Three level atom optics in dipole traps and waveguides

An analogy is explored between a setup of three atomic traps coupled via tunneling and an internal atomic three-level system interacting with two laser fields. Within this scenario we describe a STIRAP like process which allows to move an atom between the ground states of two trapping potentials and analyze its robustness. This analogy is extended to other robust and coherent transport schemes and to systems of more than a single atom. Finally it is applied to manipulate external degrees of freedom of atomic wave packets propagating in waveguides.Comment: 14 pages, 6 figures; submitted to special issue 'Quantum Control of Light and Matter' of Optics Communication

The (de)politicisation of the educational problem. An ethnographic/genealogical study of school privatisation in a Chilean city

This thesis contributes to the agenda of de-neoliberalising education by developing a critique of the socio-cultural changes that the neoliberal turn has generated in Chilean society in relation to education. Framing the locus of observation at the level of a city, the research aim is to explore how school privatisation has transformed the modes in which people take part in every day and re-situated the production of the educational realm, through an analysis of how new practices and discourses gradually became the new truth at a local level. My general question regarding the effects of privatisation is who, in the city context, are allowed to problematise education, and where and how do these problematisations take place. The thesis draws upon an ethnographic/genealogical study focused on the city of Rancagua, which included twelve months of fieldwork between 2013 and 2014. The study has a double character, that is both to understand the local assemblage of discourses, practices and subjects that were shaping the school problem at this time, and to trace the historical processes that rendered this present possible, as well as intelligible. While each of the chapters concerned with ‘findings’ focus on specific subjects and urban dynamics affected by school privatisation, together they describe how education gradually ceased to be a public matter –a concern for the polis– becoming instead a de-politicised issue approached privately either as consumer or entrepreneur. On the other hand, the chapters also show that while the political dislocation of the educational question is very evident, both old and new social actors are beginning now to reclaim the right to problematise and make decisions about the daily production of education, as a social field that affects them both individually and collectively

Learner-controlled selection of tasks with different surface and structural features: Effects on transfer and efficiency

Surface task features are more salient than structural task features and thus easier to recognize for novices. It is predicted that the more salient the task features the better learners can choose personally relevant and varied tasks, which enhances learning transfer. To investigate this prediction, a 2 x 2 factorial experiment with 72 participants studied the effects of control over tasks that differ in their surface features (learner, program) and in their structural features (learner, program). Learner control over the selection of tasks with salient surface features enables learners to select personally relevant and varied tasks. This is believed to yield higher effectiveness (i.e., higher near and far transfer test performance) as well as higher efficiency (i.e. higher transfer test performance combined with lower associated mental effort). Learner control over the selection of tasks with non-salient structural features does not enable learners to select personally relevant and varied tasks and is therefore not expected to yield beneficial effects on learning. The results show positive effects of learner control over the selection of tasks with salient surface features for efficiency on the far transfer test but not for effectiveness. Theoretical and practical implications are discussed

Amorphous silica nanoparticles aggregate human platelets: potential implications for vascular homeostasis

J Jose Corbalan1,2, Carlos Medina1, Adam Jacoby2, Tadeusz Malinski2, Marek W Radomski11School of Pharmacy and Pharmaceutical Sciences, Faculty of Health Sciences, Panoz Institute, Trinity College Dublin, Ireland; 2Department of Chemistry and Biochemistry, Ohio University, Athens, OH, USABackground: Amorphous silica nanoparticles (SiNP) can be used in medical technologies and other industries leading to human exposure. However, an increased number of studies indicate that this exposure may result in cardiovascular inflammation and damage. A high ratio of nitric oxide to peroxynitrite concentrations ([NO]/[ONOO-]) is crucial for cardiovascular homeostasis and platelet hemostasis. Therefore, we studied the influence of SiNP on the platelet [NO]/[ONOO-] balance and platelet aggregation.Methods: Nanoparticle–platelet interaction was examined using transmission electron microscopy. Electrochemical nanosensors were used to measure the levels of NO and ONOO- released by platelets upon nanoparticle stimulation. Platelet aggregation was studied using light aggregometry, flow cytometry, and phase contrast microscopy.Results: Amorphous SiNP induced NO release from platelets followed by a massive stimulation of ONOO- leading to an unfavorably low [NO]/[ONOO-] ratio. In addition, SiNP induced an upregulation of selectin P expression and glycoprotein IIb/IIIa activation on the platelet surface membrane, and led to platelet aggregation via adenosine diphosphate and matrix metalloproteinase 2-dependent mechanisms. Importantly, all the effects on platelet aggregation were inversely proportional to nanoparticle size.Conclusions: The exposure of platelets to amorphous SiNP induces a critically low [NO]/[ONOO-] ratio leading to platelet aggregation. These findings provide new insights into the pharmacological profile of SiNP in platelets.Keywords: amorphous silica nanoparticles, nanotoxicology, nitric oxide, peroxynitrite, platelet aggregatio

Designing on-demand education for simultaneous development of domain-specific and self-directed learning skills

