Optimal periodic dividend strategies for spectrally positive L\'evy risk processes with fixed transaction costs

We consider the general class of spectrally positive L\'evy risk processes, which are appropriate for businesses with continuous expenses and lump sum gains whose timing and sizes are stochastic. Motivated by the fact that dividends cannot be paid at any time in real life, we study $\textit{periodic}$ dividend strategies whereby dividend decisions are made according to a separate arrival process. In this paper, we investigate the impact of fixed transaction costs on the optimal periodic dividend strategy, and show that a periodic $(b_u,b_l)$ strategy is optimal when decision times arrive according to an independent Poisson process. Such a strategy leads to lump sum dividends that bring the surplus back to $b_l$ as long as it is no less than $b_u$ at a dividend decision time. The expected present value of dividends (net of transaction costs) is provided explicitly with the help of scale functions. Results are illustrated.Comment: Accepted for publication in Insurance: Mathematics and Economic

The Ageing, Longevity and Crowding Out Effects on Private and Public Savings: Evidence from Dynamic Panel Analysis

Life-cycle theory predicts ageing exerting long-term macroeconomic impacts through the reduction of private savings. Ageing can be brought either through a fall in fertility rates or a rise in longevity. However, empirical research studying macroeconomic determinants of savings generally regard age dependency as the measure capturing the process of ageing, overlooking longevity exerting an opposite impact on private savings. Since longevity and dependency are correlated determinants of private savings, omitting either potentially causes omitted variable bias. This paper considers the joint effects age dependency and longevity have on savings. In contrast to the wider literature, not only private, but also public, savings was studied. Applying dynamic panel modelling techniques to a dataset of 55 countries from 1972-2004, age dependency is found to still exert a negative effect on private savings. However, it is found that some of these reductions can potentially be offset by increased longevity. The study also reveals some level of crowding out of private sector savings associated with changes in public sector savings and find that the Ricardian Equivalence Hypothesis cannot be entirely dismissed.

M5-branes on S^2 x M_4: Nahm's Equations and 4d Topological Sigma-models

We study the 6d N=(0,2) superconformal field theory, which describes multiple M5-branes, on the product space S^2 x M_4, and suggest a correspondence between a 2d N=(0,2) half-twisted gauge theory on S^2 and a topological sigma-model on the four-manifold M_4. To set up this correspondence, we determine in this paper the dimensional reduction of the 6d N=(0,2) theory on a two-sphere and derive that the four-dimensional theory is a sigma-model into the moduli space of solutions to Nahm's equations, or equivalently the moduli space of k-centered SU(2) monopoles, where k is the number of M5-branes. We proceed in three steps: we reduce the 6d abelian theory to a 5d Super-Yang-Mills theory on I x M_4, with I an interval, then non-abelianize the 5d theory and finally reduce this to 4d. In the special case, when M_4 is a Hyper-Kahler manifold, we show that the dimensional reduction gives rise to a topological sigma-model based on tri-holomorphic maps. Deriving the theory on a general M_4 requires knowledge of the metric of the target space. For k=2 the target space is the Atiyah-Hitchin manifold and we twist the theory to obtain a topological sigma-model, which has both scalar fields and self-dual two-forms.Comment: 78 pages, 2 figure

Should Aid Reward Performance? Evidence from a Field Experiment on Health and Education in Indonesia

This paper reports an experiment in over 3,000 Indonesian villages designed to test the role of performance incentives in improving the efficacy of aid programs. Villages in a randomly-chosen one-third of subdistricts received a block grant to improve 12 maternal and child health and education indicators, with the size of the subsequent year’s block grant depending on performance relative to other villages in the subdistrict. Villages in remaining subdistricts were randomly assigned to either an otherwise identical block grant program with no financial link to performance, or to a pure control group. We find that the incentivized villages performed better on health than the non-incentivized villages, particularly in less developed areas, but found no impact of incentives on education. We find no evidence of negative spillovers from the incentives to untargeted outcomes, and no evidence that villagers manipulated scores. The relative performance design was crucial in ensuring that incentives did not result in a net transfer of funds toward richer areas. Incentives led to what appear to be more efficient spending of block grants, and led to an increase in labor from health providers, who are partially paid fee-for-service, but not teachers. On net, between 50-75% of the total impact of the block grant program on health indicators can be attributed to the performance incentives.

