gebhart/patrepeval huggingface dataset:
A Multivariable Phase-Locked Loop-Integrated Controller for Enhanced Performance of Voltage Source Converters Under Weak Grid Conditions (2022)

This article proposes a new control strategy in stationary frame to improve the operational robustness of voltage source converters (VSCs) under weak grid conditions. First, dynamics of the phase-locked loop (PLL) are incorporated into the model of a grid-connected VSC in stationary reference frame. It is rigorously shown that the three-phase PLL introduces cross-coupling terms between the two control channels. Second, based on the augmented model, a multivariable controller is proposed which combines the current control feedback gains with PLL feedback gains. Third, the gains of the controller are designed using an optimal control theory approach. It is shown through theoretical analysis, computer simulations, and a laboratory experimental setup that the proposed controller improves the stability margins of the VSC during weak grid conditions. More specifically, under a given identical operating conditions, while the conventional controller’s responses become increasingly oscillatory for short-circuit ratio (SCR) below 1.95 and eventually becomes unstable at SCR=1.26, the proposed controller exhibits smooth and stable responses for SCR as low as 1. The proposed controller also produces cleaner sinusoidal currents during unbalanced grid voltages.
Voltage distortion in distribution feeders with nonlinear loads (1994)

The voltage of three real-life 13.8 kV feeders supplying customers with nonlinear loads was analyzed by means of computer simulations. Three classes of nonlinear loads were considered. Each class is characteristic for different types of AC to DC converters such as the input DC supply used for adjustable-speed-drives, battery chargers, PCs, TVs and electronically ballasted lights. The analysis is based on the determination of the most harmonic susceptible busses and their response to each harmonic frequency. A new expeditive method that takes into account the background harmonic voltage phasor, and an equivalent bus impedance was developed and used to compute the maximum nonlinear loads that yields VTHD=5%, (voltage total harmonic distortion). The main conclusion of this work is that when mitigation methods are not used, for a 15 kV class feeder with a maximum 10 MVA installed load, the total nonlinear residential load should not exceed 300 kW if the ITHD<90% (current total harmonic distortion), and 100 kW if ITHD>100%.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>
Synthetic applications of N-N linked heterocycles. Part 8. Regiospecific synthesis of 4-(α-acylalkyl)pyridines by attack of lithium enolates of ketones γ to N-(2,6-dimethyl-4-oxopyridin-1-yl)pyridinium salts (1980)

The addition of N-(2,6-dimethyl-4-oxopyridin-1-yl)pyridinium salts (2)–(4) to lithium enolates (1) of ketones in tetrahydrofuran at low temperatures gives regiospecifically high yields of 1,4-dihydro-adducts (5)–(7). These are readily isolated and can be decomposed under free-radical conditions, also in high yield, to 4-(α-acylalkyl)pyridines (8)–(10). Unsymmetrical dialkyl ketones give a mixture of two isomeric products, the ratio depending upon reaction conditions and steric factors. αβ-Unsaturated ketones, however, give products resulting from reaction exclusively at the position α′ to the carbonyl group.
Structural elucidation of amino amide‐type local anesthetic drugs and their main metabolites in urine by LC‐MS after derivatization and its application for differentiation between positional isomers of prilocaine (2020)

