Search results for "Fourier transform"
showing 10 items of 1138 documents
Quantum Algorithm for Distribution-Free Junta Testing
2019
Inspired by a recent classical distribution-free junta tester by Chen, Liu, Serverdio, Sheng, and Xie (STOC’18), we construct a quantum tester for the same problem with complexity \(O(k/\varepsilon )\), which constitutes a quadratic improvement.
Aggregation Kinetics of Bovine Serum Albumin Studied by FTIR Spectroscopy and Light Scattering
2003
To investigate which type of structural and conformational changes is involved in the aggregation processes of bovine serum albumin (BSA), we have performed thermal aggregation kinetics in D(2)O solutions of this protein. The tertiary conformational changes are followed by Amide II band, the secondary structural changes and the formation of beta-aggregates by the Amide I' band and, finally, the hydrodynamic radius of aggregates by dynamic light scattering. The results show, as a function of pD, that: tertiary conformational changes are more rapid as pD increases; the aggregation proceeds through formation of ordered aggregates (oligomers) at pD far from the isoelectric point of the protein;…
Conformational substates and dynamic properties of carbonmonoxy hemoglobin.
2003
Heme pocket dynamics of human carbonmonoxy hemoglobin (HbCO) is studied by Fourier transform infrared spectroscopy. The CO stretching band at various temperatures in the interval 300-10 K is analyzed in terms of three taxonomic A substates; however, in HbCO the band attributed to the A(1) taxonomic substate accounts for approximately 90% of the total intensity in the pH range 8.8-4.5. Two different regimes as a function of temperature are observed: below 160 K, the peak frequency and the bandwidth of the A(1) band have constant values whereas, above this temperature, a linear temperature dependence is observed, suggesting the occurrence of transitions between statistical substates within th…
Conformational investigation of alpha,beta-dehydropeptides. VIII. N-acetyl-alpha,beta-dehydroamino acid N'-methylamides: conformation and electron de…
2009
The Fourier transform infrared spectra are analyzed in the regions of Vs(N-H), amide I, amide II and Vs(C alpha = C beta) bands for a series of Ac-delta Xaa-NHMe, where delta Xaa = delta Ala, (Z)-delta Abu, (Z)-delta Leu, (Z)-delta Phe and delta Val, to determine the predominant solution conformation of these alpha,beta-dehydropeptide-related molecules and the electron distribution perturbation in their amide bonds. The measurements were performed in dichloromethane (DCM). To confirm and rationalize the assignments, the spectra of the respective series of saturated Ac-Xaa-NHMe, recorded in DCM, and the spectra of these two series of unsaturated and saturated compounds, recorded in acetonitr…
Thermal aggregation of beta-lactoglobulin in presence of metal ions.
2007
In this work, we report a study of the effects of zinc and copper ions on the heat-induced aggregation of beta-lactoglobulin (BLG). Kinetics investigations on aggregates growth by light scattering measurements and on secondary structure changes by FTIR absorption measurements show the different role played by the two metals during the whole process. In particular, the presence of zinc in solution promotes the formation of aggregates of BLG at a lower temperature than copper. Then, at fixed temperature, formation of a large amount of aggregates, of large dimension, is observed for Zn-BLG in shorter time; on the contrary, the presence of copper in solution does not affect the aggregation proc…
The skeleton of the staghorn coral Acropora millepora: molecular and structural characterization.
2014
15 pages; International audience; The scleractinian coral Acropora millepora is one of the most studied species from the Great Barrier Reef. This species has been used to understand evolutionary, immune and developmental processes in cnidarians. It has also been subject of several ecological studies in order to elucidate reef responses to environmental changes such as temperature rise and ocean acidification (OA). In these contexts, several nucleic acid resources were made available. When combined to a recent proteomic analysis of the coral skeletal organic matrix (SOM), they enabled the identification of several skeletal matrix proteins, making A. millepora into an emerging model for biomi…
The test skeletal matrix of the black sea urchin Arbacia lixula
2015
11 pages; International audience; In the field of biomineralization, the past decade has been marked by the increasing use of high throughput techniques, i.e. proteomics, for identifying in one shot the protein content of complex macromolecular mixtures extracted from mineralized tissues. Although crowned with success, this approach has been restricted so far to a limited set of key-organisms, such as the purple sea urchin Strongylocentrotus purpuratus, the pearl oyster or the abalone, leaving in the shadow non-model organisms. As a consequence, it is still unknown to what extent the calcifying repertoire varies, from group to group, at high (phylum, class), median (order, family) or low (g…
Classification of pumpkin seed oils according to their species and genetic variety by attenuated total reflection Fourier-transform infrared spectros…
2011
Attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR), followed by multivariate treatment of the spectral data, was used to classify seed oils of the genus Cucurbita (pumpkins) according to their species as C. maxima, C. pepo, and C. moschata. Also, C. moschata seed oils were classified according to their genetic variety as RG, Inivit C-88, and Inivit C-2000. Up to 23 wavelength regions were selected on the spectra, each region corresponding to a peak or shoulder. The normalized absorbance peak areas within these regions were used as predictors. Using linear discriminant analysis (LDA), an excellent resolution among all categories concerning both Cucurbita species a…
Multidimensional dyadic Kurzweil–Henstock- and Perron-type integrals in the theory of Haar and Walsh series
2015
Abstract The problem of recovering the coefficients of rectangular convergent multiple Haar and Walsh series from their sums, by generalized Fourier formulas, is reduced to the one of recovering a function (the primitive) from its derivative with respect to the appropriate derivation basis. Multidimensional dyadic Kurzweil–Henstock- and Perron-type integrals are compared and it is shown that a Perron-type integral, defined by major and minor functions having a special continuity property, solves the coefficients problem for series which are convergent everywhere outside some uniqueness sets.
Uniform estimates for the local restriction of the Fourier transform to curves
2013
We prove sharp estimates, with respect to the ane arclength measure, for the restriction of the Fourier transform to a class of curves in R^d that includes curves of nite type. This measure possesses certain invariance and mitigation properties which are important in establishing uniform results. Peer reviewed