Occupation time statistics of the random acceleration model

The random acceleration model is one of the simplest non-Markovian stochastic systems and has been widely studied in connection with applications in physics and mathematics. However, the occupation time and related properties are non-trivial and not yet completely understood. In this paper we consider the occupation time $T_+$ of the one-dimensional random acceleration model on the positive half-axis. We calculate the first two moments of $T_+$ analytically and also study the statistics of $T_+$ with Monte Carlo simulations. One goal of our work was to ascertain whether the occupation time $T_+$ and the time $T_m$ at which the maximum of the process is attained are statistically equivalent. For regular Brownian motion the distributions of $T_+$ and $T_m$ coincide and are given by L\'evy's arcsine law. We show that for randomly accelerated motion the distributions of $T_+$ and $T_m$ are quite similar but not identical. This conclusion follows from the exact results for the moments of the distributions and is also consistent with our Monte Carlo simulations.Comment: 10 pages, 4 figure

Investigating the impact of technical and vocational educational education (TVET) on youth unemployment in Ghana

Thesis submitted to the Department of Business Administration, Ashesi University College, in partial fulfillment of Bachelor of Science degree in Business Administration, April 2014Economists believe that human capital is necessary for development. This has resulted in a focus on the expansion of not just tertiary and secondary education, but also vocational education, and the use of manpower planning, as far as the Asian tigers are concerned (Taiwan, Republic of Korea, Hong Kong and Singapore) (Harris, 1996). Taking a cue from successful outcomes in Asia, this study therefore sought to find out how technical and vocational education has impacted youth unemployment in Ghana. TVET did face and continues to be plagued by persistent negative perception and other challenges even in the international context. Yet some countries, especially those in East Asia were able to grow rapidly and generate jobs especially for the youth because TVET played an important role in their development strategy. Thus, it makes sense to investigate the effect of TVET on youth unemployment in Ghana. Data was collected with Questionnaires and interviews from both current vocational school students and graduates, and a COTVET official. The research confirmed that though TVET faces a lot of challenges such as, lack of school materials, inefficient Ghanaian market, uncertified schools etc. TVET has played and still plays a significant role in creating employment for the youths especially those who come from low income families. It is imperative that the government and all other administrators of TVET understand and implement the recommendations made in this research project appropriately in order for the economy to benefit from TVET.Ashesi University Colleg

Response to “Comment on ‘Large area CMOS active pixel sensor x‐ray imager for digital breast tomosynthesis: Analysis, modeling, and characterization’ ” [Med. Phys. 43, 1578–1579 (2016)]

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135038/1/mp5041_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/135038/2/mp5041.pd

Developing Model Benchtop Systems for Microbial Experimental Evolution

Understanding how microbes impact an ecosystem has improved through advances of molecular and genetic tools, but creating complex systems that emulate natural biology goes beyond current technology. In fact, many chemical, biological, and metabolic pathways of even model organisms are still poorly characterized. Even then, standard laboratory techniques for testing microbial impact on environmental change can have many drawbacks; they are time-consuming, labor intensive, and are at risk of contamination. By having an automated process, many of these problems can be reduced or even eliminated. We are developing a benchtop system that can run for long periods of time without the need for human intervention, involve multiple environmental stressors at once, perform real-time adjustments of stressor exposure based on current state of the population, and minimize contamination risks. Our prototype device allows operators to generate an analogue of real world micro-scale ecosystems that can be used to model the effects of disruptive environmental change on microbial ecosystems. It comprises of electronics, mechatronics, and fluidics based systems to control, measure, and evaluate the before and after state of microbial cultures from exposure to environmental stressors. Currently, it uses four parallel growth chambers to perform tests on liquid cultures. To measure the population state, optical sensors (LED/photodiode) are used. Its primary selection pressure is UV-C radiation, a well-studied stressor known for its cell- and DNA-damaging effects and as a mutagen. Future work will involve improving the current growth chambers, as well as implementing additional sensors and environmental stressors into the system. Full integration of multiple culture testing will allow inter-culture comparisons. Besides the temperature and OD sensors, other types of sensors can be integrated such as conductivity, biomass, pH, and dissolved gasses such as CO and O. Additional environmental stressor systems like temperature (extreme heat or cold), metal toxicity, and other forms of radiation will increase the scale and testing range

Instrumentation for Examining Microbial Response to Changes In Environmental Pressures

