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Spectral Analysis

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https://www.readbyqxmd.com/read/29786089/spectral-analysis-of-fundus-autofluorescence-pattern-as-a-tool-to-detect-early-stages-of-degeneration-in-the-retina-and-retinal-pigment-epithelium
#1
Tatiana B Feldman, Marina A Yakovleva, Andrey V Larichev, Patimat M Arbukhanova, Alexandra Sh Radchenko, Sergey A Borzenok, Vladimir A Kuzmin, Mikhail A Ostrovsky
PURPOSE: The aim of this work is the determination of quantitative diagnostic criteria based on the spectral characteristics of fundus autofluorescence to detect early stages of degeneration in the retina and retinal pigment epithelium (RPE). METHODS: RPE cell suspension samples were obtained from the cadaver eyes with and without signs of age-related macular degeneration (AMD). Fluorescence analysis at an excitation wavelength of 488 nm was performed. The fluorescence lifetimes of lipofuscin-granule fluorophores were measured by counting time-correlated photon method...
May 22, 2018: Eye
https://www.readbyqxmd.com/read/29785936/an-objective-parameter-to-classify-voice-signals-based-on-variation-in-energy-distribution
#2
Boquan Liu, Evan Polce, Jack Jiang
OBJECTIVES: The purpose of this paper is to introduce an iterative nonlinear weighted method based on the variation in spectral energy distribution present in a voice signal to differentiate between four voice types: type 1 voice signals are nearly periodic, type 2 voice signals have strong modulations and subharmonics, type 3 signals are chaotic, and type 4 signals are dominated by stochastic noise. STUDY DESIGN: A total of 135 voice signal samples of the sustained vowel /a/ were obtained from the Disordered Voice Database and then individually categorized into the appropriate voice types based on the classification system described in Sprecher et al (2010)...
May 18, 2018: Journal of Voice: Official Journal of the Voice Foundation
https://www.readbyqxmd.com/read/29785908/rapid-detection-of-adulteration-of-milks-from-different-species-using-fourier-transform-infrared-spectroscopy-ftir
#3
Olgun Cirak, N Cihat Icyer, M Zeki Durak
The aim of the studies reported in the Research Communication was to develop a rapid spectroscopic technique as an alternative method for the classification and discrimination of milk sources by Fourier transform infrared spectroscopy (FTIR). Cow, sheep and water buffalo milk samples were collected from various local milk producers in Istanbul, Turkey. In addition, various brands of packaged milk were purchased locally. Spectrums were obtained according to milk species origin and binary mixtures prepared in increments of 10% (10, 20, 30, 40, 50, 60, 70, 80 and 90%) for each sample analysed in FTIR spectroscopy...
May 2018: Journal of Dairy Research
https://www.readbyqxmd.com/read/29784418/transmission-infrared-imaging-microscopy-and-multivariate-curve-resolution-applied-to-the-forensic-examination-of-automotive-paints
#4
Francis Kwofie, Undugodage Don Nuwan Perera, Matthew D Allen, Barry K Lavine
In the forensic examination of automotive paint, each layer of paint is analyzed individually by infrared (IR) spectroscopy. Laboratories in North America typically hand section each layer and present each separated layer to the spectrometer for analysis, which is time consuming. In addition, sampling too close to the boundary between adjacent layers can pose a problem as it produces an IR spectrum that is a mixture of the two layers. Not having a "pure" spectrum of each layer will prevent a meaningful comparison between each paint layer or in the situation of searching an automotive database will prevent the forensic paint examiner from developing an accurate hit list of potential suspects...
August 15, 2018: Talanta
https://www.readbyqxmd.com/read/29784376/spectral-reconstruction-for-shifted-excitation-raman-difference-spectroscopy-serds
#5
Shuxia Guo, Olga Chernavskaia, Jürgen Popp, Thomas Bocklitz
Fluorescence emission is one of the major obstacles to apply Raman spectroscopy in biological investigations. It is usually several orders more intense than Raman scattering and hampers further analysis. In cases where the fluorescence emission is too intense to be efficiently removed via routine mathematical baseline correction algorithms, an alternative approach is needed. One alternative approach is shifted-excitation Raman difference spectroscopy (SERDS), where two Raman spectra are recorded with two slightly different excitation wavelengths...
