Measurement Window Research Articles

A unifying view of synchronization for data assimilation in complex nonlinear networks.

Networks of nonlinear systems contain unknown parameters and dynamical degrees of freedom that may not be observable with existing instruments. From observable state variables, we want to estimate the connectivity of a model of such a network and determine the full state of the model at the termination of a temporal observation window during which measurements transfer information to a model of the network. The model state at the termination of a measurement window acts as an initial condition for predicting the future behavior of the network. This allows the validation (or invalidation) of the model as a representation of the dynamical processes producing the observations. Once the model has been tested against new data, it may be utilized as a predictor of responses to innovative stimuli or forcing. We describe a general framework for the tasks involved in the "inverse" problem of determining properties of a model built to represent measured output from physical, biological, or other processes when the measurements are noisy, the model has errors, and the state of the model is unknown when measurements begin. This framework is called statistical data assimilation and is the best one can do in estimating model properties through the use of the conditional probability distributions of the model state variables, conditioned on observations. There is a very broad arena of applications of the methods described. These include numerical weather prediction, properties of nonlinear electrical circuitry, and determining the biophysical properties of functional networks of neurons. Illustrative examples will be given of (1) estimating the connectivity among neurons with known dynamics in a network of unknown connectivity, and (2) estimating the biophysical properties of individual neurons in vitro taken from a functional network underlying vocalization in songbirds.

The Selection of Sample Period and Measurement Window for VaR

The Selection of Sample Period and Measurement Window for VaR

Age-by-Emotion Interactions in Memory Retrieval Processes: An Event-Related Potential Study.

Although research has identified age-by-emotion interactions in memory performance and in neural recruitment during retrieval, it remains unclear which retrieval processes are affected. The temporal resolution of event-related potentials (ERPs) provides a way to examine different component processes that operate during retrieval. In the present study, younger and older adults encoded neutral and emotional images paired with neutral titles. ERPs were assessed during a recognition memory task in which participants viewed neutral titles and indicated whether each had been presented during encoding. An age-related posterior-to-anterior shift began in a time window typically associated with recollection-related processes (500-800 ms) while an age-by-emotion interaction occurred only during a later measurement window (800-1,200 ms). These findings suggest an effect of age on mechanisms supporting retrieval of episodic content, prior to post-retrieval processing. The potential relations to different types of detail retrieval are discussed. Further, the later age-by-emotion interactions suggest that age influences the effect of emotion on post-retrieval processes, specifically.

Self-normalized inverse photopyroelectric technique with viscous front window for thermal effusivity measurements in liquids

In this paper, the front detection (also called inverse configuration) photopyroelectric method for thermal effusivity measurement in liquids is improved by adding a viscous liquid to the front face of the pyroelectric sensor, on which the intensity modulated excitation light beam impinges, while the sample is attached to the rear side of the sensor. This viscous liquid will act as an optical transparent window. This configuration avoids problems related with the piezoelectric contribution to the photopyroelectric signal at high modulation frequencies that can be present in conventional approaches due to thermoelastic waves generated in the heated sample or by thermally induced deformations of the detector material itself. The theoretical and experimental principles behind the proposed method are presented and its usefulness is demonstrated with measurements on test samples.

Optimal base frequency estimation of an electrical signal based on Prony’s estimator and a FIR filter

In the frequency domain modeling of power supplying networks, it is usually necessary to determine the frequency spectrum of the currents flowing through the nonlinear devices (Arrillaga and Watson, 2003; Das, 2015; Lewandowski and Walczak, 2014). The spectrum estimation can be done in many different ways (Lewandowski and Walczak, 2014; Łobos and Rezmer, 1997; Ray et al., 2016). In work (Lewandowski and Walczak, 2014) a spectrum estimation method has been proposed, which has better accuracy in comparison with other competitive methods like WIFTA (Window Interpolated Fourier Transform) or TDQS (Time Domain Quasi-Synchronous Sampling), while maintaining a low demand for computing power. The accuracy of this method depends on two main factors: the accuracy of the fundamental frequency estimation and the accuracy of the signal interpolation in the resampling process. For the estimation of the fundamental frequency, the method uses a first order Prony’s estimator (Łobos and Rezmer, 1997) and a band-pass FIR (Finite Impulse Response) filter.In the paper, an attempt was made to find the optimal parameters for both: the Prony’s estimator and the FIR filter. First, an analysis of the measurement window size of the Prony’s estimator and the number of the FIR filter coefficients was performed. Then, the optimization problem was defined, which is not trivial, since the Prony’s estimator is highly nonlinear and some of the parameters (the window size and the number of filter coefficients) are integers. The research allowed to determine the optimal values of the considered parameters of the frequency estimation method. Along with the results presented in Lewandowski and Walczak (2015) it is now possible to implement the spectrum estimation method from Lewandowski and Walczak (2014) using the optimal set of parameters.

