Ignition and Front Propagation in Polymer Electrolyte Membrane Fuel Cells

Water produced in a Polymer Electrolyte Membrane (PEM) fuel cell enhances membrane proton conductivity; this positive feedback loop can lead to current ignition. Using a segmented anode fuel cell we study the effect of gas phase convection and membrane diffusion of water on the spatiotemporal nonlinear dynamics - localized ignition and front propagation - in the cell. Co-current gas flow causes ignition at the cell outlet, and membrane diffusion causes the front to slowly propagate to the inlet; counter-current flow causes ignition in the interior of the cell, with the fronts subsequently spreading towards both inlets. These instabilities critically affect fuel cell performance

Biomass Fuel Use and Cardiac Function in Nepali Women.

BackgroundExposure to household air pollution (HAP) from cooking with biomass fuel affects billions of people. We hypothesized that HAP from woodsmoke, compared to other household fuels, was associated with adverse cardiovascular outcomes, of which there have been few studies.MethodsA cross-sectional study was completed in 299 females aged 40-70 years in Kaski District, Nepal, during 2017-18. All participants underwent a standard 12-lead ECG, ankle and brachial systolic blood pressure measurement, and 2D color and Doppler echocardiography. Current stove type was confirmed by inspection. Blood pressure, height, and weight were measured using a standardized protocol. Hypertension was defined as ≥140/90 mmHg or prior diagnosis. Hemoglobin A1c (HbA1c) was obtained, with diabetes mellitus defined as a prior diagnosis or HbA1C ≥ 6.5%. We used adjusted linear and logistic multivariable regressions to examine the relationship of stove type with cardiac structure and function.ResultsThe majority of women primarily used liquified petroleum gas (LPG) stoves (65%), while 12% used biogas, and 23% used wood-burning cook-stoves. Prevalence of major cardiovascular risk factors was 35% with hypertension, 19% with diabetes mellitus, and 15% current smokers. After adjustment, compared to LPG, wood stove use was associated with increased indexed left atrial volume (β = 3.15, 95% CI 1.22 to 5.09) and increased indexed left ventricular end diastolic volume (β = 7.97, 95% CI 3.11 to 12.83). There was no association between stove type and systemic hypertension, left ventricular mass, systolic dysfunction, diastolic dysfunction, pulmonary hypertension, abnormal ankle-brachial index, or clinically significant ECG abnormalities.ConclusionBiomass fuel use was associated with increased indexed left atrial volume and increased indexed left ventricular diastolic volume in Nepali women, suggesting subclinical adverse cardiac remodeling from HAP in this cross-sectional study. We did not find evidence of an association with hypertension or typical cardiac sequelae of hypertension. Future studies to confirm these results are needed

Neutrino electron scattering and left-right symmetry: future tests

Low-energy high-resolution neutrino-electron scattering experiments may play an important role in testing the gauge structure of the electroweak interaction. We propose the use of radioactive neutrino sources (e.g. $^{51}$Cr) in underground experiments such as BOREXINO and HELLAZ as a probe of the weak neutral current structure. As an illustration, we display the sensitivity of these detectors in testing the possible existence of right-handed weak neutral currents.Comment: 4 pages. Latex. 1 figure. Contributed paper, WIN97, Capri, Italy, June 199

The Borexino Thermal Monitoring & Management System and simulations of the fluid-dynamics of the Borexino detector under asymmetrical, changing boundary conditions

A comprehensive monitoring system for the thermal environment inside the Borexino neutrino detector was developed and installed in order to reduce uncertainties in determining temperatures throughout the detector. A complementary thermal management system limits undesirable thermal couplings between the environment and Borexino's active sections. This strategy is bringing improved radioactive background conditions to the region of interest for the physics signal thanks to reduced fluid mixing induced in the liquid scintillator. Although fluid-dynamical equilibrium has not yet been fully reached, and thermal fine-tuning is possible, the system has proven extremely effective at stabilizing the detector's thermal conditions while offering precise insights into its mechanisms of internal thermal transport. Furthermore, a Computational Fluid-Dynamics analysis has been performed, based on the empirical measurements provided by the thermal monitoring system, and providing information into present and future thermal trends. A two-dimensional modeling approach was implemented in order to achieve a proper understanding of the thermal and fluid-dynamics in Borexino. It was optimized for different regions and periods of interest, focusing on the most critical effects that were identified as influencing background concentrations. Literature experimental case studies were reproduced to benchmark the method and settings, and a Borexino-specific benchmark was implemented in order to validate the modeling approach for thermal transport. Finally, fully-convective models were applied to understand general and specific fluid motions impacting the detector's Active Volume.Comment: arXiv admin note: substantial text overlap with arXiv:1705.09078, arXiv:1705.0965

Self-determination of peoples in the context of supranational governance

Globalisation has proven to be a strong transformative force in almost all sectors of public life and has also left its mark on international law. The increasing number of supranational organisations being established and their increasing significance as actors that shape international and regional law is proof of this phenomenon. At the same time, self-determination of peoples remains contentious and has in recent history led to new questions emerging in a supranational setting. Catalan independence aspirations within Spain in the European Union (EU), and continued efforts to enable a second Scottish referendum on independence in post-Brexit times show the continued salience of self-determination even in mature democracies. What both cases have in common, is that both regions aspire to either remain in or re-join a supranational organisation, namely the EU. Against this background the lack of research dedicated to reassessing self-determination of peoples as international legal norm in a supranational context is striking. This thesis seeks to address that lacuna, by charting a new trajectory of the principle of self-determination of peoples in relation to supranationalism. It does so by focussing on developments in two regional frameworks: the EU and the African Union (AU). Textual interpretation following the model of Arts. 31 to 33 of the Vienna Convention on the Law of Treaties of 1969 will be the main tool of this research, with special attention paid to historical and contemporary political considerations that may have influenced the interpretation and application of the right to self-determination in different contexts. The discussion on the evolution of the norm itself is of particular interest, as is UN involvement in generating customary international law and state practice, the work on decolonisation, and the interface between self-determination and other concepts (among others human rights, indigenous peoples’ rights and development). This thesis aims to add to existing literature by bringing the results gained from looking at the above-mentioned elements together, to (re-) evaluate the interpretation of self-determination in international human rights law. Special consideration was also given to how the concepts of ‘nation’ and ‘state’ affect the interpretation of the right to self-determination in international law