August 15, 2018: Talanta
https://www.readbyqxmd.com/read/29784366/raman-spectroscopy-for-wine-analyses-a-comparison-with-near-and-mid-infrared-spectroscopy
#6
Cláudia A Teixeira Dos Santos, Ricardo N M J Páscoa, Patrícia A L S Porto, António L Cerdeira, J M González-Sáiz, C Pizarro, João A Lopes
Routine wine analysis are commonly employed to ensure the quality and safety standards, and to meet consumers' demands and legal requirements. In the last decades, efforts have been done in order to replace the traditional analytical techniques by vibrational spectroscopic techniques such as near infrared (NIR) and mid infrared (MIR) spectroscopy. The potential of these techniques has already been proved by several studies that revealed their ability for the determination of several wine parameters with high levels of precision and accuracy...
August 15, 2018: Talanta
https://www.readbyqxmd.com/read/29783139/inspection-of-baked-carbon-anodes-using-a-combination-of-multi-spectral-acousto-ultrasonic-techniques-and-principal-component-analysis
#7
Moez Ben Boubaker, Donald Picard, Carl Duchesne, Jayson Tessier, Houshang Alamdari, Mario Fafard
This paper reports on the application of an acousto-ultrasonic (AU) scheme for the inspection of industrial-size carbon anode blocks used in the production of primary aluminium by the Hall-Héroult process. A frequency-modulated wave is used to excite the anode blocks at multiple points. The collected attenuated AU signals are decomposed using the Discrete Wavelet Transform (DTW) after which vectors of features are calculated. Principal Component Analysis (PCA) is utilized to cluster the AU responses of the anodes...
May 17, 2018: Ultrasonics
https://www.readbyqxmd.com/read/29782806/analysis-of-sulfates-on-low-molecular-weight-heparin-using-mass-spectrometry-structural-characterization-of-enoxaparin
#8
Rohitesh Gupta, Moorthy P Ponnusamy
Structural characterization of Low Molecular Weight Heparin (LMWH) is critical to meet biosimilarity standards. In this context, the review focuses on structural analysis of labile sulfates attached to the side-groups of LMWH using mass spectrometry. A comprehensive review of this topic will help readers to identify key strategies for tackling the problem related to sulfate loss. At the same time, various mass spectrometry techniques are presented to facilitate compositional analysis of LMWH, mainly Enoxaparin...
May 21, 2018: Expert Review of Proteomics
https://www.readbyqxmd.com/read/29782796/resolution-measurement-from-a-single-reconstructed-cryo-em-density-map-with-multi-scale-spectral-analysis
#9
Yu-Jiao Yang, Shuai Wang, Biao Zhang, Hong-Bin Shen
As a relatively new technology to solve the 3D structure of a protein or protein complex, the Single-Particle Reconstruction (SPR) of cryo-EM images shows much superiority and is in a rapidly developing stage. Resolution measurement in SPR, which evaluates the quality of a reconstructed 3D density map, plays a critical role for promoting methodology development of SPR and structural biology. Due to there is no benchmark map in a new structure generation, how to realize the resolution estimation of a new map is still an open problem...
May 21, 2018: Journal of Chemical Information and Modeling
https://www.readbyqxmd.com/read/29781840/cardiovascular-autonomic-profile-in-women-with-constitutional-hypotension
#10
Giris Jacob, Franca Barbic, Meytal Glago, Franca Dipaola, Alberto Porta, Raffaello Furlan
BACKGROUND: Constitutional hypotension (CHT) is defined as a SBP below 105 mmHg. As autonomic-related symptoms are frequently reported in CHT, these symptoms suggest that the cardiovascular autonomic control is perturbed in individuals with CHT. METHODS: We investigated the autonomic cardiovascular control of 15 women with CHT and 12 women with NBP (SBP >110 mmHg). We monitored BP and ECG for autonomic function test. Supine and head up tilt (HUT) spectral analysis of RR interval and BP variability, baroreflex sensitivity and plasma levels of plasma renin activity and aldosterone were determined...
