Multidimensional Techniques Research Articles

Determination of Cadmium (II) in Aqueous Solutions by In Situ MID-FTIR-PLS Analysis Using a Polymer Inclusion Membrane-Based Sensor: First Considerations.

Environmental monitoring is one of the most dynamically developing branches of chemical analysis. In this area, the use of multidimensional techniques and methods is encouraged to allow reliable determinations of metal ions with portable equipment for in-field applications. In this regard, this study presents, for the first time, the capabilities of a polymer inclusion membrane (PIM) sensor to perform cadmium (II) determination in aqueous solutions by in situ visible (VIS) and Mid- Fourier transform infrared spectroscopy (MID-FTIR) analyses of the polymeric films, using a partial least squares (PLS) chemometric approach. The influence of pH and metal content on cadmium (II) extraction, the characterization of its extraction in terms of the adsorption isotherm, enrichment factor and extraction equilibrium were studied. The PLS chemometric algorithm was applied to the spectral data to establish the relationship between cadmium (II) content in the membrane and the absorption spectra. Furthermore, the developed MID-FTIR method was validated through the determination of the figures of merit (accuracy, linearity, sensitivity, analytical sensitivity, minimum discernible concentration difference, mean selectivity, and limits of detection and quantitation). Results showed reliable calibration curves denoting systems’ potentiality. Comparable results were obtained in the analysis of real samples (tap, bottle, and pier water) between the new MID-FTIR-PLS PIM based-sensor and F-AAS.

Hydroperoxylated vs Dihydroxylated Lipids: Differentiation of Isomeric Cardiolipin Oxidation Products by Multidimensional Separation Techniques.

In recent years, cardiolipin (CL) oxidation products were recognized as potential markers for mitochondrial dysfunction in conjunction with age related diseases. The analysis of oxidized CL requires powerful analysis techniques due to high structural diversity. In addition, low concentrations of partly labile compounds pose a special challenge, supplemented by the occurrence of isomeric compounds, e.g., hydroperoxylated vs dihydroxylated products. Therefore, we present a hyphenated method based on liquid chromatography coupled to trapped ion mobility spectrometry (TIMS) for separation and tandem mass spectrometry (MS/MS) for structural characterization. This enables comprehensive analysis of an artificially oxidized CL extract of bovine heart. Isomeric oxidation products could be differentiated by mobility-resolved MS/MS fragmentation experiments. Our developed method could help to better understand the physiological role of oxidized CL.

Telling a Complicated Grief: A Psychodynamic Study on Mental Health Nurses’ Countertransference Reactions to Patients’ Suicidal Behavior

A key element of suicide education, training and clinical supervision is enhancing emotional awareness about mental health professionals’ countertransference reactions, as emotional responses to patients’ suicidal behavior (SB) that may be unbeneficial to care. This study aimed to explore emotional responses to patients’ SB in mental health nurses (MHNs) according to a psychodynamic perspective. Twenty-eight Italian MHNs (61% females, Mage = 52 years) were interviewed to examine their deep feelings about attempted suicides or deaths by suicide of patients with mental illness. Computer-aided thematic analysis was performed on the verbatim transcribed interviews, adopting Emotional Text Analysis (ETA) as a research framework to explore affective symbolizations underlying narratives, beyond intentional and explicitly reported contents. Some statistical multidimensional techniques were carried out, allowing th.e detection of shared symbolic domains (Cluster Analysis) and latent factors organizing the contraposition between them (Multiple Correspondence Analysis). Five symbolic domains emerged which were respectively referred to as: hyper-vigilance (21.97% of the overall textual corpus), resentment (17.86%), rationalization (34.50%), resignation (5.54%) and mourning (20.12%). Four latent factors explained the overall data variance: strive for reparation (F1), lack of control (F2), ambivalence toward care (F3) and complicated grief (F4). Some clinical recommendations were derived suggesting to balance issues of risk assessment/management and staff’s reflective practice, to work on the subjective sense of hopelessness resulting from turning against oneself the hostility evoked by patients, to consider rationalization processes and implicit beliefs leading to risk underestimation and to address some basic conflicts contributing to a complicated grief in mourning suicidal events.

