Cadence, has been created. The outstanding feature of the filter is that its programmability is based on the duty-cycle of the input control signals. Moreover, Verilog-A modules bring the design really close to the real circuit, allowing the designer to face problems that the real circuit will present and easing the replacement of the building blocks with new ones when desired. The results for this model show a very little error within the passband of the filter that increases when the attenuation introduced for the stopband becomes higher

Explosive, oscillatory, and Leidenfrost boiling at the nanoscale

We investigate the different boiling r\'egimes around a single continuously laser-heated 80 nm gold nanoparticle and draw parallels to the classical picture of boiling. Initially, nanoscale boiling takes the form of transient, inertia-driven, unsustainable boiling events characteristic of a nanoscale boiling crisis. At higher heating power, nanoscale boiling is continuous, with a vapor film being sustained during heating for at least up to 20 $\mu$s. Only at high heating powers does a substantial stable vapour nanobubble form. At intermediate heating powers, unstable boiling sometimes takes the form of remarkably stable nanobubble oscillations with frequencies between 40 MHz and 60 MHz; frequencies that are consistent with the relevant size scales according to the Rayleigh-Plesset model of bubble oscillation, though how applicable that model is to plasmonic vapor nanobubbles is not clear