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T Michelle Brown,1 Montserrat Vera-Llonch,2 Chisom Kanu,1 Asia Sikora Kessler,2 Aaron Yarlas,2 Sheri E Fehnel1 1Patient-Centered Outcomes Assessment, RTI Health Solutions, Research Triangle Park, NC, USA; 2Health Economics & Outcomes Research, Ionis Pharmaceuticals, Carlsbad, CA, USACorrespondence: Asia Sikora Kessler, Ionis Pharmaceuticals, Carlsbad, CA, USA, Email ASikoraKessler@ionisph.comBackground: Familial chylomicronemia syndrome (FCS) is a rare metabolic disorder that impacts physical, emotional, social, and cognitive functioning. The FCS-Symptom and Impact Scale (FCS-SIS) patient-reported outcome (PRO) measure assesses common symptoms and impacts of FCS. This study was conducted to evaluate cross-sectional psychometric properties of the FCS-SIS and its scoring method.Methods: This multisite, cross-sectional, observational study of individuals with FCS was conducted in the United States and Canada. Participants completed a survey composed of 7 PRO measures, including the FCS-SIS, and questions about clinical characteristics and demographics. The structure of the FCS-SIS was evaluated using inter-item and item-scale correlations and internal consistency reliability. Construct, known-groups, and criterion validity were evaluated by examining associations between FCS-SIS item and composite scores and other measures included within the survey.Results: Most of the 33 participants were female (63.6%) and White (78.1%). On average, participants reported first noticing FCS symptoms at ~16 years, with abdominal pain the most frequently reported initial symptom (n=20). Participants reported 2.5 acute pancreatitis attacks on average over the past year. Average FCS-SIS symptom item scores ranged from 1.8 to 3.9 (on a 0-to-10 scale [none-to-worst-possible]) within the 24-hour recall period, with an average Symptom composite score of 2.7. The average impact item scores on the FCS-SIS ranged from 1.6 to 3.0 (on a 0-to-4 scale), with an average Impact composite score of 2.1. Inter-item correlations between the FCS-SIS Symptom items ranged from 0.32 to 0.78. Corrected item-total correlations were highly satisfactory for Impact items, ranging from 0.62 to 0.85. All a priori validity hypotheses were supported by observed correlations and score differences between known groups.Conclusion: The results of this study support the structure, reliability, and validity of the FCS-SIS, laying the psychometric groundwork for longitudinal evaluation of its utility in assessing treatment benefit in FCS clinical studies.Keywords: psychometric evaluation, FCS, validity, reliability, rare disease, patient reported outcome measure