1H detection of heteronuclear dipolar oscillations with water suppression in single crystal peptide and oriented protein samples

Oriented sample solid-state NMR is a complementary approach to protein structure determination with the distinct advantage that it can be applied to supramolecular assemblies, such as viruses and membrane proteins, under near-native conditions, which generally include high levels of hydration as found in living systems. Thus, in order to perform 1H detected versions of multi-dimensional experiments water suppression techniques must be integrated into the pulse sequences. For example, 1H-windowed detection of 1H-15N dipolar couplings enable multi-dimensional NMR experiments to be performed. Here we show that the addition of a solvent suppression pulse during the z-filter interval greatly improves the sensitivity of the experiments by suppressing the 1H signals from water present. This is demonstrated here with a crystal sample submerged in water and then extended to proteins. The combination of solvent-suppressed 1H detected PISEMO and the use of a strip shield-solenoid coil probe configuration provides a two-fold sensitivity enhancement in both the crystal sample and Pf1 coat protein sample compared to the 15N direct detection method. Here we also examine protein NMR line-widths and sensitivity enhancements in the context of window detected separated local field experiments for protein samples.

Seeding and Growth of β-Amyloid Aggregates upon Interaction with Neuronal Cell Membranes.

In recent years, the prevalence of amyloid neurodegenerative diseases such as Alzheimer’s disease (AD) has significantly increased in developed countries due to increased life expectancy. This amyloid disease is characterized by the presence of accumulations and deposits of β-amyloid peptide (Aβ) in neuronal tissue, leading to the formation of oligomers, fibers, and plaques. First, oligomeric intermediates that arise during the aggregation process are currently thought to be primarily responsible for cytotoxicity in cells. This work aims to provide further insights into the mechanisms of cytotoxicity by studying the interaction of Aβ aggregates with Neuro-2a (N2a) neuronal cells and the effects caused by this interaction. For this purpose, we have exploited the advantages of advanced, multidimensional fluorescence microscopy techniques to determine whether different types of Aβ are involved in higher rates of cellular toxicity, and we measured the cellular stress caused by such aggregates by using a fluorogenic intracellular biothiol sensor. Stress provoked by the peptide is evident by N2a cells generating high levels of biothiols as a defense mechanism. In our study, we demonstrate that Aβ aggregates act as seeds for aggregate growth upon interacting with the cellular membrane, which results in cell permeability and damage and induces lysis. In parallel, these damaged cells undergo a significant increase in intracellular biothiol levels.

Advanced Characterization Techniques for Overcoming Challenges of Perovskite Solar Cell Materials

AbstractIn the last 10 years, organic–inorganic hybrid perovskite solar cells have achieved unprecedented advances, to the point where they now exhibit extremely high efficiency. However, long‐term stability and areal scalability limitations impede the commercial application of perovskite materials, and appropriate diagnosistic tools have become necessary to evaluate perovskite materials. Characterization of perovskite materials is regularly misinterpretated, due to unique intrinsic and extrinsic factors: degradation from the measurement source, ion migration, phase transition, and separation. Herein, studies on perovskites are reviewed that have used advanced characterization tools to overcome characterization challenges. Cryogenic temperature assisted measurements mitigate degradation or phase transitions induced by the measurement source. In situ measurements can track the variation of perovskite materials depending on external stimuli. Spatial material properties are able to be evaluated by the use of multidimensional mapping techniques. An overview of these advanced characterization tools that can overcome the challenges associated with established tools provides the opportunity for further understanding perovskite materials and solving the remaining challenges on the road to commercialization.