On-demand education enables individual learners to choose their learning pathways according to their own learning needs. They must use self-directed learning (SDL) skills involving self-assessment and task selection to determine appropriate pathways for learning. Learners who lack these skills must develop them because SDL skills are prerequisite to developing domain-specific skills. This article describes the design of an on-demand learning environment developed to enable novices to simultaneously develop their SDL and domain-specific skills. Learners received advice on their self-assessments and their selections of subsequent learning tasks. In the domain of system dynamics – a way to model a dynamic system and draw graphs depicting the system’s behaviour over time – advice on self-assessment is provided in a scoring rubric containing relevant performance standards. Advice on task selection indicates all relevant task aspects to be taken into account, including recommendations for suitable learning tasks which meet the individual learner’s needs. This article discusses the design of the environment and the learners’ perceptions of its usefulness. Most of the times, the learners found the advice appropriate and they followed it in 78% of their task selections

The favorable kinetics and balance of nebivolol-stimulated nitric oxide and peroxynitrite release in human endothelial cells

Background: Nebivolol is a third-generation beta-blocker used to treat hypertension. The vasodilation properties of nebivolol have been attributed to nitric oxide (NO) release. However, the kinetics and mechanism of nebivolol-stimulated bioavailable NO are not fully understood. Methods: Using amperometric NO and peroxynitrite (ONOO-) nanosensors, β3-receptor (agonist: L-755,507; antagonists: SR59230A and L-748,337), ATP efflux (the mechanosensitive ATP channel blocker, gadolinium) and P2Y-receptor (agonists: ATP and 2-MeSATP; antagonist: suramin) modulators, superoxide dismutase and a NADPH oxidase inhibitor (VAS2870), we evaluated the kinetics and balance of NO and ONOO- stimulated by nebivolol in human umbilical vein endothelial cells (HUVECs). NO and ONOO- were measured with nanosensors (diameter ~ 300 nm) placed 5 ± 2 μm from the cell membrane and ATP levels were determined with a bioluminescent method. The kinetics and balance of nebivolol-stimulated NO and ONOO- were compared with those of ATP, 2-MeSATP, and L-755,507. Results: Nebivolol stimulates endothelial NO release through β3-receptor and ATP-dependent, P2Y-receptor activation with relatively slow kinetics (75 ± 5 nM/s) as compared to the kinetics of ATP (194 ± 10 nM/s), L-755,507 (108 ± 6 nM/s), and 2-MeSATP (105 ± 5 nM/s). The balance between cytoprotective NO and cytotoxic ONOO- was expressed as the ratio of [NO]/[ONOO-] concentrations. This ratio for nebivolol was 1.80 ± 0.10 and significantly higher than that for ATP (0.80 ± 0.08), L-755,507 (1.08 ± 0.08), and 2-MeSATP (1.09 ± 0.09). Nebivolol induced ATP release in a concentration-dependent manner. Conclusion: The two major pathways (ATP efflux/P2Y receptors and β3 receptors) and several steps of nebivolol-induced NO and ONOO- stimulation are mainly responsible for the slow kinetics of NO release and low ONOO-. The net effect of this slow kinetics of NO is reflected by a favorable high ratio of [NO]/[ONOO-] which may explain the beneficial effects of nebivolol in the treatment of endothelial dysfunction, hypertension, heart failure, and angiogenesis

A novel nonsense mutation in the melanocortin-4 receptor associated with obesity in a Spanish population

BACKGROUND: In recent years, several groups have reported dominant inheritance of obesity conferred by missense, nonsense and frameshift mutations in the melanocortin 4 receptor gene (MC4R). Hence, MC4R is involved in the most common monogenic form of human obesity described so far. OBJECTIVES: In this context, we screened a Spanish population, composed of obese subjects and normal weight controls, for mutations in the MC4-R by single-strand conformational polymorphism (SSCP). SUBJECTS AND METHODS: Overall 313 individuals, 159 obese subjects (body mass index: BMI: 37.6 kg/m2, 95% CI: 36.7–38.5 kg/m2) and 154 normal weight control subjects (BMI: 22.3 kg/m2, 95% CI: 22.0–22.6 kg/m2) were screened for MC4-R mutations. RESULTS: We detected a novel nonsense mutation at codon 16 of the MC4-R in an obese female (BMI: 30.0 kg/m2) and a previously described missense mutation (Val-253-Ile) located within the sixth trans-membrane domain of the MC4-R in a normal weight individual (BMI: 19.0 kg/m2). The polymorphism Val-103-Ile was detected in one obese individual, while four subjects (two cases and two controls) with the polymorphism Ile-251-Leu were found. CONCLUSIONS: We have identified a novel nonsense mutation (Trp-16-Stop) that, based on previously described frameshift and nonsense mutations, most likely results in dominantly inherited obesity. Within this Spanish population, the frequency of the Ile-251-Leu polymorphism of the MC4R was similar in obese and control subjects (about 1.3%), while the polymorphism Val-103-Ile was only detected in an obese individual (0.6%)