The Automated Adaptive Directed Evolution Chamber (AADEC) is a device that allows operators to generate a micro-scale analog of real world systems that can be used to model the local-scale effects of climate change on microbial ecosystems. The AADEC uses an artificial environment to expose cultures of micro-organisms to environmental pressures, such as UV-C radiation, chemical toxins, and temperature. The AADEC autonomously exposes micro-organisms to selection pressures. This improves upon standard manual laboratory techniques: the process can take place over a longer period of time, involve more stressors, implement real-time adjustments based on the state of the population, and minimize the risk of contamination. We currently use UV-C radiation as the main selection pressure, UV-C is well studied both for its cell and DNA damaging effects as a type of selection pressure and for its related effectiveness as a mutagen; having these functions united makes it a good choice for a proof of concept. The AADEC roadmap includes expansion to different selection pressures, including heavy metal toxicity, temperature, and other forms of radiation.The AADEC uses closed-loop control to feedback the current state of the culture to the AADEC controller that modifies selection pressure intensity during experimentation, in this case culture density and growth rate. Culture density and growth rate are determined by measuring the optical density of the culture using 600 nm light. An array of 600 nm LEDs illuminate the culture and photodiodes are used to measure the shadow on the opposite side of the chamber.Previous experiments showed that we can produce a million fold increase to UV-C radiation over seven iterations. The most recent implements a microfluidic system that can expose cultures to multiple different selection pressures, perform non-survival based selection, and autonomously perform hundreds of exposure cycles. A scalable pump system gives the ability to pump in various different growth media to individual cultures and introduce chemical toxins during experimentation; AADEC can perform freeze and thaw cycles. We improved our baseline characterization by building a custom UV-C exposure hood, a shutter operates on a preset timer allowing the user to set exposure intensity consistently for multiple iterations

Coastal California's Fog as a Unique Habitable Niche: Design for Autonomous Sampling and Preliminary Aerobiological Characterization

Just as on the land or in the ocean, atmospheric regions may be more or less hospitable to life. The aerobiosphere, or collection of living things in Earth's atmosphere, is poorly understood due to the small number and ad hoc nature of samples studied. However, we know viable airborne microbes play important roles, such as providing cloud condensation nuclei. Knowing the distribution of such microorganisms and how their activity can alter water, carbon, and other geochemical cycles is key to developing criteria for planetary habitability, particularly for potential habitats with wet atmospheres but little stable surface water. Coastal California has regular, dense fog known to play a major transport role in the local ecosystem. In addition to the significant local (1 km) geographical variation in typical fog, previous studies have found that changes in height above surface of as little as a few meters can yield significant differences in typical concentrations, populations and residence times. No single current sampling platform (ground-based impactors, towers, balloons, aircraft) is capable of accessing all of these regions of interest.A novel passive fog and cloud water sampler, consisting of a lightweight passive impactor suspended from autonomous aerial vehicles (UAVs), is being developed to allow 4D point sampling within a single fog bank, allowing closer study of small-scale (100 m) system dynamics. Fog and cloud droplet water samples from low-altitude aircraft flights in nearby coastal waters were collected and assayed to estimate the required sample volumes, flight times, and sensitivity thresholds of the system under design.125 cloud water samples were collected from 16 flights of the Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS) instrumented Twin Otter, equipped with a sampling tube collector, occurring between 18 July and 12 August 2016 below 1 km altitude off the central coast. The collector was flushed first with 70 ethanol, then with sterile DI water, between sampling regions. Collected volumes ranged from 100 L to 12 mL. All samples were diluted serially and plated on two different types of agar, nutrient-dense (PCA) and sparse (R-2A). Plates were incubated at room temperature and counted when colonies first appeared and again at 2 weeks.Preliminary results from seven flights are consistent with generally reported colony-forming unit (CFU) values for terrestrial fog water (e.g., [4]). The PCA assay ranged from 400 to 125,000 CFU/mL, R-2A from 700 to 130,000 CFU/mL. PCA and R-2A counts were not significantly different from each other at I^ plus or minus +/- 0.05, although observationally, the R2A plates had more pigmented colonies. CFU counts from the majority of flights were not different from each other in mean at the same level of significance, but about half differed in median, indicating differences in underlying distribution. These results validate the presence of viable microorganisms in coastal California fog at levels that should be easily detectable by our sampling system. The indicated distribution differences underscore the need for small-scale, long-term sampling surveys. Future planned work includes ion chromatography for limiting nutrients, ATP quantification, and qPCR for several microbial classes of interest

