Strong limit theorems for a simple random walk on the 2-dimensional comb

We study the path behaviour of a simple random walk on the 2-dimensional comb lattice ${\mathbb C}^2$ that is obtained from ${\mathbb Z}^2$ by removing all horizontal edges off the x-axis. In particular, we prove a strong approximation result for such a random walk which, in turn, enables us to establish strong limit theorems, like the joint Strassen type law of the iterated logarithm of its two components, as well as their marginal Hirsch type behaviour.Comment: 30 pages, 1 figur

Bone marrow recovery by morphometry during induction chemotherapy for acute lymphoblastic leukemia in children

Bone marrow architecture is grossly distorted at the diagnosis of ALL and details of the morphological changes that accompany response to Induction chemotherapy have not been reported before. While marrow aspirates are widely used to assess initial response to ALL therapy and provide some indications, we have enumerated marrow components using morphometric analysis of trephine samples with the aim of achieving a greater understanding of changes in bone marrow niches. Morphometric analyses were carried out in the bone marrow trephine samples of 44 children with ALL, using a NanoZoomer HT digital scanner. Diagnostic samples were compared to those of 32 control patients with solid tumors but without marrow involvement. Samples from patients with ALL had significantly increased fibrosis and the area occupied by bony trabeculae was lower than in controls. Cellularity was higher in ALL samples due to leukemic infiltration while the percentage of normal elements such as megakaryocytes, adipocytes, osteoblasts and osteoclasts were all significantly lower. During the course of Induction therapy, there was a decrease in the cellularity of ALL samples at day 15 of therapy with a further decrease at the end of Induction and an increase in the area occupied by adipocytes and the width of sinusoids. Reticulin fibrosis decreased throughout Induction. Megakaryocytes increased, osteoblasts and osteoclasts remained unchanged. No correlation was found between clinical presentation, early response to treatment and morphological changes. Our results provide a morphological background to further studies of bone marrow stroma in ALL

Mixed pathologies including chronic traumatic encephalopathy account for dementia in retired Association football (soccer) players

In retired professional Association football (soccer) players with a past history of repetitive head impacts, chronic traumatic encephalopathy (CTE) is a potential neurodegenerative cause of dementia and motor impairments. From 1980 to 2010, 14 retired footballers with dementia were followed up regularly until death. Their clinical data, playing career and concussion history were prospectively collected. Next-of-kin consented for six to have post-mortem brain examination. Of the 14 male participants, 13 were professional and 1 was a committed amateur. All were skilled headers of the ball and had played football for an average of 26 years. Concussion rate was limited in six cases to one episode each during their careers. All cases developed progressive cognitive impairment with an average age at onset of 63.6 years and disease duration of 10 years. Neuropathological examination revealed septal abnormalities in all six post-mortem cases, supportive of a history of chronic repetitive head impacts. Four cases had pathologically confirmed CTE; concomitant pathologies included Alzheimer’s disease (N=6), TDP-43 (N=6), cerebral amyloid angiopathy (N=5), hippocampal sclerosis (N=2), corticobasal degeneration (N=1), dementia with Lewy bodies (N=1) and vascular pathology (N=1), all would have contributed synergistically to the clinical manifestations. The pathological diagnosis of CTE was established in four individuals according to the latest consensus diagnostic criteria. This finding is probably related to their past prolonged exposure to repetitive head impacts from head-to-player collisions and heading the ball thousands of time throughout their careers. Alzheimer’s disease and TDP-43 pathologies are common concomitant findings in CTE, both of which are increasingly considered as part of the CTE pathological entity in older individuals. Association Football is the most popular sport in the world and the potential link between repetitive head impacts from playing football and CTE as indicated from our findings is of considerable public health interest. Clearly a definitive link cannot be established in this clinico-pathological series, but our findings support the need for further systematic investigation including large scale case-control studies to identify at risk groups of footballers which will justify for the implementation of protective strategies

