RESUMO
The Religious Order Study and Memory and Aging Project (ROSMAP) is an initiative that integrates two longitudinal cohort studies, which have been collecting clinicopathological and molecular data since the early 1990s. This extensive dataset includes a wide array of omic data, revealing the complex interactions between molecular levels in neurodegenerative diseases (ND) and aging. Neurodegenerative diseases (ND) are frequently associated with morbidity and cognitive decline in older adults. Omics research, in conjunction with clinical variables, is crucial for advancing our understanding of the diagnosis and treatment of neurodegenerative diseases. This summary reviews the extensive omics research-encompassing genomics, transcriptomics, proteomics, metabolomics, epigenomics, and multiomics-conducted through the ROSMAP study. It highlights the significant advancements in understanding the mechanisms underlying neurodegenerative diseases, with a particular focus on Alzheimer's disease.
RESUMO
Fractal lattices, with their self-similar and intricate structures, offer potential platforms for engineering physical properties on the nanoscale and also for realizing and manipulating high order topological insulator states in novel ways. Here we present a theoretical study on localized corner and edge states, emerging from topological phases in Sierpinski Carpet within a $\pi$-flux regime. A topological phase diagram is presented correlating the quadrupole moment with different hopping parameters. Particular localized states are identified following spatial signatures in distinct fractal generations. The specific geometry and scaling properties of the fractal systems can guide the supported topological states types and their associated functionalities. A conductive device is proposed by coupling identical Sierpinski Carpet units providing transport response through projected edge states which carry on the details of the system's topology. Our findings suggest that fractal lattices may also work as alternative routes to tune energy channels in different devices.
RESUMO
Background: Asthma onset or worsening of the disease in adulthood may be associated with occupational asthma (OA) or work-exacerbated asthma (WEA). Oscillometry and respiratory modeling offer insight into the pathophysiology and contribute to the early diagnosis of respiratory abnormalities. Purpose: This study aims to compare the changes due to OA and WEA and evaluate the diagnostic accuracy of this method. Patients and Methods: Ninety-nine volunteers were evaluated: 33 in the control group, 33 in the OA group, and 33 in the WEA group. The area under the receiver operator characteristic curve (AUC) was used to describe diagnostic accuracy. Results: Oscillometric analysis showed increased resistance at 4 hz (R4, p<0.001), 20 hz (R20, p<0.05), R4-R20 (p<0.0001), and respiratory work (p<0.001). Similar analysis showed reductions in dynamic compliance (p<0.001) and ventilation homogeneity, as evaluated by resonance frequency (Fr, p<0.0001) and reactance area (p<0.0001). Respiratory modeling showed increased peripheral resistance (p<0.0001), hysteresivity (p<0.0001), and damping (p<0.0001). No significant changes were observed comparing OA with WEA in any parameter. For OA, the diagnostic accuracy analyses showed Fr as the most accurate among oscillometric parameters (AUC=0.938), while the most accurate from respiratory modeling was hysteresivity (AUC=0.991). A similar analysis for WEA also showed that Fr was the most accurate among traditional parameters (AUC=0.972), and hysteresivity was the most accurate from modeling (AUC=0.987). The evaluation of differential diagnosis showed low accuracy. Conclusion: Oscillometry and modeling have advanced our understanding of respiratory abnormalities in OA and WEA. Furthermore, our study presents evidence suggesting that these models could aid in the early diagnosis of these diseases. Respiratory oscillometry examinations necessitate only tidal breathing and are straightforward to conduct. Collectively, these practical considerations, coupled with the findings of our study, indicate that respiratory oscillometry in conjunction with respiratory modeling, may enhance lung function assessments in OA and WEA.