New multidimensional classification scheme of altered igneous rocks from performance comparison of isometric and modified log-ratio transformations of major elements

Nomenclature in any science is of fundamental importance. From performance comparison of isometric and modified or hybrid log-ratio transformations of major elements, we present a complete multidimensional classification scheme for altered igneous rocks for High-Mg rock varieties and magma and rock types. This scheme is efficiently applicable through a computer package called Multidimensional Igneous rock Classification System (MICSys) that encapsulates four new online computer modules (HMgClaMSys_ilr, MagClaMSys_mlr, and IgRoClaMSys_mlr and a robustness evaluation module). We used a major element database of multinormally distributed 33868 samples of relatively fresh igneous rocks and compared the performance of isometric log-ratio and modified log-ratio transformations, both of which were multinormally distributed in terms of the 9 log-transformed variables as confirmed by the DOMUDaF program. The system must be trained from only fresh rocks because the prior class assignment requires an efficient scheme accepted by all, which is available only for fresh rocks. The multivariate technique of linear discriminant analysis (LDA) and canonical analysis applied to the two transformations provided the same percent success or correct classification for the respective databases. With these findings, we reinforce the recently published work on the International Union of Geological Sciences (IUGS)-consistent multidimensional classification of altered igneous rocks. The numerous tests and applications documented earlier on multidimensional classification were applied in the present work. The mathematical properties of log-ratio transformations are no longer important, provided the multidimensional technique involves the LDA and canonical analysis. MICSys available for online application at the web portal http://tlaloc.ier.unam.mx , was successfully applied to 6 new tests and 11 new applications to illustrate the usefulness of our multidimensional classification system to igneous rocks altered from post-emplacement compositional changes. Robustness of the new scheme for altered igneous rock nomenclature as compared to the conventional IUGS procedure for fresh rock nomenclature was confirmed from simulation of post-emplacement alteration of all elements in 28 different rock compositions representative of all rock types. Even greater robustness was demonstrated against analytical uncertainty propagation in 14 geochemical reference materials issued from Canada (3), France (3), Japan (5), and the USA (3). The estimation of robustness against post-emplacement changes and uncertainty propagation was facilitated by the incorporation of a fourth module in MICSys. This work, therefore, clearly shows that, for altered rocks, the new multidimensional scheme should be used, instead of the conventional classification meant for fresh rocks only.

A comparative user study of visualization techniques for cluster analysis of multidimensional data sets

This article presents an empirical user study that compares eight multidimensional projection techniques for supporting the estimation of the number of clusters, [Formula: see text], embedded in six multidimensional data sets. The selection of the techniques was based on their intended design, or use, for visually encoding data structures, that is, neighborhood relations between data points or groups of data points in a data set. Concretely, we study: the difference between the estimates of [Formula: see text] as given by participants when using different multidimensional projections; the accuracy of user estimations with respect to the number of labels in the data sets; the perceived usability of each multidimensional projection; whether user estimates disagree with [Formula: see text] values given by a set of cluster quality measures; and whether there is a difference between experienced and novice users in terms of estimates and perceived usability. The results show that: dendrograms (from Ward’s hierarchical clustering) are likely to lead to estimates of [Formula: see text] that are different from those given with other multidimensional projections, while Star Coordinates and Radial Visualizations are likely to lead to similar estimates; t-Stochastic Neighbor Embedding is likely to lead to estimates which are closer to the number of labels in a data set; cluster quality measures are likely to produce estimates which are different from those given by users using Ward and t-Stochastic Neighbor Embedding; U-Matrices and reachability plots will likely have a low perceived usability; and there is no statistically significant difference between the answers of experienced and novice users. Moreover, as data dimensionality increases, cluster quality measures are likely to produce estimates which are different from those perceived by users using any of the assessed multidimensional projections. It is also apparent that the inherent complexity of a data set, as well as the capability of each visual technique to disclose such complexity, has an influence on the perceived usability.

Evaluación de la aplicación del programa educativo para el entrenamiento de los estudiantes que participan en las Olimpiadas de Química