The demand for clinical toxicology analytical methods for identifying drugs of abuse and medicinal drugs is steadily increasing. Structural elucidation of amino amide-type local anesthetic drugs and their main metabolites by GC-EI-MS and LC-ESI-MS/MS is of great analytical challenge. These compounds exhibit only/mostly fragments/product ions representing the amine-containing residue, while the aromatic amide moiety remains unidentified. This task becomes even more complicated when discrimination between positional isomers of such compounds is required. Here, we report the development of a derivatization procedure for the differentiation and structural elucidation of a mixture of local anesthetic drugs and their metabolites that possess tertiary and secondary amines in water and urine. A method based on two sequential "in-vial" instantaneous derivatization processes at ambient temperature followed by LC-ESI-MS/MS analysis was developed. 2,2,2-Trichloro-1,1-dimethylethyl chloroformate (TCDMECF) was utilized to selectively convert the secondary amines into their carbamate derivatives, followed by hydrogen peroxide addition to produce the corresponding tertiary amine oxides. The resulting derivatives exhibited rich fragmentation patterns, enabling improved structural elucidation of the original compounds. The developed method was successfully applied to the differentiation and structural elucidation of prilocaine and its four positional isomers, which all possess similar GC and LC retention times and four of them exhibit almost identical EI-MS and ESI-MS/MS spectra, enabling their structural elucidation in a single LC-ESI-MS/MS analysis. The developed technique is fast and simple and enables discrimination between isomers based on different diagnostic ions/fragmentation patterns.
A New Type of Hydrogen Bond (1998)

Hydrogen bonding is responsible for a wide array of chemical properties, from the melting point of water to the behavior of enzymes. In his Perspective, Crabtree discusses recent work in which entirely new kinds of hydrogen bonds have been discovered. Understanding and controlling these new types of bonding may enable researchers to harness a variety of important catalytic processes.
Role of geometry and fluid properties in droplet and thread formation processes in planar flow focusing (2009)

Droplet formation processes in microfluidic flow focusing devices have been examined previously and some of the key physical mechanisms for droplet formation revealed. However, the underlying physical behavior is still too poorly understood to utilize it for generating droplets of precise size. In this work, we formulate scaling arguments to define dimensionless variables which capture all the parameters that control the droplet breakup process, including the flow rates and the viscosities of the two immiscible fluids, the interfacial tension between the fluids and the numerous dimensions in the flow focusing device. To test these arguments, we perform flow focusing experiments and systematically vary the dimensional parameters. Through these experiments, we confirm the validity of the scaling arguments and find a power law relationship between the normalized droplet size and the capillary number. We demonstrate that droplet formation can be separated into an upstream process for primary droplet formation and a downstream process for thread formation. These results are key to the ability to tune the flow focusing process for specific applications that require monodisperse micron and submicron droplets and particles.
Quantization as histogram segmentation: globally optimal scalar quantizer design in network systems (2003)

We propose a polynomial-time algorithm for optimal scalar quantizer design on discrete-alphabet sources. Special cases of the proposed approach yield optimal design algorithms for fixed-rate and entropy-constrained scalar quantizers, multi-resolution scalar quantizers, multiple description scalar quantizers, and Wyner-Ziv scalar quantizers. The algorithm guarantees globally optimal solutions for fixed-rate and entropy-constrained scalar quantizers and constrained optima for the other coding scenarios. We derive the algorithm by demonstrating the connection between scalar quantization, histogram segmentation, and the shortest path problem in a certain directed acyclic graph.
Socioeconomic Barriers to Informed Decisionmaking Regarding Maternal Serum Screening for Down Syndrome: Results of the French National Perinatal Survey of 1998 (2004)

Rather than representing informed decisionmaking, socioeconomic disparities in screening for Down syndrome are mostly due to limits in access or to information.
Hydrogel Swelling-Mediated Strain Induces Cell Alignment at Dentin Interfaces (2022)

Cell and tissue alignment is a defining feature of periodontal tissues. Therefore, the development of scaffolds that can guide alignment of periodontal ligament cells (PDLCs) relative to tooth root (dentin) surfaces is highly relevant for periodontal tissue engineering. To control PDLC alignment adjacent to the dentin surface, poly(ethylene glycol) (PEG)-based hydrogels were explored as a highly tunable matrix for encapsulating cells and directing their activity. Specifically, a composite system consisting of dentin blocks, PEG hydrogels, and PDLCs was created to control PDLC alignment through hydrogel swelling. PDLCs in composites with minimal hydrogel swelling showed random alignment adjacent to dentin blocks. In direct contrast, the presence of hydrogel swelling resulted in PDLC alignment perpendicular to the dentin surface, with the degree and extension of alignment increasing as a function of swelling. Replicating this phenomenon with different molds, block materials, and cells, together with predictive modeling, indicated that PDLC alignment was primarily a biomechanical response to swelling-mediated strain. Altogether, this study describes a novel method for inducing cell alignment adjacent to stiff surfaces through applied strain and provides a model for the study and engineering of periodontal and other aligned tissues.
Flow imaging microscopy as a novel tool for high-throughput evaluation of elastin-like polymer coacervates (2019)