May 16, 2018: Journal of Hypertension
https://www.readbyqxmd.com/read/29781516/cardiac-autonomic-modulation-and-long-term-use-of-amiodarone-in-patients-with-chronic-chagasic-cardiopathy
#11
Henriette Elana Fortes Silva, Renan Sandoval de Almeida, Danilo Batista Silveira, Maurício Llaguno, Luiz Antônio Pertili Rodrigues Resende, Valdo José Dias da Silva, Dalmo Correia
BACKGROUND: Patients with chronic Chagas cardiopathy (CCC), which may be associated with cardiac arrhythmias, frequently use amiodarone, an anti-arrhythmic drug that, experimentally, appears to modulate the cardiac autonomic function. OBJECTIVE: The present cross-sectional observational study aimed to evaluate autonomic cardiac modulation in patients with CCC undergoing chronic amiodarone therapy. METHODS: Three groups were investigated: Group 1 included patients with CCC not treated with amiodarone (n = 27); Group 2 included patients with CCC with prolonged use (at least 6 months) of amiodarone (n = 16); and Group 3 including non-chagasic control patients (n = 23)...
May 21, 2018: Pacing and Clinical Electrophysiology: PACE
https://www.readbyqxmd.com/read/29781187/eeg-oscillations-during-caress-like-affective-haptic-elicitation
#12
Gaetano Valenza, Alberto Greco, Matteo Bianchi, Mimma Nardelli, Simone Rossi, Enzo Pasquale Scilingo
Noninvasive, objective quantitative techniques to gauge emotional states are fundamental for clinical psychology as they overcome subjective bias of currently used questionnaires. To this end, we investigated brain oscillatory EEG activity during caresslike, affective haptic elicitation conveyed on the forearm at two force (strength of the caress) and three velocity (velocity of the caress) levels. Thirty-two healthy subjects (16 female) were asked to assess each haptic stimulus in terms of arousal (i.e., intensity of emotional perception) and valence (i...
May 20, 2018: Psychophysiology
https://www.readbyqxmd.com/read/29781091/fetal-assessment-in-buprenorphine-maintained-women-using-fetal-magnetoencephalography-a-pilot-study
#13
Diana Escalona-Vargas, Jessica L Coker, Shona Ray-Griffith, Eric R Siegel, Curtis L Lowery, Zachary N Stowe, Hari Eswaran
BACKGROUND AND AIMS: In-utero exposure to opioids including buprenorphine (BUP) has been shown to affect fetal activity, specifically heart-rate variability (FHRV) and fetal movement (FM). Our objective was to extract simultaneous recordings of fetal cardiac, and brain-related activity in BUP-maintained and non-opioid exposed pregnant women using a novel non-invasive biomagnetic technique. DESIGN: A pilot study was conducted, recording and analyzing biomagnetic data from fetuses of BUP-maintained and non-opioid exposed pregnant women...
May 20, 2018: Addiction
https://www.readbyqxmd.com/read/29780311/characteristics-of-rest-and-postural-tremors-in-parkinson-s-disease-an-analysis-of-motor-unit-firing-synchrony-and-patterns
#14
Orsalia M Agapaki, Constantinos N Christakos, Dimitrios Anastasopoulos
The neural mechanisms responsible for resting and postural tremor in Parkinson's disease (PD) have been the object of considerable study, much of it focusing on supraspinal sites. Here, we adopted an alternative approach that emphasizes motor unit (MU) firing synchrony and patterns of discharge. To explore if these could account for known features of PD tremor, we recorded the instantaneous acceleration of the upper limb of 23 PD patients at rest or while they tried to hold a stable posture together with surface EMG and single MU discharges of upper limb muscles...
2018: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/29779188/vitreomacular-interface-abnormalities-in-patients-with-diabetic-macular-oedema-and-their-implications-on-the-response-to-anti-vegf-therapy
#15
Michael Mikhail, Stephen Stewart, Felicia Seow, Ruth Hogg, Noemi Lois
PURPOSE: To determine whether the presence of vitreomacular interface abnormalities (VMIA) in patients with diabetic macular oedema (DMO) modifies the response to ranibizumab. METHODS: Medical records and spectral-domain optical coherence tomography (SD-OCT) scans of consecutive patients with centre-involving DMO initiating therapy with ranibizumab between December 2013 and March 2014 at the Belfast Health and Social Care Trust were reviewed. Patients were identified through an electronic database...