Interprocedural Reachability for Flat Integer Programs

We study programs with integer data, procedure calls and arbitrary call graphs. We show that, whenever the guards and updates are given by octagonal relations, the reachability problem along control flow paths within some language w1* ... wd* over program statements is decidable in Nexptime. To achieve this upper bound, we combine a program transformation into the same class of programs but without procedures, with an Np-completeness result for the reachability problem of procedure-less programs. Besides the program, the expression w1* ... wd* is also mapped onto an expression of a similar form but this time over the transformed program statements. Several arguments involving context-free grammars and their generative process enable us to give tight bounds on the size of the resulting expression. The currently existing gap between Np-hard and Nexptime can be closed to Np-complete when a certain parameter of the analysis is assumed to be constant.Comment: 38 pages, 1 figur

Modelling Of The Thermal Interactions Of Underground Railways With Nearby Vertical Ground Heat Exchangers In An Urban Environment

Ground source heat pumps (GSHPs) can provide an efficient way of heating and cooling buildings due to their high operating efficiencies. The implementation of these systems in urban environments could have further benefits. In such locations ground source heat is potentially available from alternative sources such as underground railways (URs). The potential benefits for using the waste heat generated by URs with localised GSHPs are established in this thesis. This was achieved through investigations of UR-GSHP interactions. The research detailed here was mainly conducted through Finite Element (FE) numerical modelling and analysis. First a preliminary two-dimensional (2D) FE model was developed. This model was highly simplified to enable rapid analysis of the systems. The model was used to establish key parameters and phenomena for more detailed additional research. Since the operation of the URs and GSHP involves complex, transient, three-dimensional (3D) transport phenomena and extreme geometrical aspect ratios, 3D numerical models of URs and vertical ground heat exchangers (GHEs) were independently developed and validated. These individual models were then built into the same modelling environment for their combined analysis. Initial investigations with the combined 3D model showed that interactions occur between URs and localised GSHPs. In order to investigate the effect of specific parameter variations on the earlier established UR-GSHP interactions, a parametric analysis was conducted. The analysis included two sets of studies. The first group of studies considered different geometrical arrangements of the systems, and the second group investigated the effect of altered operational characteristics options on the interactions. Overall the results suggested that the performance of a GSHP can be significantly improved if the GHE array is installed near to the UR tunnel. It was shown that the improvement on the GHEs average heat extraction rate due to the heat load from the UR tunnel can be high as ~ 40%, depending on the size and shape of the GHE array and its proximity to the UR tunnel(s). It was also concluded that if the design aim is to enhance the heat extraction rates of urban GSHP systems, constructing the GHEs as close as possible to the UR tunnel would be essential. The results gathered from the parametric analysis were used to develop a formula. This formula is one of the key contributions to knowledge from this research. The formula developed allows approximating the GHEs’ heat extraction improvements due to the nearby tunnel(s) heat load(s). The formula makes use of a single variable named as interaction proximity. This variable was found to be one of the key parameters impacting on UR-GSHP interactions. At the end of the thesis, conclusions are drawn concerning the thermal interactions of URs with nearby vertical GHEs and the numerical modelling of such systems. Recommendations for further research in this field are also suggested

Modelling Of The Thermal Interactions Of Underground Railways With Nearby Vertical Ground Heat Exchangers In An Urban Environment

Ground source heat pumps (GSHPs) can provide an efficient way of heating and cooling buildings due to their high operating efficiencies. The implementation of these systems in urban environments could have further benefits. In such locations ground source heat is potentially available from alternative sources such as underground railways (URs). The potential benefits for using the waste heat generated by URs with localised GSHPs are established in this thesis. This was achieved through investigations of UR-GSHP interactions. The research detailed here was mainly conducted through Finite Element (FE) numerical modelling and analysis. First a preliminary two-dimensional (2D) FE model was developed. This model was highly simplified to enable rapid analysis of the systems. The model was used to establish key parameters and phenomena for more detailed additional research. Since the operation of the URs and GSHP involves complex, transient, three-dimensional (3D) transport phenomena and extreme geometrical aspect ratios, 3D numerical models of URs and vertical ground heat exchangers (GHEs) were independently developed and validated. These individual models were then built into the same modelling environment for their combined analysis. Initial investigations with the combined 3D model showed that interactions occur between URs and localised GSHPs. In order to investigate the effect of specific parameter variations on the earlier established UR-GSHP interactions, a parametric analysis was conducted. The analysis included two sets of studies. The first group of studies considered different geometrical arrangements of the systems, and the second group investigated the effect of altered operational characteristics options on the interactions. Overall the results suggested that the performance of a GSHP can be significantly improved if the GHE array is installed near to the UR tunnel. It was shown that the improvement on the GHEs average heat extraction rate due to the heat load from the UR tunnel can be high as ~ 40%, depending on the size and shape of the GHE array and its proximity to the UR tunnel(s). It was also concluded that if the design aim is to enhance the heat extraction rates of urban GSHP systems, constructing the GHEs as close as possible to the UR tunnel would be essential. The results gathered from the parametric analysis were used to develop a formula. This formula is one of the key contributions to knowledge from this research. The formula developed allows approximating the GHEs’ heat extraction improvements due to the nearby tunnel(s) heat load(s). The formula makes use of a single variable named as interaction proximity. This variable was found to be one of the key parameters impacting on UR-GSHP interactions. At the end of the thesis, conclusions are drawn concerning the thermal interactions of URs with nearby vertical GHEs and the numerical modelling of such systems. Recommendations for further research in this field are also suggested

