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941.
Laura Găvruţa 《Applied and Computational Harmonic Analysis》2012,32(1):139-144
Frames in Hilbert spaces are a redundant set of vectors which yield a representation for each vector in the space. In the present paper, we give a generalization of frames, which allows, in a stable way, to reconstruct elements from the range of a linear and bounded operator in a Hilbert space. 相似文献
942.
943.
MV Kondaurova TR Bergeson LC Dilley 《The Journal of the Acoustical Society of America》2012,132(2):1039-1049
Recent studies have demonstrated that mothers exaggerate phonetic properties of infant-directed (ID) speech. However, these studies focused on a single acoustic dimension (frequency), whereas speech sounds are composed of multiple acoustic cues. Moreover, little is known about how mothers adjust phonetic properties of speech to children with hearing loss. This study examined mothers' production of frequency and duration cues to the American English tense/lax vowel contrast in speech to profoundly deaf (N?=?14) and normal-hearing (N?=?14) infants, and to an adult experimenter. First and second formant frequencies and vowel duration of tense (/i/,?/u/) and lax (/I/,?/?/) vowels were measured. Results demonstrated that for both infant groups mothers hyperarticulated the acoustic vowel space and increased vowel duration in ID speech relative to adult-directed speech. Mean F2 values were decreased for the /u/ vowel and increased for the /I/ vowel, and vowel duration was longer for the /i/, /u/, and /I/ vowels in ID speech. However, neither acoustic cue differed in speech to hearing-impaired or normal-hearing infants. These results suggest that both formant frequencies and vowel duration that differentiate American English tense/lx vowel contrasts are modified in ID speech regardless of the hearing status of the addressee. 相似文献
944.
Debbie?Leung Laura?Mancinska William?MatthewsEmail author Maris?Ozols Aidan?Roy 《Communications in Mathematical Physics》2012,311(1):97-111
It is known that the number of different classical messages which can be communicated with a single use of a classical channel with zero probability of decoding error can sometimes be increased by using entanglement shared between
sender and receiver. It has been an open question to determine whether entanglement can ever increase the zero-error communication
rates achievable in the limit of many channel uses. In this paper we show, by explicit examples, that entanglement can indeed
increase asymptotic zero-error capacity, even to the extent that it is equal to the normal capacity of the channel. 相似文献
945.
Csar Leyva-Porras María Zenaida Saavedra-Leos Laura Araceli Lpez-Martinez Vicente Espinosa-Solis Yolanda Tern-Figueroa Alberto Toxqui-Tern Isaac Compen-Martínez 《Molecules (Basel, Switzerland)》2021,26(18)
The drying of fruit juices has advantages such as easy handling of powders, reduction in volume, and preservation of the characteristics of the fruit. Thus, in this work, the effect of the spray drying conditions of strawberry juice (SJ) with maltodextrin (MX) as a carrying agent on the microencapsulation of bioactive compounds and physicochemical properties was studied. The content of phenolic compounds and antioxidant activity showed higher values at low concentrations of MX, while the effect of drying temperature was negligible. The thermal characterization showed that the low molecular weight sugars in the juice decreased the glass transition temperature (Tg). The morphological analysis by scanning electron microscopy (SEM) indicated that at low concentrations of MX, the particles agglomerated, while at intermediate and high concentrations, the particles were observed as well separated. Through microstructural analysis by X-ray diffraction (XRD), the presence of amorphous state was confirmed in all the samples, which is beneficial for preventing chemical and biochemical reactions, and promoting the conservation of the microencapsulated bioactive compounds. 相似文献
946.
We study the synchronization of the pedestrians motion with the lateral motion of slender footbridges, which attracted the
attention of researchers mainly after the Millennium Bridge well known event. We consider a bridge-pedestrians model developed
by Strogatz et al. To better understand some aspects of the underlying mechanical phenomena and to increase the agreement
of the model results to the effective behaviour of the walkers (as observed during the Millennium Bridge’s opening day and
during Arup’s tests on site) we have introduced some modifications to the model and we have performed extensive parametric
investigations, supported by many numerical simulations. Our approach is therefore computational, by means of a self-made
code. This permits to highlight the parameters which mainly affect the trigger and the development of the phenomenon of synchronous
lateral excitation, thus allowing a good understanding of the physical event and an evaluation of the engineering reliability
of the Strogatz et al. model. 相似文献
947.
