Method Development for Vitamin C Quantification in Two Complex Matrices

The following liquid chromatographic (LC) method developments and applied research studies were done using two complex food matrices, potatoes and elderberries, which are common to the state of Maine. Potatoes are Maine’s largest agricultural crop, a staple food in most U.S. households, and are, from an analytical standpoint, considered a complex matrix due to the high starch content that can be difficult to remove without degrading or removing nutrients in the process. Elderberries are an emerging crop in the U.S. because of their antioxidant and anti-viral properties and are found growing wild, throughout Maine. Elderberries are also considered a complex matrix because of the large number of compounds naturally present in the berries, including a range of flavonoids. Many flavonoids have similar chemical structures to vitamin C, which makes removing them without degradation or removing the vitamin C difficult. Both methods described in this thesis were created for use with high performance liquid chromatography and use Tris(2-carboxyethyl)phosphine Hydrochloride (TCEP) as the reducing agent. The experiments that follow the method development for these matrices center around accurate nutrient reporting and interest in nutrient variation. The potato method was applied to a research question of inter-variation in vitamin C content in a single, consume- available purchase package of potatoes. For this study eight different varieties of potatoes were purchased from a local supermarket and measured for ascorbic acid, dehydroascorbic acid, and total vitamin C concentrations. The results showed a significant variation between potatoes from the same purchase package. The variety with the largest variation in total vitamin C had concentrations ranging between 3.90 – 23.38 mg/100g. Additional research on other commercially available individual produce will allow the USDA to report nutrient ranges for foods as opposed to the single nutrient content, as are currently listed in the National Nutrient Database for Standard Reference. The applied elderberry experiment focused on whether wild elderberries grown in different locations throughout Northern and Central Maine have significant differences in vitamin C content. For this study fourteen frozen elderberry samples and seventeen freeze-dried elderberry samples were used, all collected throughout Northern and Central Maine. Samples were measured for ascorbic acid, dehydroascorbic acid, and total vitamin C. Results show significant variation in total vitamin C levels between samples grown in different locations

Detecting event-related recurrences by symbolic analysis: Applications to human language processing

Quasistationarity is ubiquitous in complex dynamical systems. In brain dynamics there is ample evidence that event-related potentials reflect such quasistationary states. In order to detect them from time series, several segmentation techniques have been proposed. In this study we elaborate a recent approach for detecting quasistationary states as recurrence domains by means of recurrence analysis and subsequent symbolisation methods. As a result, recurrence domains are obtained as partition cells that can be further aligned and unified for different realisations. We address two pertinent problems of contemporary recurrence analysis and present possible solutions for them.Comment: 24 pages, 6 figures. Draft version to appear in Proc Royal Soc

Management of peri-prosthetic fractures around total hip arthroplasty: a contemporary review of surgical options

The burden of periprosthetic fractures is increasing with increasing volumes of total hip arthroplasty. These injuries often occur in older patients with more significant co-morbidity and osteopenia. Management of these injuries is often resource intensive and can present significant socioeconomic challenges. Understanding the principles of surgical management these cases and recognising when fixation or replacement is required is critical. The aim of this article is to present a contemporary evidence-based review of the surgical fixation options for management of periprosthetic fractures in the presence of well-fixed or loose components

Quantitating the epigenetic transformation contributing to cholesterol homeostasis using Gaussian process.

To understand the impact of epigenetics on human misfolding disease, we apply Gaussian-process regression (GPR) based machine learning (ML) (GPR-ML) through variation spatial profiling (VSP). VSP generates population-based matrices describing the spatial covariance (SCV) relationships that link genetic diversity to fitness of the individual in response to histone deacetylases inhibitors (HDACi). Niemann-Pick C1 (NPC1) is a Mendelian disorder caused by >300 variants in the NPC1 gene that disrupt cholesterol homeostasis leading to the rapid onset and progression of neurodegenerative disease. We determine the sequence-to-function-to-structure relationships of the NPC1 polypeptide fold required for membrane trafficking and generation of a tunnel that mediates cholesterol flux in late endosomal/lysosomal (LE/Ly) compartments. HDACi treatment reveals unanticipated epigenomic plasticity in SCV relationships that restore NPC1 functionality. GPR-ML based matrices capture the epigenetic processes impacting information flow through central dogma, providing a framework for quantifying the effect of the environment on the healthspan of the individual

Variable length-based genetic representation to automatically evolve wrappers

The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-642-12433-4_44Proceedings 8th International Conference on Practical Applications of Agents and Multiagent SystemsThe Web has been the star service on the Internet, however the outsized information available and its decentralized nature has originated an intrinsic difficulty to locate, extract and compose information. An automatic approach is required to handle with this huge amount of data. In this paper we present a machine learning algorithm based on Genetic Algorithms which generates a set of complex wrappers, able to extract information from theWeb. The paper presents the experimental evaluation of these wrappers over a set of basic data sets.This work has been partially supported by the Spanish Ministry of Science and Innovation under the projects Castilla-La Mancha project PEII09-0266-6640, COMPUBIODIVE (TIN2007-65989), and by V-LeaF (TIN2008-02729-E/TIN)

BMQ

BMQ: Boston Medical Quarterly was published from 1950-1966 by the Boston University School of Medicine and the Massachusetts Memorial Hospitals

Solder paste reflow modeling for flip chip assembly

Solder paste printing and reflow can provide low cost techniques producing the solder bumps on flip chips. Solder paste consists of a dense suspension of solder particles in a fluid medium (vehicle) that acts as an oxide reducing agent (flux) during reflow, cleaning the metal surfaces of oxides. This paper reports on optical observations of paste behaviour at the small length scales associated with flip chip solder joints, and attempts to model the process using Computational Fluid Dynamics (CFD). Comparison of optical observations and CFD modelling show that the behaviour of the solder cannot be described simply by surface tension and viscous flow effects and it is deduced that oxides are still present on the solder surfaces during the early stages of reflow. The implications for paste heating method and solder volume are discussed, and a preliminary CFD model (based on FIDAP) incorporating the effect of the oxide layers is presented