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991.
Scarabino C Lubritto C Proto A Rubino M Fiengo G Marzaioli F Passariello I Busiello G Fortunato A Alfano D Sabbarese C Rogalla D De Cesare N d'Onofrio A Terrasi F 《Isotopes in environmental and health studies》2006,42(2):151-158
Human bones recovered from the archaeological site of Pontecagnano (Salerno, Italy) have been studied to reconstruct the diet of an Etrurian population. Two different areas were investigated, named Library and Sant' Antonio, with a total of 44 tombs containing human skeletal remains, ranging in age from the 8th to the 3rd century B.C. This time span was confirmed by 14C dating obtained using Accelerator Mass Spectrometry (AMS) on one bone sample from each site.Atomic Absorption Spectrometry (AAS) was used to extract information about the concentration of Sr, Zn, Ca elements in the bone inorganic fraction, whilst stable isotope ratio measurements (IRMS) were carried out on bone collagen to obtain the delta13C and delta15N. A reliable technique has been used to extract and separate the inorganic and organic fractions of the bone remains.Both IRMS and AAS results suggest a mixed diet including C3 plant food and herbivore animals, consistent with archaeological indications. 相似文献
992.
Nicola Garofalo Federico Tournier 《Transactions of the American Mathematical Society》2006,358(5):2011-2055
We prove some new properties of the weakly -convex functions recently introduced by Danielli, Garofalo and Nhieu. As an interesting application of our results we prove a theorem of Busemann-Feller-Alexandrov type in the Heisenberg groups , .
993.
We report peculiar velocity quantization phenomena in the classical motion of an idealized 1D solid lubricant, consisting of a harmonic chain interposed between two periodic sliders. The ratio upsilon(c.m.)/upsilon(ext) of the chain center-of-mass velocity to the externally imposed relative velocity of the sliders stays pinned to exact "plateau" values for wide ranges of parameters, such as slider corrugation amplitudes, external velocity, chain stiffness, and dissipation, and is strictly determined by the commensurability ratios alone. The phenomenon is explained by one slider rigidly dragging the kinks that the chain forms with the other slider. Possible consequences of these results for some real systems are discussed. 相似文献
994.
Transition-metal centers are the active sites for a broad variety of biological and inorganic chemical reactions. Notwithstanding this central importance, density-functional theory calculations based on generalized-gradient approximations often fail to describe energetics, multiplet structures, reaction barriers, and geometries around the active sites. We suggest here an alternative approach, derived from the Hubbard U correction to solid-state problems, that provides an excellent agreement with correlated-electron quantum chemistry calculations in test cases that range from the ground state of Fe2 and Fe2- to the addition elimination of molecular hydrogen on FeO+. The Hubbard U is determined with a novel self-consistent procedure based on a linear-response approach. 相似文献
995.
Diana Pendin Rosa Norante Andrea DeNadai Gaia Gherardi Nicola Vajente Emy Basso Nina Kaludercic Cristina Mammucari Cristina Paradisi Tullio Pozzan Andrea Mattarei 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(29):10022-10027
Ca2+ handling by mitochondria is crucial for cell life and the direct measure of mitochondrial Ca2+ concentration in living cells is of pivotal interest. Genetically‐encoded indicators greatly facilitated this task, however they require demanding delivery procedures. On the other hand, existing mitochondria‐targeted synthetic Ca2+ indicators are plagued by several drawbacks, for example, non‐specific localization, leakage, toxicity. Here we report the synthesis and characterization of a new fluorescent Ca2+ sensor, named mt‐fura‐2, obtained by coupling two triphenylphosphonium cations to the molecular backbone of the ratiometric Ca2+ indicator fura‐2. Mt‐fura‐2 binds Ca2+ with a dissociation constant of ≈1.5 μm in vitro. When loaded in different cell types as acetoxymethyl ester, the probe shows proper mitochondrial localization and accurately measures matrix [Ca2+] variations, proving its superiority over available dyes. We describe the synthesis, characterization and application of mt‐fura‐2 to cell types where the delivery of genetically‐encoded indicators is troublesome. 相似文献
996.