La educación en Cuba ha prestado gran atención al entrenamiento de los estudiantes que participan en los concursos de conocimientos y en las olimpiadas. Por esta razón, los estudiantes ganadores de la Olimpiada Nacional realizan un proceso de preparación especial, con el fin de participar en los eventos internacionales. El proceso que se desarrolla constituye una de las vías de atención al talento académico en química, pues la mayoría de ellos optan por carreras relacionadas con esta ciencia. Esto justifica el objetivo de este trabajo: evaluar el programa educativo aplicado a los estudiantes que participaron en el proceso de entrenamiento para su participación en las Olimpiadas de Conocimientos de Química, desde las esferas cognitiva-instrumental, motivacional-afectiva y psicosocial, aspectos que forman parte de una investigación realizada. Los métodos investigativos utilizados a fin de cumplir este objetivo fueron: análisis documental, análisis y síntesis, la prueba estadística, determinación del coeficiente de correlación multidimensional, técnicas y pruebas psicológicas. Como resultado se presentan las acciones a realizar para la ejecución del programa, la información obtenida luego de la aplicación de varios instrumentos y la utilización del coeficiente multidimensional en la determinación de la coherencia entre los indicadores propuestos en las tres analizadas durante la investigación.

Functional diversity metrics using kernel density n‐dimensional hypervolumes

Abstract The use of n‐dimensional hypervolumes in trait‐based ecology is rapidly increasing. By representing the functional space of a species or community as a Hutchinsonian niche, the abstract Euclidean space defined by a set of independent axes corresponding to individuals or species traits, these multidimensional techniques show great potential for the advance of functional ecology theory. In the panorama of existing methods for delineating multidimensional spaces, the r package hypervolume (Global Ecology and Biogeography, 23, 2014, 595–609) is currently the most used. However, functions for calculating the standard set of functional diversity (FD) indices—richness, divergence and regularity—have not been developed within the hypervolume framework yet. This gap is delaying its full exploitation in functional ecology, meanwhile preventing the possibility to compare its performance with that of other methods. We develop a set of functions to calculate FD indices based on n‐dimensional hypervolumes, including alpha (richness), beta (and respective components), dispersion, evenness, contribution and originality. Altogether, these indices provide a coherent framework to explore the primary mathematical components of FD within a multidimensional setting. These new functions can work either with hypervolume objects or with raw data (species presence or abundance and their traits) as input data, and are versatile in terms of input parameters and options. These functions are implemented within bat (Biodiversity Assessment Tools), an r package for biodiversity assessments. As a coherent corpus of functional indices based on a common algorithm, it opens the possibility to fully explore the strengths of the Hutchinsonian niche concept in community ecology research.

Convergence Analysis of a Trust-Region Multidimensional Filter Method for Nonlinear Complementarity Problems

For solving nonlinear complementarity problems, a new algorithm is proposed by using multidimensional filter techniques and a trust-region method. The algorithm is shown to be globally convergent under the reasonable assumptions and does not depend on any extra restoration procedure. In particular, it shows that the subproblem is a convex quadratic programming problem, which is easier to be solved. The results of numerical experiments show its efficiency.

Body oriented work with refugees

ABSTRACT This article will present personal experiences of work, generally, with traumatised people and especially traumatised refugees, using approaches from body-oriented psychotherapy. Personal experiences as a body psychotherapist are presented from two main schools: Mind-Body Medicine and some techniques from the Radix approach. Even though integrative body psychotherapy is mentioned in this article, the main discussion is presented from the first two approaches. The Mind-Body Medicine approach is presented more in detail because of clinical and practical experiences of the therapist, and other approaches are mentioned in passing in individual case material. The variety of multidimensional methods and techniques using body-oriented work with refugees is one of the essential factors for the treatment of acute trauma in group and individual settings.

An urban informatics approach to understanding residential mobility in Metro Chicago

This paper proposes that urban informatics can represent a flow of information from diverse and voluminous data into and back from the planning process. We present a proof-of-concept of how an urban informatics approach can improve public understanding of essential information in the planning process, and we propose a theoretical construct of how it can make planning processes more democratic and participatory, especially for disadvantaged groups. Specifically, this study uses a multi-dimensional spatial scan technique to discover household movement patterns in Chicago from millions of household address records between 2006 and 2015. The results locate the types of movement and displacement associated with specific places at a highly detailed spatial resolution. A user-interface is developed and proposed to enhance sharing of the information to the general public and involves diverse stakeholders in policy-making processes.

Digital scanned laser light-sheet fluorescence lifetime microscopy with wide-field time-gated imaging.

