Averaging t-structures and extension closure of aisles

We ask when a finite set of t-structures in a triangulated category can be `averaged' into one t-structure or, equivalently, when the extension closure of a finite set of aisles is again an aisle. There is a straightforward, positive answer for a finite set of compactly generated t-structures in a big triangulated category. For piecewise tame hereditary categories, we give a criterion for when averaging is possible, and an algorithm that computes truncation triangles in this case. A finite group action on a triangulated category gives a natural way of producing a finite set of t-structures out of a given one. If averaging is possible, there is an induced t-structure on the equivariant triangulated category.Comment: 26 pages, 11 figures. v2: fixed minor mistakes, improved presentation. Comments still welcome

A Max-Plus Model of Asynchronous Cellular Automata

This paper presents a new framework for asynchrony. This has its origins in our attempts to better harness the internal decision making process of cellular automata (CA). Thus, we show that a max-plus algebraic model of asynchrony arises naturally from the CA requirement that a cell receives the state of each neighbour before updating. The significant result is the existence of a bijective mapping between the asynchronous system and the synchronous system classically used to update cellular automata. Consequently, although the CA outputs look qualitatively different, when surveyed on "contours" of real time, the asynchronous CA replicates the synchronous CA. Moreover, this type of asynchrony is simple - it is characterised by the underlying network structure of the cells, and long-term behaviour is deterministic and periodic due to the linearity of max-plus algebra. The findings lead us to proffer max-plus algebra as: (i) a more accurate and efficient underlying timing mechanism for models of patterns seen in nature, and (ii) a foundation for promising extensions and applications.Comment: in Complex Systems (Complex Systems Publications Inc), Volume 23, Issue 4, 201

Effect of phytase on phytate P utilization by turkeys

An in vitro method was developed for poultry to predict inorganic phosphorus release from maize-soya bean feeds containing supplemental phytase (E.C. 3.1.3.8), and to quantify the effect of acid phosphatase (E.C. 3.1,3.2.), fungal protease (E.C. 3.4.23.6) and Aspergillus niger cellulase (E.C. 3.2.1.4.) on phytate dephosphorylation. Pepsin and pancreatin digestion periods were preceded by a 30 min preincubation at pH 5.25 to simulate digestion in the crop of poultry. Pancreatin digestion was carried out in dialysis tubings, with a ratio of about 1:25 (v/v) between the digesta and dialyzing medium, to simulate gradient absorption from the duodenum. The feed/water ratio was kept within physiological limits and a constant feed weight to digestive enzymes was maintained. There was a linear response to increasing dosages of phytase up to 1000 FTU/kg feed, and to increasing phosphate concentration in feeds. In vivo validation was performed with growing turkeys (1-3 wk) fed diets containing 12 g/kg of calcium; 0, 500, 1000 FTU/kg of phytase in a factorial arrangement with 0, 1, 2, 3 g/kg of supplemental phosphate (from KH2PO4). After a simple transformation (variable/in vitro phosphorus = f (in vitro phosphorus)) amounts of phosphorus hydrolyzed from feed samples by in vitro digestions correlated with the 3 week body weight gains (R= 0.986 P [less than] 0.0001), toe ash (R=0.952 P [less than] 0.0001), feed intake (R=0.994 P [less than] 0.0001) and feed efficiency (R=0.992 P [less than] 0.0001). The dephosphorylating ability of phytase in vitro was significantly enhanced (P [less than] 0.05) by the addition of acid phosphatase. Fungal acid protease and Aspergillus niger cellulase also enhanced the dephosphorylation process in vitro.Project # G-2029-01 Agreement # 14-08-0001-G-2029-0

A realist evaluation of NHS managers' experiences of managing staff poor performance.

Managing staff underperformance is one of the most difficult things that a manager is required to do and is often avoided. The management of staff underperformance has not previously been explored from the managers' perspective.This study examines NHS managers' experiences of managing staff underperformance using a realist methodology in order to deal with the complexity of research in a social situation and to offer explanations of the described events. Seven NHS managers that had managed staff underperformance using the Trust's 'Managing Employee Performance Policy' were interviewed using a semi structured interview format. The interviews covered 21 cases. The interviews were recorded and analysed to identify specific case studies, features and themes associated with their experiences. Further literature searches were carried out based upon these themes and the case studies and the themes discussed in relation to the literature, and realist explanatory theories proposed.The main themes were that: there was no organisational culture of performance management (which included a lack of training for managers in how to manage staff underperformance and staff not knowing how to respond to critical feedback on performance); the performance management process was time consuming, took longer than was necessary and was expensive; and more time and resources were devoted to supporting non-compliant than compliant staff. The time and financial costs of managing underperformance had not been previously described.The management of underperformance hinges on the delivery of negative feedback to staff which can trigger one of three responses; i) acceptance, ii) overt (explicit) rejection or iii) covert (hidden) rejection of the feedback; these require different management strategies to deal with them. Covert rejection of feedback has not been previouslydescribed in the literature; consequently managers fail to recognise covert rejection and do not manage it appropriately.Managing underperformance had the potential to have a large emotional impact on the manager especially when staff members rejected feedback. The emotional impact on managers from their perspectives was not described in the available literature. Avoidance of the emotional impact played a large part in managers not managing underperformance.Twenty one interacting theories were proposed relating to performance management as a change management process, staff responses to negative feedback, the staff contexts that led to these responses, manager training and credibility, the impact of managing or not managing performance on the managers and on the organisation. These theories were refined with the addition of information from secondary literature searches and two were discounted as there was a lack of corroborating evidence or it was felt that the theory could be explained by an alternative means.It is intended that this thesis may offer useful theories that inform organisational change with respect to performance management of staff, the training of managers and organisational norms and form the basis for future research