Promoting grammatical development through captions and textual enhancement in multimodal input-based tasks

This study assessed the extent to which captions, textually unenhanced and enhanced, can draw learners’ attention to and promote the acquisition of a second language (L2) grammatical construction. A pretest–posttest–delayed posttest experimental design was employed. Seventy-two Korean learners of English were randomly assigned to an enhanced captions group, an unenhanced captions group, and a no captions group. Each group completed a series of treatment tasks, during which they watched news clips under their respective captioning condition. The target L2 construction was the use of the present perfect versus the past simple in reporting news. For the enhanced captions group, the present perfect and past simple forms were typographically enhanced using a different color. Eye-movement indices were obtained to examine attentional allocation during the treatment, and oral and written productive tests and a fill-in-the-blank test were used to assess participants’ gains. A series of mixed-effects models found both captioning and textual enhancement effective in drawing learners’ attention to and facilitating development in the use of the target construction. In addition, positive links were identified between attention to captions and learners’ gains

Effects of vitamin D3 derivative--calcitriol on pharmacological reactivity of aortic rings in a rodent PCOS model.

Abstract BACKGROUND: The aim of this study was to examine the effects of the hyperandrogenic state in dihydrotestosterone (DHT)-induced polycystic ovary syndrome (PCOS), the vascular responses to different vasoactive agents, and the modulatory role of vitamin D3. METHODS: APCOS model was induced by DHT application in 20 female Wistar rats. Ten of the DHT treated rats simultaneously received calcitriol treatment. After 10 weeks, myographs were used to test the reactivity of isolated thoracic aortic rings to norepinephrine and acetylcholine. Thereafter, the vascular rings were incubated with the NO-synthase blocker (nitro-L-arginine methyl ester) or the cyclooxygenase inhibitor (indomethacin) for 20 min, and the effects of norepinephrine and acetylcholine were re-evaluated. RESULTS: Norepinephrine-induced vasoconstriction was enhanced after DHT treatment, but this effect was attenuated by calcitriol administration. Vasorelaxation of DHT-treated thoracic aortic rings was impaired, but this could be partly reversed by calcitriol application. Impaired NO-dependent vasorelaxation in DHT-treated animals was mostly reversed by concomitant calcitriol administration, but this effect was diminished by prostanoid-dependent vasoconstriction. CONCLUSIONS: These studies show that the enhanced sensitivity to vasoconstrictors and impaired NO-dependent vasorelaxation in hyperandrogenic PCOS rats could be partially reversed by calcitriol treatment

Project SHOES: Secondary heat opportunities from electrical substations

Through the mechanism of stepping up and stepping down voltages with electrical power transformers, losses in the form of heat occur and are dissipated to the atmosphere. These losses have the opportunity to be recovered and upgraded to help support the thermal demands of buildings as allow carbon secondary heat source. The electrification of heat facilitates the uptake of electrically driven heat pumps that are efficient means of upgrading low temperature heat sources to commonly used temperatures and the employment of district heating networks enables the transition of these alternative heat sources into the economy. This paper describes the results discovered from an initial investigation on the contribution available from a transformer energy recovery scheme using the Southampton Bulk Supply Point substation and District Heating Scheme as a case study. Benefits to the heat sector and asset owner are analysed from the results considering the techno-economic, environmental and social performance with the aim to provide guidance to the engineering community for further in-depth feasibility studies on this waste energy recovery concep