Multidimensional approach

The fitting parameters in the transfomi method are properties related to the two potential energy surfaces that define die electronic resonance. These curves are obtained when the two hypersurfaces are cut along theyth nomial mode coordinate. In order of increasing theoretical sophistication these properties are (i) the relative position of their minima (often called the displacement parameters), (ii) the force constant of the vibration (its frequency), (iii) nuclear coordinate dependence of the electronic transition moment and (iv) the issue of mode mixing upon excitation—known as the Duschinsky effect—requiring a multidimensional approach. 

Although SFE and SFC share several common features, including the use of a superaitical fluid as the solvent and similar instrumentation, their goals are quite distinct. While SFE is used mainly for the sample preparation step (extraction), SFC is employed to isolate (chr-omatography) individual compounds present in complex samples (11 -15). Both techniques can be used in two different approaches off-line, in which the analytes and the solvent are either vented after analysis (SFC) or collected (SFE), or on-line coupled with a second technique, thus providing a multidimensional approach. Off-line methods are slow and susceptible to solute losses and contamination the on-line coupled system makes possible a deaease in the detection limits, with an improvement in quantification, while the use of valves for automation results in faster and more reproducible analyses (16). The off-line... 

Tleugabulova, D. Falcon, V., and Penton, E., Physico-chemical characterization of recombinant hepatitis B surface antigen by a multidimensional approach, /. Chromatogr. A, 845, 171, 1999. 

Table 7.85 gives an overview of the main multidimensional chromatographies. Multidimensional success stories are GC-GC, LC-LC and LC-CE. Various multidimensional approaches may be distinguished ... 

Danzer K (1995a) Calibration - a multidimensional approach. Fresenius J Anal Chem 351 3... 

While recognizing these limitations, such isopleths are useful, however, in examining the differing responses of various locations within an air basin to control of VOC and NOx. Since the air mass that starts upwind in the morning traverses the air basin during the day, a multidimensional approach to ozone control is clearly needed. Isopleths characteristic of different locations in an air basin such as those in Fig. 16.16 demonstrate that a combination of VOC and NOx control is essential if air quality throughout a major air basin is to improve consistently (although not necessarily by equal amounts) in all locations. 

To obtain a comprehensive analysis of carbohydrate mixtures from biological matrices that display a high degree of compositional and structural heterogeneity, a multidimensional approach is required. The combination into a so-called hyphenated system, of liquid chromatography (LC) or CE with MS provides the advantage of selective and efficient separation with the mass specificity, sensitivity, and structural information gained from MS. 

Fisher BE, Rinehart S. Stress, arousal, psychopathology and temperament a multidimensional approach to sleep disturbance in children. Personal Individ Diff 1990 11(5) 431—438. 

Yau, O.H.M. and Chan, C.F. (1990) Hong Kong as a travel destination in South-East Asia A multidimensional approach. Tourism Management 11 (2), 123-132. 

Warner and co-workers justify the elaborate optical/detection system and the time commitment required per analysis on the basis of the additional sensitivity available using fluorescence detection, and on the multidimensional CD information available. For applications in which two, or more CD active fluorophores may be present, the ability to provide both an excitation and emission FDCD profile for the sample may allow differentiation of the individual components without pre-separation. Replacement of the mechanical mechanism for prism movement with an electro-optical device may improve both the SNR and reduce the time required per sample. These improvements will greatly facilitate general application of this multidimensional approach to FDCD measurements. 

Recent trends in Se speciation include the use of multidimensional approaches based on combinations of the above-mentioned techniques, the fractionation of... 

J. Szpunar, R. Lobinski, Multidimensional approaches in biochemical speciation analysis, Anal. Bioanal. Chem., 373 (2002), 404 D411. 

Malamuth, N.M. A Multidimensional Approach to Sexual Aggression Combining Measures of Past Behavior and Present Likelihood. Annals of the New York Academy of Sciences 528 (1998) 123-132. 

Vander Greef J, Niessen WMA, Tjaden UR. Liquid chromatography-mass spectrometry. The need for a multidimensional approach. J Chromatogr 1989 477 5-20. 

Various methods were evaluated for the targeted proteomics of human growth hormone (hGH) in human plasma [111]. hGH was spiked in plasma 10-fold above natural level ( 16 pg/pl). Iiutially, the full plasma proteome was reduced, alkylated, and digested prior to LC-MS via DDA on an ion-trap instrument. hGH could be identified from its T, peptide. Next, the plasma proteome was fractionated by RPLC and GE prior to digestion and LC-MS analysis. hGH could be identified with higher confidence. Finally, an LCxLC-MS approach was apphed, which enabled hGH identification from five tryptic peptides. An important conclusion was that hGH could be detected in a complex sample at the low femtomole level among proteins that were 40,000 x more abundant. The results show that a multidimensional approach may be taken for targeted proteomics and quantitative protein bioanalysis. 

Industrial electrochemical cells, for which the local current distribution must be precisely determined, mainly involve multidimensional approaches. The electrokinetic problem is then solved using specific finite element codes such as COMSOL or Flux-Expert . 

The two examples discussed show the bioanalytical applicability of LC/MS, both in qualitative analysis and in target compound analysis. Although the moving belt interface owing to its El capabilities is ideally suited for the identification of unknown compounds and is used often for that purpose, identification problems can sometimes also be solved with thermospray LC/MS, for instance by applying repeller-induced fragmentation, and LC/MS/MS. The PSS approach is an example that indicates that LC/MS still can be improved. A more elaborate discussion on the so-called multidimensional approaches in LC/MS is given elsewhere (14). 

The study of HRQOL requires a multidimensional approach. Assessments must include components that evaluate, at a minimum, the health concepts of physical functioning, social and role functioning, mental health, and perception of general health. In addition, the full continuum of these concepts must be included, from the most limited to the healthiest. Approaches to capture HRQOL data include the self-administered questionnaire, personal interview, telephone interview, observation, and postal survey. The assessment instruments must possess acceptable reliability, validity, and sensitivity, and the investigators and the participants must accept them. Psychometrics... 

Characterizing sleep in children with autism spectrum disorders a multidimensional approach. Sleep 28 1559-1567. 

Thus petroleum analysis is a complex subject involving a variety of techniques, some of which have been mentioned above. But no single technique should supercede the other. Petroleum analysis is a complex discipline that needs a multidimensional approach. And the explanation of the data that are obtained requires adequate interpretation. 

If one ignores polarization effects, the ideal experimental data for the transient emission spectrum of a molecule would be a high resolution three dimensional plot of emission-intensity versus emission-wavelength and delay time after molecular excitation. Most published transient emission data, however, are of the form integrated emission intensity over all emission-wavelengths versus delay time. These data, obviously, have less useful information than the multidimensional approach. 

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