Compositional nonlinear audio signal processing with Volterra series

We develop a compositional theory of nonlinear audio signal processing based on a categorification of the Volterra series. We augment the classical definition of the Volterra series to be functorial with respect to a base category whose objects are temperate distributions and whose morphisms are certain linear transformations. This leads to formulae describing how the outcomes of nonlinear transformations are affected if their input signals are first linearly processed. We then consider how nonlinear audio systems change, and introduce as a model thereof the notion of morphism of Volterra series. We show how morphisms can be parameterized and used to generate indexed families of Volterra series, which are well-suited to model nonstationary or time-varying nonlinear phenomena. We describe how Volterra series and their morphisms organize into a functor category, Volt, whose objects are Volterra series and whose morphisms are natural transformations. We exhibit the operations of sum, product, and series composition of Volterra series as monoidal products on Volt and identify, for each in turn, its corresponding universal property. We show, in particular, that the series composition of Volterra series is associative. We then bridge between our framework and a subject at the heart of audio signal processing: time-frequency analysis. Specifically, we show that an equivalence between a certain class of second-order Volterra series and the bilinear time-frequency distributions (TFDs) can be extended to one between certain higher-order Volterra series and the so-called polynomial TFDs. We end with prospects for future work, including the incorporation of nonlinear system identification techniques and the extension of our theory to the settings of compositional graph and topological audio signal processing.Comment: Master's thesi

Development of pea albumin based GNA fusion proteins as novel biopesticides for the control of aphid (Hemiptera: aphidae) crop pests.

Novel insecticidal compounds with new modes of action are urgently required as current reliance and overuse of chemical pesticides that target a limited number of sites within insect pests has driven widespread development of resistance in crop pests. Furthermore, the most widely utilised biopesticide Bacillus thuringiensis (Bt) targets lepidopteran, coleopteran and certain dipteran pests but is ineffective against hemipteran sap-sucking pests. Hemipteran sap-sucking pests cause considerable damage to crops through direct damage and transmission of many economically important plant viruses. Further, they have been documented to rapidly develop resistance to novel insecticides. Fusion of invertebrate specific neurotoxins to snowdrop lectin (Galanthus nivalis agglutinin; GNA) has previously been shown to enhance oral activity of peptide toxins by virtue of its ability to bind to the insect gut epithelium and subsequently to transport attached peptides across the gut to the circulatory system. In addition to delivering attached toxins, GNA via binding to insect gut polypeptides, was hypothesised to provide an opportunity to potentiate the efficacy of insecticidal proteins that act at the gut surface. Pea albumin (PA1b), from pea (Pisum sativum) seeds is a proteinaceous inhibitor of V-ATPase proton pumps that are localised to the insect gut epithelium. The PA1 gene cassette is expressed in planta as a preproprotein and cleaved into two mature proteins, PA1b and PA1a. PA1b has previously been shown to cause mortality when supplied in diet to several insect species from different orders including hemipteran pest species. PA1a has no documented insecticidal activity. This project focuses on the development and production of novel recombinant fusion proteins based on linking PA1b to GNA for the control of three different aphid species (pea aphid; Acrythosiphon pisum, peach potato aphid; Myzus persicae and grain aphid; Sitobion avenae). Production of a highly pure recombinant pea albumin – GNA fusion protein (PA1b/GNA) in Pichia pastoris proved challenging; multiple expression constructs with varying linker regions, orientations and histidine purification tags were typically expressed at relatively low levels and recovery from nickel affinity purification columns was poor. However, the use of a fusion protein expression construct that included a strep-tactin affinity tag allowed the recovery of relatively pure protein samples from fermented P. pastoris cultures. An LC50 ¬ of 7 nmol mL-1 PA1b/GNA against A. pisum was subsequently derived from artificial diet bioassays and this suggested that fusion of PA1b to GNA did indeed enhance toxicity as compared to activity reported for PA1b alone in the literature. However, due to low recovery rates for PA1b/GNA, an alternative approach to generate sufficient quantities of highly pure fusion proteins based upon constructs encoding both PA1b and PA1a linked to GNA (PAF/GNA) was pursued. Expression of PAF/GNA in P. pastoris resulted in higher expression levels, and more importantly, allowed the recovery of greater quantities of highly pure protein samples as compared to PA1b/GNA. The oral toxicity of PAF/GNA and recombinant PAF was assessed through artificial diet bioassays against three species of aphid pests: A. pisum (LC50 = 5 nmol mL-1), S. avenae (15 nmol mL-1) and M. persicae (34 nmol mL-1). PAF/GNA was significantly more orally toxic towards A. pisum and M. persicae as compared to recombinant PAF or GNA alone. Greater retention of PAF/GNA in the A. pisum gut over time, as compared to controls (PAF, GNA or ovalbumin) was demonstrated using confocal microscopy of A. pisum aphids pulse fed on fluorescently labelled proteins. Significant differences in toxicity were observed between A. pisum and M. persicae, it was hypothesised that this may be due to the stability of PAF/GNA when exposed to insect proteases. PAF/GNA, GNA and PAF were all similarly stable when exposed to salivary secretions from either species for up to 48 hours. Feeding assays were performed to assess the in vivo stability, no intact protein was detected in either species, but the quantity of breakdown products decreased in A. pisum over the 48 hours, possibly suggesting that the quantity of diet consumed was decreased compared to M. persicae. Antifeedant effects were indeed indicated in free choice experiments, A. pisum displayed a clear preference for diets without pea albumin or GNA, whereas M. persicae showed no significant preference except after 48 hours feeding on PAF/GNA where they preferentially fed on control diet. Whilst PAF/GNA due to its potentially limited host range is unlikely to be utilised in a commercial setting, there may be a case made for the expression of a PAF/GNA fusion protein under the control of a phloem specific promoter as a novel method to control aphids that are one of the most economically damaging groups of agricultural pests