Novel star-shaped polymeric architectures by copper (I) mediated living radical polymerisation

This thesis has investigated the use of copper (I) mediated living radical polymerisation to form well-defined star-shaped polymers with a β-cyclodextrin core using the core- first approach. Multifunctional initiators based on β-cyclodextrin were synthesised using appropriate protection and deprotection chemistry to precisely pre-determine the functionality. By the careful chemical modification of β-cyclodextrin, multifunctional initiators with precisely 21,14 and seven initiating sites could be synthesised. Suitable reaction conditions to provide well-defined star-shaped methyl methacrylate and styrene using copper (I) mediated living radical polymerisation were determined for the multifunctional initiators. The extent of termination reactions by star-star coupling was minimised by using a low concentration of initiating species and employing relatively low reaction temperatures. The molecular weights of the star-shaped polymers were assessed using size exclusion chromatography and light scattering techniques. The linear polymeric arms could be independently assessed by cleaving them from the β-cyclodextrin core and analysing them using size exclusion chromatography. Highly-ordered porous membrane structures are formed from star-shaped poly(styrene) polymers under certain humid conditions. The optimum conditions for the formation of these honeycomb structures have been investigated and the factors that affect the pore- size have been determined. Functionalisation of the pores were also investigated

Socioeconomic determinants of multimorbidity: a population-based household survey of Hong Kong Chinese

<b>Introduction</b> Multimorbidity has been well researched in terms of consequences and healthcare implications. Nevertheless, its risk factors and determinants, especially in the Asian context, remain understudied. We tested the hypothesis of a negative relationship between socioeconomic status and multimorbidity, with contextually different patterns from those observed in the West.<p></p> <b>Methods</b> We conducted our study in the general Hong Kong (HK) population. Data on current health conditions, health behaviours, socio-demographic and socioeconomic characteristics was obtained from HK Government’s Thematic Household Survey. 25,780 individuals aged 15 or above were sampled. Binary logistic and negative binomial regression analyses were conducted to identify risk factors for presence of multimorbidity and number of chronic conditions, respectively. Sub-analysis of possible mediation effect through financial burden borne by private housing residents on multimorbidity was also conducted.<p></p> <b>Results</b> Unadjusted and adjusted models showed that being female, being 25 years or above, having an education level of primary schooling or below, having less than HK$15,000 monthly household income, being jobless or retired, and being past daily smoker were significant risk factors for the presence of multimorbidity and increased number of chronic diseases. Living in private housing was significantly associated with higher chance of multimorbidity and increased number of chronic diseases only after adjustments.<p></p> <b>Conclusions</b>Less advantaged people tend to have higher risks of multimorbidity and utilize healthcare from the public sector with poorer primary healthcare experience. Moreover, middle-class people who are not eligible for government subsidized public housing may be of higher risk of multimorbidity due to psychosocial stress from paying for the severely unaffordable private housing

Suppressing Electrical Transients Using Smart Control of the Impedance to Ground

When a device is connected to another using a cable-and-connector, e.g., a USB cable, an electrical transient can occur that can cause damage to the device or put it in an unknown state. This disclosure describes techniques to protect devices from such transient electrical spikes. The ground of the connector is coupled to the ground of the device via one of two paths, a high-impedance path or a low-impedance path. The connector-ground to device-ground coupling is mediated by a software-controlled switch, which defaults to the high-impedance path. When a cable is connected to the device, energy transfer between the connectors occurs via the high-impedance path, thereby forestalling device damage or errors. A short while after the connectors are plugged, the switch switches to the low-impedance path, which puts the device in a normally operative state

The association of types of training and practice settings with doctors’ empathy and patient enablement among patients with chronic illness in Hong Kong

Background: The increase in non-communicable disease (NCD) is becoming a global health problem and there is an increasing need for primary care doctors to look after these patients although whether family doctors are adequately trained and prepared is unknown. Objective: This study aimed to determine if doctors with family medicine (FM) training are associated with enhanced empathy in consultation and enablement for patients with chronic illness as compared to doctors with internal medicine training or without any postgraduate training in different clinic settings. Methods: This was a cross-sectional questionnaire survey using the validated Chinese version of the Consultation and Relational Empathy (CARE) Measure as well as Patient Enablement Instrument (PEI) for evaluation of quality and outcome of care. 14 doctors from hospital specialist clinics (7 with family medicine training, and 7 with internal medicine training) and 13 doctors from primary care clinics (7 with family medicine training, and 6 without specialist training) were recruited. In total, they consulted 823 patients with chronic illness. The CARE Measure and PEI scores were compared amongst doctors in these clinics with different training background: family medicine training, internal medicine training and those without specialist training. Generalized estimation equation (GEE) was used to account for cluster effects of patients nested with doctors. <b>Results</b> Within similar clinic settings, FM trained doctors had higher CARE score than doctors with no FM training. In hospital clinics, the difference of the mean CARE score for doctors who had family medicine training (39.2, SD = 7.04) and internal medicine training (35.5, SD = 8.92) was statistically significant after adjusting for consultation time and gender of the patient. In the community care clinics, the mean CARE score for doctors with family medicine training and those without specialist training were 32.1 (SD = 7.95) and 29.2 (SD = 7.43) respectively, but the difference was not found to be significant. For PEI, patients receiving care from doctors in the hospital clinics scored significantly higher than those in the community clinics, but there was no significant difference in PEI between patients receiving care from doctors with different training backgrounds within similar clinic setting. Conclusion: Family medicine training was associated with higher patient perceived empathy for chronic illness patients in the hospital clinics. Patient enablement appeared to be associated with clinic settings but not doctors’ training background. Training in family medicine and a clinic environment that enables more patient doctor time might help in enhancing doctors’ empathy and enablement for chronic illness patients