Insight into resolution enhancement in generalized two-dimensional correlation spectroscopy

Generalized two-dimensional correlation spectroscopy (2D-COS) can be used to enhance spectral resolution in order to help differentiate highly overlapped spectral bands. Despite the numerous extensive 2D-COS investigations, the origin of the 2D spectral resolution enhancement mechanism(s) is not completely understood. In the work here, we studied the 2D-COS of simulated spectra in order to develop new insights into the dependence of 2D-COS spectral features on the overlapping band separations, their intensities and bandwidths, and their band intensity change rates. We found that the features in the 2D-COS maps that are derived from overlapping bands were determined by the spectral normalized half-intensities and the total intensity changes of the correlated bands. We identified the conditions required to resolve overlapping bands. In particular, 2D-COS peak resolution requires that the normalized half-intensities of a correlating band have amplitudes between the maxima and minima of the normalized half-intensities of the overlapping bands. © 2013 Society for Applied Spectroscopy

Reliability and validity of the adapted Greek version of scoliosis research society – 22 (SRS-22) questionnaire

<p>Abstract</p> <p>Background</p> <p>The SRS-22 is a valid instrument for the assessment of the health related quality of life of patients with Idiopathic scoliosis. The SRS-22 questionnaire was developed in USA and has been widely used in the English speaking countries. Recently it has been translated and validated in many other languages. The purpose of this study is to evaluate the reliability and validity of the adapted Greek version of the refined Scoliosis Research Society-22 Questionnaire.</p> <p>Methods</p> <p>Following the steps of cross – cultural adaptation the adapted Greek version of the SRS-22 questionnaire and a validated Greek version of the SF-36 questionnaire were mailed to 68 patients treated surgically for Idiopathic Scoliosis. 51 out of the 68 patients returned the 1^stset of questionnaires, while a second set was emailed to 30 randomly selected patients of the first time responders. 20 out of the 30 patients returned the 2^ndset. The mean age at the time of operation was16,2 years and the mean age at the time of evaluation was 21,2 years. Descriptive statistics for content analysis were calculated. Reliability assessment was determined by estimating Cronbach's α and intraclass correlation coefficient (ICC) respectively. Concurrent validity was evaluated by comparing SRS-22 domains with relevant domains in the SF-36 questionnaire using Pearson's Correlation Coefficient (r).</p> <p>Results</p> <p>The calculated Cronbach's α of internal consistency for three of the corresponding domains (pain 0.85; mental health 0.87; self image 0.83) were very satisfactory and for two domains (function/activity 0.72 and satisfaction 0.67) were good. The ICC of all domains of SRS-22 questionnaire was high (ICC>0.70), demonstrating very satisfactory or excellent test/retest reproducibility. Considering concurrent validity all correlations were found to be statistically significant at the 0.01 level among related domains and generally demonstrated high correlation coefficient.</p> <p>Conclusion</p> <p>The adapted Greek version of the SRS-22 questionnaire is valid and reliable and can be used for the assessment of the outcome of the treatment of the Greek speaking patients with idiopathic scoliosis.</p

Construction and analysis of causally dynamic hybrid bond graphs

Engineering systems are frequently abstracted to models with discontinuous behaviour (such as a switch or contact), and a hybrid model is one which contains continuous and discontinuous behaviours. Bond graphs are an established physical modelling method, but there are several methods for constructing switched or ‘hybrid’ bond graphs, developed for either qualitative ‘structural’ analysis or efficient numerical simulation of engineering systems. This article proposes a general hybrid bond graph suitable for both. The controlled junction is adopted as an intuitive way of modelling a discontinuity in the model structure. This element gives rise to ‘dynamic causality’ that is facilitated by a new bond graph notation. From this model, the junction structure and state equations are derived and compared to those obtained by existing methods. The proposed model includes all possible modes of operation and can be represented by a single set of equations. The controlled junctions manifest as Boolean variables in the matrices of coefficients. The method is more compact and intuitive than existing methods and dispenses with the need to derive various modes of operation from a given reference representation. Hence, a method has been developed, which can reach common usage and form a platform for further study

Rain-induced turbulence and air-sea gas transfer

Author Posting. © American Geophysical Union, 2009. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 114 (2009): C07009, doi:10.1029/2008JC005008.Results from a rain and gas exchange experiment (Bio2 RainX III) at the Biosphere 2 Center demonstrate that turbulence controls the enhancement of the air-sea gas transfer rate (or velocity) k during rainfall, even though profiles of the turbulent dissipation rate ɛ are strongly influenced by near-surface stratification. The gas transfer rate scales with ɛ inline equation for a range of rain rates with broad drop size distributions. The hydrodynamic measurements elucidate the mechanisms responsible for the rain-enhanced k results using SF6 tracer evasion and active controlled flux technique. High-resolution k and turbulence results highlight the causal relationship between rainfall, turbulence, stratification, and air-sea gas exchange. Profiles of ɛ beneath the air-sea interface during rainfall, measured for the first time during a gas exchange experiment, yielded discrete values as high as 10−2 W kg−1. Stratification modifies and traps the turbulence near the surface, affecting the enhancement of the transfer velocity and also diminishing the vertical mixing of mass transported to the air-water interface. Although the kinetic energy flux is an integral measure of the turbulent input to the system during rain events, ɛ is the most robust response to all the modifications and transformations to the turbulent state that follows. The Craig-Banner turbulence model, modified for rain instead of breaking wave turbulence, successfully predicts the near-surface dissipation profile at the onset of the rain event before stratification plays a dominant role. This result is important for predictive modeling of k as it allows inferring the surface value of ɛ fundamental to gas transfer.This work was funded by a generous grant from the David and Lucile Packard Foundation and the Lamont-Doherty Earth Observatory Climate Center. Additional funding was provided by the National Science Foundation (OCE-05-26677) and the Office of Naval Research Young Investigator Program (N00014-04-1-0621)

Ricin B chain targeted to the endoplasmic reticulum of tobacco protoplasts is degraded by a CDC48- and vacuole-independent mechanism

The B chain of ricin was expressed and delivered to the endoplasmic reticulum of tobacco protoplasts where it disappeared with time in a manner consistent with degradation. This turnover did not occur in the vacuoles or upon secretion. Indeed, several lines of evidence indicate that, in contrast to the turnover of endoplasmic reticulum-targeted ricin A chain in the cytosol, the bulk of expressed ricin B chain was degraded in the secretory pathway