HomeBook

Having a reliable address system is something that is often taken for granted, but simply having one comes with immense benefits. People can easily find locations of friends and family, services like taxis know exactly where to pick customers up, and emergency response units can accurately find the scene of emergencies quickly. However, in many developing countries, these are luxuries only afforded by the wealthy and privileged neighborhoods. Locations are given haphazardly through description, often leading to late arrivals. In some cases this can be a dire possibility. Our solution aims to change this by developing a mobile application that anyone can download onto their mobile device. The application uses GPS coordinates to generate a permanent address, which can then be shared with other people and services

NaGdF4:Eu3+ Nanoparticles for Enhanced X-ray Excited Optical Imaging.

X-ray luminescent nanoparticles (NPs), including lanthanide fluorides, have been evaluated for application to deep tissue in vivo molecular imaging using optical tomography. A combination of high material density, higher atomic number and efficient NIR luminescence from compatible lanthanide dopant ions indicates that particles that consist of ALnF4 (A = alkaline, Ln = lanthanide element) may offer a very attractive class of materials for high resolution, deep tissue imaging with X-ray excitation. NaGdF4:Eu3+ NPs produced an X-ray excited luminescence that was among the most efficient of nanomaterials that have been studied thus far. We have systematically studied factors such as (a) the crystal structure that changes the lattice environment of the doped Eu3+ ions within the unit cell; and extrinsic factors such as (b) a gold coating (with attendant biocompatibility) that couples to a plasmonic excitation, and (c) changes in the NPs surface properties via changes in the pH of the suspending medium-all with a significant impact on the X-ray excited luminescence of NaGdF4:Eu3+NPs. The luminescence from an optimally doped hexagonal phase NaGdF4:Eu3+ nanoparticle was 25% more intense compared to that of a cubic structure. We observed evidence of plasmonic reabsorption of midwavelength emission by a gold coating on hexagonal NaGdF4:Eu3+ NPs; fortunately, the NaGdF4:Eu3+ @Au core-shell NPs retained the efficient 5D0→7F4 NIR (692 nm) luminescence. The NaGdF4:Eu3+ NPs exhibited sensitivity to the ambient pH when excited by X-rays, an effect not seen with UV excitation. The sensitivity to the local environment can be understood in terms of the sensitivity of the excitons that are generated by the high energy X-rays (and not by UV photons) to crystal structure and to the surface state of the particles

Susceptibility of faba bean (Vicia faba L.) to heat stress during floral development and anthesis

Experiments were conducted over two years to quantify the response of faba bean (Vicia faba L.) to heat stress. Potted winter faba bean plants (cv. Wizard) were exposed to temperature treatments (18/10; 22/14; 26/18; 30/22; 34/26°C day/night) for five days during floral development and anthesis. Developmental stages of all flowers were scored prior to stress, plants were grown in exclusion from insect pollinators to prevent pollen movement between flowers, and yield was harvested at an individual pod scale, enabling effects of heat stress to be investigated at a high resolution. Susceptibility to stress differed between floral stages, flowers were most affected during initial green-bud stages. Yield and pollen germination of flowers present before stress showed threshold relationships to stress, with lethal temperatures (t50) ~28°C and ~32°C, while whole plant yield showed a linear negative relationship to stress with high plasticity in yield allocation, such that yield lost at lower nodes was partially compensated at higher nodal positions. Faba bean has many beneficial attributes for sustainable modern cropping systems but these results suggest that yield will be limited by projected climate change, necessitating the development of heat tolerant cultivars, or improved resilience by other mechanisms such as earlier flowering times