RESUMO
We study the effects of the chemical short-range order (SRO) on the thermal conductivity of the refractory high-entropy alloy HfNbTaTiZr using atomistic simulation. Samples with different degrees of chemical SRO are prepared by a Monte Carlo scheme. With increasing SRO, a tendency of forming HfTi and TiZr clusters is found. The phonon density of states is determined from the velocity auto-correlation function and chemical SRO modifies the high-frequency part of the phonon density of states. Lattice heat conductivity is calculated by non-equilibrium molecular dynamics simulations. The heat conductivity of the random alloy is lower than that of the segregated binary alloys. Phonon scattering by SRO precipitates might be expected to reduce scattering times and, therefore, decrease thermal conductivity. We find that, in contrast, due to the increase of the conductivity alongside SRO cluster percolation pathways, SRO increases the lattice heat conductivity by around 12 %. This is expected to be a general result, extending to other HEAs.
RESUMO
Adverse childhood experiences (ACEs) are associated with externalizing behaviors. Whereas some ACEs affect individual children (i.e., child-specific; e.g., failing a grade), others affect the family unit (i.e., family-wide; e.g., parent losing a job); effects of ACEs on externalizing behavior may manifest differently across groupings of ACEs. Moreover, birth order may modify the association between child-specific and family-wide ACEs and externalizing behavior due to differences in the experience of being a younger versus older sibling. This study examined the externalizing behavior of siblings in relation to their experiences of child-specific and family-wide ACEs to test the hypothesis that younger siblings are at greater risk for developing externalizing symptoms following familial ACE exposure. Participants were 61 sibling pairs (younger sibling Mage = 11.37 years, 44.1% male; older sibling Mage = 13.1 years, 52.5% male) recruited from six schools in the northeastern United States. Parents rated each child's externalizing behaviors (e.g., bullying, meanness) and retrospectively reported on each child's experience of 34 ACEs; two raters categorized ACEs as child-specific (n = 10) or family-wide (n = 24). Multilevel modeling revealed that both child-specific and family-wide ACEs were associated with increased externalizing behaviors. Birth order moderated the effect of family-wide (but not child-specific) ACEs on externalizing behaviors, independent of sex and age. Externalizing behavior was higher for younger siblings as compared with older siblings, particularly when a high number of ACEs (6+) were reported. This research should prompt future exploration of mechanistic theories of the impact of family-wide and child-specific ACEs and the role of birth order.
RESUMO
In the present study, both short-range and long-range structural features of an ionic bridged silsesquioxane, specifically one containing the 1,4-diazoniabicyclo[2.2.2]octane chloride group (ISSQ), were elucidated. This ionic silsesquioxane was synthesized via direct polycondensation of a bridged organosilane precursor, without any additional functionalization step. Si-O-Si cage structures typical of Polyhedral Oligomeric Silsesquioxanes (POSS) were identified. The average interatomic distances of the POSS cages, including the open T8 cage and the T12 cage for the ISSQ, as well as the T8 cage for a commercially available pendant POSS were determined. It is the first report of the interatomic distance determination of POSS cage; achieved by using total pair distribution function G(r) values obtained through high-resolution synchrotron X-ray diffraction combined with density functional theory (DFT) calculations. The application of DFT was crucial for accurately assigning X-ray peaks and verifying structural details. Furthermore, the analysis of X-ray diffraction peaks and the examination of crystalline domains via transmission electron microscopy enabled the proposal of a hexagonal arrangement of Si-O-Si cages over long ranges within the ionic bridged silsesquioxane. This proposed arrangement highlights a distinctive structural organization that could impact the material's properties and applications.
RESUMO
Intramolecular charge transfer (ICT) effects of para-nitroaniline (pNA) in eight solvents (cyclohexane, toluene, acetic acid, dichloroethane, acetone, acetonitrile, dimethylsulfoxide, and water) are investigated extensively. The second-order algebraic diagrammatic construction, ADC(2), ab initio wave function is employed with the COSMO implicit and discrete multiscale solvation methods. We found a decreasing amine group torsion angle with increased solvent polarity and a linear correlation between the polarity and ADC(2) transition energies. The first absorption band involves π â π* transitions with ICT from the amine and the benzene ring to the nitro group, increased by 4%-11% for different solvation models of water compared to the vacuum. A second band of pNA is characterized for the first time. This band is primarily a local excitation on the nitro group, including some ICT from the amine group to the benzene ring that decreases with the solvent polarity. For cyclohexane, the COSMO implicit solvent model shows the best agreement with the experiment, while the explicit model has the best agreement for water.