Full-waveform inversion of triplicated data using a normalized-correlation-coefficient-based misfit function

Summary In seismic full-waveform inversion (FWI), the choice of misfit function determines what information in data is used and ultimately affects the resolution of the inverted images of the Earth's structure. Misfit functions based on traveltime have been successfully applied in global and regional tomographic studies. However, wave propagation through the upper mantle results in multiple phases arriving at a given receiver in a narrow time interval resulting in complicated waveforms that evolve with distance. To extract waveform information as well as traveltime, we use a misfit function based on the normalized correlation coefficient (CC). This misfit function is able to capture the waveform complexities in both phase and relative amplitude within the measurement window. It is also insensitive to absolute amplitude differences between modeled and recorded data, which avoids problems due to uncertainties in source magnitude, radiation pattern, receiver site effects or even miscalibrated instruments. These features make the misfit function based on normalized CC a good candidate to achieve high-resolution images of complex geological structures when interfering phases coexist in the measurement window, such as triplication waveforms. From synthetic tests, we show the advantages of this misfit function over the cross-correlation traveltime misfit function. Preliminary inversion of data from an earthquake in Northeast China images a sharper and stronger amplitude slab stagnant in the middle of the transition zone than FWI of cross-correlation traveltime.

Urine assay for tenofovir to monitor adherence in real time to tenofovir disoproxil fumarate/emtricitabine as pre-exposure prophylaxis.

Tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) is approved for pre-exposure prophylaxis (PrEP) against HIV infection. Adherence is critical for the success of PrEP, but current adherence measurements are inadequate for real-time adherence monitoring. We developed and validated a urine assay to measure tenofovir (TFV) to objectively monitor adherence to PrEP. We developed a urine assay using high-performance liquid chromatography coupled to tandem mass spectrometry with high sensitivity/specificity for TFV that allowed us to determine TFV concentrations in log10 categories between 0 and 10 000 ng/mL. We validated the assay in three cohorts: (1) HIV-positive subjects with undetectable viral loads on a TDF/FTC-based regimen, (2) healthy HIV-negative subjects who received a single dose of TDF/FTC, and (3) HIV-negative subjects receiving daily TDF/FTC as PrEP for 24 weeks. The urine assay detected TFV with greater sensitivity than plasma-based measures and with a window of measurements within 7 days of the last TDF/FTC dose. Based on the urine log-linear clearance after the last dose and its concordance with all detectable plasma levels, a urine TFV concentration > 1000 ng/mL was identified as highly predictive of the presence of TFV in plasma at > 10 ng/mL. The urine assay was able to distinguish high and low adherence patterns within the last 48 h (> 1000 ng/mL versus 10-1000 ng/mL), as well as nonadherence (< 10 ng/mL) extended over at least 1 week prior to measurement. We provide proof of concept that a semiquantitative urine assay measuring levels of TFV could be further developed into a point-of-care test and be a useful tool to monitor adherence to PrEP.