Endocrine response to small-sided games and match play in elite u19 South African soccer players

Thesis (MScSportSc)--Stellenbosch University, 2017ENGLISH ABSTRACT : Purpose Small-sided games (SSGs) are used worldwide with the intention of stimulating significant physiological adaptations in players that are specific to match demands. The external load of SSGs and matches in soccer is well documented, but far fewer studies are aimed at measuring the internal response to these activities. The endocrine response to SSGs and matches in soccer is less well known although the respective hormones; cortisol, testosterone and dehydroepiandrosterone (DHEA) provide a valid measure of training load and total stress in several other methods of exercise. This study aimed to measure the internal endocrine response to training and matches and identify any variations between playing position and whether SSGs were preparing the players for match demands. Methods 22 elite male soccer players (16 – 23 years old), divided into positional subcategories of goalkeeper (n = 4), defender (n = 7), midfielder (n = 5), and attacker (n = 6) provided saliva samples; at rest, in response to 11v11, 7v7, and 4v4 SSGs, friendly and competitive matches, and a yoyo level two intermittent endurance test (YoyoII). Cortisol, testosterone, T:C, and DHEA concentrations were analysed using an ultra-high-performance liquid chromatographic method with mass spectrometric detection in response to small-sided games and matches. Statistically, hormones were analysed through one and two way ANOVA’s to compare different time points and positions. Results Cortisol (ng/ml) increased significantly (0,70 ± 0,40 SD to 3,94 ± 3,26 SD) from resting values in response to competitive match-play immediately after the match amongst the squad as a whole (p < 0.01). Cortisol increased significantly during all small-sided games (p < 0.05). T:C ratio (ng/ml) significantly decreased (0,89 ± 1,93 to 0,19 ± 0,28) from resting values in response to competitive match-play (p < 0.01) while testosterone showed no significant changes in response to match-play. No significant differences were found between the endocrine response of all positional subgroups over any SSGs or matches. DHEA presented no significant changes between all time-points and T:C ratio remained constant throughout the eight month testing period. SSGs presented no significant differences in endocrine response based on the number of players on the field. Yoyo2 produced comparable endocrine response to those at rest amongst the squad as a whole. Conclusions SSGs do not prepare soccer players for matches because they do not stimulate the same stress response than matches. The stress response is likely correlated to more than just physical exertion, therefore cortisol could be used as an indicator of total stress including anxiety and emotional stress as opposed to physical stress alone. Different positions do not result in different internal responses to training and matches regardless of differing external positional requirements. SSGs as a method of training seems to present no risk of overtraining. Future studies should seek to correlate cortisol, testosterone and DHEA with other, more affordable measures of internal training load or be used in conjunction with external training load measures. Future studies should perform repeated testing on smaller study samples due to the high intra-individual variability of endocrine response betweentime-points.AFRIKAANSE OPSOMMING : Doel Klein-groep spele word algemeen in die wêreld gebruik met die doel om betekenisvolle fisiologiese aanpassings, wat spesifiek tot die vereistes van wedstryde is, by spelers te veroorsaak. Die eksterne lading van klein-groep spele en wedstryde in sokker is goed gedokumenteer, maar baie minder studies poog om die interne response op hierdie aktiwiteite te meet. Endokriene response op klien-groep spele en wedstryde in sokker is nog meer onbekend en tog is dit bekend dat die hormone kortisol, testosteroon en dehidorepiandrosteroon „n geldige meting vir oefenlading en totale stres van verskeie ander oefenmetodes is. Hierdie studie is uitgevoer om die interne, endokriene response op oefening en wedstryde te meet, te bepaal of hierdie ladings tussen speelposisies verskil, en of kliengroep spele die spelers voldoende voorberei vir die eise van wedstryde. Metodes 22 elite sokkerspelers (16 – 23 jaar oud), verdeel in subkategorieë volgens posisies as doelwagter (n = 4), verdediger (n = 7), middelbaanspeler (n = 5), en aanvaller (n = 5), het speekselmonsters tydens rus, in reaksie op 11v11, 7v7, en 4v4 klein-groep spele, „n vriendskaplike en kompeterende wedstryd, asook „n yoyo vlak twee uithouvermoë toets, verskaf. Kortisol-, testosteroon-, testosteroon-kortisol-ratio (T:C), en dehidorepiandrosteroonkonsentrasies (DHEA) is analiseer volgens „n ultra-hoëprestasie vloeistof chromatografiese metode met massaspektrometriese vassteling vir reaksie op klein-groep spele en wedstryde. Statistiese analises is gedoen volgens een- en twee-rigting ANOVAS om die hormone op verskillende tydpunte en tussen verskillende posisies tevergelyk. Resultate Kortisol (ng/ml) het statisties beduidend toegeneem (0,701 ± 0,401 tot 3,938 ± 3,259) vanaf rustende waardes in reaksie op kompeterende wedstryde direk na die wedstryd binne die groep as geheel (p < 0.01). Kortisol het ook statisties beduidend toegeneem in reaksie op al die klein-groep spele (p < 0.05). T:C ratio (ng/ml) het beduidend verlaag (0,891± 1,929 tot 0,193 ± 0,2800) vanaf die rustende waardes in reaksie op die kompeterende wedstryd (p < 0.01), terwyl testosteroon geen beduidende verandering getoon het in reaksie op die wedstryd nie. Geen beduidende verskille is gevind in die endokrienresponse by die verskillende posisies vir al die klein-groep spele of wedstryde nie. DHEA het geen beduidende veranderinge getoon by enige van die tydpunte nie en die T:C ratio het relatief konstant gebly oor die toetsperiode van agt maande. Klein-groep spele, gebaseer op die aantal spelers op die veld, het geen beduidende veranderinge in endokrienresponse meegebring nie. Die Yoyo2 het endokrienresponse meegebring wat vergelykbaar is met die metings van die hele groep tydens rus. Gevolgtrekking Klein-groep spele is moontlik nie die beste manier om sokkerspelers vir wedstryde voor te berei nie, aangesien dit nie dieselfde stresresponse veroorsaak as wedstryde nie. Stresresponse is waarskynlik verwant aan meer as net fisieke inspanning en kortisol kan gebruik word as aanduiding van totale stres, wat angs en emosionele stress insluit, in teenstelling met net fisieke stress. Verskillende speelposisies lei nie noodwendig tot verskillende interne response op oefening en wedstryde nie, ten spyte van die verskillende posisionele eise. Klein-groep spele as oefenmetode hou waarskynlik nie „n risiko vir ooroefening in nie. Toekomstige studies kan kortisol, testosteroon en DHEA met ander meer bekostigbare metodes vir die meet van interne lading vergelyk, of kan gebruik word saam met metings van eksterne ladings. Bykomend, kan toekomstige studies „n kleiner groep deelnemers gebruik, maar meer herhaaldelike metings doen as gevolg van die hoë intraindividuele variasie in endokrienresponse by verskeie tydpunte