Financial literacy education in Cameroon:teachers’ beliefs and perspectives

There has been a growing awareness of the importance of financial literacy in recent years, and any governments have become concerned with the levels of financial literacy of their citizens. Many have also recognized that financial literacy is especially important among the young, as this group faces increasingly more responsibility in making financial decisions. Nevertheless, there is less attention paid to financial literacy education at the primary or elementary level, especially in countries of the global south, despite the potential benefits it can offer. The main aim to explore teachers’ beliefs on financial literacy education in the primary school setting in Cameroon. Previous research on financial literacy education is mostly quantitative, focusing on students’, teachers’ or parents’ level of financial literacy and how it affects consumer behaviour. Only a few qualitative studies that look at how financial literacy can be taught effectively or how students, teachers, parents and other stakeholders perceive financial literacy education could be found, though teachers’ beliefs have been studied a lot with regards to other subjects such as mathematics, ICT and languages. Previous researches also show that teachers’ perceptions and beliefs in one-way or the other influence how they teach and/or behave towards certain subject matter such as financial literacy. My research is qualitative research and I collected from six primary school teachers who teach subjects that involve financial concepts. I used semi-structured interviews for data collection. The research questions that this study addressed were; a) what are teachers’ beliefs about financial literacy education in Cameroonian primary schools? b) To what extent do educators attempt to implement financial literacy pedagogical strategies that are also culturally relevant to the learners they work with? The results derived from the analysis indicated that primary school teachers are well aware of the importance of financial literacy education for the youths. In schools, financial literacy is taught through three broader subjects, Mathematics, Home economics and general knowledge. Teachers’ beliefs fell under procedural, epistemic and normative beliefs, and were categorized under macro, meso and micro beliefs. Most of the teachers could not practically teach financial literacy due to limited resources and training. Most of the teaching, therefore was theoretical, through problem solving exercises, family guest speakers and sometimes role play. All the same, the teachers were able to connect the lessons to the learners’ culture and immediate environment

Obtaining two polymorphic forms of paracetamol within the phase diagram with PEG 1500

International audienceStudies of the interactions between paracetamol, chosen as model active ingredient, and PEG 1500, a pharmaceutical carrier, are conducted in the solid state. Solid dispersions of PEG 1500 and paracetamol were prepared in different mass ratios. Two temperature cycles are then applied and the characterization is carried out by DSC and X-ray powder diffraction. Following this, a phase diagram is established for each cycle. On second heating, the metastable Form II of paracetamol is obtained within the PEG-based matrix. However, on the second heating, for paracetamol contents higher than 65%, Form I or form II is obtained randomly

The classical techniques for rectocele repair: Complications and outcome

Department of Digestive and Endoscopic Surgery, CHU Brugmann, Université Libre de Bruxelles, Brussels, Belgium Robrecht Van Hee Academic Surgical Center Stuivenberg, ZNA Stuivenberg, University of Antwerp, Antwerp, Belgium Christian Ngongang Department of Digestive and Endoscopic Surgery, CHU Brugmann, Université Libre de Bruxelles, Brussels, Belgium INTRODUCTION Rectocele, a rectal hernia through the rectovaginal wall into the vagina, can be an important and disabling disease, often requiring surgical treatment. Rectoceles develop due to loosening of the normally strong interstitial connective tissue between vagina and rectum, mostly as the result of repeated and strong pressure exerted on the rectovaginal septum during labor, delivery, or forceful defecation.SCOPUS: ch.binfo:eu-repo/semantics/publishe

Immune Thrombocytopenia: Recent Advances in Pathogenesis and Treatments

Immune thrombocytopenia (ITP) is a rare autoimmune disease due to both a peripheral destruction of platelets and an inappropriate bone marrow production. Although the primary triggering factors of ITP remain unknown, a loss of immune tolerance—mostly represented by a regulatory T-cell defect—allows T follicular helper cells to stimulate autoreactive splenic B cells that differentiate into antiplatelet antibody-producing plasma cells. Glycoprotein IIb/IIIa is the main target of antiplatelet antibodies leading to platelet phagocytosis by splenic macrophages, through interactions with Fc gamma receptors (FcγRs) and complement receptors. This allows macrophages to activate autoreactive T cells by their antigen-presenting functions. Moreover, the activation of the classical complement pathway participates to platelet opsonization and also to their destruction by complement-dependent cytotoxicity. Platelet destruction is also mediated by a FcγR-independent pathway, involving platelet desialylation that favors their binding to the Ashwell-Morell receptor and their clearance in the liver. Cytotoxic T cells also contribute to ITP pathogenesis by mediating cytotoxicity against megakaryocytes and peripheral platelets. The deficient megakaryopoiesis resulting from both the humoral and the cytotoxic immune responses is sustained by inappropriate levels of thrombopoietin, the major growth factor of megakaryocytes. The better understanding of ITP pathogenesis has provided important therapeutic advances. B cell-targeting therapies and thrombopoietin-receptor agonists (TPO-RAs) have been used for years. New emerging therapeutic strategies that inhibit FcγR signaling, the neonatal Fc receptor or the classical complement pathway, will deeply modify the management of ITP in the near future