Biological and bioinspired polymer microparticles have broad biomedical and industrial applications, including drug delivery, tissue engineering, surface modification, environmental remediation, imaging, and sensing. Full realization of the potential of biopolymer microparticles will require methods for rigorous characterization of particle sizes, morphologies, and dynamics, so that researchers may correlate particle characteristics with synthesis methods and desired functions. Toward this end, we evaluated biopolymer microparticles using flow imaging microscopy. This technology is widely used in the biopharmaceutical industry but is not yet well-known among the materials community. Our polymer, a genetically engineered elastin-like polypeptide (ELP), self-assembles into micron-scale coacervates. We performed flow imaging of ELP coacervates using two different instruments, one with a lower size limit of approximately 2 microns, the other with a lower size limit of approximately 300 nanometers. We validated flow imaging results by comparison with dynamic light scattering and atomic force microscopy analyses. We explored the effects of various solvent conditions on ELP coacervate size, morphology, and behavior, such as the dispersion of single particles versus aggregates. We found that flow imaging is a superior tool for rapid and thorough particle analysis of ELP coacervates in solution. We anticipate that researchers studying many types of microscale protein or polymer assemblies will be interested in flow imaging as a tool for quantitative, solution-based characterization.
Analysis of a photonic instantaneous frequency measurement system based on incoherent light sources and dispersion compensation techniques (2011)

A photonic approach for instantaneous frequency measurement (P-IFM) with tunable measurement range has been proposed and analyzed. In this paper, incoherent light sources are modulated with Mach-Zehnder Modulator and Phase Modulator simultaneously to obtain complementary frequency responses. A fixed relationship is established between microwave power and frequency through Amplitude Comparison Function (ACF) which increases monotonically over a large frequency band. As constituent parameters, wavelength difference of the incoherent sources and dispersion coefficient both are found to be strongly influential regarding measured frequency. Employment of tunable laser source and dispersion compensation techniques ensures real time response, stability and tunable measurement range.
Effect of Type of Alcoholic Beverages on Carbohydrate‐Deficient Transferrin, Sialic Acid, and Liver Enzymes (2003)

Background: There are only limited data obtained under well controlled conditions on the effects of moderate drinking on markers of alcohol use disorders. The aim of this study was to investigate the effects of moderate intake of different alcoholic beverages on these markers, including carbohydrate‐deficient transferrin (CDT), sialic acid (SA), and the liver enzymes γ‐glutamyltransferase, aspartate aminotransferase, and alanine aminotransferase. Methods: Eleven apparently healthy, nonsmoking middle‐aged men were included in a 12‐week randomized, diet‐controlled crossover trial according to a 4 × 4 Latin‐square design. Changes in CDT, SA, γ‐glutamyltransferase, aspartate aminotransferase, and alanine aminotransferase were analyzed after 3 weeks of daily intake of four glasses (40 g of alcohol) of red wine, beer, spirits (Dutch gin), or water (control). Results: After 3 weeks’ daily consumption of red wine, a significant decrease of serum CDT concentration was observed compared with water consumption. There was no effect of any alcoholic beverage on the other outcome measures. Conclusions: Daily consumption of 40 g of alcohol from different types of alcoholic beverages with dinner did not affect SA or liver enzymes. Further investigations to explore the mechanisms for the red wine–induced decreases of CDT, including changes in iron metabolism, are clearly needed.
Effects of Percutaneous Transluminal Angioplasty of Superficial Femoral Artery on Photoplethysmographic Pulse Transit Times (2018)

