A Multilaboratory Comparison of Calibration Accuracy and the Performance of External References in Analytical Ultracentrifugation

Analytical ultracentrifugation (AUC) is a first principles based method to determine absolute sedimentation coefficients and buoyant molar masses of macromolecules and their complexes, reporting on their size and shape in free solution. The purpose of this multi-laboratory study was to establish the precision and accuracy of basic data dimensions in AUC and validate previously proposed calibration techniques. Three kits of AUC cell assemblies containing radial and temperature calibration tools and a bovine serum albumin (BSA) reference sample were shared among 67 laboratories, generating 129 comprehensive data sets. These allowed for an assessment of many parameters of instrument performance, including accuracy of the reported scan time after the start of centrifugation, the accuracy of the temperature calibration, and the accuracy of the radial magnification. The range of sedimentation coefficients obtained for BSA monomer in different instruments and using different optical systems was from 3.655 S to 4.949 S, with a mean and standard deviation of (4.304 ± 0.188) S (4.4%). After the combined application of correction factors derived from the external calibration references for elapsed time, scan velocity, temperature, and radial magnification, the range of s-values was reduced 7-fold with a mean of 4.325 S and a 6-fold reduced standard deviation of ± 0.030 S (0.7%). In addition, the large data set provided an opportunity to determine the instrument-to-instrument variation of the absolute radial positions reported in the scan files, the precision of photometric or refractometric signal magnitudes, and the precision of the calculated apparent molar mass of BSA monomer and the fraction of BSA dimers. These results highlight the necessity and effectiveness of independent calibration of basic AUC data dimensions for reliable quantitative studies

A multilaboratory comparison of calibration accuracy and the performance of external references in analytical ultracentrifugation.

Analytical ultracentrifugation (AUC) is a first principles based method to determine absolute sedimentation coefficients and buoyant molar masses of macromolecules and their complexes, reporting on their size and shape in free solution. The purpose of this multi-laboratory study was to establish the precision and accuracy of basic data dimensions in AUC and validate previously proposed calibration techniques. Three kits of AUC cell assemblies containing radial and temperature calibration tools and a bovine serum albumin (BSA) reference sample were shared among 67 laboratories, generating 129 comprehensive data sets. These allowed for an assessment of many parameters of instrument performance, including accuracy of the reported scan time after the start of centrifugation, the accuracy of the temperature calibration, and the accuracy of the radial magnification. The range of sedimentation coefficients obtained for BSA monomer in different instruments and using different optical systems was from 3.655 S to 4.949 S, with a mean and standard deviation of (4.304 ± 0.188) S (4.4%). After the combined application of correction factors derived from the external calibration references for elapsed time, scan velocity, temperature, and radial magnification, the range of s-values was reduced 7-fold with a mean of 4.325 S and a 6-fold reduced standard deviation of ± 0.030 S (0.7%). In addition, the large data set provided an opportunity to determine the instrument-to-instrument variation of the absolute radial positions reported in the scan files, the precision of photometric or refractometric signal magnitudes, and the precision of the calculated apparent molar mass of BSA monomer and the fraction of BSA dimers. These results highlight the necessity and effectiveness of independent calibration of basic AUC data dimensions for reliable quantitative studies

Effectivity of using iPad-based alternative and augmentative communication to facilitate initiating, requesting and commenting of children with Autism Spectrum Disorder : a descriptive systematic review

The study aimed to know how different studies suggested the effectiveness of high-tech alternative and augmentative communication (AAC) device especially for school-aged children with autism spectrum disorder (ASD) during requesting, commenting and responding to difference social contexts. Seven (7) single-case studies were used in the systematic review based on the following selection criteria: 1) participants should have ASD, 2) should be in pediatric age, and 3) should have impairment in social skills. Results of the studies suggested that the use of iPad-based AAC helped in aiding and facilitating different social skills. Some of the participants in each study preferred the use of a low-tech AAC device due to prolonged exposure to it prior to the study and due to age which made a slow progress and acquisition of necessary skills for the use of a iPad-based AAC. The use of an iPad-based AAC was effective in facilitating initiating, requesting and commenting similar to using PECS and other AAC modalities

Determinants of franchising decision among selected Filipino franchisees

Franchising has become a widely recognized business model nowadays due to the perceived success it has for both franchisors and franchisees. It has provided individuals, with or without business background, opportunities for self employment and investment. However, despite its success and implications to local business growth in the economy, little literature on franchising has been made in the context of Philippine franchise businesses. This study aimed to determine the factors that influenced the interest and decision of purchasing a franchise for both potential and existing franchisees. Using the Pearson correlation, OLS regression, and ANOVA, it was found that operational benefits provided by franchisors, advices from peers and management consultants positively influence the purchase intent of potential franchisees no longer hold true for existing franchisees with the underlying factor being the dissatisfaction in the franchisee-franchisor relationship. Through the results of the study we point out the importance of maintaining good relationship between franchisee and franchisors by providing continuous training support, franchisee empowerment and other franchise benefits by the franchisor. Franchisors can also collaborate with banks in creating franchise loans to franchisees. Potential franchisees, on the other hand, must manage expectations by thoroughly inquiring franchisors as well as consulting with experienced franchisees. Improvements in the legal aspects for the protection of key participants in the industry are also influential in strengthening the industry. The findings of this study provide influential propositions to franchisors, franchisees, and legal entities for the continuous development of the franchise industry for its elicited positive economic derivatives

Membrane curvature sensing by amphipathic helices:a single liposome study using a-synuclein and annexin B12

Preferential binding of proteins on curved membranes (membrane curvature sensing) is increasingly emerging as a general mechanism whereby cells may effect protein localization and trafficking. Here we use a novel single liposome fluorescence microscopy assay to examine a common sensing motif, the amphipathic helix (AH), and provide quantitative measures describing and distinguishing membrane binding and sensing behavior. By studying two AH-containing proteins, α-synuclein and annexin B12, as well as a range of AH peptide mutants, we reveal that both the hydrophobic and hydrophilic faces of the helix greatly influence binding and sensing. Although increased hydrophobic and electrostatic interactions with the membrane both lead to greater densities of bound protein, the former yields membrane curvature-sensitive binding, whereas the latter is not curvature-dependent. However, the relative contributions of both components determine the sensing of AHs. In contrast, charge density in the lipid membrane seems important primarily in attracting AHs to the membrane but does not significantly influence sensing. These observations were made possible by the ability of our assay to distinguish within our samples liposomes with and without bound protein as well as the density of bound protein. Our findings suggest that the description of membrane curvature-sensing requires consideration of several factors such as short and long range electrostatic interactions, hydrogen bonding, and the volume and structure of inserted hydrophobic residues