Daniel Aletaha,1 M Elaine Husni,2 Joseph F Merola,3 Roberto Ranza,4 Heidi Bertheussen,5 Ralph Lippe,6 Pamela M Young,7 Joseph C Cappelleri,8 T Michelle Brown,9 Claire Ervin,9 Ming-Ann Hsu,10 Lara Fallon11 1Division of Rheumatology, Department of Internal Medicine 3, Medical University of Vienna, Vienna, Austria; 2Cleveland Clinic, Department of Rheumatic and Immunologic Diseases, Cleveland, OH, USA; 3Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA; 4Serviço de Reumatología, Universidade Federal de Uberlândia, Uberlândia, Minas Gerais, Brazil; 5Patient Representative, Oslo, Norway; 6Inflammation & Immunology, Pfizer Pharma GmbH, Berlin, Germany; 7Inflammation & Immunology, Pfizer Inc, Collegeville, PA, USA; 8Statistics, Pfizer Inc, Groton, CT, USA; 9RTI Health Solutions, Research Triangle Park, NC, USA; 10Health Economics & Outcomes Research, Pfizer Inc, Groton, CT, USA; 11Medical Affairs, Pfizer Inc, Montreal, QC, CanadaCorrespondence: Daniel AletahaDivision of Rheumatology, Department of Internal Medicine 3, Medical University of Vienna, Währinger Gürtel 18– 20, Vienna 1090, AustriaEmail daniel.aletaha@meduniwien.ac.atObjective: Qualitative research exploring patient preferences regarding the mode of treatment administration for psoriatic arthritis (PsA) is limited. We report patient preferences and their reasons across PsA treatment modes.Methods: In this global, cross-sectional, qualitative study, interviews were conducted with adult patients with PsA in Brazil, France, Germany, Italy, Spain, the UK, and the US. Patients were currently taking a disease-modifying antirheumatic drug (DMARD). Patients indicated the order and strength of preference (0– 100; 100 = strongest) across four modes of treatment administration: oral (once daily), self-injection (weekly), clinic injection (weekly), and infusion (monthly); reasons for preferences were qualitatively assessed. Descriptive statistics were reported. Fisher’s exact tests and t-tests were conducted for treatment mode outcomes.Results: Overall, 85 patients were interviewed (female, 60.0%; mean age, 49.8 years). First-choice ranking (%) and mean [standard deviation] preference points were: oral (49.4%; 43.9 [31.9]); self-injection (34.1%; 32.4 [24.8]); infusion (15.3%; 14.5 [20.0]); clinic injection (1.2%; 9.2 [10.0]). Of 48 (56.5%) patients with a strong first-choice preference (ie point allocation ≥ 60), 66.7% chose oral administration. Self-injection was most often selected as second choice (51.8%), clinic injection as third (49.4%), and infusion as fourth (47.1%). Oral administration was the first-choice preference in the US (88.0% vs 38.0% in Europe). The most commonly reported reason for oral administration as the first choice was speed and ease of administration (76.2%); for self-injection, this was convenience (75.9%). The most commonly reported reason for avoiding oral administration was concern about possible drug interactions (63.6%); for self-injection, this was a dislike of needles or the injection process (66.7%).Conclusion: Patients with PsA preferred oral treatment administration, followed by self-injection; convenience factors were common reasons for these preferences. Overall, 43.5% of patients did not feel strongly about their first-choice preference and may benefit from discussions with healthcare professionals about PsA treatment administration options.Keywords: psoriatic arthritis, patient preference, qualitative research, treatment administration

Peter C Taylor, 1 Neil Betteridge, 2 T Michelle Brown, 3 John Woolcott, 4 Alan J Kivitz, 5 Cristiano Zerbini, 6 Diane Whalley, 7 Oyebimpe Olayinka-Amao, 3 Connie Chen, 8 Palle Dahl, 9 Dario Ponce de Leon, 10 David Gruben, 11 Lara Fallon 12 1Botnar Research Centre, University of Oxford, Oxford, UK; 2Neil Betteridge Associates, London, UK; 3Patient-Centered Outcomes Assessment Group, RTI Health Solutions, Research Triangle Park, NC, USA; 4Patient and Health Impact, Health Economics and Outcomes Research, Pfizer Inc, Collegeville, PA, USA; 5Altoona Center for Clinical Research, Duncansville, PA, USA; 6Department of Rheumatology, Centro Paulista De Investigação Clinica, São Paulo, Brazil; 7Patient-Centered Outcomes Assessment Group, RTI Health Solutions, Manchester, UK; 8Xeljanz, Rheumatology, Inflammation & Immunology Medical Affairs, Pfizer Inc, New York, NY, USA; 9Medical Affairs, International Developed Markets, Inflammation & Immunology, Pfizer Inc, Ballerup, Denmark; 10Medical Affairs Latin-America, Pfizer Inc, New York, NY, USA; 11Statistical Research and Data Science Center, Pfizer Inc, Groton, CT, USA; 12Global Medical Affairs, Pfizer Inc, Montreal, QC, CanadaCorrespondence: Peter C TaylorBotnar Research Centre, University of Oxford, Windmill Road, Headington, Oxford OX3 7LD, UKTel +441865 227323Email peter.taylor@kennedy.ox.ac.ukPurpose: Current knowledge of the reasons for patients’ preference for rheumatoid arthritis (RA) treatment modes is limited. This study was designed to identify preferences for four treatment modes, and to obtain in-depth information on the reasons for these preferences.Patients and Methods: In this multi-national, cross-sectional, qualitative study, in-depth interviews were conducted with adult patients with RA in the United States, France, Germany, Italy, Spain, Switzerland, the United Kingdom, and Brazil. Patients’ strength of preference was evaluated using a 100-point allocation task (0– 100; 100=strongest) across four treatment modes: oral, self-injection, clinic-injection, and infusion. Qualitative descriptive analysis methods were used to identify, characterize, and summarize patterns found in the interview data relating to reasons for these preferences.Results: 100 patients were interviewed (female, 75.0%; mean age, 53.9 years; mean 11.6 years since diagnosis). Among the four treatment modes, oral administration was allocated the highest mean (standard deviation) preference points (47.3 [33.1]) and was ranked first choice by the greatest percentage of patients (57.0%), followed by self-injection (29.7 [27.7]; 29.0%), infusion (15.4 [24.6]; 16.0%), and clinic-injection (7.5 [14.1]; 2.0%). Overall, 56.0% of patients had a “strong” first-choice preference (ie, point allocation ≥ 70); most of these patients chose oral (62.5%) vs self-injection (23.2%), infusion (10.7%), or clinic-injection (3.6%). Speed and/or ease of administration were the most commonly reported reasons for patients choosing oral (52.6%) or self-injection (55.2%). The most common reasons for patients not choosing oral or self-injection were not wanting to take another pill (37.2%) and avoiding pain due to needles (46.5%), respectively.Conclusion: These data report factors important to patients regarding preferences for RA treatment modes. Patients may benefit from discussions with their healthcare professionals and/or patient support groups, regarding RA treatment modes, to facilitate shared decision-making.Keywords: drug administration, patient perspective, qualitative research, surveys

