Thermoelectric efficiency of topological insulators in a magnetic field

We study the thermoelectric properties of three-dimensional topological insulators in magnetic fields with many holes (or pores) in the bulk. We find that at high density of these holes in the transport direction the thermoelectric figure of merit, ZT, can be large due to the contribution of the topologically protected conducting surfaces and the suppressed phonon thermal conductivity. By applying an external magnetic field a subgap can be induced in the surface states spectrum. We show that the thermoelectric efficiency can be controlled by this tunable subgap leading to the values of ZT much greater than 1. Such high values of ZT for reasonable system parameters and its tunability by magnetic field make this system a strong candidate for applications in heat management of nanodevices, especially at low temperatures.Comment: 9 pages, 4 figures, Proceedings of MMM 201

Inflammatory Activity on Natalizumab Predicts Short-term but not Long-term Disability in Multiple Sclerosis

BACKGROUND: In people with multiple sclerosis treated with interferon-beta or glatiramer acetate, new MRI lesions and relapses during the first year of treatment predict a poor prognosis. OBJECTIVE: To study this association in those receiving natalizumab. METHODS: Data were collected on relapses, new MRI activity, and Modified Rio Score after initiation of natalizumab in an observational cohort of 161 patients with high baseline disability. These were correlated with Expanded Disability Status Scale (EDSS) progression at years 1, 2, 3, and 3-7 after treatment initiation, versus pre-treatment baseline. RESULTS: 46/161 patients had a relapse in the first year and 44/161 had EDSS progression by year 2. Relapses and Modified Rio Score in the first year of treatment predicted EDSS progression at year 1 and 2 after treatment initiation. However, this effect disappeared with longer follow-up. Paradoxically, there was a trend towards inflammatory activity on treatment (first year Modified Rio Score, relapses, and MRI activity) predicting a lower risk of EDSS progression by years 3-7, although this did not reach statistical significance. Those with and without EDSS progression did not differ in baseline age, EDSS, or pre-treatment relapse rate. Relapses in year 0-1 predicted further relapses in years 1-3. CONCLUSIONS: Breakthrough inflammatory activity after natalizumab treatment is predictive of short-term outcome measures of relapses or EDSS progression, but does not predict longer term EDSS progression, in this cohort with high baseline disability

Women’s perception of quality and utilization of antenatal care and delivery services in Oshimili South Local Government Area of Delta State, Nigeria

Background: The perception of quality of antenatal care and delivery services is one of the several factors that influence utilization of these services. This study assessed the perception of quality and utilization of antenatal care (ANC) and delivery services among women of childbearing age in Oshimili South Local Government Area (LGA) of Delta State, Nigeria.Methods: A cross-sectional study among 301 women aged 15-49 years selected by multistage random sampling technique using mixed methods of data collection. Quantitative data were analyzed using SPSS version 21 while thematic analysis was done for the qualitative data.Results: The mean age of the women was 32.0 ± 2.5 years. Most were married 287 (95.3%), had secondary education 211 (70.1%)) and self-employed 227 (75.4%). One hundred and forty-eight (49.2%) had good perception of technical competence of staff, 132 (43.9%) their safety consciousness and 134 (44.5%) effectiveness/efficiency of drugs. However, 136 (43.5%) had poor perception of waiting time, 118 (39.2%) health workers respectfulness and 116 (38.5%) compassion for patients. Two hundred and seventy-three (90.7%) and 251(83.4%) utilized ANC and delivery services, respectively, while 22 (7.3%) delivered at home.Conclusion: The women’s perception of quality of ANC and delivery services varied across domains. There was a high level of utilization of antenatal care and delivery services. However, there were few traditional birth attendant (TBA) and home deliveries. Addressing the issues of long waiting time and attitude of health workers will encourage full scale utilization of health facilities and discourage TBA and home deliveries Keywords: Antenatal care; Delivery services; Perception; Quality of care; Utilization; Nigeri

Large thermoelectric figure of merit for 3D topological Anderson insulators via line dislocation engineering

We study the thermoelectric properties of three-dimensional topological Anderson insulators with line dislocations. We show that at high densities of dislocations the thermoelectric figure of merit ZT can be dominated by one-dimensional topologically-protected conducting states channeled through the lattice screw dislocations in the topological insulator materials with a non-zero time-reversal-invariant momentum such as Bi_{1-x}Sb_x. When the chemical potential does not exceed much the mobility edge the ZT at room temperatures can reach large values, much higher than unity for reasonable parameters, hence making this system a strong candidate for applications in heat management of nano-devices.Comment: 4 pages, 3 figure