58 Measuring pyloric function using the functional lumen imaging probe

Background Manometric studies are known to be inadequate in evaluating tone and opening patterns of digestive sphincters. The functional lumen imaging probe (FLIP) evolved as an important tool in evaluating sphincteric regions in the gastrointestinal tract. Aim To evaluate the potential for this technique in a pilot study on a human volunteer to 1. Evaluate the efficiency and efficacy of placing and measuring with the probe endoscopically. 2. Demonstrate if the shape and function of the pylorus could be measured using this device. 3. Evaluate the effect of the administration of a pro-kenetic drug on the function of the pylorus. Method One subject volunteered for the procedure as the probe is already approved for diagnostic use in the gastrointestinal tract. The EndoFLIP system (Crospon, Galway, Ireland) was set up as previously described using probe model EF-353. An Olympus therapeutic endoscope was inserted as per normal upper gastrointestinal investigation. The probe was inserted into the endoscope biopsy channel and positioned straddling the pylorus. Distension measurements were made with probe volumes of 20 ml, 30 ml and 40 ml before and after the administration of 10 mg of metoclopramide (Primperan). Results Activity dramatically changed in the pylorus after Primperan. The narrowest region the sphincter measured using the minimum cross sectional (CSAmin) area was relatively inactive and stable before the drug but after the CSAmin varied significantly during the 20 s measurement window, indicating changes in activity. Conclusions The FLIP system can successfully measure distensibility in the pylorus and these measurements may be useful in determining proper function in the region.

A noninvasive online system for biomass monitoring in shaker flasks using backward scattered light

This paper presents a noninvasive optical sensor system for monitoring cell growth in shaker flasks commonly used in biological laboratories. The system uses an open-source microprocessor board to monitor concentration of Escherichia coli host cells. To allow measurement for a range of filling degrees and shaker speeds, the backscattering angle is chosen to minimize interference from surface reflections and the measurement window is synchronized to the position of the shaker flask. A nonlinear calibration model of scattered light can predict offline optical density with a mean relative error of 5.2%, an accuracy which is comparable to the classical offline method and sufficient for biotechnology applications.

Experimental study on heat transfer enhancement of wavy finned flat tubes by water spray cooling

High condensing pressure of air cooling condenser (ACC) at high environmental temperature in summer is a common problem of air-cooling power generating units. The wavy finned flat tube bundle is the key element of ACC. Experiments on heat transfer enhancement of wavy finned flat tube bundle by water spray cooling was carried out by wind tunnel with a visualized window for temperature distribution measurement of fin surface. The mechanisms of heat transfer enhancement, including that of the cooling of air due to upstream droplets evaporation and the evaporation of water film formed by droplets impacting on the finned tubes, were investigated, respectively. The cooling efficiencies for different inlet air velocities were required. While the air flow Reynolds number ranges from 210 to 680, the experimental correlations of flow and heat transfer were obtained. As compared to the case without spray, the Nusselt numbers of three water flow rates are increased by 48%, 56% and 68% on average, respectively. The respective contributions of both pre-cooling and water film evaporation were evaluated, which were almost equal as the Reynolds number is about 500. The results can benefit the optimization of spray cooling technique used in air cooling condenser.

Using simulation to aid trial design: Ring-vaccination trials.

BackgroundThe 2014–6 West African Ebola epidemic highlights the need for rigorous, rapid clinical trial methods for vaccines. A challenge for trial design is making sample size calculations based on incidence within the trial, total vaccine effect, and intracluster correlation, when these parameters are uncertain in the presence of indirect effects of vaccination.Methods and findingsWe present a stochastic, compartmental model for a ring vaccination trial. After identification of an index case, a ring of contacts is recruited and either vaccinated immediately or after 21 days. The primary outcome of the trial is total vaccine effect, counting cases only from a pre-specified window in which the immediate arm is assumed to be fully protected and the delayed arm is not protected. Simulation results are used to calculate necessary sample size and estimated vaccine effect. Under baseline assumptions about vaccine properties, monthly incidence in unvaccinated rings and trial design, a standard sample-size calculation neglecting dynamic effects estimated that 7,100 participants would be needed to achieve 80% power to detect a difference in attack rate between arms, while incorporating dynamic considerations in the model increased the estimate to 8,900. This approach replaces assumptions about parameters at the ring level with assumptions about disease dynamics and vaccine characteristics at the individual level, so within this framework we were able to describe the sensitivity of the trial power and estimated effect to various parameters. We found that both of these quantities are sensitive to properties of the vaccine, to setting-specific parameters over which investigators have little control, and to parameters that are determined by the study design.ConclusionsIncorporating simulation into the trial design process can improve robustness of sample size calculations. For this specific trial design, vaccine effectiveness depends on properties of the ring vaccination design and on the measurement window, as well as the epidemiologic setting.