Emily B Levitan,1 Christopher Gamboa,1 Monika M Safford,2 Dana V Rizk,3 Todd M Brown,4 Elsayed Z Soliman,5 Paul Muntner11Department of Epidemiology, 2Division of Preventive Medicine, 3Division of Nephrology, 4Division of Cardiology, University of Alabama at Birmingham, Birmingham, AL, USA; 5Epidemiological Cardiology Research Center, Wake Forest University School of Medicine, Winston Salem, NC, USABackground: Individuals with unrecognized myocardial infarction (UMI) have similar risks for cardiovascular events and mortality as those with recognized myocardial infarction (RMI). The prevalence of cardioprotective medication use and blood pressure and low-density lipoprotein cholesterol control among individuals with UMI is unknown.Methods: Participants from the REasons for Geographic And Racial Differences in Stroke (REGARDS) study who were recruited between May 2004 and October 2007 received baseline twelve-lead electrocardiograms (n = 21,036). Myocardial infarction (MI) status was characterized as no MI, UMI (electrocardiogram abnormalities consistent with MI without self-reported history; n = 949; 4.5%), and RMI (self-reported history of MI; n = 1574; 7.5%).Results: For participants with no MI, UMI, and RMI, prevalence of use was 38.4%, 44.4%, and 75.7% for aspirin; 18.0%, 25.8%, and 57.2% for beta blockers; 31.7%, 38.7%, and 55.0% for angiotensin converting enzyme inhibitors or angiotensin receptor blockers; and 28.1%, 33.9%, and 64.1% for statins, respectively. Participants with RMI were 35% more likely to have low-density lipoprotein cholesterol < 100 mg/dL than participants with UMI (prevalence ratio = 1.35, 95% confidence interval 1.19–1.52). Blood pressure control (