We develop a multidimensional fluorescence imaging technique by implementing a wide-field time-gated fluorescence lifetime imaging into digital scanned laser light-sheet microscopy (FLIM-DSLM) to measure 3D fluorescence lifetime distribution in mesoscopic specimens with high resolution. This is achieved by acquiring a series of time-gated images at different relative time delays with respect of excitation pulses at different depths. The lifetime is determined for each voxel by iteratively fitting to single exponential decay. The performance of the developed system is evaluated with the measurements of a lifetime reference Rhodamine 6G solution and a subresolution fluorescent bead phantom. We also demonstrate the application performances of this system to ex vivo and in vivo imaging of Tg(kdrl:EGFP) transgenic zebrafish embryos, illustrating the lifetime differences between the GFP signal and the autofluorescence signal. The results show that FLIM-DSLM can be used for sample size up to a few millimetres and can be utilised as a powerful and robust method for biomedical research, for example as a readout of protein-protein interactions via Förster resonance energy transfer.

Atomic fluctuations in electronic materials revealed by dephasing

The microscopic origin and timescale of the fluctuations of the energies of electronic states has a significant impact on the properties of interest of electronic materials, with implication in fields ranging from photovoltaic devices to quantum information processing. Spectroscopic investigations of coherent dynamics provide a direct measurement of electronic fluctuations. Modern multidimensional spectroscopy techniques allow the mapping of coherent processes along multiple time or frequency axes and thus allow unprecedented discrimination between different sources of electronic dephasing. Exploiting modern abilities in coherence mapping in both amplitude and phase, we unravel dissipative processes of electronic coherences in the model system of CdSe quantum dots (QDs). The method allows the assignment of the nature of the observed coherence as vibrational or electronic. The expected coherence maps are obtained for the coherent longitudinal optical (LO) phonon, which serves as an internal standard and confirms the sensitivity of the technique. Fast dephasing is observed between the first two exciton states, despite their shared electron state and common environment. This result is contrary to predictions of the standard effective mass model for these materials, in which the exciton levels are strongly correlated through a common size dependence. In contrast, the experiment is in agreement with ab initio molecular dynamics of a single QD. Electronic dephasing in these materials is thus dominated by the realistic electronic structure arising from fluctuations at the atomic level rather than static size distribution. The analysis of electronic dephasing thereby uniquely enables the study of electronic fluctuations in complex materials.

Resilient Cooperative Control for Networked Lagrangian Systems Against DoS Attacks.

In this article, we study the distributed resilient cooperative control problem for directed networked Lagrangian systems under denial-of-service (DoS) attacks. The DoS attacks will block the communication channels between the agents. Compared with the existing methods for the linear networked systems, the considered nonlinear networked Lagrangian systems with asymmetric channels under DoS attacks are more challenging and still not well explored. In order to solve this problem, a novel resilient cooperative control scheme is proposed by using the sampling control approach. Sufficient conditions are first derived in the absence of DoS attacks according to a multidimensional small-gain scheme. Then, in the presence of DoS attacks, the proposed resilient scheme works in a switching manner. Inspired by multidimensional small-gain techniques, the Lyapunov approach is used to analyze the closed-loop system, which enables us to establish sufficient stability conditions for the control gains in terms of the duration and frequency of the DoS attacks.

Nonlinear beamforming for enhancement of 3D prestack land seismic data

We have developed nonlinear beamforming (NLBF), a method for enhancing modern 3D prestack seismic data acquired onshore with small field arrays or single sensors in which weak reflected signals are buried beneath the strong scattered noise induced by a complex near surface. The method is based on the ideas of multidimensional stacking techniques, such as the common-reflection-surface stack and multifocusing, but it is designed specifically to improve the prestack signal-to-noise ratio of modern 3D land seismic data. Essentially, NLBF searches for coherent local events in the prestack data and then performs beamforming along the estimated surfaces. Comparing different gathers that can be extracted from modern 3D data acquired with orthogonal acquisition geometries, we determine that the cross-spread domain (CSD) is typically the most convenient and efficient. Conventional noise removal applied to modern data from small arrays or single sensors does not adequately reveal the underlying reflection signal. Instead, NLBF supplements these conventional tools and performs final aggregation of weak and still broken reflection signals, where the strength is controlled by the summation aperture. We have developed the details of the NLBF algorithm in CSD and determined the capabilities of the method on real 3D land data with the focus on enhancing reflections and early arrivals. We expect NLBF to help streamline seismic processing of modern high-channel-count and single-sensor data, leading to improved images as well as better prestack data for estimation of reservoir properties.