Systems biology analysis of global mRNA translational regulation in Saccharomyces cerevisiae

mRNA translation is one of the fundamental and well controlled cellular process requiring the combined function of a large number of molecular components. The three main stages of translation, initiation, elongation and termination are facilitated by more than 20 proteins known as translation factors. Translation is the final step in the flow of genetic information,and regulation at this level allows for an immediate and rapid response to changes in physiological conditions. The control exerted at the systems level of translation has not precisely been characterized. Three different techniques have been employed to quantitative the control exerted by the respective translation factors. In the first approach, employing the microscopic techniques, in vivo intra-cellular distribution of translation elongation and release factors were analysed with TCM and GFP tags. The result indicates that the factors are cytoplasmically distributed which cannot influence the overall translational control. In the second approach, the protein expression levels of the elongation and release factors were titrated progressively to explore their control effects on global translation regulation. The endogenous promoter of each translation factor was substituted by the tetO7 synthetic promoter to regulate the expression level in response to varying concentrations of doxycycline. Measurement of protein synthesis rate and the growth rate at different levels of the elongation and release factors provide insight to system-level control. The results indicate that the elongation factors eEF1A and eEF2 and the release factor eRF1 exert an unexpectedly high degree of control over translation rate. Moreover, these factors, along with elongation factor eEF3 were found to be functionally dedicated to translation, in contrast to eEF1B and eRF3, which is evidently multifunctional. In the third approach, a mathematical model has been developed to represent the control landscape of the translational machinery. This translation model is a powerful tool that will be used in the quantitative analysis of translation when two factors are made limiting at a time. The extensive study carried out on the translational regulation of Saccharomyces cerevisiae reveals an interesting observation of the involvement of each translation factors. For the first time, the quantitative measurement of the translational regulation reveals the translational regulation exerted by individual translation factors.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Partial compactification of stability manifolds by massless semistable objects

We introduce two partial compactifications of the space of Bridgeland stability conditions of a triangulated category. First we consider lax stability conditions where semistable objects are allowed to have mass zero but still have a phase. The subcategory of massless objects is thick and there is an induced classical stability on the quotient category. We study deformations of lax stability conditions. Second we consider the space arising by identifying lax stability conditions which are deformation-equivalent with fixed charge. This second space is stratified by stability spaces of Verdier quotients of the triangulated category by thick subcategories of massless objects. We illustrate our results through examples in which the Grothendieck group has rank 2. For these, our partial compactification can be explicitly described and related to the wall-and-chamber structure of the stability space

Probing Bottom-up Processing with Multistable Images

The selection of fixation targets involves a combination of top-down and bottom-up processing. The role of bottom-up processing can be enhanced by using multistable stimuli because their constantly changing appearance seems to depend predominantly on stimulusdriven factors. We used this approach to investigate whether visual processing models based on V1 need to be extended to incorporate specific computations attributed to V4. Eye movements of 8 subjects were recorded during free viewing of the Marroquin pattern in which illusory circles appear and disappear. Fixations were concentrated on features arranged in concentric rings within the pattern. Comparison with simulated fixation data demonstrated that the saliency of these features can be predicted with appropriate weighting of lateral connections in existing V1 models

Discrete triangulated categories

14 pages, 1 table, v2 minor fixes and changesWe introduce and study several homological notions which generalise the discrete derived categories of D. Vossieck. As an application, we show that Vossieck discrete algebras have this property with respect to all bounded t-structures. We give many examples of triangulated categories regarding these notions

Standardised Practice-Based Oral Health Data Collection: A Pilot Study in Different Countries

BACKGROUND: The Oral Health Observatory (OHO), launched in 2014 by FDI World Dental Federation, aims to provide a coordinated approach to international oral health data collection. A feasibility project involving 12 countries tested the implementation of the methodology and data collection tools and assessed data quality from 6 countries. METHODS: National dental associations (NDAs) recruited dentists following a standardised sampling method. Dentists and patients completed paired questionnaires (N = 7907) about patients' demographics, dental attendance, oral health-related behaviours, oral impacts, and clinical measures using a mobile app. In addition, participating dentists (n = 93) completed an evaluation survey, and NDAs completed a survey and participated in workshops to assess implementation feasibility. RESULTS: Feasibility data are presented from the 12 participating countries. In addition, the 6 countries most advanced with data collection as of July 2020 (China, Colombia, India, Italy, Japan, and Lebanon) were included in the assessment of data quality and qualitative evaluation of implementation feasibility. All NDAs in these 6 countries reported interest in collecting standardised, international data for policy and communication activities and to understand service use and needs. Eighty-two percent of dentists (n = 76) reported a patient response rate of between 80% and 100%. More than 70% (n = 71) of dentists were either satisfied or very satisfied with the patient recruitment and data collection methods. There were variations in patient oral health and behaviours across countries, such as self-reporting twice-daily brushing which ranged from 45% in India to 83% in Colombia. CONCLUSIONS: OHO provides a feasible model for collecting international standardised data in dental practices. Reducing time implications, ensuring mobile app reliability, and allowing practitioners to access patient-reported outcomes to inform practice may enhance implementation