The Impact of Different Incentive Policies on Hybrid Electric Vehicle Demand and Price: An International Comparison

Significant efforts to incentivize the uptake of energy efficient vehicles (EEVs) are evident across the globe. Given EEV markets are dynamic, and consumer demand may fluctuate in response to incentives, this may also lead to other market forces influencing prices. An analysis of EEV incentives, therefore, must account for the possible endogeneity between demand and pricing. Here we estimate the effects of different types of incentives on the demand and price premiums of a specific group of EEVs: plug-in and conventional hybrid electric vehicles (HEVs). For the first time we dis-entangle the endogeneity between HEV demand and price, using error components three-stage least squares (EC3SLS) regression, and establish that increased HEV price premiums lead to reduced demand. In turn, we also establish that increased HEV demand leads to lower price premiums. Additionally, we find that one-off subsidies are associated with higher consumer demand, however, unlike other types of incentives, are also associated with higher HEV price premiums. This finding suggests that HEV manufacturers and/or dealers are absorbing a significant monetary benefit from one-off subsidies, raising a question regarding the appropriateness of HEV subsidies, particularly in non-HEV manufacturing nations. We also find that higher fuel prices are associated with higher HEV demand and price premiums. Document type: Articl

Transitions - note 10

Note complète ; Résumé ; Capsule: Ingénieure ou infirmier: les choix traditionnels et non traditionnels des filles et des garçons