RESUMO
The first step in comprehending the properties of Au10 clusters is understanding the lowest energy structure at low and high temperatures. Functional materials operate at finite temperatures; however, energy computations employing density functional theory (DFT) methodology are typically carried out at zero temperature, leaving many properties unexplored. This study explored the potential and free energy surface of the neutral Au10 nanocluster at a finite temperature, employing a genetic algorithm coupled with DFT and nanothermodynamics. Furthermore, we computed the thermal population and infrared Boltzmann spectrum at a finite temperature and compared it with the validated experimental data. Moreover, we performed the chemical bonding analysis using the quantum theory of atoms in molecules (QTAIM) approach and the adaptive natural density partitioning method (AdNDP) to shed light on the bonding of Au atoms in the low-energy structures. In the calculations, we take into consideration the relativistic effects through the zero-order regular approximation (ZORA), the dispersion through Grimme's dispersion with Becke-Johnson damping (D3BJ), and we employed nanothermodynamics to consider temperature contributions. Small Au clusters prefer the planar shape, and the transition from 2D to 3D could take place at atomic clusters consisting of ten atoms, which could be affected by temperature, relativistic effects, and dispersion. We analyzed the energetic ordering of structures calculated using DFT with ZORA and single-point energy calculation employing the DLPNO-CCSD(T) methodology. Our findings indicate that the planar lowest energy structure computed with DFT is not the lowest energy structure computed at the DLPN0-CCSD(T) level of theory. The computed thermal population indicates that the 2D elongated hexagon configuration strongly dominates at a temperature range of 50-800 K. Based on the thermal population, at a temperature of 100 K, the computed IR Boltzmann spectrum agrees with the experimental IR spectrum. The chemical bonding analysis on the lowest energy structure indicates that the cluster bond is due only to the electrons of the 6 s orbital, and the Au d orbitals do not participate in the bonding of this system.
RESUMO
The purpose of this paper is to delve into the ethical aspects experienced by the healthcare team when they receive the directive to limit therapeutic effort or a do-not-resuscitate order. From an interpretative, qualitative paradigm with a content analysis approach, a process based on three phases was conducted: pre-analysis in which categories were identified, the projection of the analysis, and inductive analysis. During 2023, interviews were conducted in the clinical setting of a high-complexity hospital in Chile with 56 members of the healthcare teams from critical and emergency units, from which four categories emerged: a) the risk of violating patients' rights by using do-not-resuscitate orders and limiting therapeutic effort; b) the gap in the interpretation of the legal framework addressing the care and attention of patients at the end of life or with terminal illnesses by the healthcare team; c) ethical conflicts in end-of-life care; and d) efficient care versus holistic care in patients with terminal illness. There are significant gaps in bioethics training and aspects of a good death in healthcare teams facing the directive to limit therapeutic effort and not resuscitate. It is suggested to train personnel and work on a consensus guide to address the ethical aspects of a good death.
El propósito de este trabajo es profundizar en los aspectos éticos que experimenta el equipo de salud cuando reciben la indicación de limitar el esfuerzo terapéutico o la orden de no reanimar. Desde un paradigma interpretativo, cualitativo y con un enfoque de análisis de contenido, se realizó un proceso basado en tres fases: preanálisis en el que se identificaron las categorías, la proyección del análisis y el análisis inductivo. Durante 2023, se realizaron entrevistas en el entorno clínico de un hospital de alta complejidad en Chile a 56 miembros de equipos de salud de unidades críticas y urgencias, de las que emergieron cuatro categorías: a) riesgo de vulnerar los derechos de los pacientes al utilizar la orden de no reanimar, y limitación del esfuerzo terapéutico; b) brecha en la interpretación del marco legal que aborda la atención y cuidado de pacientes al final de la vida, o con enfermedades terminales por parte del equipo de salud; c) conflictos éticos de la atención al final de la vida; y d) el cuidado eficiente o el cuidado holístico en pacientes con enfermedad terminal. Existen brechas importantes en la formación en bioética y aspectos del buen morir en los equipos de salud que se enfrentan a la orden de limitar el esfuerzo terapéutico y no reanimar. Se sugiere capacitar al personal, y trabajar una guía de consenso para abordar los aspectos éticos del buen morir.