Size-fractionated photosynthesis/irradiance relationships during Phaeocystis antarctica-dominated blooms in the Ross Sea, Antarctica

In the Ross Sea, there are two major phytoplankton functional groups: diatoms and prymnesiophytes (dominated by Phaeocystis antarctica). Phaeocystis antarctica often occurs in colonial form, but also as solitary cells, and the two forms have distinct ecological roles. A comparison of the growth characteristics of solitary and colonial forms of Phaeocystis sp. is essential to understanding the differential impact each has on biogeochemical and ecological processes, and to allow parameterization of each form in numerical models. We measured the biomass and photosynthetic responses of two size fractions (\u3e 20 and \u3c 20 mu m), representing colonies and solitary cells, at locations dominated by P. antarctica to assess the relative photosynthetic potential of the two forms. While the relative contribution of each form to total P. antarctica biomass differed among years, there were no significant differences between maximum photosynthetic rates of colonial and solitary forms within years. Substantial interannual variations in biomass and maximum photosynthetic rates normalized to chlorophyll a (PmB) and initial light-limited rates of photosynthesis (alpha) were observed among years for the colonial fractions; however, interannual variations in maximum rates of photosynthesis or alpha of solitary cells were not observed. A laboratory experiment with P. antarctica, together with field data, showed that growth stage of colonies strongly affected the maximum photosynthetic rates. Under nutrient-replete conditions and exponential growth, colonial cells had higher maximum photosynthetic rates than solitary cells, but as growth rate declined and senescence began, the solitary cells\u27 rates became greater. This may be a reason for the high abundance of colonies that is often found in the Ross Sea during austral spring. Our results suggest that photosynthetic rates may influence the composition of the morphotypes of Phaeocystis, but do not appear to be the sole factor in regulating this critical biological variable

Technologies for Migration and Population Analysis: Spatial Interaction Data Applications

This initial chapter has two aims. Firstly, it seeks to clarify definitional and conceptual issues relating to the key interaction phenomena, migration and commuting, on which we concentrate in this book and for which we strive to obtain information to enhance our understanding of the processes that are taking place in the real world. The chapter explains the conceptual distinction between migrants and migrations, the importance of which becomes clear when the difference between transition and movement data is outlined, and it considers the alternative units of migrant measurement that are used such as individuals, wholly moving households and moving groups. Whilst migration tends to be measured over a period of time, typically a year, commuting is an activity that occurs on a much more frequent basis and consequently is usually measured as the numbers making a journey on one day. The chapter indicates how commuting to work and commuting to study are defined and measured. Secondly, the chapter contains the summary of an audit of interaction data sources, outlining the characteristics of the different types of data that are available from censuses, registers and surveys. Particular emphasis is placed on the former, the Census of Population, for which there are a number of data products providing migration and commuting counts at different spatial scales and disaggregated by various attributes; micro data are distinguished from macro data. However, the chapter also introduces a range of other interaction data sources such as the registers of National Health Service patients, the Pupil Level Annual School Census, the databases of the Higher Education Statistics Agency, various national level surveys such as the Labour Force Survey and the International Passenger Survey. In some cases, the data are exemplified using tables or maps. The chapter concludes with a reflection on the importance of the census as a key data source for small area analysis and a plea that, in a post-census world, sufficient steps be taken by central government to ensure the creation and provision of information systems for monitoring migration and commuting in an effective way, providing accurate and reliable intelligence on trends and creating opportunities for new research projects that develop explanations

Analyzing First-Person Stories Based on Socializing, Eating and Sedentary Patterns

First-person stories can be analyzed by means of egocentric pictures acquired throughout the whole active day with wearable cameras. This manuscript presents an egocentric dataset with more than 45,000 pictures from four people in different environments such as working or studying. All the images were manually labeled to identify three patterns of interest regarding people's lifestyle: socializing, eating and sedentary. Additionally, two different approaches are proposed to classify egocentric images into one of the 12 target categories defined to characterize these three patterns. The approaches are based on machine learning and deep learning techniques, including traditional classifiers and state-of-art convolutional neural networks. The experimental results obtained when applying these methods to the egocentric dataset demonstrated their adequacy for the problem at hand.Comment: Accepted at First International Workshop on Social Signal Processing and Beyond, 19th International Conference on Image Analysis and Processing (ICIAP), September 201