We present the color-magnitude diagrams and star formation histories (SFHs) of seven ultra-faint dwarf galaxies: Horologium 1, Hydra 2, Phoenix 2, Reticulum 2, Sagittarius 2, Triangulum 2, and Tucana 2, derived from high-precision Hubble Space Telescope photometry. We find that the SFH of each galaxy is consistent with them having created at least 80% of the stellar mass by z ~ 6. For all galaxies, we find quenching times older than 11.5 Gyr ago, compatible with the scenario in which reionization suppresses the star formation of small dark matter halos. However, our analysis also reveals some differences in the SFHs of candidate Magellanic Cloud satellites, i.e., galaxies that are likely satellites of the Large Magellanic Cloud and that entered the Milky Way potential only recently. Indeed, Magellanic satellites show quenching times about 600 Myr more recent with respect to those of other Milky Way satellites, on average, even though the respective timings are still compatible within the errors. This finding is consistent with theoretical models that suggest that satellites' SFHs may depend on their host environment at early times, although we caution that within the error bars all galaxies in our sample are consistent with being quenched at a single epoch.

NASA's Kepler mission has provided several thousand transiting planet candidates during the 4 yr of its nominal mission, yet only a small subset of these candidates have been confirmed as true planets. Therefore, the most fundamental question about these candidates is the fraction of bona fide planets. Estimating the rate of false positives of the overall Kepler sample is necessary to derive the planet occurrence rate. We present the results from two large observational campaigns that were conducted with the Spitzer Space Telescope during the the Kepler mission. These observations are dedicated to estimating the false positive rate (FPR) among the Kepler candidates. We select a sub-sample of 51 candidates, spanning wide ranges in stellar, orbital, and planetary parameter space, and we observe their transits with Spitzer at 4.5 μm. We use these observations to measures the candidate's transit depths and infrared magnitudes. An authentic planet produces an achromatic transit depth (neglecting the modest effect of limb darkening). Conversely a bandpass-dependent depth alerts us to the potential presence of a blending star that could be the source of the observed eclipse: a false positive scenario. For most of the candidates (85%), the transit depths measured with Kepler are consistent with the transit depths measured with Spitzer as expected for planetary objects, while we find that the most discrepant measurements are due to the presence of unresolved stars that dilute the photometry. The Spitzer constraints on their own yield FPRs between 5% and depending on the Kepler Objects of Interest. By considering the population of the Kepler field stars, and by combining follow-up observations (imaging) when available, we find that the overall FPR of our sample is low. The measured upper limit on the FPR of our sample is 8.8% at a confidence level of 3σ. This observational result, which uses the achromatic property of planetary transit signals that is not investigated by the Kepler observations, provides an independent indication that Kepler's FPR is low.

© 2015. The American Astronomical Society. All rights reserved. The Legacy ExtraGalactic UV Survey (LEGUS) is a Cycle 21 Treasury program on the Hubble Space Telescope aimed at the investigation of star formation and its relation with galactic environment in nearby galaxies, from the scales of individual stars to those of ∼kiloparsec-size clustered structures. Five-band imaging from the nearultraviolet to the I band with the Wide-Field Camera 3 (WFC3), plus parallel optical imaging with the Advanced Camera for Surveys (ACS), is being collected for selected pointings of 50 galaxies within the local 12 Mpc. The filters used for the observations with the WFC3 are F275W (λ2704 A˚), F336W(λ3355 A˚), F438W(λ4325 A˚), F555W(λ5308 A˚), and F814W(ë8024 A˚); the parallel observations with the ACS use the filters F435W (λ4328 A˚), F606W(λ5921 A˚), and F814W(λ8057 A˚). The multiband images are yielding accurate recent (≲50 Myr) star formation histories from resolved massive stars and the extinction-corrected ages and masses of star clusters and associations. The extensive inventories of massive stars and clustered systems will be used to investigate the spatial and temporal evolution of star formation within galaxies. This will, in turn, inform theories of galaxy evolution and improve the understanding of the physical underpinning of the gas-star formation relation and the nature of star formation at high redshift. This paper describes the survey, its goals and observational strategy, and the initial scientific results. Because LEGUS will provide a reference survey and a foundation for future observations with the James Webb Space Telescope and with ALMA, a large number of data products are planned for delivery to the community.