Assuntos
Equipe de Assistência ao Paciente , Pesquisa Qualitativa , Ordens quanto à Conduta (Ética Médica) , Assistência Terminal , Humanos , Chile , Ordens quanto à Conduta (Ética Médica)/ética , Ordens quanto à Conduta (Ética Médica)/legislação & jurisprudência , Equipe de Assistência ao Paciente/ética , Assistência Terminal/ética , Direitos do Paciente/ética , Feminino , Masculino , Atitude do Pessoal de Saúde , Entrevistas como AssuntoRESUMO
BACKGROUND: Physics-informed neural networks (PINNs) have emerged as a powerful tool for solving inverse problems, especially in cases where no complete information about the system is known and scatter measurements are available. This is especially useful in hemodynamics since the boundary information is often difficult to model, and high-quality blood flow measurements are generally hard to obtain. METHODS: In this work, we use the PINNs methodology for estimating reduced-order model parameters and the full velocity field from scatter 2D noisy measurements in the aorta. Two different flow regimes, stationary and transient were studied. RESULTS: We show robust and relatively accurate parameter estimations when using the method with simulated data, while the velocity reconstruction accuracy shows dependence on the measurement quality and the flow pattern complexity. Comparison with a Kalman filter approach shows similar results when the number of parameters to be estimated is low to medium. For a higher number of parameters, only PINNs were capable of achieving good results. CONCLUSION: The method opens a door to deep-learning-driven methods in the simulations of complex coupled physical systems.
Assuntos
Modelos Cardiovasculares , Redes Neurais de Computação , Humanos , Velocidade do Fluxo Sanguíneo/fisiologia , Hemodinâmica/fisiologia , Aorta/fisiologia , Simulação por ComputadorRESUMO
Primary studies have demonstrated that despite being useful, most of the drug-drug interaction (DDI) alerts generated by clinical decision support systems are overridden by prescribers. To provide more information about this issue, we conducted a systematic review and meta-analysis on the prevalence of DDI alerts generated by CDSS and alert overrides by physicians. The search strategy was implemented by applying the terms and MeSH headings and conducted in the MEDLINE/PubMed, EMBASE, Web of Science, Scopus, LILACS, and Google Scholar databases. Blinded reviewers screened 1873 records and 86 full studies, and 16 articles were included for analysis. The overall prevalence of alert generated by CDSS was 13% (CI95% 5-24%, p-value <0.0001, I^2 = 100%), and the overall prevalence of alert override by physicians was 90% (CI95% 85-95%, p-value <0.0001, I^2 = 100%). This systematic review and meta-analysis presents a high rate of alert overrides, even after CDSS adjustments that significantly reduced the number of alerts. After analyzing the articles included in this review, it was clear that the CDSS alerts physicians about potential DDI should be developed with a focus on the user experience, thus increasing their confidence and satisfaction, which may increase patient clinical safety.
Assuntos
Sistemas de Apoio a Decisões Clínicas , Interações Medicamentosas , Sistemas de Registro de Ordens Médicas , Sistemas de Apoio a Decisões Clínicas/estatística & dados numéricos , Humanos , Sistemas de Registro de Ordens Médicas/estatística & dados numéricos , Erros de Medicação/prevenção & controleRESUMO
The inconsistency in terminology for Cortical Visual Impairment or Cerebral Visual Impairment presents challenges: (1) different levels of changes in visual pathway and other cerebral areas do not allow discrimination; (2) different visual and oculomotor aspects are not adequately considered. We open a debate to consider a more appropriate diagnosis.