We analyze the changes in upper and lower limb pulse transit times (PTT) caused by peripheral artery disease (PAD) and its treatment with percutaneous transluminal angioplasty (PTA) of the superficial femoral artery. PTTs were extracted from the photoplethysmograms (PPG) recorded from an index finger and 2nd toes. PTTs were defined between the R-peaks of the ECG and different reference points of the PPG: foot and peak points, maxima of 1st and 2nd derivative, and by means of intersecting tangents method. Also the PTTs between the toe and finger pulses were analyzed. Our sample consists of 24 subjects examined before and after the PTA and in 1-month follow-up visit. Also 28 older than 65 years controls having normal ankle-to-brachial pressure index (ABI) and no history in cardiovascular diseases as well as 21 younger subjects were examined. The differences between the groups and pre- and post-treatment phases were analyzed by means of non-parametric statistical tests. The changes in the PTTs of upper limb and non-treated lower limb were negligible. The agreement with the reference values, ABI and toe pressures, was studied by kappa-analysis, resulting in kappa-values of 0.33-0.91. Differences in PTTs were found between pre-treatment state of the treated limb, post-treatment state and the follow-up visit, as well as between the pre-treatment state and controls. If patients' age and systolic blood pressure were taken into consideration, the method of lower limb PTT calculation from the peak point turns out feasible in finding the markers of PAD and monitoring post-treatment vascular remodellation.
A Method for Determining the Dynamic Response of an Elastic Load Cell Element (1970)

A method has been developed for determining the dynamic characteristics of a load cell element by subjecting it to sinusoidally time dependent forces, and an experiment using a piezoelectric shaker is described which illustrates the feasibility of the method. At present a simple viscoelastic model is assumed for the load cell element, and relaxation times on the order of 10−7 sec have been measured. The application of this information to load cells subjected to other types of dynamic forces is also discussed.
High resolution electron energy loss spectroscopy and photoelectron emission microscopy study of Fomblin Y on molybdenum surfaces (1997)

High resolution electron energy loss spectroscopy was used to measure the vibrational frequencies of in situ deposited films of Fomblin Y on polycrystalline molybdenum. Molecular Fomblin Y vibrations are identified as follows: 35 meV (chain wag); 68 meV, δ(CF3); 88 meV, δ(OCO); 125 meV, ν(CF3−C−CF2); 157 meV, νs(CF3); and 314 meV, 2νs(CF3). The thermal decomposition and electron stimulated decomposition of Fomblin Y on polycrystalline molybdenum have also been investigated. In both cases initial fragmentation of the lubricant molecule proceeds with the disappearance of the vibrational modes at 32 and 88 meV. The decomposition pathways then proceed differently for the respective degradation processes. Thin films of fluorinated lubricants have also been imaged with photoelectron emission microscopy on a rotating cylindrical polycrystalline molybdenum sample. In situ stylus contact is imaged in situ and in real-time. Areas of lubrication are clearly resolved in the image, as are wear tracks formed by contact with the lubricated and clean areas of the surface.
Hyperspectral Remote Sensing Image Classification Based on Partitioned Random Projection Algorithm (2022)

Dimensionality reduction based on random projection (RP) includes two problems, namely, the dimensionality is limited by the data size and the class separability of the dimensionality reduction results is unstable due to the randomly generated projection matrix. These problems make the RP algorithm unsuitable for large-size hyperspectral image (HSI) classification. To solve these problems, this paper presents a new partitioned RP (PRP) algorithm and proves its rationality in theory. First, a large-size HSI is evenly divided into multiple small-size sub-HSIs. Afterwards, the projection matrix that maximizes the class separability is selected from multiple samplings in which the class dissimilarity measurement is defined as large inter-class distance and small intra-class variance. By using the same projection matrix, each small-size sub-HSI is projected to generate a low dimensional sub-HSI, thereby generating a low dimensional HSI. Next, the minimum distance (MD) classifier is utilized to classify the low dimensional HSI obtained by the PRP algorithm. Finally, four real HSIs are used for experiments, and three of the most popular classification algorithms based on RP are selected as comparison algorithms to validate the effectiveness of the proposed algorithm. The classification performance is evaluated with the kappa coefficient, overall accuracy (OA), average accuracy (AA), average precision rate (APR), and running time. Experimental results indicate that the proposed algorithm can obtain reliable classification results in a very short time.
Performance of thin-film transistors with ultrathin Ni-MILC polycrystalline silicon channel layers (1999)

