Linear State Models for Volatility Estimation and Prediction

This report covers the important topic of stochastic volatility modelling with an emphasis on linear state models. The approach taken focuses on comparing models based on their ability to fit the data and their forecasting performance. To this end several parsimonious stochastic volatility models are estimated using realised volatility, a volatility proxy from high frequency stock price data. The results indicate that a hidden state space model performs the best among the realised volatility-based models under consideration. For the state space model different sampling intervals are compared based on in-sample prediction performance. The comparisons are partly based on the multi-period prediction results that are derived in this report

CRISPR/CAS9-Mediated Gene Editing in Herda Equine

HERDA (Heritable Equine Regional Dermal Asthenia) is a genetic skin disease mainly found in Quarter Horses, but also in Appaloosa and American Paint breeds. HERDA is similar to Ehlers-Danlos syndrome in humans, with symptoms including stretchy skin, hyperflexible joints, and, unique to HERDA equine, spontaneous skin sloughing. Horses affected by HERDA are not suitable for performing and are oftentimes euthanized. Some carriers for the HERDA-mutation are very competitive in the American Quarter Horse industry, especially in cutting events where it is believed, yet unproven, to give them an advantage with increased flexibility. It is also possible that the genomic locus (or loci) that links to the competitive performance traits is located close to the HERDA-causing mutation, which could lead to the co-segregation of this performance trait with the HERDA-causing mutation. Direct-line breeding strategies in the last 30 years have increased the number of HERDA-affected equine causing this disease to increase in frequency among the Quarter Horse breed. Since no treatment exists for HERDA, owners often heavily invest in HERDA horses before the symptoms arise at around two years of age. These horses are often euthanized to alleviate pain and stress on the horse and to mitigate the costly upkeep by the owner. HERDA-affected horses carry a homozygous single nucleotide mutation (c.115 G\u3eA) in exon 1 of peptidyl-prolyl Isomerase B (PPIB). Gene editing approaches would be preferable for correcting this genetic disease, since it can precisely correct the mutation without altering any other genetic traits in the elite horse breeds that have been heavily selected for. By employing the CRISPR/Cas9 system, we have sought to correct the HERDA-causing mutation in the PPIB gene. The CRISPR/Cas9 system is comprised of a bacterial endonuclease protein called Cas9 and a guide RNA sequence to direct Cas9 to target the genome in a sequence-specific manner by introducing DNA double-strand breaks (DSBs). The introduction of DNA DSBs promotes the activation and recruitment of homologous recombination (HR)-mediated DNA repair machineries to repair the broken DNA; if oligonucleotides with the desired DNA sequence are co-delivered with the CRISPR/Cas9 system into cells, the HR-mediated DNA repair mechanism can replace the targeted sequence in the genome with the oligonucleotide’s sequence, therefore, achieving gene correction or editing. We designed sgRNAs to target genomic sequences in close vicinity of the HERDA-causing mutation and a single-stranded DNA oligonucleotide containing the normal (wild type) PPIB genotype. Co-delivery of the CRISPR/Cas9/sgRNA complex with the donor oligonucleotide has successfully led to the production of gene edited cells. We established single-cell derived colonies from the edited cells and achieved 7.3% monoallelicand 2.4% biallelic editing frequencies. The gene edited fibroblasts were cryopreserved as an initial step for future HERDA-free equine cloning projects to develop the first gene edited horses

Muons in extensive air showers of size 10(^4) to 10(^7) particles

Using the Durham spectrograph and Small Extensive Air Shower Array situated 40 m. above sea level, the rate of single muons and muonpairs of momentum in the range 20 GeV/c to 1000 GeV/c in air showers of size 10(^4) to 10(^7) particles have been measured. The rate of unassociated muon pairs has also been recorded. The large solid iron spectrograph (MARS) is of toroidal design having two distinct halves, which both have a maximum detectable momentum2of about 3000 GeV/c, and an acceptance of 487 cm(^2)sr for single air shower accompanied muons. Both halves are triggered by scintillation counters, whilst muon track location is achieved by digitised neon flash tubes on the Eastern half, and by photography of the flash tubes on the Westernhalf. The air shower array (SARA) has 14 plastic scintillation counters having areas varying from 0.26 m(^2) . to 2.0 m(^2). and placed in an hexagonal geometry around the spectrograph. The array has a characteristic radius of 60 m. and is sensitive to showers of size 10(^5) to 3 10(^6) particles. The measured rates of single and double muons accompanied by air showers are compared to the predictions of semi-empirical electron and muon structure functions. Broad support is found for the structure of muons for small radial distances ≤ 100 m.) as predicted by the expression introduced by Greisen (l960) including an extrapolation to muons of momentum above 1000 GeV/c. A comparison is also made with the predictions of both the CKP, and Feynman scaling model of high energy particle interactions as applied to extensive air showers by Goned (1975) and Fishbane, et al.,(l974). Evidence is found to support the suggestion (Gaisser and Maurer (1972) Fishbane, et al.,(1974),Wdowczyk and Wolfendale (1973)) that the combination of a scaling particle interaction model and an assumed primary spectrum dominated by protons predicts too low a ratio of muons to electrons in air showers at sea level. In contrast the predictions of the CKP model largely coincide with the experimental data. Some evidence is also found for coincident muon pairs at sea level unaccompanied by shower particles