Assuntos
Terminologia como Assunto , Transtornos da Visão , Humanos , Transtornos da Visão/fisiopatologia , Transtornos da Visão/diagnóstico , Córtex Visual/fisiologia , Vias Visuais/fisiopatologiaRESUMO
The combination of signals from the T-cell receptor (TCR) and co-stimulatory molecules triggers transcriptional programs that lead to proliferation, cytokine secretion, and effector functions. We compared the impact of engaging the TCR with CD28 and/or CD43 at different time points relative to TCR engagement on T-cell function. TCR and CD43 simultaneous engagement resulted in higher CD69 and PD-1 expression levels than in TCR and CD28-stimulated cells, with a cytokine signature of mostly effector, inflammatory, and regulatory cytokines, while TCR and CD28-activated cells secreted all categories of cytokines, including stimulatory cytokines. Furthermore, the timing of CD43 engagement relative to TCR ligation, and to a lesser degree that of CD28, resulted in distinct patterns of expression of cytokines, chemokines, and growth factors. Complete cell activation was observed when CD28 or CD43 were engaged simultaneously with or before the TCR, but ligating the TCR before CD43 or CD28 failed to complete a cell activation program regarding cytokine secretion. As the order in which CD43 or CD28 and the TCR were engaged resulted in different combinations of cytokines that shape distinct T-cell immune programs, we analyzed their upstream sequences to assess whether the combinations of cytokines were associated with different sets of regulatory elements. We found that the order in which the TCR and CD28 or CD43 are engaged predicts the recruitment of specific sets of chromatin remodelers and TFSS, which ultimately regulate T-cell polarization and plasticity. Our data underscore that the combination of co-stimulatory molecules and the time when they are engaged relative to the TCR can change the cell differentiation program.
Assuntos
Antígenos CD28 , Receptores de Antígenos de Linfócitos T , Antígenos CD28/metabolismo , Receptores de Antígenos de Linfócitos T/metabolismo , Linfócitos T , Ativação Linfocitária , Diferenciação Celular , Citocinas/metabolismoRESUMO
Here, we presented a second-order scattering sensor based on the Zn0.97La0.03O compound (LaZnO) for selective and stable detection of glycated albumin (GA, glycemic long-term biomarker). The LaZnO sample was obtained through the co-precipitation method and then characterized using microscopic and spectroscopic techniques. Furthermore, the selectivity, molecular interference, temporal stability, and pH effects of the LaZnO SOS signal in the absence and presence of GA were investigated. The results indicate the stability of the SOS signal over more than 60 days. Assays conducted within the pH range of 5 to 8 indicate that the detection of GA remains unaffected under the given conditions. Selectivity studies show that the SOS signal of LaZnO is reduced only upon contact with GA, while interference studies show that detection is not affected by other chemical species. Additionally, the calibration curve test showed high sensitivity of the material, with a detection limit of 0.55 µg/ml. All the results suggest that LaZnO can deliver efficiency, selectivity, accuracy, and fast response as a GA biosensor, emphasizing LaZnO's usefulness in detecting protein biomarkers.