Comparison of PIV Experiment and Numerical Simulation on the Velocity Distribution of Intermediate Pressure Jets with Different Nozzle Parameters

AbstractThe need for a reliable research method of the external flow field has increased with the more widespread use of intermediate pressure jets. The experimental method and numerical simulation method were investigated, using the particle image velocimetry (PIV) technique and the volume of fluid‐level set (VOF‐level set) method. Both methods performed well on nozzles with different geometric parameters at distances close to the nozzle and further away from it. With reference to the different measurement windows, the velocities in vertical profiles along the x‐axis, the change of maximum jet velocities and the break‐up length ranges of jet flows were obtained. The two methods authenticate each other, and the results indicate that the maximum velocities of jets decrease and the distribution widths of velocity field also increase with increase in distance away from the nozzles. The PIV and simulation gave similar results at different distances from the nozzle, and the experimental values were slightly higher than the simulation values due to the pressure fluctuation with an error of less than 8%. The break‐up length of jets increases with pressures in situations where the experimental values were lower than the simulation values due to the effect of air. The experimental data from PIV agreed well with the simulation results. Therefore, the accuracy and reliability of the PIV experiment and the CFD (Computational Fluid Dynamics) result simulation were both validated. Copyright © 2017 John Wiley &amp; Sons, Ltd.

Hydrogen Abstraction from Hydrocarbons by NH2.

This contribution investigates thermokinetic parameters of bimolecular gas-phase reactions involving the amine (NH2) radical and a large number of saturated and unsaturated hydrocarbons. These reactions play an important role in combustion and pyrolysis of nitrogen-rich fuels, most notably biomass. Computations performed at the CBS-QB3 level and based on the conventional transition-state theory yield potential-energy surfaces and reaction rate constants, accounting for tunnelling effects and the presence of hindered rotors. In an analogy to other H abstraction systems, we demonstrate only a small influence of variational effects on the rate constants for selected reaction. The studied reactions cover the abstraction of hydrogen atoms by the NH2 radical from the C-H bonds in C1-C4 species, and four C5 hydrocarbons of 2-methylbutane, 2-methyl-1-butene, 3-methyl-1-butene, 3-methyl-2-butene, and 3-methyl-1-butyne. For the abstraction of H from methane, in the temperature windows 300-500 and 1600-2000 K, the calculated reaction rate constants concur with the available experimental measurements, i.e., kcalculated/kexperimetal = 0.3-2.5 and 1.1-1.4, and the previous theoretical estimates. Abstraction of H atom from ethane attains the ratio of kcalculated/kexperimetal equal to 0.10-1.2 and 1.3-1.5 over the temperature windows of available experimental measurements, i.e., 300-900 K and 1500-2000 K, respectively. For the remaining alkanes (propane and n-butane), the average kexperimental/kcalculated ratio remains 2.6 and 1.3 over the temperature range of experimental data. Also, comparing the calculated standard enthalpy of reaction (ΔrH°298) with the available experimental measurements for alkanes, we found the mean unsigned error of computations as 3.7 kJ mol-1. This agreement provides an accuracy benchmark of our methodology, affording the estimation of the unreported kinetic parameters for H abstractions from alkenes and alkynes. On the basis of the Evans-Polanyi plots, calculated bond dissociation enthalpies (BDHs) correlate linearly with the standard enthalpy of activation (Δ⧧H°298), allowing estimation of the enthalpy barrier for reaction of NH2 with other hydrocarbons in future work. Finally, we develop six sets of the generalized Arrhenius rate parameters for H abstractions from different C-H bond types. These parameters extend the application of the present results to any noncyclic hydrocarbon interacting with the NH2 radical.