An exploratory study of public opinions on the use of hydrogen energy in Wales

The introduction of hydrogen into the energy market is being pursued by governments around the world in an effort to abate climate change, provide security of supply and reduce air pollution. While technological aspects are well researched, the social aspects of the transition are not. The public's attitude and perception of hydrogen energy will be of great importance as we move closer to the implementation of the technologies. Using two focus groups this exploratory study aims to identify Welsh public opinions on the production and end use of hydrogen energy. Gender differences were apparent, as women were generally more accepting of hydrogen technology. The main concerns were safety (both of use and in production) and cost. Cost remained paramount, even in the light of environmental considerations. The groups' attitude to the development of hydrogen technology was supportive but with the caveat that price and safety should not be compromised

Brief 2: Understanding the food system: Why it matters for food policy

There is more evidence than ever before that the food system is intimately connected to major contemporary global challenges, from malnutrition to climate change. This Brief looks at what the food system is, how it is defined and the implications of that definition for a fresh approach to food policy

Computer-assisted polyp matching between optical colonoscopy and CT colonography: a phantom study

Potentially precancerous polyps detected with CT colonography (CTC) need to be removed subsequently, using an optical colonoscope (OC). Due to large colonic deformations induced by the colonoscope, even very experienced colonoscopists find it difficult to pinpoint the exact location of the colonoscope tip in relation to polyps reported on CTC. This can cause unduly prolonged OC examinations that are stressful for the patient, colonoscopist and supporting staff. We developed a method, based on monocular 3D reconstruction from OC images, that automatically matches polyps observed in OC with polyps reported on prior CTC. A matching cost is computed, using rigid point-based registration between surface point clouds extracted from both modalities. A 3D printed and painted phantom of a 25 cm long transverse colon segment was used to validate the method on two medium sized polyps. Results indicate that the matching cost is smaller at the correct corresponding polyp between OC and CTC: the value is 3.9 times higher at the incorrect polyp, comparing the correct match between polyps to the incorrect match. Furthermore, we evaluate the matching of the reconstructed polyp from OC with other colonic endoluminal surface structures such as haustral folds and show that there is a minimum at the correct polyp from CTC. Automated matching between polyps observed at OC and prior CTC would facilitate the biopsy or removal of true-positive pathology or exclusion of false-positive CTC findings, and would reduce colonoscopy false-negative (missed) polyps. Ultimately, such a method might reduce healthcare costs, patient inconvenience and discomfort.Comment: This paper was presented at the SPIE Medical Imaging 2014 conferenc

Communications platform payload definition study, executive summary

Large geostationary communications platforms have been investigated in a number of studies since 1974 as a possible means to more effectively utilize the geostationary orbital arc and electromagnetic spectrum and to reduce overall satellite communications system costs. This NASA Lewis sponsored study addresses the commercial feasibility of various communications platform payload concepts circa 1998. It defines promising payload concepts, estimates recurring costs and identifies critical technologies needed to permit eventual commercialization. Ten communications service aggregation scenarios describing potential groupings of services were developed for a range of conditions. Payload concepts were defined for four of these scenarios: (1) Land Mobile Satellite Service (LMSS), meet 100% of CONUS plus Canada demand with a single platform; (2) Fixed Satellite Service (FSS) (Trunking + Customer Premises Service (CPS), meet 20% of CONUS demands; (3) FSS (Trunking + video distribution), 10 to 13% of CONUS demand; and (4) FSS (20% of demand) + Inter Satellite Links (ISL) + TDRSS/TDAS Data Distribution