Emotional and symbolic components of hikikomori experience: A qualitative narrative study on social withdrawal

Hikikomori is a form of social withdrawal affecting adolescents and young adults that prevents social, school and work activities. The present study aims at expanding qualitative narrative research on such a social withdrawal from the participants’ perspective, as to detect emotional and symbolic components of the hikikomori experience. Emotional Text Analysis was conducted on the narratives of 17 Italian people (9 men, 18-39 aged), who posted their hikikomori stories via an online forum. Statistical multidimensional techniques were performed to detect some thematic domains (Cluster Analysis) and latent factors organizing the contraposition between them (Multiple Correspondence Analysis). Five clusters emerged as follows: refusal of intimacy (cluster 1), retreat to passivity (cluster 2), search for comfort (cluster 3), interpersonal distress (cluster 4), and performance anxiety (cluster 5). Then, four latent factors were identified dealing with a complex of dependency, tendency to introversion, refusal of agency, and ambivalence towards intimacy, respectively. The results provide new insights on the complexity and awareness of the affective experience of hikikomori to be integrated with the existing evidence in the literature.

Analysis of Carcinogenic Polycyclic Aromatic Hydrocarbons in the Complex Background of the Petroleum Fluorescence Using Multivariate Curve Resolution Alternating Least Square and Total Synchronous Fluorescence Spectroscopic Technique.

Multivariate curve resolution alternating least square (MCR-ALS) analysis allows the simultaneous retrieval of pure concentration and spectral profiles for each of the analysed chemical components from the composite spectrum even in the presence of unknown interferences. Total synchronous fluorescence spectroscopy (TSFS), a multidimensional fluorescence technique that describes the variation of synchronous fluorescence profile acquired as a function of increasing offset, has become a useful analytical technique. Suitably arranged TSFS data set can be easily processed using MCR-ALS and thereby a simple and sensitive analytical tool could be developed. The present work successfully used the combination of the MCR-ALS and TSFS to analyse the three carcinogenic and mutagenic polycyclic aromatic hydrocarbons (PAHs) namely Benzo[a]Pyrene, Chrysene and Pyrene in the presence of complex fluorescence background originated from petroleum product. MCR-ALS assisted TSFS can be used for the routine analyses of these carcinogenic PAHs to ensure the quality of water and other samples belonging to different part of the ecosystem.

Why Is it So Cold in Here? Explaining the Cold Temperatures Retrieved from Transmission Spectra of Exoplanet Atmospheres

Abstract Transmission spectroscopy is a powerful technique widely used to probe exoplanet terminators. Atmospheric retrievals of transmission spectra are enabling comparative studies of exoplanet atmospheres. However, the atmospheric properties inferred by retrieval techniques display a significant anomaly: most retrieved temperatures are far colder than expected. In some cases, retrieved temperatures are colder than . Here, we provide an explanation for this conundrum. We demonstrate that erroneously cold temperatures result when 1D atmospheric models are applied to spectra of planets with differing morning–evening terminator compositions. Despite providing an acceptable fit, 1D retrieval techniques artificially tune atmospheric parameters away from terminator-averaged properties. Retrieved temperature profiles are hundreds of degrees cooler and have weaker temperature gradients than reality. Retrieved abundances are mostly biased by and sometimes by , with the most extreme biases for ultra-hot Jupiters. When morning–evening compositional differences manifest for prominent opacity sources, H2O abundances retrieved by 1D models can be biased by over an order of magnitude. Finally, we demonstrate that these biases provide an explanation for the cold retrieved temperatures reported for WASP-17b and WASP-12b. To overcome biases associated with 1D atmospheric models, there is an urgent need to develop multidimensional retrieval techniques.