Quantum curves and q-deformed Painlevé equations

Letters in Mathematical Physics - We propose that the grand canonical topological string partition functions satisfy finite-difference equations in the closed string moduli. In the case of genus...     

Atmospheric tides and periodic variations in the precipitation field

Summary The analysis of daily precipitation data at many weather stations in Alpes and Po Valley gives evidence of a “tidal” influence from luni-solar gravitational fields. Periodicities in the 13–15 and 27–30 day time interval have been frequently extracted from data series (ENEL data: 1970–1981 years; SMR data: 1961–1980 years), by using distinct methods. The tidal influence does not appear to be strictly constant with time, as the possible result of a modulation effect of luni-solar cycles having similar periods. Time variations of daily precipitation data as a function of some particular cycles show that gravitational tides affect heavy rainfalls more than mean precipitation values. The different contribution of “semi-monthly” oscillations with season underlines a more distinguishable regime of vertical motions in Winter with respect to Summer. In investigating joint effects of different luni-solar components, the inverse Fourier transform method points out superimposed influences in correspondence to some years (1966 and 1976), climatologically very interesting, and this might assist in the previsional studies of extreme precipitation.

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Riassunto I risultati delle analisi dei dati giornalieri di precipitazione, raccolti presso molte stazioni dell'arco alpino e della pianura padana (dati ENEL: anni 1970–1981 e dati SMR: anni 1961–1980) mettono in mostra un'influenza ?mareale? dei campi gravitazionali luni-solari. Anche utilizzando metodi distinti, è solitamente evidenziata la presenza di componenti periodiche nelle finestre temporali di 13–15 e 27–30 giorni. L'effetto mareale non appare rigidamente costante nel tempo, potendo risultare dalla modulazione di cicli luni-solari aventi periodi simili. Le variazioni nel tempo dei dati giornalieri di precipitazione in funzione di alcuni cicli particolari mostrano che l'influenza mareale ha un effetto maggiore sulle precipitazioni piú forti che non sui valori medi di precipitazione. Il diverso contributo di componenti ?semi-mensili? con la stagione sta ad indicare che l'azione di marea è meglio identificabile in inverno che non in estate. Nelle indagini sugli effetti congiunti di differenti componenti luni-solari, il metodo dell'antitrasformata di Fourier rivela influenze sovrapposte nel campo delle precipitazioni soprattutto in corrispondenza di alcuni anni particolarmente interessanti sotto il profilo climatologico (anni 1966 e 1976), e in tal senso questo metodo può essere utile in studi previsionali delle precipitazioni piú forti.

     

Mesoporous materials for the retention and separation of haloacetic acids

Summary Mesoporous silica-based materials have been synthesized and studied for applications in the environmental field. Haloacetic acids have been chosen as test compounds since they are byproducts of disinfection processes of water for human consumption. For this purpose mesoporous materials have been synthesized in acid, basic or neutral conditions. The effect of composition and synthesis conditions of mesoporous materials on their retention properties have been studied. The retention mechanism has also been elucidated in term of electrostatic interactions and as a function of the residual surfactant content in the materials. Presented at Balaton Symposium '01 on High-Performance Separation Methods, Siófok, Hungary, September 2–4, 2001     

Enhanced mass resolution method development, validation and assay application to support preclinical studies of a new drug candidate

A very highly sensitive and highly selective liquid chromatographic/tandem mass spectrometric (LC/MS/MS) method was developed to evaluate and quantify a new drug candidate in different biological matrices. Following a simple plasma protein precipitation using acetonitrile, the post-treatment samples were analyzed on a C18 column interfaced with a new generation of triple-quadrupole mass spectrometer. The recently introduced triple-quadrupole mass spectrometer, the TSQ Quantum Ultra, with enhanced mass-resolution capability, demonstrated improved sensitivity (0.05 ng/mL), coupled with suitable accuracy and precision, over a broad linear dynamic range (0.05-1000 ng/mL). A comparison of the assay performance data (dynamic range, calibration curve equation, precision and accuracy) of the enhanced resolution method against a unit resolution method under optimized conditions showed the performance improvement of the enhanced mass resolution method for bioanalytical high-throughput applications. The enhanced mass resolution method herein described was successfully applied to the evaluation of the pharmacokinetic profile of a new drug candidate in rat, rabbit and dog plasma samples.     

Development of a simple and reliable accurate mass liquid chromatography/electrospray ionization mass spectrometry method for high-resolution accurate mass determinations of new drug entities on a triple quadrupole mass spectrometer

Accurate mass measurements are used to determine the elemental composition and formulae of molecules to confirm their identity or to assist in their characterization. Currently, the most widely used techniques for measuring exact masses employ magnetic sector instruments, Fourier transform ion cyclotron resonance mass spectrometers and lower resolution instruments such as time-of-flight (TOF) and quadrupole-TOF. This paper reports the accurate mass measurement using a triple quadrupole mass spectrometer. Indeed, the recently introduced triple quadrupole mass spectrometer, with unique enhanced mass-resolution capability, has demonstrated simple data acquisition methods and requires few experiments to measure exact masses with accuracy and determines elemental compositions of both protonated and deprotonated molecules. All the accurate mass measurements were performed using both positive and negative electrospray ionization in enhanced mass-resolution mode (peak width of 0.1 Th FWMH). Several new drug entities were investigated as simulated unknowns and analyzed by means of an accurate mass liquid chromatography/electrospray ionization mass spectrometry (AM-LC/ESI-MS) method. The accurate mass measurements resulted in only one proposed elemental composition for all tested compounds, using reasonable elemental limits and mass tolerance for the calculation. Moreover, all the experimentally determined accurate mass measurements gave satisfactory results in terms of accuracy (lower than 5 ppm).