This study compares the production of hydrogen with high temperature fuel cells (HTFCs) that tri-generate power, heat and hydrogen to distributed and centralized steam methane reformation (SMR) supply chains. The defined supply chain steps of hydrogen production include: production, treatment, distribution, storage, dispensing and use. Different technologies for each step in the supply chain have been analyzed from an energy standpoint, resulting in ten different supply chain scenarios. Results show that liquefaction of hydrogen is the most energy intensive of all the treatment processes and that it is only effective for long delivery distances. When the energy required for the hydrogen treatment (i.e., liquefaction, compression) is included, it is shown that compressed gas hydrogen at 200 bar is the least energy intensive for delivery distances shorter than 84 km if transported by diesel truck. For distances longer than 84 km, 500 bar compressed hydrogen is more efficiently transported than at 200 bar compressed hydrogen. For distances larger than 550 km, liquefied hydrogen is more efficiently distributed than compressed hydrogen at 500 bar. Results show that the highest supply chain efficiency corresponds to distributed hydrogen production via tri-generating HTFC (∼76%) followed by centralized SMR with 500 bar compressed hydrogen distribution (∼71%). The lowest supply chain efficiency values correspond to distributed SMR plants (∼60%) and centralized SMR with transportation of hydrogen in liquid form (

A transition from gasoline internal combustion engine vehicles to hydrogen fuel cell electric vehicles (FCEVs) is likely to emerge as a major component of the strategy to meet future greenhouse gas reduction, air quality, fuel independence, and energy security goals. Advanced infrastructure planning can minimize the cost of hydrogen infrastructure while assuring that energy and environment benefits are achieved. This study presents a comprehensive advanced planning methodology for the deployment of hydrogen infrastructure, and applies the methodology to delineate fully built-out infrastructure strategies, assess the associated energy and environment impacts, facilitate the identification of an optimal infrastructure roll-out strategy, and identify the potential for renewable hydrogen feedstocks. The South Coast Air Basin of California, targeted by automobile manufacturers for the first regional commercial deployment of FCEVs, is the focus for the study. The following insights result from the application of the methodology:Compared to current gasoline stations, only 11%-14% of the number of hydrogen fueling stations can provide comparable accessibility to drivers in a targeted region.To meet reasonable capacity demand for hydrogen fueling, approximately 30% the number of hydrogen stations are required compared to current gasoline stations.Replacing gasoline vehicles with hydrogen FCEVs has the potential to (1) reduce the emission of greenhouse gases by more than 80%, reduce energy requirements by 42%, and virtually eliminate petroleum consumption from the passenger vehicle sector, and (2) significantly reduce urban concentrations of ozone and PM2.5.Existing sources of biomethane in the California South Coast Air Basin can provide up to 30% of the hydrogen fueling demand for a fully built-out hydrogen FCEV scenario.A step-wise transition of judiciously located existing gasoline stations to dispense and accommodate the increasing demand for hydrogen addresses proactively key infrastructure deployment challenges including a viable business model, zoning, permitting, and public acceptance. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

The constantly evolving western grid of the United States is characterized by complex generation dispatch based on economics, contractual agreements, and regulations. The future electrification of transportation via plug-in electric vehicles calls for an energy and emissions analysis of electric vehicle (EV) penetration scenarios based on realistic resource dispatch. A resource dispatch and emissions model for the western grid is developed and a baseline case is modeled. Results are compared with recorded data to validate the model and provide confidence in the analysis of EV-grid interaction outlooks. A modeled dispatch approach, based on a correlation between actual historical dispatch and system load data, is exercised to show the impacts (emission intensity, temporally resolved load demand) associated with EV penetration on the western grid. The plug-in hybrid electric vehicle (PHEV) and selected charging scenarios are the focus for the analysis. The results reveal that (1) a correlation between system load and resource group capacity factor can be utilized in dispatch modeling, (2) the hourly emissions intensity of the grid depends upon PHEV fleet charge scenario, (3) emissions can be reduced for some species depending on the PHEV fleet charge scenario, and (4) the hourly model resolution of changes in grid emissions intensity can be used to decide on preferred fleet-wide charge profiles. © 2010 Elsevier B.V. All rights reserved.