Transient analysis of proton electrolyte membrane fuel cells (PEMFC) at start-up and failure

A two-dimensional, transient, single-phase computational model, incorporating water transport in the membrane and the flow and transport of species in porous gas diffusion electrodes is developed to evaluate the transient performance of a PEMFC with interdigitated gas distributors. The co-flow and counter-flow of the anode and cathode reactants are discussed to address their effects on PEMFC performance and transients. The important role of water transport in the membrane on the transients is demonstrated. The membrane’s water intake or outtake determines the duration of the transients. The effect of the operating conditions on steady state and transient performances is outlined. Overshoots and undershoots are observed in the average current density, due to a step change in the cell voltage and the cathode pressure under start-up conditions. Simulation results are used to address the role of auxiliary components in the failure modes of the PEMFC

Vizhinjam Marine Aquarium Haven for Marine Ornamentals

There has been a huge growth of public aquaria since the opening of the first public aquarium display in the Fish House at the London Zoo in t 826, and particularly in the past 20 years (Hall and Douglas 2003)

Breeding and larval rearing of three species of damselfishes (family: Pomacentridae)

The annual world ornamental fish trade is to the tune of around 4.5 billion dollars (1995) with a growth rate of about 8%. Nearly 50% of the revenue from the trade is contributed by marine ornamental fishes. With the spread of scientific knowledge on marine aquarium management and development of an array of aquarium gadgets, there is an Increased demand for tropical marine aquarium fishes in recent years and this opens up the possibility of developing a lucrative marine ornamental fish trade the worldover

The Nylon Scintillator Containment Vessels for the Borexino Solar Neutrino Experiment

Borexino is a solar neutrino experiment designed to observe the 0.86 MeV Be-7 neutrinos emitted in the pp cycle of the sun. Neutrinos will be detected by their elastic scattering on electrons in 100 tons of liquid scintillator. The neutrino event rate in the scintillator is expected to be low (~0.35 events per day per ton), and the signals will be at energies below 1.5 MeV, where background from natural radioactivity is prominent. Scintillation light produced by the recoil electrons is observed by an array of 2240 photomultiplier tubes. Because of the intrinsic radioactive contaminants in these PMTs, the liquid scintillator is shielded from them by a thick barrier of buffer fluid. A spherical vessel made of thin nylon film contains the scintillator, separating it from the surrounding buffer. The buffer region itself is divided into two concentric shells by a second nylon vessel in order to prevent inward diffusion of radon atoms. The radioactive background requirements for Borexino are challenging to meet, especially for the scintillator and these nylon vessels. Besides meeting requirements for low radioactivity, the nylon vessels must also satisfy requirements for mechanical, optical, and chemical properties. The present paper describes the research and development, construction, and installation of the nylon vessels for the Borexino experiment

The strong state and embedded dissonance: History education and populist politics in Hungary

The hopefulness that accompanied the establishment of the Republic of Hungary in 1989 was soon tempered by divided politics that seemed unable to address systemic economic woes facing the nation. Though the 1956 Revolution remains foundational, parts of the polity remain uneasy with the concept of the liberal state and instead hearken back to the Christian National politics of the interwar years to legitimize a vision of the Hungarian nation not dependent on institutions such as the International Monetary Fund (IMF), let alone the European Union (EU) which Hungary joined in 2004. The promise of economic prosperity found in EU member states such as Austria remains elusive and many Hungarians yearn for the social security system of the 1970’s communist era while at the same time subscribing to a resurrection of the strong state. The populist rhetoric of Prime Minister Viktor Orbán draws sharp contrast between the EU’s dream of a Europe without Borders and the localized/nativist vision of Hungarian national identity that resonates with a large part of the polity that provided his FIDESZ (Young Democrats)/ KDNP (Christian Democrats) coalition with parliamentary majorities in 2010 and 2014. Further to the right, Jobbik (the better ones) excoriates both gypsies and Jews for undermining the state. The current refugee crisis has been cast by Orbán as an Islamic tide that will reconfigure Europe into bloodless and docile societies. Orbán’s decision to build a fence in summer 2015 to keep out refugees seems prescient to those subscribing to these nativist beliefs. The State forwards a public presentation of history that absolves the interwar regime of the Lord Protector Miklós Horthy, 1920-1944 of alliance with the Axis and genocide. Though there remains substantial opposition to current nationalist sentiment, the prospects for the survival of liberalism seem bleak without a unified opposition. Interestingly, there remains an embedded dissonance in History curriculum and texts that challenges the State’s interpretation of History. This article studies the state’s public presentation of history in contrast to that found in curriculum and textbooks to understand the contrast between Orbán’s stated aim to create an illiberal state and stories found in texts that undergird the dream of a liberal republic found in the failed revolutions of 1848 and 1956. Disturbingly, previous regimes that extoled the strong state have imaginatively rearranged history so that the two strains of political desire antithetical to each other are reconciled. How does the Hungarian case help us better understand the resurrection of strong state politics that seem to have infiltrated the global stage