Hong-Ou-Mandel interference between two independent all-fiber multiplexed photon sources

Interference between independent photon sources is the key technique to realize complex quantum systems for more sophisticated applications such as multi-photon entanglement generation and quantum teleportation. Here, we report Hong-Ou-Mandel interference (HOMI) between two independent 1.55 m all-fiber photon pair sources over two 100 GHz dense wave division multiplexing (DWDM) channels, whose visibility reaches 53.2%8.4% (82.9%5.3%) without (with) back ground counts subtracted. In addition, we theoretically describe in detail the single photon spectral purity of the photon source generated in dispersion shifted fiber (DSF), simulate the influences of the pulse width and filter bandwidth on the purity, and obtain the optimized condition. The optimized pump pulse width is 8 ps and filter bandwidth is about 40 GHz or less. A home-made 1550.1 nm mode-locked fiber laser source, whose pulse width and repetition rate are 25 ps and 27.9 MHz respectively, acts as a pump of photon source. A tunable attenuator is used to adjust the pump power of the photon source, and the broad band background fluorescence photons are filtered out by cascade 100 GHz DWDM filters. The clean pump beam is divided into two equal parts by the 50 : 50 optical coupler to pump two 300 m DSFs (cooled by liquid nitrogen) to generate independent photon sources. Then the strong pump beam and noise photon from Raman scattering in orthogonal polarization are removed by 2 groups of 200 GHz DWDM filters and fiber polarization rotator and polarizer. Then two 100 GHz DWDMs are used for separating photons at correlated channel pairs. The relative delay between the two independent photons is adjusted by tunable fiber delay line. Photons from the same channels are combined in a second beam splitter for interference, and the other two photons are used as trigger signals. The two triggered photons are detected by two free running InGaAs avalanched single photon detectors (APD1, APD4, ID Quanta, ID220, 20% detection efficiency, 3 s dead time, dark count rate 4k cps), and the outputs of detectors APD1 and APD4 are used to trigger two single-photon detectors running in the gated mode (APD2, APD3, Qasky, Hefei, China, 100 MHz, free gating single photon detectors, 20% detection efficiency, dark count probability 410-5 per gate) for twophoton coincidence measurement. Detection output signals from APD2 and APD3 are sent to our coincidence count device (Pico quanta, TimeHarp 260, 1.6 ns coincidence window) for four-photon coincidence measurement. Before measuring the HOMI, we obtain a maximum-coincidence-to-accidental-coincidence ratio (CAR) of 131 by cooling the fiber in liquid nitrogen when the pump power is 23 W. There are a few remarks we want to point out.Firstly, the photon sources are not operated at the optimized pump pulse width for pure single photon generation, but narrow band 100 GHz filters are used in the experiments to increase the purity of the sources. Secondly, single photon detectors used in our experiment have lower detection efficiency and much higher dark counts than nano-wire single photon detectors, if we have high-performance nano-wire single photon detector, experimental results will be greatly improved due to the four-fold coincidences and dark coincidences scaling quadruplicate with the detection efficiency and dark count probability of a single detector. Thirdly, we use relatively high pump power for each DSF (0.12 mW) to reduce measurement time for photon coincidence, which will lead to a very poor raw visibility certainly. Finally, though only a 100 GHz channel pair is used in our experiment, we can use other channels for multiplexing such interference processes to improve the channel capacity in future quantum communication tasks theoretically. Our study shows greatly promising integrated optical elements for future scalable quantum information processing.

Acoustic radiation force impulse imaging of kidneys - a phantom study.

Aim of the studySince there have been only few works reporting the diagnosis of kidneys using Acoustic Radiation Force Impulse technique and those works do not provide consistent results of shear wave velocity measurements in renal tissue, we have decided to use kidney phantoms with known properties to examine the reliability of the method itself in a controlled setup similar to kidneys examination.Materials and methodsFour gelatin-based phantoms imitating different clinical situations were manufactured – two with thick and two with thin renal cortex, each type at a depth similar to a normal-weight or overweight patient. For each phantom, a series of interest points was chosen and for each point 20 Shear Wave Velocity measurements were taken using the build-in Virtual Touch Tissue Quantification™ tool in a Siemens Acuson S2000 ultrasound scanner equipped with a 6C1 HD Transducer (Siemens Mountainview, USA).ResultsMean Shear Wave Velocity values obtained for all the examined points ranged from 2.445 to 3.941 m/s, with standard deviation exceeding 0.1 in only one case out of 29 points, but differing significantly between all points.ConclusionsThe obtained results indicate that the method is highly reliable as long as the measurement volume contains a uniform tissue region. If the measurement window covers a region with different properties even partially, the obtained results are affected. The variance of measured values on the other hand is not affected by the said non-uniformity of material under examination. Furthermore, the variance of measured values does not show a clear dependency on the depth at which the shear wave velocities are measured.