High-performance, low-temperature processed thin-film transistors (TFTs) with ultrathin (30-nm) metal induced laterally crystallized (MILC) channel layers were fabricated and characterized. Compared with the MILC TFTs with thicker (100 nm) channel layers, the ones with the 30-nm channel layers exhibit lower threshold voltage, steeper subthreshold slope, and higher transconductance. Furthermore, the comparatively lower off-state leakage current and the higher on-state current of the "thin" devices also imply a higher on/off ratio. At a drain voltage of 5 V, an on/off ratio of about 3/spl times/10/sup 7/ was obtained for the 30-nm TFTs, which is about 100 times better than that of the 100-nm TFT's. No deliberate hydrogenation was performed on these devices.
Fault-Tolerant Nonredundant Broadcasting in Hypercubes. (1992)

CABG alone yields good long-term outcome in selected angina-free patients with ischemic systolic dysfunction and advanced heart failure. However, associated diastolic impairment, reflected by elevated LVEDP, predicts reduced long-term survival despite myocardial viability.
Exposure to foodborne and orofecal microbes versus airborne viruses in relation to atopy and allergic asthma: epidemiological study (2000)

Respiratory allergy is less frequent in people heavily exposed to orofecal and foodborne microbes. Hygiene and a westernised, semisterile diet may facilitate atopy by influencing the overall pattern of commensals and pathogens that stimulate the gut associated lymphoid tissue thus contributing to the epidemic of allergic asthma and rhinitis in developed countries.
Progeroid facial features and lipodystrophy associated with a novel splice site mutation in the final intron of the FBN1 gene (2011)

The association of progeroid features and lipodystrophy was very recently described in a female adult with additional manifestations of Marfan syndrome. Mutation analysis of the fibrillin I (FBN1) gene revealed a novel heterozygous frameshift mutation at the 3' end in that patient. Here, we report on a 3.5-year-old girl with progeroid facial signs of neonatal onset, lipodystrophy, large head circumference with corresponding hydrocephaly, and tall stature at the end of infancy. Her facial appearance showed convincing clinical similarities to the above-mentioned case. We identified a novel heterozygous de novo splice site mutation c.8226+1G>T affecting the last intron of FBN1. We suggest a specific clinical entity characterized by progeroid facial features, lipodystrophy, and at least some clinical signs of Marfan syndrome is associated with a subset of mutations located at the 3' end of FBN1. This phenotype which is different from that of classical Marfan syndrome could be caused by a truncated FBN1 protein which could escape nonsense-mediated RNA decay.
Decline of speech understanding and auditory thresholds in the elderly (2005)

A group of 29 elderly subjects between 60.0 and 83.7 years of age at the beginning of the study, and whose hearing loss was not greater than moderate, was tested twice, an average of 5.27 years apart. The tests measured pure-tone thresholds, word recognition in quiet, and understanding of speech with various types of distortion (low-pass filtering, time compression) or interference (single speaker, babble noise, reverberation). Performance declined consistently and significantly between the two testing phases. In addition, the variability of speech understanding measures increased significantly between testing phases, though the variability of audiometric measurements did not. A right-ear superiority was observed but this lateral asymmetry did not increase between testing phases. Comparison of the elderly subjects with a group of young subjects with normal hearing shows that the decline of speech understanding measures accelerated significantly relative to the decline in audiometric measures in the seventh to ninth decades of life. On the assumption that speech understanding depends linearly on age and audiometric variables, there is evidence that this linear relationship changes with age, suggesting that not only the accuracy but also the nature of speech understanding evolves with age.