The introduction of hydrogen infrastructure and fuel cell vehicles (FCVs) to gradually replace gasoline internal combustion engine vehicles can provide environment and energy security benefits. The deployment of hydrogen fueling infrastructure to support the demonstration and commercialization of FCVs remains a critical barrier to transitioning to hydrogen as a transportation fuel. This study utilizes an engineering methodology referred to as the Spatially and Temporally Resolved Energy and Environment Tool (STREET) to demonstrate how systematic planning can optimize early investments in hydrogen infrastructure in a way that supports and encourages growth in the deployment of FCVs while ensuring that the associated environment and energy security benefits are fully realized. Specifically, a case study is performed for the City of Irvine, California - a target area for FCV deployment - to determine the optimized number and location of hydrogen fueling stations required to provide a bridge to FCV commercialization, the preferred rollout strategy for those stations, and the environmental impact associated with three near-term scenarios for hydrogen production and distribution associated with local and regional sources of hydrogen available to the City. Furthermore, because the State of California has adopted legislation imposing environmental standards for hydrogen production, results of the environmental impact assessment for hydrogen production and distribution scenarios are measured against the California standards. The results show that significantly fewer hydrogen fueling stations are required to provide comparable service to the existing gasoline infrastructure, and that key community statistics are needed to inform the preferred rollout strategy for the stations. Well-to-wheel (WTW) greenhouse gas (GHG) emissions, urban criteria pollutants, energy use, and water use associated with hydrogen and FCVs can be significantly reduced in comparison to the average parc of gasoline vehicles regardless of whether hydrogen is produced and distributed with an emphasis on conventional resources (e.g., natural gas), or on local, renewable resources. An emphasis on local renewable resources to produce hydrogen further reduces emissions, energy use, and water use associated with hydrogen and FCVs compared to an emphasis on conventional resources. All three hydrogen production and distribution scenarios considered in the study meet California's standards for well-to-wheel GHG emissions, and well-to-tank emissions of urban ROG and NOX. Two of the three scenarios also meet California's standard that 33% of hydrogen must be produced from renewable feedstocks. Overall, systematic planning optimizes both the economic and environmental impact associated with the deployment of hydrogen infrastructure and FCVs. © 2010 Professor T. Nejat Veziroglu.

The Lick AGN Monitoring Project targeted 13 nearby Seyfert 1 galaxies with the intent of measuring the masses of their central black holes using reverberation mapping. The sample includes 12 galaxies selected to have black holes with masses roughly in the range 106-107 M ⊙, as well as the well-studied active galactic nucleus (AGN) NGC 5548. In conjunction with a spectroscopic monitoring campaign, we obtained broadband B and V images on most nights from 2008 February through 2008 May. The imaging observations were carried out by four telescopes: the 0.76 m Katzman Automatic Imaging Telescope, the 2 m Multicolor Active Galactic Nuclei Monitoring telescope, the Palomar 60 inch (1.5 m) telescope, and the 0.80 m Tenagra II telescope. Having well-sampled light curves over the course of a few months is useful for obtaining the broad-line reverberation lag and black hole mass, and also allows us to examine the characteristics of the continuum variability. In this paper, we discuss the observational methods and the photometric measurements, and present the AGN continuum light curves. We measure various variability characteristics of each of the light curves. We do not detect any evidence for a time lag between the B- and V-band variations, and we do not find significant color variations for the AGNs in our sample. © 2009. The American Astronomical Society. All rights reserved.

This paper describes the development of a unique single cell proton exchange membrane (PEM) test fixture to independently investigate the effects of gas sealing and assembly pressure. The test fixture is shown to provide useful insights into the effects of pressure on contact resistance. Two versions of gas diffusion layers (GDL) were tested to demonstrate that contact pressure significantly affects cell performance. In general, performance tends to increase with clamping force until a plateau is reached, after which performance drops rapidly. The rapid drop at high GDL pressure is due to puncture of the membrane or GDL mechanical failure. The performance improvements with pressure may be due to reductions in electrical or ionic resistance. © The Electrochemical Society.