Pore scale rock typing and upscaling

Rock-typing is an important part for micro pore scale flow simulation and macro scale reservoir simulation. It is the linkage between pore geometries and fluid flow properties. Recent research advances on pore scale flow simulation enable rock properties to be calculated based on the digital images. But the calculation results doesn’t reflect the properties of whole rock sample. Therefore a suitable upscaling method is needed. In this study we first illustrate three different rock types: depositional rock type, petrographic rock type and hydraulic rock type. Depositional rock type is defined within the context of the large-scale geologic framework and represent those original rock properties present at deposition. Petrographic rock type is also described in the context of the geological framework established from the depositional rock types, but is based on a pore-scale microscopic imaging. Hydraulic rock types is also quantified on the pore scale but represent the physical rock flow and storage properties as controlled by the pore structure. Then we introduce a work flow process that accurately solves the problem of rock typing and upscaling. The reservoir rock is a thin-bedded sandstone from an aeolian environment. For petrographic rock typing, we suppose thin-bedded rock sample as a layer system and define a measurement window moving along the z -axis of the core with Δ z =1 voxel, perpendicular to the bedding direction. Minkowski functions namely total volume, surface area, integral of mean curvature, and integral of Gaussian curvature, are calculated based on the measure windows and kmeans clustering is applied to detect layer interface. Furthermore, the integration of spatial interpolation and kmeans clustering is proved to detect the dipping interface successfully. The classification results match well with corresponding properties and stratigraphic pitch-out can be found, which reflects the aeolian process, e.g., the activity of the winds to enable sediment transport. For hydraulic rock typing, the size, geometry, and distribution of pore throats, as determined by capillary pressure measurements, control the magnitude of porosity and permeability for a given rock. Therefore dynamic geometrical properties during the physical rock flow should be considered and we use percolation test data which includes critical diameter and Minkowski functions. All of these data are calculated based on the pore throats, which the fluid flows on it. The key to successful and efficient characterization is to exploit natural scales. Values and variability of each property are function of scale due to heterogeneities. Therefore, representative elementary volumes should be selected suitably to stabilize the data measurements. We first choose different sizes of subsample and measure corresponding percolation test data, permeability and effective conductivity. After selecting suitable representative elementary volumes, bottom blocks of subsamples are used for unsupervised Gaussian mixture model clustering and top blocks of subsamples are used for supervised Gaussian mixture model clustering based on the calculated centroid which means the mean value and covariance matrix of the percolation test data for each rock type in bottom blocks. The results demonstrate that different rock types are well separated with each other and match well with the corresponding geometrical properties and petrophysical properties. Three formulas which are based on layer system, undulating surfaces and hydraulic rock typing results, are developed to do upscaling. Local permeabilities and effective conductivities are computed to predict whole rock sample’s permeabilities and effective conductivities. The results indicate that upscaling formula based on the hydraulic rock typing results is most accurate.

Regional energy efficiency and its determinants in China during 2001–2010: a slacks-based measure and spatial econometric analysis

Carbon dioxide (CO2) emissions are largely driven by fossil fuels. To reduce CO2 emissions in China, it is important to determine influential factors of energy efficiency. This paper introduces a slacks-based measure window analysis approach to evaluate regional dynamic energy efficiency during 2001–2010, and then explores energy efficiency determinants by considering spatial effects, which is conducted based on spatial econometric models. The empirical results show that there exist evident spatial correlations between regional energy efficiencies in China. We find that, there exist evident disparities in cumulative effects of energy efficiency among the eastern, central and western areas. Interestingly, significant energy efficiency spatial spillovers can be clearly found between regions within the western area and across the eastern and western areas. It is found that, energy structure, energy price, railway transportation development and R&D stock are significant at national level. However, energy structure and railway transportation development are insignificant in the central and western areas, while energy price and R&D stock are insignificant in the eastern and central areas, respectively. Industrial structure and urbanization level are found to be insignificant at national level, but industrial structure is significant in the eastern and western areas, and urbanization level is significant in the central and western areas. Surprisingly, industrial structure and urbanization level are found to have positive impacts on energy efficiency in the western area. In addition to regional disparities and local conditions, policies making should take efficiency spatial spillovers into consideration. Several interesting policy implications are achieved.