V Sanz-Nebot I Toro R Bergés R Ventura J Segura J Barbosa 《Journal of mass spectrometry : JMS》2001,36(6):652-657
The aim of this work was to develop a method for the characterization and determination of diuretics in human urine samples by liquid chromatography (LC) coupled to pneumatically assisted electrospray ionization (ES) mass spectrometry (MS). The diuretics studied were substances forbidden by the IOC such as trichlormethiazide, furosemide, canrenoic acid, benzthiazide, bendroflumethiazide, bumetanide, etacrynic acid and spironolactone. For this purpose, the operational parameters of electrospray, such as counter electrode voltage, capillary voltage, sample cone voltage and source temperature, were optimized in order to obtain the best signal stability and the highest sensitivity for the greatest number of diuretic agents. The optimized separation method was successfully coupled with the MS system to analyze the above-mentioned diuretics extracted from spiked urine samples by a liquid extraction and clean-up procedure at basic pH, using ethyl acetate as solvent and the salting-out effect (NaCl). The mass spectra obtained provide adequate information for identification purposes. Positive urine samples obtained from athletes were also analyzed. The presence of these substances in human urine was confirmed by this method, making LC/ES-MS an analytical tool to be considered in the area of antidoping control. 相似文献
948.
Laura Scaccianoce Neil Feeder Simon J. Teat Elisabeth A. Marseglia Andrew C. Grimsdale Andrew B. Holmes 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(10):1277-1279
Two polymorphs, α and γ, of the title compound, C22H20N2O2, have been characterized by means of single‐crystal synchrotron X‐ray diffraction. In the α form, the molecules pack in a herring‐bone fashion, linked via weak C—H?N intermolecular interactions (H?N 2.58 Å). In the γ form, the molecules are arranged in nearly planar sheets, which form a network held together by intermolecular hydrogen bonds of the type C—H?O (H?O 2.49 Å) and C—H?N (H?N 2.50 Å). The stacking distance between the sheets is 3.40 Å. 相似文献
949.
Laura De Carli 《Israel Journal of Mathematics》2000,118(1):15-27
In this paper we prove a unique continuation theorem for elliptic operators of the formP(D)+V(x), whereP(D) has orderm≥2 and simple complex characteristics, andV(x)∈L
n/m
(R
n
). To prove our main theorem we use a restriction theorem for the Fourier transform to manifolds of codimension 2. 相似文献
950.
Alberto Ceccon Annalisa Bisello Laura Crociani Alessandro Gambaro Paolo Ganis Francesco Manoli Saverio Santi Alfonso Venzo 《Journal of organometallic chemistry》2000,600(1-2):94-111
The Rh(COD) and Ir(COD) homobimetallic complexes of s-indacene-diide, 2,6-dimethyl-s-indacene-diide, as-indacene-diide, and 2,7-dimethyl-as-indacene-diide have been synthesized from the di-lithium salts of the dianions and metal dimers [M(μ-Cl)L2]2 (M = Rh, Ir; L2 = COD, NBD, (ethylene)2, (CO)2 as mixtures of syn and anti isomers. The syn/anti ratio depends on the nature of the ancillary ligands at the metal and on the s or as geometry of the bridging ligand. In the reaction of the 2,7-dimethyl-as-indacene-diide-[M(COD)]2 species with CO, the higher reactivity of the syn isomers has been justified on the basis of a greater instability of the ground state due to steric interactions between the COD groups. Bis-η1 metal-bonded intermediates have been identified in the carbonylation of iridium derivatives; on the other hand, the formation of the bis-η5 mixed complexes syn and anti-{2,7-dimethyl-as-indacene-diide-[Rh(COD)][Rh(CO)2]} and their reactivity strongly support the existence of metal---metal interaction in the rhodium derivatives. 相似文献