As proton exchange membrane fuel cell technology advances, the need for hydrogen storage intensifies. Metal hydride alloys offer one potential solution. However, for metal hydride tanks to become a viable hydrogen storage option, the dynamic performance of practical tank geometries and configurations must be understood and incorporated into fuel cell system analyses. A dynamic, axially-symmetric, multi-nodal metal hydride tank model has been created in Matlab-Simulink® as an initial means of providing insight and analysis capabilities for the dynamic performance of commercially available metal hydride systems. Following the original work of Mayer et al. [Mayer U, Groll M, Supper W. Heat and mass transfer in metal hydride reaction beds: experimental and theoretical results. Journal of the Less-Common Metals 1987;131:235-44], this model employs first principles heat transfer and fluid flow mechanisms together with empirically derived reaction kinetics. Energy and mass balances are solved in cylindrical polar coordinates for a cylindrically shaped tank. The model tank temperature, heat release, and storage volume have been correlated to an actual metal hydride tank for static and transient absorption and desorption processes. A sensitivity analysis of the model was accomplished to identify governing physics and to identify techniques to lessen the computational burden for ease of use in a larger system model. The sensitivity analysis reveals the basis and justification for model simplifications that are selected. Results show that the detailed and simplified models both well predict observed stand-alone metal hydride tank dynamics, and an example of a reversible fuel cell system model incorporating each tank demonstrates the need for model simplification. © 2008 International Association for Hydrogen Energy.

A dynamic model of a discrete reversible fuel cell (RFC) system has been developed in a Matlab Simulink® environment. The model incorporates first principles dynamic component models of a proton exchange membrane (PEM) fuel cell, a PEM electrolyzer, a metal hydride hydrogen storage tank, and a cooling system radiator, as well as empirical models of balance of plant components. Dynamic simulations show unique charging and discharging control issues and highlight factors contributing to overall system efficiency. © 2008 Elsevier B.V. All rights reserved.

As proton exchange membrane fuel cell technology advances, the need for hydrogen storage intensifies. Metal hydride alloys offer one potential solution. However, for metal hydride tanks to become a viable hydrogen storage option, the dynamic performance of different tank geometries and configurations must be evaluated. In an effort to relate tank performance to geometry and operating conditions, a dynamic, two-dimensional, multi-nodal metal hydride tank model has been created in Matlab-Simulink®. Following the original work of Mayer, Groll, and Supper1 and the more recent paper from Aldas, Mat, and Kaplan2, this model employs first principle heat transfer and fluid flow mechanisms together with empirically derived reaction kinetics. Energy and mass balances are solved in cylindrical polar coordinates for a cylindrically shaped tank. The model tank temperature, heat release, and storage volume have been correlated to an actual metal hydride tank for static and transient adsorption and desorption processes. The dynamic model is found to accurately predict observed hardware performance characteristics portending a capability to well simulate the dynamic performance of more complex tank geometries and configurations. As an example, a cylindrical tank filled via an internal concentric axial tube is considered. Copyright © 2006 by ASME.

We report results from a large Hubble Space Telescope project to observe asignificant (~34,000) ensemble of main sequence stars in the globular cluster47 Tucanae with a goal of defining the frequency of inner-orbit, gas-giantplanets. Simulations based on the characteristics of the 8.3 days oftime-series data in the F555W and F814W WFPC2 filters show that ~17 planetsshould be detected by photometric transit signals if the frequency of hotJupiters found in the solar neighborhood is assumed to hold for 47 Tuc. Theexperiment provided high-quality data sufficient to detect planets. A fullanalysis of these WFPC2 data reveals ~75 variables, but NO light curvesresulted for which a convincing interpretation as a planet could be made. Theplanet frequency in 47 Tuc is at least an order of magnitude below that for thesolar neighborhood. The cause of the absence of close-in planets in 47 Tuc isnot yet known; presumably the low metallicity and/or crowding of 47 Tucinterfered with planet formation, with orbital evolution to close-in positions,or with planet survival.