Validación de la Escala de Parentalidad Positiva (EPP) para evaluar programas presenciales y online de apoyo parental || Validation of the Positive Parenting Scale (PPS) for evaluating face-to-face and online parenting support programs

Como continuación del estudio donde se presentó la Escala de Apoyo Parental Online (EAPO), como parte de la evaluación del programa “Educar en Positivo” (http://educarenpositivo.es), el presente estudio describe la validación de una nueva escala para evaluar los principios de la parentalidad positiva en usuarios de programas presenciales y online. Para la validación de la Escala de Parentalidad Positiva (EPP) se contó con 323 padres y madres españoles y latinoamericanos, registrados en dicho programa. Para obtener la estructura factorial de la escala, se utilizó el modelo de ecuaciones estructurales exploratorio (MESE) con rotación Oblimin y para su confirmación el método de estimación de ponderación de mínimos cuadrados ajustados por la media y varianza (WLSMW). Se realizó también una prueba de la validez discriminante de la escala por medio del análisis del área bajo la curva ROC (ABC) y su comprobación mediante un análisis multivariado de covarianza (MANCOVA). Los resultados muestran una factorización óptima en el modelo de cuatro factores: Implicación familiar, Afecto y reconocimiento, Comunicación y control del estrés y Actividades compartidas con una fiabilidad adecuada. Asimismo, se demostró la capacidad discriminativa de la escala en función del perfil de experiencia y uso educativo de Internet, una vez controlada la posible influencia del nivel educativo de los participantes. La escala muestra unas propiedades psicométricas adecuadas y su contenido recoge los aspectos clave del ejercicio de la parentalidad positiva, lo que resulta muy útil para evaluar la efectividad de los programas basados en dicho enfoque.

Atmospheric oxidation and carbon contamination of silver and its effect on surface-enhanced Raman spectroscopy (SERS).

Surface-enhanced Raman spectroscopy (SERS) is considered a highly promising technology for different analytical purposes. The applications of SERS are still quite limited due its relatively poor quantitative repeatability and the fact that SERS is very sensitive to oxidation, which is a challenge especially with silver based SERS substrates. Here, the link between these phenomena is investigated by exposing silver SERS substrates to ambient laboratory air. We show that SERS intensity decreases exponentially after the exposure, which consequently leads to an increasing standard deviation (σ) in intensity. Within a five-hour measurement window, the SERS intensity already drops by 60%, while σ triples from 7% to 21%. The SERS results are supplemented by elemental analysis, which shows that oxidation and atmospheric carbon contamination coincide with the rapid SERS intensity decrease. The results emphasize how sensitive SERS is towards atmospheric contamination and how it can also reduce the measurement repeatability – even if the substrates are exposed to air just for a very short period of time.

Unsurprising Shocks: Information, Premia, and the Monetary Transmission

Central banks’ decisions are a function of forecasts of macroeconomic fundamentals. Because private sector forecasts are not bound to be equal to central banks’ forecasts, what markets label as unexpected may or may not be unanticipated by the central bank. Monetary surprises can thus incorporate anticipatory effects if market participants fail to correctly account for the systematic component of policy when they are surprised by an interest rate decision. Depending on how market participants perceive the policy decision, their economic projections and the associated risk compensations move in opposite directions, and do so at the time of the announcement. Hence, and regardless of the width of the measurement window, monetary surprises capture more than just the monetary policy shock, and their use as external instruments for identification is potentially compromised. Monetary ‘surprises’ are dependent on, and shown to be predictable by both central banks’ forecasts and past information available to market participants prior to the announcement. A New-Keynesian framework sketches the intuition. The resulting distortions in the estimated impulse response functions can be dramatic, both qualitatively and quantitatively. A new set of monetary surprises, free of anticipatory effects and unpredictable by past information, are shown to retrieve transmission coefficients to a monetary policy shock consistent with macroeconomic theory even in informationally deficient VARs.