May 19, 2018: Graefe's Archive for Clinical and Experimental Ophthalmology
https://www.readbyqxmd.com/read/29778446/towards-the-interaction-between-calcium-carbide-and-water-during-gas-chromatographic-determination-of-trace-moisture-in-ultra-high-purity-ammonia
#16
Maxim M Trubyanov, Georgy M Mochalov, Sergey S Suvorov, Egor S Puzanov, Anton N Petukhov, Ilya V Vorotyntsev, Vladimir M Vorotyntsev
The current study focuses on the processes involved during the flow conversion of water into acetylene in a calcium carbide reaction cell for the trace moisture analysis of ammonia by reaction gas chromatography. The factors negatively affecting the reproducibility and the accuracy of the measurements are suggested and discussed. The intramolecular reaction of the HOCaCCH intermediate was found to be a side reaction producing background acetylene during the contact of wet ammonia gas with calcium carbide. The presence of the HOCaCCH intermediate among the reaction products is confirmed by an FTIR spectral study of calcium carbide powder exposed to wet gas...
May 16, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/29778241/dual-autonomic-inhibitory-action-of-central-apelin-on-gastric-motor-functions-in-rats
#17
Mehmet Bülbül, Osman Sinen
Centrally administered apelin has been shown to inhibit gastric emptying (GE) in rodents, however, the relevant mechanism has been investigated incompletely. Using male Wistar rats, we investigated the efferent pathways involved in gastroinhibitory action of central apelin. Stereotaxic intracerebroventricular (icv) cannulation, subdiaphragmatic vagotomy (VGX) and/or celiac ganglionectomy (CGX) were performed 7 days prior to the experiments. Apelin-13 was administered (30 nmol, icv) 90 min prior to GE measurement...
July 2018: Autonomic Neuroscience: Basic & Clinical
https://www.readbyqxmd.com/read/29777946/screening-method-for-rapid-classification-of-psychoactive-substances-in-illicit-tablets-using-mid-infrared-spectroscopy-and-pls-da
#18
Leandro S A Pereira, Fernanda L C Lisboa, José Coelho Neto, Frederico N Valladão, Marcelo M Sena
Several new psychoactive substances (NPS) have reached the illegal drug market in recent years, and ecstasy-like tablets are one of the forms affected by this change. Cathinones and tryptamines have increasingly been found in ecstasy-like seized samples as well as other amphetamine type stimulants. A presumptive method for identifying different drugs in seized ecstasy tablets (n=92) using ATR-FTIR (attenuated total reflectance - Fourier transform infrared spectroscopy) and PLS-DA (partial least squares discriminant analysis) was developed...
May 9, 2018: Forensic Science International
https://www.readbyqxmd.com/read/29777933/novel-amidine-derivatives-of-benzanthrone-effect-of-bromine-atom-on-the-spectral-parameters
#19
E M Kirilova, A I Puckins, E Romanovska, M Fleisher, S V Belyakov
Several new substituted amidine derivatives of benzanthrone were synthesized by condensation reaction from 2-bromo-3-aminobenzo[de]anthracen-7-one and appropriate aromatic or aliphatic amides. The novel benzanthrone derivatives were characterized by TLC analysis, NMR, IR, MS, UV/Vis, and fluorescence spectroscopy. The obtained derivatives have yellow or orange fluorescence in organic solvents. The solvent effect on photophysical behaviors of these dyes was investigated, and the results showed that the introduction of a bromine atom causes a blue-shift of the absorption and emission bands and decrease in the fluorescent quantum yield in comparison with unbromated analogues...
May 9, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29777157/transient-metal-centered-states-mediate-isomerization-of-a-photochromic-ruthenium-sulfoxide-complex
#20
Amy A Cordones, Jae Hyuk Lee, Kiryong Hong, Hana Cho, Komal Garg, Martial Boggio-Pasqua, Jeffrey J Rack, Nils Huse, Robert W Schoenlein, Tae Kyu Kim
Ultrafast isomerization reactions underpin many processes in (bio)chemical systems and molecular materials. Understanding the coupled evolution of atomic and molecular structure during isomerization is paramount for control and rational design in molecular science. Here we report transient X-ray absorption studies of the photo-induced linkage isomerization of a Ru-based photochromic molecule. X-ray spectra reveal the spin and valence charge of the Ru atom and provide experimental evidence that metal-centered excited states mediate isomerization...
May 18, 2018: Nature Communications
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