Assuntos
Albumina Sérica Glicada , Produtos Finais de Glicação Avançada , Albumina Sérica/metabolismo , Biomarcadores , Zinco , GlicemiaRESUMO
Background: Identification of unvaccinated children is important for preventing deaths due to infections. Number of siblings and birth order have been postulated as risk factors for zero-dose prevalence. Methods: We analysed nationally representative cross-sectional surveys from 85 low and middle-income countries (2010-2020) with information on immunisation status of children aged 12-35 months. Zero-dose prevalence was defined as the failure to receive any doses of DPT (diphtheria-pertussis-tetanus) vaccine. We examined associations with birth order and the number of siblings, adjusting for child's sex, maternal age and education, household wealth quintiles and place of residence. Poisson regression was used to calculate zero-dose prevalence ratios. Findings: We studied 375,548 children, of whom 13.7% (n = 51,450) were classified as zero-dose. Prevalence increased monotonically with birth order and with the number of siblings, with prevalence increasing from 11.0% for firstborn children to 17.1% for birth order 5 or higher, and from 10.5% for children with no siblings to 17.2% for those with four or more siblings. Adjustment for confounders attenuated but did not eliminate these associations. The number of siblings remained as a strong risk factor when adjusted for confounders and birth order, but the reverse was not observed. Among children with the same number of siblings, there was no clear pattern in zero-dose prevalence by birth order; for instance, among children with two siblings, the prevalence was 13.0%, 14.7%, and 13.3% for firstborn, second, and third-born, respectively. Similar results were observed for girls and boys. 9513 families had two children aged 12-35 months. When the younger sibling was unvaccinated, 61.9% of the older siblings were also unvaccinated. On the other hand, when the younger sibling was vaccinated, only 5.9% of the older siblings were unvaccinated. Interpretation: The number of siblings is a better predictor than birth order in identifying children to be targeted by immunization campaigns. Zero-dose children tend to be clustered within families. Funding: Gavi, the Vaccine Alliance.
RESUMO
PURPOSE: To analyze higher-order aberrations (HOAs) and their visual impact in a pediatric blepharokeratoconjunctivitis (PBKC) cohort compared with healthy controls. METHODS: Prospective case-control study of pediatric patients (≤ 16 years old). Subjects underwent wavefront aberrometry analysis to compare HOAs and their impact on visual quality. RESULTS: A total of 150 eyes from 76 patients were included in the analysis. The PBKC group consisted of 50 eyes and the control group of 100 healthy eyes. Mean age was 10.39 ± 3.81 years for the PBKC group and 10.80 ± 3.61 years for the controls. Mean corrected-distance visual acuity (CDVA) was 0.24 ± 0.21 logMAR in the PBKC group and 0.07 ± 0.1 in the controls (P < 0.001). Mean astigmatism was 1.6 ± 1.98D in the PBKC group vs. 0.67 ± 0.76D in the control group (P = 0.01). Mean RMS of HOAs was 1.05 ± 1.7mm in the PBKC group and 0.41 ± 0.18mm in the controls (P < 0.001). The mean modulation transfer function (MTF) in the PBKC group was significantly lower (16.37 ± 16.32) than controls (30.3 ± 23.57) (P < 0.001). Corneal leukomas, stromal vascularization, peripheral nummular subepithelial scars, and pannus formation are associated with increased HOAs. CONCLUSIONS: There was a significant increase in total HOAs of eyes with PBKC compared to healthy controls. Corneal opacity, vascularization, and scarring are associated with increased HOAs. The PBKC eye aberration profile: coma, secondary astigmatism, quadrafoil, and pentafoil, were associated with decreased CDVA and visual quality (PSF and MTF).
Assuntos
Astigmatismo , Opacidade da Córnea , Aberrações de Frente de Onda da Córnea , Humanos , Criança , Adolescente , Estudos de Casos e Controles , Acuidade Visual , Córnea , Refração OcularRESUMO
High Energy Ball-Milling (HEBM) modifies starchs' granule morphology, physicochemical properties, and chemical structure. However, understanding how the HEBM changes the starch chemical structure is necessary to control these modifications. Therefore, this study aimed to investigate the changes in potato starch's long- and short-range molecular order during HEBM at different environmental conditions such as oxygen (Air) and humidity content. Due to the correlation between the starch modification and the energy supplied (Esupp) by the HEBM, Burgio's equation was used to calculate this energy. The starch transformation was followed by X-ray diffraction, Fourier Transform-Infrared Spectroscopy, and Raman spectroscopy. A Principal Component Analysis (PCA) was conducted to reduce the HEBM variables. PAC analysis demonstrated that the different oxygen-humidity conditions do not affect the HEBM of potato starch. Based on the starch chemical structure transformation correlated with Esupp during HEBM, four stages were observed: orientation, modification, mechanolysis, and over-destruction. It was identified for the first time that at low milling energy (<1.5 kJ/g, orientation stage), the glycosidic rings change their orientation, and starch-water interaction increases while the starch's organization reduces. Ergo, the potato starch could be more susceptible to chemical modifications during the first two stages.