We analyze the extension of the well known relation between Brownian motion and the Schrödinger equation to the family of the Lévy processes. We consider a Lévy-Schrödinger equation where the usual kinetic energy operator-the Laplacian-is generalized by means of a selfadjoint, pseudodifferential operator whose symbol is the logarithmic characteristic of an infinitely divisible law. The Lévy-Khintchin formula shows then how to write down this operator in an integro-differential form. When the underlying Lévy process is stable we recover as a particular case the fractional Schrödinger equation. A few examples are finally given and we find that there are physically relevant models-such as a form of the relativistic Schrödinger equation-that are in the domain of the non stable Lévy-Schrödinger equations. 相似文献
997.
Passive mode locking of a diode-pumped Yb(3+):KYF(4) laser is demonstrated using a semiconductor saturable absorber mirror. A high-stability, transform-limited pulse train with a repetition rate of 57 MHz is generated. Solitonlike pulses with maximum average output power of 250 mW, minimum pulse duration of 170 fs, and rms time jitter of 360 fs were obtained. 相似文献
998.
Recent results in EPR-type experiments on singlet photon pairs which establish (a) the non-existence of local hidden variables, (b) the existence of quantum superluminal correlations between the action of independent parts of a measuring device separated by space-like intervals, are interpreted causally within the frame of the stochastic interpretation of quantum mechanics. 相似文献
999.
Summary In this paper is described the application of the vectorial reconstruction to the holographic determination of absolute retardation fringes. The method requires a double-exposure hologram recorded with two reference beams. During the reconstruction process the image emerging from the hologram is viewed through a linear polarizer. Where the polarization direction is parallel to one of the principal stresses, only the corresponding family of absolute retardations is observed. By rotating the polarizer it is possible to observe the fringes over the whole model. The method is demonstrated experimentally using a deep beam centrally loaded.
Paper presented at IV AIAS Conference held in Roma on September 30 – October 2, 1976. 相似文献
Sommario In questa memoria si applica la ricostruzione vettoriale alla determinazione delle frange dei ritardi assoluti. Il metodo richiede l'esecuzione di un ologramma ad esposizione doppia registrato con due raggi di riferimento. In fase di ricostruzione l'immagine emergente dall'ologramma viene osservata attraverso un polarizzatore lineare. Nei punti del modello in cui la direzione di polarizzazione è parallela ad una tensione principale, si osserva la corrispondente famiglia dei ritardi assoluti. Ruotando il polarizzatore è quindi possibile osservare le frange dei ritardi assoluti in tutto il modello. Quale esempio di applicazione si riporta la determinazione delle frange dei ritardi assoluti in una trave corta caricata in mezzeria.
Paper presented at IV AIAS Conference held in Roma on September 30 – October 2, 1976. 相似文献
1000.
We use the reflection of a noble gas (helium) molecular beam to study the superficial reactions of oxygen and carbon monoxide with polycrystalline tantalum. The fraction of the incident beam which is specularly reflected gives direct information on the formation of an oxygen chemisorbed layer and we observed only a single apparent binding state for oxygen chemisorbed on tantalum. The initial value of the sticking coefficient of oxygen on clean polycrystalline tantalum is 0.86, decreasing rapidly during the formation of a chemisorbed layer. The specularly reflected fraction of the incident beam is also modified by the chemisorption of carbon monoxide and this modification would confirm the dissociative character of the CO chemisorption on tantalum. The influence of the partial pressure of CO on the temperature at which the surface is completely covered by the products of the dissociative chemisorption of CO shows that the coverage becomes equal to unity at temperatures at which the solubility limit of CO is attained and tantalum carbide is formed. 相似文献