Assuntos
Solanum tuberosum , Solanum tuberosum/química , Amilose/química , Umidade , Oxigênio , Amido/química , Difração de Raios XRESUMO
In this study, we report the simultaneous determination of bromine and fluorine using Second-Order Calibration High-Resolution Continuum Source Graphite Furnace Molecular Absorption Spectrometry (HR CS MAS). The instrumental data acquired correspond to the time versus wavelength matrix per sample that were analyzed using Parallel Factor Analysis (PARAFAC), along with Unfold and N-way Partial Least Squares combined with a post-calibration step known as Residual Bilinearization (U and N PLS/RBL). Despite the significant difference in sensitivity between bromine and fluorine, all approaches provided reasonably accurate results when predicting both analytes in synthetic mixtures within a controlled environment. The relative prediction error (REP) values for bromine were 29.8 % (PARAFAC), 23.6 % (N-PLS/RBL), and 13.1 % (U-PLS/RBL), while for fluorine, the REP values were 3.4 % (PARAFAC), 3.5 % (N-PLS/RBL), and 3.2 % (U-PLS/RBL). When applying this approach to predict unknown samples, a comparison was made between the estimated nominal concentrations of fluorine and bromine obtained using either a reference method or based on labeled values or spiked mass, and those obtained using the proposed method. It was observed that PARAFAC was unable to predict the samples accurately, whereas the REP values for the prediction of bromine and fluorine using N-PLS/RBL and U-PLS/RBL methods were 19.3 %/19.2 % and 13.6 %/13.1 %, respectively.
RESUMO
Temporal (race) computing schemes rely on temporal memories, where information is represented with the timing of signal edges. Standard digital circuit techniques can be used to capture the relative timing characteristics of signal edges. However, the properties of emerging device technologies could be particularly exploited for more efficient circuit implementations. Specifically, the collective dynamics of networks of memristive devices could be leveraged to facilitate time-domain computations in emerging memristive memories. To this end, this work studies the star interconnect configuration of bipolar memristive devices. Through circuit simulations using a behavioral model of voltage-controlled bipolar memristive devices, we demonstrated the suitability of such circuits in two different contexts, namely sensing and "rank-order" coding. We particularly analyzed the conditions that the employed memristive devices should meet to guarantee the expected operation of the circuit and the possible effects of device variability in the storage and the reproduction of the information in arriving signal edges. The simulation results in LTSpice validate the correct operation and confirm the promising application prospects of such simple circuit structures, which, we show, natively exist in the crossbar geometry. Therefore, the star interconnect configuration could be considered for temporal computations inside resistive memory (ReRAM) arrays.
RESUMO
BACKGROUND: the chemometric processing of second-order chromatographic-spectral data is usually carried out with the aid of multivariate curve resolution-alternating least-squares (MCR-ALS). Recently, an alternative procedure was described based on the estimation of image moments for each data matrix and subsequent application of multiple linear regression after suitable variable selection. RESULTS: The analysis of both simulated and experimental data leads to the conclusion that the image moment method, although can cope with chromatographic lack of reproducibility across injections, it only performs well in the absence of uncalibrated interferents. MCR-ALS, on the other hand, provides good analytical results in all studied situations, whether the test samples contain uncalibrated interferents or not. SIGNIFICANCE: The results are useful to assess the real usefulness of newly proposed methodologies for second-order calibration in the case of chromatographic-spectral data sets, especially when samples contain unexpected chemical constituents.